WorldWideScience

Sample records for plasmid-mediated quinolone resistance

  1. Plasmid mediated quinolone resistance in Enterobacteriaceae

    NARCIS (Netherlands)

    Veldman, K.T.; LS Klinisch Onderzoek Wagenaar

    2014-01-01

    This thesis describes the occurrence of Plasmid Mediated Quinolone Resistance (PMQR) in Salmonella and E. coli from The Netherlands and other European countries. Furthermore, the genetic background of these genes was characterized. Fluoroquinolones are widely used antibiotics in both human and

  2. Plasmid mediated quinolone resistance in Enterobacteriaceae

    NARCIS (Netherlands)

    Veldman, K.T.; LS Klinisch Onderzoek Wagenaar

    2014-01-01

    This thesis describes the occurrence of Plasmid Mediated Quinolone Resistance (PMQR) in Salmonella and E. coli from The Netherlands and other European countries. Furthermore, the genetic background of these genes was characterized. Fluoroquinolones are widely used antibiotics in both human and veter

  3. Plasmid mediated quinolone resistance in Enterobacteriaceae

    NARCIS (Netherlands)

    Veldman, K.T.; LS Klinisch Onderzoek Wagenaar

    2014-01-01

    This thesis describes the occurrence of Plasmid Mediated Quinolone Resistance (PMQR) in Salmonella and E. coli from The Netherlands and other European countries. Furthermore, the genetic background of these genes was characterized. Fluoroquinolones are widely used antibiotics in both human and veter

  4. [Investigation of plasmid-mediated quinolone resistance in Escherichia coli strains].

    Science.gov (United States)

    Aktepe, Orhan Cem; Aşık, Gülşah; Cetinkol, Yeliz; Biçmen, Meral; Gülay, Zeynep

    2012-01-01

    Quinolones are widely used antimicrobial agents, particularly for the treatment of infections caused by gram-negative bacilli such as E.coli. As a consequence, quinolone resistance has been increasing among this species in recent years. Bacterial resistance to quinolones usually results from mutations in the chromosomal genes which encode topoisomerases and also the expression of efflux pumps and loss of porines contributed to development of quinolone resistance. However, recent studies have shown that the spread and increase of quinolone resistance may be due to the transfer of plasmid-mediated genes. To date, three groups of plasmid-mediated quinolone resistance genes, namely qnr, aac(6')-Ib-cr, and qepA, have been described. The aim of this study was to investigate the presence of plasmid-mediated quinolone resistance genes in E.coli clinical isolates. A total of 112 quinolone-resistant E.coli strains isolated from different clinical specimens (84 urine, 16 blood, 10 wound, 2 bronchoalveolar lavage) of which 78 (69.6%) were extended-spectrum beta-lactamase (ESBL) positive, in Afyon Kocatepe University Hospital, Microbiology Laboratory were included in the study. In the isolates, qnrA, qnrB, qnrS, qnrC, qepA, and aac(6')-1b-cr plasmid genes were analysed by polymerase chain reaction (PCR). After aac(6')- 1b determinant was amplified by PCR, all aac(6')-1b positive amplicons were analyzed by digestion with BseGI restriction enzyme to identify aac(6')-1b-cr variant. It was found that, none of the strains horboured qnrA, qnrB, qnrS, qnrC and qepA genes, however, plasmid-mediated quinolone resistance gene aac(6')-1b-cr was found positive in 59.8% (67/112) of the strains. It was notable that 86.6% (58/67) of those isolates were ESBL producers. The rates of quinolone resistance among E.coli isolates infections were high in our region and an increasing trend has been observed in recent years. Our data indicated that the presence of plasmid- mediated resistance genes

  5. Prevalence of plasmid-mediated quinolone resistance determinants among oxyiminocephalosporin-resistant Enterobacteriaceae in Argentina

    Directory of Open Access Journals (Sweden)

    Giovanna Rincon Cruz

    2013-11-01

    Full Text Available High quinolone resistance rates were observed among oxyiminocephalosporin-resistant enterobacteria. In the present study, we searched for the prevalence of plasmid-mediated quinolone resistance (PMQR genes within the 55 oxyiminocephalosporin-resistant enterobacteria collected in a previous survey. The main PMQR determinants were aac(6'-Ib-cr and qnrB, which had prevalence rates of 42.4% and 33.3%, respectively. The aac(6'-Ib-cr gene was more frequently found in CTX-M-15-producing isolates, while qnrB was homogeneously distributed among all CTX-M producers.

  6. Plasmid-mediated quinolone resistance among non-typhi Salmonella enterica isolates, USA

    Science.gov (United States)

    We determined the prevalence of plasmid-mediated quinolone resistance mechanisms among non-Typhi Salmonella (NTS) spp. isolates from humans, food animals, and retail meat in the United States in 2007. Fifty-one (2.4%) of human isolates (n=2165), 5 (1.6%) of isolates from animal isolates (n=1915) an...

  7. Prevalence of plasmid-mediated quinolone resistance determinants in Enterobacteriaceae strains isolated in North-East Italy.

    Science.gov (United States)

    Kocsis, B; Mazzariol, A; Kocsis, E; Koncan, R; Fontana, R; Cornaglia, G

    2013-02-01

    We investigated the prevalence of plasmid-mediated quinolone resistance genes in 756 clinical isolates of Enterobacteriaceae originating from Microbiology Diagnostic Laboratories of North-East Italy. Five point zero two percent of isolates carried a qnr determinant while the aac(6')-Ib-cr determinant was detected in 9·25% of isolates. We also investigated the association between the plasmid-mediated quinolone resistance and the beta-lactamase genes, and characterized the plasmids carrying these determinants of resistance.

  8. Plasmid-mediated quinolone resistance in Enterobacteriaceae: a systematic review with a focus on Mediterranean countries.

    Science.gov (United States)

    Yanat, B; Rodríguez-Martínez, J-M; Touati, A

    2017-03-01

    Quinolones are a family of synthetic broad-spectrum antimicrobial drugs. These molecules have been widely prescribed to treat various infectious diseases and have been classified into several generations based on their spectrum of activity. Quinolones inhibit bacterial DNA synthesis by interfering with the action of DNA gyrase and topoisomerase IV. Mutations in the genes encoding these targets are the most common mechanisms of high-level fluoroquinolone resistance. Moreover, three mechanisms for plasmid-mediated quinolone resistance (PMQR) have been discovered since 1998 and include Qnr proteins, the aminoglycoside acetyltransferase AAC(6')-Ib-cr, and plasmid-mediated efflux pumps QepA and OqxAB. Plasmids with these mechanisms often encode additional antimicrobial resistance (extended spectrum beta-lactamases [ESBLs] and plasmidic AmpC [pAmpC] ß-lactamases) and can transfer multidrug resistance. The PMQR determinants are disseminated in Mediterranean countries with prevalence relatively high depending on the sources and the regions, highlighting the necessity of long-term surveillance for the future monitoring of trends in the occurrence of PMQR genes.

  9. Plasmid-mediated quinolone resistance; interactions between human, animal and environmental ecologies

    Directory of Open Access Journals (Sweden)

    Laurent ePOIREL

    2012-02-01

    Full Text Available Resistance to quinolones and fluoroquinolones is being increasingly reported among human but also veterinary isolates during the last two to three decades, very likely as a consequence of the large clinical usage of those antibiotics. Even if the principle mechanisms of resistance to quinolones are chromosome-encoded, due to modifications of molecular targets (DNA gyrase and topoisomerase IV, decreased outer-membrane permeability (porin defect and overexpression of naturally-occurring efflux, the emergence of plasmid-mediated quinolone resistance (PMQR has been reported since 1998. Although these PMQR determinants confer low-level resistance to quinolones and/or fluoroquinolones, they are a favorable background for selection of additional chromosome-encoded quinolone resistance mechanisms. Different transferable mechanisms have been identified, corresponding to the production of Qnr proteins, of the aminoglycoside acetyltransferase AAC(6’-Ib-cr, or of the QepA-type or OqxAB-type efflux pumps. Qnr proteins protect target enzymes (DNA gyrase and type IV topoisomerase from quinolone inhibition (mostly nalidixic acid. The AAC(6’-Ib-cr determinant acetylates several fluoroquinolones, such as norfloxacin and ciprofloxacin. Finally, the QepA and OqxAB efflux pumps extrude fluoroquinolones from the bacterial cell. A series of studies have identified the environment to be a reservoir of PMQR genes, with farm animals and aquatic habitats being significantly involved. In addition, the origin of the qnr genes has been identified, corresponding to the waterborne species Shewanella sp. Altogether, the recent observations suggest that the aquatic environment might constitute the original source of PMQR genes, that would secondly spread among animal or human isolates.

  10. Bacterial plasmid-mediated quinolone resistance genes in aquatic environments in China

    Science.gov (United States)

    Yan, Lei; Liu, Dan; Wang, Xin-Hua; Wang, Yunkun; Zhang, Bo; Wang, Mingyu; Xu, Hai

    2017-01-01

    Emerging antimicrobial resistance is a major threat to human’s health in the 21st century. Understanding and combating this issue requires a full and unbiased assessment of the current status on the prevalence of antimicrobial resistance genes and their correlation with each other and bacterial groups. In aquatic environments that are known reservoirs for antimicrobial resistance genes, we were able to reach this goal on plasmid-mediated quinolone resistance (PMQR) genes that lead to resistance to quinolones and possibly also to the co-emergence of resistance to β-lactams. Novel findings were made that qepA and aac-(6′)-Ib genes that were previously regarded as similarly abundant with qnr genes are now dominant among PMQR genes in aquatic environments. Further statistical analysis suggested that the correlation between PMQR and β-lactam resistance genes in the environment is still weak, that the correlations between antimicrobial resistance genes could be weakened by sufficient wastewater treatment, and that the prevalence of PMQR has been implicated in environmental, pathogenic, predatory, anaerobic, and more importantly, human symbiotic bacteria. This work provides a comprehensive analysis of PMQR genes in aquatic environments in Jinan, China, and provides information with which combat with the antimicrobial resistance problem may be fought. PMID:28094345

  11. Plasmid-mediated quinolone resistance among extended spectrum beta lactase producing Enterobacteriaceae from bloodstream infections.

    Science.gov (United States)

    Domokos, Judit; Kristóf, Katalin; Szabó, Dóra

    2016-09-01

    The purpose of this study was to determine prevalence and molecular characterization of plasmid-mediated quinolone resistance (PMQR) genes [qnrA, qnrB, qnrC, qnrD, qnrS, aac(6')-Ib-cr, qepA, and oqxAB] among extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella spp. isolates from bloodcultures in Hungary. A total of 103 isolates were tested for quinolone susceptibility by microdilution method and PMQR genes were detected by polymerase chain reaction. About 40 ESBL-producing E. coli (39%) and 50 ESBL-producing Klebsiella spp. strains (48%) were resistant to ciprofloxacin; 40 ESBL-producing E. coli (39%) and 47 ESBL-producing Klebsiella spp. strains (45%) were resistant to levofloxacin; and 88 strains including 40 ESBL-producing E. coli (39%) and 48 (47%) ESBL-producing Klebsiella spp. were resistant to moxifloxacin. Among the 103 ESBL-producing isolates, 77 (75%) isolates (30 E. coli and 47 Klebsiella spp.) harbored PMQR genes. The most commonly detected gene was aac(6')-Ib-cr (65%). The occurrence of qnrS gene was 6%. Interestingly, qnrA, qnrB, qnrC, qnrD, and qepA were not found in any isolates. Among 77 PMQR-positive isolates, 27 (35.1%) and 1 (1.3%) carried two and three different PMQR genes, respectively. Only Klebsiella spp. harbored more than one PMQR genes. Observing prevalence of PMQR genes in the last 8 years, the increasing incidence of aac(6')-Ib-cr and oqxAB can be seen. Our results highlight high frequency of PMQR genes among ESBL-producing Klebsiella pneumoniae and E. coli isolates with an increasing dynamics in Hungary.

  12. Plasmid-mediated quinolone resistance in typhoidal Salmonellae: A preliminary report from South India

    Directory of Open Access Journals (Sweden)

    V K Geetha

    2014-01-01

    Full Text Available Background: Fluoroquinolones are the drugs extensively employed for the treatment of Salmonella infections. Over the couple of decades that have elapsed since the introduction of fluoroquinolones, resistance to these agents by Enterobacteriaceae family members has become common and widespread. Although fluoroquinolone resistance is mediated by genomic DNA (deoxyribonucleic acid as well as plasmid DNA, the plasmid-mediated quinolone resistance (PMQR facilitates higher level resistance by interacting with genomic mechanism and is capable of horizontal spread. Materials and Methods: During a period of 1-year, 63 typhoidal Salmonellae were isolated from 14,050 blood cultures and one parietal wall abscess. 36 (56.25% were Salmonella Typhi and 27 (42% were Salmonella Paratyphi A. They were all screened for resistance by the disc diffusion method and their minimum inhibitory concentrations were determined using agar dilution, broth dilution and E-strip method. Ciprofloxacin resistant isolates were screened for PMQR determinants by polymerase chain reaction assay. Results: All the 63 isolates were resistant to nalidixic acid. Among the 36 S. Typhi isolates 20 were resistant to ciprofloxacin, of which 14 carried the plasmid gene qnrB and one carried the aac(6′-Ib-cr gene. qnrA and qnrS genes were not detected. Ciprofloxacin resistance was not seen in any of the S. Paratyphi A isolates. Conclusion: The antibiotic sensitivity pattern of typhoidal Salmonellae shows an increasing trend of PMQR. The allele B of qnr gene was found to be the predominant cause of PMQR in this study.

  13. Responses of plasmid-mediated quinolone resistance genes and bacterial taxa to (fluoro)quinolones-containing manure in arable soil.

    Science.gov (United States)

    Xiong, Wenguang; Sun, Yongxue; Ding, Xueyao; Zhang, Yiming; Zhong, Xiaoxia; Liang, Wenfei; Zeng, Zhenling

    2015-01-01

    The aim of the present study was to investigate the fate of plasmid-mediated quinolone resistance (PMQR) genes and the disturbance of soil bacterial communities posed by (fluoro)quinolones (FQNs)-containing manure in arable soil. Representative FQNs (enrofloxacin (ENR), ciprofloxacin (CIP) and norfloxacin (NOR)), PMQR genes (qepA, oqxA, oqxB, aac(6')-Ib-cr and qnrS) and bacterial communities in untreated soil, +manure and +manure+FQNs groups were analyzed using culture independent methods. The significantly higher abundance of oqxA, oqxB and aac(6')-Ib-cr, and significantly higher abundance of qnrS in +manure group than those in untreated soil disappeared at day 30 and day 60, respectively. All PMQR genes (oqxA, oqxB, aac(6')-Ib-cr and qnrS) dissipated 1.5-1.7 times faster in +manure group than those in +manure+FQNs group. The disturbance of soil bacterial communities posed by FQNs-containing manure was also found. The results indicated that significant effects of PMQR genes (oqxA, oqxB, aac(6')-Ib and qnrS) on arable soils introduced by manure disappeared 2 month after manure application. FQNs introduced by manure slowed down the dissipation of PMQR genes. The presence of high FQNs provided a selective advantage for species affiliated to the phylum including Acidobacteria, Verrucomicrobia and Planctomycetes while suppressing Proteobacteria and Actinobacteria.

  14. Prevalence of Plasmid-Mediated Quinolone Resistance Genes among Ciprofloxacin-Nonsusceptible Escherichia coli and Klebsiella pneumoniae Isolated from Blood Cultures in Korea

    Directory of Open Access Journals (Sweden)

    Hee Young Yang

    2014-01-01

    Full Text Available OBJECTIVES:To analyze the prevalence of plasmid-mediated quinolone resistance (PMQR determinants in ciprofloxacin-nonsusceptible Escherichia coli and Klebsiella pneumoniae isolated from patients at a tertiary care hospital in Korea.

  15. Occurrence of plasmid-mediated quinolone resistance and virulence genes in avian Escherichia coli isolates from Algeria.

    Science.gov (United States)

    Laarem, Meradi; Barguigua, Abouddihaj; Nayme, Kaotar; Akila, Abdi; Zerouali, Khalid; El Mdaghri, Naima; Timinouni, Mohammed

    2017-02-28

    The emergence and spread of quinolone-resistant Escherichia coli in poultry products puts consumers at risk of exposure to the strains of E. coli that resist antibiotic treatment. The objective of this study was to define the prevalence and virulence potential of poultry-associated nalidixic acid (NAL)-resistant E. coli in the Annaba city, Algeria. In total, 33 samples of retail chicken meat were purchased from various butcher shops and examined for bacterial contamination with NAL-resistant E. coli. These isolates were subjected to antimicrobial susceptibility testing and were also investigated for the presence of plasmid-mediated quinolone resistance (PMQR) genes and virulence genes using conventional polymerase chain reaction (PCR) and DNA sequencing. Phylogenetic grouping of the NAL-resistant E. coli isolates was determined by the conventional multiplex PCR method. Twenty-nine (87.8%) products yielded NAL-resistant E. coli. Antibiograms revealed that 96.55% of NAL-resistant E. coli isolates were multidrug resistant (MDR). Resistance was most frequently observed against sulfamethoxazole-trimethoprim (96.6%), tetracycline (96.6%), ciprofloxacin (72%), and amoxicillin (65.5%). Group A was the most prevalent phylogenetic group, followed by groups D, B1, and B2. The PMQR determinants were detected in three isolates with qnrB72 and qnrS1 type identified. Four (13.8%) isolates carried one of the Shiga toxin E. coli-associated genes stx1, stx2, and ehxA alleles. The high prevalence of NAL-resistant E. coli isolated from retail chicken meat with detection of MDR E. coli harboring Shiga toxin genes in this study gives a warning signal for possible occurrence of foodborne infections with failure in antibiotic treatment.

  16. [Investigation of plasmid-mediated quinolone resistance genes in quinolone-resistant Escherichia coli and Klebsiella spp. isolates from bloodstream infections].

    Science.gov (United States)

    Buruk, Celal Kurtuluş; Öztel Ocak, Hikmet; Bayramoğlu, Gülçin; Aydın, Faruk

    2016-04-01

    One of the treatment options of Escherichia coli and Klebsiella spp. infections which are the most common opportunistic pathogens of gram-negative sepsis is quinolones. Resistance to quinolones which act by disrupting DNA synthesis has been increasing. Horizontal transfer of plasmid-mediated quinolone resistance (PMQR) genes play an important role in the spread of resistance. The data about the prevalence of PMQR genes in our country is quite limited. The aim of this study was to investigate the presence of known PMQR genes namely qnrA, qnrB, qnrC, qnrS, qnrD, aac(6')-Ib-cr, qepA and oqxAB amongst quinolone-resistant E. coli and Klebsiella spp. strains isolated from blood cultures. One hundred twenty seven E.coli and 66 Klebsiella isolates detected as nalidixic acid- and/or ciprofloxacin-resistant by phenotypical methods, from 193 blood samples of 187 patients admitted to Karadeniz Technical University, Faculty of Medicine, Department of Medical Microbiology, Bacteriology Unit of Patient Service Laboratory between January 2012 to August 2013 were included in the study. The presence of PMQR genes were investigated by polymerase chain reaction (PCR) and for the detection of aac(6')-Ib-cr variants PCR-restriction fragment length polymorphism (PCR-RFLP) method was used. The positive bands were sequenced using the same primers, and aligned with formerly defined resistance gene sequences, and confirmed. In the study, 56.7% (72/127) of E.coli and 19.7% (13/66) of Klebsiella spp. isolates, with a total of 44% (85/193) of all the isolates were found to be phenotypically resistant to quinolones. Of the 13 resistant Klebsiella isolates, 11 were K.pneumoniae, and two were K.oxytoca. Extended-spectrum beta-lactamase (ESBL)-producing isolates showed higher resistance (50/80, 62.5%) to quinolones than the negative ones (35/113, 30.9%). The prevalence of quinolone resistance genes among resistant E. coli and Klebsiella spp. isolates was determined as qnrA, 1.4% and 15.4%; qnrB, 4

  17. Prevalence of plasmid-mediated quinolone resistance and aminoglycoside resistance determinants among carbapeneme non-susceptible Enterobacter cloacae.

    Directory of Open Access Journals (Sweden)

    Shifeng Huang

    Full Text Available BACKGROUND: Simultaneous resistance to aminoglycosides and fluoroquinolones in carbapeneme non-susceptible (CNS isolates will inevitably create problems. The present study was performed to characterize the prevalence of the plasmid-mediated quinolone resistance determinants (QRDs and aminoglycoside resistance determinants (ARDs among the CNS Enterobacter cloacae (E. cloacae isolates in a Chinese teaching hospital, and to acquire their molecular epidemiological characteristics. METHODS: The β-lactamases genes (including class A carbapenemase genes bla(KPC and bla(SME, metallo-β-lactamase genes (MBLs bla(IMP, bla(VIM and bla(NDM, and extended spectrum β-lactamases (ESBLs,bla(CTX-M, bla(TEM and bla(SHV, QRDs (including qnrA, qnrB, qnrS and aac(6'-Ib-cr and ARDs (including aac(6'-Ib, armA and rmtB of these 35 isolates were determined by PCR and sequenced bidirectionally. The clonal relatedness was investigated by pulsed-field gel electrophoresis (PFGE. RESULTS: Of the 35 isolates, 9 (25.7% harbored a carbapenemase gene; 23 (65.7% carried ESBLs; 24 (68.6% were QRD positive; and 27 (77.1% were ARD positive. Among the 5 bla(IMP-8 positive strains, 4 (80% contained both ESBL and QRD genes, and all the 5 (100% harbored ARD genes. Of the 23 ESBLs positive isolates, 6 (26.1% were carbapenemase positive, 14 (60.9% were QRD positive, and 18 (78.3% were ARD positive. PFGE revealed genetic diversity among the 35 isolates, indicating that the high prevalence of CNS E. cloacae isolates was not caused by clonal dissemination. CONCLUSION: QRD and ARD genes were highly prevalent among the CNS E. cloacae isolates. Multiple resistant genes were co-expressed in the same isolates. The CNS E. cloacae isolate co-expressing bla(NDM-1, bla(IMP-26, qnrA1 and qnrS1 was first reported.

  18. Detection of plasmid-mediated IMP-1 metallo-β-lactamase and quinolone resistance determinants in an ertapenem-resistant Enterobacter cloacae isolate

    Institute of Scientific and Technical Information of China (English)

    Li-rong CHEN; Hong-wei ZHOU; Jia-chang CAI; Rong ZHANG; Gong-xiang CHEN

    2009-01-01

    Objective: To investigate the mechanism of carbapenem resistance and the occurrence of plasmid-mediated quinolone resistance determinants qnr and aac(6')-Ib-cr in a clinical isolate of Enterobacter cloacae. Methods: An ertapenem-resistant E. cloacae ZY106, which was isolated from liquor puris of a female gastric cancer patient in a Chinese hospital, was investigated. Antibiotic susceptibilities were determined by agar dilution method. Conjugation experiments, isoelectric focusing, polymerase chain reaction (PCR), and DNA sequence analyses of plasmid-mediated carbapenemases and quinolone resistance determinants were preformed to confirm the genotype. Outer membrane proteins (OMPs) were examined by urea-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (Urea-SDS-PAGE). Results: Minimum inhibitory concentrations (MCs) of imipenem, mer-openem, and ertapenem for ZY106 were 2,4, and 16 ug/ml, respectively. Conjugation studies with Escherichia coli resulted in the transfer of significantly reduced carbapenem susceptibility. ZY106 produced IMP-1 metallo-p-lactamase and CTX-M-3 extended-spectrum P-lactamase, and E. coli transconjugant produced IMP-1. Plasmid-mediated quinolone resistance determinant qnrSI was detected in ZY106. Transfer of the qnrSI-encoding-plasmid into E. coli by conjugation resulted in intermediate resistance to ciprofloxacin in E. coli transconjugant. Urea-SDS-PAGE analysis of OMPs showed that ZY106 lacked an OMP of approximately 38 KDa. Conclusion: It is the first IMP-1-producing Enterobacteriaceae in China and the first report of a clinical isolate that harbors both blaIMP and qnrS genes as well. The blaIMP-1, blaCTX-M-3, and qnrSl are encoded at three different plasmids. IMP-1 combined with the loss of an OMP possibly resulted in ertapenem resistance and reduced imipenem and mero-penem susceptibility in E. cloacae.

  19. Plasmid-Mediated Quinolone Resistance in Escherichia coli Isolates from Wild Birds and Chickens in South Korea.

    Science.gov (United States)

    Oh, Jae-Young; Kwon, Yong-Kuk; Tamang, Migma Dorji; Jang, Hyung-Kwan; Jeong, Ok-Mi; Lee, Hee-Soo; Kang, Min-Su

    2016-01-01

    A total of 2,423 nonduplicate isolates of Escherichia coli recovered from wild birds (n=793) and chickens (n=1,630) in South Korea were investigated for plasmid-mediated quinolone resistance (PMQR) genes. Altogether, 56 isolates with PMQR genes were identified, including 25 (3.2%) from wild birds and 31 (1.9%) from chickens, which were further characterized using molecular methods. Among them, qnrS, aac(6')-Ib-cr, qnrB, and qepA genes were detected in 47 (1.9%), 6 (0.24%), 2 (0.08%), and 1 (0.04%) isolates, respectively. The most prevalent gene, qnrS, was identified in 21 (0.9%) and 26 (1.1%) isolates from wild birds and chickens, respectively. The qnrB gene was identified in two chicken isolates, which included qnrB19 and a novel qnrB44 gene. Plasmid isolation and Southern hybridization revealed that qnrS1 was located on a large (>200 kbp) plasmid. The spread of the PMQR genes was attributed to a combination of horizontal dissemination and clonal expansion. The horizontal dissemination of PMQR genes was mostly mediated by IncK plasmids. Molecular typing demonstrated that the majority of the PMQR-positive isolates were genetically diverse. Only one chicken isolate belonged to ST131, which harbored an additional CMY-2 gene. Our findings suggest that the wild birds could serve as reservoirs of PMQR genes and spread them over long distances through migration. To our knowledge, this is the first report of PMQR genes in Korean wild birds. This study also reports qnrS2, qnrB19, qnrB44, and qepA genes for the first time in animal E. coli isolates from South Korea.

  20. Prevalence and characterisation of plasmid-mediated quinolone resistance and mutations in the gyrase and topoisomerase IV genes among Shigella isolates from Henan, China, between 2001 and 2008.

    Science.gov (United States)

    Yang, Haiyan; Duan, Guangcai; Zhu, Jingyuan; Zhang, Weidong; Xi, Yuanlin; Fan, Qingtang

    2013-08-01

    A total of 293 Shigella isolates were isolated from patients with diarrhoea in four villages of Henan, China. This study investigated the prevalence of the plasmid-mediated quinolone resistance (PMQR) genes qnrA, qnrB, qnrS, qepA and aac(6')-Ib-cr and compared the polymorphic quinolone resistance-determining regions (QRDRs) of gyrA, gyrB, parC and parE. Of the isolates, 292 were found to be resistant to nalidixic acid and pipemidic acid, whereas 77 were resistant to ciprofloxacin (resistance rate of 26.3%). Resistance of the Shigella isolates to ciprofloxacin significantly increased from 2001 to 2008 (PShigella isolates are common in China. This study found that there was a significant increase in mutation rates of the QRDR and the resistant rates to ciprofloxacin. Other mechanisms may be present in the isolates that also contribute to their resistance to ciprofloxacin.

  1. Prevalence of Plasmid-Mediated Quinolone Resistance Genes among Extended-Spectrum β-Lactamase-Producing Klebsiella pneumoniae Human Isolates in Iran

    Directory of Open Access Journals (Sweden)

    Ehsaneh Shams

    2015-01-01

    Full Text Available The purpose of this study was to determine the prevalence and molecular characterization of plasmid-mediated quinolone resistance (PMQR genes (qnrA, qnrB, qnrS, aac(6′-Ib-cr, and qepA among ESBL-producing Klebsiella pneumoniae isolates in Kashan, Iran. A total of 185 K. pneumoniae isolates were tested for quinolone resistance and ESBL-producing using the disk diffusion method and double disk synergy (DDST confirmatory test. ESBL-producing strains were further evaluated for the blaCTX-M genes. The PCR method was used to show presence of plasmid-mediated quinolone resistance genes and the purified PCR products were sequenced. Eighty-seven ESBL-producing strains were identified by DDST confirmatory test and majority (70, 80.5% of which carried blaCTX-M genes including CTX-M-1 (60%, CTX-M-2 (42.9%, and CTX-M-9 (34.3%. Seventy-seven ESBL-producing K. pneumoniae isolates harbored PMQR genes, which mostly consisted of aac(6′-Ib-cr (70.1% and qnrB (46.0%, followed by qnrS (5.7%. Among the 77 PMQR-positive isolates, 27 (35.1% and 1 (1.3% carried 2 and 3 different PMQR genes, respectively. However, qnrA and qepA were not found in any isolate. Our results highlight high ESBL occurrence with CTX-M type and high frequency of plasmid-mediated quinolone resistance genes among ESBL-producing K. pneumoniae isolates in Kashan.

  2. Occurrence of Extended-Spectrum β-Lactamases, Plasmid-Mediated Quinolone Resistance, and Disinfectant Resistance Genes in Escherichia coli Isolated from Ready-To-Eat Meat Products

    DEFF Research Database (Denmark)

    Li, Lili; Ye, Lei; Kromann, Sofie

    2017-01-01

    There are growing concerns about the coselection of resistance against antibiotics and disinfectants in bacterial pathogens. The aim of this study was to characterize the antimicrobial susceptibility profiles, the prevalence of extended-spectrum β-lactamases (ESBLs), plasmid-mediated quinolone...... resistance genes (PMQRs), and quaternary ammonium compound resistance genes (QACs) in Escherichia coli isolated from ready-to-eat (RTE) meat products obtained in Guangzhou, China, and to determine whether these genes were colocalized in the isolates. A total of 64 E. coli isolates were obtained from 720 RTE...... meat samples. Multidrug resistance was observed in 70.3% of the isolates. A 100% of the isolates were resistant to benzalkonium chloride. Four types of β-lactamase genes were identified in the 16 ESBL-producing E. coli isolates: blaSHV (9.4%), blaTEM (7.8%), blaCTX-M-15 (1.6%), and blaCTX-M-9 (1...

  3. Plasmid-Mediated Quinolone Resistance (PMQR) Genes and Class 1 Integrons in Quinolone-Resistant Marine Bacteria and Clinical Isolates of Escherichia coli from an Aquacultural Area.

    Science.gov (United States)

    Tomova, Alexandra; Ivanova, Larisa; Buschmann, Alejandro H; Godfrey, Henry P; Cabello, Felipe C

    2017-06-23

    Antimicrobial usage in aquaculture selects for antimicrobial-resistant microorganisms in the marine environment. The relevance of this selection to terrestrial animal and human health is unclear. Quinolone-resistance genes qnrA, qnrB, and qnrS were chromosomally located in four randomly chosen quinolone-resistant marine bacteria isolated from an aquacultural area with heavy quinolone usage. In quinolone-resistant uropathogenic clinical isolates of Escherichia coli from a coastal area bordering the same aquacultural region, qnrA was chromosomally located in two E. coli isolates, while qnrB and qnrS were located in small molecular weight plasmids in two other E. coli isolates. Three quinolone-resistant marine bacteria and three quinolone-resistant E. coli contained class 1 integrons but without physical association with PMQR genes. In both marine bacteria and uropathogenic E. coli, class 1 integrons had similar co-linear structures, identical gene cassettes, and similarities in their flanking regions. In a Marinobacter sp. marine isolate and in one E. coli clinical isolate, sequences immediately upstream of the qnrS gene were homologous to comparable sequences of numerous plasmid-located qnrS genes while downstream sequences were different. The observed commonality of quinolone resistance genes and integrons suggests that aquacultural use of antimicrobials might facilitate horizontal gene transfer between bacteria in diverse ecological locations.

  4. Extended-Spectrum-Beta-Lactamases, AmpC Beta-Lactamases and Plasmid Mediated Quinolone Resistance in Klebsiella spp. from Companion Animals in Italy

    DEFF Research Database (Denmark)

    Donati, Valentina; Feltrin, Fabiola; Hendriksen, Rene S.

    2014-01-01

    We report the genetic characterization of 15 Klebsiella pneumoniae (KP) and 4 isolates of K. oxytoca (KO) from clinical cases in dogs and cats and showing extended-spectrum cephalosporin (ESC) resistance. Extended spectrum beta-lactamase (ESBL) and AmpC genes, plasmid-mediated quinolone resistance...... patterns observed, including two clusters of two (ST340) and four (ST101) indistinguishable isolates, respectively. All isolates harbored at least one ESBL or AmpC gene, all carried on transferable plasmids (IncR, IncFII, IncI1, IncN), and 16/19 were positive for PMQR genes (qnr family or aac(6')-Ib...... of multidrug-resistant Klebsiella with ESBL, AmpC and PMQR determinants, poses further and serious challenges in companion animal therapy and raise concerns for possible bidirectional transmission between pets and humans, especially at household level....

  5. Seawater is a reservoir of multi-resistant Escherichia coli, including strains hosting plasmid-mediated quinolones resistance and extended-spectrum beta-lactamases genes.

    Science.gov (United States)

    Alves, Marta S; Pereira, Anabela; Araújo, Susana M; Castro, Bruno B; Correia, António C M; Henriques, Isabel

    2014-01-01

    The aim of this study was to examine antibiotic resistance (AR) dissemination in coastal water, considering the contribution of different sources of fecal contamination. Samples were collected in Berlenga, an uninhabited island classified as Natural Reserve and visited by tourists for aquatic recreational activities. To achieve our aim, AR in Escherichia coli isolates from coastal water was compared to AR in isolates from two sources of fecal contamination: human-derived sewage and seagull feces. Isolation of E. coli was done on Chromocult agar. Based on genetic typing 414 strains were established. Distribution of E. coli phylogenetic groups was similar among isolates of all sources. Resistances to streptomycin, tetracycline, cephalothin, and amoxicillin were the most frequent. Higher rates of AR were found among seawater and feces isolates, except for last-line antibiotics used in human medicine. Multi-resistance rates in isolates from sewage and seagull feces (29 and 32%) were lower than in isolates from seawater (39%). Seawater AR profiles were similar to those from seagull feces and differed significantly from sewage AR profiles. Nucleotide sequences matching resistance genes bla TEM, sul1, sul2, tet(A), and tet(B), were present in isolates of all sources. Genes conferring resistance to 3rd generation cephalosporins were detected in seawater (bla CTX-M-1 and bla SHV-12) and seagull feces (bla CMY-2). Plasmid-mediated determinants of resistance to quinolones were found: qnrS1 in all sources and qnrB19 in seawater and seagull feces. Our results show that seawater is a relevant reservoir of AR and that seagulls are an efficient vehicle to spread human-associated bacteria and resistance genes. The E. coli resistome recaptured from Berlenga coastal water was mainly modulated by seagulls-derived fecal pollution. The repertoire of resistance genes covers antibiotics critically important for humans, a potential risk for human health.

  6. Seawater is a reservoir of multi-resistant Escherichia coli, including strains hosting plasmid-mediated quinolones resistance and extended-spectrum beta-lactamases genes

    Directory of Open Access Journals (Sweden)

    Marta S. Alves

    2014-08-01

    Full Text Available The aim of this study was to examine antibiotic resistance (AR dissemination in coastal water, considering the contribution of different sources of faecal contamination. Samples were collected in Berlenga, an uninhabited island classified as Natural Reserve and visited by tourists for aquatic recreational activities. To achieve our aim, AR in Escherichia coli isolates from coastal water was compared to AR in isolates from two sources of faecal contamination: human-derived sewage and seagull faeces. Isolation of E. coli was done on Chromocult agar. Based on genetic typing 414 strains were established. Distribution of E. coli phylogenetic groups was similar among isolates of all sources. Resistances to streptomycin, tetracycline, cephalothin and amoxicillin were the most frequent. Higher rates of AR were found among seawater and faeces isolates, except for last-line antibiotics used in human medicine. Multi-resistance rates in isolates from sewage and seagull faeces (29% and 32% were lower than in isolates from seawater (39%. Seawater AR profiles were similar to those from seagull faeces and differed significantly from sewage AR profiles. Nucleotide sequences matching resistance genes blaTEM, sul1, sul2, tet(A and tet(B, were present in isolates of all sources. Genes conferring resistance to 3rd generation cephalosporins were detected in seawater (blaCTX-M-1 and blaSHV-12 and seagull faeces (blaCMY-2. Plasmid-mediated determinants of resistance to quinolones were found: qnrS1 in all sources and qnrB19 in seawater and seagull faeces. Our results show that seawater is a relevant reservoir of AR and that seagulls are an efficient vehicle to spread human-associated bacteria and resistance genes. The E. coli resistome recaptured from Berlenga coastal water was mainly modulated by seagulls-derived faecal pollution. The repertoire of resistance genes covers antibiotics critically important for humans, a potential risk for human health.

  7. High Prevalence of β-lactamase and Plasmid-Mediated Quinolone Resistance Genes in Extended-Spectrum Cephalosporin-Resistant Escherichia coli from Dogs in Shaanxi, China

    Science.gov (United States)

    Liu, Xiaoqiang; Liu, Haixia; Li, Yinqian; Hao, Caiju

    2016-01-01

    Objective: The aim of this study was to investigate the occurrence and molecular characterization of extended-spectrum β-lactamases (ESBL), plasmid-mediated AmpC β-lactamase (pAmpC) and carbapenemases as well as plasmid-mediated quinolone-resistant (PMQR) among extended-spectrum cephalosporin-resistant (ESC-R) Escherichia coli from dogs in Shaanxi province in China. Methods: A total of 40 ESC-R Escherichia coli selected from 165 Extraintestinal pathogenic E. coli (ExPEC) isolated from dogs were screened and characterized for the genes encoding for the ESBLs, pAmpC, carbapenemases and PMQR genes by PCR and sequencing. Phylogenetic groups, virulence gene profiles and multilocus sequence typing (MLST) were used to investigate the genetic background of the ESC-R E. coli isolates. Results: Among 40 ESC-R E. coli, the predominant β-lactamase gene was blaCTX−Ms (n = 35), and followed by blaTEM−1 (n = 31), blaSHV−12 (n = 14), blaOXA−48 (n = 8), blaTEM−30 (n = 4), blaCMY−2 (n = 3) and blaDHA−1 (n = 2). The most common specific blaCTX−M gene subtype was blaCTX−M−15 (n = 31), and followed by blaCTX−M−123 (n = 14), blaCTX−M−1 (n = 10), blaCTX−M−14 (n = 10) and blaCTX−M−9 (n = 7). PMQR genes were detected in 32 (80%) isolates, and the predominant PMQR gene was aac(6′)-Ib-cr (n = 26), followed by qnrS (n = 12), qnrD (n = 9), qnrB (n = 8), qepA (n = 4), and all PMQR genes were detected in co-existence with β-lactamase genes. traT (n = 34) and fimH (n = 32) were the most prevalent virulence genes, and virulence genes fimH, iutA, fyuA, malX, iha, and sat were more prevalent in phylogenetic group B2. The 40 ESC-R isolates analyzed were assigned to 22 sequence types (STs), and the clonal lineages ST131 (n = 10) and ST10 (n = 9) were the predominant STs. Conclusion: High prevalence of β-lantamases and PMQR genes were detected among ESC-R E. coli from companion animals. This is also the first description of the co-existence of six

  8. High Prevalence of β-lactamase and Plasmid-mediated Quinolone Resistance Genes in Extended-spectrum Cephalosporin-resistant Escherichia coli from Dogs in Shaanxi, China

    Directory of Open Access Journals (Sweden)

    Xiaoqiang Liu

    2016-11-01

    Full Text Available Objective: The aim of this study was to investigate the occurrence and molecular characterization of extended-spectrum β-lactamases (ESBL, plasmid-mediated AmpC β-lactamase (pAmpC and carbapenemases as well as plasmid-mediated quinolone-resistant (PMQR among extended-spectrum cephalosporin-resistant (ESC-R Escherichia coli from dogs in Shaanxi province in China.Methods: A total of 40 ESC-R Escherichia coli selected from 165 Extraintestinal pathogenic E. coli (ExPEC isolated from dogs were screened and characterized for the genes encoding for the ESBLs, pAmpC, carbapenemases and PMQR genes by PCR and sequencing. Phylogenetic groups, virulence gene profiles and multilocus sequence typing (MLST were used to investigate the genetic background of the ESC-R E. coli isolates. Results: Among 40 ESC-R E. coli, the predominant β-lactamase gene was blaCTX-Ms (n=35, and followed by blaTEM-1 (n=31, blaSHV-12 (n=14, blaOXA-48 (n=8, blaTEM-30 (n=4, blaCMY-2 (n=3 and blaDHA-1 (n=2. The most common specific blaCTX-M gene subtype was blaCTX-M-15 (n=31, and followed by blaCTX-M-123 (n=14, blaCTX-M-1 (n=10, blaCTX-M-14 (n=10 and blaCTX-M-9 (n=7. PMQR genes were detected in 32 (80% isolates, and the predominant PMQR gene was aac(6'-Ib-cr (n=26, followed by qnrS (n=12, qnrD (n=9, qnrB (n=8, qepA (n=4, and all PMQR genes were detected in co-existence with β-lactamase genes. traT (n=34 and fimH (n=32 were the most prevalent virulence genes, and virulence genes fimH, iutA, fyuA, malX, iha and sat were more prevalent in phylogenetic group B2. The 40 ESC-R isolates analyzed were assigned to 22 sequence types (STs, and the clonal lineages ST131 (n=10 and ST10 (n=9 were the predominant STs. Conclusion: High prevalence of β-lantamases and PMQR genes were detected among ESC-R E. coli from companion animals. This is also the first description of the co-existence of six β-lantamase genes and five PMQR genes in one E. coli isolate. Moreover, ten ST131 clones harboring CTX

  9. Identification of plasmid-mediated quinolone resistance qnr genes in multidrug-resistant Gram-negative bacteria from hospital wastewaters and receiving waters in the Jinan area, China.

    Science.gov (United States)

    Xia, Ruirui; Ren, Ye; Xu, Hai

    2013-12-01

    We investigated the prevalence of plasmid-mediated quinolone resistance (PMQR) qnr genes by the polymerase chain reaction (PCR) in antibiotic-resistant bacteria isolates collected from aquatic environments in Jinan during 2 years (2008.3-2009.11). Genes were identified to variant level by PCR restriction fragment length polymorphism analysis or sequencing. qnrA1, qnrB2, qnrB4, qnrB6, qnrB9, qnrS1, and the new qnrB variant qnrB26 were detected in 31 strains from six genera (Klebsiella spp., Escherichia coli, Enterobacter spp., Proteus spp., Shigella spp., and Citrobacter spp.), four of which contained double qnr genes. Other PMQR genes, aac(6')-Ib-cr and qepA, were found in 12 (38.7%) and 5 (16.1%) of 31 isolates, respectively; while qepA was found in Shigella spp. for the first time. Eight types of β-lactamase genes and eight other types of resistance genes were also present in the 31 qnr-positive isolates. The detection rate for five β-lactamase genes (blaTEM, blaCTX, ampR, blaDHA, and blaSHV) was >45%. Class 1 integrons and complex class 1 integrons were prevalent in these strains, which contained 15 different gene cassette arrays and 5 different insertion sequence common region 1 (ISCR1)-mediated downstream structures. qnrA1, qnrB2, and qnrB6 were present in three ISCR1-mediated downstream structures: qnrA1-ampR, sapA-like-qnrB2, and sdr-qnrB6. We also analyzed the horizontal transferability of PMQR genes and other resistance determinants. The qnr genes and some integrons and resistance genes from 18 (58.1%) of the 31 qnr-positive strains could be transferred to E. coli J53 Azi(R) or E. coli DH5α recipient strains using conjugation or transformation methods. The results showed that a high number of qnr genes were associated with other resistance genes in aquatic environments in Jinan. This suggests that we should avoid over-using antibiotics and monitor aquatic environments to control the spread of antibiotic resistance genes.

  10. Characterization of Plasmid-Mediated Quinolone Resistance Determinants in High-Level Quinolone-Resistant Enterobacteriaceae Isolates from the Community: First Report of qnrD Gene in Algeria.

    Science.gov (United States)

    Yanat, Betitera; Machuca, Jesús; Díaz-De-Alba, Paula; Mezhoud, Halima; Touati, Abdelaziz; Pascual, Álvaro; Rodríguez-Martínez, José-Manuel

    2017-01-01

    The objective was to assess the prevalence of plasmid-mediated quinolone resistance (PMQR)-producing isolates in a collection of quinolone-resistant Enterobacteriaceae of community origin isolated in Bejaia, Algeria. A total of 141 nalidixic acid-resistant Enterobacteriaceae community isolates were collected in Bejaia (Northern Algeria) and screened for PMQR genes using polymerase chain reaction (PCR). For PMQR-positive strains, antimicrobial susceptibility testing was performed by broth microdilution and disk diffusion. Mutations in the quinolone resistance-determining regions of the target genes, gyrA and parC, were detected with a PCR-based method and sequencing. Southern blotting, conjugation and transformation assays and molecular typing by pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing were also performed. The prevalence of PMQR-producing Enterobacteriaceae isolates was 13.5% (19/141); 11 of these isolates produced Aac(6')-Ib-cr and 8 were qnr-positive (4 qnrB1-like, 2 qnrS1-like, and 2 qnrD1-like), including the association with aac(6')-Ib-cr gene in three cases. PMQR gene transfer by conjugation was successful in 6 of 19 isolates tested. PFGE revealed that most of the PMQR-positive Escherichia coli isolates were unrelated, except for two groups comprising two and four isolates, respectively, including the virulent multidrug-resistant clone E. coli ST131 that were clonally related. Our findings indicate that PMQR determinants are prevalent in Enterobacteriaceae isolates from the community studied. We describe the first report of the qnrD gene in Algeria.

  11. Progress in research of plasmid-mediated quinolone resistance gene of enterobacteria%肠杆菌科细菌质粒介导的喹诺酮耐药基因研究进展

    Institute of Scientific and Technical Information of China (English)

    符浩; 夏兴; 陈代杰

    2011-01-01

    继首个质粒介导的喹诺酮耐药基因qnrAl之后,qnrB,qnrS,qnrC和qnrD等其他一些类似基因也相继被发现.另 外,两种质粒介导的喹诺酮耐药机制,即外排泵QepA和OqxAB以及氨基糖苷甲基转移酶Aac(6’)-Ib-cr陆续被报道.本文综述肠杆菌科细菌质粒介导的喹诺酮耐药基因研究进展.%Since the first plasmid-mediated quinolone antibiotics resistance gene (PMQR, currently named qnrAl) was reported, some other genes such as qnrB, qnrS, qnrC and qnrD have also been characterized. In addition, two other plasmid-mediated resistance mechanisms: the modification of quinolones with a piperazinyl substituent by the acetyltransferase, Aac (6') -Ib-cr, and active efflux by QepA and OqxAB have also been reported. This review describes the progress in research of plasmid-mediated quinolone resistance gene of enterobacteria.

  12. Extended spectrum β-lactamase and plasmid mediated quinolone resistance in Escherichia coli fecal isolates from healthy companion animals in Algeria.

    Science.gov (United States)

    Yousfi, Massilia; Mairi, Assia; Touati, Abdelaziz; Hassissene, Lila; Brasme, Lucien; Guillard, Thomas; De Champs, Christophe

    2016-07-01

    The aim of this study was to evaluate the rate of fecal carriage of Escherichia coli strains producing Extended-spectrum β-lactamases (ESBLs) and plasmid-mediated quinolone resistance (PMQR) isolated from healthy pets (dogs and cats) in Algeria. Fecal samples from 171 healthy pets (102 dogs and 69 cats) in one veterinary practice and private owners were included. After isolates identification, antibiotic susceptibility was determined by disk diffusion procedure. ESBL were detected by combination disk tests. PCR and sequencing were used to characterize genes encoding ESBLs and PMQR. Transfer of ESBL and PMQR genes was assessed by conjugation experiments. Phylogenetic groups of E. coli were determined by PCR. Of the 171 animals, 20 carried an ESBL producing E. coli giving a prevalence of ESBL fecal carriage of 11.7%. All isolates were susceptible to carbapenems, cefoxitin, piperacillin-tazobactam, amikacin and fosfomycine. For the rest of the tested β-lactams, susceptibility rates ranged from 35% to 70% for cefepime and amoxicillin-clavulanic acid respectively. Concerning the non-beta-lactams antibiotics, the rates of susceptibility ranged between 5% to trimethoprim and 95% for chloramphenicol. The beta-lactamase genes identified in E. coli isolates were blaCTX-M-15, blaCTX-M-1, blaSHV-12 and blaTEM-1. The PMQR determinants aac(6')-Ib-cr, qnrS1 and qnrB5 genes were identified in 15 isolates. Transconjugants were obtained for two isolates. Phylogenetic analysis showed that E. coli isolates belong to commensal phylogroups of A and B1. We reported here for the first time in Algeria ESBL and PMQR-producing E. coli in healthy cats and dogs.

  13. Extended-spectrum-beta-lactamases, AmpC beta-lactamases and plasmid mediated quinolone resistance in klebsiella spp. from companion animals in Italy.

    Directory of Open Access Journals (Sweden)

    Valentina Donati

    Full Text Available We report the genetic characterization of 15 Klebsiella pneumoniae (KP and 4 isolates of K. oxytoca (KO from clinical cases in dogs and cats and showing extended-spectrum cephalosporin (ESC resistance. Extended spectrum beta-lactamase (ESBL and AmpC genes, plasmid-mediated quinolone resistance (PMQR and co-resistances were investigated. Among KP isolates, ST101 clone was predominant (8/15, 53%, followed by ST15 (4/15, 27%. ST11 and ST340, belonging to Clonal Complex (CC11, were detected in 2012 (3/15, 20%. MLST on KP isolates corresponded well with PFGE results, with 11 different PFGE patterns observed, including two clusters of two (ST340 and four (ST101 indistinguishable isolates, respectively. All isolates harbored at least one ESBL or AmpC gene, all carried on transferable plasmids (IncR, IncFII, IncI1, IncN, and 16/19 were positive for PMQR genes (qnr family or aac(6'-Ib-cr. The most frequent ESBL was CTX-M-15 (11/19, 58%, detected in all KP ST101, in one KP ST15 and in both KP ST340. blaCTX-M-15 was carried on IncR plasmids in all but one KP isolate. All KP ST15 isolates harbored different ESC resistance genes and different plasmids, and presented the non-transferable blaSHV-28 gene, in association with blaCTX-M-15, blaCTX-M-1 (on IncR, or on IncN, blaSHV-2a (on IncR or blaCMY-2 genes (on IncI1. KO isolates were positive for blaCTX-M-9 gene (on IncHI2, or for the blaSHV-12 and blaDHA-1 genes (on IncL/M. They were all positive for qnr genes, and one also for the aac(6'-Ib-cr gene. All Klebsiella isolates showed multiresistance towards aminoglycosides, sulfonamides, tetracyclines, trimethoprim and amphenicols, mediated by strA/B, aadA2, aadB, ant (2"-Ia, aac(6'-Ib, sul, tet, dfr and cat genes in various combinations. The emergence in pets of multidrug-resistant Klebsiella with ESBL, AmpC and PMQR determinants, poses further and serious challenges in companion animal therapy and raise concerns for possible bi-directional transmission between

  14. Characterization of plasmid-mediated quinolone resistance (PMQR genes in extended-spectrum β-lactamase-producing Enterobacteriaceae pediatric clinical isolates in Mexico.

    Directory of Open Access Journals (Sweden)

    Jesus Silva-Sánchez

    Full Text Available This work describes the characterization of plasmid-mediated quinolone-resistance (PMQR genes from a multicenter study of ESBL-producing Enterobacteriaceae pediatric clinical isolates in Mexico. The PMQR gene-positive isolates were characterized with respect to ESBLs, and mutations in the GyrA and ParC proteins were determined. The phylogenetic relationship was established by PFGE and the transfer of PMQR genes was determined by mating assays. The prevalence of the PMQR genes was 32.1%, and the rate of qnr-positive isolates was 15.1%; 93.3% of the latter were qnrB and 6.4% were qnrA1. The distribution of isolates in terms of bacterial species was as follows: 23.5% (4/17 corresponded to E. cloacae, 13.7% (7/51 to K. pneumoniae, and 13.6% (6/44 to E. coli. In addition, the prevalence of aac(6'-Ib-cr and qepA was 15.1% and 1.7%, respectively. The molecular characteristics of qnr- and qepA-positive isolates pointed to extended-spectrum β-lactamase (ESBL CTX-M-15 as the most prevalent one (70.5%, and to SHV-12 in the case of aac(6'-Ib-cr-positive isolates. GyrA mutations at codons Ser-83 and Asp-87, and ParC mutations at codons Ser-80 were observed in 41.1% and 35.2% of the qnr-positive isolates, respectively. The analysis of the transconjugants revealed a co-transmission of bla(CTX-M-15 with the qnrB alleles. In general, the prevalence of PMQR genes (qnr and aac(6'-Ib-cr presented in this work was much lower in the pediatric isolates, in comparison to the adult isolates in Mexico. Also, ESBL CTX-M-15 was the main ESBL identified in the pediatric isolates, whereas in the adult ones, ESBLs corresponded to the CTX-M and the SHV families. In comparison with other studies, among the PMQR-genes identified in this study, the qnrB-alleles and the aac(6'-Ib-cr gene were the most prevalent, whereas the qnrS1, qnrA1 and qnrB-like alleles were the most prevalent in China and Uruguay.

  15. Research of quinolones plasmid-mediated resistance mechanisms and countermeasure%喹诺酮类药物的质粒介导耐药机制及其对抗防御措施研究

    Institute of Scientific and Technical Information of China (English)

    李建华; 宋丰贵

    2008-01-01

    随着喹诺酮类抗菌药物在临床上的广泛应用,细菌对喹诺酮类药物的耐药性上升迅速.研究发现,细菌对喹诺酮类药物耐药的机制主要为靶位改变及主动外排,两者均为染色体介导.近年发现与两者完全不同的质粒介导耐药机制,且越来越多的临床菌株得以证实.本文主要对喹诺酮类药物的质粒介导的耐药机制及如何采取相应对抗防御措施进行综述.%Along with widespread application of quinolones antibiotics in clinic,quinolones resistanceof bacteria has rapidly risen. It is discovered that mechanisms of quinolones resistance of bacteria are mainlyinvolves change of target site and initiative excretion, which are both mediated by chromosome. In recentyears,plasmid-mediated drug resistance mechanism has been discovered,which is completely different fromthem. More and more clinical bacteria strains have been confirmed. The paper summarizes plasmid-mediatedquinolones resistance mechanisms and measures taken.

  16. Identification of plasmid-mediated quinolone resistance genes qnrA1, qnrB1 and aac(6′-1b-cr in a multiple drug-resistant isolate of Klebsiella pneumoniae from Chennai

    Directory of Open Access Journals (Sweden)

    H Magesh

    2011-01-01

    Full Text Available Purpose: Resistance to fluoroquinolones, a commonly prescribed antimicrobial for Gram-negative and Gram-positive microorganisms, is of importance in therapy. The purpose of this study was to screen for the presence of Plasmid-Mediated Quinolone Resistance (PMQR determinants in clinical isolates of Klebsiella pneumoniae. Materials and Methods: Extended-Spectrum Beta-Lactamase (ESBL isolates of K. pneumoniae collected during October 2009 were screened by the antimicrobial susceptibility test. The plasmids from these isolates were analysed by specific Polymerase chain Reaction (PCR for qnrA, qnrB and aac(6′-1b. The amplified products were sequenced to confirm the allele. Results: Our analysis showed that 61% out of the 23 ESBL K. pneumoniae isolates were resistant to ciprofloxacin and 56% to levofloxacin. The PMQR was demonstrated by transforming the plasmids from two isolates P12 and P13 into E. coli JM109. The PMQR gene qnrA was found in 16 isolates and qnrB in 11 isolates. The plasmid pKNMGR13 which conferred an minimum inhibitory concentration (MIC of more than 240 ΅g/ml in sensitive E. coli was found to harbour the qnrA1 and qnrB1 allele. Furthermore, the gene aac(6′-1b-cr encoding a variant aminoglycoside 6′-N Acetyl transferase which confers resistance to fluoroquinolones was found in the same plasmid. Conclusions: Our report shows the prevalence of PMQR mediated by qnrA and qnrB in multidrug-resistant K. pneumoniae isolates from Chennai. A multidrug-resistant plasmid conferring high resistance to ciprofloxacin was found to harbour another PMQR gene, aac(6′-1b-cr mutant gene. This is the first report screening for PMQR in K. pneumoniae isolates from India.

  17. High Prevalence of Plasmid-Mediated Quinolone Resistance and IncQ Plasmids Carrying qnrS2 Gene in Bacteria from Rivers near Hospitals and Aquaculture in China.

    Directory of Open Access Journals (Sweden)

    Yanping Wen

    Full Text Available Effluents from hospital and aquaculture are considered important sources of quinolone resistance. However, little information is available on the impact of this effluent on nearby rivers. In this study, 188 ciprofloxacin-resistant bacterial isolates obtained from rivers near hospitals and aquaculture were screened for plasmid-mediated quinolone resistance (PMQR genes. Species identification, antibiotic susceptibility testing, and PMQR gene transferability assessment were conducted for PMQR-positive bacteria. Representative qnrS2-encoding plasmids were subsequently sequenced using a primer-walking approach. In total, 44 isolates (23.4% were positive for qnr genes (16 qnrB2, 3 qnrS1, and 25 qnrS2 and 32 isolates (17.0% were positive for aac(6'-Ib-cr. Other PMQR genes were not detected. The qnrB2 and aac(6'-Ib-cr genes had a higher prevalence in aquaculture samples than in hospital samples, and were significantly associated with Enterobacteriaceae (p < 0.05. In contrast, the prevalence of qnrS2 was not site-related, but was significantly associated with Aeromonas spp. (p < 0.05. All PMQR isolates were resistant to three or more classes of antibiotics. Eleven qnrS2-harboring plasmids from Aeromonas spp., including a novel conjugative plasmid pHP18, were selected for sequencing. These plasmids were small in size (6,388-16,197 bp and belonged to the IncQ or IncU plasmid family, with qnrS2 being part of a mobile insertion cassette. Taken together, our findings suggest that aquaculture is a possible source for aac(6'-Ib-cr and qnrB2 dissemination, and demonstrate the ubiquity of qnrS2 in aquatic environments. Finally, Aeromonas spp. served as vectors for qnrS2 with the help of IncQ-type plasmids.

  18. 质粒介导细菌对喹诺酮类抗菌药物的耐药机制%Plasmid Mediated Mechanism of Bacterial Resistance to Quinolones

    Institute of Scientific and Technical Information of China (English)

    马晓波; 宋秀宇

    2009-01-01

    喹诺酮类抗菌药物是临床最为常用的抗菌药物之一,但其耐药的问题也日益严重。细菌对喹诺酮类抗菌药物的耐药机制有:(1)染色体介导的耐药,包括药物作用靶位的改变(特别是喹诺酮耐药决定区(QRDR)的基因突变]、外膜通透性的下降、主动外排作用。(2)质粒介导的耐药。质粒介导的喹诺酮类耐药(plasmid mediated quinolone resistance,PMQR)由qnr(quinolone resistance,后来更名为qnrA)、aac-(6’)-Ⅰb-cr及qepA(quinolone efflux proteinA)等参与。PMQR机制的发现使人们对细菌耐喹诺酮类药物的机制有了新的认识。

  19. Plasmid-mediated tetracycline resistance in Haemophilus ducreyi.

    OpenAIRE

    Albritton, W L; Maclean, I W; Slaney, L A; Ronald, A. R.; Deneer, H G

    1984-01-01

    Clinical isolates of Haemophilus ducreyi were shown to be resistant to tetracycline. Resistance was associated in some strains with a 30-megadalton plasmid capable of transferring resistance in conjugative matings with other strains of H. ducreyi and other species of Haemophilus. Restriction endonuclease digestion patterns suggest a relationship between H. ducreyi plasmids and other tetracycline resistance plasmids in Haemophilus. The presence of plasmid-mediated resistance to the tetracyclin...

  20. International collaborative study on the occurrence of plasmid mediated quinolone resisitance in Salmonella enterica en Escherichia coli isolated from animals, humans, food and the environment in 13 European countries.

    NARCIS (Netherlands)

    Veldman, K.T.; Cavaco, L.M.; Mevius, D.J.; Battisti, A.; Botteldoorn, N.; Bruneau, M.; Cerny, T.; Franco, A.; Frutos Escobar, De C.; Guerra, B.; Gutierrez, M.; Hopkins, K.; Myllyniemi, A.L.; Perrin-Guyomard, A.; Schroeter, A.; Sunde, M.; Wasyl, D.; Aarestrup, F.M.

    2011-01-01

    Objectives This study was initiated to collect retrospective information on the occurrence of plasmid-mediated quinolone resistance (PMQR) in Salmonella enterica and Escherichia coli isolates in Europe and to identify the responsible genes. Methods Databases of national reference laboratories contai

  1. Distribution characteristics and drug resistant analysis of plasmid-mediated quinolone drug resistant gene qnr of Klebsiella pneumoniae isolates separated from sputum samples in our hospital%痰标本中质粒介导喹诺酮耐药基因qnr在肺炎克雷伯菌中的分布特征及耐药分析

    Institute of Scientific and Technical Information of China (English)

    菅凌燕; 何晓静; 于莹

    2012-01-01

    目的:了解从痰标本中分离出的肺炎克雷伯菌对16种抗茵药物的耐药性,以及研究由质粒介导的喹诺酮类耐药基因qnr在肺炎克雷伯菌中的存在情况.方法:用PCR及直接测序的方法对135株肺炎克雷伯菌进行qnr基因检测,并用K-B纸片法检测其对16种抗茵药物的体外抗菌活性.另外,用琼脂平皿二倍稀释法检测阳性菌株对左氧氟沙星的MIC值.结果:135株肺炎克雷伯菌中,9株(6.6%)检出qnr基因.阳性菌株均对亚胺培南敏感且对多种抗生素耐药,其中2株qnr阳性菌株对左氧氟沙星敏感.结论:肺炎克雷伯菌中存在质粒介导喹诺酮类耐药基因qnr基因,qnr阳性菌株呈现多重耐药.临床工作中,应加强对耐药基因的监测,降低细菌耐药的发生.%OBJECTIVE To explore the drug resistant characteristics to 16 kinds of antibiotics and the distribution of plasmid-mediated quinolone drug resistant gene qnr of Klebsiella pneumoniae isolates separated from sputum samples. METHODS By using PCR and direct sequencing method, the gene qnr of Klebsiella pneumoniae was detected. Then, the antibacterial activities of 16 kinds of antibiotics on Klebsiella pneumoniae isolates in vitro were studied. Finally, was detected the MIC value of levofloxacin on gene qnr positive Klebsiella pneumoniae isolates with agar plate two-fold dilution method. RESULTS Among all 135 Klebsiella pneumoniae isolates, 9 Klebsiella pneumoniae isolates was determined with gene qnr. These isolates were all sensitive to imipenem and resistant to the other kinds of antibiotics. There were also 2 Klebsiella pneumoniae isolates sensitive to levofloxacin. CONCLUSION There are plasmid-mediated quinolone drug resistant gene qnr in our hospital. Qnr positive i-solates were multi-drug resistant. In clinic, we should pay attention to monitor on drug resistant genes and decrease the frequencies of drug resistant.

  2. Occurrence of the Plasmid-Mediated Fluoroquinolone Resistance qepA1 Gene in Two Clonal Clinical Isolates of CTX-M-15-Producing Escherichia coli from Algeria.

    Science.gov (United States)

    Yanat, Betitera; Dali Yahia, Radia; Yazi, Leila; Machuca, Jesús; Díaz-De-Alba, Paula; Touati, Abdelaziz; Pascual, Álvaro; Rodríguez-Martínez, José-Manuel

    2016-10-13

    QepA is a plasmid-mediated quinolone resistance determinant of low prevalence described worldwide, mainly in Enterobacteriaceae. This study describes, for the first time in Algeria, two clonally related, QepA-producing Escherichia coli clinical isolates positive for CTX-M-15. The clonal spread of these multidrug-resistant isolates is a major public health concern.

  3. First characterisation of plasmid-mediated quinolone resistance-qnrS1 co-expressed bla CTX-M-15 and bla DHA-1 genes in clinical strain of Morganella morganii recovered from a Tunisian Intensive Care Unit

    Directory of Open Access Journals (Sweden)

    S Mahrouki

    2012-01-01

    Full Text Available Purpose: Aim of this study was to show the emergence of the qnr genes among fluoroquinolone-resistant, AMPC and ESBL (extended-spectrum-beta-lactamase co-producing Morganella morganii isolate. Materials and Methods: A multi resistant Morganella morganii SM12012 isolate was recovered from pus from a patient hospitalized in the intensive care unit at the Military hospital, Tunisia. Antibiotic susceptibility was tested with the agar disk diffusion method according to Clinical and Laboratory Standards Institute guidelines. ESBLs were detected using a standard double-disk synergy test. The characterization of beta-lactamases and associated resistance genes were performed by isoelectric focusing, polymerase chain reaction and nucleotide sequencing. Results: The antimicrobial susceptibility testing showed the high resistance to penicillins, cephalosporins (MICs: 64-512 μg/ml and fluoroquinolones (MICs: 32-512 μg/ml. But M. morganii SM12012 isolate remained susceptible to carbapenems (MICs: 4-<0.25 μg/ml. The double-disk synergy test confirmed the phenotype of extended-spectrum β-lactamases (ESBLs. Three identical β-lactamases with pI values of 6.5, 7.8 and superior to 8.6 were detected after isoelectric focusing analysis. These β-lactamases genes can be successfully transferred by the conjugative plasmid. Molecular analysis demonstrated the co-production of bla DHA-1, bla CTX-M-15 and qnrS1 genes on the same plasmid. The detection of an associated chromosomal quinolone resistance revealed the presence of a parC mutation at codon 80 (Ser80-lle80. Conclusion: This is the first report in Tunisia of nosocomial infection due to the production of CTX-M-15 and DHA-1 β-lactamases in M. morganii isolate with the association of quinolone plasmid resistance. The incidence of these strains invites continuous monitoring of such multidrug-resistant strains and the further study of their epidemiologic evolution.

  4. International collaborative study on the occurrence of plasmid-mediated quinolone resistance in Salmonella enterica and Escherichia coli isolated from animals, humans, food and the environment in 13 European countries

    DEFF Research Database (Denmark)

    Veldman, Kees; Cavaco, Lina; Mevius, Dik

    2011-01-01

    containing MIC values for Salmonella and E. coli isolated between 1994 and 2009 in animals, humans, food and the environment from 13 European countries were screened for isolates exhibiting a defined quinolone resistance phenotype, i.e. reduced susceptibility to fluoroquinolones and nalidixic acid. PCR....... In Salmonella, qnrS1 (n = 125) and variants of qnrB (n = 138) were frequently identified, whereas qnrA1 (n = 3) and aac(6')-1b-cr (n = 3) were rarely found. qnrD was detected in 22 Salmonella isolates obtained from humans and animals. In E. coli, qnrS1 was identified in 19 isolates and qnrB19 was found in one...

  5. Plasmid mediated antibiotic resistance in isolated bacteria from burned patients.

    Science.gov (United States)

    Beige, Fahimeh; Baseri Salehi, Majid; Bahador, Nima; Mobasherzadeh, Sina

    2015-01-01

    Nowadays, the treatment of burned patients is difficult because of the high frequency of infection with antibiotic resistance bacteria. This study was conducted to evaluate the level of antibiotic resistance in Gram-negative bacteria and its relation with the existence of plasmid. The samples were collected from two hundred twenty hospitalized burned patients in Isfahan burn hospital during a three-month period (March 2012 to June 2012). The samples were isolated and the Gram-negative bacteria were identified using phenotypic method and API 20E System. Antibiotic susceptibility and plasmid profile were determined by standard Agar disc diffusion and plasmid spin column extraction methods. Totally 117 Gram-negative bacteria were isolated, the most common were Pseudomonas aerugionsa (37.6%), P. fluorescens (25.6%), Acinetobacter baumanii (20/5%) and Klebsiella pneumoniae (7.6%), respectively. The isolates showed high frequency of antibiotic resistance against ceftazidime and co-amoxiclave (100%) and low frequency of antibiotic resistance against amikacin with (70%).The results indicated that 60% of the isolates harboured plasmid. On the other hand, the patients infected with A. baumanii and P. aeruginosa were cured (with 60% frequency) whereas, those infected with P. fluorescens were not cured. Hence, probably antibiotic resistance markers of A. baumanii and P. aeruginosa are plasmid mediated; however, P. fluorescens is chromosomally mediated. Based on our findings, P. aerugionsa is a major causative agent of wound infections and amikacin could be considered as a more effective antibiotic for treatment of the burned patients.

  6. [Quinolones. Nowadays perspectives and mechanisms of resistance].

    Science.gov (United States)

    Álvarez-Hernández, Diego Abelardo; Garza-Mayén, Gilda Sofía; Vázquez-López, Rosalno

    2015-10-01

    Quinolones are a family of synthetic broad-spectrum antimicrobial drugs whose target is the synthesis of DNA. They directly inhibit DNA replication by interacting with two enzymes; DNA gyrase and topoisomerase IV. They have been widely used for the treatment of several community and hospital acquired infections, in the food processing industry and in the agricultural field, making the increasing incidence of quinolone resistance a frequent problem associated with constant exposition to diverse microorganisms. Resistance may be achieved by three non-exclusive mechanisms; through chromosomic mutations in the Quinolone Resistance-Determining Regions of DNA gyrase and topoisomerase IV, by reducing the intracytoplasmic concentrations of quinolones actively or passively and by Plasmid-Mediated Quinolones-Resistance genes, [Qnr determinant genes of resistance to quinolones, variant gene of the aminoglycoside acetyltransferase (AAC(6')-Ib-c)] and encoding genes of efflux pumps (qepA and oqxAB)]. The future of quinolones is uncertain, however, meanwhile they continue to be used in an irrational way, increasing resistance to quinolones should remain as an area of primary priority for research.

  7. Mechanism of quinolone action and resistance.

    Science.gov (United States)

    Aldred, Katie J; Kerns, Robert J; Osheroff, Neil

    2014-03-18

    Quinolones are one of the most commonly prescribed classes of antibacterials in the world and are used to treat a variety of bacterial infections in humans. Because of the wide use (and overuse) of these drugs, the number of quinolone-resistant bacterial strains has been growing steadily since the 1990s. As is the case with other antibacterial agents, the rise in quinolone resistance threatens the clinical utility of this important drug class. Quinolones act by converting their targets, gyrase and topoisomerase IV, into toxic enzymes that fragment the bacterial chromosome. This review describes the development of the quinolones as antibacterials, the structure and function of gyrase and topoisomerase IV, and the mechanistic basis for quinolone action against their enzyme targets. It will then discuss the following three mechanisms that decrease the sensitivity of bacterial cells to quinolones. Target-mediated resistance is the most common and clinically significant form of resistance. It is caused by specific mutations in gyrase and topoisomerase IV that weaken interactions between quinolones and these enzymes. Plasmid-mediated resistance results from extrachromosomal elements that encode proteins that disrupt quinolone-enzyme interactions, alter drug metabolism, or increase quinolone efflux. Chromosome-mediated resistance results from the underexpression of porins or the overexpression of cellular efflux pumps, both of which decrease cellular concentrations of quinolones. Finally, this review will discuss recent advancements in our understanding of how quinolones interact with gyrase and topoisomerase IV and how mutations in these enzymes cause resistance. These last findings suggest approaches to designing new drugs that display improved activity against resistant strains.

  8. 枸橼酸杆菌中质粒介导喹诺酮耐药基因的检测%Study of plasmid-mediated quinolone resistance determinants in Citrobacter freundii

    Institute of Scientific and Technical Information of China (English)

    邵宜波; 李旭; 胡立芬; 谢琴秀

    2013-01-01

    目的 了解枸橼酸杆菌中质粒介导喹诺酮耐药(PMQR)基因的分布,以期发现新型PMQR基因.测定临床分离的PMQR基因阳性枸橼酸杆菌对临床常用抗菌药物的敏感性.方法 收集安徽医科大学第一附属医院检验科2009年临床分离的枸橼酸杆菌,PCR扩增qnr、aac(6′)-Ib-cr和qepA基因,产物纯化测序,测序结果在GenBank上比对并行转移接合实验.对收集的PMQR基因阳性枸橼酸杆菌及其接合子,采用琼脂对倍稀释法进行临床常用抗菌药物的药物敏感试验.结果 收集的枸橼酸杆菌共31株,8株菌株扩增出qnr,qnr基因阳性率为25.8%;其中6株扩增出qnrB.4株qnr阳性菌株的qnr基因转移接合成功.在qnr阳性的枸橼酸杆菌中,测序发现1种PMQR基因新亚型,命名为qnrB24.所有qnr阳性临床菌株对喹诺酮类药物的耐药率为87.5%,对头孢噻肟、阿米卡星、头孢他啶、头孢吡肟和庆大霉素的耐药率分别为75.0%、7.5%、62.5%、37.5%和87.5%,所有qnr阳性菌株对亚胺培南耐药表型为敏感.喹诺酮类药物对qnr阳性的接合子最低抑菌浓度升高10~23倍,敏感性下降.结论 安徽地区枸橼酸杆菌中qnr基因型的检出率较高,以qnrB基因型为主,qnr阳性枸橼酸杆菌对常用抗菌药物耐药性较高.%Objectives This study was conducted to detect and analyze the presence of plasmidmediated quinolone resistance (PMQR) determinants [qnr,aac-(6′)-Ib-cr and qepA] among clinical isolates of Citrobacter freundii strains isolated from patients in Anhui,China,and to understand the susceptibility of PMQR positive strains to commonly used antimicrobial agents.Methods During the year 2009,31 Citrobacter strains were collected from the First Affiliated Hospital of Anhui Medical University.Polymerase chain reaction (PCR) was used to detect PMQR genes.Amplicons were purified,sequenced and compared with data from the GenBank.Conjugation experiments were conducted to

  9. 深圳市菌痢流行分子特征与对质粒介导的喹诺酮耐药机制%The molecular characteristics of bacillary dysentery epidemic and the antibiotic resistance mechanisms of plasmid mediated quinolones in Shenzhen

    Institute of Scientific and Technical Information of China (English)

    蔡长争; 舒少为; 陈爱平; 黄国清; 周美容

    2016-01-01

    Objective To analyze the molecular characteristics of bacillary dysentery epidemic and the antibiotic resistance mechanisms of plasmid mediated quinolones in Shenzhen.Methods Clinical specimens were collected in 18 hospitals in Shenzhen form January 2010 to Febuary 2014 and isolation cultivation and serotype identiifcation were applied. The plasmid mediated main type of quinolones genes were detected by PCR. Minimal inhibitory concentration (MIC) was tested by Agar dilution method. Transcojugants genotype and drug resistance were tested by joint transfer experiment.Results Serological distribution: during all 126 strains ofShigella, there were 108 (87.51%) strains ofShigellalfexneri and 16 (12.70%) strains ofShigella sonnei. The superiority serotype of shigella flexneri was serumⅣ-C, with 42 strains counted for 38.89%. Commonly used antimicrobial susceptibility situation analysis: the sensitivity ofShigella lfexneri to NAl, FEP and GM were signiifcantly lower than that ofShigella sonnei, while the sensitivity ofShigella lfexneri to LEV, GIP, NOR, CAZ and AMC were signiifcantly higher than that ofShigella sonnei (P all < 0.05). Ampliifcation results and sequence analysis: 3 (2.38%) cases with qnr genes, 4 cases with aac6’ genes, and 1 case with qepA genes were checked out in 126 strainsShigella. Minimum inhibitory concentration: compared with receptor bacteria, the MIC of transconjugants on NAL, GIP, LEV, NOR, GM were improved by 2-32 times. Conclusions The main types ofShigella infection in Shenzhen areShigella lfexneri andShigellasonnei. The superiority serotype of shigella lfexneri isⅣ-C. Target gene mutation is the main cause of quinolones resistance. The quinolones resistance of different types of shigella varies signiifcantly.%目的:分析深圳市菌痢流行分子特征及对质粒介导的喹诺酮耐药机制。方法对2010年1月至2014年2月深圳市18家医院收集的临床标本进行分离培养与血清型鉴定,

  10. Prevalence and characteristics of quinolone resistance in Escherichia coli in veal calves

    NARCIS (Netherlands)

    Hordijk, J.; Veldman, K.T.; Dierikx, C.M.; Essen-Zandbergen, van A.; Wagenaar, J.A.; Mevius, D.J.

    2012-01-01

    Quinolone resistance is studied and reported increasingly in isolates from humans, food-producing animals and companion animals. Resistance can be caused by chromosomal mutations in topoisomerase genes, plasmid-mediated resistance genes, and active transport through efflux pumps. Cross sectional dat

  11. Prevalence and characteristics of quinolone resistance in Escherichia coli in veal calves

    NARCIS (Netherlands)

    Hordijk, J.; Veldman, K.T.; Dierikx, C.M.; Essen-Zandbergen, van A.; Wagenaar, J.A.; Mevius, D.J.

    2012-01-01

    Quinolone resistance is studied and reported increasingly in isolates from humans, food-producing animals and companion animals. Resistance can be caused by chromosomal mutations in topoisomerase genes, plasmid-mediated resistance genes, and active transport through efflux pumps. Cross sectional dat

  12. Prevalence and characteristics of quinolone resistance in Escherichia coli in veal calves.

    Science.gov (United States)

    Hordijk, Joost; Veldman, Kees; Dierikx, Cindy; van Essen-Zandbergen, Alieda; Wagenaar, Jaap A; Mevius, Dik

    2012-04-23

    Quinolone resistance is studied and reported increasingly in isolates from humans, food-producing animals and companion animals. Resistance can be caused by chromosomal mutations in topoisomerase genes, plasmid-mediated resistance genes, and active transport through efflux pumps. Cross sectional data on quinolone resistance mechanisms in non-pathogenic bacteria from healthy veal calves is limited. The purpose of this study was to determine the prevalence and characteristics of quinolone resistance mechanisms in Escherichia coli isolates from veal calves, after more than 20 years of quinolone usage in veal calves. MIC values were determined for all isolates collected as part of a national surveillance program on antimicrobial resistance in commensal bacteria in food-producing animals in The Netherlands. From the strains collected from veal calves in 2007 (n=175) all isolates with ciprofloxacin MIC ≥ 0.125 mg/L (n=25) were selected for this study, and screened for the presence of known quinolone resistance determinants. In this selection only chromosomal mutations in the topoisomerase type II and IV genes were detected. The number of mutations found per isolate correlated with an increasing ciprofloxacin MIC. No plasmid-mediated quinolone resistance genes were found. The contribution of efflux pumps varied from no contribution to a 16-fold increase in susceptibility. No correlation was found with the presence of resistance genes of other antimicrobial classes, even though all quinolone non-wild type isolates were resistant to 3 or more classes of antibiotics other than quinolones. Over twenty years of quinolone usage in veal calves in The Netherlands did not result in a widespread occurrence of plasmid-mediated quinolone resistance, limiting the transmission of quinolone resistance to clonal distribution.

  13. Analysis of plasmid-mediated multidrug resistance in Escherichia coli and Klebsiella oxytoca isolates from clinical specimens in Japan.

    Science.gov (United States)

    Ode, Takashi; Saito, Ryoichi; Kumita, Wakako; Sato, Kenya; Okugawa, Shu; Moriya, Kyoji; Koike, Kazuhiko; Okamura, Noboru

    2009-10-01

    This study investigated the relationship of plasmid-mediated quinolone resistance (PMQR) and aminoglycoside resistance among oxyimino-cephalosporin-resistant Escherichia coli (n=46) and Klebsiella oxytoca (n=28) clinical isolates in Japan. Seventy-three isolates appeared to produce an extended-spectrum beta-lactamase (ESBL) and one K. oxytoca isolate produced IMP-1 metallo-beta-lactamase (MBL). Polymerase chain reaction (PCR) and sequencing confirmed that eight CTX-M-9/SHV-12-producing isolates, one IMP-1-producing K. oxytoca isolate, and six ESBL-positive E. coli isolates respectively possessed PMQR genes qnrA1, qnrB6, and aac(6')-Ib-cr. All qnr-positive isolates also carried either aac(6')-Ib or aac(6')-IIc aminoglycoside acetyltransferase genes. Resistance determinants to beta-lactams, quinolones and aminoglycosides were co-transferred with a plasmid of ca. 140 kb. The qnrA1 gene was located downstream of insertion sequence ISCR1 in complex class 1 integrons. A novel qnrA1-carrying class 1 integron with the cassette arrangement aac(6')-IIc-aadA2 as well as a unique class 1 integron with bla(IMP-1)-aac(6')-IIc cassettes on the plasmid carrying qnrB6 were found in K. oxytoca isolates. We describe the identification of qnrB6 and aac(6')-Ib-cr and the close association of qnr with aac(6')-Ib and aac(6')-IIc for the first time in clinical isolates producing ESBL or MBL in Japan.

  14. Prevalence and characterisation of quinolone resistance mechanisms in Salmonella spp.

    Science.gov (United States)

    Wasyl, Dariusz; Hoszowski, Andrzej; Zając, Magdalena

    2014-07-16

    The study was focused on characterisation of quinolone resistance mechanisms in Salmonella isolated from animals, food, and feed between 2008 and 2011. Testing of Minimal Inhibitory Concentrations revealed 6.4% of 2680 isolates conferring ciprofloxacin resistance. Simultaneously 37.7% and 40.8% were accounted for, respectively, nalidixic acid and ciprofloxacin Non Wild-Type populations. Amplification and sequencing of quinolone resistance determining region of topoisomerases genes in 44 isolates identified multiple amino-acid substitutions in gyrA at positions Ser83 (N=22; → Leu, → Phe, → Tyr), Asp87 (N=22; → Asn, → Gly, → Tyr) and parC (Thr57Ser, N=23; Ala141Ser, N=1). No relevant mutations were identified in gyrB and parE. Twelve patterns combining one or two substitutions were related to neither serovar nor ciprofloxacin MIC. In 92 isolates suspected for plasmid mediated quinolone resistance two qnr alleles were found: qnrS1 (or qnrS3; N=50) and qnrB19 (or qnrB10; N=24). Additionally, two isolates with chromosomally encoded mechanisms carried qnrS1 and qnrS2. All tested isolates were negative for qnrA, qnrC, qnrD, qepA, aac(6')-Ib-cr. Both chromosomal and plasmid mediated quinolone resistance determinants were found in several Salmonella serovars and Pulsed Field Gel Electrophoresis was used to assess phylogenetic similarity of selected isolates (N=82). Salmonella Newport was found to accumulate quinolone resistance determinants and the serovar was spreading clonally with either variable gyrA mutations, qnrS1/S3, or qnrB10/B19. Alternatively, various determinants are dispersed among related S. Enteritidis isolates. Antimicrobial selection pressure, multiple resistance determinants and scenarios for their acquisition and spread make extremely difficult to combat quinolone resistance.

  15. Prevalence of plasmid-mediated multidrug resistance determinants in fluoroquinolone-resistant bacteria isolated from sewage and surface water.

    Science.gov (United States)

    Osińska, Adriana; Harnisz, Monika; Korzeniewska, Ewa

    2016-06-01

    Fluoroquinolones (FQs) are fully synthetic broad-spectrum antibacterial agents that are becoming increasingly popular in the treatment of clinical and veterinary infections. Being excreted during treatment, mostly as active compounds, their biological action is not limited to the therapeutic site, but it is moved further as resistance selection pressure into the environment. Water environment is an ideal medium for the aggregation and dissemination of antibiotics, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs), which can pose a serious threat to human health. Because of this, the aim of this study was to determine the number of fluoroquinolone-resistant bacteria (FQRB) and their share in total heterotrophic plate counts (HPC) in treated wastewater (TWW), and upstream and downstream river water (URW, DRW) samples where TWW is discharged. The spread of plasmid-mediated quinolone resistance (PMQR) determinants and the presence/absence of resistance genes to other most popular antibiotic groups (against tetracyclines and beta-lactams) in selected 116 multiresistant isolates were investigated. The share of FQRB in total HPC in all samples was rather small and ranged from 0.7 % in URW samples to 7.5 % in TWW. Bacteria from Escherichia (25.0 %), Acinetobacter (25.0 %), and Aeromonas (6.9 %) genera were predominant in the FQRB group. Fluoroquinolone resistance was mostly caused by the presence of the gene aac(6')-1b-cr (91.4 %). More rarely reported was the occurrence of qnrS, qnrD, as well as oqxA, but qnrA, qnrB, qepA, and oqxB were extremely rarely or never noted in FQRB. The most prevalent bacterial genes connected with beta-lactams' resistance in FQRB were bla TEM, bla OXA, and bla CTX-M. The bla SHV was less common in the community of FQRB. The occurrence of bla genes was reported in almost 29.3 % of FQRB. The most abundant tet genes in FQRB were tet(A), tet(L), tet(K), and tet(S). The prevalence of tet genes was observed in 41.4

  16. Transfer of plasmid-mediated ampicillin resistance from Haemophilus to Neisseria gonorrhoeae requires an intervening organism.

    Science.gov (United States)

    McNicol, P J; Albritton, W L; Ronald, A R

    1986-01-01

    Haemophilus species have been implicated as the source of plasmid-mediated ampicillin resistance in Neisseria gonorrhoeae. Previous attempts to transfer conjugally the resistance plasmids from Haemophilus species to N. gonorrhoeae have met with limited success. Using both biparental and triparental mating systems, it was found that transfer will occur if the commensal Neisseria species, Neisseria cinerea, is used as a transfer intermediate. This organism stably maintains resistance plasmids of Haemophilus and facilitates transfer of these plasmids to N. gonorrhoeae, in a triparental mating system, at a transfer frequency of 10(-8). Both Haemophilus ducreyi and N. gonorrhoeae carry mobilizing plasmids capable of mediating conjugal transfer of the same resistance plasmids. However, restriction endonuclease mapping and DNA hybridization studies indicate that the mobilizing plasmids are distinctly different molecules. Limited homology is present within the transfer region of these plasmids.

  17. Plasmid-Mediated Colistin Resistance Gene mcr-1 in an Escherichia coli ST10 Bloodstream Isolate in the Sultanate of Oman.

    Science.gov (United States)

    Mohsin, Jalila; Pál, Tibor; Petersen, Jorgen Eskild; Darwish, Dania; Ghazawi, Akela; Ashraf, Tanveer; Sonnevend, Agnes

    2017-08-11

    To identify plasmid-mediated colistin resistance in clinical Enterobacteriaceae isolates in Oman, where this resistance mechanism has not been encountered yet. Twenty-two colistin-resistant Enterobacteriaceae clinical isolates collected between July 2014 and June 2016 in a tertiary care hospital in Muscat were screened by PCR for the mcr-1 and mcr-2 genes. The strain identified as mcr-1 positive was genotyped and its antibiotic susceptibility was established. The mcr-1 containing plasmid was mobilized into Escherichia coli K-12 and its sequence was determined. A single E. coli isolate (OM97) carrying mcr-1 gene was identified, while no strains carrying the mcr-2 gene was found. E. coli OM97 was isolated in June 2016 from blood culture of a male patient with multiple comorbidities. It belonged to ST10. Beyond colistin, it was resistant to amoxicillin-clavulanic acid, piperacillin-tazobactam, amikacin, ciprofloxacin, tetracycline, and cotrimoxazole. The mcr-1 gene was located on a conjugative IncI2-type plasmid of 63722 bp size, which did not harbor any further resistance genes. The genetic surrounding of the mcr-1 gene lacked the ISApl1 element. Although colistin resistance caused by the mcr-1 gene is not common in our collection of clinical isolates, the occurrence of the plasmid-mediated colistin resistance in an E. coli ST10 strain is of concern as this clonal group was already shown to spread ESBL genes and quinolone resistance worldwide. It is especially worrisome that as the mcr-1 gene occurred in a non-ESBL, carbapenem-susceptible E. coli strain, current susceptibility testing algorithms may not detect its presence.

  18. Plasmid-Mediated OqxAB Is an Important Mechanism for Nitrofurantoin Resistance in Escherichia coli.

    Science.gov (United States)

    Ho, Pak-Leung; Ng, Ka-Ying; Lo, Wai-U; Law, Pierra Y; Lai, Eileen Ling-Yi; Wang, Ya; Chow, Kin-Hung

    2015-11-09

    Increasing consumption of nitrofurantoin (NIT) for treatment of acute uncomplicated urinary tract infections (UTI) highlights the need to monitor emerging NIT resistance mechanisms. This study investigated the molecular epidemiology of the multidrug-resistant efflux gene oqxAB and its contribution to nitrofurantoin resistance by using Escherichia coli isolates originating from patients with UTI (n = 205; collected in 2004 to 2013) and food-producing animals (n = 136; collected in 2012 to 2013) in Hong Kong. The oqxAB gene was highly prevalent among NIT-intermediate (11.5% to 45.5%) and -resistant (39.2% to 65.5%) isolates but rare (0% to 1.7%) among NIT-susceptible (NIT-S) isolates. In our isolates, the oqxAB gene was associated with IS26 and was carried by plasmids of diverse replicon types. Multilocus sequence typing revealed that the clones of oqxAB-positive E. coli were diverse. The combination of oqxAB and nfsA mutations was found to be sufficient for high-level NIT resistance. Curing of oqxAB-carrying plasmids from 20 NIT-intermediate/resistant UTI isolates markedly reduced the geometric mean MIC of NIT from 168.9 μg/ml to 34.3 μg/ml. In the plasmid-cured variants, 20% (1/5) of isolates with nfsA mutations were NIT-S, while 80% (12/15) of isolates without nfsA mutations were NIT-S (P = 0.015). The presence of plasmid-based oqxAB increased the mutation prevention concentration of NIT from 128 μg/ml to 256 μg/ml and facilitated the development of clinically important levels of nitrofurantoin resistance. In conclusion, plasmid-mediated oqxAB is an important nitrofurantoin resistance mechanism. There is a great need to monitor the dissemination of this transferable multidrug-resistant efflux pump.

  19. Horizontal Transfer of Plasmid-Mediated Cephalosporin Resistance Genes in the Intestine of Houseflies (Musca domestica).

    Science.gov (United States)

    Fukuda, Akira; Usui, Masaru; Okubo, Torahiko; Tamura, Yutaka

    2016-06-01

    Houseflies are a mechanical vector for various types of bacteria, including antimicrobial-resistant bacteria (ARB). If the intestine of houseflies is a suitable site for the transfer of antimicrobial resistance genes (ARGs), houseflies could also serve as a biological vector for ARB. To clarify whether cephalosporin resistance genes are transferred efficiently in the housefly intestine, we compared with conjugation experiments in vivo (in the intestine) and in vitro by using Escherichia coli with eight combinations of four donor and two recipient strains harboring plasmid-mediated cephalosporin resistance genes and chromosomal-encoded rifampicin resistance genes, respectively. In the in vivo conjugation experiment, houseflies ingested donor strains for 6 hr and then recipient strains for 3 hr, and 24 hr later, the houseflies were surface sterilized and analyzed. In vitro conjugation experiments were conducted using the broth-mating method. In 3/8 combinations, the in vitro transfer frequency (Transconjugants/Donor) was ≥1.3 × 10(-4); the in vivo transfer rates of cephalosporin resistance genes ranged from 2.0 × 10(-4) to 5.7 × 10(-5). Moreover, cephalosporin resistance genes were transferred to other species of enteric bacteria of houseflies such as Achromobacter sp. and Pseudomonas fluorescens. These results suggest that houseflies are not only a mechanical vector for ARB but also a biological vector for the occurrence of new ARB through the horizontal transfer of ARGs in their intestine.

  20. Mechanisms of drug resistance: quinolone resistance.

    Science.gov (United States)

    Hooper, David C; Jacoby, George A

    2015-09-01

    Quinolone antimicrobials are synthetic and widely used in clinical medicine. Resistance emerged with clinical use and became common in some bacterial pathogens. Mechanisms of resistance include two categories of mutation and acquisition of resistance-conferring genes. Resistance mutations in one or both of the two drug target enzymes, DNA gyrase and DNA topoisomerase IV, are commonly in a localized domain of the GyrA and ParE subunits of the respective enzymes and reduce drug binding to the enzyme-DNA complex. Other resistance mutations occur in regulatory genes that control the expression of native efflux pumps localized in the bacterial membrane(s). These pumps have broad substrate profiles that include quinolones as well as other antimicrobials, disinfectants, and dyes. Mutations of both types can accumulate with selection pressure and produce highly resistant strains. Resistance genes acquired on plasmids can confer low-level resistance that promotes the selection of mutational high-level resistance. Plasmid-encoded resistance is due to Qnr proteins that protect the target enzymes from quinolone action, one mutant aminoglycoside-modifying enzyme that also modifies certain quinolones, and mobile efflux pumps. Plasmids with these mechanisms often encode additional antimicrobial resistances and can transfer multidrug resistance that includes quinolones. Thus, the bacterial quinolone resistance armamentarium is large.

  1. Emergence and Spread of A Plasmid-Mediated Polymyxin Resistance Mechanism, MCR-1: Are Bacteria Winning?

    Directory of Open Access Journals (Sweden)

    Chao Yang

    2015-12-01

    Full Text Available The report of the emergence of mcr-1, the first plasmid-mediated polymyxin resistance mechanism, in Enterobacteriaceae in November 2015 challenged our last psychological line of defense. However, we still trusted that this resistance factor had not spread globally. One month later, in December 2015, the detection of mcr-1 in an Escherichia coliisolate from a septicemic patient in Denmark and in five E. coli isolates from imported chicken meat really defeated us. The worst news was that one of the chicken meat isolates belonged to ST131, a spreading epidemic sequence type. In China, 15%-21% of E. coli strains isolated from raw meat and animals carried mcr-1, and about 1% of patient isolates carried this gene, indicating that E. coli carrying this plasmid is not a rare phenomenon. This gene is transferable by conjugation and can be maintained in Klebsiella pneumonia and Pseudomonas aeruginosa, suggesting the risk of transfer between different bacterial genera. The good news is that the strains carrying mcr-1 do not contain genes for pan-resistance profiles, although some Danish strains contain 15 different resistance genes, including genes for extended-spectrum beta-lactam antibiotics, and gene mutations leading to high-level fluoroquinolone resistance. If the mcr-1-bearing strains acquire multidrug resistance, extensive drug resistance, or pandrug resistance, no antibiotic drugs will be available with which clinicians can treat infected patients. Therefore, the use of antibiotics in both hospitals and the animal breeding industry must be strictly regulated. The origin of mcr-1 may be associated with the wide use of colistin in agriculture. There is no evidence that the Danish mcr-1 gene spread from China. Therefore, it is likely that mcr-1 genes originated in multiple sites simultaneously under the pressure of colistin use, because India and Denmark are the world’ s greatest users of this antibiotic. More surveys must be conducted in different

  2. Mechanisms of quinolone resistance and implications for human and animal health

    Directory of Open Access Journals (Sweden)

    Velhner Maja

    2010-01-01

    Full Text Available Quinolone antibiotics have been widely used in human and veterinary medicine. This has caused the development of resistance and difficulties in the treatment of complicated bacterial infections in humans. The resistance to quinolones develops due to chromosome mutations and it can also be transferred by plasmids. The target enzyme for quinolones in Gram-negative bacteria is Gyrasa A, while the target enzyme in Grampositive bacteria is mostly topoisomerase IV. Gyrase A consists of two subunits encoded by genes gyrA and gyrB. The function of the enzyme is to introduce negative super coiling in DNA and therefore is essential for the replication of bacteria. Quinolone resistance develops if point mutations at 83 and/or 87 codon are introduced on gyrA. Establishing a minimal inhibitory concentration (MIC to this group of antimicrobials will reveal possible mutations. Recently it was discovered that quinolone resistance is transmittable by plasmid termed PMQR (plasmid mediated quinolone resistance. The target gene marked qnr encodes a pentapeptide repeat family protein. Pentapeptide repeats form sheets, involved in protein-protein interactions. Qnr protein binds to GyrA protecting the enzyme from the inhibitory effect of ciprofloxacin. The distribution of qnr related resistance is higher in humans than in animals. In poultry, however, this type of resistance is present more than in other animals. Plasmid mediated resistance contributes to the faster spread of quinolone resistance. Proper food handling will significantly contribute to decreasing the risk from infection to which people are exposed. In medical and veterinary laboratories antimicrobial resistance monitoring in clinical and environmental isolates is advised. Since correlation between antibiotics application and antimicrobial resistance is often suggested, antimicrobial use must be under strict control of the authorities both in human and in veterinary medicine. .

  3. Quinolone-resistant Escherichia coli in Poultry Farming.

    Science.gov (United States)

    Hricová, Kristýna; Röderová, Magdaléna; Pudová, Vendula; Hanulík, Vojtěch; Halová, Dana; Julínková, Pavla; Dolejská, Monika; Papoušek, Ivo; Bardoň, Jan

    2017-06-01

    Increasing bacterial resistance to quinolone antibiotics is apparent in both humans and animals. For humans, a potential source of resistant bacteria may be animals or their products entering the human food chain, for example poultry. Between July 2013 and September 2014, samples were collected and analyzed in the Moravian regions of the Czech Republic to isolate the bacterium Escherichia coli. As a result, 212 E. coli isolates were obtained comprising 126 environmental isolates from poultry houses and 86 isolates from cloacal swabs from market-weight turkeys. Subsequently, the E. coli isolates were tested for susceptibility to selected antibiotics. Resistance of the poultry isolates to quinolones ranged from 53% to 73%. Additionally, the presence of plasmid-mediated resistance genes was studied. The genes were confirmed in 58% of the tested strains. The data on resistance of isolates from poultry were compared with results of resistance tests in human isolates obtained in the same regions. The high levels of resistance determined by both phenotyping and genotyping methods and reported in the present study confirm the fact that the use of fluoroquinolones in poultry should be closely monitored. Copyright© by the National Institute of Public Health, Prague 2017.

  4. Quinolone resistance: much more than predicted

    Directory of Open Access Journals (Sweden)

    Alvaro eHernandez

    2011-02-01

    Full Text Available Since quinolones are synthetic antibiotics, it was predicted that mutations in target genes would be the only mechanism through which resistance could be acquired, because there will not be quinolone resistance genes in nature. Contrary to this prediction, a variety of elements ranging from efflux pumps, target-protecting proteins and even quinolone-modifying enzymes have been shown to contribute to quinolone resistance. The finding of some of these elements in plasmids indicates that quinolone resistance can be transferable. As a result, there has been a developing interest on the reservoirs for quinolone resistance genes and on the potential risks associated with the use of these antibiotics in non-clinical environments. As a matter of fact, plasmid-encoded, quinolone-resistance qnr genes originated in the chromosome of aquatic bacteria, thus the use of quinolones in fish farming might constitute a risk for the emergence of resistance. Failure to predict the development of quinolone resistance reinforces the need of taking into consideration the wide plasticity of biological systems for future predictions. This plasticity allows pathogens to deal with toxic compounds, including those with a synthetic origin as quinolones.

  5. Prevalence and characteristics of extended-spectrum β-lactamase and plasmid-mediated fluoroquinolone resistance genes in Escherichia coli isolated from chickens in Anhui province, China.

    Directory of Open Access Journals (Sweden)

    Lin Li

    Full Text Available The aim of this study was to characterize the prevalence of extended-spectrum β-lactamase (ESBL genes and plasmid-mediated fluoroquinolone resistance (PMQR determinants in 202 Escherichia coli isolates from chickens in Anhui Province, China, and to determine whether ESBL and PMQR genes co-localized in the isolates. Antimicrobial susceptibility for 12 antimicrobials was determined by broth microdilution. Polymerase chain reactions (PCRs, DNA sequencing, and pulsed field gel electrophoresis (PFGE were employed to characterize the molecular basis for β-lactam and fluoroquinolone resistance. High rates of antimicrobial resistance were observed, 147 out of the 202 (72.8% isolates were resistant to at least 6 antimicrobial agents and 28 (13.9% of the isolates were resistant to at least 10 antimicrobials. The prevalence of blaCTX-M, blaTEM-1 and blaTEM-206 genes was 19.8%, 24.3% and 11.9%, respectively. Seventy-five out of the 202 (37.1% isolates possessed a plasmid-mediated quinolone resistance determinant in the form of qnrS (n = 21; this determinant occurred occasionally in combination with aac(6'-1b-cr (n = 65. Coexistence of ESBL and/or PMQR genes was identified in 31 of the isolates. Two E. coli isolates carried blaTEM-1, blaCTX-M and qnrS, while two others carried blaCTX-M, qnrS and aac(6'-1b-cr. In addition, blaTEM-1, qnrS and aac(6'-1b-cr were co-located in two other E. coli isolates. PFGE analysis showed that these isolates were not clonally related and were genetically diverse. To the best of our knowledge, this study is the first to describe detection of TEM-206-producing E. coli in farmed chickens, and the presence of blaTEM-206, qnrS and aac(6'-1b-cr in one of the isolates.

  6. [The effectiveness of empirical antibiotic therapy of pyelonephritis in patients with type 2 diabetes and without depending on the availability of plasmid-mediated resistance genes].

    Science.gov (United States)

    Chub, O I; Bilchenko, A V

    2015-02-01

    Multi-drug resistance has been increasing in the treatment of urinary tract infections, especially complicated. The prevalence of plasmid-mediated resistance genes among urinary pathogens has nether been studied in Ukraine. So, the aim of our study was to identify the plasmid-mediated resistance genes and to determine their impact on the efficacy of the treatment. A total of 105 adult patients with chronic pyelonephritis were included in the study. Among them, 32 patients were diagnosed with type 2 diabetes mellitus. The diagnosis of pyelonephritis was verified according to the criteria EAU, 2013. Plasmid-mediated resistance genes were determined by polymerase chain reaction (PCR). The prevalence of plasmid-mediated resistance mechanisms among patients with pyelonephritis were 44,4%. ESBLs was the most common isolated genes. Favorable clinical response was seen in 11/31 (35,5%) infected with ESBL-producing organisms compared with 59/74 (79,7%) patients with non-ESBL-producing organisms (ppyelonephritis due to presence of plasmid-mediated resistance genes. Therefore, prоpеr mаnagеment fоr prescriptiоn of аntibiоtics and also idеntificаtiоn of ESBL-prоducing bаcteria in cоmmunitiеs arе impоrtant fоr prevеntion.

  7. Introduction of quinolone resistant Escherichia coli to Swedish broiler population by imported breeding animals.

    Science.gov (United States)

    Börjesson, Stefan; Guillard, Thomas; Landén, Annica; Bengtsson, Björn; Nilsson, Oskar

    2016-10-15

    During recent years a rapid increase of quinolone resistant Escherichia coli have been noted in the Swedish broiler population, despite the lack of a known selective pressure. The current study wanted to investigate if imported breeding birds could be a source for the quinolone resistant E. coli. The occurrence of quinolone resistant E. coli was investigated, using selective cultivation with nalidixic acid, in grand-parent birds on arrival to Sweden and their progeny. In addition, sampling in hatcheries and empty cleaned poultry houses was performed. Clonality of isolates was investigated using a 10-loci multiple-locus variable number tandem repeat analysis (MLVA). To identify the genetic basis for the resistance isolates were also analysed for occurrence of plasmid-mediated quinolone resistance (PMQR) determinants and characterization of chromosomal mutations. E. coli resistant to nalidixic acid occurred in grandparent birds imported to Sweden for breeding purposes. Four predominant MLVA types were identified in isolates from grandparent birds, parent birds and broilers. However, resistant E. coli with identical MLVA patterns were also present in hatcheries and poultry houses suggesting that the environment plays a role in the occurrence. Nalidixic acid resistance was due to a mutation in the gyrA gene and no PMQR could be identified. The occurrence of identical clones in all levels of the production pyramid points to that quinolone resistant E. coli can be introduced through imported breeding birds and spread by vertical transmission to all levels of the broiler production pyramid.

  8. First environmental sample containing plasmid-mediated colistin-resistant ESBL-producing Escherichia coli detected in Norway.

    Science.gov (United States)

    Jørgensen, Silje Bakken; Søraas, Arne; Arnesen, Lotte Stenfors; Leegaard, Truls; Sundsfjord, Arnfinn; Jenum, Pål A

    2017-09-01

    We hereby report the detection of the plasmid borne mcr-1 gene conferring colistin resistance in an extended-spectrum β-lactamase (ESBL) producing Escherichia coli ST10 strain retrieved from seawater at a public beach in Norway. The sample was collected in September 2010 and was investigated by whole-genome sequencing in 2016. This report illustrates that E. coli strains carrying plasmid-mediated colistin resistance genes have also reached areas where this drug is hardly used at all. Surveillance of colistin resistance in environmental, veterinary, and human strains is warranted also in countries where colistin resistance is rare in clinical settings. © 2017 APMIS. Published by John Wiley & Sons Ltd.

  9. IncA/C plasmid-mediated spread of CMY-2 in multidrug-resistant Escherichia coli from food animals in China.

    Science.gov (United States)

    Guo, Yu-Fang; Zhang, Wen-Hui; Ren, Si-Qi; Yang, Lin; Lü, Dian-Hong; Zeng, Zhen-Ling; Liu, Ya-Hong; Jiang, Hong-Xia

    2014-01-01

    To obtain a broad molecular epidemiological characterization of plasmid-mediated AmpC β-lactamase CMY-2 in Escherichia coli isolates from food animals in China. A total of 1083 E. coli isolates from feces, viscera, blood, drinking water, and sub-surface soil were examined for the presence of CMY-2 β-lactamases. CMY-2-producing isolates were characterized as follows: the blaCMY-2 genotype was determined using PCR and sequencing, characterization of the blaCMY-2 genetic environment, plasmid sizing using S1 nuclease pulsed-field gel electrophoresis (PFGE), PCR-based replicon typing, phylogenetic grouping, XbaI-PFGE, and multi-locus sequence typing (MLST). All 31 CMY-2 producers were only detected in feces, and presented with multidrug resistant phenotypes. All CMY-2 strains also co-harbored genes conferring resistance to other antimicrobials, including extended spectrum β-lactamases genes (blaCTX-M-14 or blaCTX-M-55), plasmid-mediated quinolone resistance determinants (qnr, oqxA, and aac-(6')-Ib-cr), floR and rmtB. The co-transferring of blaCMY-2 with qnrS1 and floR (alone and together) was mainly driven by the Inc A/C type plasmid, with sizes of 160 or 200 kb. Gene cassette arrays inserted in the class 1 or class 2 integron were amplified among 12 CMY-2 producers. CMY-2 producers belonged to avirulent groups B1 (n = 12) and A (n = 11), and virulent group D (n = 8). There was a good correlation between phylogenetic groups and sequence types (ST). Twenty-four STs were identified, of which the ST complexes (STC) 101/B1 (n = 6), STC10/A (n = 5), and STC155/B1 (n = 3) were dominant. CMY-2 is the dominant AmpC β-lactamase in food animals and is associated with a transferable replicon IncA/C plasmid in the STC101, STC10, and STC155 strains.

  10. IncA/C plasmid-mediated spread of CMY-2 in multidrug-resistant Escherichia coli from food animals in China.

    Directory of Open Access Journals (Sweden)

    Yu-Fang Guo

    Full Text Available OBJECTIVES: To obtain a broad molecular epidemiological characterization of plasmid-mediated AmpC β-lactamase CMY-2 in Escherichia coli isolates from food animals in China. METHODS: A total of 1083 E. coli isolates from feces, viscera, blood, drinking water, and sub-surface soil were examined for the presence of CMY-2 β-lactamases. CMY-2-producing isolates were characterized as follows: the blaCMY-2 genotype was determined using PCR and sequencing, characterization of the blaCMY-2 genetic environment, plasmid sizing using S1 nuclease pulsed-field gel electrophoresis (PFGE, PCR-based replicon typing, phylogenetic grouping, XbaI-PFGE, and multi-locus sequence typing (MLST. RESULTS: All 31 CMY-2 producers were only detected in feces, and presented with multidrug resistant phenotypes. All CMY-2 strains also co-harbored genes conferring resistance to other antimicrobials, including extended spectrum β-lactamases genes (blaCTX-M-14 or blaCTX-M-55, plasmid-mediated quinolone resistance determinants (qnr, oqxA, and aac-(6'-Ib-cr, floR and rmtB. The co-transferring of blaCMY-2 with qnrS1 and floR (alone and together was mainly driven by the Inc A/C type plasmid, with sizes of 160 or 200 kb. Gene cassette arrays inserted in the class 1 or class 2 integron were amplified among 12 CMY-2 producers. CMY-2 producers belonged to avirulent groups B1 (n = 12 and A (n = 11, and virulent group D (n = 8. There was a good correlation between phylogenetic groups and sequence types (ST. Twenty-four STs were identified, of which the ST complexes (STC 101/B1 (n = 6, STC10/A (n = 5, and STC155/B1 (n = 3 were dominant. CONCLUSIONS: CMY-2 is the dominant AmpC β-lactamase in food animals and is associated with a transferable replicon IncA/C plasmid in the STC101, STC10, and STC155 strains.

  11. Plasmid-related quinolone resistance determinants in epidemic Vibrio parahaemolyticus, uropathogenic Escherichia coli, and marine bacteria from an aquaculture area in Chile.

    Science.gov (United States)

    Aedo, Sandra; Ivanova, Larisa; Tomova, Alexandra; Cabello, Felipe C

    2014-08-01

    Marine bacteria from aquaculture areas with industrial use of quinolones have the potential to pass quinolone resistance genes to animal and human pathogens. The VPA0095 gene, related to the quinolone resistance determinant qnrA, from clinical isolates of epidemic Vibrio parahaemolyticus conferred reduced susceptibility to quinolone after cloning into Escherichia coli K-12 either when acting alone or synergistically with DNA gyrase mutations. In addition, a plasmid-mediated quinolone resistance gene from marine bacteria, aac(6')-Ib-cr, was identical to aac(6')-Ib-cr from urinary tract isolates of E. coli, suggesting a recent flow of this gene between these bacteria isolated from different environments. aac(6')-Ib-cr from E. coli also conferred reduced susceptibility to quinolone and kanamycin when cloned into E. coli K-12.

  12. Characterization of quinolone resistance in Salmonella spp. isolates from food products and human samples in Brazil

    Science.gov (United States)

    Pribul, Bruno Rocha; Festivo, Marcia Lima; de Souza, Miliane Moreira Soares; dos Prazeres Rodrigues, Dalia

    2016-01-01

    Non-typhoidal salmonellosis is an important zoonotic disease caused by Salmonella enterica. The aim of this study was to investigate the prevalence of plasmid-mediated quinolone resistance in Salmonella spp. and its association with fluoroquinolone susceptibility in Brazil. A total of 129 NTS isolates (samples from human origin, food from animal origin, environmental, and animal) grouped as from animal (n = 62) and human (n = 67) food were evaluated between 2009 and 2013. These isolates were investigated through serotyping, antimicrobial susceptibility testing, and the presence of plasmid-mediated quinolone resistance (PMQR) genes (qnr, aac(6′)-Ib) and associated integron genes (integrase, and conserved integron region). Resistance to quinolones and/or fluoroquinolones, from first to third generations, was observed. Fifteen isolates were positive for the presence of qnr genes (8 qnrS, 6 qnrB, and 1 qnrD) and twenty three of aac(6′)-Ib. The conserved integron region was detected in 67 isolates as variable regions, from ±600 to >1000 pb. The spread of NTS involving PMQR carriers is of serious concern and should be carefully monitored. PMID:26887245

  13. Characterization of quinolone resistance in Salmonella spp. isolates from food products and human samples in Brazil.

    Science.gov (United States)

    Pribul, Bruno Rocha; Festivo, Marcia Lima; de Souza, Miliane Moreira Soares; Rodrigues, Dalia dos Prazeres

    2016-01-01

    Non-typhoidal salmonellosis is an important zoonotic disease caused by Salmonella enterica. The aim of this study was to investigate the prevalence of plasmid-mediated quinolone resistance in Salmonella spp. and its association with fluoroquinolone susceptibility in Brazil. A total of 129 NTS isolates (samples from human origin, food from animal origin, environmental, and animal) grouped as from animal (n=62) and human (n=67) food were evaluated between 2009 and 2013. These isolates were investigated through serotyping, antimicrobial susceptibility testing, and the presence of plasmid-mediated quinolone resistance (PMQR) genes (qnr, aac(6')-Ib) and associated integron genes (integrase, and conserved integron region). Resistance to quinolones and/or fluoroquinolones, from first to third generations, was observed. Fifteen isolates were positive for the presence of qnr genes (8 qnrS, 6 qnrB, and 1 qnrD) and twenty three of aac(6')-Ib. The conserved integron region was detected in 67 isolates as variable regions, from ±600 to >1000pb. The spread of NTS involving PMQR carriers is of serious concern and should be carefully monitored.

  14. Detection of mcr-1 encoding plasmid-mediated colistin-resistant Escherichia coli isolates from human bloodstream infection and imported chicken meat, Denmark 2015

    DEFF Research Database (Denmark)

    Hasman, H.; Hammerum, A. M.; Hansen, F.

    2015-01-01

    The plasmid-mediated colistin resistance gene, mcr-1, was detected in an Escherichia coli isolate from a Danish patient with bloodstream infection and in five E. coli isolates from imported chicken meat. One isolate from chicken meat belonged to the epidemic spreading sequence type ST131. In addi...

  15. Molecular epidemiological survey on quinolone resistance genotype and phenotype of Escherichia coli in septicemic broilers in Hebei, China.

    Science.gov (United States)

    Xie, Rong; Huo, Shuying; Li, Yurong; Chen, Ligong; Zhang, Feiyan; Wu, Xianjun

    2014-02-01

    In this study, the quinolone-resistant determining region (QRDR) of gyrA of Escherichia coli and plasmid-mediated quinolone resistance (PMQR) genes, qnr(qnrA, qnrB, and qnrS), and aac(6 ')-Ib-cr were detected, sequenced, and analyzed. In addition, antimicrobial susceptibility tests (using the Kirby-Bauer disc diffusion method) were performed for all 111 E. coli isolates from septicemic broilers in Hebei, China. The results show that the resistance rates were as follows: ofloxacin 99.10%, ciprofloxacin 93.69%, levofloxacin 91.89%, norfloxacin 90.09%, and gatifloxacin 76.58%. Of the PMQR genes examined, aac(6 ')-Ib-cr (36.04%) was the most frequently identified gene in all isolates, followed by qnrS (8.11%), qnrB (0.90%), and qnrA (0%). Of the QRDR examined in the 40 phenotypic quinolone-resistant isolates, compared with the gyrA(+) gene of E. coli K-12, 4 amino acid exchanges were found, namely Ser-83→Asp, Asp-87→Asn, Asp-87→Tyr, and Asp-87→Ala, and all 40 isolates had 1 or 2 exchanges in QRDR. It was concluded that quinolone-resistance in E. coli remains a serious problem in Hebei, China. Therefore, there is considerable local surveillance of quinolone resistance. Plasmid-mediated quinolone resistance of the qnr type remains rare in Hebei, China, and mutation in QRDR may be the main problem.

  16. Plasmid Mediated Antibiotic and Heavy Metal Resistance in Bacillus Strains Isolated From Soils in Rize, Turkey

    Directory of Open Access Journals (Sweden)

    Elif SEVİM

    2015-09-01

    Full Text Available Fifteen Bacillus strains which were isolated from soil samples were examined for resistance to 17 different antibiotics (ampicillin, methicillin, erythromycin, norfloxacin, cephalotine, gentamycin, ciprofloxacin, streptomycin, tobramycin, chloramphenicol, trimethoprim-sulfamethoxazole, tetracycline, vancomycin, oxacilin, neomycin, kanamycin and, novabiocin and to 10 different heavy metals (copper, lead, cobalt, chrome, iron, mercury, zinc, nickel, manganese and, cadmium and for the presence of plasmid DNA. A total of eleven strains (67% were resistant to at least one antibiotic. The most common resistance was observed against methicillin and oxacillin. The most resistance strains were found as Bacillus sp. B3 and Bacillus sp. B11. High heavy metal resistance against copper, chromium, zinc, iron and nickel was detected, but mercury and cobalt resistance was not detected, except for 3 strains (B3, B11, and B12 which showed mercury resistance. It has been determined that seven Bacillus strains have plasmids. The isolated plasmids were transformed into the Bacillus subtilis W168 and it was shown that heavy metal and antibiotic resistance determinants were carried on these plasmids. These results showed that there was a correlation between plasmid content and resistance for both antibiotic and heavy metal resistance

  17. Transfer of plasmid-mediated resistance to tetracycline in pathogenic bacteria from fish and aquaculture environments.

    Science.gov (United States)

    Guglielmetti, Elena; Korhonen, Jenni M; Heikkinen, Jouni; Morelli, Lorenzo; von Wright, Atte

    2009-04-01

    The transferability of a large plasmid that harbors a tetracycline resistance gene tet(S), to fish and human pathogens was assessed using electrotransformation and conjugation. The plasmid, originally isolated from fish intestinal Lactococcus lactis ssp. lactis KYA-7, has potent antagonistic activity against the selected recipients (Lactococcus garvieae and Listeria monocytogenes), preventing conjugation. Therefore the tetracycline resistance determinant was transferred via electroporation to L. garvieae. A transformant clone was used as the donor in conjugation experiments with three different L. monocytogenes strains. To our knowledge, this is the first study showing the transfer of an antibiotic resistance plasmid from fish-associated lactic bacteria to L. monocytogenes, even if the donor L. garvieae was not the original host of the tetracycline resistance but experimentally created by electroporation. These results demonstrate that the antibiotic resistance genes in the fish intestinal bacteria have the potential to spread both to fish and human pathogens, posing a risk to aquaculture and consumer safety.

  18. Plasmid-mediated colistin resistance in Escherichia coli from the Arabian Peninsula.

    Science.gov (United States)

    Sonnevend, Ágnes; Ghazawi, Akela; Alqahtani, Manaf; Shibl, Atef; Jamal, Wafa; Hashmey, Rayhan; Pal, Tibor

    2016-09-01

    Searching for the presence of the mcr-1 gene in colistin resistant Enterobacteriaceae in countries of the Arabian Peninsula. Seventy-five independent, colistin resistant Enterobacteriaceae strains isolated from clinical cases in Bahrain, Kuwait, Oman, Saudi Arabia and the United Arab Emirates were tested by PCR for the mcr-1 gene. mcr-1 positive strains were genotyped, and their antibiotic susceptibility was established. The mcr-1 containing plasmids were mobilized into Escherichia coli K-12 and their sequence was determined. Four E. coli isolates (two from Bahrain, one from Saudi Arabia and one from the United Arab Emirates) were identified carrying the mcr-1 gene on conjugative plasmids. They belonged to global multidrug resistant E. coli clones, i.e. ST648, ST224, ST68 and ST131, respectively. One strain carried the blaNDM-1 carbapenemase gene. Three strains carried mcr-1 on IncI2 type plasmids, one of them also harboring a blaCTX-M-64 gene. In the fourth strain mcr-1 was located on a 240kb IncHI2 plasmid co-harboring 13 other resistance genes. This is the first report on the presence of the plasmid-coded mcr-1 gene in a variety of multi-resistant clinical isolates from the Arabian Peninsula indicating that several commonly used antibiotics can potentially facilitate the spread of mcr-1 carrying strains, or directly, mcr-1 containing plasmids. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. Novel Plasmid-Mediated Colistin Resistance Gene mcr-3 in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Wenjuan Yin

    2017-06-01

    Full Text Available The mobile colistin resistance gene mcr-1 has attracted global attention, as it heralds the breach of polymyxins, one of the last-resort antibiotics for the treatment of severe clinical infections caused by multidrug-resistant Gram-negative bacteria. To date, six slightly different variants of mcr-1, and a second mobile colistin resistance gene, mcr-2, have been reported or annotated in the GenBank database. Here, we characterized a third mobile colistin resistance gene, mcr-3. The gene coexisted with 18 additional resistance determinants in the 261-kb IncHI2-type plasmid pWJ1 from porcine Escherichia coli. mcr-3 showed 45.0% and 47.0% nucleotide sequence identity to mcr-1 and mcr-2, respectively, while the deduced amino acid sequence of MCR-3 showed 99.8 to 100% and 75.6 to 94.8% identity to phosphoethanolamine transferases found in other Enterobacteriaceae species and in 10 Aeromonas species, respectively. pWJ1 was mobilized to an E. coli recipient by conjugation and contained a plasmid backbone similar to those of other mcr-1-carrying plasmids, such as pHNSHP45-2 from the original mcr-1-harboring E. coli strain. Moreover, a truncated transposon element, TnAs2, which was characterized only in Aeromonas salmonicida, was located upstream of mcr-3 in pWJ1. This ΔTnAs2-mcr-3 element was also identified in a shotgun genome sequence of a porcine E. coli isolate from Malaysia, a human Klebsiella pneumoniae isolate from Thailand, and a human Salmonella enterica serovar Typhimurium isolate from the United States. These results suggest the likelihood of a wide dissemination of the novel mobile colistin resistance gene mcr-3 among Enterobacteriaceae and aeromonads; the latter may act as a potential reservoir for mcr-3.

  20. Plasmid-mediated colistin resistance in Escherichia coli from the Arabian Peninsula

    Directory of Open Access Journals (Sweden)

    Ágnes Sonnevend

    2016-09-01

    Conclusions: This is the first report on the presence of the plasmid-coded mcr-1 gene in a variety of multi-resistant clinical isolates from the Arabian Peninsula indicating that several commonly used antibiotics can potentially facilitate the spread of mcr-1 carrying strains, or directly, mcr-1 containing plasmids.

  1. Plasmid Mediated Resistance to Cephalosporin and Adhesion Properties in E.Coli

    Directory of Open Access Journals (Sweden)

    Salwa Oufrid

    2014-02-01

    Full Text Available Introduction: The objective of this study is to evaluate the relationship between biofilm formation, surface characteristics and the presence of plasmid conferring resistance to cephalosporin Methodology: The plasmid of resistance of Salmonella 3349 was purified and transferred by electroporation to the E. coli DH10B originally incompetent to form biofilm. The physico-chemical surface properties of the three bacteria (E. coli DH10B, Salmonella 3349 and its isogenic transformant 3519EC1 were estimated and compared by the Microbial Adhesion to Solvents test (MAST and angle contact measurement. Cellular densities of bacteria adhered to stainless supports were examined with a scanning electron microscope. Results: The physicochemical properties of bacterial cell surface demonstrated that E.coli DH10B strain was hydrophilic, electron donating and weakly electron accepting than Salmonella 3349 and its transformant 3519EC1 strains. Moreover, there was a weak correlation between the acid-base properties determined by the Microbial Adhesion to Solvents test and angle contact measurement. Analysis of microscopical images of bacterial adhesion indicated that E.coli 3519EC1 and Salmonella 3349 adhered to the stainless surface, whereas the E.coli DH10B does not adhere. Conclusions: The results of this study suggest that the presences of the plasmid of resistance modify the microbial surface properties and biofilm formation.

  2. Occurrence of (fluoro)quinolones and (fluoro)quinolone resistance in soil receiving swine manure for 11 years.

    Science.gov (United States)

    Xu, Yonggang; Yu, Wantai; Ma, Qiang; Zhou, Hua

    2015-10-15

    Because of the widespread use of antibiotics in animal breeding, the agricultural application of animal manure can lead to the introduction of antibiotics, antibiotic-resistant bacteria and antibiotic resistance genes to the soil and surrounding environment, which may pose a threat to public health. In this study, we investigated the status of (fluoro)quinolone (FQ) residues and FQ resistance levels in soil with and without receiving long-term swine manure. Six FQs (pipemidic acid, lomefloxacin, enrofloxacin, norfloxacin, ciprofloxacin, and ofloxacin) were only detected in manured soil, with individual concentrations ranging from below the detection limit to 27.2 μg kg(-1) and increasing with the increase in swine manure application rates. Higher load rates of swine manure yielded a higher number of ciprofloxacin-resistant (CIPr) bacteria after spreading. A total of 24 CIPr bacterial isolates were obtained from the tested soil, which belonged to four phyla (Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes) or were related to nine different genera. Only 18 isolates from manured soil were positive for five plasmid-mediated quinolone resistance (PMQR) genes (aac(6')-Ib-cr, qnrD, qepA, oqxA, and oqxB). To our knowledge, this study is the first to examine the occurrence of PMQR genes in FQ-resistant bacteria from the soil environment. A similar result was observed for the total DNA from soil, with the exception of aac(6')-Ib being detected in the control sample. The absolute and relative abundances of total PMQR genes also increased with fertilization quantity. Significant correlations were observed between FQ resistance levels and FQ concentrations. These results indicated that the agricultural application of swine manure led to FQ residues and enhanced FQ resistance. This investigation provides baseline data on FQ resistance profiles in soils receiving long-term swine manure. Copyright © 2015. Published by Elsevier B.V.

  3. Prevalence of plasmid mediated pesticide resistant bacterial assemblages in crop fields.

    Science.gov (United States)

    Umamaheswari, S; Murali, M

    2010-11-01

    Three crop fields namely paddy sugarcane and tomato exposed to bavistin [Methyl (1H-benzimidazol-2-yl) carbomate], monocrotophos[Dimethyl(E)-1-methyl-2-(methyl-carbamoyl) vinyl phosphate] and kinado plus [(EZ)-2-chloro-3-dimethoxyphosphinoyloxy-X1, X1-diethylbut-2-enamide], respectively were chosen for the present investigation to know the bacterial population and degradation of pesticides. The chemical nature of the soil and water samples from the pesticide contaminated fields was analysed along with counting of the total heterotrophic bacteria (THB), Staphylococci and Enterococcci population. Mean calcium, phosphate and biological oxygen demand were maximum in tomato field water Field water recorded maximum phophate and silicate content, whereas, sugarcane field water elicited maximum dissolved oxygen content. On the other hand, available phosphate and exchangeable potassium were maximum is sugarcane field soil. Significant variations in the bacterial population were evident between the treatments in sugarcane field soil and tomato field water exposed to monocrotophos and kinado plus, respectively In addition, significant variations between THB, Staphlyococci and Enterococci population were also evinced in both the sugarcane andtomato fields. The dominant pesticide resistant bacteria, Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeuroginosa harboured plasmids and the resistant trait observed were found to be plasmid borne.

  4. Conjugation between quinolone-susceptible bacteria can generate mutations in the quinolone resistance-determining region, inducing quinolone resistance.

    Science.gov (United States)

    Pitondo-Silva, André; Martins, Vinicius Vicente; Silva, Carolina Fávero da; Stehling, Eliana Guedes

    2015-02-01

    Quinolones are an important group of antibacterial agents that can inhibit DNA gyrase and topoisomerase IV activity. DNA gyrase is responsible for maintaining bacteria in a negatively supercoiled state, being composed of subunits A and B. Topoisomerase IV is a homologue of DNA gyrase and consists of two subunits codified by the parC and parE genes. Mutations in gyrA and gyrB of DNA gyrase may confer resistance to quinolones, and the majority of resistant strains show mutations between positions 67 and 106 of gyrA, a region denoted the quinolone resistance-determining region (QRDR). The most frequent substitutions occur at positions 83 and 87, but little is known about the mechanisms promoting appearance of mutations in the QRDR. The present study proposes that some mutations in the QRDR could be generated as a result of the natural mechanism of conjugation between bacteria in their natural habitat. This event was observed following conjugation in vitro of two different isolates of quinolone-susceptible Pseudomonas aeruginosa, which transferred plasmids of different molecular weights to a recipient strain of Escherichia coli (HB101), also quinolone-susceptible, generating two different transconjugants that presented mutations in DNA gyrase and acquisition of resistance to all quinolones tested.

  5. Plasmid-mediated mcr-1 colistin resistance in Escherichia coli and Klebsiella spp. clinical isolates from the Western Cape region of South Africa.

    Science.gov (United States)

    Newton-Foot, Mae; Snyman, Yolandi; Maloba, Motlatji Reratilwe Bonnie; Whitelaw, Andrew Christopher

    2017-01-01

    Colistin is a last resort antibiotic for the treatment of carbapenem-resistant Gram negative infections. Until recently, mechanisms of colistin resistance were limited to chromosomal mutations which confer a high fitness cost and cannot be transferred between organisms. However, a novel plasmid-mediated colistin resistance mechanism, encoded by the mcr-1 gene, has been identified, and has since been detected worldwide. The mcr-1 colistin resistance mechanism is a major threat due to its lack of fitness cost and ability to be transferred between strains and species. Surveillance of colistin resistance mechanisms is critical to monitor the development and spread of resistance.This study aimed to determine the prevalence of the plasmid-mediated colistin resistance gene, mcr-1, in colistin-resistant E. coli and Klebsiella spp. isolates in the Western Cape of South Africa; and whether colistin resistance is spread through clonal expansion or by acquisition of resistance by diverse strains. Colistin resistant E. coli and Klebsiella spp. isolates were collected from the NHLS microbiology laboratory at Tygerberg Hospital. Species identification and antibiotic susceptibility testing was done using the API® 20 E system and the Vitek® 2 Advanced Expert System™. PCR was used to detect the plasmid-mediated mcr-1 colistin resistance gene and REP-PCR was used for strain typing of the isolates. Nineteen colistin resistant isolates, including 12 E. coli, six K. pneumoniae and one K. oxytoca isolate, were detected over 7 months from eight different hospitals in the Western Cape region. The mcr-1 gene was detected in 83% of isolates which were shown to be predominantly unrelated strains. The plasmid-mediated mcr-1 colistin resistance gene is responsible for the majority of colistin resistance in clinical isolates of E. coli and Klebsiella spp. from the Western Cape of South Africa. Colistin resistance is not clonally disseminated; the mcr-1 gene has been acquired by several

  6. Dissemination of a clone carrying a fosA3-harbouring plasmid mediates high fosfomycin resistance rate of KPC-producing Klebsiella pneumoniae in China.

    Science.gov (United States)

    Jiang, Yan; Shen, Ping; Wei, Zeqing; Liu, Lilin; He, Fang; Shi, Keren; Wang, Yanfei; Wang, Haiping; Yu, Yunsong

    2015-01-01

    Fosfomycin has been proposed as an adjunct to other active agents for treating KPC-producing Klebsiella pneumoniae infections. This study aimed to investigate the prevalence of fosfomycin resistance and plasmid-mediated resistance determinants among KPC-producing K. pneumoniae isolates from clinical samples in China. In total, 278 KPC-producing and 80 extended-spectrum β-lactamase (ESBL)-producing (non-KPC-producing) clinical K. pneumoniae isolates were collected in 12 hospitals from 2010 to 2013. Fosfomycin susceptibility testing was carried out using the agar dilution method. Phylogenetic clonal patterns were revealed by pulsed-field gel electrophoresis (PFGE). Isolates were screened for plasmid-mediated fosfomycin resistance genes (fosA, fosA3 and fosC2) by PCR amplification. A plasmid was completely sequenced by next-generation sequencing. The fosfomycin resistance rate in KPC-producers (60.8%; 169/278) was significantly higher than in ESBL-producers (12.5%; 10/80). In addition, 94 KPC-producing isolates were positive for fosA3 and most of them were clonally related. A 23939-bp plasmid (pFOS18) co-harbouring fosA3 and bla(KPC-2) was completely sequenced, revealing that the fosA3 gene was flanked by two copies of IS26; however, bla(KPC-2) was located on a Tn3-Tn4401 integration structure. Although the fosA3 and blaKPC-2 genes are located on different transposon systems, they are able to spread together worldwide through plasmid transfer. Dissemination of the clone carrying the fosA3-harbouring plasmid mediates the high fosfomycin resistance rate of KPC-producing K. pneumoniae in China. Fosfomycin as an alternative option for treating infections caused by KPC-producing K. pneumoniae should not be recommended in hospitals in which fosfomycin-resistant clonal dissemination is emerging.

  7. In vitro activity of Ozenoxacin against quinolone-susceptible and quinolone-resistant gram-positive bacteria.

    Science.gov (United States)

    López, Y; Tato, M; Espinal, P; Garcia-Alonso, F; Gargallo-Viola, D; Cantón, R; Vila, J

    2013-12-01

    In vitro activity of ozenoxacin, a novel nonfluorinated topical (L. D. Saravolatz and J. Leggett, Clin. Infect. Dis. 37:1210-1215, 2003) quinolone, was compared with the activities of other quinolones against well-characterized quinolone-susceptible and quinolone-resistant Gram-positive bacteria. Ozenoxacin was 3-fold to 321-fold more active than other quinolones. Ozenoxacin could represent a first-in-class nonfluorinated quinolone for the topical treatment of a broad range of dermatological infections.

  8. Genotypic characterization of quinolone resistant-Escherichia coli isolates from retail food in Morocco.

    Science.gov (United States)

    Nayme, Kaotar; Barguigua, Abouddihaj; Bouchrif, Brahim; Karraouan, Bouchra; El Otmani, Fatima; Elmdaghri, Naima; Zerouali, Khalid; Timinouni, Mohammed

    2017-02-01

    This study was conducted to assess the retail food as a possible vehicle for antimicrobial resistant, particularly quinolones resistant and pathogenic Escherichia coli. We determined the prevalence and characteristics of nalidixic acid (Nal) resistant E. coli isolates from diverse retail food samples. In all, 70 (28%) of 250 E. coli isolates studied were Nal-resistant E. coli and 91% of these were multi-drug resistant. Plasmid mediated quinolone resistance genes were identified in 32 isolates, including aac(6')-Ib-cr (n = 16), qnrS1 (n = 11) and qnrB19 (n = 7). Mutations in gyr A and par C genes were detected among 80% of the isolates, and the isolates showed substitution Ser83-Leu and Asp87-Asn in gyrA and Ser80-Ile in parC. In addition, three different gene cassettes were identified (aadA1, aadA7, aac(3)-Id) in 18%. Virulence-associated genes stx1, eae, sfa, hlyA and stx2 were found in six (8%), three (4%), two (3%), three (4%) and three (4%) isolates, respectively. E. coli isolates of phylogenetic group A were dominant (64%, 45/70). Pulsed field gel electrophoresis revealed none epidemiological relationship between these isolates. The results of this work report the higher frequency of Nal-resistant E. coli isolates from Moroccan retail food samples including MDR and pathogenic isolates.

  9. Detection of mcr-1 encoding plasmid-mediated colistin-resistant Escherichia coli isolates from human bloodstream infection and imported chicken meat, Denmark 2015.

    Science.gov (United States)

    Hasman, Henrik; Hammerum, Anette M; Hansen, Frank; Hendriksen, Rene S; Olesen, Bente; Agersø, Yvonne; Zankari, Ea; Leekitcharoenphon, Pimlapas; Stegger, Marc; Kaas, Rolf S; Cavaco, Lina M; Hansen, Dennis S; Aarestrup, Frank M; Skov, Robert L

    2015-01-01

    The plasmid-mediated colistin resistance gene, mcr-1, was detected in an Escherichia coli isolate from a Danish patient with bloodstream infection and in five E. coli isolates from imported chicken meat. One isolate from chicken meat belonged to the epidemic spreading sequence type ST131. In addition to IncI2, an incX4 replicon was found to be linked to mcr-1. This report follows a recent detection of mcr-1 in E. coli from animals, food and humans in China.

  10. The presence of plasmid-mediated resistance genes among uropathogenes isolated from diabetic and non-diabetic patients with chronic pyelonephritis

    Directory of Open Access Journals (Sweden)

    O.I. Chub

    2016-08-01

    Full Text Available Increased multidrug resistance of extended-spectrum beta-lactamases (ESBLs compromises the efficacy of treatment of urinary tract infections. The objective of this study is to determine the prevalence of ESBL-producing uropathogens from patients with chronic pyelonephritis (CP and to evaluate the risk factors of these types of infections. Screening for the presence of plasmid-mediated ESBL was performed by polymerase chain reaction. Out of 105 patients, 22 (20.9% revealed strains with resistance genes: 11 (36.7%, 11 (36.7% and 8 (26.7% were identified to carry bla(TEM, bla(SHV and bla(CTX-M beta-lactamase genes, respectively. We have demonstrated that prevalence of the resistance among patients with CP combined with type 2 DM was 31.3%, while among patients with CP without type 2 DM was 27.4%; however the difference between these groups was not significant. The main factors related with appearance of plasmid-mediated resistance genes were age range above 55 years, Chronic Kidney Disease stage ІІІ and ІV, in-patient treatment history, history of using antibiotics last year. Isolation and detection of ESBL-producing strains are essential fоr the sеlection оf the mоst effеctive antibiоtic for the empiric trеatment.

  11. Characteristics of Quinolone Resistance in Salmonella spp. Isolates from the Food Chain in Brazil.

    Science.gov (United States)

    Pribul, Bruno R; Festivo, Marcia L; Rodrigues, Marcelle S; Costa, Renata G; Rodrigues, Elizabeth C Dos P; de Souza, Miliane M S; Rodrigues, Dalia Dos P

    2017-01-01

    Salmonella spp. is an important zoonotic pathogen related to foodborne diseases. Despite that quinolones/fluoroquinolones are considered a relevant therapeutic strategy against resistant isolates, the increase in antimicrobial resistance is an additional difficulty in controlling bacterial infections caused by Salmonella spp. Thus, the acquisition of resistance to quinolones in Salmonella spp. is worrisome to the scientific community along with the possibility of transmission of resistance through plasmids. This study investigated the prevalence of plasmid-mediated quinolone resistance (PMQR) in Salmonella spp. and its association with fluoroquinolone susceptibility in Brazil. We evaluated 129 isolates, 39 originated from food of animal sources, and 14 from environmental samples and including 9 from animals and 67 from humans, which were referred to the National Reference Laboratory of Enteric Diseases (NRLEB/IOC/RJ) between 2009 and 2013. These samples showed a profile of resistance for the tested quinolones/fluoroquinolones. A total of 33 serotypes were identified; S. Typhimurium (63) was the most prevalent followed by S. Enteritidis (25). The disk diffusion test showed 48.8% resistance to enrofloxacin, 42.6% to ciprofloxacin, 39.53% to ofloxacin, and 30.2% to levofloxacin. According to the broth microdilution test, the resistance percentages were: 96.1% to nalidixic acid, 64.3% to enrofloxacin, 56.6% to ciprofloxacin, 34.1% to ofloxacin, and 30.2% to levofloxacin. Qnr genes were found in 15 isolates (8 qnrS, 6 qnrB, and 1 qnrD), and the aac(6')-Ib gene in 23. The integron gene was detected in 67 isolates with the variable region between ±600 and 1000 bp. The increased detection of PMQR in Salmonella spp. is a serious problem in Public Health and must constantly be monitored. Pulsed-field gel electrophoresis was performed to evaluated clonal profile among the most prevalent serovars resistant to different classes of quinolones. A total of 33 pulsotypes of S

  12. The Current Case of Quinolones: Synthetic Approaches and Antibacterial Activity

    Directory of Open Access Journals (Sweden)

    Abdul Naeem

    2016-03-01

    Full Text Available Quinolones are broad-spectrum synthetic antibacterial drugs first obtained during the synthesis of chloroquine. Nalidixic acid, the prototype of quinolones, first became available for clinical consumption in 1962 and was used mainly for urinary tract infections caused by Escherichia coli and other pathogenic Gram-negative bacteria. Recently, significant work has been carried out to synthesize novel quinolone analogues with enhanced activity and potential usage for the treatment of different bacterial diseases. These novel analogues are made by substitution at different sites—the variation at the C-6 and C-8 positions gives more effective drugs. Substitution of a fluorine atom at the C-6 position produces fluroquinolones, which account for a large proportion of the quinolones in clinical use. Among others, substitution of piperazine or methylpiperazine, pyrrolidinyl and piperidinyl rings also yields effective analogues. A total of twenty six analogues are reported in this review. The targets of quinolones are two bacterial enzymes of the class II topoisomerase family, namely gyrase and topoisomerase IV. Quinolones increase the concentration of drug-enzyme-DNA cleavage complexes and convert them into cellular toxins; as a result they are bactericidal. High bioavailability, relative low toxicity and favorable pharmacokinetics have resulted in the clinical success of fluoroquinolones and quinolones. Due to these superior properties, quinolones have been extensively utilized and this increased usage has resulted in some quinolone-resistant bacterial strains. Bacteria become resistant to quinolones by three mechanisms: (1 mutation in the target site (gyrase and/or topoisomerase IV of quinolones; (2 plasmid-mediated resistance; and (3 chromosome-mediated quinolone resistance. In plasmid-mediated resistance, the efflux of quinolones is increased along with a decrease in the interaction of the drug with gyrase (topoisomerase IV. In the case of

  13. The Current Case of Quinolones: Synthetic Approaches and Antibacterial Activity.

    Science.gov (United States)

    Naeem, Abdul; Badshah, Syed Lal; Muska, Mairman; Ahmad, Nasir; Khan, Khalid

    2016-03-28

    Quinolones are broad-spectrum synthetic antibacterial drugs first obtained during the synthesis of chloroquine. Nalidixic acid, the prototype of quinolones, first became available for clinical consumption in 1962 and was used mainly for urinary tract infections caused by Escherichia coli and other pathogenic Gram-negative bacteria. Recently, significant work has been carried out to synthesize novel quinolone analogues with enhanced activity and potential usage for the treatment of different bacterial diseases. These novel analogues are made by substitution at different sites--the variation at the C-6 and C-8 positions gives more effective drugs. Substitution of a fluorine atom at the C-6 position produces fluroquinolones, which account for a large proportion of the quinolones in clinical use. Among others, substitution of piperazine or methylpiperazine, pyrrolidinyl and piperidinyl rings also yields effective analogues. A total of twenty six analogues are reported in this review. The targets of quinolones are two bacterial enzymes of the class II topoisomerase family, namely gyrase and topoisomerase IV. Quinolones increase the concentration of drug-enzyme-DNA cleavage complexes and convert them into cellular toxins; as a result they are bactericidal. High bioavailability, relative low toxicity and favorable pharmacokinetics have resulted in the clinical success of fluoroquinolones and quinolones. Due to these superior properties, quinolones have been extensively utilized and this increased usage has resulted in some quinolone-resistant bacterial strains. Bacteria become resistant to quinolones by three mechanisms: (1) mutation in the target site (gyrase and/or topoisomerase IV) of quinolones; (2) plasmid-mediated resistance; and (3) chromosome-mediated quinolone resistance. In plasmid-mediated resistance, the efflux of quinolones is increased along with a decrease in the interaction of the drug with gyrase (topoisomerase IV). In the case of chromosome

  14. Detection of plasmid mediated colistin resistance (MCR-1) in Escherichia coli and Salmonella enterica isolated from poultry and swine in Spain.

    Science.gov (United States)

    Quesada, Alberto; Ugarte-Ruiz, María; Iglesias, M Rocío; Porrero, M Concepción; Martínez, Remigio; Florez-Cuadrado, Diego; Campos, María J; García, María; Píriz, Segundo; Sáez, José Luis; Domínguez, Lucas

    2016-04-01

    Recent findings suggest that use of colistin as a last resort antibiotic is seriously threatened by the rise of a new plasmid mediated mechanism of resistance (MCR-1). This work identifies, for the first time in Southern Europe, the gene mcr-1 in nine strains from farm animals (poultry and swine) corresponding to five Escherichia coli and four Salmonella enterica, among which three belong to serovar Typhimurium and one to Rissen. The MCR-1 was found encoded by a plasmid highly mobilizable by conjugation to the E. coli J53 strain. Two E. coli strains carried two determinants, mcr-1 plus pmrA or pmrB mutations, known to confer colistin resistance.

  15. Real-time quantitative PCR assay with Taqman® probe for rapid detection of MCR-1 plasmid-mediated colistin resistance

    Directory of Open Access Journals (Sweden)

    S. Chabou

    2016-09-01

    Full Text Available Here we report the development of two rapid real-time quantitative PCR assays with TaqMan® probes to detect the MCR-1 plasmid-mediated colistin resistance gene from bacterial isolates and faecal samples from chickens. Specificity and sensitivity of the assay were 100% on bacterial isolates including 18 colistin-resistant isolates carrying the mcr-1 gene (six Klebsiella pneumoniae and 12 Escherichia coli with a calibration curve that was linear from 101 to 108 DNA copies. Five out of 833 faecal samples from chickens from Algeria were positive, from which three E. coli strains were isolated and confirmed to harbour the mcr-1 gene by standard PCR and sequencing.

  16. Characterization of quinolone resistance mechanisms in Enterobacteriaceae recovered from diseased companion animals in Europe.

    Science.gov (United States)

    Guillard, T; de Jong, A; Limelette, A; Lebreil, A L; Madoux, J; de Champs, C

    2016-10-15

    ComPath is a European monitoring programme dedicated to the collection of bacterial pathogens from diseased dogs and cats to determine their antibiotic susceptibility. The objective was to characterize genetic determinants associated with quinolone resistance among 69 enrofloxacin non-wild type strains selected among 604 non-duplicate Enterobacteriaceae isolates collected in 10EU countries from 2008 to 2010: quinolone resistance determining region (QRDR) and plasmid-mediated quinolone resistance (PMQR). Among them, 17% (12/69) carried at least one PMQR (9/12 qnrB, qnrS or qnrD and 4/12 aac(6')-Ib-cr) and 83% (57/69) no PMQR. All the Klebsiella pneumoniae isolates chromosomally carried oqxAB . No qepA genes were detected. Eight strains did not carry any mutations in QRDR (4 PMQR-positive and 4 PMQR-negative strains). From the 12 PMQR-positive strains, 4 showed enrofloxacin MICs≤2μg/mL, and 8 MICs≥8μg/mL (resistant). These latter strains carried 1-5 mutations in QRDR, including a ParE I529L mutation. qnrD was found in 2 Proteus mirabilis and the plasmids were similar to pDIJ09-518a previously described. For the 57 non-PMQR strains, 29 strains showed MICs≤2μg/mL (4 with no QRDR mutations, 21 with 1 mutation in GyrA, 4 with 2 mutations in GyrA) and 28 showed enrofloxacin MICs≥8μg/mL carrying at least 2 mutations in QRDR, including a ParE I529L mutation for 2 Escherichia coli strains with a total of 5 QRDR mutations. No GyrB mutations were found. qnr was the major PMQR and qnrD was only detected in Proteus spp. Twelve strains carried at least 4 mutations.

  17. A molecular analysis of quinolone-resistant Haemophilus influenzae: validation of the mutations in Quinolone Resistance-Determining Regions.

    Science.gov (United States)

    Shoji, Hisashi; Shirakura, Tetsuro; Fukuchi, Kunihiko; Takuma, Takahiro; Hanaki, Hideaki; Tanaka, Kazuo; Niki, Yoshihito

    2014-04-01

    The mechanism of quinolone-resistance is considered to be amino acid mutations in the type II topoisomerase. We validated the genetic mechanisms of quinolone resistance in Haemophilus influenzae. We obtained 29 H. influenzae strains from a nationwide surveillance program in Japan (including 11 quinolone-resistant strains [moxifloxacin: MFLX or levofloxacin MIC ≥2 μg/ml]). We analyzed the sequences of the Quinolone Resistance-Determining Regions (QRDRs) in GyrA, GyrB, ParC and ParE. Furthermore, we induced resistance in susceptible strains by exposing them to quinolone, and investigated the relationship between mutations in the QRDRs and the MICs. Five amino acid substitutions in GyrA (at Ser84 and Asp88) and ParC (at Gly82, Ser84 and Glu88) were found to be closely related to the MICs. The strains with a MFLX MIC of 0.125-1 and 2-4 μg/ml had one and two mutations, respectively. The strains with a MFLX MIC of ≥8 μg/ml had three or more mutations. The strains with induced resistance with MFLX MICs of 0.5-1 and ≥2 μg/ml also had one and two mutations, respectively. We confirmed that these five mutations strongly contribute to quinolone resistance and found that the degree of resistance is related to the number of the mutations. In addition, the three strains of 18 susceptible strains (16.7%) also had a single mutation. These strains may therefore be in the initial stage of quinolone resistance. Currently, the frequency of quinolone-resistant H. influenzae is still low. However, as has occurred with β-lactams, an increase in quinolone use may lead to more quinolone-resistant strains.

  18. [Prevalence of quinolone resistance mechanisms in Enterobacteriaceae producing acquired AmpC β-lactamases and/or carbapenemases in Spain].

    Science.gov (United States)

    Machuca, Jesús; Agüero, Jesús; Miró, Elisenda; Conejo, María Del Carmen; Oteo, Jesús; Bou, Germán; González-López, Juan José; Oliver, Antonio; Navarro, Ferran; Pascual, Álvaro; Martínez-Martínez, Luis

    2016-06-23

    Quinolone resistance in Enterobacteriaceae species has increased over the past few years, and is significantly associated to beta-lactam resistance. The aim of this study was to evaluate the prevalence of chromosomal- and plasmid-mediated quinolone resistance in acquired AmpC β-lactamase and/or carbapenemase-producing Enterobacteriaceae isolates. The presence of chromosomal- and plasmid-mediated quinolone resistance mechanisms [mutations in the quinolone resistance determining region (QRDR) of gyrA and parC and qnr, aac(6')-Ib-cr and qepA genes] was evaluated in 289 isolates of acquired AmpC β-lactamase- and/or carbapenemase-producing Enterobacteriaceae collected between February and July 2009 in 35 Spanish hospitals. Plasmid mediated quinolone resistance (PMQR) genes were detected in 92 isolates (31.8%), qnr genes were detected in 83 isolates (28.7%), and the aac(6')-Ib-cr gene was detected in 20 isolates (7%). qnrB4 gene was the most prevalent qnr gene detected (20%), associated, in most cases, with DHA-1. Only 14.6% of isolates showed no mutations in gyrA or parC with a ciprofloxacin MIC of 0.5mg/L or higher, whereas PMQR genes were detected in 90% of such isolates. qnrB4 gene was the most prevalent PMQR gene detected, and was significantly associated with acquired AmpC β-lactamase DHA-1. PMQR determinants in association with other chromosomal-mediated quinolone resistance mechanisms, different to mutations in gyrA and parC (increased energy-dependent efflux, altered lipopolysaccharide or porin loss), could lead to ciprofloxacin MIC values that exceed breakpoints established by the main international committees to define clinical antimicrobial susceptibility breakpoints. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

  19. Apigenin as an anti-quinolone-resistance antibiotic.

    Science.gov (United States)

    Morimoto, Yuh; Baba, Tadashi; Sasaki, Takashi; Hiramatsu, Keiichi

    2015-12-01

    We previously reported the first 'reverse antibiotic' (RA), nybomycin (NYB), which showed a unique antimicrobial activity against Staphylococcus aureus strains. NYB specifically suppressed the growth of quinolone-resistant S. aureus strains but was not effective against quinolone-susceptible strains. Although NYB was first reported in 1955, little was known about its unique antimicrobial activity because it was before the synthesis of the first quinolone ('old quinolone'), nalidixic acid, in 1962. Following our re-discovery of NYB, we looked for other RAs among natural substances that act on quinolone-resistant bacteria. Commercially available flavones were screened against S. aureus, including quinolone-resistant strains, and their minimum inhibitory concentrations (MICs) were compared using the microbroth dilution method. Some of the flavones screened showed stronger antimicrobial activity against quinolone-resistant strains than against quinolone-susceptible ones. Amongst them, apigenin (API) was the most potent in its RA activity. DNA cleavage assay showed that API inhibited DNA gyrase harbouring the quinolone resistance mutation gyrA(Ser84Leu) but did not inhibit 'wild-type' DNA gyrase that is sensitive to levofloxacin. An API-susceptible S. aureus strain Mu50 was also selected using agar plates containing 20mg/L API. Whole-genome sequencing of selected mutant strains was performed and frequent back-mutations (reverse mutations) were found among API-resistant strains derived from the API-susceptible S. aureus strains. Here we report that API represents another molecular class of natural antibiotic having RA activity against quinolone-resistant bacteria.

  20. Quinolone co-resistance in ESBL- or AmpC-producing Escherichia coli from an Indian urban aquatic environment and their public health implications.

    Science.gov (United States)

    Bajaj, Priyanka; Kanaujia, Pawan Kumar; Singh, Nambram Somendro; Sharma, Shalu; Kumar, Shakti; Virdi, Jugsharan Singh

    2016-01-01

    Quinolone and β-lactam antibiotics constitute major mainstay of treatment against infections caused by pathogenic Escherichia coli. Presence of E. coli strains expressing co-resistance to both these antibiotic classes in urban aquatic environments which are consistently being used for various anthropogenic activities represents a serious public health concern. From a heterogeneous collection of 61 E. coli strains isolated from the river Yamuna traversing through the National Capital Territory of Delhi (India), those harboring blaCTX-M-15 (n = 10) or blaCMY-42 (n = 2) were investigated for co-resistance to quinolones and the molecular mechanisms thereof. Resistance was primarily attributed to amino acid substitutions in the quinolone resistance-determining regions (QRDRs) of GyrA (S83L ± D87N) and ParC (S80I ± E84K). One of the E. coli strains, viz., IPE, also carried substitutions in GyrB and ParE at positions Ser492→Asn and Ser458→Ala, respectively. The phenotypically susceptible strains nevertheless carried plasmid-mediated quinolone resistance (PMQR) gene, viz., qnrS, which showed co-transfer to the recipient quinolone-sensitive E. coli J53 along with the genes encoding β-lactamases and led to increase in minimal inhibitory concentrations of quinolone antibiotics. To the best of our knowledge, this represents first report of molecular characterization of quinolone co-resistance in E. coli harboring genes for ESBLs or AmpC β-lactamases from a natural aquatic environment of India. The study warrants true appreciation of the potential of urban aquatic environments in the emergence and spread of multi-drug resistance and underscores the need to characterize resistance genetic elements vis-à-vis their public health implications, irrespective of apparent phenotypic resistance.

  1. Comparison of two DNA microarrays for detection of plasmid-mediated antimicrobial resistance and virulence factor genes in clinical isolates of Enterobacteriaceae and non-Enterobacteriaceae.

    LENUS (Irish Health Repository)

    Walsh, Fiona

    2010-06-01

    A DNA microarray was developed to detect plasmid-mediated antimicrobial resistance (AR) and virulence factor (VF) genes in clinical isolates of Enterobacteriaceae and non-Enterobacteriaceae. The array was validated with the following bacterial species: Escherichiacoli (n=17); Klebsiellapneumoniae (n=3); Enterobacter spp. (n=6); Acinetobacter genospecies 3 (n=1); Acinetobacterbaumannii (n=1); Pseudomonasaeruginosa (n=2); and Stenotrophomonasmaltophilia (n=2). The AR gene profiles of these isolates were identified by polymerase chain reaction (PCR). The DNA microarray consisted of 155 and 133 AR and VF gene probes, respectively. Results were compared with the commercially available Identibac AMR-ve Array Tube. Hybridisation results indicated that there was excellent correlation between PCR and array results for AR and VF genes. Genes conferring resistance to each antibiotic class were identified by the DNA array. Unusual resistance genes were also identified, such as bla(SHV-5) in a bla(OXA-23)-positive carbapenem-resistant A. baumannii. The phylogenetic group of each E. coli isolate was verified by the array. These data demonstrate that it is possible to screen simultaneously for all important classes of mobile AR and VF genes in Enterobacteriaceae and non-Enterobacteriaceae whilst also assigning a correct phylogenetic group to E. coli isolates. Therefore, it is feasible to test clinical Gram-negative bacteria for all known AR genes and to provide important information regarding pathogenicity simultaneously.

  2. Insights into the Mechanistic Basis of Plasmid-Mediated Colistin Resistance from Crystal Structures of the Catalytic Domain of MCR-1

    Science.gov (United States)

    Hinchliffe, Philip; Yang, Qiu E.; Portal, Edward; Young, Tom; Li, Hui; Tooke, Catherine L.; Carvalho, Maria J.; Paterson, Neil G.; Brem, Jürgen; Niumsup, Pannika R.; Tansawai, Uttapoln; Lei, Lei; Li, Mei; Shen, Zhangqi; Wang, Yang; Schofield, Christopher J.; Mulholland, Adrian J; Shen, Jianzhong; Fey, Natalie; Walsh, Timothy R.; Spencer, James

    2017-01-01

    The polymixin colistin is a “last line” antibiotic against extensively-resistant Gram-negative bacteria. Recently, the mcr-1 gene was identified as a plasmid-mediated resistance mechanism in human and animal Enterobacteriaceae, with a wide geographical distribution and many producer strains resistant to multiple other antibiotics. mcr-1 encodes a membrane-bound enzyme catalysing phosphoethanolamine transfer onto bacterial lipid A. Here we present crystal structures revealing the MCR-1 periplasmic, catalytic domain to be a zinc metalloprotein with an alkaline phosphatase/sulphatase fold containing three disulphide bonds. One structure captures a phosphorylated form representing the first intermediate in the transfer reaction. Mutation of residues implicated in zinc or phosphoethanolamine binding, or catalytic activity, restores colistin susceptibility of recombinant E. coli. Zinc deprivation reduces colistin MICs in MCR-1-producing laboratory, environmental, animal and human E. coli. Conversely, over-expression of the disulphide isomerase DsbA increases the colistin MIC of laboratory E. coli. Preliminary density functional theory calculations on cluster models suggest a single zinc ion may be sufficient to support phosphoethanolamine transfer. These data demonstrate the importance of zinc and disulphide bonds to MCR-1 activity, suggest that assays under zinc-limiting conditions represent a route to phenotypic identification of MCR-1 producing E. coli, and identify key features of the likely catalytic mechanism. PMID:28059088

  3. Increasing quinolone resistance in Salmonella enterica serotype enteritidis

    DEFF Research Database (Denmark)

    Mølbak, K.; Gerner-Smidt, P.; Wegener, Henrik Caspar

    2002-01-01

    Until recently, Salmonella enterica serotype Enteritidis has remained sensitive to most antibiotics. However, national surveillance data from Denmark show that quinolone resistance in S. Enteritidis has increased from 0.8% in 1995 to 8.5% in 2000. These data support concerns that the current use...... of quinolone in food animals leads to increasing resistance in S. Enteritidis and that action should be taken to limit such use....

  4. Multidrug Resistance in Quinolone-Resistant Gram-Negative Bacteria Isolated from Hospital Effluent and the Municipal Wastewater Treatment Plant.

    Science.gov (United States)

    Vaz-Moreira, Ivone; Varela, Ana Rita; Pereira, Thamiris V; Fochat, Romário C; Manaia, Célia M

    2016-03-01

    This study is aimed to assess if hospital effluents represent an important supplier of multidrug-resistant (MDR) Gram-negative bacteria that, being discharged in the municipal collector, may be disseminated in the environment and bypassed in water quality control systems. From a set of 101 non-Escherichia coli Gram-negative bacteria with reduced susceptibility to quinolones, was selected a group of isolates comprised by those with the highest indices of MDR (defined as nonsusceptibility to at least one agent in six or more antimicrobial categories, MDR ≥6) or resistance to meropenem or ceftazidime (n = 25). The isolates were identified and characterized for antibiotic resistance phenotype, plasmid-mediated quinolone resistance (PMQR) genes, and other genetic elements and conjugative capacity. The isolates with highest MDR indices were mainly from hospital effluent and comprised ubiquitous bacterial groups of the class Gammaproteobacteria, of the genera Aeromonas, Acinetobacter, Citrobacter, Enterobacter, Klebsiella, and Pseudomonas, and of the class Flavobacteriia, of the genera Chryseobacterium and Myroides. In this group of 25 strains, 19 identified as Gammaproteobacteria harbored at least one PMQR gene (aac(6')-Ib-cr, qnrB, qnrS, or oqxAB) or a class 1 integron gene cassette encoding aminoglycoside, sulfonamide, or carbapenem resistance. Most of the E. coli J53 transconjugants with acquired antibiotic resistance resulted from conjugation with Enterobacteriaceae. These transconjugants demonstrated acquired resistance to a maximum of five classes of antibiotics, one or more PMQR genes and/or a class 1 integron gene cassette. This study shows that ubiquitous bacteria, other than those monitored in water quality controls, are important vectors of antibiotic resistance and can be disseminated from hospital effluent to aquatic environments. This information is relevant to support management options aiming at the control of this public health problem.

  5. Plasmid mediated antibiotic resistance ofVibrio cholerae O1 biotype El Tor serotype Ogawa associated with an outbreak in Kolkata, India

    Institute of Scientific and Technical Information of China (English)

    Shyamapada Mandal; Manisha DebMandal; Nishith Kumar Pal

    2010-01-01

    Objective:To determine the antibiotic resistance ofVibrio cholerae (V. cholerae)O1 biotype El Tor serotype Ogawa isolates involved in an outbreak of watery diarrhea in Kolkata, and to explore the role of plasmid in mediating antibiotic resistance.Methods: Antibiotic susceptibility and minimum inhibitory concentration(MIC) values of antibiotics for the isolated V. choleraeO1 Ogawa (n=12) were determined by disk diffusion and agar dilution methods, respectively, using ampicillin (Am), chloramphenicol (C), trimethoprim (Tm), tetracycline (T), erythromycine (Er), nalidixic acid (Nx), ciprofloxacin (Cp), amikacin (Ak) and cefotaxime (Cf). Plasmid curing of multidrug resistant(MDR)V. choleraeO1 Ogawa strains was done following ethidium bromide treatment. Following electrophoresis, the plasmidDNAs, extracted from the isolatedMDRV. choleraeO1 Ogawa strains and their cured derivatives, were visualized and documented in‘gel doc’ system.Results: The outbreak causingV. choleraeO1 Ogawa isolates wereMDR as determined by disk diffusion susceptibility test, andMIC determination. The isolates showed three different drug resistance patterns: AmTmTErNx (for6 isolates), TmTErCp (for 5 isolates), and AmTmNx (for one isolate), and showed uniform sensitivity to C, Ak and Cf. The loss of plasmids with the concomitant loss of resistance to Am, Tm, T and Er of the isolates occurred following ethidium bromide treatment.Conclusions: The current findings suggest that theV. choleraeO1Ogawa associated with the cholera outbreak wereMDR, and resistance to Am, Tm, T and Er among the isolates were plasmid mediated.

  6. Emergence of co-production of plasmid-mediated AmpC beta-lactamase and ESBL in cefoxitin-resistant uropathogenic Escherichia coli.

    Science.gov (United States)

    Ghosh, B; Mukherjee, M

    2016-09-01

    Plasmid-mediated AmpC (pAmpC) and ESBL co-production was detected in Escherichia coli a major etiologic agent of urinary tract infection. Isolates resistant to cefoxitin by CLSI methodology were tested for pAmpC beta-lactamase using phenylboronic acid and ESBLs by combined disk diffusion method. pAmpC/ESBL genes were characterized by PCR and sequencing. Transconjugation experiments were done to study the transfer of pAmpC and ESBL production from clinical isolates as donor to E. coli J53 AziR as recipient. Incompatibility groups of transmissible plasmids were classified by PCR-based replicon typing (PBRT). Among 148 urine culture positive isolates, E. coli was reported in 39.86 % (59/148), with 93.22 % (55/59) of cefoxitin resistance. pAmpC production was detected in 25, with varied distribution of blaCMY-2 and blaDHA-1type genes alone (n = 13 and 7 respectively) or in combination (n = 5). ESBL co-production was observed in 88 % (22/25) of pAmpC producing isolates with predominance of blaTEM (n = 20). Twenty-three transconjugants showed transmission of pAmpC-and ESBL-resistant genes with co-carriage of blaCMY-2 and blaTEM (n = 15) in plasmids of IncF type (n = 9) being predominant, followed by IncI1 (n = 4) and IncH1 (n = 2) in combination. All clinical isolates were clonally diverse. Resistance against different beta-lactams in uropathogenic E. coli has been an emerging concern in resource- poor countries such as India. Knowledge on the occurrence of AmpC beta-lactamases and ESBL amongst this pathogen and its transmission dynamics may aid in hospital infection control.

  7. How should we respond to the emergence of plasmid-mediated colistin resistance in humans and animals?

    Directory of Open Access Journals (Sweden)

    Jaffar A. Al-Tawfiq

    2017-01-01

    Conclusion: The emergence and horizontal transmission of colistin resistance highlights the need for heightened stewardship efforts across the One Health platform for this antibiotic of last resort, and indeed for all antibiotics used in animals and humans.

  8. Travelers Can Import Colistin-Resistant Enterobacteriaceae, Including Those Possessing the Plasmid-Mediated mcr-1 Gene.

    Science.gov (United States)

    Bernasconi, Odette J; Kuenzli, Esther; Pires, João; Tinguely, Regula; Carattoli, Alessandra; Hatz, Christoph; Perreten, Vincent; Endimiani, Andrea

    2016-08-01

    Stool samples from 38 travelers returning from India were screened for extended-spectrum cephalosporin- and carbapenem-resistant Enterobacteriaceae implementing standard selective plates. Twenty-six (76.3%) people were colonized with CTX-M or DHA producers, but none of the strains was colistin resistant and/or mcr-1 positive. Nevertheless, using overnight enrichment and CHROMagar Orientation plates supplemented with colistin, four people (10.5%) were found to be colonized with colistin-resistant Escherichia coli One cephalosporin-susceptible sequence type 10 (ST10) strain carried a 4,211-bp ISApl1-mcr-1-ISApl1 element in an IncHI2 plasmid backbone. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  9. Plasmid mediated multiple antibiotic resistance in Escherichia coli isolated from community acquired infection of urinary tract in Aligarh Hospital

    Institute of Scientific and Technical Information of China (English)

    Asad U Khan; Saeedut Zafar Ali; Mohammed S Zaman

    2008-01-01

    This study was to investigate the current trends of multiple drug resistance in bacteria against antibiotics for the proper empirical treatmen.Clinical isolates were collected from community-acquired infection of urinary tract patients in Aligarh India from March 1999 to August 1999.Antibiotic susceptibility test was performed,using the disc diffusion method followed by plasmid isolation by the method of Kado and Liu.Transfer experiments were performed by the method of Lederberg and Cohen.Clinical study revealed that this infection was more common in young women.Various strains of E.coli isolated during the course of study were found to show multiple antibiotic resistance which was further characterized as plasmid-borne drug resistance.This study shows that E.coli may be one of the important causative agents of urinary tract infection (UTI )in young women.

  10. Emergence of plasmid-mediated colistin resistance (MCR-1) among Escherichia coli isolated from South African patients.

    Science.gov (United States)

    Coetzee, Jennifer; Corcoran, Craig; Prentice, Elizabeth; Moodley, Mischka; Mendelson, Marc; Poirel, Laurent; Nordmann, Patrice; Brink, Adrian John

    2016-04-19

    The polymyxin antibiotic colistin is an antibiotic of last resort for the treatment of extensively drug-resistant Gram-negative bacteria, including carbapenemase-producing Enterobacteriaceae. The State of the World's Antibiotics report in 2015 highlighted South Africa (SA)'s increasing incidence of these 'superbugs' (3.2% of Klebsiella pneumoniae reported from SA were carbapenemase producers), and in doing so, underscored SA's increasing reliance on colistin as a last line of defence. Colistin resistance effectively renders such increasingly common infections untreatable.

  11. Plasmid-mediated resistance to tetracyclines among Neisseria gonorrhoeae strains isolated in Poland between 2012 and 2013

    Science.gov (United States)

    Młynarczyk-Bonikowska, Beata; Kujawa, Marlena; Malejczyk, Magdalena; Młynarczyk, Grażyna

    2016-01-01

    Introduction One of two main mechanisms of resistance in tetracycline-resistant Neisseria gonorrhoeae (TRNG) is associated with the presence of TetM protein responsible for actively blocking of the tetracycline target site in the 30S ribosomal subunit. This mechanism is encoded by conjugative plasmids. The second mechanism is chromosomal in nature and due to mutations in specific genes. Aim To determine the incidence and type of tetM determinants in TRNG strains isolated from patients presenting with gonorrhea infection to the Dermatology and Venereology Clinic in Warsaw in 2012–2013. Material and methods Tetracycline and doxycycline susceptibility was determined by E-Tests. The presence and type of the tetM gene were determined by polymerase chain reaction. Results Tetracycline resistance was detected in 50.8% of the evaluated strains. The TRNG strains containing the tetM plasmid constituted 13.8% of all the evaluated strains. Dutch type tetM constituted 12.3% and American type tetM 1.5% of all the evaluated strains. In the remaining TRNG strains, resistance to tetracyclines was presumably chromosome-encoded. The minimal inhibitory concentration (MIC) of tetracycline ranged from 0.25 to 32.0 mg/l, MIC50 = 2.0 mg/l, MIC90 = 32.0 mg/l. The MIC of doxycycline ranged from 0.25 to 32.0 mg/l, MIC50 = 4.0 mg/l, MIC90 = 16.0 mg/l. Conclusions Unlike most of European countries, in 2012–2013 in Poland, the Dutch type tetM was found to be much more common than the American type. Minimal inhibitory concentration values of tetracycline and doxycycline were similar, with doxycycline exhibiting a somewhat lower effectiveness in vitro than tetracycline towards chromosome-mediated tetracycline resistant strains of N. gonorrhoeae. PMID:28035227

  12. Detection of the plasmid-mediated mcr-1 gene conferring colistin resistance in human and food isolates of Salmonella enterica and Escherichia coli in England and Wales.

    Science.gov (United States)

    Doumith, Michel; Godbole, Gauri; Ashton, Philip; Larkin, Lesley; Dallman, Tim; Day, Martin; Day, Michaela; Muller-Pebody, Berit; Ellington, Matthew J; de Pinna, Elizabeth; Johnson, Alan P; Hopkins, Katie L; Woodford, Neil

    2016-08-01

    In response to the first report of transmissible colistin resistance mediated by the mcr-1 gene in Escherichia coli and Klebsiella spp. from animals and humans in China, we sought to determine its presence in Enterobacteriaceae isolated in the UK. The PHE archive of whole-genome sequences of isolates from surveillance collections, submissions to reference services and research projects was retrospectively analysed for the presence of mcr-1 using Genefinder. The genetic environment of the gene was also analysed. Rapid screening of the genomes of ∼24 000 Salmonella enterica, E. coli, Klebsiella spp., Enterobacter spp., Campylobacter spp. and Shigella spp. isolated from food or humans identified 15 mcr-1-positive isolates. These comprised: 10 human S. enterica isolates submitted between 2012 and 2015 (8 Salmonella Typhimurium, 1 Salmonella Paratyphi B var Java and 1 Salmonella Virchow) from 10 patients; 3 isolates of E. coli from 2 patients; and 2 isolates of Salmonella Paratyphi B var Java from poultry meat imported from the EU. The mcr-1 gene was located on diverse plasmids belonging to the IncHI2, IncI2 and IncX4 replicon types and its association with ISApl1 varied. Six mcr-1-positive S. enterica isolates were from patients who had recently travelled to Asia. Analysis of WGS data allowed rapid confirmation of the presence of the plasmid-mediated colistin resistance gene mcr-1 in diverse genetic environments and plasmids. It has been present in E. coli and Salmonella spp. harboured by humans in England and Wales since at least 2012. © Crown copyright 2016.

  13. Topoisomerase IV-quinolone interactions are mediated through a water-metal ion bridge: mechanistic basis of quinolone resistance.

    Science.gov (United States)

    Aldred, Katie J; McPherson, Sylvia A; Turnbough, Charles L; Kerns, Robert J; Osheroff, Neil

    2013-04-01

    Although quinolones are the most commonly prescribed antibacterials, their use is threatened by an increasing prevalence of resistance. The most common causes of quinolone resistance are mutations of a specific serine or acidic residue in the A subunit of gyrase or topoisomerase IV. These amino acids are proposed to serve as a critical enzyme-quinolone interaction site by anchoring a water-metal ion bridge that coordinates drug binding. To probe the role of the proposed water-metal ion bridge, we characterized wild-type, GrlA(E85K), GrlA(S81F/E85K), GrlA(E85A), GrlA(S81F/E85A) and GrlA(S81F) Bacillus anthracis topoisomerase IV, their sensitivity to quinolones and related drugs and their use of metal ions. Mutations increased the Mg(2+) concentration required to produce maximal quinolone-induced DNA cleavage and restricted the divalent metal ions that could support quinolone activity. Individual mutation of Ser81 or Glu85 partially disrupted bridge function, whereas simultaneous mutation of both residues abrogated protein-quinolone interactions. Results provide functional evidence for the existence of the water-metal ion bridge, confirm that the serine and glutamic acid residues anchor the bridge, demonstrate that the bridge is the primary conduit for interactions between clinically relevant quinolones and topoisomerase IV and provide a likely mechanism for the most common causes of quinolone resistance.

  14. Widespread distribution of CTX-M and plasmid-mediated AmpC β-lactamases in Escherichia coli from Brazilian chicken meat

    Directory of Open Access Journals (Sweden)

    Larissa Alvarenga Batista Botelho

    2015-04-01

    Full Text Available The dissemination of plasmid-mediated antimicrobial resistance genes may pose a substantial public health risk. In the present work, the occurrences of blaCTX-M and plasmid-mediated ampC and qnr genes were investigated in Escherichia coli from 16 chicken carcasses produced by four commercial brands in Brazil. Of the brands tested, three were exporters, including one of organic chicken. Our study assessed 136 E. coli isolates that were grouped into 77 distinct biotypes defined by their origin, resistance profiling, the presence of β-lactamase and plasmid-mediated quinolone resistance genes and enterobacterial repetitive intergenic consensus-polimerase chain reaction typing. The blaCTX-M-15, blaCTX-M-2 and blaCTX-M-8 genes were detected in one, 17 and eight different biotypes, respectively (45 isolates. Twenty-one biotypes (46 isolates harboured blaCMY-2. Additionally, blaCMY-2 was identified in isolates that also carried either blaCTX-M-2 or blaCTX-M-8. The qnrB and/or qnrS genes occurred in isolates carrying each of the four types of β-lactamase determinants detected and also in oxyimino-cephalosporin-susceptible strains. Plasmid-mediated extended-spectrum β-lactamase (ESBL and AmpC determinants were identified in carcasses from the four brands tested. Notably, this is the first description of blaCTX-M-15 genes in meat or food-producing animals from South America. The blaCTX-M-8, blaCTX-M-15 and blaCMY-2 genes were transferable in conjugation experiments. The findings of the present study indicate that plasmid-mediated ESBL and AmpC-encoding genes are widely distributed in Brazilian chicken meat.

  15. Characterization of CTX-M enzymes, quinolone resistance determinants, and antimicrobial residues from hospital sewage, wastewater treatment plant, and river water.

    Science.gov (United States)

    Conte, Danieli; Palmeiro, Jussara Kasuko; da Silva Nogueira, Keite; de Lima, Thiago Marenda Rosa; Cardoso, Marco André; Pontarolo, Roberto; Degaut Pontes, Flávia Lada; Dalla-Costa, Libera Maria

    2017-02-01

    Multidrug-resistant (MDR) bacteria are widespread in hospitals and have been increasingly isolated from aquatic environments. The aim of the present study was to characterize extended-spectrum β-lactamase (ESBL) and quinolone-resistant Enterobacteriaceae from a hospital effluent, sanitary effluent, inflow sewage, aeration tank, and outflow sewage within a wastewater treatment plant (WWTP), as well as river water upstream and downstream (URW and DRW, respectively), of the point where the WWTP treated effluent was discharged. β-lactamase (bla) genes, plasmid-mediated quinolone resistance (PMQR), and quinolone resistance-determining regions (QRDRs) were assessed by amplification and sequencing in 55 ESBL-positive and/or quinolone-resistant isolates. Ciprofloxacin residue was evaluated by high performance liquid chromatography. ESBL-producing isolates were identified in both raw (n=29) and treated (n=26) water; they included Escherichia coli (32), Klebsiella pneumoniae (22) and Klebsiella oxytoca (1). Resistance to both cephalosporins and quinolone was observed in 34.4% of E. coli and 27.3% of K. pneumoniae. Resistance to carbapenems was found in 5.4% of K. pneumoniae and in K. oxytoca. Results indicate the presence of blaCTX-M (51/55, 92.7%) and blaSHV (8/55, 14.5%) ESBLs, and blaGES (2/55, 3.6%) carbapenemase-encoding resistance determinants. Genes conferring quinolone resistance were detected at all sites, except in the inflow sewage and aeration tanks. Quinolone resistance was primarily attributed to amino acid substitutions in the QRDR of GyrA (47%) or to the presence of PMQR (aac-(6')-Ib-cr, oqxAB, qnrS, and/or qnrB; 52.9%) determinants. Ciprofloxacin residue was absent only from URW. Our results have shown strains carrying ESBL genes, PMQR determinants, and mutations in the gyrA QRDR genes mainly in hospital effluent, URW, and DRW samples. Antimicrobial use, and the inefficient removal of MDR bacteria and antibiotic residue during sewage treatment, may

  16. Plasmid-mediated AmpC beta-lactamase-producing Escherichia coli causing urinary tract infection in the Auckland community likely to be resistant to commonly prescribed antimicrobials.

    Science.gov (United States)

    Drinkovic, Dragana; Morris, Arthur J; Dyet, Kristin; Bakker, Sarah; Heffernan, Helen

    2015-03-13

    To estimate the prevalence and characterise plasmid-mediated AmpC beta-lactamase (PMACBL)- producing Escherichia coli in the Auckland community. All cefoxitin non-susceptible (NS) E. coli identified at the two Auckland community laboratories between 1 January and 31 August 2011 were referred to ESR for boronic acid double-disc synergy testing, to detect the production of AmpC beta-lactamase, and polymerase chain reaction (PCR) to identify the presence of PMACBL genes. PMACBL-producing isolates were typed using pulsed-field gel electrophoresis (PFGE), and PCR was used to determine their phylogenetic group and to identify multilocus sequence type (ST)131. Antimicrobial susceptibility testing and detection of extended-spectrum beta-lactamases (ESBLs) were performed according to the Clinical and Laboratory Standards Institute recommendations. 101 (51%) and 74 (37%) of 200 non-duplicate cefoxitin-NS E. coli were PMACBL producers or assumed hyper-producers of chromosomal AmpC beta-lactamase, respectively. The prevalence of PMACBL-producing E. coli was 0.4%. PMACBL-producing E. coli were significantly less susceptible to norfloxacin, trimethoprim and nitrofurantoin than E. coli that produced neither a PMACBL nor an ESBL. Very few (4%) PMACBL-producing E. coli co-produced an ESBL. Most (88%) of the PMACBL-producing isolates had a CMY-2-like PMACBL. The PMACBL-producing E. coli isolates were diverse based on their PFGE profiles, 44% belonged to phylogenetic group D, and only four were ST131. 100 of the 101 PMACBL-producing E. coli were cultured from urine, and were causing urinary tract infection (UTI) in the majority of patients. The median patient age was 56 years and most (94%) of the patients were women. A greater proportion of patients with community-acquired UTI caused by PMACBL-producing E. coli received a beta-lactam antimicrobial than patients with community-acquired UTI caused by other non-AmpC, non-ESBL-producing E. coli. Thirty-six (43%) patients with community

  17. Prevalence of quinolone resistance mechanisms and associations to minimum inhibitory concentrations in quinolone-resistant Escherichia coli isolated from humans and swine in Denmark

    DEFF Research Database (Denmark)

    Cavaco, Lina; Frimodt-Møller, Niels; Hasman, Henrik;

    2008-01-01

    Prevalence of quinolone resistance mechanisms and associations to minimum inhibitory concentrations (MICs) of nalidixic acid (NAL) and ciprofloxacin (CIP) were investigated in 124 Escherichia coli isolated from humans (n = 85) and swine (n = 39) in Denmark. The collection included 59 high-level CIP......-resistant isolates (MIC >= 4) from human (n = 51) and pig origin (n = 8) and 65 low-level CIP-resistant isolates (MIC >= 0.125) from human (n = 34) and pig origin (n = 31). Resistance by target modification was screened by PCR amplification and sequencing, of the quinolone resistance determining regions (QRDRs......A and qnrS genes conferring quinolone resistance by target protection were detected in two human low-level CIP-resistant isolates that did not display NAL resistance. As expected, target mutation in QRDRs was the most prevalent mechanism of quinolone resistance. This mechanism was complemented by efflux...

  18. Substitutions of Ser83Leu in GyrA and Ser80Leu in ParC Associated with Quinolone Resistance in Acinetobacter pittii.

    Science.gov (United States)

    Gu, Dan-xia; Hu, Yun-jian; Zhou, Hong-wei; Zhang, Rong; Chen, Gong-xiang

    2015-06-01

    To investigate the prevalence and the mechanism of quinolone-resistant Acinetobacter pittii, 634 Acinetobacter calcoaceticus-Acinetobacter baumannii complex isolates were collected throughout Zhejiang Province. Identification of isolates was conducted by matrix-assisted laser desorption ionization/time of flight mass spectrometry (MALDI-TOF MS), blaOXA-51-like gene, and partial RNA polymerase β-subunit (rpoB) amplification. Twenty-seven isolates of A. pittii were identified. Among the 634 isolates, A. baumannii, A. pittii, Acinetobacter nosocomialis, and A. calcoaceticus counted for 87.22%, 4.26%, 8.20%, and 0.32%, respectively. Antimicrobial susceptibility of nalidixic acid, ofloxacin, enoxacin, ciprofloxacin, lomefloxacin, levofloxacin, sparfloxacin, moxifloxacin, and gatifloxacin for 27 A. pittii were determined by the agar dilution method. Detection of quinolone-resistant determining regions of gyrA, gyrB, parC, and parE was performed for the A. pittii isolates. In addition, plasmid-mediated quinolone resistance (PMQR) determinants (qnrA, qnrB, qnrS, qnrC, qnrD, aac(6')-Ib-cr, qepA, oqxA, and oqxB) were investigated. All the 27 isolates demonstrated a higher minimum inhibitory concentration (MIC) to old quinolones than the new fluoroquinolones. No mutation in gyrA, gyrB, parC, or parE was detected in 20 ciprofloxacin-susceptible isolates. Seven ciprofloxacin-resistant A. pittii were identified with a Ser83Leu mutation in GyrA. Among them, six isolates with simultaneous Ser83Leu amino acid substitution in GyrA and Ser80Leu in ParC displayed higher MIC values against ciprofloxacin. Additionally, three were identified with a Met370Ile substitution in ParE, and two were detected with a Tyr317His mutation in ParE, which were reported for the first time. No PMQR determinants were identified in the 27 A. pittii isolates. In conclusion, mutations in chromosome play a major role in quinolone resistance in A. pittii, while resistance mechanisms mediated by plasmid have

  19. Drug interactions with Bacillus anthracis topoisomerase IV: biochemical basis for quinolone action and resistance.

    Science.gov (United States)

    Aldred, Katie J; McPherson, Sylvia A; Wang, Pengfei; Kerns, Robert J; Graves, David E; Turnbough, Charles L; Osheroff, Neil

    2012-01-10

    Bacillus anthracis, the causative agent of anthrax, is considered a serious threat as a bioweapon. The drugs most commonly used to treat anthrax are quinolones, which act by increasing the levels of DNA cleavage mediated by topoisomerase IV and gyrase. Quinolone resistance most often is associated with specific serine mutations in these enzymes. Therefore, to determine the basis for quinolone action and resistance, we characterized wild-type B. anthracis topoisomerase IV, the GrlA(S81F) and GrlA(S81Y) quinolone-resistant mutants, and the effects of quinolones and a related quinazolinedione on these enzymes. Ser81 is believed to anchor a water-Mg(2+) bridge that coordinates quinolones to the enzyme through the C3/C4 keto acid. Consistent with this hypothesized bridge, ciprofloxacin required increased Mg(2+) concentrations to support DNA cleavage by GrlA(S81F) topoisomerase IV. The three enzymes displayed similar catalytic activities in the absence of drugs. However, the resistance mutations decreased the affinity of topoisomerase IV for ciprofloxacin and other quinolones, diminished quinolone-induced inhibition of DNA religation, and reduced the stability of the enzyme-quinolone-DNA ternary complex. Wild-type DNA cleavage levels were generated by mutant enzymes at high quinolone concentrations, suggesting that increased drug potency could overcome resistance. 8-Methyl-quinazoline-2,4-dione, which lacks the quinolone keto acid (and presumably does not require the water-Mg(2+) bridge to mediate protein interactions), was more potent than quinolones against wild-type topoisomerase IV and was equally efficacious. Moreover, it maintained high potency and efficacy against the mutant enzymes, effectively inhibited DNA religation, and formed stable ternary complexes. Our findings provide an underlying biochemical basis for the ability of quinazolinediones to overcome clinically relevant quinolone resistance mutations in bacterial type II topoisomerases.

  20. Plasmid-Mediated Sulfamethoxazole Resistance Encoded by the sul2 Gene in the Multidrug-Resistant Shigella flexneri 2a Isolated from Patients with Acute Diarrhea in Dhaka, Bangladesh

    Science.gov (United States)

    Iqbal, Mohd S.; Rahman, Mostafizur; Islam, Rafiad; Banik, Atanu; Amin, M. Badrul; Akter, Fatema; Talukder, Kaisar Ali

    2014-01-01

    In this study, mechanisms of plasmid-mediated sulfamethoxazole resistances in the clinical strains of multi-drug resistant (MDR) Shigella flexneri 2a were elucidated for the first time in Bangladesh. From 2006 to 2011, a total of 200 S. flexneri 2a strains were randomly selected from the stock of the Enteric and Food Microbiology Laboratory of icddr,b. Antimicrobial susceptibility of the strains showed 73%, 98%, 93%, 58%, 98%, 64% and 4% resistance to trimethoprim-sulfamethoxazole, nalidixic acid, ampicillin, erythromycin, tetracycline, ciprofloxacin and ceftriaxone respectively. Plasmid profiling revealed heterogeneous patterns and interestingly, all the trimethoprim-sulfamethoxazole resistant (SXTR) strains yielded a distinct 4.3 MDa plasmid compared to that of the trimethoprim-sulfamethoxazole susceptible (SXTS) strains. Curing of this 4.3 MDa plasmid resulted in the susceptibility to sulfamethoxazole alone suggesting the involvement of this plasmid in the resistance of sulfamethoxazole. Moreover, PCR analysis showed the presence of sul2 gene in SXTR strains which is absent in SXTS strains as well as in the 4.3 MDa plasmid-cured derivatives, confirming the involvement of sul2 in the resistance of sulfamethoxazole. Furthermore, pulsed-field gel electrophoresis (PFGE) analysis revealed that both the SXTR and SXTS strains were clonal. This study will significantly contributes to the knowledge on acquired drug resistance of the mostly prevalent S. flexneri 2a and further warrants continuous monitoring of the prevalence and correlation of this resistance determinants amongst the clinical isolates of Shigella and other enteric pathogens around the world to provide effective clinical management of the disease. PMID:24416393

  1. Plasmid-mediated sulfamethoxazole resistance encoded by the sul2 gene in the multidrug-resistant Shigella flexneri 2a isolated from patients with acute diarrhea in Dhaka, Bangladesh.

    Directory of Open Access Journals (Sweden)

    Mohd S Iqbal

    Full Text Available In this study, mechanisms of plasmid-mediated sulfamethoxazole resistances in the clinical strains of multi-drug resistant (MDR Shigella flexneri 2a were elucidated for the first time in Bangladesh. From 2006 to 2011, a total of 200 S. flexneri 2a strains were randomly selected from the stock of the Enteric and Food Microbiology Laboratory of icddr,b. Antimicrobial susceptibility of the strains showed 73%, 98%, 93%, 58%, 98%, 64% and 4% resistance to trimethoprim-sulfamethoxazole, nalidixic acid, ampicillin, erythromycin, tetracycline, ciprofloxacin and ceftriaxone respectively. Plasmid profiling revealed heterogeneous patterns and interestingly, all the trimethoprim-sulfamethoxazole resistant (SXT(R strains yielded a distinct 4.3 MDa plasmid compared to that of the trimethoprim-sulfamethoxazole susceptible (SXT(S strains. Curing of this 4.3 MDa plasmid resulted in the susceptibility to sulfamethoxazole alone suggesting the involvement of this plasmid in the resistance of sulfamethoxazole. Moreover, PCR analysis showed the presence of sul2 gene in SXT(R strains which is absent in SXT(S strains as well as in the 4.3 MDa plasmid-cured derivatives, confirming the involvement of sul2 in the resistance of sulfamethoxazole. Furthermore, pulsed-field gel electrophoresis (PFGE analysis revealed that both the SXT(R and SXT(S strains were clonal. This study will significantly contributes to the knowledge on acquired drug resistance of the mostly prevalent S. flexneri 2a and further warrants continuous monitoring of the prevalence and correlation of this resistance determinants amongst the clinical isolates of Shigella and other enteric pathogens around the world to provide effective clinical management of the disease.

  2. Emergence of plasmid-mediated colistin resistance and New Delhi metallo-β-lactamase genes in extensively drug-resistant Escherichia coli isolated from a patient in Thailand.

    Science.gov (United States)

    Paveenkittiporn, Wantana; Kerdsin, Anusak; Chokngam, Sukanya; Bunthi, Charatdao; Sangkitporn, Somchai; Gregory, Christopher J

    2017-02-01

    We reported a case of Escherichia coli with colistin resistance and an extensively drug-resistant phenotype. Molecular analysis revealed that the isolate carried mcr-1 and multiple β-lactamase genes includingblaNDM1, blaCTX-M-15, blaTEM1, and blaCMY-2. This is the first report of a clinical mcr-1 isolate in Thailand highlighting the urgent need for a comprehensive antimicrobial resistance containment strategy to prevent further spread.

  3. Differentiation in quinolone resistance by virulence genotype in Pseudomonas aeruginosa.

    Directory of Open Access Journals (Sweden)

    Melissa Agnello

    Full Text Available Pseudomonas aeruginosa is a leading pathogen that has become increasingly resistant to the fluoroquinolone antibiotics due to widespread prescribing. Adverse outcomes have been shown for patients infected with fluoroquinolone-resistant strains. The type III secretion system (TTSS is a major virulence determinant during acute infections through the injection of effector toxins into host cells. Most strains exhibit a unique TTSS virulence genotype defined by the presence of either exoS or exoU gene encoding two of the effector toxins, ExoS and ExoU, respectively. Specific TTSS effector genotype has been shown previously to differentially impact virulence in pneumonia. In this study, we examined the relationship between TTSS effector genotype and fluoroquinolone resistance mechanisms in a collection of 270 respiratory isolates. We found that a higher proportion of exoU+ strains were fluoroquinolone-resistant compared to exoS+ strains (63% vs 49%, p = 0.03 despite its lower overall prevalence (38% exoU+ vs 56% exoS+. Results from sequencing the quinolone resistance determining regions (QRDRs of the 4 target genes (gyrA, gyrB, parC, parE indicated that strains containing the exoU gene were more likely to acquire ≥ 2 mutations than exoS+ strains at MICs ≤ 8 µg/ml (13% vs none and twice as likely to have mutations in both gyrA and parC than exoS+ strains (48% vs 24% p = 0.0439. Our findings indicate that P. aeruginosa strains differentially develop resistance-conferring mutations that correlate with TTSS effector genotype and the more virulent exoU+ subpopulation. Differences in mutational processes by virulence genotype that were observed suggest co-evolution of resistance and virulence traits favoring a more virulent genotype in the quinolone-rich clinical environment.

  4. Contribution of topoisomerase IV mutation to quinolone resistance in Mycoplasma genitalium.

    Science.gov (United States)

    Yamaguchi, Yuko; Takei, Masaya; Kishii, Ryuta; Yasuda, Mitsuru; Deguchi, Takashi

    2013-04-01

    The mechanism of quinolone resistance in Mycoplasma genitalium remains poorly understood due to difficulties with in vitro culture, especially of clinical isolates. In this study, to confirm the association between mutations in topoisomerases and antimicrobial susceptibilities to quinolones, ciprofloxacin-resistant mutant strains were selected using the cultivable type strain ATCC 33530. Sequence analysis revealed that the mutant strains harbored mutations in topoisomerase IV: Gly81Cys in ParC, Pro261Thr in ParC, or Asn466Lys in ParE. The MICs of all quinolones tested against the mutant strains were 2- to 16-fold higher than those against the wild-type strain. No cross-resistance was observed with macrolides or tetracyclines. We determined the inhibitory activities of quinolones against DNA gyrase and topoisomerase IV in order to investigate the correlation between antimicrobial susceptibility and inhibitory activity against the target enzymes, considered the primary targets of quinolones. Furthermore, using enzymatic analysis, we confirmed that Gly81Cys in the ParC quinolone resistance-determining region (QRDR) contributed to quinolone resistance. This is the first study to isolate quinolone-resistant mutant strains of M. genitalium harboring substitutions in the parC or parE gene in vitro and to measure the inhibitory activities against the purified topoisomerases of M. genitalium.

  5. Sub-inhibitory concentrations of vancomycin prevent quinolone-resistance in a penicillin-resistant isolate of Streptococcus pneumoniae

    Directory of Open Access Journals (Sweden)

    Moreillon Philippe

    2001-07-01

    Full Text Available Abstract Background The continuous spread of penicillin-resistant pneumococci represents a permanent threat in the treatment of pneumococcal infections, especially when strains show additional resistance to quinolones. The main objective of this study was to determine a treatment modality impeding the emergence of quinolone resistance. Results Exposure of a penicillin-resistant pneumococcus to increasing concentrations of trovafloxacin or ciprofloxacin selected for mutants resistant to these drugs. In the presence of sub-inhibitory concentrations of vancomycin, development of trovafloxacin-resistance and high-level ciprofloxacin-resistance were prevented. Conclusions Considering the risk of quinolone-resistance in pneumococci, the observation might be of clinical importance.

  6. Impact of mutations in DNA gyrase genes on quinolone resistance in Campylobacter jejuni.

    Science.gov (United States)

    Changkwanyeun, Ruchirada; Yamaguchi, Tomoyuki; Kongsoi, Siriporn; Changkaew, Kanjana; Yokoyama, Kazumasa; Kim, Hyun; Suthienkul, Orasa; Usui, Masaru; Tamura, Yutaka; Nakajima, Chie; Suzuki, Yasuhiko

    2016-10-01

    Amino acid substitutions providing quinolone resistance to Campyloabcter jejuni have been found in the quinolone resistance-determining region of protein DNA gyrase subunit A (GyrA), with the highest frequency at position 86 followed by position 90. In this study, wild-type and mutant recombinant DNA gyrase subunits were expressed in Escherichia coli and purified using Ni-NTA agarose column chromatography. Soluble 97 kDa GyrA and 87 kDa DNA gyrase subunit B were shown to reconstitute ATP-dependent DNA supercoiling activity. A quinolone-inhibited supercoiling assay demonstrated the roles of Thr86Ile, Thr86Ala, Thr86Lys, Asp90Asn, and Asp90Tyr amino acid substitutions in reducing sensitivity to quinolones. The marked effect of Thr86Ile on all examined quinolones suggested the advantage of this substitution in concordance with recurring isolation of quinolone-resistant C. jejuni. An analysis of the structure-activity relationship showed the importance of the substituent at position 8 in quinolones to overcome the effect of Thr86Ile. Sitafloxacin (SIT), which has a fluorinate cyclopropyl ring at R-1 and a chloride substituent at R-8, a characteristic not found in other quinolones, showed the highest inhibitory activity against all mutant C. jejuni gyrases including ciprofloxacin-resistant mutants. The results suggest SIT as a promising drug for the treatment of campylobacteriosis caused by CIP-resistant C. jejuni. Copyright © 2016 John Wiley & Sons, Ltd.

  7. Antibiotic-Resistant Extended Spectrum ß-Lactamase- and Plasmid-Mediated AmpC-Producing Enterobacteriaceae Isolated from Retail Food Products and the Pearl River in Guangzhou, China

    Science.gov (United States)

    Ye, Qinghua; Wu, Qingping; Zhang, Shuhong; Zhang, Jumei; Yang, Guangzhu; Wang, Huixian; Huang, Jiahui; Chen, Mongtong; Xue, Liang; Wang, Juan

    2017-01-01

    We conducted a survey in 2015 to evaluate the presence of extended spectrum β-lactamase (ESBL)- and plasmid-mediated AmpC-producing Enterobacteriaceae in retail food and water of the Pearl River in Guangzhou, China, as well as their antibiotic resistance profiles. Samples (88 fresh food samples and 43 water samples) from eight different districts were analyzed by direct plating and after enrichment. Multidrug-resistant strains were found in 41.7 and 43.4% of food and water samples, respectively. ESBLs were found in 3.4 and 11.6% of food and water samples, respectively, and AmpC producers were found in 13.6 and 16.3% of food and water samples, respectively. Molecular characterization revealed the domination of blaCTX−Mgenes; plasmidic AmpC was of the type DHA-1 both in food and water samples. Thirteen of Fifty one β-lactamase-producing positive isolates were detected to be transconjugants, which readily received the β-lactamase genes conferring resistance to β-lactam antibiotics as well as some non-β-lactam antibiotics. These findings provide evidence that retail food and the river water may be considered as reservoirs for the dissemination of β-lactam antibiotics, and these resistance genes could readily be transmitted to humans through the food chain and water. PMID:28217112

  8. Dynamics of Quinolone Resistance in Fecal Escherichia coli of Finishing Pigs after Ciprofloxacin Administration

    OpenAIRE

    Huang, Kang; Xu, Chang-Wen; Zeng, Bo; XIA, Qing-Qing; Zhang, An-Yun; LEI, Chang-Wei; Guan, Zhong-Bin; Cheng, Han; Wang, Hong-ning

    2014-01-01

    ABSTRACT Escherichia coli resistance to quinolones has now become a serious issue in large-scale pig farms of China. It is necessary to study the dynamics of quinolone resistance in fecal Escherichia coli of pigs after antimicrobial administration. Here, we present the hypothesis that the emergence of resistance in pigs requires drug accumulation for 7 days or more. To test this hypothesis, 26 pigs (90 days old, about 30 kg) not fed any antimicrobial after weaning were selected and divided in...

  9. Accumulation of plasmid-mediated fluoroquinolone resistance genes, qepA and qnrS1, in Enterobacter aerogenes co-producing RmtB and class A beta-lactamase LAP-1.

    Science.gov (United States)

    Park, Yeon-Joon; Yu, Jin Kyung; Kim, Sang-Il; Lee, Kyungwon; Arakawa, Yoshichika

    2009-01-01

    A new plasmid-mediated fluoroquinolone efflux pump gene, qepA, is known to be associated with the rmtB gene, which confers high-level resistance to aminoglycosides. We investigated the qepA gene in 573 AmpC-producing Enterobacteriaceae including one Citrobacter freundii known to harbor rmtB. Of them, two clonally unrelated E. aerogenes harbored qepA. Both isolates co-harbored rmtB, qnrS1, qepA, and bla(LAP-1) on an IncFI type plasmid. The qepA was flanked by two copies of IS26 containing ISCR3C, tnpA, tnpR, bla(TEM), and rmtB. The qnrS1 and bla(LAP-1) were located upstream of qepA. All the resistance determinants (qepA, qnrS1, rmtB, and bla(LAP-1)) were co-transferred to E. coli J53 by filter mating from both isolates. Although the prevalence of qepA is currently low, considering the presence of ISCR3C and the possibility of co-selection and co-transferability of plasmids, more active surveillance for these multi-drug resistant bacteria and prudent use of antimicrobials are needed.

  10. 质粒介导的喹诺酮类药物耐药研究进展%Plasmid-mediated quinolone resistance

    Institute of Scientific and Technical Information of China (English)

    宁永忠; 王辉; 张捷

    2007-01-01

    喹诺酮类药物(Quinolones)是一类广谱、强效的化学合成抗细菌药物。长期以来,细菌通过染色体介导的靶位点改变、蓄积减少(包括孔蛋白缺失、主动外排增加)等机制逐渐对其形成耐药。尽管有报道发现有喹诺酮类耐药基因在移动片段上并可通过转化完成水平基因转移,但质粒介导耐药仍十分罕见。

  11. Characteristics of Quinolone Resistance in Escherichia coli Isolates from Humans, Animals, and the Environment in the Czech Republic

    Science.gov (United States)

    Röderova, Magdalena; Halova, Dana; Papousek, Ivo; Dolejska, Monika; Masarikova, Martina; Hanulik, Vojtech; Pudova, Vendula; Broz, Petr; Htoutou-Sedlakova, Miroslava; Sauer, Pavel; Bardon, Jan; Cizek, Alois; Kolar, Milan; Literak, Ivan

    2017-01-01

    Escherichia coli is a common commensal bacterial species of humans and animals that may become a troublesome pathogen causing serious diseases. The aim of this study was to characterize the quinolone resistance phenotypes and genotypes in E. coli isolates of different origin from one area of the Czech Republic. E. coli isolates were obtained from hospitalized patients and outpatients, chicken farms, retailed turkeys, rooks wintering in the area, and wastewaters. Susceptibility of the isolates grown on the MacConkey agar with ciprofloxacin (0.05 mg/L) to 23 antimicrobial agents was determined. The presence of plasmid-mediated quinolone resistance (PMQR) and ESBL genes was tested by PCR and sequencing. Specific mutations in gyrA, gyrB, parC, and parE were also examined. Multilocus sequence typing and pulsed-field gel electrophoresis were performed to assess the clonal relationship. In total, 1050 E. coli isolates were obtained, including 303 isolates from humans, 156 from chickens, 105 from turkeys, 114 from the rooks, and 372 from wastewater samples. PMQR genes were detected in 262 (25%) isolates. The highest occurrence was observed in isolates from retailed turkey (49% of the isolates were positive) and inpatients (32%). The qnrS1 gene was the most common PMQR determinant identified in 146 (56%) followed by aac(6′)-Ib-cr in 77 (29%), qnrB19 in 41 (16%), and qnrB1 in 9 (3%) isolates. All isolates with high level of ciprofloxacin resistance (>32 mg/L) carried double or triple mutations in gyrA combined with single or double mutations in parC. The most frequently identified substitutions were Ser(83)Leu; Asp(87)Asn in GyrA, together with Ser(80)Ile, or Glu(84)Val in ParC. Majority of these isolates showed resistance to beta-lactams and multiresistance phenotype was found in 95% isolates. Forty-eight different sequence types among 144 isolates analyzed were found, including five major clones ST131 (26), ST355 (19), ST48 (13), ST95 (10), and ST10 (5). No isolates

  12. Study on drug resistance and plasmid-mediated resistance mechanisms of ciprofloxacin-resistant Pseudomonas aeruginosa%铜绿假单胞菌耐药性及质粒介导的耐环丙沙星分子机制研究

    Institute of Scientific and Technical Information of China (English)

    陈茶; 黄彬; 陈利达; 吴强贵; 陈树林; 李有强; 林冬玲; 张妮

    2012-01-01

    OBJECTIVE To study the drug resistance and detect plasmid-mediated ciprofloxacin-resistant genes in clinical isolates of Pseudomonas aeruginosa , and study the molecular resistant mechanisms. METHODS The clinical isolates were identified by the automatic VITEK 2 system and the antimicrobial susceptibility was tested by K-B disc diffusion. The quinolone-resistant genes mediated by plasmids including qnrA, qnrB, qnrC, qnrD, qnrS, qepA and aac(6')-Ibcr were analyzed by polymerase chain reaction. RESULTS The resistance rates of 423 isolates of P. aeruginosa to ciprofloxacin and levofloxacin were 23. 2%, the resistance rates to the first and third generation of cephalosporins were higher than 49. 2% except 22. 7% to ceftazidime, the resistance rates to aminoglycoside antibiotics such as gentamicin, tobramycin, and amikacin were 17. 5%, 17. 5% and 13. 0%, respectively; the drug resistance rates to penicillins were higher than 40. 4% except 26. 2% to piperacillin, there was large difference in the resistant rate to β-lactamase inhibitor combinations, piperacillin/tazobactam (17. 0%) and ampicillin/sulbactam (98. 6%); the resistance rates to imipenem and meropenem were 24. 6% and 26. 0%, respectively; of 127 strains of ciprofloxacin-resistant P. aeruginosa isolates, the drug resistance increased significantly, the resistance rate to levofloxacin was 86. 6%, the resistance rate to the third generation of cephalosporin rose above 61. 4% , the resistance rate to the fourth generation of cephalosporin cefepime rose from 20.3% to 62. 2%; the resistance rate to β-lactamase inhibitor complexes increased from 17. 0% to 49. 6% or above, and the resistance rates to aminoglycosides (gentamicin, tobramycin) rose to 64. 6% or above, the resistance rate to amikacin increased from 13. 0% to 48. 8% ; there were no qnrS and qnrC that were detected in ciprofloxacin-resistant P. aeruginosa, the positive rates of qnrA, qnrB, qnrD, qepA and aac(6')-Ib-cr gene were 31. 2% , 87. 5% , 15. 6

  13. An outbreak of multidrug-resistant, quinolone-resistant Salmonella enterica serotype typhimurium DT104

    DEFF Research Database (Denmark)

    Molbak, K.; Baggesen, Dorte Lau; Aarestrup, Frank Møller

    1999-01-01

    , and tetracycline. An increasing proportion of DT104 isolates also have reduced susceptibility to fluoroquinolones. Methods The Danish salmonella surveillance program determines the phage types of all typhimurium strains from the food chain, and in the case of suspected outbreaks, five-drug-resistant strains...... findings here. Results Until 1997, DT104 infections made up less than 1 percent of all human salmonella infections. The strain isolated from patients in the first community outbreak of DT104 in Denmark, in 1998, was resistant to nalidixic acid and had reduced susceptibility to fluoroquinolones...... with fluoroquinolones. Conclusions Our investigation of an outbreak of DT104 documented the spread of quinolone-resistant bacteria from food animals to humans; this spread was associated with infections that were difficult to treat. Because of the increase in quinolone resistance in salmonella, the use...

  14. Interplay between intrinsic and acquired resistance to quinolones in Stenotrophomonas maltophilia.

    Science.gov (United States)

    García-León, Guillermo; Salgado, Fabiola; Oliveros, Juan Carlos; Sánchez, María Blanca; Martínez, José Luis

    2014-05-01

    To analyse whether the mutation-driven resistance-acquisition potential of a given bacterium might be a function of its intrinsic resistome, quinolones were used as selective agents and Stenotrophomonas maltophilia was chosen as a bacterial model. S. maltophilia has two elements - SmQnr and SmeDEF - that are important in intrinsic resistance to quinolones. Using a battery of mutants in which either or both of these elements had been removed, the apparent mutation frequency for quinolone resistance and the phenotype of the selected mutants were found to be related to the intrinsic resistome and also depended on the concentration of the selector. Most mutants had phenotypes compatible with the overexpression of multidrug efflux pump(s); SmeDEF overexpression was the most common cause of quinolone resistance. Whole genome sequencing showed that mutations of the SmeRv regulator, which result in the overexpression of the efflux pump SmeVWX, are the cause of quinolone resistance in mutants not overexpressing SmeDEF. These results indicate that the development of mutation-driven antibiotic resistance is highly dependent on the intrinsic resistome, which, at least for synthetic antibiotics such as quinolones, did not develop as a response to the presence of antibiotics in the natural ecosystems in which S. maltophilia evolved.

  15. Structural insights into the quinolone resistance mechanism of Mycobacterium tuberculosis DNA gyrase.

    Directory of Open Access Journals (Sweden)

    Jérémie Piton

    Full Text Available Mycobacterium tuberculosis DNA gyrase, an indispensable nanomachine involved in the regulation of DNA topology, is the only type II topoisomerase present in this organism and is hence the sole target for quinolone action, a crucial drug active against multidrug-resistant tuberculosis. To understand at an atomic level the quinolone resistance mechanism, which emerges in extensively drug resistant tuberculosis, we performed combined functional, biophysical and structural studies of the two individual domains constituting the catalytic DNA gyrase reaction core, namely the Toprim and the breakage-reunion domains. This allowed us to produce a model of the catalytic reaction core in complex with DNA and a quinolone molecule, identifying original mechanistic properties of quinolone binding and clarifying the relationships between amino acid mutations and resistance phenotype of M. tuberculosis DNA gyrase. These results are compatible with our previous studies on quinolone resistance. Interestingly, the structure of the entire breakage-reunion domain revealed a new interaction, in which the Quinolone-Binding Pocket (QBP is blocked by the N-terminal helix of a symmetry-related molecule. This interaction provides useful starting points for designing peptide based inhibitors that target DNA gyrase to prevent its binding to DNA.

  16. Characterization of ESBLs and associated quinolone resistance in Escherichia coli and Klebsiella pneumoniae isolates from an urban wastewater treatment plant in Algeria.

    Science.gov (United States)

    Alouache, Souhila; Estepa, Vanesa; Messai, Yamina; Ruiz, Elena; Torres, Carmen; Bakour, Rabah

    2014-02-01

    The aim of the study was the characterization of extended spectrum beta-lactamases (ESBLs) and quinolone resistance in cefotaxime-resistant coliform isolates from a wastewater treatment plant (WWTP). ESBLs were detected in 19 out of 24 isolates (79%) from raw water and in 21 out of 24 isolates (87.5%) from treated water, identified as Klebsiella pneumoniae and Escherichia coli. Molecular characterization of ESBLs and quinolone resistance showed allele profiles CTX-M-15 (3), CTX-M-3 (5), CTX-M-15+qnrB1 (1), CTX-M-3+qnrB1 (1), CTX-M-15+aac-(6')-Ib-cr (4), and CTX-M-15+qnrB1+aac-(6')-Ib-cr (7). A double mutation S83L and D87N (GyrA) and a single mutation S80I (ParC) were detected in ciprofloxacin-resistant E. coli isolates. In K. pneumoniae, mutations S83I (GyrA)+S80I (ParC) or single S80I mutation were detected in ciprofloxacin-resistant isolates, and no mutation was observed in ciprofloxacin-susceptible isolates. bla(CTX-M), qnrB1, and aac-(6')-Ib-cr were found, respectively, in these genetic environments: ISEcp1-bla(CTX-M)-orf477, orf1005-orf1-qnrB1, and Tn1721-IS26-aac-(6')-Ib-cr-bla(OXA-1)-catB4. bla(CTX-M-15) was located on IncF plasmid in E. coli and bla(CTX-M-3) on IncL/M plasmid in both species (E. coli and K. pneumoniae). E. coli isolates were affiliated to the phylogroups/MLST: D/ST405 (CC405), A/ST10 (CC10), A/ST617 (CC10), and B1/ST1431. K. pneumoniae isolates belonged to phylogroup KpI and to sequence types ST15, ST17, ST36, ST48, ST54, and ST147. The study showed a multi-drug resistance at the inflow and outflow of the WWTP, with ESBL production, plasmid-mediated quinolones resistance, and mutations in topoisomerases. The findings highlight the similarity of antibiotic resistance mechanisms in the clinical setting and the environment, and the role of the latter as a source of dissemination of resistance genes.

  17. Quinolone resistance in absence of selective pressure: the experience of a very remote community in the Amazon forest.

    Directory of Open Access Journals (Sweden)

    Lucia Pallecchi

    Full Text Available BACKGROUND: Quinolones are potent broad-spectrum bactericidal agents increasingly employed also in resource-limited countries. Resistance to quinolones is an increasing problem, known to be strongly associated with quinolone exposure. We report on the emergence of quinolone resistance in a very remote community in the Amazon forest, where quinolones have never been used and quinolone resistance was absent in 2002. METHODS: The community exhibited a considerable level of geographical isolation, limited contact with the exterior and minimal antibiotic use (not including quinolones. In December 2009, fecal carriage of antibiotic resistant Escherichia coli was investigated in 120 of the 140 inhabitants, and in 48 animals reared in the community. All fluoroquinolone-resistant isolates were genotyped and characterized for the mechanisms of plasmid- and chromosomal-mediated quinolone resistance. PRINCIPAL FINDINGS: Despite the characteristics of the community remained substantially unchanged during the period 2002-2009, carriage of quinolone-resistant E. coli was found to be common in 2009 both in humans (45% nalidixic acid, 14% ciprofloxacin and animals (54% nalidixic acid, 23% ciprofloxacin. Ciprofloxacin-resistant isolates of human and animal origin showed multidrug resistance phenotypes, a high level of genetic heterogeneity, and a combination of GyrA (Ser83Leu and Asp87Asn and ParC (Ser80Ile substitutions commonly observed in fluoroquinolone-resistant clinical isolates of E. coli. CONCLUSIONS: Remoteness and absence of antibiotic selective pressure did not protect the community from the remarkable emergence of quinolone resistance in E. coli. Introduction of the resistant strains from antibiotic-exposed settings is the most likely source, while persistence and dissemination in the absence of quinolone exposure is likely mostly related with poor sanitation. Interventions aimed at reducing the spreading of resistant isolates (by improving sanitation

  18. The Impact of Antibiotic Stewardship Programs in Combating Quinolone Resistance: A Systematic Review and Recommendations for More Efficient Interventions.

    Science.gov (United States)

    Pitiriga, Vasiliki; Vrioni, Georgia; Saroglou, George; Tsakris, Athanasios

    2017-04-01

    Quinolones are among the most commonly prescribed antibiotics worldwide. A clear relationship has been demonstrated between excessive quinolone use and the steady increase in the incidence of quinolone-resistant bacterial pathogens, both in hospital and community sites. In addition, exposure to quinolones has been associated with colonization and infection with healthcare-associated pathogens such as methicillin-resistant Staphylococcus aureus and Clostridium difficile in hospitalized patients. Therefore, the management of quinolone prescribing in hospitals through antibiotic stewardship programs is considered crucial. Although suggestions have been made by previous studies on the positive impact of stewardship programs concerning the emergence and spread of multidrug-resistant bacteria at hospital level, the association of quinolone-targeted interventions with reduction of quinolone resistance is vague. The purpose of this article was to evaluate the impact of stewardship interventions on quinolone resistance rates and healthcare-associated infections, through a literature review using systematic methods to identify and select the appropriate studies. Recommendations for improvements in quinolone-targeted stewardship programs are also proposed. Efforts in battling quinolone resistance should combine various interventions such as restriction formulary policies, prospective audits with feedback to prescribers, infection prevention and control measures, prompt detection of low-level resistance, educational programs, and guidelines for optimal quinolone usage. However, the effectiveness of such strategies should be assessed by properly designed and conducted clinical trials. Finally, novel approaches in diagnostic stewardship for rapidly detecting bacterial resistance, including PCR-based techniques, mass spectrometry, microarrays, and whole-genome sequencing as well as the prompt investigation on the clonality of quinolone-resistant strains, will strengthen our

  19. Prevalence of quinolone resistance mechanisms and associations to minimum inhibitory concentrations in quinolone-resistant Escherichia coli isolated from humans and swine in Denmark.

    Science.gov (United States)

    Cavaco, Lina Maria; Frimodt-Møller, Niels; Hasman, Henrik; Guardabassi, Luca; Nielsen, Lene; Aarestrup, Frank Møller

    2008-06-01

    Prevalence of quinolone resistance mechanisms and associations to minimum inhibitory concentrations (MICs) of nalidixic acid (NAL) and ciprofloxacin (CIP) were investigated in 124 Escherichia coli isolated from humans (n=85) and swine (n=39) in Denmark. The collection included 59 high-level CIP-resistant isolates (MIC >or= 4) from human (n=51) and pig origin (n=8) and 65 low-level CIP-resistant isolates (MIC >or= 0.125) from human (n=34) and pig origin (n=31). Resistance by target modification was screened by PCR amplification and sequencing of the quinolone resistance determining regions (QRDRs) of gyrA, gyrB, parC, and parE. QRDR mutations occurred in all except two isolates (98%). All high-level CIP-resistant E. coli had one or two mutations in gyrA in combination with mutations in parC or parE. Mutations in parC and parE were only found in combination with gyrA mutations, and no mutations were observed in gyrB. Efflux pump mechanisms were detected in 10 human (11.8%) and 29 porcine (74.4%) isolates by an efflux pump inhibitor (EPI) agar dilution assay. The aac(6')-Ib-cr gene mediating resistance by enzymatic modification was found in 12 high-level CIP-resistant human isolates. The qnrA and qnrS genes conferring quinolone resistance by target protection were detected in two human low-level CIP-resistant isolates that did not display NAL resistance. As expected, target mutation in QRDRs was the most prevalent mechanism of quinolone resistance. This mechanism was complemented by efflux mechanisms in most porcine isolates. Transferable resistance by target protection or enzymatic modification was less common (10%) and restricted to human isolates.

  20. Antimalarial therapy selection for quinolone resistance among Escherichia coli in the absence of quinolone exposure, in tropical South America.

    Directory of Open Access Journals (Sweden)

    Ross J Davidson

    Full Text Available BACKGROUND: Bacterial resistance to antibiotics is thought to develop only in the presence of antibiotic pressure. Here we show evidence to suggest that fluoroquinolone resistance in Escherichia coli has developed in the absence of fluoroquinolone use. METHODS: Over 4 years, outreach clinic attendees in one moderately remote and five very remote villages in rural Guyana were surveyed for the presence of rectal carriage of ciprofloxacin-resistant gram-negative bacilli (GNB. Drinking water was tested for the presence of resistant GNB by culture, and the presence of antibacterial agents and chloroquine by HPLC. The development of ciprofloxacin resistance in E. coli was examined after serial exposure to chloroquine. Patient and laboratory isolates of E. coli resistant to ciprofloxacin were assessed by PCR-sequencing for quinolone-resistance-determining-region (QRDR mutations. RESULTS: In the very remote villages, 4.8% of patients carried ciprofloxacin-resistant E. coli with QRDR mutations despite no local availability of quinolones. However, there had been extensive local use of chloroquine, with higher prevalence of resistance seen in the villages shortly after a Plasmodium vivax epidemic (p<0.01. Antibacterial agents were not found in the drinking water, but chloroquine was demonstrated to be present. Chloroquine was found to inhibit the growth of E. coli in vitro. Replica plating demonstrated that 2-step QRDR mutations could be induced in E. coli in response to chloroquine. CONCLUSIONS: In these remote communities, the heavy use of chloroquine to treat malaria likely selected for ciprofloxacin resistance in E. coli. This may be an important public health problem in malarious areas.

  1. Overcoming target-mediated quinolone resistance in topoisomerase IV by introducing metal-ion-independent drug-enzyme interactions.

    Science.gov (United States)

    Aldred, Katie J; Schwanz, Heidi A; Li, Gangqin; McPherson, Sylvia A; Turnbough, Charles L; Kerns, Robert J; Osheroff, Neil

    2013-12-20

    Quinolones, which target gyrase and topoisomerase IV, are the most widely prescribed antibacterials worldwide. Unfortunately, their use is threatened by the increasing prevalence of target-mediated drug resistance. Greater than 90% of mutations that confer quinolone resistance act by disrupting enzyme-drug interactions coordinated by a critical water-metal ion bridge. Quinazolinediones are quinolone-like drugs but lack the skeletal features necessary to support the bridge interaction. These compounds are of clinical interest, however, because they retain activity against the most common quinolone resistance mutations. We utilized a chemical biology approach to determine how quinazolinediones overcome quinolone resistance in Bacillus anthracis topoisomerase IV. Quinazolinediones that retain activity against quinolone-resistant topoisomerase IV do so primarily by establishing novel interactions through the C7 substituent, rather than the drug skeleton. Because some quinolones are highly active against human topoisomerase IIα, we also determined how clinically relevant quinolones discriminate between the bacterial and human enzymes. Clinically relevant quinolones display poor activity against topoisomerase IIα because the human enzyme cannot support drug interactions mediated by the water-metal ion bridge. However, the inclusion of substituents that allow quinazolinediones to overcome topoisomerase IV-mediated quinolone resistance can cause cross-reactivity against topoisomerase IIα. Therefore, a major challenge in designing drugs that overcome quinolone resistance lies in the ability to identify substituents that mediate strong interactions with the bacterial, but not the human, enzymes. On the basis of our understanding of quinolone-enzyme interactions, we have identified three compounds that display high activity against quinolone-resistant B. anthracis topoisomerase IV but low activity against human topoisomerase IIα.

  2. Distribution of quinolones, sulfonamides, tetracyclines in aquatic environment and antibiotic resistance in Indochina

    Directory of Open Access Journals (Sweden)

    Satoru eSuzuki

    2012-02-01

    Full Text Available Southeast Asia has become the center of rapid industrial development and economic growth. However, this growth has far outpaced investment in public infrastructure, leading to the unregulated release of many pollutants, including wastewater-related contaminants such as antibiotics. Antibiotics are of major concern because they can easily be released into the environment from numerous sources, and can subsequently induce development of antibiotic-resistant bacteria. Recent studies have shown that for some categories of drugs this source-to-environment antibiotic resistance relationship is more complex. This review summarizes current understanding regarding the presence of quinolones, sulfonamides, and tetracyclines in aquatic environments of Indochina and the prevalence of bacteria resistant to them. Several noteworthy findings are discussed: 1 quinolone contamination and the occurrence of quinolone resistance are not correlated; 2 occurrence of the sul sulfonamide resistance gene varies geographically; and 3 microbial diversity might be related to the rate of oxytetracycline resistance.

  3. The evidence for clonal spreading of quinolone resistance with a particular clonal complex of Campylobacter jejuni.

    Science.gov (United States)

    Kovač, J; Cadež, N; Lušicky, M; Nielsen, E Møller; Ocepek, M; Raspor, P; Možina, S Smole

    2014-12-01

    Campylobacter is the most prevalent cause of bacterial gastroenteritis worldwide and it represents a significant public health risk of increasing severity due to its escalating resistance to clinically important quinolone and macrolide antibiotics. As a zoonotic pathogen Campylobacter is transmitted along the food chain and naturally cycles from environmental waters, feedstuff, animals and food to humans. We determined antibiotic resistance profiles, as well as multilocus sequence types and flaA-SVR types for 52 C. jejuni isolated in Slovenia from human, animal, raw and cured chicken meat and water samples. Twenty-eight different sequence types, arranged in ten clonal complexes, three new allele types and five new sequence types were identified, indicating the relatively high diversity in a small group of strains. The assignment of strains from different sources to the same clonal complexes indicates their transmission along the food supply chain. The most prevalent clonal complex was CC21, which was also the genetic group with 95% of quinolone-resistant strains. Based on the genetic relatedness of these quinolone-resistant strains identified by polymerase chain reaction with a mismatch amplification mutation assay and sequencing of the quinolone resistance-determining region of the gyrA gene, we conclude that the high resistance prevalence observed indicates the local clonal spread of quinolone resistance with CC21.

  4. Characterization of quinolone resistance in Salmonella enterica serovar Indiana from chickens in China.

    Science.gov (United States)

    Lu, Yan; Zhao, Hongyu; Liu, Yuqi; Zhou, Xuping; Wang, Jinyuan; Liu, Tiantian; Beier, Ross C; Hou, Xiaolin

    2015-03-01

    The aim of this study was to characterize the quinolone resistance of Salmonella enterica serovar Indiana isolated from chickens in China. A total of 293 Salmonella strains were isolated from chicken farms and slaughterhouses in Shandong province of China, and 130 (44.4%) were characterized as Salmonella enterica Indiana (chicken farms, n=52 strains; slaughter houses, n=78 strains). All isolate serotypes were tested with the Kauffmann-White classification system and examined for susceptibility to the quinolones: nalidixic acid, enrofloxacin, norfloxacin, and ciprofloxacin. The resistance of the Salmonella Indiana strains to nalidixic acid, enrofloxacin, norfloxacin, and ciprofloxacin were 100, 73.1, 71.2, and 82.7%, and 100, 59.0, 79.5, and 80.2%, respectively. Selected quinolone resistant strains were evaluated for mutations in genes (gyrA, gyrB, parC, and marA) by DNA sequencing. The gyrA mutation was found in all isolates, the parC mutation was only found in some isolates, and the gyrB and marA mutations were not observed. Quinolone resistance was evaluated in the representative isolates by screening for the quinolone resistance determinants, qnrA, qnrB, qnrS, qepA, and aac (6 ')-Ib-cr using PCR technology. The quinolone resistance determinants in Salmonella, qnrA, qnrB, qnrS, and qepA were negative by PCR, but aac(6 ')-Ib-cr had high detection rates of 90.4 and 96.2% in chicken farms and slaughterhouses, respectively. Salmonella Indiana containing the gyrA mutation was prevalent in farms and slaughterhouses and possessed a high frequency of the quinolone resistance determinant aac(6 ')-Ib-cr. These bacteria may have originated from the same source.

  5. Quinolone and macrolide resistance in Campylobacter jejuni and C-coli: Resistance mechanisms and trends in human isolates

    DEFF Research Database (Denmark)

    Engberg, J.; Aarestrup, Frank Møller; Taylor, D. E.

    2001-01-01

    The incidence of human Campylobacter jejuni and C. coli infections has increased markedly in many parts of the world in the last decade as has the number of quinolone-resistant and, to a lesser extent, macrolide-resistant Campylobacter strains causing infections. We review macrolide and quinolone...... maintained, but fluoroquinolones may now be of limited use in the empiric treatment of Campylobacter infections in many regions....

  6. [Bactericidal activity of sitafloxacin and other new quinolones against antimicrobial resistant Streptococcus pneumoniae].

    Science.gov (United States)

    Kobayashi, Intetsu; Kanayama, Akiko; Hasegawa, Miyuki; Kaneko, Akihiro

    2013-02-01

    We conducted a study assess the bactericidal activity of sitafloxacin (STFX) against Streptococcus pneumoniae isolates recovered from respiratory infections including penicillin-resistant (PRSP) isolates, macrolide resistant isolates possessing mefA and ermB resistance genes and quinolone resistance isolates with mutations in gyrA or gyrA and parC. Each isolate tested was grown in hemosupplemented Mueller-Hinton broth and adjusted to approximately 10(5) CFU/ mL. Isolates were than exposed to a Cmax antimicrobial blood level that would be attained with routine antimicrobial administration and an antimicrobial level that would be expected 4 hours post-Cmax (Cmax 4hr). Bactericidal activity was measured for up to 8 hours. Excluding a subset of S. pneumoniae isolates with mutations in the quinolone resistance determining region (QRDR), all quinolones showed bactericidal activity at Cmax and Cmax 4 hr antimicrobial concentrations for up to 8 hours. Against S. pneumoniae isolates with either gyrA or gyrA and parC mutations, bactericidal activity of STFX was shown for up to 4 to 8 hours following Cmax based on a limit of detection of quinolones tested where adjusted to concentrations corresponding to their MICs, STFX showed the most rapid bactericidal activity against PRSP. This rapid bactericidal activity in PRSP is a key to the effectiveness of STFX. Our findings show that beyond inhibition of bacterial replication by blocking their DNA replication pathway and synthesis of proteins, STFX demonstrated characteristics contributing to greater bactericidal activity compared to GRNX. In conclusion, of the newer quinolones, STFX showed the strongest bactericidal activity against S. pneumoniae isolates with mutations in the QRDR which indicates that it may show the most effective clinical utility among the quinolones in respiratory infections.

  7. Quinolone and macrolide resistance in Campylobacter jejuni and C-coli: Resistance mechanisms and trends in human isolates

    DEFF Research Database (Denmark)

    Engberg, J.; Aarestrup, Frank Møller; Taylor, D. E.

    2001-01-01

    The incidence of human Campylobacter jejuni and C. coli infections has increased markedly in many parts of the world in the last decade as has the number of quinolone-resistant and, to a lesser extent, macrolide-resistant Campylobacter strains causing infections. We review macrolide and quinolone...... resistance in Campylobacter and track resistance trends in human clinical isolates in relation to use of these agents in food animals. Susceptibility data suggest that erythromycin and other macrolides should remain the drugs of choice in most regions, with systematic surveillance and central measures...... maintained, but fluoroquinolones may now be of limited use in the empiric treatment of Campylobacter infections in many regions....

  8. In vitro selection of resistance in haemophilus influenzae by 4 quinolones and 5 beta-lactams.

    Science.gov (United States)

    Clark, Catherine; Kosowska, Klaudia; Bozdogan, Bülent; Credito, Kim; Dewasse, Bonifacio; McGhee, Pamela; Jacobs, Michael R; Appelbaum, Peter C

    2004-05-01

    We tested abilities of ciprofloxacin, levofloxacin, gatifloxacin, moxifloxacin, amoxicillin, amoxicillin/clavulanate, cefixime, cefpodoxime, and cefdinir to select resistant mutants in 5 beta-lactamase positive and 5 beta-lactamase negative Haemophilus influenzae strains by single and multistep methodology. In multistep tests, amoxicillin, amoxicillin/clavulanate and cefpodoxime exposure did not cause >4-fold minimum inhibitory concentration (MIC) increase after 50 days. One mutant selected by cefdinir had one amino acid substitution (Gly490Glu) in PBP3 and became resistant to cefdinir. Cefixime exposure caused 8-fold MIC-increase in 1 strain with TEM but the mutant remained cefixime susceptible and had no alteration in PBP3 or TEM. Among 10 strains tested, ciprofloxacin, moxifloxacin, gatifloxacin, levofloxacin caused >4-fold MIC increase in 6, 6, 5, and 2 strain, respectively. Despite the increases in quinolone MICs, none of the mutants became resistant to quinolones by established criteria. Quinolone selected mutants had quindone resistance-determining region (QRDR) alterations in GyrA, GyrB, ParC, ParE. Four quinolone mutants had no QRDR alterations. Among beta-lactams cefdinir and cefixime selected one mutant each with higher MICs however amoxicillin, amoxicillin/clavulanate, and cefpodoxime exposure did not select resistant mutants.

  9. Distinguishing importation from diversification of quinolone-resistant Neisseria gonorrhoeae by molecular evolutionary analysis

    Directory of Open Access Journals (Sweden)

    Dan Michael

    2007-06-01

    Full Text Available Abstract Background Distinguishing the recent introduction of quinolone resistant gonococci into a population from diversification of resistant strains already in the population is important for planning effective infection control strategies. We applied molecular evolutionary analyses to DNA sequences from 9 housekeeping genes and gyrA, parC and porB of 24 quinolone resistant N. gonorrhoeae (QRNG and 24 quinolone sensitive isolates collected in Israel during 2000–2001. Results Phylogenetic and eBURST analyses and estimates of divergence time indicated QRNG were introduced on 3 separate occasions and underwent limited diversification by mutation, deletion and horizontal gene transfer. Reconstruction of N. gonorrhoeae demography showed a slowly declining effective strain population size from 1976 to 1993, rapid decline between 1994 and 1999, and an increase from 1999 to 2001. This is partially attributable to declining gonorrhea case rates from 1973 to 1994. Additional contributing factors are selective sweeps of antibiotic resistant gonococci and increased transmission from sex workers. The abrupt decline in the mid-1990s heralded an increased incidence of gonorrhea from 1997 to the present. The subsequent increase in effective strain population size since 1999 reflects the increased gonococcal census population and introduction of quinolone resistance strains. Conclusion Our study demonstrates the effective use of population genetic approaches to assess recent and historical population dynamics of N. gonorrhoeae.

  10. Resistance to quinolones in Campylobacter jejuni and Campylobacter coli from Danish broilers at farm level

    DEFF Research Database (Denmark)

    Pedersen, Karl; Wedderkopp, A.

    2003-01-01

    Aims : To investigate the prevalence of quinolone resistance among Campylobacter jejuni and Camp. coli isolates from Danish poultry at the farm level, as well as for the whole country. Methods and Results : Data and isolates were collected from a national surveillance of Campylobacter in poultry......-resistant variant. Conclusions : Overall, quinolone resistance among Campylobacter isolates from Danish broilers was 7.5% in 1998 and 1999; it was higher among Camp. coli than Camp. jejuni . Genetic diversity among resistant isolates was lower than among susceptible isolates, and certain clones existed in both...... a resistant and a susceptible variant. Some resistant clones appeared to persist on the farms and were repeatedly isolated from poultry flocks. Significance and Impact of the Study : The study is important for the understanding of persistence and dynamics of Campylobacter in broiler houses. It also highlights...

  11. Occurrence of quinolone- and beta-lactam-resistant Escherichia coli in danish broiler flocks

    DEFF Research Database (Denmark)

    Bortolaia, Valeria; Guardabassi, Luca; Bisgaard, Magne

    ). In Denmark, antimicrobial resistance is annually monitored in both clinical and indicator E. coli isolated from poultry (DANMAP, 2006). However, very little is known on the prevalence of resistance at the flock level. The aim of this study was to determine the prevalence of flocks positive for E. coli...... resistant to quinolones or ß-lactams. Sock samples were collected from 10 broiler parent flocks and 10 broiler offspring flocks. Five pairs of socks were collected from each house. Samples were enriched in McConkey broth and streaked on McConkey agar added with nalidixic acid (32 µg/ml), ciprofloxacin (2 µg...... and nalidixic acid resistances were detected in all flocks. The numbers of E. coli resistant to these drugs were higher in plates from parent flocks than in those from offspring flocks. A broiler parent flock without any history of quinolone usage tested positive for ciprofloxacin-resistant E. coli, although...

  12. Quinolone Resistance among Salmonella enterica from Cattle, Broilers and Swine in Denmark

    DEFF Research Database (Denmark)

    Wiuff, C.; Baggesen, Dorte Lau; Madsen, M.

    2000-01-01

    This study was conducted to determine the susceptibility to nalidixic acid and fluoroquinolones of Salmonella Dublin, S. Enteritidis, and S. Typhimurium isolates from cattle, broilers, and pigs over time in Denmark and to characterise the gyrA, gyrB, and parC genes in quinolone-resistant isolates...

  13. Bartonella bacilliformis, endemic pathogen of the Andean region, is intrinsically resistant to quinolones.

    Science.gov (United States)

    del Valle, Luis J; Flores, Lidia; Vargas, Martha; García-de-la-Guarda, Ruth; Quispe, Ruth L; Ibañez, Zoila B; Alvarado, Débora; Ramírez, Pablo; Ruiz, Joaquim

    2010-06-01

    To analyze the sequence of the region involved in the development of quinolone resistance of the gyrA and parC genes in a series of Bartonella bacilliformis isolates recovered prior to the introduction of quinolones, as well as one clinical isolate recovered in the 1970s, establishing the susceptibility levels to nalidixic acid and ciprofloxacin. Five B. bacilliformis were studied: four isolated before 1957, prior to the introduction of quinolones in clinical practice. The remaining strain was isolated in 1977. A fragment of the gyrA and parC genes was amplified and sequenced. Susceptibility to nalidixic acid and ciprofloxacin was established by the E-test method. All the strains were resistant to nalidixic acid (minimum inhibitory concentration (MIC) >256 mg/l). Three isolates presented decreased susceptibility to ciprofloxacin and two were highly resistant (MIC >32 mg/l). All the strains presented an Ala at position 91 of GyrA and position 85 of ParC. B. bacilliformis presents a constitutive resistance to quinolones, which may be related to the presence of Ala at position 91 of GyrA and 85 of ParC. These results advise against the current clinical guidelines recommending the use of ciprofloxacin to treat bartonellosis in some countries of the Andean area. Copyright 2009 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  14. Comparative Analysis of Quinolone Resistance in Clinical Isolates of Klebsiella pneumoniae and Escherichia coli from Chinese Children and Adults

    Directory of Open Access Journals (Sweden)

    Ying Huang

    2015-01-01

    Full Text Available The objective of this study was to compare quinolone resistance and gyrA mutations in clinical isolates of Klebsiella pneumoniae and Escherichia coli from Chinese adults who used quinolone in the preceding month and children without any known history of quinolone administration. The antimicrobial susceptibilities of 61 isolates from children and 79 isolates from adults were determined. The mutations in the quinolone resistance-determining regions in gyrA gene were detected by PCR and DNA sequencing. Fluoroquinolone resistance and types of gyrA mutations in isolates from children and adults were compared and statistically analyzed. No significant differences were detected in the resistance rates of ciprofloxacin and levofloxacin between children and adults among isolates of the two species (all P>0.05. The double mutation Ser83→Leu + Asp87→Asn in the ciprofloxacin-resistant isolates occurred in 73.7% isolates from the children and 67.9% from the adults, respectively (P=0.5444. Children with no known history of quinolone administration were found to carry fluoroquinolone-resistant Enterobacteriaceae isolates. The occurrence of ciprofloxacin resistance and the major types of gyrA mutations in the isolates from the children were similar to those from adults. The results indicate that precautions should be taken on environmental issues resulting from widespread transmission of quinolone resistance.

  15. Comparative analysis of quinolone resistance in clinical isolates of Klebsiella pneumoniae and Escherichia coli from Chinese children and adults.

    Science.gov (United States)

    Huang, Ying; Ogutu, James O; Gu, Jiarui; Ding, Fengshu; You, Yuhong; Huo, Yan; Zhao, Hong; Li, Wenjing; Zhang, Zhiwei; Zhang, Wenli; Chen, Xiaobei; Fu, Yingmei; Zhang, Fengmin

    2015-01-01

    The objective of this study was to compare quinolone resistance and gyrA mutations in clinical isolates of Klebsiella pneumoniae and Escherichia coli from Chinese adults who used quinolone in the preceding month and children without any known history of quinolone administration. The antimicrobial susceptibilities of 61 isolates from children and 79 isolates from adults were determined. The mutations in the quinolone resistance-determining regions in gyrA gene were detected by PCR and DNA sequencing. Fluoroquinolone resistance and types of gyrA mutations in isolates from children and adults were compared and statistically analyzed. No significant differences were detected in the resistance rates of ciprofloxacin and levofloxacin between children and adults among isolates of the two species (all P > 0.05). The double mutation Ser83→Leu + Asp87→Asn in the ciprofloxacin-resistant isolates occurred in 73.7% isolates from the children and 67.9% from the adults, respectively (P = 0.5444). Children with no known history of quinolone administration were found to carry fluoroquinolone-resistant Enterobacteriaceae isolates. The occurrence of ciprofloxacin resistance and the major types of gyrA mutations in the isolates from the children were similar to those from adults. The results indicate that precautions should be taken on environmental issues resulting from widespread transmission of quinolone resistance.

  16. Prevalence of quinolone resistance determinants in non-typhoidal Salmonella isolates from human origin in Extremadura, Spain.

    Science.gov (United States)

    Campos, Maria Jorge; Palomo, Gonzalo; Hormeño, Lorena; Herrera-León, Silvia; Domínguez, Lucas; Vadillo, Santiago; Píriz, Segundo; Quesada, Alberto

    2014-05-01

    Resistance to the quinolones nalidixic acid (NAL) and ciprofloxacin (CIP) and the occurrence of quinolone resistance determinants have been investigated in 300 non-typhoidal Salmonella from human origin, isolated in the years between 2004 and 2008, in 6 hospitals within Extremadura (Spain). Salmonella Enteritidis was the major serotype found among quinolone-resistant isolates, most of which were clustered by clonal analysis to a single clone, which presented D87 or S83 substitutions in GyrA. Eleven isolates presented the non-classical quinolone resistance phenotype (resistance to CIP and susceptibility to NAL), lacking mutations in the quinolone resistance determinant region of topoisomerase genes. Among them, one Salmonella Typhimurium isolate carried a qnrS1 gene in a low-molecular-weight plasmid, pQnrS1-HLR25, identical to plasmids previously found in the UK, Taiwan, and USA. The occurrence of this genetic element could represent a risk for the horizontal transmission of quinolone resistance among Enterobacteriaceae in the Iberian Peninsula.

  17. Quinolone Resistance among Salmonella enterica from Cattle, Broilers and Swine in Denmark

    DEFF Research Database (Denmark)

    Wiuff, C.; Baggesen, Dorte Lau; Madsen, M.

    2000-01-01

    This study was conducted to determine the susceptibility to nalidixic acid and fluoroquinolones of Salmonella Dublin, S. Enteritidis, and S. Typhimurium isolates from cattle, broilers, and pigs over time in Denmark and to characterise the gyrA, gyrB, and parC genes in quinolone-resistant isolates......, and one from 1999 were resistant to nalidixic acid. All the nalidixic acid-resistant isolates had reduced susceptibility to fluoroquinolones. Sequence analysis of the gyrA gene in 37 nalidixic-resistant isolates identified two different base substitutions at codon serine-83 and two at aspartate-87...

  18. Dynamics of quinolone resistance in fecal Escherichia coli of finishing pigs after ciprofloxacin administration.

    Science.gov (United States)

    Huang, Kang; Xu, Chang-Wen; Zeng, Bo; Xia, Qing-Qing; Zhang, An-Yun; Lei, Chang-Wei; Guan, Zhong-Bin; Cheng, Han; Wang, Hong-Ning

    2014-09-01

    Escherichia coli resistance to quinolones has now become a serious issue in large-scale pig farms of China. It is necessary to study the dynamics of quinolone resistance in fecal Escherichia coli of pigs after antimicrobial administration. Here, we present the hypothesis that the emergence of resistance in pigs requires drug accumulation for 7 days or more. To test this hypothesis, 26 pigs (90 days old, about 30 kg) not fed any antimicrobial after weaning were selected and divided into 2 equal groups: the experimental (EP) group and control (CP) group. Pigs in the EP group were orally treated daily with 5 mg ciprofloxacin/kg of body weight for 30 days, and pigs in the CP group were fed a normal diet. Fresh feces were collected at 16 time points from day 0 to day 61. At each time point, ten E. coli clones were tested for susceptibility to quinolones and mutations of gyrA and parC. The results showed that the minimal inhibitory concentration (MIC) for ciprofloxacin increased 16-fold compared with the initial MIC (0.5 µg/ml) after ciprofloxacin administration for 3 days and decreased 256-fold compared with the initial MIC (0.5 µg/ml) after ciprofloxacin withdrawal for 26 days. GyrA (S83L, D87N/ D87Y) and parC (S80I) substitutions were observed in all quinolone-resistant E. coli (QREC) clones with an MIC ≥8 µg/ml. This study provides scientific theoretical guidance for the rational use of antimicrobials and the control of bacterial resistance.

  19. Genetic analysis of a pediatric clinical isolate of Moraxella catarrhalis with resistance to macrolides and quinolones.

    Science.gov (United States)

    Iwata, Satoshi; Sato, Yoshitake; Toyonaga, Yoshikiyo; Hanaki, Hideaki; Sunakawa, Keisuke

    2015-04-01

    During the surveillance conducted in 2012 by the Drug-resistant Pathogen Surveillance Group in Pediatric Infectious Disease, we isolated a strain of Moraxella catarrhalis that demonstrated resistance to both macrolides and quinolones from a male pediatric patient aged 1.5 years who had developed acute bronchitis. Then we evaluated the susceptibility of this strain to different types of antibacterial agents and conducted a genetic analysis. The results of the susceptibility evaluation showed that the MIC values of azithromycin, clarithromycin, and rokitamycin were >64 μg/mL, >64 μg/mL, and 4 μg/mL, respectively; clearly demonstrating resistance to macrolides. The MIC values of the quinolones levofloxacin, tosufloxacin, and garenoxacin were 4 μg/mL, 2 μg/mL, and 1 μg/mL, respectively; indicating decreased susceptibility. The genetic analysis of this strain revealed one mutation in 23s rRNA with a replacement of adenine by thymine at nucleotide position 2330 (A2330T) and another mutation in gyrB at nucleotide position 1481 by replacement of adenine with guanine (A1481G) that caused a substitution of the 494 th asparagine acid by glycine, as being associated with the observed resistance to macrolides and quinolones, respectively. Similar to drug-resistant bacteria Streptococcus pneumoniae and Haemophilus influenzae, the prevalence of which has recently increased, the treatment of drug-resistant M. catarrhalis infections is considered difficult due to the development of resistance to different types of antibacterial agents. It is vital to maintain an unwavering focus on the trend toward an increasing number of drug-resistant M. catarrhalis strains and ensure the proper use of each antibacterial agent.

  20. ESBL, plasmidic AmpC, and associated quinolone resistance determinants in coliforms isolated from hospital effluent: first report of qnrB2, qnrB9, qnrB19, and blaCMY-4 in Algeria.

    Science.gov (United States)

    Anssour, Lynda; Messai, Yamina; Derkaoui, Meriem; Alouache, Souhila; Estepa, Vanesa; Somalo, Sergio; Torres, Carmen; Bakour, Rabah

    2014-04-01

    The characterization of extended-spectrum beta-lactamases , plasmidic AmpC (pAmpC), and associated plasmid-mediated quinolone resistance (PMQR) determinants in cefotaxime-resistant coliforms isolated from hospital effluent in Algiers showed blaCTX-M genes in 89%, blaTEM-1 in 79·8%, and pAmpC genes (blaCIT) in 2·7% isolates. Association of ISEcp1B with blaCTX-M was found in all CTX-M+ isolates, and 97·2% harboured class 1 integrons. Sequencing showed blaCTX-M-15, blaCTX-M-3, and blaCMY-4 genes. blaCTX-M-3 and blaCTX-M-15 were located in Inc L/M conjugative plasmids. The PMQR determinants identified were qnrB1, qnrB2, qnrB9, qnrB19, qnrS2, and aac(6')-Ib-cr. qnrB2, qnrB9, qnrB19, and blaCMY-4 are described for the first time in Algeria and qnrB19 for the first time in non-clinical environments. This study highlights the major potential role of hospital effluents as providers of resistance genes to natural environments.

  1. Impact of the E540V amino acid substitution in GyrB of Mycobacterium tuberculosis on quinolone resistance.

    Science.gov (United States)

    Kim, Hyun; Nakajima, Chie; Yokoyama, Kazumasa; Rahim, Zeaur; Kim, Youn Uck; Oguri, Hiroki; Suzuki, Yasuhiko

    2011-08-01

    Amino acid substitutions conferring resistance to quinolones in Mycobacterium tuberculosis have generally been found within the quinolone resistance-determining regions (QRDRs) in the A subunit of DNA gyrase (GyrA) rather than the B subunit of DNA gyrase (GyrB). To clarify the contribution of an amino acid substitution, E540V, in GyrB to quinolone resistance in M. tuberculosis, we expressed recombinant DNA gyrases in Escherichia coli and characterized them in vitro. Wild-type and GyrB-E540V DNA gyrases were reconstituted in vitro by mixing recombinant GyrA and GyrB. Correlation between the amino acid substitution and quinolone resistance was assessed by the ATP-dependent DNA supercoiling assay, quinolone-inhibited supercoiling assay, and DNA cleavage assay. The 50% inhibitory concentrations of eight quinolones against DNA gyrases bearing the E540V amino acid substitution in GyrB were 2.5- to 36-fold higher than those against the wild-type enzyme. Similarly, the 25% maximum DNA cleavage concentrations were 1.5- to 14-fold higher for the E540V gyrase than for the wild-type enzyme. We further demonstrated that the E540V amino acid substitution influenced the interaction between DNA gyrase and the substituent(s) at R-7, R-8, or both in quinolone structures. This is the first detailed study of the contribution of the E540V amino acid substitution in GyrB to quinolone resistance in M. tuberculosis.

  2. Cellular Response to Ciprofloxacin in Low-Level Quinolone-Resistant Escherichia coli

    Directory of Open Access Journals (Sweden)

    Jesús Machuca

    2017-07-01

    Full Text Available Bactericidal activity of quinolones has been related to a combination of DNA fragmentation, reactive oxygen species (ROS production and programmed cell death (PCD systems. The underlying molecular systems responsible for reducing bactericidal effect during antimicrobial therapy in low-level quinolone resistance (LLQR phenotypes need to be clarified. To do this and also define possible new antimicrobial targets, the transcriptome profile of isogenic Escherichia coli harboring quinolone resistance mechanisms in the presence of a clinical relevant concentration of ciprofloxacin was evaluated. A marked differential response to ciprofloxacin of either up- or downregulation was observed in LLQR strains. Multiple genes implicated in ROS modulation (related to the TCA cycle, aerobic respiration and detoxification systems were upregulated (sdhC up to 63.5-fold in mutants with LLQR. SOS system components were downregulated (recA up to 30.7-fold. yihE, a protective kinase coding for PCD, was also upregulated (up to 5.2-fold. SdhC inhibition sensitized LLQR phenotypes (up to ΔLog = 2.3 after 24 h. At clinically relevant concentrations of ciprofloxacin, gene expression patterns in critical systems to bacterial survival and mutant development were significantly modified in LLQR phenotypes. Chemical inhibition of SdhC (succinate dehydrogenase validated modulation of ROS as an interesting target for bacterial sensitization.

  3. Characterization of antimicrobial resistance in Salmonella enterica food and animal isolates from Colombia: identification of a qnrB19-mediated quinolone resistance marker in two novel serovars

    DEFF Research Database (Denmark)

    Karczmarczyk, M.; Martins, M.; McCusker, M.

    2010-01-01

    Ninety-three Salmonella isolates recovered from commercial foods and exotic animals in Colombia were studied. The serotypes, resistance profiles and where applicable the quinolone resistance genes were determined. Salmonella Anatum (n=14), Uganda (19), Braenderup (10) and Newport (10) were the most...... hitherto unrecognized in various Salmonella serovars in Colombia. We also report unusual high-level quinolone resistance in the absence of any DNA gyrase mutations in serovars S. Carrau, Muenchen and Uganda....

  4. 养殖动物及人分离大肠埃希菌染色体和质粒介导氟喹诺酮耐药机制的研究%Chromosome-and plasmid-mediated fluoroquinolones-resistance in Escherichia coli strains isolated from food animals and healthy people around farm

    Institute of Scientific and Technical Information of China (English)

    李景云; 崔生辉; 王云鹏; 胡昌勤; 金少鸿; 马越

    2008-01-01

    目的 探讨从养殖动物及周围人群分离的大肠埃希菌染色体和质粒介导氟喹诺酮耐药机制. 方法 纸片扩散法和肉汤稀释法检测氟喹诺酮抗菌药物及其他抗生素的耐药性表型.PCR扩增DNA解旋酶(gyrA和gyrB)和拓扑异构酶IV(parC和parE)基因的喹诺酮耐药决定区、导致喹诺酮类抗生素耐药质粒的部分基因(qnr)以及氨基糖苷类抗生素乙酰转移酶Ib亚型cr变异体编码基因[aac(6')-I b-or],PCR产物进行直接测序.接合试验确定aac(6')-I b-cr酶的可转移性以及在氟喹诺酮耐药中的作用. 结果 鸡来源的大肠埃希菌对常用抗生素的耐药率明显高于猪和周围人群来源菌株.在PCR检测的64株大肠埃希菌中,环丙沙星MIC值大于1μg/ml以上的53株均存在gyrA和/或/parC基因上出现两个位点突变和氨基酸替代,环丙沙星的MIC>16μg/ml的菌株parE基因也发生了点突变及相应氨基酸替代.未发现gyrB亚单位有氨基酸替代.鸡来源28株菌和猪来源9株菌中分别有7株(25.O%)和1株(11.1%)携带有aac(6')-I b-cr基因;aac(6')-I b-cr基因可使环丙沙星、诺氟沙星乙酰化而降低药物抗菌活性. 结论 gyrA、parC和parE碱基突变导致氨基酸置换的数量与菌株对氟喹诺酮类耐药水平呈正相关,携带aac(6')-I b-cr基因的质粒在细菌氟喹诺酮耐药上也具有一定作用.%Objective To study on chromosome-and plasmid-mediated fluoroquinolones-resistant in Escherichia coli isolated from fecal samples of chicken,swine and people around the farm.Methods Anti-microbial susceptibility testing was carried out by disk diffusion testing and bmth microdilution testing.gyrA,gyrB,parC,pareE,qnr and aac(6')-I b-cr were examined by PCR,and the products were sequenced.Ex-presion of aac(6')-I b-cr by conjunction was tested too.Results The resistance to antimicmbial agents was much higher in strains isolated from chicken than that from swine and human.Among the E coli strains

  5. Lack of efflux mediated quinolone resistance in Salmonella enterica serovars Typhi and Paratyphi A

    Directory of Open Access Journals (Sweden)

    Sylvie eBaucheron

    2014-01-01

    Full Text Available Salmonella enterica serovars Typhi and Paratyphi A isolates from human patients in France displaying different levels of resistance to quinolones or fluoroquinolones were studied for resistance mechanisms to these antimicrobial agents. All resistant isolates carried either single or multiple target gene mutations (i.e. in gyrA, gyrB, or parC correlating with the resistance levels observed. Active efflux, through upregulation of multipartite efflux systems, has also been previously reported as contributing mechanism for other serovars. Therefore, we investigated also the occurrence of non-target gene mutations in regulatory regions affecting efflux pump expression. However, no mutation was detected in these regions in both Typhi and Paratyphi isolates of this study. Besides, no overexpression of the major efflux systems was observed for these isolates. Nevertheless, a large deletion of 2334 bp was identified in the acrS-acrE region of all S. Typhi strains but which did not affect the resistance phenotype. As being specific to S. Typhi, this deletion could be used for specific molecular detection purposes. In conclusion, the different levels of quinolone or FQ resistance in both S. Typhi and S. Paratyphi A seem to rely only on target modifications.

  6. Presence of qnr gene in Escherichia coli and Klebsiella pneumoniae resistant to ciprofloxacin isolated from pediatric patients in China

    Directory of Open Access Journals (Sweden)

    Wang Chuanqing

    2008-05-01

    Full Text Available Abstract Background Quinolone resistance in Enterobacteriaceae results mainly from mutations in type II DNA topoisomerase genes and/or changes in the expression of outer membrane and efflux pumps. Several recent studies have indicated that plasmid-mediated resistance mechanisms also play a significant role in fluoroquinolone resistance, and its prevalence is increasing worldwide. In China, the presence of the qnr gene in the clinical isolates of Enterobacteriaceae has been reported, but this transmissible quinolone resistance gene has not been detected in strains isolated singly from pediatric patients. Because quinolones associated with a variety of adverse side effects on children, they are not authorized for pediatric use. This study therefore aimed to investigate the presence of the qnr gene in clinical isolates of E. coli and K. pneumoniae from pediatric patients in China. Methods A total 213 of non-repetitive clinical isolates resistant to ciprofloxacin from E. coli and K. pneumoniae were collected from hospitalized patients at five children's hospital in Beijing, Shanghai, Guangzhou, and Chongqing. The isolates were screened for the plasmid-mediated quinolone resistance genes of qnrA, qnrB, and qnrS by PCR. Transferability was examined by conjugation with the sodium azide-resistant E. coli J53. All qnr-positive were analyzed for clonality by enterobacterial repetitive intergenic consensus (ERIC-PCR. Results The study found that 19 ciprofloxacin-resistant clinical isolates of E. coli and K. pneumoniae were positive for the qnr gene, and most of the qnr positive strains were ESBL producers. Conjugation experiments showed that quinolone resitance could be transferred to recipients. Apart from this, different DNA banding patterns were obtained by ERIC-PCR from positive strains, which means that most of them were not clonally related. Conclusion This report on transferable fluoroquinolone resistance due to the qnr gene among E. coli and K

  7. Increasing resistance to quinolones: A four-year prospective study of urinary tract infection pathogens

    Directory of Open Access Journals (Sweden)

    Orhiosefe Omigie

    2009-08-01

    Full Text Available Orhiosefe Omigie, Lawrence Okoror, Patience Umolu, Gladys IkuuhDepartment of Microbiology, Ambrose Alli University, Ekpoma, NigeriaAbstract: A four-year prospective study was carried out to determine the incidence and rate of development of resistance by common urinary tract infection (UTI pathogens to quinolone antimicrobial agents. Results show that there is high intrinsic resistance to the quinolones among strains of Pseudomonas aeruginosa (43.4%, Escherichia coli (26.3%, and Proteus spp. (17.1%. Over four years, rising rates of resistance were observed in P. aeruginosa (14.6% increase, Staphylococcus aureus (9.8%, and E. coli (9.7%. The highest potency was exhibited by ciprofloxacin (91.2%, levofloxacin (89.2%, and moxifloxacin (85.1%, while there were high rates of resistance to nalidixic acid (51.7% and pefloxacin (29.0%. Coliforms, particularly E. coli (>45%, remain the most prevalent causative agents of UTI while females within the age range of 20–50 years were most vulnerable to UTI.Keywords: UTI, microorganisms, antibiotics, resistance

  8. 一株耐碳青霉烯类的阴沟肠杆菌的KPC酶检测%Detection of plasmid-mediated carbapenem-hydrolyzing β-lactamase KPC-2 in a strain of carbapenem-resistant Enterobacter cloacae

    Institute of Scientific and Technical Information of China (English)

    蔡加昌; 周宏伟; 陈功祥; 张嵘

    2008-01-01

    Objective To investigate the mechanism of carbapenem resistance in Enterobacter cloacae.Methods A carbapenem-resistant strain of E.cloacae (strain ZY1465)was isolated.Antibiotic susceptibilities were determined by agar dilution method.Conjugation experiments were carried out in mixed broth cultures.Plasmid DNA preparations were obtained by using an alkalinelysis technique and were digested by various endonucleases;The crude β-lactamase extracts of E.cloacae and E.coli transconjugant were subjected to analytical isoelectric focusing(IEF).Specific PCR amplification and DNA sequence analysis were preformed to confirm the β-lactamase type.Outer membrane proteins(OMPs)were isolated and examined by urea-sodium dodecyl sulfate-polyacrylamide gel electrophoresis.Results The E. cloacae isolate showed resistance against carbapenems.The MICs of imipenem and meropenem were both 32 μg/ml.The isolate was also resistant strongly against penicillins,cephalosporins,cefoxitin,aztreonam,quinolones,and aminoglycosides.Conjugation studies with E.coli resulted in the transfer of reduced carbapenem susceptibility from E.cloacae isolate.Plasmid restriction analysis showed identical restriction profiles between the transconjugants of E. cloacae ZY1465 and Serratia marcescens ZN008.Isoelectric focusing demonstrated six β-lactamases,with the isoelectrie points(pls)of5.4,6.7,7.3,7.8,7.9,and 8.6,in E.cloacae ZY1465.and only one β-lactamase with the pI of 6.7 in transconiugant.Specific PCR amplification and DNA sequence analysis confirmed that E.cloacae ZY1465 harbored TEM-1,KPC-2,DHA-1,CTX-M-14,CTX-M-3 and chromosomal AmpC(not detected in IEF)genes.Urea-SDS-PAGE analysis of OMPs showed that E. cloacae ZY1465 lacked an OMP of approximately 38 000 Da which was present in E. cloacae ATCC13047.Conclusion It is the first detection of plasmid-mediated carbapenemhydrolyzing β-lactamase KPC-2 in a clinical isolate of E.cloacae from China.Production of multiple β-lactamases,especially KPC-2 and

  9. Resistance patterns to beta-lactams and quinolones in clinical isolates of bacteria from Cuban hospitals.

    Science.gov (United States)

    Gonzáles, I; Niebla, A; Vallin, C

    1995-01-01

    The resistance patterns to 26 beta-lactams and 8 quinolones of clinical isolates from Cuban hospitals were evaluated using the disk susceptibility test, according to the NCCLS guidelines (1992). The genera studied were Escherichia sp (320), Enterobacter sp (10), Klebsiella sp (90), Proteus sp (10), Pseudomonas sp (90), Serratia sp (20), and Staphylococcus sp (80). Higher resistance to beta-lactams was observed in the genera Pseudomonas, Escherichia and Klebsiella. For fluoroquinolones we found no significant resistance, with the exception of the genus Klebsiella. The most effective antibiotics were cephalosporins of the second and third generations, fluoroquinolones, and non-classical beta-lactams (cephamycins, moxalactam and monobactams). On the contrary, a pronounced resistance was found to penicillin, oxacillin, ticarcillin, ampicillin, methicillin, nalidixic acid and cinoxacin. These resistance patterns correspond to the high consumption of these antibiotics throughout the country.

  10. 喹诺酮类药对常见病原菌耐药变迁与耐药机制初探%Change of resistance and drug resistance mechanism of quinolone against common bacteria in clinical practice

    Institute of Scientific and Technical Information of China (English)

    黄小玲; 林渡娣; 杨春燕; 黄福新; 袁慧文

    2011-01-01

    Objective: To understand change of resistance and drug resistance mechanism of quinolone against common bacteria in clinical practice.Methods: To identify by Freneh Vitek-32 AMS analyzer, susceptibility test was performed with disc diffusion testing.The results were evaluated according to the standards of US Clinical and Laboratory Standards Institute (CLSI) to initially discuss bacterial resistance mechanisms by literature review.Results: Test results of resistance for 4 060 strains of common G+ and G- bacteria to quinolone indicated that drug resistance had increased in various degrees, the order of their resistance was: ciprofloxacin>levofloxacin>gatifloxacin>moxifloxacin, ciprofloxacin resistance against MRSA and MRCNS became more than 95.0% and 70.0% respectively.They were regarded as highly resistant to clinical medicine and should not be the first choice in clinical treatment any more.As for bacterial resistance mechanism it was mainly because of the decrease for intracellular drug accumulation concentration of bacteria and mutations at the target enzyme or target site, as well as resistance or multiple drug resistance caused by pLasmid mediation.Conclusion:Drug resistance against quinolone is increased annually.from the perspective of resistance mechanism, except drug sensitivity test should be performed in clinical practice, medicated drugs and dosage should also be optimized according to PK/PD parameters.%目的:了解喹诺酮类药对临床常见病原菌的耐药性变迁及耐药机制.方法:采用法国Vitek-32 AMS分析仪进行鉴定,纸片扩散法进行药敏试验;根据美国临床实验室标准化研究所(CLSI)标准判断结果,并查阅文献初探细菌耐药机制.结果:依据喹诺酮类药对常见G+和G-菌4060株耐药性的监测结果,耐药性均有不同程度增加,其耐药性排序为环丙沙星>左氧氟沙星>加替沙星>莫西沙星,环丙沙星对MRSA和MRCNS的耐药率分别超过95.0%和70.0%,已高度耐

  11. High-level quinolone resistance is associated with the overexpression of smeVWX in Stenotrophomonas maltophilia clinical isolates.

    Science.gov (United States)

    García-León, G; Ruiz de Alegría Puig, C; García de la Fuente, C; Martínez-Martínez, L; Martínez, J L; Sánchez, M B

    2015-05-01

    Stenotrophomonas maltophilia is the only known bacterium in which quinolone-resistant isolates do not present mutations in the genes encoding bacterial topoisomerases. The expression of the intrinsic quinolone resistance elements smeDEF, smeVWX and Smqnr was analysed in 31 clinical S. maltophilia isolates presenting a minimum inhibitory concentration (MIC) range to ciprofloxacin between 0.5 and > 32 μg/mL; 11 (35.5%) overexpressed smeDEF, 2 (6.5%) presenting the highest quinolone MICs overexpressed smeVWX and 1 (3.2%) overexpressed Smqnr. Both strains overexpressing smeVWX presented changes at the Gly266 position of SmeRv, the repressor of smeVWX. Changes at the same position were previously observed in in vitro selected S. maltophilia quinolone-resistant mutants, indicating this amino acid is highly relevant for the activity of SmeRv in repressing smeVWX expression. For the first time SmeVWX overexpression is associated with quinolone resistance of S. maltophilia clinical isolates.

  12. Prevalence and molecular characterization of plasmid- mediated ...

    African Journals Online (AJOL)

    lactamase genes among nosocomial Staphylococcus aureus drug resistance isolates in Taiwan. .... Table 2: Plasmid profiles of the clinical antibiotic-resistant pathogens. Strain. Profile .... Madec J. Characterization of clinical canine methicillin-.

  13. QUINOLONE- AND ETA-LACTAM- RESISTANCE IN Escherichia coli FROM DANISH AND ITALIAN BROILER FLOCKS

    Directory of Open Access Journals (Sweden)

    M. Trevisani

    2009-03-01

    Full Text Available The prevalence of quinolone- and -lactam-resistant E. coli was investigated among healthy broiler flocks in Denmark and Italy. In Denmark, sock samples were collected from 10 parent flocks and 10 offspring flocks, according to the procedure currently used for the surveillance of Salmonella in the EU. Samples were enriched in McConkey broth and streaked on McConkey agar plates added with nalidixic acid (32 g/ml, ciprofloxacin (2 g/ml, ampicillin (32 g/ml, cefotaxime (2 g/ml or ceftiofur (8 g/ml. The -glucuronidase test was performed for verification of presumptive E. coli. The same methods were used to analyse sock samples collected from 6 Italian broiler flocks. PCR with primers for the CTX-M-type extended-spectrum -lactamases (ESBLs was performed on cephalosporin-resistant isolates. While resistance to ampicillin and nalidixic acid was widespread in both countries, resistance to ciprofloxacin and cephalosporins was more common among Italian flocks. In Denmark, ciprofloxacin resistance was only detected in 1 parent flock without any history of quinolone usage and none of the flocks was positive for cephalosporin-resistant E. coli. In Italy, resistance to ciprofloxacin was detected in all flocks and resistance to ceftiofur and cefotaxime were detected in 5 flocks. Primers specific for the CTX-M-type ESBLs generated PCR amplicons from isolates from 3 of these flocks. In industrialized countries, the poultry production system is highly standardized, and therefore comparable. However, the use of broad-spectrum antimicrobials is particularly limited in Danish poultry production. Accordingly, the results of this study could reflect the different policies in antimicrobial usage between the two countries.

  14. Structure based in silico analysis of quinolone resistance in clinical isolates of Salmonella Typhi from India.

    Science.gov (United States)

    Kumar, Manoj; Dahiya, Sushila; Sharma, Priyanka; Sharma, Sujata; Singh, Tej P; Kapil, Arti; Kaur, Punit

    2015-01-01

    Enteric fever is a major cause of morbidity in several parts of the Indian subcontinent. The treatment for typhoid fever majorly includes the fluoroquinolone group of antibiotics. Excessive and indiscriminate use of these antibiotics has led to development of acquired resistance in the causative organism Salmonella Typhi. The resistance towards fluoroquinolones is associated with mutations in the target gene of DNA Gyrase. We have estimated the Minimum Inhibitory Concentration (MIC) of commonly used fluoroquinolone representatives from three generations, ciprofloxacin, ofloxacin, levofloxacin and moxifloxacin, for 100 clinical isolates of Salmonella Typhi from patients in the Indian subcontinent. The MICs have been found to be in the range of 0.032 to 8 μg/ml. The gene encoding DNA Gyrase was subsequently sequenced and point mutations were observed in DNA Gyrase in the quinolone resistance determining region comprising Ser83Phe/Tyr and Asp87Tyr/Gly. The binding ability of these four fluoroquinolones in the quinolone binding pocket of wild type as well as mutant DNA Gyrase was computationally analyzed by molecular docking to assess their differential binding behaviour. This study has revealed that mutations in DNA Gyrase alter the characteristics of the binding pocket resulting in the loss of crucial molecular interactions and consequently decrease the binding affinity of fluoroquinolones with the target protein. The present study assists in understanding the underlying molecular and structural mechanism for decreased fluoroquinolone susceptibility in clinical isolates as a consequence of mutations in DNA Gyrase.

  15. Structure Based In Silico Analysis of Quinolone Resistance in Clinical Isolates of Salmonella Typhi from India

    Science.gov (United States)

    Sharma, Priyanka; Sharma, Sujata; Singh, Tej P.; Kapil, Arti; Kaur, Punit

    2015-01-01

    Enteric fever is a major cause of morbidity in several parts of the Indian subcontinent. The treatment for typhoid fever majorly includes the fluoroquinolone group of antibiotics. Excessive and indiscriminate use of these antibiotics has led to development of acquired resistance in the causative organism Salmonella Typhi. The resistance towards fluoroquinolones is associated with mutations in the target gene of DNA Gyrase. We have estimated the Minimum Inhibitory Concentration (MIC) of commonly used fluoroquinolone representatives from three generations, ciprofloxacin, ofloxacin, levofloxacin and moxifloxacin, for 100 clinical isolates of Salmonella Typhi from patients in the Indian subcontinent. The MICs have been found to be in the range of 0.032 to 8 μg/ml. The gene encoding DNA Gyrase was subsequently sequenced and point mutations were observed in DNA Gyrase in the quinolone resistance determining region comprising Ser83Phe/Tyr and Asp87Tyr/Gly. The binding ability of these four fluoroquinolones in the quinolone binding pocket of wild type as well as mutant DNA Gyrase was computationally analyzed by molecular docking to assess their differential binding behaviour. This study has revealed that mutations in DNA Gyrase alter the characteristics of the binding pocket resulting in the loss of crucial molecular interactions and consequently decrease the binding affinity of fluoroquinolones with the target protein. The present study assists in understanding the underlying molecular and structural mechanism for decreased fluoroquinolone susceptibility in clinical isolates as a consequence of mutations in DNA Gyrase. PMID:25962113

  16. Structure based in silico analysis of quinolone resistance in clinical isolates of Salmonella Typhi from India.

    Directory of Open Access Journals (Sweden)

    Manoj Kumar

    Full Text Available Enteric fever is a major cause of morbidity in several parts of the Indian subcontinent. The treatment for typhoid fever majorly includes the fluoroquinolone group of antibiotics. Excessive and indiscriminate use of these antibiotics has led to development of acquired resistance in the causative organism Salmonella Typhi. The resistance towards fluoroquinolones is associated with mutations in the target gene of DNA Gyrase. We have estimated the Minimum Inhibitory Concentration (MIC of commonly used fluoroquinolone representatives from three generations, ciprofloxacin, ofloxacin, levofloxacin and moxifloxacin, for 100 clinical isolates of Salmonella Typhi from patients in the Indian subcontinent. The MICs have been found to be in the range of 0.032 to 8 μg/ml. The gene encoding DNA Gyrase was subsequently sequenced and point mutations were observed in DNA Gyrase in the quinolone resistance determining region comprising Ser83Phe/Tyr and Asp87Tyr/Gly. The binding ability of these four fluoroquinolones in the quinolone binding pocket of wild type as well as mutant DNA Gyrase was computationally analyzed by molecular docking to assess their differential binding behaviour. This study has revealed that mutations in DNA Gyrase alter the characteristics of the binding pocket resulting in the loss of crucial molecular interactions and consequently decrease the binding affinity of fluoroquinolones with the target protein. The present study assists in understanding the underlying molecular and structural mechanism for decreased fluoroquinolone susceptibility in clinical isolates as a consequence of mutations in DNA Gyrase.

  17. Emergence of quinolone resistance among extended-spectrum beta-lactamase-producing Enterobacteriaceae in the Central African Republic: genetic characterization

    Directory of Open Access Journals (Sweden)

    Frank Thierry

    2011-08-01

    Full Text Available Abstract Background Cross-resistance to quinolones and beta-lactams is frequent in Enterobacteriaceae, due to the wide use of these antibiotics clinically and in the food industry. Prescription of one of these categories of antibiotic may consequently select for bacteria resistant to both categories. Genetic mechanisms of resistance may be secondary to a chromosomal mutation located in quinolone resistance determining region of DNA gyrase or topoisomerase IV or to a plasmid acquisition. The insertion sequence ISCR1 is often associated with qnr and may favour its dissemination in Gram-negative bacteria. The aim of this study was to determine the genetic mechanism of quinolone resistance among extended-spectrum beta-lactamase-producing Enterobacteriaceae strains in the Central African Republic. Findings Among seventeen ESBL-producing Enterobacteriaceae isolated from urine, pus or stool between January 2003 and October 2005 in the Central African Republic, nine were resistant to ciprofloxacin (seven from community patients and two from hospitalized patients. The ESBL were previously characterized as CTX-M-15 and SHV-12. Susceptibility to nalidixic acid, norfloxacin and ciprofloxacin, and the minimal inhibitory concentrations of these drugs were determined by disc diffusion and agar dilution methods, respectively. The presence of plasmid-borne ISCR1-qnrA region was determined by PCR and amplicons, if any, were sent for sequencing. Quinolone resistance determining region of DNA gyrase gyrA gene was amplified by PCR and then sequenced for mutation characterization. We found that all CTX-M-producing strains were resistant to the tested quinolones. All the isolates had the same nucleotide mutation at codon 83 of gyrA. Two Escherichia coli strains with the highest MICs were shown to harbour an ISCR1-qnrA1 sequence. This genetic association might favour dissemination of resistance to quinolone and perhaps other antibiotics among Enterobacteriaceae

  18. Mechanisms of quinolone resistance in Salmonella spp. / Mecanismos de resistência às quinolonas em Salmonella spp.

    Directory of Open Access Journals (Sweden)

    Tereza Cristina Rocha Moreira de Oliveira

    2010-07-01

    Full Text Available Salmonellosis is a common and widespread zoonotic disease of humans and a frequent cause of foodborne disease. Treatment of severe and systemic salmonellosis is usually done with fluoroquinolones. In this review resistance mechanisms of Salmonella to quinolones are discussed. Single point mutations in the quinolone resistant determining region (QRDR of the gyrA gene may be sufficient to generate high levels of resistance to non-fluorated quinolones and also may decrease the fluoroquinolones susceptibility. Other resistance mechanisms that should be considered are mutations in parC gene, the possibility of acquiring resistance through plasmidial transference and hyper-expression of efflux pumps. Fluoroquinolones resistance is still relatively uncommon in Salmonella compared to other species belonging to the Enterobacteriaceae family. However, the more careful use of fluoroquinolones in veterinary and human medicine is essential to decrease the selective pressure which can avoid the emergence and spread of resistant clones and consequently maintain the clinical efficacy of this group of antibiotics.A salmonelose é uma zoonose de importância mundial e uma das mais freqüentes doenças de origem alimentar. As fluoroquinolonas são a principal opção para o tratamento de salmoneloses graves ou sistêmicas. Esta revisão de literatura teve como objetivo apresentar os principais mecanismos envolvidos na resistência de Salmonella spp a estes antimicrobianos. Mutações de ponto na Região Determinante de Resistência à Quinolona (QRDR do gene gyrA podem gerar altos níveis de resistência a quinolonas não-fluoradas, além de reduzir a suscetibilidade as fluoroquinolonas. Outros mecanismos de resistência que também precisam ser considerados são as mutações no gene parC, a possibilidade do envolvimento de plasmídios de resistência e o sistema de efluxo ativo. A resistência às fluoroquinolonas ainda é incomum em Salmonella spp., quando

  19. Detection of mutations in mtrR gene in quinolone resistant strains of N.gonorrhoeae isolated from India

    Directory of Open Access Journals (Sweden)

    S V Kulkarni

    2015-01-01

    Full Text Available Background and Objectives: Emergence of multi-drug resistant Neisseria gonorrhoeae resulting from new genetic mutation is a serious threat in controlling gonorrhea. This study was undertaken to identify and characterise mutations in the mtrR genes in N.gonorrhoeae isolates resistant to six different antibiotics in the quinolone group. Materials and Methods: The Minimum inhibitory concentrations (MIC of five quinolones for 64 N.gonorrhoeae isolates isolated during Jan 2007-Jun 2009 were determined by E-test method. Mutations in MtrR loci were examined by deoxyribonucleic acid (DNA sequencing. Results: The proportion of N.gonorrhoeae strains resistant to anti-microbials was 98.4% for norfloxacin and ofloxacin, 96.8% for enoxacin and ciprofloxacin, 95.3% for lomefloxacin. Thirty-one (48.4% strains showed mutation (single/multiple in mtrR gene. Ten different mutations were observed and Gly-45 → Asp, Tyr-105 → His being the most common observed mutation. Conclusion: This is the first report from India on quinolone resistance mutations in MtrRCDE efflux system in N.gonorrhoeae. In conclusion, the high level of resistance to quinolone and single or multiple mutations in mtrR gene could limit the drug choices for gonorrhoea.

  20. Alarmingly High Segregation Frequencies of Quinolone Resistance Alleles within Human and Animal Microbiomes Are Not Explained by Direct Clinical Antibiotic Exposure.

    Science.gov (United States)

    Field, Wesley; Hershberg, Ruth

    2015-05-26

    Antibiotic resistance poses a major threat to human health. It is therefore important to characterize the frequency of resistance within natural bacterial environments. Many studies have focused on characterizing the frequencies with which horizontally acquired resistance genes segregate within natural bacterial populations. Yet, very little is currently understood regarding the frequency of segregation of resistance alleles occurring within the housekeeping targets of antibiotics. We surveyed a large number of metagenomic datasets extracted from a large variety of host-associated and non host-associated environments for such alleles conferring resistance to three groups of broad spectrum antibiotics: streptomycin, rifamycins, and quinolones. We find notable segregation frequencies of resistance alleles occurring within the target genes of each of the three antibiotics, with quinolone resistance alleles being the most frequent and rifamycin resistance alleles being the least frequent. Resistance allele frequencies varied greatly between different phyla and as a function of environment. The frequency of quinolone resistance alleles was especially high within host-associated environments, where it averaged an alarming ∼ 40%. Within host-associated environments, resistance to quinolones was most often conferred by a specific resistance allele. High frequencies of quinolone resistance alleles were also found within hosts that were not directly treated with antibiotics. Therefore, the high segregation frequency of quinolone resistance alleles occurring within the housekeeping targets of antibiotics in host-associated environments does not seem to be the sole result of clinical antibiotic usage.

  1. Quinolone- and ß-lactam-resistance in Escherichia coli from Danish and Italian broiler flocks

    DEFF Research Database (Denmark)

    Bortolaia, Valeria; Guardabassi, Luca; Bisgaard, Magne

    Frederiksberg C, Denmark 2Dipartimento di Sanità Pubblica Veterinaria e Patologia Animale, Facoltà di Medicina Veterinaria, Università di Bologna, 40064 Ozzano Emilia (BO), Italy   The prevalence of quinolone- and ß-lactam-resistant E. coli was investigated among broiler flocks in Denmark and Italy. In Denmark...

  2. Risk factors for quinolone-resistant Escherichia coli in feces from preweaned dairy calves and postpartum dairy cows.

    Science.gov (United States)

    Duse, Anna; Waller, Karin Persson; Emanuelson, Ulf; Unnerstad, Helle Ericsson; Persson, Ylva; Bengtsson, Björn

    2015-09-01

    Quinolone resistance may emerge in gut bacteria (e.g., in Escherichia coli) of animals. Such bacteria could cause infections in the animal itself or be transmitted to humans via the food chain. Quinolone resistance is also observed in fecal E. coli of healthy dairy cattle, but the prevalence varies between farms, not solely as a result of varying degree of fluoroquinolone exposure. The objective of this study was to identify risk factors for the fecal shedding of quinolone-resistant E. coli (QREC) from dairy calves and postpartum cows. Rectal swabs from 15 preweaned calves and 5 postpartum cows per farm were collected on 23 Swedish dairy farms to determine the prevalence of QREC. Risk factors for the shedding of QREC were investigated using multivariable statistical models. Quinolone-resistant E. coli were found on all but one farm. Factors associated with QREC shedding by calves were being younger than 18 d, being fed milk from cows treated with antimicrobials, recent use of fluoroquinolones in the herd, carriage of QREC by postpartum cows, and using the calving area never or rarely as a sick pen compared with often. Factors associated with QREC shedding by cows were calving in group pens or freestalls compared with single pens or tiestalls, purchasing cattle, sharing animal transports with other farmers, and poor farm hygiene. Proper biosecurity and improved hygiene, as well as minimizing fluoroquinolone exposure and waste milk feeding, may be important factors to reduce the burden of QREC on dairy farms.

  3. Quinolone resistance and ESBL/AmpC’s in commensal Escherichia coli in veal calves : prevalence and molecular characterization

    NARCIS (Netherlands)

    Hordijk, J.

    2013-01-01

    In this thesis the prevalence and molecular characteristics of resistance to (fluoro)quinolones and Extended Spectrum Cephalosporins (ESC) in veal calves were described using Escherichia coli as an indicator organism. Ciprofloxacin and nalidixic acid were used as indicator antimicrobials for quinolo

  4. Quinolone resistance and ESBL/AmpC’s in commensal Escherichia coli in veal calves : prevalence and molecular characterization

    NARCIS (Netherlands)

    Hordijk, J.

    2013-01-01

    In this thesis the prevalence and molecular characteristics of resistance to (fluoro)quinolones and Extended Spectrum Cephalosporins (ESC) in veal calves were described using Escherichia coli as an indicator organism. Ciprofloxacin and nalidixic acid were used as indicator antimicrobials for quinolo

  5. A function of SmeDEF, the major quinolone resistance determinant of Stenotrophomonas maltophilia, is the colonization of plant roots.

    Science.gov (United States)

    García-León, Guillermo; Hernández, Alvaro; Hernando-Amado, Sara; Alavi, Peyman; Berg, Gabriele; Martínez, José Luis

    2014-08-01

    Quinolones are synthetic antibiotics, and the main cause of resistance to these antimicrobials is mutation of the genes encoding their targets. However, in contrast to the case for other organisms, such mutations have not been found in quinolone-resistant Stenotrophomonas maltophilia isolates, in which overproduction of the SmeDEF efflux pump is a major cause of quinolone resistance. SmeDEF is chromosomally encoded and highly conserved in all studied S. maltophilia strains; it is an ancient element that evolved over millions of years in this species. It thus seems unlikely that its main function would be resistance to quinolones, a family of synthetic antibiotics not present in natural environments until the last few decades. Expression of SmeDEF is tightly controlled by the transcriptional repressor SmeT. Our work shows that plant-produced flavonoids can bind to SmeT, releasing it from smeDEF and smeT operators. Antibiotics extruded by SmeDEF do not impede the binding of SmeT to DNA. The fact that plant-produced flavonoids specifically induce smeDEF expression indicates that they are bona fide effectors regulating expression of this resistance determinant. Expression of efflux pumps is usually downregulated unless their activity is needed. Since smeDEF expression is triggered by plant-produced flavonoids, we reasoned that this efflux pump may have a role in the colonization of plants by S. maltophilia. Our results showed that, indeed, deletion of smeE impairs S. maltophilia colonization of plant roots. Altogether, our results indicate that quinolone resistance is a recent function of SmeDEF and that colonization of plant roots is likely one original function of this efflux pump.

  6. Coexistence of blaOXA-23 with armA in quinolone-resistant Acinetobacter baumannii from a Chinese university hospital.

    Science.gov (United States)

    Shen, Min; Luan, Guangxin; Wang, Yanhong; Chang, Yaowen; Zhang, Chi; Yang, Jingni; Deng, Shanshan; Ling, Baodong; Jia, Xu

    2016-03-01

    A total of 101 Acinetobacter baumannii isolates were collected to determine the mechanisms of quinolone resistance and investigate the occurrence of carbapenem and high-level aminoglycoside resistance genes among quinolone-resistant strains. Among 77 quinolone-resistant A. baumannii harbored mutations of gyrA and parC, 41 isolates, which belonged to European clone II, had resistance to aminoglycosides and carbapenems due to the expression of armA and acquisition of blaOXA-23. Most of sequence type belonged to clonal complex 92. These results suggested hospital dissemination of multidrug-resistant A. baumannii carrying blaOXA-23, armA, and mutations of quinolone resistance-determining regions in western China.

  7. In vivo sequential selection of Escherichia coli with topoisomerase- and efflux-mediated misleading quinolone resistance phenotypes.

    Science.gov (United States)

    Smati, Mounira; Emond, Jean-Philippe; Arlet, Guillaume; Tankovic, Jacques

    2012-02-01

    Two mutants of Escherichia coli (V1 and V2) with acquired mechanisms of resistance to fluoroquinolones were isolated sequentially from blood cultures of a patient with cholangiocarcinoma treated repeatedly with ofloxacin; a third mutant (V3) was isolated under ciprofloxacin therapy. All mutants were related clonally. V1 was susceptible to quinolones but with diminished susceptibility to ofloxacin. V2 was hypersusceptible to nalidixic acid but had high-level resistance to ofloxacin. V3 was resistant to all quinolones. Ofloxacin selected for original gyrA and parC mutations, leading to the unusual and misleading resistance phenotypes of V1 and V2, whereas efflux played a major role in the increased resistance of V3.

  8. Quinolone resistant Aeromonas spp. as carriers and potential tracers of acquired antibiotic resistance in hospital and municipal wastewater.

    Science.gov (United States)

    Varela, Ana Rita; Nunes, Olga C; Manaia, Célia M

    2016-01-15

    Members of the genus Aeromonas are recognized carriers of antibiotic resistance in aquatic environments. However, their importance on the spread of resistance from hospital effluents to the environment is poorly understood. Quinolone resistant Aeromonas spp. (n = 112) isolated from hospital effluent (HE) and from raw (RWW) and treated wastewater (TWW) of the receiving urban wastewater treatment plant (UWTP) were characterized. Species identification and genetic intraspecies diversity were assessed based on the 16S rRNA, cpn60 and gyrB genes sequence analysis. The antibiotic resistance phenotypes and genotypes (qnrA, qnrB, qnrC, qnrD, qnrS, qnrVC; qepA; oqxAB; aac(6′)-Ib-cr; blaOXA; incU) were analyzed in function of the origin and taxonomic group. Most isolates belonged to the species Aeromonas caviae and Aeromonas hydrophila (50% and 41%, respectively). The quinolone and the beta-lactamase resistance genes aac(6′)-Ib-cr and blaOXA, including gene blaOXA-101, identified for the first time in Aeromonas spp., were detected in 58% and 56% of the isolates, respectively, with identical prevalence in HE and UWTP wastewater. In contrast, the gene qnrS2 was observed mainly in isolates from the UWTP (51%) and rarely in HE isolates (3%), suggesting that its origin is not the clinical setting. Bacterial groups and genes that allow the identification of major routes of antibiotic resistance dissemination are valuable tools to control this problem. In this study, it was concluded that members of the genus Aeromonas harboring the genes aac(6′)-Ib-cr and blaOXA are relevant tracers of antibiotic resistance dissemination in wastewater habitats, while those yielding the gene qnrS2 allow the traceability from non-clinical sources.

  9. Study on plasmid-mediated quinolone resistance genes in clinical isolates of Enterobacter aerogenes%产气肠杆菌质粒介导喹诺酮类耐药基因研究

    Institute of Scientific and Technical Information of China (English)

    罗新华; 李少禧; 周铁丽; 费静娴; 侯佳惠; 包其郁; 曹建明

    2011-01-01

    @@ 产气肠杆菌广泛存在于自然界和健康人肠道中,是医院感染的重要病原菌,可引起泌尿道、呼吸道、伤口及血液等多种感染.喹诺酮类药物由于抗菌谱广、抗菌作用强,广泛用于临床抗感染治疗.

  10. plasmid mediated resistance in multidrug resistant bacteria isolated ...

    African Journals Online (AJOL)

    User

    3Department of Paediatrics, Ahmadu Bello University Teaching Hospital, Zaria ... The knowledge of the epidemiological and antimicrobial pattern of common pathogens that cause septicaemia is useful for ..... commonly prescribed antibiotics in the locality investigated. ... to monitor and restrict the use and sale of antibiotics.

  11. In Vitro Resistance Development to Nemonoxacin in Streptococcus pneumoniae: A Unique Profile for a Novel Nonfluorinated Quinolone

    Science.gov (United States)

    Roychoudhury, Siddhartha; Makin, Kelly; Twinem, Tracy; Leunk, Robert

    2016-01-01

    Selection of resistant strains in Streptococcus pneumoniae was studied in vitro with nemonoxacin, a novel nonfluorinated quinolone (NFQ), in comparison with quinolone benchmarks, ciprofloxacin, garenoxacin, and gatifloxacin. In stepwise resistance selection studies, a 256-fold loss of potency was observed after three to four steps of exposure to ciprofloxacin or garenoxacin. In contrast, the loss of potency was limited to eightfold after three steps of exposure to nemonoxacin and repeated attempts to isolate highly resistant organisms after four steps of exposure yielded isolates that could not be subcultured in liquid medium. The quinolone resistance-determining regions of the target genes, parC, parE, gyrA, and gyrB, were analyzed through DNA sequencing. Known mutations, especially in the hotspots of parC and gyrA, were selected with exposure to garenoxacin, ciprofloxacin, and gatifloxacin. In contrast, mutations selected with nemonoxacin were limited to GyrA, GyrB, and ParE, sparing ParC, which is known as a key driver of resistance in clinical isolates of S. pneumoniae. This observation is consistent with previous data using other NFQs, which showed no loss of potency due to ParC mutations in clinical isolates. This apparently unique feature of nemonoxacin is potentially attributable to the structural uniqueness of the NFQs, distinguishing them from the fluoroquinolones that are commonly prescribed for infections by S. pneumoniae. PMID:27267788

  12. Molecular characterization of genes encoding the quinolone resistance determining regions of Malaysian Streptococcus pneumoniae strains

    Directory of Open Access Journals (Sweden)

    Kumari N

    2008-01-01

    Full Text Available Genes encoding the quinolones resistance determining regions (QRDRs in Streptococcus pneumoniae were detected by PCR and the sequence analysis was carried out to identify point mutations within these regions. The study was carried out to observe mutation patterns among S. pneumoniae strains in Malaysia. Antimicrobial susceptibility testing of 100 isolates was determined against various antibiotics, out of which 56 strains were categorised to have reduced susceptibility to ciprofloxacin (≥2 μg/mL. These strains were subjected to PCR amplification for presence of the gyrA, parC , gyrB and parE genes. Eight representative strains with various susceptibilities to fluoroquinolones were sequenced. Two out of the eight isolates that were sequenced were shown to have a point mutation in the gyrA gene at position Ser81. The detection of mutation at codon Ser81 of the gyrA gene suggested the potential of developing fluoroquinolone resistance among S. pneumoniae isolates in Malaysia. However, further experimental work is required to confirm the involvement of this mutation in the development of fluoroquinolone resistance in Malaysia.

  13. High Resolution Melting Analysis for Rapid Mutation Screening in Gyrase and Topoisomerase IV Genes in Quinolone-Resistant Salmonella enterica

    Directory of Open Access Journals (Sweden)

    Soo Tein Ngoi

    2014-01-01

    Full Text Available The increased Salmonella resistance to quinolones and fluoroquinolones is a public health concern in the Southeast Asian region. The objective of this study is to develop a high resolution melt curve (HRM assay to rapidly screen for mutations in quinolone-resistant determining region (QRDR of gyrase and topoisomerase IV genes. DNA sequencing was performed on 62 Salmonella strains to identify mutations in the QRDR of gyrA, gyrB, parC, and parE genes. Mutations were detected in QRDR of gyrA (n=52; S83F, S83Y, S83I, D87G, D87Y, and D87N and parE (n=1; M438I. Salmonella strains with mutations within QRDR of gyrA are generally more resistant to nalidixic acid (MIC 16>256 μg/mL. Mutations were uncommon within the QRDR of gyrB, parC, and parE genes. In the HRM assay, mutants can be distinguished from the wild-type strains based on the transition of melt curves, which is more prominent when the profiles are displayed in difference plot. In conclusion, HRM analysis allows for rapid screening for mutations at the QRDRs of gyrase and topoisomerase IV genes in Salmonella. This assay markedly reduced the sequencing effort involved in mutational studies of quinolone-resistance genes.

  14. Changes of the Quinolones Resistance to Gram-positive Cocci Isolated during the Past 8 Years in the First Bethune Hospital

    Science.gov (United States)

    Xu, Jiancheng; Chen, Qihui; Yao, Hanxin; Zhou, Qi

    This study was to investigate the quinolones resistance to gram-positive cocci isolated in the First Bethune Hospital during the past 8 years. Disk diffusion test was used to study the antimicrobial resistance. The data were analyzed by WHONET 5 software according to Clinical and Laboratory Standards Institute (CLSI). The rates of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococci (MRCNS) were 50.8%∼83.3% and 79.4%∼81.5%during the past 8 years, respectively. In recent 8 years, the quinolones resistance to gram-positive cocci had increased. Monitoring of the quinolones resistance to gram-positive cocci should be strengthened. The change of the antimicrobial resistance should be investigated in order to guide rational drug usage in the clinic and prevent bacterial strain of drug resistance from being transmitted.

  15. Molecular characterization of quinolone resistance mechanisms and extended-spectrum β-lactamase production in Escherichia coli isolated from dogs.

    Science.gov (United States)

    Meireles, D; Leite-Martins, L; Bessa, L J; Cunha, S; Fernandes, R; de Matos, A; Manaia, C M; Martins da Costa, P

    2015-08-01

    The increasing prevalence of antimicrobial resistances is now a worldwide problem. Investigating the mechanisms by which pets harboring resistant strains may receive and/or transfer resistance determinants is essential to better understanding how owners and pets can interact safely. Here, we characterized the genetic determinants conferring resistance to β-lactams and quinolones in 38 multidrug-resistant Escherichia coli isolated from fecal samples of dogs, through PCR and sequencing. The most frequent genotype included the β-lactamase groups TEM (n=5), and both TEM+CTX-M-1 (n=5). Within the CTX-M group, we identified the genes CTX-M-32, CTX-M-1, CTX-M-15, CTX-M-55/79, CTX-M-14 and CTX-M-2/44. Thirty isolates resistant to ciprofloxacin presented two mutations in the gyrA gene and one or two mutations in the parC gene. A mutation in gyrA (reported here for the first time), due to a transversion and transition (TCG→GTG) originating a substitution of a serine by a valine in position 83 was also detected. The plasmid-encoded quinolone resistance gene, qnrs1, was detected in three isolates. Dogs can be a reservoir of genetic determinants conferring antimicrobial resistance and thus may play an important role in the spread of antimicrobial resistance to humans and other co-habitant animals.

  16. Association of mutation patterns in GyrA and ParC genes with quinolone resistance levels in lactic acid bacteria.

    Science.gov (United States)

    Li, Shaoying; Li, Zhen; Wei, Wan; Ma, Chunyan; Song, Xiaomin; Li, Shufen; He, Wenying; Tian, Jianjun; Huo, Xiaoyan

    2015-02-01

    The quinolone resistance of 19 lactic acid bacterial strains belonging to the genera Enterococcus and Lactobacillus isolated from the natural fermented koumiss and yoghurt were investigated. The objective of this study was to determine the quinolone resistance levels and to explore the association of the resistance with the mutation patterns in gyrA and parC genes, as is currently recommended by the Food and Agriculture Organization/World Health Organization Joint Expert Committee in Guidelines for Evaluation of Probiotics in Food for probiotic lactic acid bacteria drug resistance in 2001. The Oxford Cup method and double-tube dilution method were used to determine the quinolone resistance levels of the isolated strains. Generally, all of the 19 strains showed resistance towards norfloxacin and ciprofloxacin when the Oxford cup method was used, whereas the incidence was lower (to norfloxacin 89.5% and to ciprofloxacin 68.4%) when minimum inhibitory concentration breakpoints (CLSI M100-S23) were tested. Furthermore, gene sequencing was conducted on gyrA and parC of topoisomerase II of these isolated strains. The genetic basis for quinolone resistance may be closely related to mutations in gyrA genes as there were 10 mutation sites in amino-acid sequences encoded by gyrA genes in 10 quinolone resistance strains and 14 mutation sites in Enterococcus durans HZ28, whereas no typical mutations were detected in parC genes.

  17. Quinolone- and ß-lactam-resistance in Escherichia coli from Danish and Italian broiler flocks

    DEFF Research Database (Denmark)

    Bortolaia, Valeria; Guardabassi, Luca; Bisgaard, Magne

    , sock samples were collected from 10 parent flocks and 10 offspring flocks, according to the procedure currently used for the surveillance of Salmonella in the EU. Samples were enriched in McConkey broth and streaked on McConkey agar plates added with nalidixic acid (32 µg/ml), ciprofloxacin (2 µg...... on cephalosporin-resistant isolates. While resistance to ampicillin and nalidixic acid was widespread in both countries, resistance to ciprofloxacin and cephalosporins was more common among Italian flocks. In Denmark, ciprofloxacin resistance was only detected in one parent flock without any history of quinolone...... usage and none of the flocks was positive for cephalosporin-resistant E. coli. In Italy, resistance to ciprofloxacin was detected in all flocks and resistances to ceftiofur and cefotaxime were detected in five flocks. Primers specific for the CTX-M-type ESBLs generated PCR amplicons from isolates from...

  18. Characterization of Plasmid-Mediated AmpC and Carbapenemases among Iranain Nosocomial Isolates of Klebsiella pneumoniae Using Phenotyping and Genotyping Methods

    NARCIS (Netherlands)

    A. Japoni-Nejad (Alireza); E. Ghaznavi Rad (Ehsanollah); A.F. van Belkum (Alex)

    2014-01-01

    textabstractObjectives: Plasmid-mediated AmpC β-lactamases (PMABLs) and carbapenemases are emerging groups of antimicrobial-resistance determinants. The aims of the study were to evaluate the occurrence of PMABLs and carbapenemases in clinical isolates of Klebsiella pneumoniae and compare the test p

  19. Characterization of Plasmid-Mediated AmpC and Carbapenemases among Iranain Nosocomial Isolates of Klebsiella pneumoniae Using Phenotyping and Genotyping Methods

    NARCIS (Netherlands)

    A. Japoni-Nejad (Alireza); E. Ghaznavi Rad (Ehsanollah); A.F. van Belkum (Alex)

    2014-01-01

    textabstractObjectives: Plasmid-mediated AmpC β-lactamases (PMABLs) and carbapenemases are emerging groups of antimicrobial-resistance determinants. The aims of the study were to evaluate the occurrence of PMABLs and carbapenemases in clinical isolates of Klebsiella pneumoniae and compare the test p

  20. Impact of a short exposure to levofloxacin on faecal densities and relative abundance of total and quinolone-resistant Enterobacteriaceae.

    Science.gov (United States)

    Bernard, J; Armand-Lefèvre, L; Luce, E; El Mniai, A; Chau, F; Casalino, E; Andremont, A; Ruppé, E

    2016-07-01

    Emergence of resistant Enterobacteriaceae in the intestinal microbiota during antibiotic treatment is well documented but its early dynamic is not. Here, we compared the densities of total Enterobacteriaceae and relative abundance (RA) of quinolone-resistant Enterobacteriaceae (QRE) in the first stool passed by patients who had a short exposure to levofloxacin (levofloxacin, n=12) or not (control, n=8). Mean densities (SD) (log CFU/g stool) of total Enterobacteriaceae were lower in the levofloxacin group than in the control group-3.4 (1.6) versus 6.7 (1.7), respectively, p Enterobacteriaceae and the QRE-RA.

  1. Determinants of quinolone resistance in Escherichia coli causing community-acquired urinary tract infection in Bejaia, Algeria.

    Science.gov (United States)

    Betitra, Yanat; Teresa, Vinuesa; Miguel, Viñas; Abdelaziz, Touati

    2014-06-01

    To investigate the mechanisms of quinolone resistance and the association with other resistance markers among Esherichia coli (E. coli) strains isolated from outpatient with urinary tract infection in north of Algeria. A total of 30 nalidixic acid-resistant E. coli isolates from outpatient with urinary tract infections from January 2010 to April 2011 in north of Algeria (Bejaia) were studied. Antimicrobial susceptibility was determined by disc diffusion assay, minimal inhibitory concentrations (MIC) of quinolone were determined by microdilution. Mutations in the Quinolone Resistance-Determining Region (QRDR) of gyrA and parC genes and screening for qnr (A, B and S) and bla genes were done by PCR and DNA sequencing. Most of the E. coli isolates (56.66%) were shown to carry mutations in gyrA and parC (gyrA: Ser83Leu + Asp87Asn and parC:Ser80Ile). While, 16.66% had only an alteration in gyrA: Ser83Leu. One isolate produced qnrB-like and two qnrS-like. Four isolates were CTX-M-15 producers associated with TEM-1 producing in one case. Co-expression of blaCTX-M-15 and qnrB was determined in one E. coli isolate. Our findings suggested the community emergence of gyrA and parC alterations and Qnr determinants that contributed to the development and spread of fluoroquinolone resistance in Algerian E. coli isolates. Copyright © 2014 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

  2. Molecular study on some antibiotic resistant genes in Salmonella spp. isolates

    Science.gov (United States)

    Nabi, Ari Q.

    2017-09-01

    Studying the genes related with antimicrobial resistance in Salmonella spp. is a crucial step toward a correct and faster treatment of infections caused by the pathogen. In this work Integron mediated antibiotic resistant gene IntI1 (Class I Integrase IntI1) and some plasmid mediated antibiotic resistance genes (Qnr) were scanned among the isolated non-Typhoid Salmonellae strains with known resistance to some important antimicrobial drugs using Sybr Green real time PCR. The aim of the study was to correlate the multiple antibiotics and antimicrobial resistance of Salmonella spp. with the presence of integrase (IntI1) gene and plasmid mediated quinolone resistant genes. Results revealed the presence of Class I Integrase gene in 76% of the isolates with confirmed multiple antibiotic resistances. Moreover, about 32% of the multiple antibiotic resistant serotypes showed a positive R-PCR for plasmid mediated qnrA gene encoding for nalidixic acid and ciprofloxacin resistance. No positive results could be revealed form R-PCRs targeting qnrB or qnrS. In light of these results we can conclude that the presence of at least one of the qnr genes and/or the presence of Integrase Class I gene were responsible for the multiple antibiotic resistance to for nalidixic acid and ciprofloxacin from the studied Salmonella spp. and further studies required to identify the genes related with multiple antibiotic resistance of the pathogen.

  3. Quinolone-resistance in Salmonella is associated with decreased mRNA expression of virulence genes invA and avrA, growth and intracellular invasion and survival.

    Science.gov (United States)

    Wang, Yu-Ping; Li, Lin; Shen, Jian-Zhong; Yang, Fu-Jiang; Wu, Yong-Ning

    2009-02-01

    A variety of environmental factors, such as oxygen, pH, osmolarity and antimicrobial agents, modulate the expression of Salmonella pathogenicity islands (SPI) genes. This study investigated SPI-1 gene expression and the pathogenicity of quinolone-resistant Salmonella. mRNA expression levels of the invA and avrA genes, located in SPI-1, in quinolone-susceptible and quinolone-resistant Salmonella strains were determined using real-time fluorescent quantitative reverse transcription-polymerase chain reaction (RT-PCR). Twenty-five quinolone-resistant Salmonella mutants were derived from quinolone-susceptible strains by multiple-passage selection through increasing concentrations of ciprofloxacin in vitro, while an additional 15 strains were quinolone-resistant Salmonella clinical isolates. Sequence analysis showed no gene deletion or point mutations of nine SPI-1 genes (including invA and avrA) occurred in either the selected or clinical quinolone-resistant strains, while a single gyrA point mutation (S83F) was observed in all 40 quinolone-resistant strains. The mRNA expression levels of invA and avrA were significantly decreased (P<0.005) in quinolone-resistant strains (clinically acquired or experimentally selected in vitro), compared to the quinolone-susceptible strains. The resistant strains also had a slower growth rate combined with decreased epithelial cell invasion and intracellular replication in epithelial cells and macrophages. The results suggest that quinolone-resistance may be associated with lower virulence and pathogenicity than in quinolone-susceptible strains.

  4. Identification of the main quinolone resistance determinant in Campylobacter jejuni and Campylobacter coli by MAMA-DEG PCR.

    Science.gov (United States)

    Hormeño, Lorena; Palomo, Gonzalo; Ugarte-Ruiz, María; Porrero, M Concepción; Borge, Carmen; Vadillo, Santiago; Píriz, Segundo; Domínguez, Lucas; Campos, Maria J; Quesada, Alberto

    2016-03-01

    Among zoonotic diseases, campylobacteriosis stands out as the major bacterial infection producing human gastroenteritis. Antimicrobial therapy, only recommended in critical cases, is challenged by resistance mechanisms that should be unambiguously detected for achievement of effective treatments. Quinolone (ciprofloxacin) resistance of Campylobacter jejuni and Campylobacter coli, the 2 main Campylobacter detected in humans, is conferred by the mutation gyrA C-257-T, which can be genotyped by several methods that require a previous identification of the pathogen species to circumvent the sequence polymorphism of the gene. A multiplex PCR, based on degenerated oligonucleotides, has been designed for unambiguous identification of the quinolone resistance determinant in Campylobacter spp. isolates. The method was verified with 249 Campylobacter strains isolated from humans (141 isolates) and from the 3 most important animal sources for this zoonosis: poultry (34 isolates), swine (38 isolates), and cattle (36 isolates). High resistance to ciprofloxacin, MIC above 4μg/mL, linked to the mutated genotype predicted by MAMA-DEG PCR (mismatch amplification mutation assay PCR with degenerated primers) was found frequently among isolates from the different hosts.

  5. Surveillance on antibiotic susceptibility and plasmid-mediated resistance of Neisseria gonorrhoeae in Panyu Guangzhou%广州市番禺区淋病奈瑟球菌的耐药性及质粒介导耐药株的流行趋势

    Institute of Scientific and Technical Information of China (English)

    郭炽星; 张晖燕; 蒋敏慧; 徐碧红; 黎敬忠; 罗嘉莉

    2014-01-01

    Objective To monitor the minimum inhibitory concentration (MIC) of 5 antibiotics for Neisseria gonorrhoeae and its plasmid-mediated resistant strains,and to analyze the trend of drug resistant strains penicillinase-producing Neisseria gonorrhoeae (PPNG) and tetracycline-resistant Neisseria gonorrhoeae (TRNG).Methods Four hundred and thirty-six isolates of Neisseria gonorrhoeae were collected from Panyu Institute of Chronic Disease,Guangzhou from 2008 and 2012.The production of β-lactamase was determined by paper acidometric method.The agar dilution method was used to determine the MIC of spectinomycin,cefatriaxone,penicillin,tetracycline and ciprofloxacin.Results Out of 436 isolates,147 (33.72%) were plasmid-mediated PPNG strains and 222(50.92%) were TRNG strains.During the 5-year period,the prevalence of PPNG and TRNG ranged from 24.32% to 45.59% and from 21.31% to 67.57%,with significant differences(x2=11.659,38.464,P all<0.05).None of the strains were resistant to spectinomycin and ceftriaxone,but the ceftriaxone intermediate rate fluctuated from 26.13% to 72.13% with significant differences (x2=39.720,P<0.01),and their MIC50 and MIC90 were all in the sensitive ranges.However,the MIC50 and MIC90 of penicillin,tetracycline and ciprofloxacin changed greatly,and were significantly higher than resistant standards,with the resistance rates of 76.37% (333/ 436),88.76% (387/436) and 94.26% (411/436),respectively.Conclusions From 2008 to 2012,spectinomycin and ceftriaxone are both sensitive to Neisseria gonorrhoeae,and are recommended as the first-line antibiotics against gonorrhea.The MIC50 and MIC90 of penicillin,tetracycline and ciprofloxacin are unstable and rise above the resistant standards,indicating that it is inappropriate to use them as the first-line antibiotics in treatment of gonorrhea.%目的 监测淋病奈瑟球菌(淋球菌)对5种抗菌药物的最小抑菌浓度(MIC)和质粒介导耐药株,分析产β-内酰胺酶淋球

  6. Characterization of the quinolone resistant determining regions in clinical isolates of pneumococci collected in Canada

    Directory of Open Access Journals (Sweden)

    Melano Roberto

    2010-01-01

    Full Text Available Abstract Background The objective of this study was to examine Streptococcus pneumoniae isolates collected from a longitudinal surveillance program in order to determine their susceptibility to currently used fluoroquinolones and of the frequency and type of mutations in the quinolone-resistant determining regions (QRDRs of their parC and gyrA genes. Methods The Canadian Bacterial Surveillance Network has been collecting clinical isolates of S. pneumoniae from across Canada since 1988. Broth microdilution susceptibility testing was carried out according to the Clinical and Laboratory Standards Institute guidelines. The QRDRs of the parC and gyrA genes were sequenced for all isolates with ciprofloxacin MIC ≥ 4 mg/L, and a large representative sample of isolates (N = 4,243 with MIC ≤ 2 mg/L. Results A total of 4,798 out of 30,111 isolates collected from 1988, and 1993 to 2007 were studied. Of those isolates that were successfully sequenced, 184 out of 1,032 with mutations in parC only, 11 out of 30 with mutations in gyrA only, and 292 out of 298 with mutations in parC and gyrA were considered resistant to ciprofloxacin (MIC ≥ 4 mg/L. The most common substitutions in the parC were at positions 137 (n = 722, 79 (n = 209, and 83 (n = 56, of which substitutions at positions 79 and 83 were associated with 4-fold increase in MIC to ciprofloxacin, whereas substitutions at position 137 had minimal effect on the ciprofloxacin MIC. A total of 400 out of 622 isolates with Lys-137 parC mutation belonged to serotypes 1, 12, 31, 7A, 9V, 9N and 9L, whereas only 49 out of 3064 isolates with no mutations belonged to these serotypes. Twenty-one out of 30 isolates with substitutions at position 81 of the gyrA gene had an increased MIC to ciprofloxacin. Finally, we found that isolates with mutations in both parC and gyrA were significantly associated with increased MIC to fluoroquinolones. Conclusions Not all mutations, most frequently Lys-137, found in the

  7. Quinolone resistant campylobacter infections in Denmark: risk factors and clinical consequences

    DEFF Research Database (Denmark)

    Engberg, J.; Neimann, J.; Nielsen, E. M.

    2004-01-01

    origin) was associated with a decreased risk. Typing data showed an association between strains from retail food products and broiler chickens and quinolone-sensitive domestically acquired C. jejuni infections. An association between treatment with a fluoroquinolone before stool-specimen collection...

  8. 沙眼衣原体对喹诺酮类耐药机制的进展%Update on the mechanism of Chlamydia trachomatis resistance to quinolones

    Institute of Scientific and Technical Information of China (English)

    杨晓静; 刘全忠

    2009-01-01

    Quinolones are commonly used to treat Chlamydiatra chomatis inection in clinic at present.However,the resistance of Chlamydia trachomatis to quinolones has been increasingly reported.It has becn shown that the resistance is related to point mutations in the quinolone-resistance-determinning region of DNA gyrase gene and topoisomerase IV subunit genes.These mutations are located most commonly at Ser-83,less frequently at Asp-87.There are also some other mechanisms underlying the resistance.Further studies are needed for the elucidation of exact mechanism of Chlamydia trachomatis resistance to quinolones.%喹诺酮类药物目前在临床上常用于治疗沙眼衣原体感染,但近年来有关沙眼衣原体对其耐药的报道不断出现.研究发现,喹诺酮类耐药的产生与DNA回旋酶和拓扑异构酶Ⅳ亚单位基因的喹诺酮耐药决定区域的点突变有关.最常见的突变位于Ser-83,少数情况下位于Asp-87,还有一些其他可能的耐药机制.沙眼衣原体对喹诺酮类耐药的确切机制尚待进一步研究.

  9. [Surveillance of Antimicrobial Resistant Esherichia coli by Rectal Swab Method--Annual Change of Prevalence of Quinolone-resistant and ESBL Producing Strains from 2009 to 2013].

    Science.gov (United States)

    Nasu, Yoshitsugu; Sako, Shinichi; Yano, Tomofumi; Kosaka, Noriko

    2015-09-01

    Although most of commonly used antimicrobial agents had been susceptible to Esherichia coli, recently there are a lot of reports concerning about community-acquired infection caused by resistant E. coli. The aim of this study is to define the prevalence of resistant E. coli in normal flora colonization by the rectal swab method. From June 2009 to December 2013, 251 male patients (50-85 year-old, median 68) planned to transrectal prostate biopsy participated in this study. Stools stuck on the glove at the digital examination were provided for culture specimen. Identification of E. coli and determination of MIC was performed by MicroScan WalkAway40plus (Siemens). Isolated E. coli were deemed quinolone-resistant strains when their MIC of levofloxacine was 4 μg/mL or above according to the breakpoint MIC by the CLSI criteria. ESBL producing ability was determined by the double disk method used by CVA contained ESBL definition disc (Eikenkagaku). Of the 251 study patients, 224 patients had positive cultures of E. coli. Twenty-four patients had quinolone-resistant strains and 9 patients had ESBL producing strains. The prevalence of quinolone-resistant strains in 2009, 2010, 2011, 2012 and 2013 were 5.9% (2 out of 34 strains), 13.5% (5 out of 37 strains), 12.5% (4 out of 32 strains), 9.0% (6 out of 67) and 13.0% (7 out of 54 strains), respectively. The prevalence of ESBL producing strains in 2009, 2010, 2011, 2012 and 2013 were 0% (0 out of 34 strains), 5.4% (2 out of 37 strains), 3.1% (1 out of 32 strains), 3.0% (2 out of 67 strains) and 7.4% (4 out of 54 strains), respectively. In 2013, the prevalence of antimicrobial resistant E. coli, both quinolone-resistant and ESBL producing strains, were increasing. We have to pay a close attention to the increase of resistant E. coli.

  10. Mechanisms of quinolone resistance in Escherichia coli: characterization of nfxB and cfxB, two mutant resistance loci decreasing norfloxacin accumulation.

    OpenAIRE

    Hooper, D C; Wolfson, J S; Souza, K S; Ng, E Y; McHugh, G L; Swartz, M N

    1989-01-01

    Two genetic loci selected for norfloxacin (nfxB) and ciprofloxacin (cfxB) resistance were characterized. Both mutations have previously been shown to confer pleiotropic resistance to quinolones, chloramphenicol, and tetracycline and to decrease expression of porin outer-membrane protein OmpF. nfxB was shown to map at about 19 min and thus to be genetically distinct from ompF (21 min), and cfxB was shown to be very closely linked to marA (34 min). cfxB was dominant over cfxB+ in merodiploids, ...

  11. Occurrence of fluoroquinolones and fluoroquinolone-resistance genes in the aquatic environment.

    Science.gov (United States)

    Adachi, Fumie; Yamamoto, Atsushi; Takakura, Koh-Ichi; Kawahara, Ryuji

    2013-02-01

    Fluoroquinolones (FQs) have been detected in aquatic environments in several countries. Long-term exposure to low levels of antimicrobial agents provides selective pressure, which might alter the sensitivity of bacteria to antimicrobial agents in the environment. Here, we examined FQ levels and the resistance of Escherichia coli (E. coli) to FQs by phenotyping and genotyping. In the aquatic environment in Osaka, Japan, ciprofloxacin, enoxacin, enfloxacin, lomefloxacin, norfloxacin, and ofloxacin were detected in concentrations ranging from 0.1 to 570 ng L(-1). FQ-resistant E. coli were also found. Although no obvious correlation was detected between the concentration of FQs and the presence of FQ-resistant E. coli, FQ-resistant E. coli were detected in samples along with FQs, particularly ciprofloxacin and ofloxacin. Most FQ-resistant E. coli carried mutations in gyrA, parC, and parE in quinolone resistance-determining regions. No mutations in gyrB were detected in any isolates. Amino acid changes in these isolates were quite similar to those in clinical isolates. Six strains carried the plasmid-mediated quinolone resistance determinant qnrS1 and expressed low susceptibility to ciprofloxacin and nalidixic acid: the minimum inhibitory concentrations ranged from 0.25 μg mL(-1) for ciprofloxacin, and from 8 to 16 μg mL(-1) for nalidixic acid. This finding confirmed that plasmids containing qnr genes themselves did not confer full resistance to quinolones. Because plasmids are responsible for much of the horizontal gene transfer, these genes may transfer and spread in the environment. To our knowledge, this is the first report of plasmid-mediated quinolone resistance determinant qnrS1 in the aquatic environment, and this investigation provides baseline data on antimicrobial resistance profiles in the Osaka area.

  12. Emergence of quinolone-resistant strains in Streptococcus pneumoniae isolated from paediatric patients since the approval of oral fluoroquinolones in Japan.

    Science.gov (United States)

    Takeuchi, Noriko; Ohkusu, Misako; Hoshino, Tadashi; Naito, Sachiko; Takaya, Akiko; Yamamoto, Tomoko; Ishiwada, Naruhiko

    2017-04-01

    Tosufloxacin (TFLX) is a fluoroquinolone antimicrobial agent. TFLX granules for children were initially released in Japan in 2010 to treat otitis media and pneumonia caused by drug-resistant bacteria, e.g. penicillin-resistant Streptococcus pneumoniae and beta-lactamase-negative, ampicillin-resistant Haemophilus influenzae. The evolution of bacterial resistance since TFLX approval is not known. To clarify the influence of quinolones administered to children since their approval, we examined the resistance mechanism of TFLX-resistant S. pneumoniae isolated from paediatric patients as well as patient clinical characteristics. TFLX-resistant strains (MIC ≥ 2 mg/L) were detected among clinical isolates of S. pneumoniae derived from children (≤15 years old) between 2010 and 2014. These strains were characterised based on quinolone resistance-determining regions (QRDRs), i.e. gyrA, gyrB, parC, and parE. In addition, the antimicrobial susceptibility, serotype, and multilocus sequence type of strains were determined, pulsed-field gel electrophoresis was performed, and patient clinical characteristics based on medical records were assessed for cases with underling TFLX-resistant strains. Among 1168 S. pneumoniae isolates, two TFLX-resistant strains were detected from respiratory specimens obtained from paediatric patients with frequent exposure to TFLX. Both strains had mutations in the QRDRs of gyrA and parC. One case exhibited gradual changes in the QRDR during the clinical course. This is the first study of quinolone-resistant S. pneumoniae isolated from children, including clinical data, in Japan. These data may help prevent increases in infections of quinolone-resistant S. pneumoniae in children; specifically, the results emphasise the importance of administering fluoroquinolones only in appropriate cases. Copyright © 2017 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  13. Mechanisms of quinolone resistance in Escherichia coli: characterization of nfxB and cfxB, two mutant resistance loci decreasing norfloxacin accumulation.

    Science.gov (United States)

    Hooper, D C; Wolfson, J S; Souza, K S; Ng, E Y; McHugh, G L; Swartz, M N

    1989-03-01

    Two genetic loci selected for norfloxacin (nfxB) and ciprofloxacin (cfxB) resistance were characterized. Both mutations have previously been shown to confer pleiotropic resistance to quinolones, chloramphenicol, and tetracycline and to decrease expression of porin outer-membrane protein OmpF. nfxB was shown to map at about 19 min and thus to be genetically distinct from ompF (21 min), and cfxB was shown to be very closely linked to marA (34 min). cfxB was dominant over cfxB+ in merodiploids, in contrast to other quinolone resistance mutations. The two loci appear to interact functionally, because nfxB was not expressed in the presence of marA::Tn5. Both nfxB and cfxB decreased the expression of ompF up to 50-fold at the posttranscriptional level as determined in strains containing ompF-lacZ operon and protein fusions. Both mutations also decreased norfloxacin accumulation in intact cells. This decrease in accumulation was abolished by energy inhibitors and by removal of the outer membrane. These findings, in conjunction with those of Cohen et al. (S. P. Cohen, D. C. Hooper, J. S. Wolfson, K. S. Souza, L. M. McMurry, and S. B. Levy, Antimicrob. Agents Chemother. 32:1187-1191, 1988), suggest a model for quinolone resistance by decreased permeation in which decreased diffusion through porin channels in the outer membrane interacts with a saturable drug efflux system at the inner membrane.

  14. Prevalence of plasmid-mediated AmpC β-lactamase-producing Escherichia coli and spread of the ST131 clone among extended-spectrum β-lactamase-producing E. coli in Japan.

    Science.gov (United States)

    Matsumura, Yasufumi; Yamamoto, Masaki; Higuchi, Takeshi; Komori, Toshiaki; Tsuboi, Fusayuki; Hayashi, Akihiko; Sugimoto, Yoshihisa; Hotta, Gou; Matsushima, Aki; Nagao, Miki; Takakura, Shunji; Ichiyama, Satoshi

    2012-08-01

    In 2010, a total of 1327 clinical Escherichia coli isolates from five hospitals in the Kyoto and Shiga regions of Japan were analysed by PCR. The prevalences of plasmid-mediated AmpC β-lactamase (pAmpC)-producers, extended-spectrum β-lactamase (ESBL)-producers and co-producers of pAmpC and ESBL were 1.7%, 9.7% and 0.3%, respectively. Less than one-half of the pAmpC-producers were reported to be resistant to third-generation cephalosporins, cephamycins and β-lactam/β-lactam inhibitors using the old 2009 Clinical and Laboratory Standards Institute (CLSI) breakpoints. CMY-2 was the most prevalent pAmpC type (95%), and CTX-M-14 (38%), CTX-M-15 (26%) and CTX-M-27 (19%) were the most prevalent ESBL types. The worldwide O25b-ST131-B2 clone accounted for 11% of pAmpC-producers and 41% of ESBL-producers. The O25b-ST131-B2 clone was characterised by a CTX-M-27- or CTX-M-15-type ESBL and ciprofloxacin-non-susceptibility with quadruple mutations in the quinolone resistance-determining regions (S83L and D87N in GyrA and S80I and E84V in ParC). A significant proportion of pAmpC-producers and the O25b-ST131-B2 clone were found in Japan by a recent regional surveillance programme.

  15. Hydrophilicity of quinolones is not an exclusive factor for decreased activity in efflux-mediated resistant mutants of Staphylococcus aureus.

    Science.gov (United States)

    Takenouchi, T; Tabata, F; Iwata, Y; Hanzawa, H; Sugawara, M; Ohya, S

    1996-08-01

    The elevated expression of the norA gene is responsible for efflux-mediated resistance to quinolones in Staphylococcus aureus (E.Y.W. Ng, M. Trucksis, and D.C. Hooper, Antimicrob. Agents Chemother. 38:1345-1355, 1994). For S. aureus transformed with a plasmid containing the cloned norA gene, SA113(pTUS20) (H. Yoshida, M. Bogaki, S. Nakamura, K. Ubukata, and M. Konno, J. Bacteriol. 172:6942-6949, 1990), and an overexpressed mutant, SA-1199B (G.W. Kaatz, S.M. Seo, and C.A. Ruble, J. Infect. Dis. 163:1080-1086, 1991), the MICs of norfloxacin increased 16 and 64 times compared with its MICs for the recipient and wild-type strains, SA113 and SA-1199, respectively. MICs of CS-940, however, increased only two and eight times, even though these two fluoroquinolones are similarly hydrophilic (apparent logPs of approximately -1). No good correlation was found, among 15 developed and developing quinolones, between the increment ratio in MICs and hydrophobicity (r = 0.61). Analysis of the quantitative structure-activity relationship among 40 fluoroquinolones revealed that the MIC increment ratio was significantly correlated with the bulkiness of the C-7 substituent and bulkiness and hydrophobicity of the C-8 substituent of fluoroquinolones (r = 0.87) and not with its molecular hydrophobicity (r = 0.47). Cellular accumulation of norfloxacin in SA-1199B was significantly lower than that in SA-1199, and it was increased by addition of carbonyl cyanide m-chlorophenyl hydrazone. On the other hand, accumulations of CS-940 in these strains were nearly identical, and they were not affected by addition of the protonophore.

  16. Multiplex PCR Study of Plasmid-Mediated AmpC Beta-Lactamases Genes in Clinical Isolates of Escherichia coli

    Directory of Open Access Journals (Sweden)

    Maryam Dehghani

    2017-02-01

    Full Text Available Background:   AmpC β-lactamases are important cephalosporinases chromosomally encoded in many of Enterobacteriaceae and a few other organisms where they mediate resistance to cephalothin, cefazolin, cefoxitin and penicillins. The six different families of plasmid-mediated AmpC β-lactamases have been described, but no phenotypic test can discriminate among them. AmpC multiplex PCR has been successfully used to discriminate plasmid-mediated ampC specific families in organisms such as Klebsiella pneumonia and Escherichia coli. The aim of this study was to indicate the prevalence of AmpC β-lactamase genes by specifically designed primers through PCR test.Methods:   243 total clinical urine samples were collected, and 227 isolates were identified as Escherichia coli based on standard biochemical tests. Subsequently, the isolates were screened by disc diffusion and combined disc test for β-lactamase production. Resistant isolates were evaluated by PCR for ampC family determination. Results:  Antibiotic resistance pattern were observed as follows: cefepime (%25, ceftazidime (%31, ceftriaxone (%37, cefotaxime (%38. The ratio of isolates was detected as ESBLs and AmpC producers were 34% and 5.2%, respectively. PCR performed on 12 selected isolates via phenotypic tests and the results revealed that among 12 isolates, 11 contained blaCMY-42. Conclusion:  Unfortunately, antibiotic resistance has become an increasingly critical problem in many countries like Iran and occurrence of isolates co-expressing AmpC-β-lactamases and ESBLs can create serious problems in the future. As antibiotic options in the treatment of AmpC β-lactamases and ESBLs producing organisms are extremely limited, molecular screening by laboratories is suggested to reduce the risk of therapeutic defeat.

  17. 铜绿假单胞菌对喹诺酮类药物耐药的分子机制研究%Study on the molecular resistant mechanisms to quinolones in clinical isolates of Pseudomonas aeruginosa

    Institute of Scientific and Technical Information of China (English)

    陈树林; 陈利达; 陈茶; 黄彬; 屈平华; 吴强贵

    2012-01-01

    Objective: To study the molecular resistant mechanism of Pseudomonas aeruginosa to quinolones antibiotics and provide basis for clinical anti — infection therapy. Methods: The chromosome mediated — quinolones resistant genes gyrA, gyrB, parC, parE and plasmid — mediated resistant genes qnrA, qnrB, qnrC, qnrD, qnrS, qepA, oqxA, oqxB and aac(6') -Ib-cr were determinated by PCR. DNA sequencing was used for identification of gyrA and parC. Results: In 98 isolates of Pseudomonas aeruginosa resistant to ciprofloxacin, parE, qnrC and qnrS were not detected. The positive rates of gyrA, gyrB, parC, qnrA, qnrB, qnrD, qepA, aac(6') -1b -cr, oqxA and oqxB were 96.9% , 87.8% , 75.5% , 31.6% , 86.7% , 15. 3% , 11.2% , 53.1 % , 8.2% and 26.5% , respectively. By sequence analysis, 84 strains (85.7% ) had gyrA or parC mutation. 90 strains (91. 8% ) contained plasmid-mediated resistant genes, among them the positive rate of qnrB and aac (6') -Ib-cr were higher than other genes. Conclusion: Chromosome - mediated gene mutation as well as plasmid — mediated qnr, qepA, oqxAB and aac(6') — Ib — cr may be the main mechanisms of Pseudomonas aeruginos resistance to quinolones. qnrB and qnrD were found in Pseudomonas aeruginosa the first time.%目的:研究铜绿假单胞菌对喹诺酮类药物耐药的分子机制,为临床抗感染治疗提供依据.方法:用PCR法检测染色体介导的喹诺酮类耐药基因gyrA、gyrB、parC、parE和质粒介导的喹诺酮类耐药基因qnrA、qnrB、qnrC、qnrD、qnrS、qepA、aac(6’)-Ib-cr、oqxA和oqxB,并对gyrA和parC阳性结果进行测序分析.结果:98株耐环丙沙星的铜绿假单胞菌中未检出parE、qnrC和qnrS基因.gyrA、gyrB和parC的阳性率分别为96.9%、87.8%和75.5%.测序证实84株菌(85.7%)发生gyrA或parC基因突变.90株菌(91.8%)携带质粒介导的耐药基因,qnrA、qnrB、qnrD、qepA、aac(6’)-Ib-cr、oqxA和oqxB的阳性率分别为31.6%、86.7%、15.3%、11.2%、53.1

  18. Preincubation of pneumococci with beta-lactams alone or combined with levofloxacin prevents quinolone-induced resistance without increasing intracellular levels of levofloxacin.

    Science.gov (United States)

    Cottagnoud, Philippe; Johnson, Maggie; Cottagnoud, Marianne; Piddock, Laura

    2005-08-01

    Preincubation of pneumococci with sub-MIC concentrations of ceftriaxone (1/16x MIC), cefotaxime (1/8x MIC), and meropenem (1/4x MIC) alone or combined with levofloxacin (1/8x MIC) over 6 h prevents the emergence of levofloxacin-resistant mutants after 96 h of incubation but does not affect the intracellular accumulation of levofloxacin in two penicillin-resistant pneumococcal strains, suggesting a link between the mechanism of action of beta-lactams and the emergence of quinolone-induced resistance in pneumococci.

  19. Activity of gemifloxacin against quinolone-resistant Streptococcus pneumoniae strains in vitro and in a mouse pneumonia model.

    Science.gov (United States)

    Azoulay-Dupuis, E; Bédos, J P; Mohler, J; Moine, P; Cherbuliez, C; Peytavin, G; Fantin, B; Köhler, T

    2005-03-01

    Gemifloxacin is a novel fluoronaphthyridone quinolone with enhanced in vitro activity against Streptococcus pneumoniae. We investigated the activities of gemifloxacin and trovafloxacin, their abilities to select for resistance in vitro and in vivo, and their efficacies in a mouse model of acute pneumonia. Immunocompetent Swiss mice were infected with 10(5) CFU of a virulent, encapsulated S. pneumoniae strain, P-4241, or its isogenic parC, gyrA, parC gyrA, and efflux mutant derivatives (serotype 3); and leukopenic mice were infected with 10(7) CFU of two poorly virulent clinical strains (serotype 11A) carrying either a parE mutation or a parC, gyrA, and parE triple mutation. The drugs were administered six times every 12 h, starting at either 3 or 18 h postinfection. In vitro, gemifloxacin was the most potent agent against strains with and without acquired resistance to fluoroquinolones. While control mice died within 6 days, gemifloxacin at doses of 25 and 50 mg/kg of body weight was highly effective (survival rates, 90 to 100%) against the wild-type strain and against mutants harboring a single mutation, corresponding to area under the time-versus-serum concentration curve at 24 h (AUC(24))/MIC ratios of 56.5 to 113, and provided a 40% survival rate against a mutant with a double mutation (parC and gyrA). A total AUC(24)/MIC ratio of 28.5 was associated with poor efficacy and the emergence of resistant mutants. Trovafloxacin was as effective as gemifloxacin against mutants with single mutations but did not provide any protection against the mutant with double mutations, despite treatment with a high dose of 200 mg/kg. Gemifloxacin preferentially selected for parC mutants both in vitro and in vivo.

  20. In vitro activity of five quinolones and analysis of the quinolone resistance-determining regions of gyrA, gyrB, parC, and parE in Ureaplasma parvum and Ureaplasma urealyticum clinical isolates from perinatal patients in Japan.

    Science.gov (United States)

    Kawai, Yasuhiro; Nakura, Yukiko; Wakimoto, Tetsu; Nomiyama, Makoto; Tokuda, Tsugumichi; Takayanagi, Toshimitsu; Shiraishi, Jun; Wasada, Kenshi; Kitajima, Hiroyuki; Fujita, Tomio; Nakayama, Masahiro; Mitsuda, Nobuaki; Nakanishi, Isao; Takeuchi, Makoto; Yanagihara, Itaru

    2015-04-01

    Ureaplasma spp. cause several disorders, such as nongonococcal urethritis, miscarriage, and preterm delivery with lung infections in neonates, characterized by pathological chorioamnionitis in the placenta. Although reports on antibiotic resistance in Ureaplasma are on the rise, reports on quinolone-resistant Ureaplasma infections in Japan are limited. The purpose of this study was to determine susceptibilities to five quinolones of Ureaplasma urealyticum and Ureaplasma parvum isolated from perinatal samples in Japan and to characterize the quinolone resistance-determining regions in the gyrA, gyrB, parC, and parE genes. Out of 28 clinical Ureaplasma strains, we isolated 9 with high MICs of quinolones and found a single parC gene mutation, resulting in the change S83L. Among 158 samples, the ParC S83L mutation was found in 37 samples (23.4%), including 1 sample harboring a ParC S83L-GyrB P462S double mutant. Novel mutations of ureaplasmal ParC (S83W and S84P) were independently found in one of the samples. Homology modeling of the ParC S83W mutant suggested steric hindrance of the quinolone-binding pocket (QBP), and de novo prediction of peptide structures revealed that the ParC S84P may break/kink the formation of the α4 helix in the QBP. Further investigations are required to unravel the extent and mechanism of antibiotic resistance of Ureaplasma spp. in Japan.

  1. Evaluation of quinolones for use in detection of determinants of acquired quinolone resistance, including the new transmissible resistance mechanisms qnrA, qnrB, qnrS, and aac(6')Ib-cr, in Escherichia coli and Salmonella enterica and determinations of wild-type distributions.

    Science.gov (United States)

    Cavaco, L M; Aarestrup, F M

    2009-09-01

    Fluoroquinolone resistance in members of the Enterobacteriaceae family is mostly due to mutations in the quinolone resistance-determining regions of the topoisomerase genes. However, transferable genes encoding quinolone resistance have recently been described. The current methods for susceptibility testing are not adapted to the detection of new resistance determinants, which confer low levels of resistance. The aim of this study was to compare the ability of the screening of the different quinolones by disk diffusion assays and MIC determinations to detect fluoroquinolone resistance. Sixty-nine Escherichia coli strains and 62 Salmonella strains, including strains fully susceptible to quinolones, nalidixic acid-resistant strains, strains with resistance to fluoroquinolones (resistant to nalidixic acid), and strains showing low-level resistance to fluoroquinolones conferred by transferable quinolone resistance genes, including qnrA, qnrB, qnrS, and aac(6')Ib-cr, were selected. Disk diffusion assays and MIC determinations by the agar dilution method were performed, according to CLSI standards, with nalidixic acid, flumequine, oxolinic acid, ciprofloxacin, enrofloxacin, marbofloxacin, norfloxacin, ofloxacin, and levofloxacin. The MIC of levofloxacin was determined by an Etest. The results showed a trimodal distribution of the MICs for both E. coli and Salmonella. The MIC distributions for the isolates varied with the compounds tested. Screening for nalidixic acid resistance by MIC testing or disk diffusion assay was not efficient for the detection of some of the isolates carrying qnr and aac(6')Ib-cr. Transferable resistance genes would best be detected by testing for the MIC of ciprofloxacin or norfloxacin, as testing for the MICs of the other compounds would fail to detect isolates carrying aac(6')Ib-cr because the enzyme produced is able to reduce the activities of these two compounds only due to their chemical structures. In conclusion, screening with nalidixic

  2. Occurrence and clonal diversity of multidrug-resistant Klebsiella pneumoniae recovered from inanimate surfaces in Algerian hospital environment: First report of armA, qnrB and aac(6')-Ib-cr genes.

    Science.gov (United States)

    Zenati, Karima; Sahli, Farida; Garcia, Vincent; Bakour, Sofiane; Belhadi, Djellali; Rolain, Jean Marc; Touati, Abdelaziz

    2017-09-01

    The aim of this study is to characterize the molecular support of antibiotic resistance in MDR Klebsiella pneumoniae recovered from inanimate surfaces between March 2012 to February 2014 in three teaching hospitals (Setif, Bejaia and Constantine) in Algeria. Forty-four K. pneumoniae producing ESBL were detected and blaCTX-M-15 and blaCTX-M-3 were detected respectively in 41 and 3 isolates. These K. pneumoniae isolates producing ESBL were also resistant to gentamicin (87%), tobramicin (87%), ciprofloxacin (66%) and ofloxacin (62%). Aminoglycosides resistance genes detected were 16S rRNA methylase (armA), aminoglycoside acetyl-transferase (aac(6')-Ib), aminoglycoside nucleotidyl-transferase (aadA2) and aminoglycoside, phosphoryl-transferase (ant3″Ih-aac(6')-IId). Plasmid-mediated quinolone resistance (PMQR) genes detected were aac(6')-Ib-cr (34 isolates) and qnrB genes in (34 isolates). Multilocus sequence typing (MLST) resulted in 12 different sequence types (STs) regrouped into 5 clonal complexes (CC147, CC17, CC37, CC2 and CC23), one clonal group (CG485) and 4 singletons (ST1426, ST405, ST1308, ST873). Here, we report the detection of the ESBLs encoding gene linked with plasmid-mediated quinolone resistance (PMQR) and aminoglycosides resistance recovered from inanimate surfaces in hospital environment. Copyright © 2017 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.

  3. Laboratory surveillance for prospective plasmid-mediated AmpC beta-lactamases in the Kinki region of Japan.

    Science.gov (United States)

    Yamasaki, Katsutoshi; Komatsu, Masaru; Abe, Noriyuki; Fukuda, Saori; Miyamoto, Yugo; Higuchi, Takeshi; Ono, Tamotsu; Nishio, Hisaaki; Sueyoshi, Noriyuki; Kida, Kaneyuki; Satoh, Kaori; Toyokawa, Masahiro; Nishi, Isao; Sakamoto, Masako; Akagi, Masahiro; Nakai, Isako; Kofuku, Tomomi; Orita, Tamaki; Wada, Yasunao; Jikimoto, Takumi; Kinoshita, Shohiro; Miyamoto, Kazuaki; Hirai, Itaru; Yamamoto, Yoshimasa

    2010-09-01

    Extended-spectrum beta-lactamases, plasmid-mediated AmpC beta-lactamases (PABLs), and plasmid-mediated metallo-beta-lactamases confer resistance to many beta-lactams. In Japan, although several reports exist on the prevalence of extended-spectrum beta-lactamases and metallo-beta-lactamases, the prevalence and characteristics of PABLs remain unknown. To investigate the production of PABLs, a total of 22,869 strains of 4 enterobacterial species, Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, and Proteus mirabilis, were collected during six 6-month periods from 17 clinical laboratories in the Kinki region of Japan. PABLs were detected in 29 (0.13%) of 22,869 isolates by the 3-dimensional test, PCR analysis, and DNA sequencing analysis. PABL-positive isolates were detected among isolates from 13 laboratories. Seventeen of 13,995 (0.12%) E. coli isolates, 8 of 5,970 (0.13%) K. pneumoniae isolates, 3 of 1,722 (0.17%) K. oxytoca isolates, and 1 of 1,182 (0.08%) P. mirabilis isolates were positive for PABLs. Of these 29 PABL-positive strains, 20 (69.0%), 6 (20.7%), 2 (6.9%), and 1 (3.4%) carried the genes for CMY-2, DHA-1, CMY-8, and MOX-1 PABLs, respectively. Pattern analysis of randomly amplified polymorphic DNA and pulsed-field gel electrophoretic analysis revealed that the prevalence of CMY-2-producing E. coli strains was not due to epidemic strains and that 3 DHA-1-producing K. pneumoniae strains were identical, suggesting their clonal relatedness. In conclusion, the DHA-1 PABLs were predominantly present in K. pneumoniae strains, but CMY-2 PABLs were predominantly present in E. coli strains. The present findings will provide significant information to assist in preventing the emergence and further spread of PABL-producing bacteria.

  4. Quinolone pharmacokinetics.

    Science.gov (United States)

    Robson, R A

    1992-12-01

    Fluoroquinolones have broad antibacterial spectra and are active against most Gram-negative and many Gram-positive species. They exhibit excellent oral bioavailability, extensive tissue penetration, low protein binding, and a long elimination half-life. This review compares and contrasts the pharmakonetics of some quinolone antibiotics - especially pefloxacin, ciprofloxacin, enoxacin, norfloxacin, ofloxacin, fleroxacin and lomefloxacin - in terms of their adsorption, distribution, metabolism, elimination, and interactions with other drugs and with food. In addition, the pharmacokinetics of these agents in the elderly and in patients with renal or hepatic impairment is discussed. The fluoroquinolones are established as a major class of antibiotics in the treatment of infections but pharmacokinetics factors should be considered when deciding on the most appropriate of these agents to use in individual patients.

  5. Susceptibility to β-lactams and quinolones of Enterobacteriaceae isolated from urinary tract infections in outpatients

    Science.gov (United States)

    Marchisio, Martín; Porto, Ayelén; Joris, Romina; Rico, Marina; Baroni, María R.; Di Conza, José

    2015-01-01

    Abstract The antibiotic susceptibility profile was evaluated in 71 Enterobacteriaceae isolates obtained from outpatient urine cultures in July 2010 from two health institutions in Santa Fe, Argentina. The highest rates of antibiotic resistance were observed for ampicillin (AMP) (69%), trimethoprim/sulfamethoxazole (TMS) (33%), and ciprofloxacin (CIP) (25%). Meanwhile, 21% of the isolates were resistant to three or more tested antibiotics families. Thirty integron-containing bacteria (42.3%) were detected, and a strong association with TMS resistance was found. Third generation cephalosporin resistance was detected in only one Escherichia coli isolate, and it was characterized as a bla CMY-2 carrier. No plasmid-mediated quinolone resistance (PMQR) was found. Resistance to fluoroquinolone in the isolates was due to alterations in QRDR regions. Two mutations in GyrA (S83L, D87N) and one in ParC (S80I) were observed in all CIP-resistant E. coli. It was determined to be the main phylogenetic groups in E. coli isolates. Minimum Inhibitory Concentration (MIC) values against nalidixic acid (NAL), levofloxacin (LEV), and CIP were determined for 63 uropathogenic E. coli isolates as MIC50 of 4 μg/mL, 0.03125 μg/mL, and 0.03125 μg/mL, respectively, while the MIC90 values of the antibiotics were determined as 1024 μg/mL, 64 μg/mL, and 16 μg/mL, respectively. An association between the phylogenetic groups, A and B1 with fluoroquinolone resistance was observed. These results point to the importance of awareness of the potential risk associated with empirical treatment with both the families of antibiotics. PMID:26691475

  6. Susceptibility to β-lactams and quinolones of Enterobacteriaceae isolated from urinary tract infections in outpatients

    Directory of Open Access Journals (Sweden)

    Martín Marchisio

    2015-01-01

    Full Text Available AbstractThe antibiotic susceptibility profile was evaluated in 71 Enterobacteriaceae isolates obtained from outpatient urine cultures in July 2010 from two health institutions in Santa Fe, Argentina. The highest rates of antibiotic resistance were observed for ampicillin (AMP (69%, trimethoprim/sulfamethoxazole (TMS (33%, and ciprofloxacin (CIP (25%. Meanwhile, 21% of the isolates were resistant to three or more tested antibiotics families. Thirty integron-containing bacteria (42.3% were detected, and a strong association with TMS resistance was found. Third generation cephalosporin resistance was detected in only one Escherichia coli isolate, and it was characterized as a blaCMY-2 carrier. No plasmid-mediated quinolone resistance (PMQR was found. Resistance to fluoroquinolone in the isolates was due to alterations in QRDR regions. Two mutations in GyrA (S83L, D87N and one in ParC (S80I were observed in all CIP-resistant E. coli. It was determined to be the main phylogenetic groups in E. coli isolates. Minimum Inhibitory Concentration (MIC values against nalidixic acid (NAL, levofloxacin (LEV, and CIP were determined for 63 uropathogenic E. coli isolates as MIC50 of 4 μg/mL, 0.03125 μg/mL, and 0.03125 μg/mL, respectively, while the MIC90 values of the antibiotics were determined as 1024 μg/mL, 64 μg/mL, and 16 μg/mL, respectively. An association between the phylogenetic groups, A and B1 with fluoroquinolone resistance was observed. These results point to the importance of awareness of the potential risk associated with empirical treatment with both the families of antibiotics.

  7. Fluoroquinolone-resistance mechanisms and phylogenetic background of clinical Escherichia coli strains isolated in south-east Poland.

    Science.gov (United States)

    Korona-Glowniak, Izabela; Skrzypek, Kinga; Siwiec, Radosław; Wrobel, Andrzej; Malm, Anna

    2016-07-01

    Fluorochinolones are a class of broad-spectrum antimicrobials in the treatment of several infections, including those caused by Escherichia coli. Due to the increasing resistance of bacteria to antimicrobials, an understanding of fluoroquinolone resistance is important for infection control. The aim of this study was to determine susceptibility of clinical E. coli strains to fluoroquinolones and characterize their mechanisms of quinolone resistance. Totally, 79 non-duplicate clinical E. coli isolates included in this study were mainly from skin lesion -36 (45.6%) isolates; 54 (68.4%) isolates were assigned to phylogenetic B2 group. Resistance to ciprofloxacin was found in 20 isolates. In the quinolone resistance-determining region (QRDR) region of gyrA and parC, 4 types of point mutations were detected. Mutations in parC gene were found in all strains with gyrA mutations. Predominance of double mutation in codon 83 and 87 of gyrA (90%) and in codon 80 of parC (90%) was found. Moreover, plasmid-mediated quinolone resistance (PMRQ) determinants (qnrA or qnrB and/or aac(6')-Ib-cr) were present in 5 (25%) out of 20 fluoroquinolone-resistant isolates. Resistance to fluoroquinolones in all of the tested clinical E. coli isolates correlated with point mutations in both gyrA and parC. The majority of fluoroquinolone-resistant strains belonged to D and B2 phylogenetic groups.

  8. Influência do uso de enrofloxacina no desenvolvimento de resistência às quinolonas mediada por plasmídeos em Escherichia coli de vitelos [Selection of plasmid-mediated quinolone resistance in commensal E. coli by the use of enrofloxacin in calves

    DEFF Research Database (Denmark)

    Guerreiro, L.; Couto, N.; Centeno, M.

    ), respectivamente]. A caracterização fenotípica foi realizada por determinação das CIMs por microdiluição e os resultados interpretados segundo a norma M100-S20 (CLSI, 2010) . A caracterização genotípica da RQMP foi determinada através de amplificação por PCR dos genes anteriormente mencionados e posterior...

  9. Influência do uso de enrofloxacina no desenvolvimento de resistência às quinolonas mediada por plasmídeos em Escherichia coli de vitelos [Selection of plasmid-mediated quinolone resistance in commensal E. coli by the use of enrofloxacin in calves

    DEFF Research Database (Denmark)

    Guerreiro, L.; Couto, N.; Centeno, M.

    os genes qnr (A, B, C, D e S), o gene aac(6’)-Ib-cr e o genecodificante da de bomba de efluxo qQep A; e ii) determinar a Concentração Inibitória Mínima (CIM) dos antibióticos ácido nalidíxico AN, ciprofloxacina CIP e levofloxacina LEV, em isolados de E. coli de vitelos previamente isolados após...

  10. Isolation and molecular characterization of multidrug-resistant Gram-negative bacteria from imported flamingos in Japan

    Directory of Open Access Journals (Sweden)

    Fukumoto Yukio

    2009-11-01

    Full Text Available Abstract Imported animals, especially those from developing countries, may constitute a potential hazard to native animals and to public health. In this study, a new flock of lesser flamingos imported from Tanzania to Hiroshima Zoological Park were screened for multidrug-resistant Gram-negative bacteria, integrons and antimicrobial resistance genes. Thirty-seven Gram-negative bacterial isolates were obtained from the flamingos. Seven isolates (18.9% showed multidrug resistance phenotypes, the most common being against: ampicillin, streptomycin, tetracycline, trimethoprim/sulfamethoxazole and nalidixic acid. Molecular analyses identified class 1 and class 2 integrons, β-lactamase-encoding genes, blaTEM-1 and blaCTX-M-2 and the plasmid-mediated quinolone resistance genes, qnrS and qnrB. This study highlights the role of animal importation in the dissemination of multidrug-resistant bacteria, integrons and antimicrobial resistance genes from one country to another.

  11. Expansion of plasmid mediated blaACT-2 among Pseudomonas aeruginosa associated with postoperative infection and its transcriptional response under cephalosporin stress.

    Directory of Open Access Journals (Sweden)

    Birson Ingti, Deepjyoti Paul, Anand Prakash Maurya

    2017-06-01

    Full Text Available Objectives: Organisms harboring multiple plasmid mediated β-lactamases are major concerns in nosocomial infections. Among these plasmid mediated β-lactamases, ACT (EBC family is a clinically important enzyme capable of hydrolyzing broad spectrum cephalosporins. Therefore, the present study was undertaken to determine the prevalence of ACT determinant along with other co-existing β-lactamase genes in P. aeruginosa strains. Methods: A total of 176 Pseudomonas isolates were phenotypically screened for the presence of AmpC β-lactamase by M3DET Method followed by Molecular detection using PCR assay. Transcriptional evaluation of blaACT-2 gene was analyzed by RT-PCR and its transferability was performed by transformation and conjugation. Results: Present study demonstrates the presence of ACT-2 allele among 12 strains of P. aeruginosa. Co-existence of other β-lactamase genes were encountered among ACT-2 harboring strains which includes CTX-M (n=2, SHV (n=3, TEM (n=2, VEB (n=2, OXA-10 (n=1, CIT (n=2 and DHA (n=3. Fingerprinting by REP PCR revealed the isolates harboring ACT-2 to be distinct and these isolates showed high resistance to expanded-spectrum cephalosporins and even to carbapenem group of drugs. This ACT-2 allele was encoded in the plasmid (L/M, FIA, FIB Inc. Group and conjugatively transferable. Transcriptional analysis revealed a significant increase in ACT-2 expression (483 fold when induced by ceftriaxone at 4 µg/ml followed by ceftazidime at 8 µg/ml (31 fold and cefotaxime 4 µg/ml (8 fold. Conclusion: In this study detection of ACT-2 plasmid mediated AmpC β-lactamase along with other β-lactamase genes in clinical isolates of P. aeruginosa represents a serious therapeutic challenge. Therefore, revision in antimicrobial policy is required for effective treatment of patients infected with pathogen expressing this mechanism. J Microbiol Infect Dis 2017; 7(2: 75-82

  12. [Resistance surveillance of Neisseria gonorrhoeae in a hospital in Santa Fe province, Argentina: 1997-2004].

    Science.gov (United States)

    Méndez, E de los A; Morano, S T; Mollerach, A S; Mendosa, M A; Ahumada, C; Pagano, I; Oviedo, C; Galarza, P

    2008-01-01

    Resistance phenotypes characterized by minimum inhibitory concentration, disk diffusion and beta-lactamase production were determined in 434 isolates from patients attending the Sexually Transmitted Disease Service at Dr. José Maria Cullen Hospital in Santa Fe, Argentina. Susceptibility tests to penicillin, tetracycline, ciprofloxacin, espectinomycin, azithromycin and ceftriaxone were performed. Pulsed-field gel electrophoresis was conducted made to on three ciprofloxacin-resistant isolates. Epidemiologically speaking, three interesting events should be highlighted: during 1997, plasmid-mediated high level tetracycline-resistant strains were observed (33.3%); from 2002 to 2004 a significant increase of plasmid-mediated penicillin-resistant strains was registered (9.7% to 34.8%); and in the year 2000 the first two quinolone-resistant strains emerged in the province. In our hospital, the first azithromycin-resistant isolate emerged in 2004. We therefore emphasize the importance of the Clinical Microbiology Laboratory in order to provide information for the empiric treatment of this infection.

  13. Presence of quinolone resistance to qnrB1 genes and blaOXA-48 carbapenemase in clinical isolates of Klebsiella pneumoniae in Spain.

    Science.gov (United States)

    Rodríguez Martínez, J M; Díaz-de Alba, P; Lopez-Cerero; Ruiz-Carrascoso, G; Gomez-Gil, R; Pascual, A

    2014-01-01

    A study is presented on the presence of quinolone resistance qnrB1 genes in clinical isolates belonging to the largest series of infections caused by OXA-48-producing Klebsiella pneumoniae in a single-centre outbreak in Spain. Evidence is also provided, according to in vitro results, that there is a possibility of co-transfer of plasmid harbouring blaOXA-48 with an other plasmid harbouring qnrB1 in presence of low antibiotic concentrations of fluoroquinolones, showing the risk of multi-resistance screening. Copyright © 2013 Elsevier España, S.L.U. y Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

  14. Genetic environments of the transferable plasmid-mediated blaCTX-M-3 gene in Serratia marcescens isolates.

    Science.gov (United States)

    Chu, Pei-Yu; Peng, Chien-Fang

    2014-01-01

    In this study, genetic environments of the transferable plasmid-mediated blaCTX-M-3 gene were characterized among 14 isolates of cefotaxime-resistant Serratia marcescens using PCR and BLAST DNA sequence analysis. A total of 3 types of genetic architectures in the regions surrounding this blaCTX-M-3 gene were identified. Type I architecture was characterized by the presence of a complete insertion sequence of tnpA-ISEcp1, identified as interrupting a reverse IS26 sequence in the upstream region of the blaCTX-M-3 gene. A reverse-directional orf477 fragment was located downstream of the blaCTX-M-3 gene, which was in the same direction of the mucA gene. A common region containing the orf513 element was located upstream of the mucA gene. Moreover, a copy of the 3'-CS2 element was located immediately upstream of the orf513 element. A novel complex class 1 integron was characterized by the presence of the dfrA19 gene, which was flanked by two copies of class 1 integrons. This is the first report to describe the dfrA19 gene within a novel complex class 1 integron in S. marcescens isolates from Taiwan. This novel complex class 1 integron structure was located distantly upstream of the blaCTX-M-3 gene.

  15. 喹诺酮耐药大肠埃希菌尿道感染现状及危险因素分析%Quinolone resistant Escherichia coli isolated from urinary tract infection:clinical status and risk factors

    Institute of Scientific and Technical Information of China (English)

    张安兵

    2012-01-01

    Objective To investigate the quinolone resistant Escherkhia coli infection status and risk factors, and provide a basis for selecting appropriate antibiotics in the clinical practice. Methods This study is a retrospective review from 2010 to 2011. 348 strains Escherichia coli isolated from urine specimens were analysis, using the quinolone susceptible isolates as the control group. The risk factors for the quinolone resistance strains were analyzed. Results Of the 348 E.coli strains isolated from urinary tract infection patient, 58.3% (203)were quinolone resistant. Logistic regression analysis showed three generation cephalosporins and quinolones drug use, urinary drainage and bacterium producing extra-broad spectrum beta-lactamase were the independent risk factors for ciprofloxacin resistance of E.coli strains isolated from urinary tract infection patients. Conclusion The epidemic of quinolone resistant Escherichia coli isolated from urine specimens were extremely serious. The drug resistance of the quinolone resistant isolates was strong. The patients infected with quinolone resistant strains had high medical cost and longer average length of stay in hospital. The quinolone resistant E.coli infection with multiple independent risk factors, the strengthening of these independent risk factor controls can effectively prevent the spread of quinolone resistant strains infection.%目的 分析喹诺酮耐药大肠埃希菌尿道感染现状及危险因素,为临床合理选用抗生素提供依据.方法 回顾性分析348例大肠埃希菌尿道感染临床现状,以喹诺酮敏感大肠埃希菌为对照菌株,对喹诺酮耐药大肠埃希菌感染危险因素进行分析.结果 348株大肠埃希菌尿道感染中检出喹诺酮耐药菌203株,占58.3%.Logistic回归分析显示三代头孢菌素及喹诺酮类药物使用、尿路引流和细菌产超广谱β-内酰胺酶是喹诺酮耐药大肠埃希菌感染的独立危险因素.结论 尿道感染大肠埃

  16. Antimicrobial resistance of Salmonella spp. isolated from food

    Science.gov (United States)

    Mąka, Łukasz; Popowska, Magdalena

    This review summarizes current data on resistance among Salmonella spp. isolates of food origin from countries in different regions of the world. The mechanisms of resistance to different groups of antimicrobial compounds are also considered. Among strains resistant to quinolones and/or fluoroquinolones the most prevalent mechanism is amino acid substitutions in quinolone resistance-determining region (QRDR) of genes gyrA, parC but mechanism of growing importance is plasmid-mediated quinolone resistance (PMQR) associated with genes qnrA, qnrB, qnrC, qnrD, qnrS but frequency of their detection is different. Resistance to sulfonamides is mostly associated with genes sul1 and sul2, while resistance to trimethoprim is associated with various variants of dhfr ( dfr) genes. Taking into account Salmonella spp. strains isolated from food, resistance to β-lactams is commonly associated with β-lactamases encoding by blaTEM genes. However strains ESBL and AmpC – positive are also detected. Resistance to aminoglicosides is commonly result of enzymatic inactivation. Three types of aminoglycoside modifying enzyme are: acetyltransferases (AAC), adenyltransferases (ANT) and phosphotransferases (APH). Resistance to tetracyclines among Salmonella spp. isolated from food is most commonly associated with active efflux. Among numerous genetic determinants encoding efflux pumps tetA, tetB, tetC, tetD, tetE and tetG are reported predominatingly. One of the most common mechanisms of resistance against chloramphenicol is its inactivation by chloramphenicol acetyltrasferases (CATs), but resistance to this compound can be also mediated by chloramphenicol efflux pumps encoded by the genes cmlA and floR. It is important to monitor resistance of Salmonella isolated from food, because the globalization of trade, leading to the long-distance

  17. 猪源大肠杆菌同一质粒中检测到qnrA和aac(6')-Ib-cr耐药基因%Plasmid-mediated quinolone resistance determinants qnrA1 and qnrA3 in Escherichia coli isolates from pigs containing the aac(6')-Ib-cr gene

    Institute of Scientific and Technical Information of China (English)

    陈祥; 张宁; 张维秋; 李秀; 王彦红; 焦新安

    2014-01-01

    目的 自1998年报道质粒介导的喹诺酮类药物耐药基因(PMQR)qnrA以来,qnrB、qnrC、qnrD、qnrS、oqxAB、qepA和aac(6')-Ib-cr等质粒介导的耐药基因被陆续报道,本文对中国分离的猪源大肠杆菌进行质粒介导的喹诺酮类药物耐药基因分析.方法 在1998-2007年间从中国分离到的198株猪源大肠杆菌中,运用PCR、接合试验、药物敏感性试验、S1-PFGE和Southern blot等方法对其进行研究.结果和结论 2004年从辽宁省分离到的一株猪源大肠杆菌中含有qnrA1和aac(6')-Ib-cr基因,另有2005年从江苏省同一猪场分离到的三株细菌中含有qnrA3和aac(6')-Ib-cr基因.通过S1-PFGE和Southern blot证实qnrA和aac(6')-Ib-cr位于同一质粒上,其共同转移可使环丙沙星MIC值升高32~128倍,并且接合子表现对氨苄西林的耐药性.

  18. Plasmid-mediated extended-spectrum beta-lactamase-producing strains of Enterobacteriaceae isolated from diabetes foot infections in a Brazilian diabetic center

    Directory of Open Access Journals (Sweden)

    R.N. Motta

    2003-04-01

    Full Text Available We bacteriologically analyzed 156 species of Enterobacteriaceae, isolated from 138 patients with community-acquired diabetic foot ulcers, in a prospective study made at a diabetic center and at the Federal University of Ceará, Brazil, from March, 2000, to November, 2001.The samples were cultured using selective media, and identification, susceptibility tests and detection of plasmid-mediated-extended-spectrum-beta-lactamase (ESBL producing strains were made with conventional and automated methods. The most frequently occurring pathogens were K. pneumoniae (21.2%, Morganella morganii (19.9% and E. coli (15.4%. High resistance rates were noted for ampicillin, first generation cephalosporin, trimethoprim/sulfamethoxazole, tetracycline, amoxicillin-clavulanic acid and chloramphenicol. ESBL-producing strains were detected in 6% of the patients. Resistance among gram-negative bacteria has become increasingly common, even in community-acquired infections.

  19. Cloning and nucleotide sequence of Mycobacterium tuberculosis gyrA and gyrB genes and detection of quinolone resistance mutations.

    Science.gov (United States)

    Takiff, H E; Salazar, L; Guerrero, C; Philipp, W; Huang, W M; Kreiswirth, B; Cole, S T; Jacobs, W R; Telenti, A

    1994-04-01

    The emergence of multidrug-resistant strains of Mycobacterium tuberculosis has resulted in increased interest in the fluoroquinolones (FQs) as antituberculosis agents. To investigate the frequency and mechanisms of FQ resistance in M. tuberculosis, we cloned and sequenced the wild-type gyrA and gyrB genes, which encode the A and B subunits of the DNA gyrase, respectively; DNA gyrase is the main target of the FQs. On the basis of the sequence information, we performed DNA amplification for sequencing and single-strand conformation polymorphism analysis to examine the presumed quinolone resistance regions of gyrA and gyrB from reference strains (n = 4) and clinical isolates (n = 55). Mutations in codons of gyrA analogous to those described in other FQ-resistant bacteria were identified in all isolates (n = 14) for which the ciprofloxacin MIC was > 2 micrograms/ml. In addition, we selected ciprofloxacin-resistant mutants of Mycobacterium bovis BCG and M. tuberculosis Erdman and H37ra. Spontaneously resistant mutants developed at a frequency of 1 in 10(7) to 10(8) at ciprofloxacin concentrations of 2 micrograms/ml, but no primary resistant colonies were selected at higher ciprofloxacin concentrations. Replating of those first-step mutants selected for mutants with high levels of resistance which harbored gyrA mutations similar to those found among clinical FQ-resistant isolates. The gyrA and gyrB sequence information will facilitate analysis of the mechanisms of resistance to drugs which target the gyrase and the implementation of rapid strategies for the estimation of FQ susceptibility in clinical M. tuberculosis isolates.

  20. Detection of plasmid-mediated AmpC β-lactamase in Escherichia coli and Klebsiella pneumoniae

    Directory of Open Access Journals (Sweden)

    N O Yilmaz

    2013-01-01

    Full Text Available Background: Detecting plasmid-mediated AmpC (pAmpC β-lactamase-producing organism is important for optimal infection control and providing accurate and effective treatment option for physicians. Objectives: The aim of this study was to investigate the prevalence of pAmpC β-lactamase and compare the results of boronic acid (BA disk test with other phenotypic tests detecting AmpC positive isolates. Materials and Methods: A total of 273 clinical isolates of Klebsiella pneumoniae (n: 82 and Escherichia coli (n: 191 were analysed. The presence of pAmpC β-lactamase was determined by BA disk test, cefoxitin (FOX screening test, modified three dimensional test (M3DT, and multiplex polymerase chain reaction (PCR. Pulsed-field gel electrophoresis was performed to evaluate the genetic similarities between isolates. To detect extended spectrum β-lactamases (ESBL in the presence of AmpC β-lactamase, ESBL confirmation test was carried out with and without BA solution. Results: Of the 273 strains tested, 127 strains were found FOX resistant, 114 were positive by M3DT, 108 were positive in BA disk test, and the multiplex PCR detected 24 pAmpC β-lactamase-positive isolate. The prevalence of AmpC-producing strains was 10.9% in E. coli and 3.6% in K. pneumoniae in the tested population by PCR. CIT and MOX group genes were predominant type in these strains. Conclusion: These results emphasize that clinical laboratories should consider testing the presence of pAmpC enzymes particularly in FOX-resistant isolates, and BA disk test will improve detection of this emerging resistance phenotype.

  1. Prevalence and Resistance Status of Escherichia Coli in Quinolones and Its Prevention and Cure Strategies%大肠埃希氏菌对喹诺酮类药物的耐药现状及防治

    Institute of Scientific and Technical Information of China (English)

    吴勇德; 唐志君

    2014-01-01

    喹诺酮类药物(Quinolones,Qs)是一类合成广谱抗菌药,自20世纪60年代萘啶酸被运用于临床医学以后,同时喹诺酮类药物的耐药问题便接踵而至,这使得喹诺酮类药物成为开发最活跃,更新换代最迅速的药物。由于其具有抗菌谱广,抗菌活性强,与常用抗菌药物无交叉耐药,已成为临床治疗感染性疾病的主要药物之一。然而,随着喹诺酮类药物在人医和兽医临床的广泛、长期、大量盲目滥用,使得其耐药性近年呈蔓延增长趋势,耐药程度越来越重,耐药菌株越来越多。其中,大场杆菌对喹诺酮类药物的耐药性问题是当前国内外研究的热点。本文综述了大肠杆菌对氟喹诺酮类药物耐药现状及特点,并分析了其耐药机制,简要综述了减缓耐药性的一些防治策略。%The Quinolones is a kind of synthetic wide table antimicrobial, Dixiben was applied to clinic medicine since the sixties of the 20th century the question of resistance of Quinolones appeared at the same time that made Quinolones become and develop the most active, update the fastest medicine. Because it has antibacterial wide tables, the antibacterial activity is strong and have not been cross resistance with daily antibacterial medicines, have become one of the clinical main medicines to treat the infective disease. However, as the Quinolones abuse in people and veterinarian's medicine and clinical y extensively and long-termly and in a large amount led to bacterias resistance to quinolones show a tendency to spread and increase in recent years, resistance degree to be more and more heavy , resistance of strains are more and more many. Quinolone resistance in Escherichia coli is a focus studied both at home and abroad at present . The review focuses on prevalence and resistance status of E.coli in Quinolones, the mechanism of Quinolones resistance in E.coli and provides some prevention and cure strategies

  2. High prevalence and variability of CTX-M-15-producing and fluoroquinolone-resistant Escherichia coli observed in stray dogs in rural Angola.

    Science.gov (United States)

    Albrechtova, Katerina; Kubelova, Michaela; Mazancova, Jana; Dolejska, Monika; Literak, Ivan; Cizek, Alois

    2014-08-01

    Antimicrobial resistance (AMR) represents a serious problem globally, but it is especially pronounced in the tropics, where pressure of infectious diseases is high. We examined resistance in Escherichia coli colonizing gastrointestinal tracts of 17 dogs which have never received antimicrobial treatment, living in central rural Angola. Emphasis was placed on extended-spectrum beta-lactamases (ESBL) and plasmid-mediated quinolone resistance (PMQR). Resistance-carrying plasmids were characterized in size, group of incompatibility and ability to conjugate. Isolates were compared by their pulsed-field gel electrophoresis (PFGE) profiles. Detailed description of 19 E. coli isolates with either ESBL or PMQR genes carried on multiresistant plasmids of different groups of incompatibility indicates that dogs, despite never being treated by antibiotics, are important reservoirs and transmitters of AMR in the study area.

  3. Dysglycemia associated with quinolones.

    Science.gov (United States)

    El Ghandour, Sarah; Azar, Sami T

    2015-06-01

    Antimicrobial therapy is well known to be associated with fluctuations of blood glucose levels. This review aims at exploring the association between glycemic fluctuations and antibiotics mainly focusing on quinolones. Quinolones are associated with hypoglycemia and hyperglycemia. Several mechanism are proposed to explain this causality.

  4. 尿道感染大肠埃希菌对喹诺酮耐药性及相关因素分析%Drug Resistance and Risk Factors Analysis of Escherichia Coli Isolated from Urinary Tract Infection to Quinolone

    Institute of Scientific and Technical Information of China (English)

    张昭勇; 张吉才; 杜毅

    2013-01-01

    Objective To investigate the drug resistance and risk factors of Escherichia coli isolated from urinary tract infection (UTI) to quinolone. Methods Drug resistance of 705 strains of Escherichia coli isolated from 749 urine specimens of UTI from 2010 to 2011 in our hospital were detected and divided into the resistance group and the sensitive group according to sensitiveness to quinolone, and the risk factors of the quinolone resistance strains were analyzed. Results In 705 strains isolates E. coli, there were 474 strains (67. 2% ) of quinolone resistance in the resistance group, 231 strains (32. 8% ) of quinolone sensitiveness in the sensitive group and there was no carbapenem resistant strain. The differences in resistance rates of amoxicillin/clavulanic acid, cefotaxime, ceftazidime, aztreonam, piperacillin, amikacin, bactrim, gentamicin and cefepime of the two groups were statistically significant (P<0. 05) . Logistic regression analysis showed that the proportion of female patients, drug use of tert-cephalosporins and quinolones, urinary drainage and bacterium producing extended spectrum β lactamases (ESBLS) were independent risk factors of quinolone resistance E. coli. The differences in hospital stay and cost of the two groups were statistically significant (P<0. 05). Conclusion The detection rate of quinolone resistance escherichia coli isolated from UIT is high. The emergence of resistant strains is related to antibiotic application, invasive handling and bacterial variation. To strengthen the independent risk factors regulation can effectively prevent and control spread of infection.%目的 探讨尿道感染(urinary tract infection,UIT)大肠埃希菌对喹诺酮耐药性及其相关因素.方法 对我院2010-2011年749例UIT尿液标本中分离的705株大肠埃希菌的耐药性进行检测,以对喹诺酮敏感与否分为耐药株组和敏感株组,分析耐药株感染的相关因素.结果 705株大肠埃希菌中对喹诺酮耐药474株(67.2

  5. Detection and analysis of plasmid-mediated carbapenem-hydrolyzing enzyme KPC-2 in carbapenem-resistant Escherichia coli%大肠埃希菌质粒型碳青霉烯酶KPC-2检测和分析

    Institute of Scientific and Technical Information of China (English)

    蒯守刚; 邵海枫; 王卫萍; 史利宁; 张小卫; 范明

    2009-01-01

    Objective To study molecular epidemiology and carbapenem-resistance mechanism of four Escherichia coli strains isolated from general surgery wards. Methods Antibiotic susceptibility was carried out by K-B gar diffusion and agar dilution methods. Carbapenemases were screened by three dimensional test and EDTA-Na_2-disk synergy test. Pulsed-field gel electropboresis (PFGE) was performed to analyze molecular epidemiology of isolates. Plasmid was extracted by using an alkalinelysis technique. Conjunction experiment, transformation assay, specific PCR and DNA sequencing were performed to confirm carbapenemase genotype and its transmission mechanism Results Four Escherichia coli isolates were resistant to most antimicrobials including carbapenem. PFGE showed that the four isolates belong to four different clonal strains. Specific PCR and DNA sequence analysis identified that carbapenem resistance in four clinical isolates was mediated by KPC-2 encoded on an approximately 56 000 bp plasmid, and this plasmid did not harbor aminoglycosides and fluorquinolones resistant genes. Conclusion Four Escherichia coli isolates with carbapenem resistance are obtained from our hospital, and KPC-2 plasmid is main cause of carbapenem resistance in these isolates.%目的 研究普外科病区出现的4株碳青霉烯类药物耐药大肠埃希菌的分子流行病学特征及耐药机制.方法 用K-B纸片法和琼脂稀释法进行药物敏感试验,三维酶抑制试验和EDTA-Na_2协同试验分析酶的性质,通过脉冲场琼脂糖凝胶电泳(PFGE)分析耐药株的分子流行病学特征,特异性PCR及序列分析、接合试验、碱裂解法提取质粒和质粒转化试验研究碳青霉烯耐药的分子机制.结果 4株大肠埃希菌对包括碳青霉烯在内的多种抗菌药物广泛耐药,PFGE显示4株分离株属于不同的克隆型,对碳青霉烯类药物的耐药主要由相对分子质量约56 000的质粒携带的KPC-2基因介导,转化试验显示对氨基

  6. 一株同时携带质粒介导KPC-2、DHA-1基因对碳青霉烯类药物耐药的产气肠杆菌%A clinical isolate of carbapenem-resistant Enterobacter aerogen with plasmid-mediated KPC-2 and DHA-1 ;genes

    Institute of Scientific and Technical Information of China (English)

    蒯守刚; 王卫萍; 裴豪; 范明; 刘君; 周希科; 尚忠波; 邵海枫

    2014-01-01

    Objective To investigate the resistance and transmission mechanisms of a clinical isolate of carbapenem-resistant Enterobacter aerogen.Methods The minimal inhibition concentrations (MIC)of antimicrobial agents were determined by agar dilution method,and plasmid conjugation experiment,plasmid extraction and DNA molecular hybridization, isoelectric focusing electrophoresis (IEF ), polymerase chain reaction (PCR ), DNA sequencing and outer-membrane protein analysis were used for analyzing the resistant gene and transmission mechanism. Results IEF showed that there were 3 bands of beta-lactamases with isoelectric point (pI)of 5.4,6.7 and 7.8 in the clinical isolate of carbapenem-resistant Enterobacter aerogen.These 3 bands of beta-lactamases were confirmed to be TEM-1 (pI 5.4),KPC-2(pI 6.7)and DHA-1 (pI 7.8)by PCR amplification and DNA sequencing,and 2 of them (pIs of 6.7 and 7.8)were found that they can be transferred by plasmid conjugantion experiment.KPC-2 and DHA-1 genes were located on an about 56 kb plasmid by plasmid conjugation experiment,plasmid extraction and DNA molecular hybridization.Outer-membrane protein electrophoresis analysis revealed that a 41 000 outer-membrane protein was absent in the clinical isolate of carbapenem-resistant Enterobacter aerogen comparing with clinical wild-type Enterobacter aerogen.Conclusions The clinical isolate of Enterobacter aerogen resistant to carbapenem produces a plasmid-mediaed carbapemase KPC-2 which belongs to Group 2f,Class A beta-lactamase.DHA-1 enzyme with outer-membrane protein absence may be related with the resistant mechanism of carbapenem-resistance in the isolate of Enterobacter aerogen.%目的研究一株临床分离的碳青霉烯类药物耐药产气肠杆菌的耐药机制和耐药基因传播机制。方法采用琼脂稀释法检测菌株对抗菌药物的最低抑菌浓度(MIC),采用质粒接合试验、质粒提取、DNA分子杂交、等电聚焦电泳(IEF)、聚合酶链反应(PCR)

  7. Study on plasmid-mediated extended spectrum β-lactamases and their resistance phenotypes in Shigella%质粒介导的志贺菌产超广谱β内酰胺酶及其耐药基因型

    Institute of Scientific and Technical Information of China (English)

    苑广盈; 边锋芝; 朱健美; 郑秀峰; 张延芳; 张丽

    2008-01-01

    Objective To discuss the characteristics of extended-spectrum beta-lactamases(ESBLs)-producing Shigella and the relation between them and drug-resistance plasmid. Methods The suspicious ESBLs-producing isolates were screened by K-B disc diffusion method, and the ESBLs-producing strains were confirmed by confirmatory test recommended by the National Committee for Clinical Laboratory Standards. Furthermore, the partial blageneof these isolates were detected by PCR using universal primers for TEM, SHV, CTX-M-1 group, CTX-M-2 group and CTX-M-9 group, respectively. The entire blaCTX-M-9 and blaTEM were amplified by PCR using the primers outside the open reading frame (ORF) of these β-1actamases and products were directly sequenced. The conjugation experiment was performed to determine whether the resistance was transferable. Minimal inhibitory concentration (MIC) was detected with double agar dilution method. Results Of the 275 isolates, 12 strains were identified as ESBLs producers. Among them, 8 strains were CTX-M-14 carriers and 4 strains were CTX-M-3 carriers. All ESBLs-producing isolates are positive for plasmid conjugative transfer test. The transconjugants are only resistance to betalactams. Conclusions High resistance to beta-laetams in Shigella is caused by production of ESBLs in the local area. The ESBLs-produeing isolates can transfer the drug resistance through lateral transfer of plasmid.%目的 探讨产生超广谱β内酰胺酶(ESBLs)志贺菌的特性及与耐药质粒的关系.方法 用K-B法做药敏试验并筛选可疑产ESBLs志贺菌株;ESBLs表型确证试验检测可疑产ESBIs志贺菌;采用TEM、SHV、CTX-M-1组、CTX-M-2组、CTX-M-9组β内酰胺酶通用引物进行PCR检测,TEM、CTX-M-9组全编码基因引物进行PCR测定,对扩增产物进行DNA序列分析;对产ESBLs志贺菌进行接合传递试验,供体菌和接合子用稀释法进行MIC测定.结果 在275株志贺菌中有12株为产ESBLs志贺菌,其中8株

  8. 儿童呼吸道感染肺炎克雷伯菌质粒介导产AmpC酶的耐药性及基因型研究%Detection of drug resistance due to the plasmid-mediated AmpC β-lactamase and genotype analysis in Klebsiella pneumoniae resulting in respiratory infectious in children

    Institute of Scientific and Technical Information of China (English)

    林平

    2011-01-01

    目的 探讨小儿呼吸道感染肺炎克雷伯菌AmpC酶的产生、AmpC酶的耐药基因型及对常用抗菌药物的耐药特征,为临床治疗提供选药参考.方法 采用VITEK-60型全自动细菌鉴定仪鉴定细菌,按CLSI推荐的确证试验检测ESBLs和K-B纸片法测定药敏结果;采用头孢西丁纸片扩散法筛选疑产AmpC酶阳性菌株,并通过酶粗提物头孢西丁三维试验、接合试验、PCR测序等实验分析该菌株的基因型.结果 135株肺炎克雷伯菌ESBLs和AmpC酶总检出率分别为30.37%和15.56%,其中,单产AmpC酶、同产AmpC酶+ESBLs、单产ESBLs检出率分别为8.15%、7.41%和22.96%;AmpC酶阳性菌株的耐药基因型:19株为DHA-1型,2株为ACT-1型.产酶株的耐药性明显高于非产酶株,耐药现象在同产AmpC酶和ESBLs菌株中更为严重,产与非产AmpC酶(和)ESBLs菌株对亚胺培南的敏感率几乎达100%.结论 台州地区小儿呼吸道感染肺炎克雷伯菌产AmpC酶和ESBLs菌株检出率较高,AmpC酶以DHA-1基因型为主.产AmpC酶和ESBLs的菌株呈高度耐药,限制β内酰胺类抗菌药物的应用是减少产酶株流行的重要措施.%Objective To investigate the production and AmpC β-lactamase in Klebsiella (K.)pneumoniae resulting in respiratory infections in children,AmpC β-Lactamase genotypic resistance and typical resistance to common antibiotics so as to provide some references for selecting drugs in clinical treatment.Method Microbiological identification was performed with the VITEK 60 System,extended spectrum β lactamases (ESBLs) were detected in accordance with the confirmatory test recommended by Clinical and Laboratory Standards Institute (CLSI) and drug sensitivity was determined with Kirby-Bauer method.Suspected positive strains of AmpC β-lactamase were screened with cefoxitin disk diffusion.The genotypes were analyzed by cefoxitin three-dimensional test,conjugation test and PCR sequencing.Result Of the 135 isolates,30

  9. Mechanism of Quinolone Resistance and Its Research Progress%喹诺酮类药物的作用机制耐药机制及研究进展

    Institute of Scientific and Technical Information of China (English)

    刘杨; 欧宁

    2014-01-01

    Quinolones are broad spectrum antibiotics for clinical infections, by binding on topoisomerases to prevent DNA replication. But the problems of drug resistance increase seriously in recent years. This arti-cle reviews the mechanism of quinolone resistance and its research progress.%喹诺酮类药物主要作用于DNA拓扑异构酶,阻碍DNA复制,发挥广谱抗菌作用。但该类药物的耐药问题日益严重,耐药菌株频现。本文综述喹诺酮类药物的耐药机制及其研究进展。

  10. Detection of plasmid-mediated Carbapenem-hydrolyzing β-lactamaseKPC-2 in a strain of Carbapenem-resistant C.freundii%碳青酶烯类抗生素耐药弗劳地枸橼JH酸杆菌KPC-2基因的检测

    Institute of Scientific and Technical Information of China (English)

    汪安勇; 王中新; 沈继录

    2012-01-01

    Objective To investigate the mechanism of Carbapenem resistance in C. Freudii. Methods Antibiotic susceptibilities were determined by agar dilution method. Conjugation experiments were carried out in mixed broth cultures. Plasmid DNA preparations were obtained by using an alkalinelysis technique and were digested by various endonucleases; The crude β-lactamase extracts of C. Freudii and E. Coli transconjugant were subjected to analytical isoelectric focusing( IEF )Specific PCR amplification and DNA sequence analysis were performed to confirm the β-lactamse type. Results The C. Freundii isolate showed resistance against Carbapenemes. The MICs of imipen-em and meropenem were both 64 mg · L-1 . The isolate was also resistant against penicillins, cephalosorins, cefoxitins, aztreonam, quinolo-nes,and aminoglycosides. The conjugant results showed the antibiotics can transfer by plasmid. Isoelectric focusing demonstrated two β-lactamases with the isoelectric points of 5. 0 and 7. 5 in conjugant. Specific PCR amplification and DNA sequence analysis show ed that the C. Freudii produce the gene of KPC-2. Coclusion the product of KPC-2 Carbapenem was the first and foremost dues of Carbapenem-risitance and it can transfer by plasmid.%目的 研究弗劳地枸橼酸杆菌对碳青霉烯类抗生素的耐药机制.方法 采用琼脂对倍稀释法检测弗劳地枸橼酸杆菌对亚胺培南和美罗培南以及其他常见药物的最低抑菌浓度(MIC).等电聚集电泳分析其β-内酰胺酶类型,聚合酶链反应(PCR)和DNA序列分析检测β-内酰胺酶基因型,接合试验分析其耐药质粒传递情况.结果 弗劳地枸橼酸杆菌对亚胺培南和美罗培南的MIC均为64 mg·L-1,对青霉素类、头孢菌素类、头孢西丁、氨曲南和氨基糖苷类均耐药.转移接合结果显示对亚胺培南和美罗培南的耐药性可以通过质粒转移.等电聚焦电泳结果显示转移接合子具有等电点(PI)约为5.0、7.5的2种β-内酰

  11. Study on the drug-resistance mechanism of plasmid-mediated KPC-2 carbapenemase possessing Klebsiella pneumoniae isolated from children%质粒介导KPC-2型碳青霉烯酶肺炎克雷伯菌儿童分离株耐药基因研究

    Institute of Scientific and Technical Information of China (English)

    刘洋; 李方去; 蒋伟燕; 杨锦红; 李向阳

    2012-01-01

    目的 研究碳青霉烯类耐药肺炎克雷伯菌临床儿童分离株的耐药特点及分子流行病学特征.方法 收集温州医学院附属第二医院2010年7月-2011年6月从儿童标本中分离的耐碳青霉烯类肺炎克雷伯菌12株,所有菌株为非重复菌株,菌种鉴定采用全自动微生物分析仪.改良的Hodge试验筛选产碳青霉烯酶阳性菌株,采用PCR法检测KPC、IMP、bla(s)、VIM、SPM和整合酶基因,测序确定基因型.对菌株进行质粒结合试验、质粒消除试验检测质粒的转移性.脉冲场凝胶电泳(PFGE)分析耐药菌株的同源性.结果 12株耐碳青霉烯类肺炎克雷伯菌对庆大霉素、妥布霉素、阿米卡星、环丙沙星、左氧氟沙星、复方磺胺甲噁唑的敏感率分别为8.3%、41.7%、58.3%、8.3%、8.3%、33.3%;12株菌均携带有KPC-2基因,且同时携带有TEM-1和SHV型β-内酰胺酶基因,其中SHV-11-like和SHV-1 2-like各6株;11株携带CTX-M型基因,其中4株为CTX-M-14-like基因,6株CTX-M-15-like基因;2株携带有OXA-10型基因,1株携带有PER-1基因.未检出NDM-1、GIM、SPM、SIM、VIM型碳青霉烯酶基因.12株均为Ⅰ类整合酶基因(int1)阳性.2株通过接合试验把质粒传递给受体菌EC600.所有接合子blaTEM-1基因阳性、超广谱β-内酰胺酶(ESBL)基因阳性及对亚胺培南、庆大霉素、阿米卡星、妥布霉素和头孢噻肟耐药,接合子ESBL基因型与供菌一致.2株菌经质粒消除后对亚胺培南的MIC值均有较大程度降低,消除后KPC-2基因扩增为阴性.12株KPC-2基因阳性菌株经PFGE分成5个基因型,主要为B型和C型.结论 KPC-2型碳青霉烯酶基因已经在儿童肺炎克雷伯菌中播散,常伴随携带多种类型的ESBL基因和Ⅰ类整合酶基因,部分耐药基因可通过质粒播散.%Objective To investigate molecular epidemiology and antimicrobial susceptibility of carbapenem-resistant strains of Klebsiella pneumoniae isolated from

  12. Antibacterial action of quinolones: from target to network.

    Science.gov (United States)

    Cheng, Guyue; Hao, Haihong; Dai, Menghong; Liu, Zhenli; Yuan, Zonghui

    2013-08-01

    Quinolones are widely used broad-spectrum antibacterials with incomplete elucidated mechanism of action. Here, molecular basis for the antibacterial action of quinolones, from target to network, is fully discussed and updated. Quinolones trap DNA gyrase or topoisomerase IV to form reversible drug-enzyme-DNA cleavage complexes, resulting in bacteriostasis. Cell death arises from chromosome fragmentation in protein synthesis-dependent or -independent pathways according to distinguished quinolone structures. In the former pathway, irreversible oxidative DNA damage caused by reactive oxygen species kills bacteria eventually. Toxin-antitoxin mazEF is triggered as an additional lethal action. Bacteria survive and develop resistance by SOS and other stress responses. Enlarged knowledges of quinolone actions and bacterial response will provide new targets for drug design and approaches to prevent bacterial resistance.

  13. Emerging quinolones resistant transfer genes among gram-negative bacteria, isolated from faeces of HIV/AIDS patients attending some Clinics and Hospitals in the City of Benin, Edo State, Nigeria

    Directory of Open Access Journals (Sweden)

    Enabulele IO

    2006-12-01

    Full Text Available A survey of 1431 gram-negative bacilli from June 2001 to September 2005 were obtained from the faeces of 920 HIV/AIDS patients attending some Clinics and Hospitals in Benin City, Nigeria, were screened for quinolones resistance gene. The HIV/AIDS patients CD4 cells range was ≤14/mm3 ≥800/mm3 of blood. Out of the 1431 isolates, 343 (23.9% were resistance to quinolones with a MIC ≥4μg/ml for norfloxacin, ciprofloxacin and pefloxacin while a MIC of ≥32 µg/ml for nalidixic acid. The screened isolates include Pseudomonas aeruginosa 64(18.7%, E coli 92(26.8%, Klebsiella pneumoniae 53(15.4%, Salmonella typhi 39(11.4%, Shigella dysenteriae 36(10.5%, Proteus mirabilis 34(9.9% and Serratia marcescens 25(7.3%. The average resistance of the isolates to the various quinolones ranged from 42.7% to 66.7%. Klebsiella were the most resistant isolates with a mean resistance of 66.7% while Proteus were the less resistant isolates with a mean resistance of 42.7%. Most isolates were resistant to Nalidixic acid followed by norfloxacin while the less resistant were to the pefloxacin. The frequency of qnr genes transfer to EJRifr as recipient ranged from 2 x 10-2 to 6 x 10-6 with an average of 2 plasmids per cell. The molecular weight of the plasmids ranged from <2.9kbp to <5.5 kbp. This indicated that plasmids allowed the movement of genetic materials including qnr resistant genes between bacteria species and genera in Benin City, Nigeria.

  14. Cepas de Campylobacter jejuni resistentes a quinolonas aisladas de humanos, gallinas y pollos Quinolone resistant Campylobacter jejuni strains isolated from humans and from poultry

    Directory of Open Access Journals (Sweden)

    Rodolfo Notario

    2011-08-01

    Full Text Available Se compararon 8 aislamientos de Campylobacter jejuni provenientes de humanos con enfermedad diarreica aguda, con 23 aislamientos de cloaca de gallinas y pollos obtenidos de zonas próximas a la ciudad de Rosario, todos resistentes a la ciprofloxacina. Las muestras se sembraron en agar selectivo y se incubaron en microaerofilia a 42 °C. Las colonias se identificaron con el método tradicional. Los aislamientos se conservaron a -70 °C en caldo cerebro corazón con 17% v/v de glicerina. La clonalidad se determinó por RAPD-PCR, utilizando el primer 1254 (Stern NJ. Se interpretaron los aislamientos como clones distintos cuando diferían en una banda de amplificación. Se obtuvieron 5 clones diferentes. Los patrones I, II y V fueron aislados en criaderos industriales de pollos y en humanos (el II también en un establecimiento de gallinas ponedoras de huevos. En un gallinero familiar se obtuvo el patrón I. El patrón III sólo se obtuvo de humanos. El patrón IV se halló en uno de los criaderos pero no en humanos. Se pudo determinar que 93.5% de las cepas se aislaron tanto de animales como de humanos, por lo que se considera posible que la colonización de criaderos con cepas resistentes a los antimicrobianos pudiera ser el origen de la infección de humanos.Eight quinolone resistant Campylobacter jejuni strains isolated from humans with diarrheal disease were compared with 23 isolates from chicken and from laying hens. Samples were cultured on selective agar in microaerophilia, identified by conventional tests, and conserved in 17% glycerol at -70 °C. Clones were determined by RAPD-PCR employing the 1254 primer (Stern NJ. Five patterns were obtained. Patterns I, II, and V were found in both poultry and human isolates. Pattern I was obtained from poultry in a domestic henhouse. Pattern III was only obtained from humans whereas pattern IV was only obtained from poultry. A 95.3% of clones were found in both, humans and poultry. According to these

  15. Drug Resistance Mechanism of Pseudomonas Aeruginosa to Quinolones Antibacterial%铜绿假单胞菌对喹诺酮类抗菌药物的耐药机制

    Institute of Scientific and Technical Information of China (English)

    刘文广

    2012-01-01

    Pseudomonas aeruginosa is an important opportunistic pathogen in nosocomial infection, the resistance of which to quinolones is becoming more and more serious. The main mechanisms of pseudomonas aeruginosa to quinolone resistance are: change of antibacterial drag target site structure to avoid the effect of antibacterial drags; efflux pump system makinge the drag excreted out of bacteria. There are many problems to be further explored for the mechanisms of Pseudomonas aeruginosa resistance to quinolones. Here is to make a review on the research progress.%铜绿假单胞菌是一种重要的医院内感染条件致病菌,对喹诺酮类药物耐药日趋严重.目前发现铜绿假单胞菌对喹诺酮类药物耐药的主要机制为:改变抗菌药物作用的靶位点结构,从而逃避抗菌药物的作用;主动泵出系统使药物排出细菌体外.有关铜绿假单胞菌对喹诺酮类药物的耐药机制,仍存在许多问题有待进一步探索.现就铜绿假单胞菌对喹诺酮类药物的耐药机制研究进展进行综述.

  16. The first report of the qnrB19, qnrS1 and aac(6´-Ib-cr genes in urinary isolates of ciprofloxacin-resistant Escherichia coli in Brazil

    Directory of Open Access Journals (Sweden)

    Magna Cristina Paiva

    2012-08-01

    Full Text Available In this study, we investigated the presence of plasmid-mediated quinolone resistance (PMQR genes among 101 ciprofloxacin-resistant urinary Escherichia coli isolates and searched for mutations in the quinolone-resistance-determining regions (QRDRs of the DNA gyrase and topoisomerase IV genes in PMQR-carrying isolates. Eight isolates harboured the qnr and aac(6'-Ib-cr genes (3 qnrS1, 1 qnrB19 and 4 aac(6'-Ib-cr. A mutational analysis of the QRDRs in qnr and aac(6'-Ib-cr-positive isolates revealed mutations in gyrA, parC and parE that might be associated with high levels of resistance to quinolones. No mutation was detected in gyrB. Rare gyrA, parC and parE mutations were detected outside of the QRDRs. This is the first report of qnrB19, qnrS1 and aac(6'-Ib-cr -carrying E. coli isolates in Brazil.

  17. Quinolone-containing therapies in the eradication of Helicobacter pylori.

    Science.gov (United States)

    Chuah, Seng-Kee; Tai, Wei-Chen; Lee, Chen-Hsiang; Liang, Chih-Ming; Hu, Tsung-Hui

    2014-01-01

    Fluoroquinolones, especially levofloxacin, are used in the eradication of Helicobacter pylori worldwide. Many consensus guidelines recommend that the second-line rescue therapy for H. pylori eradication consists of a proton pump inhibitor, a quinolone, and amoxicillin as an option. Unfortunately, quinolone is well associated with a risk of developing bacterial resistance. In this paper, we review quinolone-containing H. pylori eradication regimens and the challenges that influence the efficacy of eradication. It is generally suggested that the use of levofloxacin should be confined to "rescue" therapy only, in order to avoid a further rapid increase in the resistance of H. pylori to quinolone. The impact of quinolone-containing H. pylori eradication regimens on public health issues such as tuberculosis treatment must always be taken into account. Exposure to quinolone is relevant to delays in diagnosing tuberculosis and the development of drug resistance. Extending the duration of treatment to 14 days improves eradication rates by >90%. Tailored therapy to detect fluoroquinolone-resistant strains can be done by culture-based and molecular methods to provide better eradication rates. Molecular methods are achieved by using a real-time polymerase chain reaction to detect the presence of a gyrA mutation, which is predictive of treatment failure with quinolones-containing triple therapy.

  18. Research on the new resistance mechanism of quinolones mediated by aac(6')-Ib-cr%aac(6')-Ib-cr介导的喹喏酮类新耐药机制研究进展

    Institute of Scientific and Technical Information of China (English)

    孙攀; 殷瑜; 陈代杰

    2009-01-01

    AAC(6')- Ib are important aminoglycoside acetyltransferases.The variable gene aac(6')-Ib-cr acts on both quinolones and aminoglycosides, which belong to different classes of antibiotics based on their chemical structures, leading to the bacteria resistance. This paper briefly reviews the new resisitant mechanism of quinolones mediated by aac(6')-Ib-cr.%AAC(6')-Ib是重要的氨基糖苷乙酰基团转移酶,其变异基因aac(6')-Ib-cr可同时作用于氨基糖苷类和氟喹诺酮类两类结构不同的抗生素,是引起细菌耐药性的一种重要作用机制.该文主要对aac(6')-Ib-cr介导的喹诺酮类新耐药机制相关研究进行综述.

  19. Prevalence of plasmid-mediated AmpC β-lactamase-producing Escherichia coli and spread of the ST131 clone among extended-spectrum β-lactamase-producing E. coli in Japan.

    OpenAIRE

    2012-01-01

    In 2010, a total of 1327 clinical Escherichia coli isolates from five hospitals in the Kyoto and Shiga regions of Japan were analysed by PCR. The prevalences of plasmid-mediated AmpC β-lactamase (pAmpC)-producers, extended-spectrum β-lactamase (ESBL)-producers and co-producers of pAmpC and ESBL were 1.7%, 9.7% and 0.3%, respectively. Less than one-half of the pAmpC-producers were reported to be resistant to third-generation cephalosporins, cephamycins and β-lactam/β-lactam inhibitors using th...

  20. First survey on antibiotic resistance markers in Enterobacteriaceae in Cochabamba, Bolivia.

    Science.gov (United States)

    Saba Villarroel, Paola M; Gutkind, Gabriel O; Di Conza, José A; Radice, Marcela A

    A molecular survey was conducted in Cochabamba, Bolivia, to characterize the mechanism involved in the resistance to clinically relevant antibiotics. Extended Spectrum β-lactamase encoding genes and plasmid-mediated quinolone resistance (PMQR) markers were investigated in a total of 101 oxyimino-cephalosporin-resistant enterobacteria recovered from different health centers during four months (2012-2013). CTX-M enzymes were detected in all isolates, being the CTX-M-1 group the most prevalent (88.1%). The presence of blaOXA-1 was detected in 76.4% of these isolates. A high quinolone resistance rate was observed among the included isolates. The aac(6')-Ib-cr gene was the most frequent PMQR identified (83.0%). Furthermore, 6 isolates harbored the qnrB gene. Interestingly, qepA1 (6) and oqxAB (1), were detected in 7 Escherichia coli, being the latter the first to be reported in Bolivia. This study constitutes the first molecular survey on resistance markers in clinical enterobacterial isolates in Cochabamba, Bolivia, contributing to the regional knowledge of the epidemiological situation. The molecular epidemiology observed herein resembles the scene reported in South America. Copyright © 2016 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

  1. 喹诺酮类药物的耐药、联合用药及不良反应分析%Analysis of drug resistance,drug combination and adverse reactions of quinolones

    Institute of Scientific and Technical Information of China (English)

    孙志勇

    2013-01-01

    目的研究喹诺酮类药物的耐药、联合用药和不良反应。方法对本院应用喹诺酮类药物治疗后出现不良反应的60例患者的临床资料进行回顾性分析。结果常见的不良反应主要为全身性损伤(14例,23.4%)、皮肤方面的损伤(12例,20.0%)和神经系统损伤(18例,30.0%)。喹诺酮类药物目前的耐药情况比较严重。结论喹诺酮类药物应合理使用,并掌握其临床适应证以及剂量,尽可能避免联合用药的不合理性和不良反应的发生。%Objective To investigate the resistance,drug combination and adverse reactions of quinolones. Methods Clinical data of 60 patients who had adverse reactions after using quinolones in our hospital were collected and analyzed retrospectively. Results The main common adverse reactions were systemic injury(14 patients,23.4%),skin injury (12 patients,20.0%) and nervous system injury(18 patients,30.0%). The current drug resistance situation of quinolones was severe. Conclusion Quinolones should be used rationally and their clinical indications and doses should be mastered in order to avoid the irrationality of drug combination and the occurrence of adverse reactions.

  2. Antibiotic susceptibility pattern of Salmonella enterica serovar typhi and Salmonella enterica serovar paratyphi A with special reference to quinolone resistance

    Directory of Open Access Journals (Sweden)

    Shoorashetty Manohar Rudresh

    2015-01-01

    Full Text Available Background and Objectives: Typhoid fever is endemic in India. Extensive use of first-line antibiotics has led to the emergence of multi-drug resistant (MDR Salmonella typhi. Ciprofloxacin has become empirical therapy of choice against MDR salmonellae. Recent year′s emergence of low-level ciprofloxacin resistance in salmonellae resulted in delayed response and serious complications. Nalidixic acid (NA screen test is used as surrogate marker for detection low-level ciprofloxacin resistance. In this study, we evaluated prevalence of MDR and low-level ciprofloxacin resistant S. typhi and Salmonella paratyphi A. Materials and Methods: A total of 50 blood culture isolates of S. typhi and S. paratyphi A were tested for antibiotic susceptibility according to Clinical Laboratory Standards Institute (CLSI method. Minimal inhibitory concentration (MIC to ciprofloxacin was carried out by E-test and agar dilution method. Results: Among the 50 salmonella isolates, 80% were S. typhi and 20% were S. paratyphi A. MDR was found in 2% S. typhi. NA resistant salmonellae showed ciprofloxacin MIC ranging from 0.25 to 0.75 μg/ml. One isolate of S. typhi showed ciprofloxacin MIC of 32 μg/ml and was also resistant to ceftriaxone. NA screen test for low-level ciprofloxacin resistance was 100% sensitive and 97.9% specific. Interpretation and Conclusion: NA resistant isolates should be tested for ciprofloxacin MIC to decide therapeutic options. The current CLSI breakpoints may have to be re-evaluated for salmonellae.

  3. New Role of Quinolones in Respiratory Tract Infections

    Directory of Open Access Journals (Sweden)

    Ronald F Grossman

    1998-01-01

    Full Text Available Because of limited activity of the standard quinolones such as ciprofloxacin and ofloxacin against some clinically important organisms including Streptococcus pneumoniae and methicillin-resistant Staphylococcus aureus, new quinolones have been developed. In addition to their improved activity against S pneumoniae, some also demonstrate excellent anaerobic activity. None of the quinolones have a role to play in the treatment of paediatric infections. Quinolones (both older and newer agents have demonstrated equivalent efficacy to standard antimicrobials in the treatment of acute sinusitis. Several groups have suggested that quinolones are excellent agents in the treatment of high risk patients with acute exacerbations of chronic bronchitis. These patients include the elderly, and those with frequent exacerbations, significant comorbid conditions. long duration of chronic bronchitis and major impairment of lung function. There is no evidence to suggest that the newer quinolones will differ from the currently available agents for th is disease. The major advantage of the newer quinolones appears to be in the treatment of patients with community-acquired pneumonia where pneumococcal infection is a real concern. A new parenteral quinolone with pneumococcal activity may replace the standard macrolide/cephalosporin combination that is commonly prescribed. For patients with nosocomial pneumonia, the newer agents are alternative choices, especially among patients with early onset pneumonia (less than five days of hospitalization, but are unlikely to replace ciprofloxacin in the intensive care unit setting because of poor Pseudomonas aeruginosa coverage.

  4. Occurrence of quinolone- and beta-lactam-resistant Escherichia coli in danish broiler flocks

    DEFF Research Database (Denmark)

    Bortolaia, Valeria; Guardabassi, Luca; Bisgaard, Magne

    An increased concern for the possible transfer of resistant bacteria or mobile resistance elements from food animals to humans has resulted in rigorous legislation preventing i.e. practical use of fluoroquinolones in the Danish broiler industry (Olesen et al., 2004; Petersen et al., 2006). In Den......An increased concern for the possible transfer of resistant bacteria or mobile resistance elements from food animals to humans has resulted in rigorous legislation preventing i.e. practical use of fluoroquinolones in the Danish broiler industry (Olesen et al., 2004; Petersen et al., 2006......, and F. M. Aarestrup. 2004. Prevalence of ß-lactamases among ampicillin-resistant Escherichia coli and Salmonella isolated from food animals in Denmark. Micr. Drug Res. 10:334-340. Petersen, A., J. P. Christensen, P. Kuhnert, M. Bisgaard, J. E. Olsen. 2006. Vertical transmission of a fluoroquinolone...

  5. Shigellosis in Bay of Bengal Islands, India: clinical and seasonal patterns, surveillance of antibiotic susceptibility patterns, and molecular characterization of multidrug-resistant Shigella strains isolated during a 6-year period from 2006 to 2011.

    Science.gov (United States)

    Bhattacharya, D; Bhattacharya, H; Thamizhmani, R; Sayi, D S; Reesu, R; Anwesh, M; Kartick, C; Bharadwaj, A P; Singhania, M; Sugunan, A P; Roy, S

    2014-02-01

    This study aims to determine the clinical features and seasonal patterns associated with shigellosis, the antimicrobial resistance frequencies of the isolates obtained during the period 2006-2012 for 22 antibiotics, and the molecular characterization of multidrug-resistant strains isolated from endemic cases of shigellosis in the remote islands of India, with special reference to fluoroquinolone and third-generation cephalosporins resistance. During the period from January 2006 to December 2011, stool samples were obtained and processed to isolate Shigella spp. The isolates were evaluated with respect to their antibiotic resistance pattern and various multidrug resistance determinants, including resistance genes, quinolone resistance determinants, and extended-spectrum β-lactamase (ESBL) production. Morbidity for shigellosis was found to be 9.3 % among children in these islands. Cases of shigellosis occurred mainly during the rainy seasons and were found to be higher in the age group 2-5 years. A wide spectrum of resistance was observed among the Shigella strains, and more than 50 % of the isolates were multidrug-resistant. The development of multidrug-resistant strains was found to be associated with various drug-resistant genes, multiple mutations in the quinolone resistance-determining region (QRDR), and the presence of plasmid-mediated quinolone-resistant determinants and efflux pump mediators. This report represents the first presentation of the results of long-term surveillance and molecular characterization concerning antimicrobial resistances in clinical Shigella strains in these islands. Information gathered as part of the investigations will be instrumental in identifying emerging antimicrobial resistance, for developing treatment guidelines appropriate for that community, and to provide baseline data with which to compare outbreak strains in the future.

  6. Whole-genome sequencing identifies emergence of a quinolone resistance mutation in a case of Stenotrophomonas maltophilia bacteremia.

    Science.gov (United States)

    Pak, Theodore R; Altman, Deena R; Attie, Oliver; Sebra, Robert; Hamula, Camille L; Lewis, Martha; Deikus, Gintaras; Newman, Leah C; Fang, Gang; Hand, Jonathan; Patel, Gopi; Wallach, Fran; Schadt, Eric E; Huprikar, Shirish; van Bakel, Harm; Kasarskis, Andrew; Bashir, Ali

    2015-11-01

    Whole-genome sequences for Stenotrophomonas maltophilia serial isolates from a bacteremic patient before and after development of levofloxacin resistance were assembled de novo and differed by one single-nucleotide variant in smeT, a repressor for multidrug efflux operon smeDEF. Along with sequenced isolates from five contemporaneous cases, they displayed considerable diversity compared against all published complete genomes. Whole-genome sequencing and complete assembly can conclusively identify resistance mechanisms emerging in S. maltophilia strains during clinical therapy.

  7. The culturable soil antibiotic resistome: a community of multi-drug resistant bacteria.

    Directory of Open Access Journals (Sweden)

    Fiona Walsh

    Full Text Available Understanding the soil bacterial resistome is essential to understanding the evolution and development of antibiotic resistance, and its spread between species and biomes. We have identified and characterized multi-drug resistance (MDR mechanisms in the culturable soil antibiotic resistome and linked the resistance profiles to bacterial species. We isolated 412 antibiotic resistant bacteria from agricultural, urban and pristine soils. All isolates were multi-drug resistant, of which greater than 80% were resistant to 16-23 antibiotics, comprising almost all classes of antibiotic. The mobile resistance genes investigated, (ESBL, bla NDM-1, and plasmid mediated quinolone resistance (PMQR resistance genes were not responsible for the respective resistance phenotypes nor were they present in the extracted soil DNA. Efflux was demonstrated to play an important role in MDR and many resistance phenotypes. Clinically relevant Burkholderia species are intrinsically resistant to ciprofloxacin but the soil Burkholderia species were not intrinsically resistant to ciprofloxacin. Using a phenotypic enzyme assay we identified the antibiotic specific inactivation of trimethoprim in 21 bacteria from different soils. The results of this study identified the importance of the efflux mechanism in the soil resistome and variations between the intrinsic resistance profiles of clinical and soil bacteria of the same family.

  8. Low rates of antimicrobial-resistant Enterobacteriaceae in wildlife in Tai National Park, Cote d'Ivoire, surrounded by villages with high prevalence of multiresistant ESBL-producing Escherichia coli in people and domestic animals.

    Directory of Open Access Journals (Sweden)

    Katerina Albrechtova

    Full Text Available Antimicrobial resistance genes can be found in all ecosystems, including those where antibiotic selective pressure has never been exerted. We investigated resistance genes in a collection of faecal samples of wildlife (non-human primates, mice, people and domestic animals (dogs, cats in Côte d'Ivoire; in the chimpanzee research area of Taï National Park (TNP and adjacent villages. Single bacteria isolates were collected from antibiotic-containing agar plates and subjected to molecular analysis to detect Enterobacteriaceae isolates with plasmid-mediated genes of extended-spectrum beta-lactamases (ESBLs and plasmid-mediated quinolone resistance (PMQR. While the prevalence of ESBL-producing E. coli in the villages was 27% in people (n = 77 and 32% in dogs (n = 38, no ESBL-producer was found in wildlife of TNP (n = 75. PMQR genes, mainly represented by qnrS1, were also present in human- and dog-originating isolates from the villages (36% and 42% in people and dogs, respectively, but no qnrS has been found in the park. In TNP, different variants of qnrB were detected in Citrobacter freundii isolates originating non-human primates and mice. In conclusion, ESBL and PMQR genes frequently found in humans and domestic animals in the villages were rather exceptional in wildlife living in the protected area. Although people enter the park, the strict biosecurity levels they are obliged to follow probably impede transmission of bacteria between them and wildlife.

  9. Evaluation of quinolone antibacterial consumption

    Directory of Open Access Journals (Sweden)

    E. P. Bernaz

    2016-08-01

    Full Text Available Quinolones are broad-spectrum antibiotics that play an important role in the treatment of serious bacterial infections, especially hospital-acquired infections and others in which resistance to older antibacterial classes is suspected and as first-line therapy is recommended. To determine the place, compare and analyze the use of quinolone antibacterial in the most important departments of EMI during 2009 to 2014 and to assess their results for improvement of patients treatment quality was designed this study. In the evaluated period consumption of quinolone antibacterial in EMI recorded a decline from 91 to 46 DDD/1000 or by 49.45%, in IC departaments from 338.6 to 132.07 or by 61%, and vice versa in SSOT departments an increase from 41.28 to 57.59 DDD/1000 or by 31.51%. Medium annual consumption in all institution recorded 63.03 DDD/1000, respectvely 174.90 in IC and 45.10 in SSOT departments. In 2014 IC departments recorded 2439.8 lei per DDD/1000, that was 8.72 times more than cost of 279.9 lei in SSOT departments and 7.51 times than 324.96 lei per DDD/1000 in all EMI. The yearly medium in EMI is around the same with all other international hospitals of 66.13 DDD/1000 and by 27.23% higher than 49.54 DDD/1000 recorded in large acute Australian public hospitals. The obtained results will be an important data for optimization in planning annual hospital necessities and rational antimicrobial prescribing as well as suggest the idea for expansion development and support antimicrobial stewardship initiatives.

  10. Use of antibiotics and about quinolones in veterinary therapy (ro

    Directory of Open Access Journals (Sweden)

    Crina L. Mosneang

    2012-12-01

    Full Text Available In Romania are being done extensively efforts in the veterinarians education to emphasize the importance and the European regulations familiar behavior, relating to veterinary drugs prescribing, the issues of residues, of antibacterial resistance and of judicious use of the veterinary conditionigs. In this respect, the present synthesis presents an overview, a useful and necessary bibliographical remembrance to veterinary practitioner about antibiotics and quinolones in particular. Are summarized: bacterial antagonism, methods for studying the effectiveness of antibiotics, the mode of action of antibiotics, the phenomenon of resistance to antibiotics and toxic secondary phenomena caused by antibiotics, continued by information about quinolone-carbonic acid derivatives (quinolones them action mechanism, classification and presentation of the main representatives, indications and contraindications, etc. Referate is conceived in two parts about antibiotics and about quinolones.

  11. 耐碳青霉烯类与喹诺酮类肺炎克雷伯菌的耐药机制研究%Investigation of resistant mechanism of carbapenem and quinolone-resistant Klebsiella pneumoniae

    Institute of Scientific and Technical Information of China (English)

    郑红波; 黄东标; 王祥德

    2014-01-01

    OBJECTIVE To investigate the resistant mechanism of 20 strains of carbapenem-and quinolone-resistant K lebsiella pneumoniae .METHODS Totally 20 strains of K . pneumoniae were isolated from sputum specimens from inpatients in a third-grade hospital from Jan .to Jun .2012 .The modified Hodge test was performed to detect activities of carbapenemase ,then 40 kinds of class A-D beta-lactamase genes and quinolone-resistant genes were analyzed by PCR .RESULTS The modified Hodge test showed all 20 strains had carbapenemase activities ,TEM-1 and K PC-2 were all positive ,and TCC→ATC mutation emerged in 83rd codon of gyrA (amino acid sequence S→I) ,and GAC → GGC mutation emerged in 87th codon of gyrA (amino acid sequence D → G) .CONCLUSION Carrying K PC-2 and mutations of QRDR in gyrA was the resistant mechanism of carbapenem- and quinolone-resistant K . pneumoniae ,and the coincidence of phenotypes and genotypes suggested that hospital infection existed .%目的:研究20株耐碳青霉烯类与喹诺酮类肺炎克雷伯菌的耐药机制。方法20株肺炎克雷伯菌分离自2012年1-6月医院住院患者的痰液样本,采用改良的 Hodge试验检测碳青霉烯酶活性,再用PCR法检测A~D类40种β-内酰胺酶基因和喹诺酮类耐药基因。结果20株肺炎克雷伯菌经改良的Hodge试验检测均有碳青霉烯酶活性,均检出 TEM-1和 K PC-2型β-内酰胺酶基因,出现 gyrA基因第83位密码子 TCC→ATC突变(氨基酸序列S→I),第87位密码子GAC→GGC突变(氨基酸序列D→G )。结论肺炎克雷伯菌携带 K PC-2型β-内酰胺酶基因和存在 gyrA基因QRDR区突变,其是碳青霉烯类与喹诺酮类药物的耐药机制,肺炎克雷伯菌药敏表型与耐药基因型相同疑似医院感染。

  12. Prevalence and characterization of cefotaxime and ciprofloxacin co-resistant Escherichia coli isolates in retail chicken carcasses and Ground Pork, China.

    Science.gov (United States)

    Xu, Xiao; Cui, Shenghui; Zhang, Fenglan; Luo, Yanping; Gu, Yihai; Yang, Baowei; Li, Fengqin; Chen, Qian; Zhou, Gang; Wang, Yeru; Pang, Lu; Lin, Lan

    2014-02-01

    Retail meat products could serve as an important medium for the transfer of multidrug resistant isolates from food-producing animals to the community. In this study, the prevalence and characteristics of cefotaxime and ciprofloxacin co-resistant Escherichia coli isolates were investigated in retail chicken and ground pork samples from four provinces of China. The isolates were subjected to phylogenetic group typing and antimicrobial susceptibility testing. All isolates were further characterized by pulsed-field gel electrophoresis to determine the genetic relatedness. These isolates were also screened for beta-lactamase genes, quinolone resistance determinants by PCR, and followed by DNA sequence analysis. Cefotaxime and ciprofloxacin co-resistant E. coli isolates with diverse genetic origins were recovered in 31.9% (106/332) of retail meat samples. E. coli isolates of phylogenetic group A were dominant (59.4%, 63/106), and all isolates showed multidrug resistant profiles. The dominant resistant profiles were AMP-CAZ-CTX-CIP-CHL-GEN-SXT-TET (n=43) and AMP-CAZ-CTX-CIP-CHL-SXT-TET (n=43). Point mutations in quinolone resistance determination regions of topoisomerases were identified in all the isolates, and most of the isolates accumulated three (n=78) or four (n=21) point mutations. Plasmid-mediated quinolone-resistant determinants were identified in 68 isolates, including oqxAB (n=66), qnrS1 (n=7), qnrS2 (n=4), and aac(6')-Ib-cr (n=9). Eight subtypes of bla(CTX-M) were identified in 103 E. coli isolates, and blaCTX-M-55 (n=90) was dominant. This study highlights that retail meat could serve as an important reservoir of cefotaxime and ciprofloxacin co-resistant E. coli isolates. It is necessary to evaluate their contribution in the community and hospital infections.

  13. Characterization of fluoroquinolone resistance and qnr diversity in Enterobacteriaceae from municipal biosolids.

    Directory of Open Access Journals (Sweden)

    Ella eKaplan

    2013-06-01

    Full Text Available Municipal biosolids produced during activated sludge treatment applied in waste water treatment plants, are significant reservoirs of antibiotic resistance, since they assemble both natural and fecal microbiota, as well as residual concentrations of antibiotic compounds. This raises major concerns regarding the environmental and epidemiological consequences of using them as fertilizers for crops. The second generation fluoroquinolone ciprofloxacin is probably the most abundant antibiotic compound detected in municipal biosolids due to its widespread use and sorption properties. Although fluoroquinolone resistance was originally thought to result from mutations in bacterial gyrase and topoisomerase IV genes, it is becoming apparent that it is also attributed to plasmid-associated resistance factors, which may propagate environmental antibiotic resistance. The objective of this study was to assess the impact of the activated sludge process on fluoroquinolone resistance. The scope of resistances and mobile genetic mechanisms associated with fluoroquinolone resistance were evaluated by screening large collections of ciprofloxacin-resistant Enterobacteriaceae strains from sludge (n=112 and from raw sewage (n=89. Plasmid-mediated quinolone resistance determinants (qnrA, B and S were readily detected in isolates from both environments, the most dominant being qnrS. Interestingly, all qnr variants were significantly more abundant in sludge isolates than in the isolates from raw sewage. Almost all of ciprofloxacin-resistant isolates were resistant to multiple antibiotic compounds. The sludge isolates were on the whole resistant to a broader range of antibiotic compounds than the raw sewage isolates; however this difference was not statistically significant. Collectively, this study indicates that the activated sludge selects for multiresistant bacterial strains, and that mobile quinolone-resistance elements may have a selective advantage in the activated

  14. Analysis of the Fluoroquinolone Antibiotic Resistance Mechanism of Salmonella enterica Isolates.

    Science.gov (United States)

    Kim, Soo-Young; Lee, Si-Kyung; Park, Myeong-Soo; Na, Hun-Taek

    2016-09-28

    Quinolone-resistant Salmonella strains were isolated from patient samples, and several quinolone-sensitive strains were used to analyze mutations in the quinolone resistance-determining region (QRDR) of gyrA, gyrB, parC, and parE and to screen for plasmid-mediated quinolone resistance. Among the 21 strains that showed resistance to nalidixic acid and ciprofloxacin (MIC 0.125-2.0 μg/ml), 17 strains had a mutation in QRDR codon 87 of gyrA, and 3 strains had a single mutation (Ser83 → Phe). Another cause of resistance, efflux pump regulation, was studied by examining the expression of acrB, ramA, marA, and soxS. Five strains, including Sal-KH1 and Sal-KH2, showed no increase in relative expression in an analysis using the qRT-PCR method (p < 0.05). In order to determine the genes involved in the resistance, the Sal-9 isolate that showed decreased susceptibility and did not contain a mutation in the gyrA QRDR was used to make the STM (MIC 8 μg/ml) and STH (MIC 16 μg/ml) ciprofloxacin-resistant mutants. The gyrA QRDR Asp87 → Gly mutation was identified in both the STM and STH mutants by mutation analysis. qRT-PCR analysis of the efflux transporter acrB of the AcrAB-TolC efflux system showed increased expression levels in both the STM (1.79-fold) and STH (2.0-fold) mutants. In addition, the expression of the transcriptional regulator marA was increased in both the STM (6.35-fold) and STH (21.73-fold) mutants. Moreover, the expression of soxS was increased in the STM (3.41-fold) and STH (10.05-fold) mutants (p < 0.05). Therefore, these results indicate that AcrAB-TolC efflux pump activity and the target site mutation in gyrA are involved in quinolone resistance.

  15. Ciprofloxacin-resistant Escherichia coli in Central Greece: mechanisms of resistance and molecular identification

    Directory of Open Access Journals (Sweden)

    Mavroidi Angeliki

    2012-12-01

    Full Text Available Abstract Background Fluoroquinolone resistant E. coli isolates, that are also resistant to other classes of antibiotics, is a significant challenge to antibiotic treatment and infection control policies. In Central Greece a significant increase of ciprofloxacin-resistant Escherichia coli has occurred during 2011, indicating the need for further analysis. Methods A total of 106 ciprofloxacin-resistant out of 505 E. coli isolates consecutively collected during an eight months period in a tertiary Greek hospital of Central Greece were studied. Antimicrobial susceptibility patterns and mechanisms of resistance to quinolones were assessed, whereas selected isolates were further characterized by multilocus sequence typing and β-lactamase content. Results Sequence analysis of the quinolone-resistance determining region of the gyrA and parC genes has revealed that 63% of the ciprofloxacin-resistant E. coli harbored a distinct amino acid substitution pattern (GyrA:S83L + D87N; ParC:S80I + E84V, while 34% and 3% carried the patterns GyrA:S83L + D87N; ParC:S80I and GyrA:S83L + D87N; ParC:S80I + E84G respectively. The aac (6’-1b-cr plasmid-mediated quinolone resistance determinant was also detected; none of the isolates was found to carry the qnrA, qnrB and qnrS. Genotyping of a subset of 35 selected ciprofloxacin-resistant E. coli by multilocus sequence typing has revealed the presence of nine sequence types; ST131 and ST410 were the most prevalent and were exclusively correlated with hospital and health care associated infections, while strains belonging to STs 393, 361 and 162 were associated with community acquired infections. The GyrA:S83L + D87N; ParC:S80I + E84V substitution pattern was found exclusively among ST131 ciprofloxacin-resistant E. coli. Extended-spectrum β-lactamase-positive ST131 ciprofloxacin-resistant isolates produced CTX-M-type enzymes; eight the CTX-M-15 and one the CTX-M-3 variant. CTX-M-1 like and KPC-2 enzymes were detected

  16. Analysis of antimicrobial resistance of Acinetobacter baumannii to quinolones%鲍氏不动杆菌对喹诺酮类抗菌药物的耐药性分析

    Institute of Scientific and Technical Information of China (English)

    王宝英; 张凤民; 王洪; 孟凡飞; 徐晖; 付英梅; 王金冬; 方文娟; 尤玉红; 钟秀丽

    2012-01-01

    目的 分析临床分离的鲍氏不动杆菌对喹诺酮类抗菌药物的耐药特点及耐药机制.方法 采用K-B纸片法测定33株鲍氏不动杆菌对喹诺酮类等21种抗菌药物的耐药性;用PCR技术扩增33株鲍氏不动杆菌的gyrA基因的耐药决定区,PCR产物经纯化后测序与GenBank中的标准序列比较,分析其突变情况.结果 33株鲍氏不动杆菌中,8株对环丙沙星耐药,占24.2%,4株对左氧氟沙星耐药占12.1%;对环丙沙星耐药的8个菌株均有gyrA基因突变,导致氨基酸变异为Ser-83→Leu,其中包括对左氧氟沙星耐药的4个菌株;所有对环丙沙星敏感的菌株未出现gyrA基因突变.结论 gyrA基因突变决定鲍氏不动杆菌对喹诺酮类抗菌药物的耐药.%OBJECTIVE To analyze the drug resistance characteristics and mechanisms to quinolones in 33 clinical isolates of Acinetobacter baumannii in Harbin. METHODS A total of 33 strains of A. Baumannii were collected and their susceptibility to 21 antimicrobial agents was determined by K-B disk diffusion method. Quinolone resistance determining regions in gyrA gene were amplified by PCR and the PCR products were purified and sequenced, which were then compared with the standard sequences in the GenBank to analyze mutations. RESULTS The resistance rates of A. Baumannii to ciprofloxacin and levofloxacin were 24. 2% (8/33) and 12. 1% (4/33) , respectively. DNA sequencing showed that all the ciprofloxacin-resistant isolates had gyrA mutation (Ser-83→Leu in 8 strains), which included the four isolates resistant to levofloxacin. No gyrA gene mutation was found in ciprofloxacin-susceptible strains. CONCLUSION Drug resistance of clinical isolates of A. Baumannii to quinolones is determined by the mutation in gyrA.

  17. Antibiotic resistance in Escherichia coli in husbandry animals: the African perspective.

    Science.gov (United States)

    Alonso, C A; Zarazaga, M; Ben Sallem, R; Jouini, A; Ben Slama, K; Torres, C

    2017-05-01

    In the last few years, different surveillances have been published in Africa, especially in northern countries, regarding antimicrobial resistance among husbandry animals. Information is still scarce, but the available data show a worrying picture. Although the highest resistance rates have been described against tetracycline, penicillins and sulphonamides, prevalence of plasmid-mediated quinolone resistance genes and extended spectrum β-lactamase (ESBL) are being increasingly reported. Among ESBLs, the CTX-M-1 group was dominant in most African surveys. Within this group, CTX-M-15 was the main variant both in animals and humans, except in Tunisia where CTX-M-1 was more frequently detected among Escherichia coli from poultry. Certain blaCTX-M-15 -harbouring clones (ST131/B2 or ST405/D) are mainly identified in humans, but they have also been reported in livestock species from Tanzania, Nigeria or Tunisia. Moreover, several reports suggest an inter-host circulation of specific plasmids (e.g. blaCTX-M-1 -carrying IncI1/ST3 in Tunisia, IncY- and Inc-untypeable replicons co-harbouring qnrS1 and blaCTX-M-15 in Tanzania and the worldwide distributed blaCTX-M-15 -carrying IncF-type plasmids). International trade of poultry meat seems to have contributed to the spread of other ESBL variants, such as CTX-M-14, and clones. Furthermore, first descriptions of OXA-48- and OXA-181-producing E. coli have been recently documented in cattle from Egypt, and the emergent plasmid-mediated colistin resistance mcr-1 gene has been also identified in chickens from Algeria, Tunisia and South Africa. These data reflect the urgent need of a larger regulation in the use of veterinary drugs and the implementation of surveillance programmes in order to decelerate the advance of antimicrobial resistance in this continent. © 2017 The Society for Applied Microbiology.

  18. Characterization of carbapenemases, extended spectrum β-lactamases, quinolone resistance and aminoglycoside resistance determinants in carbapenem-non-susceptible Escherichia coli from a teaching hospital in Chongqing, Southwest China.

    Science.gov (United States)

    Zhang, Chuanming; Xu, Xiuyu; Pu, Shuli; Huang, Shifeng; Sun, Jide; Yang, Shuangshuang; Zhang, Liping

    2014-10-01

    Carbapenem-resistant Escherichiacoli isolates harboring carbapenemases or combining an extended-spectrum β-lactamase (ESBL) enzyme with loss of porins present an increasingly urgent clinical danger. Combined resistance to aminoglycosides and fluoroquinolones in carbapeneme non-susceptible (CNS) isolates will inevitably create problems. In the current study, we characterized the carbapenemases and ESBLs, and the prevalence of quinolone resistance determinants and aminoglycoside resistance determinants in carbapenem-non-susceptible (CNS) E.coli isolates from a teaching hospital in Chongqing, Southwest China in 2012. Thirty non-duplicated CNS E.coli isolates were screened via antimicrobial susceptibility testing, and the drug resistance profiles of the 30 strains were analyzed. Carbapenemase genes blaKPC-2, ESBL genes including blaCTX-M-3, blaCTX-M-14, blaCTX-M-55 and blaTEM, ARD genes including aac(6')-Ib, armA and rmtB, and QRD genes including qnrA, qnrB, qnrC, qnrD, qnrS and aac(6')-Ib-cr were identified and clonal relatedness was investigated by pulsed-field gel electrophoresis. Of the 30 isolates, 2 (6.7%) harbored carbapenemase gene blaKPC-2; 29 (96.7%) carried ESBLs; 20 (66.7%) were QRD positive; and 11 (36.7%) were ARD positive. Between the two blaKPC-2 positive strains, one contained ESBL, QRD and ARD genes, while the other expressed ESBL genes but was negative for both QRD and ARD genes. Of the 29 ESBLs positive isolates, 2 (6.9%) were carbapenemase positive, 19 (65.5%) were QRD positive, and 11 (37.9%) were ARD positive. PFGE revealed genetic diversity among the 30 isolates, indicating that the high prevalence of CNS E. coli isolates was not caused by clonal dissemination. Production of ESBLs was associated with the carbapenem resistance and QRD genes were highly prevalent among the CNS E. coli isolates. Multiple resistant genes were co-expressed in the same isolates. This is the first report of a multidrug resistant carbapenem-non-susceptible E.coli co

  19. Quinolone resistance and gyr gene mutations in multi-drug resistant of Mycobacterium tuberculosis%耐多药结核分枝杆菌对喹诺酮类药物的耐药性与gyr基因突变的初步研究

    Institute of Scientific and Technical Information of China (English)

    赵丽丽; 夏强; 赵秀芹; 刘志广; 万康林

    2011-01-01

    目的 分析耐多药结核分枝杆菌(Multiple drug-resistant tuberculosis,MDR-TB)临床分离株的gyr基因突变特点,探讨MDR-TB对喹诺酮类药物耐药产生与gyr基因突变的关系.方法 采用比例法对耐多药结核临床分离菌株进行氧氟沙星的药物敏感性检测,应用DNA直接测序法检测MDR-TB的gyr基因突变情况.结果 125株MDR-TB临床分离株中,50株对喹诺酮类耐药,耐药率为40%.50株耐药菌株中,40株gyr基因发生突变:其中39株gyrA基因突变,突变率为78%,突变位点包括90,91和94位氨基酸;5株gyrB基因突变,其中4株合并gyrA基因突变,gyrB基因突变位点为500,506,534和539位氨基酸.结论 MDR-TB中的喹诺酮类药物耐药态势比较严峻,其对喹诺酮类药物耐药机制主要与gyrA基因突变有关.%In order ot analyze the characteristics of gyr gene mutations in clinical isolates from the patients with multidrug resistant tuberculosis (MDR-TB) and the relation between MDR-TB with quinolone resistance and gyr gene mutations,the susceptibility of the MDR-TB clinical isolates to quinolones was tested by the proportion method.Gyr gene mutations of MDR-TB strains were detected by direct DNA sequencing.The results showed that there were 50 strains with quinolone resistance in 125 MDR-TB clinical isolates.The quinolone resistance rate was 40%.There were 40 with gyr mutations in 50 MDRTB with quinolone resistance.Of 40 quinolone resistant MDR-TB with gyr mutations, 39 mutated at condon 90, 91 and 94 of gyrA gene with a mutation rate of 78%.For 5 gyrB mutatans, 4 were associated with gyrA gene mutations.The mutation sites of gyrB were at condon 500, 506, 534 and 539 of gyrB gene.This study shows that the situation of MDR-TB with quinolone resistance is very serious.The mechanism of quinolone resistance in MDR-TB is mainly in connection with the mutation of gyrA gene.

  20. Detection of extended spectrum beta-lactamases and resistance in members of the Enterobacteriaceae family isolated from healthy sheep and dogs in Umuarama, Paraná, Brazil

    Directory of Open Access Journals (Sweden)

    Patricia Alves de Oliveira

    2016-04-01

    Full Text Available Bacterial resistance is a primary public health concern worldwide. Within this context, pets and breeding animals act as reservoirs for multidrug-resistant bacteria (MR, such as those producing extended spectrum beta-lactamases (ESBL and those presenting plasmid-mediated quinolone resistance (PMQR. The aim of this study was to detect the presence of ESBL and PMQR in members of the Enterobacteriaceae family, isolated from healthy sheep and dogs from non-intense farming rural properties in the Umuarama region of Paraná, Brazil. A total of 81 oral and rectal swabs from dogs and sheep from 11 small rural properties were analyzed. These swabs were inoculated in tubes containing brain heart infusion broth (BHI, and the resulting cultures were inoculated on MacConkey agar (MAC supplemented with 10 ?g/mL cefotaxime for the selection of ESBL producers. The cells were also plated on MAC supplemented with 50 ?g/mL nalidixic acid for selecting quinolone-resistant enterobacteria. The bacterial isolates were subjected to biochemical identification tests, antibiograms, double-disk synergic tests, and polymerase chain reaction analysis for resistance-inducing genes (blaESBL, qnr, and genes encoding efflux pump and acetylases. Four (5.00% bacterial isolates (3 Escherichia coli and 1 Morganella morganii resistant to cephalosporins and/or quinolones were identified; of these, three (75% isolates were from sheep and one (25% from a dog. These findings indicate the presence of MR bacteria in the normal microbiota of the animals studied. Animals colonized with such bacteria can contribute to the dissemination of antimicrobial resistance to other animals, environment, and/or human beings and can harbor endogenous infections in unfavorable conditions, which have poor prognosis due to the limited therapeutic options.

  1. Quinolones in the treatment of Salmonella carriers.

    Science.gov (United States)

    Rodríguez-Noriega, E; Andrade-Villanueva, J; Amaya-Tapia, G

    1989-01-01

    Infections caused by Salmonella typhi are commonly followed by a chronic carrier state despite positive clinical and initial bacteriologic responses. The use of primary antibiotics like chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole has several major drawbacks, including in some instances the failure to prevent the carrier state. The appearance worldwide of strains with multiple resistance to the most commonly used regimens has prompted the search for new forms of therapy. Among the agents studied have been third-generation cephalosporins and quinolones, which are active in vitro against bacterial enteropathogens like S. typhi. Resolution of chronic carriage of S. typhi and other salmonellae is difficult, and regimens commonly fail (including those that combine antibiotic administration with removal of the gallbladder). In addition to being active in vitro against Salmonella species, the newer quinolones adequately penetrate the intestinal lumen, liver, bile, and gallbladder. Initial experience with norfloxacin and ciprofloxacin in oral treatment of the chronic S. typhi carrier state in adults has been promising.

  2. 武汉地区7家医院连续5年喹诺酮类药用药频度与细菌耐药性分析%Analysis of the Use Density and Bacterial Resistance of Quinolones in 5 Consecutive Years in Wuhan

    Institute of Scientific and Technical Information of China (English)

    汪震; 刘东; 沈倩倩; 杜光; 孙自镛

    2012-01-01

    Objective: To investigate the relationship between the use density and bacterial resistance of quinolo-nes. Method: The consumption of quinolones in the past 5 years was investigated and the relationship between their consumption and bacterial resistance was statistically analyzed by linear correlation. Result;The resistance rates of most bacteria monitored exceeded the warning line by 30% . With the change of the use density of quinolones, the resistance rates of Acinetobacter baumannii bacteria changed in the past 5 years. There was a highly correlation between the use density of quinolones and the resistance rates of Acinetobacter baumannii bacteria. Conclusion: The bacterial resistance of quinolones was at a high level. The consumption of quinolones could create their affection on the bacterial resistance in some degree. The application of quinolones should be strictly managed to delay the bacterial resistance.%目的:研究喹诺酮类抗菌药的用量与细菌耐药率之间的关系,促进临床合理用药.方法:回顾性调查武汉地区7家医院2005~2009年喹诺酮类抗菌药的用量,并与监测菌的耐药率做相关分析.结果:大多数监测菌种对喹诺酮类药的耐药率均超过30%;鲍曼不动杆菌对喹诺酮类药的耐药率随喹诺酮类药用量的变化而变化,与喹诺酮类药总用药频度高度相关.结论:喹诺酮类药对多数常见菌种的耐药率较高,其用药频度对细菌耐药性变异也有一定影响.应严格把握喹诺酮类药的临床适应证,加强对喹诺酮类药的管理,以减少或延缓细菌耐药性的发生.

  3. Identification of DHA-23, a Novel Plasmid-mediated and Inducible AmpC beta-Lactamase from Enterobacteriaceae in Northern Taiwan

    Directory of Open Access Journals (Sweden)

    Wen-Shyang eHsieh

    2015-05-01

    Full Text Available Objectives: AmpC β-lactamases are classified as Amber Class C and Bush Group 1. AmpC β-lactamases can hydrolyze broad and extended-spectrum cephalosporins, and are not inhibited by β-lactamase inhibitors such as clavulanic acid. This study was conducted to identify DHA-23, a novel plasmid-mediated and inducible AmpC β-lactamase obtained from Enterobacteriaceae. Methods: A total of 210 carbapenem-resistant Enterobacteriaceae isolates were collected from a medical center (comprising 2 branches in Northern Taiwan during 2009–2012. AmpC β-lactamase genes were analyzed through a polymerase chain reaction using plasmid DNA templates and gene sequencing. The genetic relationships of the isolates were typed using pulsed-field gel electrophoresis following the digestion of intact genomic DNA by using XbaI. Results: Three enterobacterial isolates (one Escherichia coli and 2 Klebsiella pneumoniae were obtained from 3 hospitalized patients. All 3 isolates were resistant or intermediately susceptible to all β-lactams, and exhibited reduced susceptibility to carbapenems. These 3 isolates expressed a novel AmpC β-lactamase, designated DHA-23, approved by the curators of the Lahey website. DHA-23 differs from DHA-1 and DHA-6 by one amino acid substitution (Ser245Ala, exhibiting 2 amino acid changes compared with DHA-7 and DHA-Morganella morganii; 3 amino acid changes compared with DHA-3; 4 amino acid changes compared with DHA-5; and 8 amino acid changes compared with DHA-2 (> 97% identity. This AmpC β-lactamase is inducible using a system involving ampR. Conclusion: This is the first report to address DHA-23, a novel AmpC β-lactamase. DHA-type β-lactamases are continuous threat in Taiwan.

  4. Emergence of serotype K1 Klebsiella pneumoniae ST23 strains co-producing the plasmid-mediated AmpC beta-lactamase DHA-1 and an extended-spectrum beta-lactamase in Korea

    Directory of Open Access Journals (Sweden)

    Hae Suk Cheong

    2016-11-01

    Full Text Available Abstract Background Serotype K1 Klebsiella pneumoniae has emerged as an important community pathogen causing various infections, including liver abscesses. Although serotype K1 K. pneumoniae community isolates have been reported as susceptible to most classes of antimicrobial agents, a few cases of infection caused by extended-spectrum beta-lactamase (ESBL-producing serotype K1 K. pneumoniae have recently been reported in Asian countries. We identified three ESBL-producing strains of serotype K1 K. pneumoniae and conducted a molecular characterization of their drug resistance. Methods Three ESBL-producing serotype K1 K. pneumoniae ST23 strains were identified from strains in the Asian Bacterial Bank. Antimicrobial susceptibility testing was performed using the broth microdilution method, and ESBL production was tested by the double-disk synergy test and a confirmatory test. PCR was performed to detect the genes for plasmid-mediated ESBL and AmpC beta-lactamases. Results All three strains were resistant to cefotaxime, ceftazidime, and piperacillin/tazobactam, and all were determined to be ESBL-producers. No known ESBL genes, including bla SHV, bla TEM, bla CTX-M, bla GES, bla PER, and bla VEB, were detected among the three strains. Of all plasmid-mediated AmpC beta-lactamase (PAB genes, including bla DHA-1, bla CMY, bla FOX, and bla MOX, the bla DHA-1 gene was detected in two of the strains. The PFGE patterns revealed that the two isolates carrying bla DHA-1 were closely related (84% similarity. Conclusions No ESBL genes were detected among three ESBL-producing serotype K1 K. pneumoniae ST23 strains. Two strains contained the PAB gene bla DHA-1. The emergence of resistant strains of community-origin serotype K1 K. pneumoniae has important implications for effective treatment and infection control practices.

  5. 尿路分离大肠埃希菌耐药性及喹诺酮类药物耐药株危险因素病例对照研究%The drug resistance of Escherichia coli isolated from urinary tract infection and risk factors of quinolone resistance strains

    Institute of Scientific and Technical Information of China (English)

    张昭勇; 张吉才; 杜毅

    2013-01-01

    Objective To analyze the drug resistance of Escherichia coli isolated from urinary tract infection and risk factors of quinolone resistance strains.Methods A total of 705 cases (strains) with Escherichia coli drug resistance isolated from urine specimens were divided into quinolone sensitive group [474 cases(strains)] and quinolone resistance group [231 cases(strains)].The risk factors of the quinolone resistance strains were analyzed.Results The sensitivity rate of amoxicillin/clavulanic acid,cefalotin,ceftazidime,aztreonam,piperacillin,amikacin,compound sulfamethoxazole,ciprofloxacin,gentamicin,levofloxacin,cefepime in quinolone resistance group was higher than that in quinolone sensitive group [50.2%(238/474) vs.78.8%(182/231),11.6%(55/474) vs.48.5%(112/231),17.9%(85/474) vs.63.2%(146/231),15.0%(71/474) vs.57.6%(133/231),3.2%(15/474) vs.27.7%(64/231),80.8%(383/474)vs.93.1%(215/231),16.0%(76/474) vs.49.8%(115/231),0 vs.100.0%(231/231),32.5% (154/474)vs.70.6% (163/231),3.8% (18/474) vs.98.7% (228/231),18.6% (88/474) vs.63.2% (146/231),P <0.05].Logistic regression analysis showed history of using the third generation cephalosporins and quinolones,urinary drainage and bacterium producing extra-broad spectrum beta-lactamase was independent risk factor for quinolone resistance Escherichia coli (P < 0.05).Conclusions The epidemic of quinolone resistance Escherichia coli isolated from urine specimens is extremely serious.The quinolone resistance is strong,and infection patients have a high medical cost and average length of stay.The quinolone resistance Escherichia coli infection has multiple independent risk factors.To strengthen the control of the independent risk factors can effectively prevent quinolone resistance strains infection spread.%目的 分析尿路感染大肠埃希菌耐药性及喹诺酮类药物耐药株感染危险因素.方法 监测705例(株)尿路感染大肠埃希菌的耐

  6. Photoprocesses in quinolone substituted

    Science.gov (United States)

    Vasilyeva, N. Y.; Vusovich, O. V.

    2002-03-01

    In the present work the analysis of the possible ways of energy degradation of electron excited states of 4-methyl-7- hydxyquinolone-2 (Q) and its protolytic species is presented (Figure 1); a ratio of radiative and nonradiative channels of deactivation of energy of electronic excitation is established; constants of photophysical processes (internal and intercrossing conversion), proceeding after act of absorption of light are designed. Study of exited state intramolecular proton transfer (ESIPT) in quinolones is interesting as a source of information on the relative importance of these processes in the photophysics and photochemistry of such molecular systems.

  7. Antimicrobial resistance of Salmonella serovars isolated from beef at retail markets in the north Vietnam.

    Science.gov (United States)

    Thai, Truong Ha; Hirai, Takuya; Lan, Nguyen Thi; Shimada, Akinori; Ngoc, Pham Thi; Yamaguchi, Ryoji

    2012-09-01

    Approximately 39.9% (63/158) of beef samples collected from retail markets in Hanoi from January to June 2009 were Salmonella-positive. Nine Salmonella serovars, Anatum (28.6%), Rissen (25.4%), Weltevreden (12.7%), Typhimurium (7.9%), Derby (7.9%), Lexington (7.9%), Dublin (4.6%), Newport (3.2%) and London (1.8%), were identified. Thirty-seven (58.7%) of the 63 Salmonella isolates were resistant to at least one antimicrobial tested, of which 29 (46%) isolates showed multidrug resistance (MDR). The isolates were commonly resistant to tetracycline (46.0%), sulphonamide (39.7%), ampicilline (31.7%), streptomycin (30.2%), trimethoprim (28.6%), kanamycin (28.6%) and chloramphenicol (22.2%). Fourteen (bla(TEMV), bla(OXA-1), aadA1, aadA2, sul1, tetA, tetB, tetG, cmlA1, floR, dfrA1, dfrA12, aac (3)-IV and aphA1-1AB) out of 22 antimicrobial resistance genes were detected by PCR from the resistant isolates. The catA1, Kn, blaPSE-1 genes and plasmid-mediated quinolones resistance (PMQR) genes such as qnrA, qnrB, qnrS, qepA and acc (6')-ib-cr were not detected. Mutations in the gyrA gene leading to the amino acid changes Ser83Phe and/or Asp87Asn were found in 6 out of the 11 quinolone-resistant isolates. The data revealed that multidrug resistant Salmonella strains were widely distributed in north Vietnam via the food chain and might contain multiple genes specifying identical resistant phenotypes. Thus, continuous studies are necessary to clarify the mechanisms of MDR in Salmonella and its spread in the livestock market.

  8. High prevalence of plasmid-mediated 16S rRNA methylase gene rmtB among Escherichia coli clinical isolates from a Chinese teaching hospital

    Directory of Open Access Journals (Sweden)

    Zhang Xue-qing

    2010-06-01

    transposon, Tn3, was located upstream of the rmtB. Nineteen clonal patterns were obtained by PFGE, with type H representing the prevailing pattern. Conclusion A high prevalence of plasmid-mediated rmtB gene was found among clinical E. coli isolates from a Chinese teaching hospital. Both horizontal gene transfer and clonal spread were responsible for the dissemination of the rmtB gene.

  9. Enhanced resistance to fluoroquinolones in laboratory-grown mutants & clinical isolates of Shigella due to synergism between efflux pump expression & mutations in quinolone resistance determining region

    Directory of Open Access Journals (Sweden)

    Neelam Taneja

    2015-01-01

    Full Text Available Background & objectives: There is a worldwide emergence of fluoroquinolone resistance in Shigella species. To understand the molecular mechanisms associated with fluoroquinolone resistance, naturally occurring fluoroquinolone-resistant strains and laboratory-induced spontaneous mutants of Shigella spp. were used and the relative contributions of acrAB-tolC efflux pumps, gyrase and topoisomerase target gene mutations towards fluoroquinolone resistance were determined. Methods: Eight Shigella flexneri and six S. dysenteriae clinical isolates were studied. Three consecutive mutants resistant to ciprofloxacin for S. flexneri SFM1 (≥0.25 µg/ml, SFM2 (≥4 µg/ml and SFM3 (≥32 µg/ml were selected in 15 steps from susceptible isolates by serial exposure to increasing concentrations of nalidixic acid and ciprofloxacin. Similarly, two mutants for S. dysenteriae SDM1 (≥0.25 µg/ml and SDM2 (≥4 µg/ml were selected in eight steps. After PCR amplification sequence analyses of gyrase and topoisomerase target genes were performed. Expression of efflux genes acrA, acrB, acrR and tolC was measured using real-time PCR. Results: Mutations were observed in gyrA Ser [83]→Leu, Asp [87]→Asn/Gly, Val [196]→Ala and in parC Phe [93]→Val, Ser [80]→Ile, Asp [101]→Glu and Asp [110]→Glu. Overall, acrA and acrB overexpression was associated with fluoroquinolone resistance ( p0 <0.05; while tolC and acrR expression levels did not. Interpretation & conclusions: Fluoroquinolone resistance in Shigella spp. is the end product of either a single or a combination of mutations in QRDRs and/ or efflux activity. Novel polymorphisms were observed at Val [196]→Ala in gyrA in clinical isolates and Phe [93]→Val, Asp [101]→Glu, Asp [110]→Glu and in parC in majority of laboratory-grown mutants.

  10. Microbiological characterization of plasmid-mediated AmpC ß-lactamases and E. coli hyperproducers: how and why ?

    Directory of Open Access Journals (Sweden)

    Annibale Raglio

    2010-03-01

    Full Text Available The aim of this study is the evaluation of phenotypic method for the detection of plasmid-mediated AmpC producing Enterobacteriaceae by agar diffusion.We developed a phenotypic method with double disk test (CLSI and evaluation of synergism between Cloxacillin and/or Boronic Acid with cefotaxime and ceftazidime and cefepime with amoxicillin/clavulanic acid. As reference method for AmpC detection we used a multiplex PCR according to Perez-Perez. Among 7476 Enterobacteriaceae we detected 45 strains: 37 (82.2% plasmid-mediated AmpC producers, 6 (13.3% E. coli hyperproducers and 2 E. coli (4.5% positive for both.The AmpC phenotypic test was positive for all the isolates, showing a typical ghost zone between cloxacillin and cephalosporins or boronic acid and cephalosporins.The AmpC multiplex PCR confirmed that 28 P. mirabilis and 7 E. coli harboured a gene belonging to the bla-CMY-LAT family. Sequencing defined the presence of CMY-16 in all P. mirabilis, CMY-2 in E. coli, DHA-1 in 3 K. pneumoniae and FOX in 1 K. pneumoniae and allowed us to identify eight strains as E. coli hyperproducer: six E. coli yielded no amplicon and 2 were also producer of CMY-2. In this study the phenotypic method showed a sensitivity and a specificity of 100%.Waiting for the indication of international authorities, we think this phenotypic screening method could be useful in the routine of microbiological laboratories.

  11. The determination of plamid-mediated qnr gene in quinolone-resistant Shigella%氟喹诺酮耐药志贺菌中质粒介导qnr基因的检测

    Institute of Scientific and Technical Information of China (English)

    汪雅萍; 应春妹; 张灏旻; 叶杨芹; 于嘉屏

    2011-01-01

    目的 检测志贺菌对氟喹诺酮抗菌药物的耐药情况,探讨氟喹诺酮耐药与志贺菌携带质粒介导qnr基因的关系.方法 用纸片扩散法对100株志贺菌(福氏志贺菌50株,宋内志贺菌50株)进行耐药性检测,聚合酶链反应(PCR)检测志贺菌质粒介导qnr基因并进行DNA测序,分析qnr基因的存在与药敏结果的关系.结果 100株志贺菌中有9株检出qnr基因,检出率为9% (9/100),福氏志贺菌为4% (2/50),宋内志贺菌为14%(7/50);qnr基因阳性菌株对氧氟沙星的耐药率(11.1%)高于阴性菌株(5.5%),但差异无统计学意义.qnr基因阳性菌株对5种氟喹诺酮药物的抑菌圈中位数比较均缩小.结论宋内志贺菌质粒介导氟喹诺酮耐药qnr基因的携带率明显高于福氏志贺菌;志贺菌若携带质粒介导qnr基因则会导致对氟喹诺酮药物的敏感性下降.%Objective To investigate the quinolone-resistance of Shigella isolates and its relationship with the plamid-mediated qnr gene. Methods A total of 100 Shigella isolates were collected. SO isolates were ShigeUa flexneri, and 50 isolates were Shigella sonnei. The drug resistance was determined by disc diffusion method. The qnr gene was detected by polymerase chain reaction ( PCR). The qnr gene segments were amplified and sequenced to analyze the correlation between quinolone-resistance and the presence of qnr gene. Results The qnr gene was identified in 9 (9% )of the 100 ShigeUa isolates,2 (4% ) of the 50 Shigella flexneri and 7 ( 14% ) of the 50 Shigella sonnei. The resistance rate of ofloxacin in qnr positive isolates(11. 1% ) was higher than that in qnr negative isolates(5.5% ) , but there was no statistical significance. The median diameters of 5 quinolone inhibition zones of the isolates with qnr gene were smaller than those without qnr gene. Conclusions The plamid-mediated qnr gene in Shigella sonnei isolates is more than that in Shigella flexneri isolates. The plamid-mediated qnr

  12. Prevalence of gyrA Mutations in Nalidixic Acid-Resistant Strains of Salmonella Enteritidis Isolated from Humans, Food, Chickens, and the Farm Environment in Brazil.

    Science.gov (United States)

    Campioni, Fábio; Souza, Roberto Antonio; Martins, Vinicius Vicente; Stehling, Eliana Guedes; Bergamini, Alzira Maria Morato; Falcão, Juliana Pfrimer

    2016-08-25

    Salmonella Enteritidis strains that are resistant to nalidixic acid and exhibit reduced susceptibility to fluoroquinolones have been increasing worldwide. In Brazil, few studies have been conducted to elucidate the quinolone resistance mechanisms of S. Enteritidis strains. This study analyzed the profile of gyrA, gyrB, parC, and parE mutations and plasmid-mediated quinolone resistance (PMQR) mechanisms in S. Enteritidis Nal(R) strains isolated in Brazil. Moreover, the minimum inhibitory concentrations (MICs) of ciprofloxacin were evaluated in 84 Nal(R) strains and compared with 20 Nal(S) strains. The mutation profiles of the gyrA gene were accessed by high-resolution melting analysis and gyrB, parC, and parE by quinolone resistance-determining region sequencing. The MICs of ciprofloxacin were accessed with Etest(®). The strains were divided into five gyrA melting profiles. The Nal(R) strains exhibited the following amino acid substitutions: Ser97→Pro, Ser83→Phe, Asp87→Asn, or Asp87→Tyr. The average MICs of ciprofloxacin was 0.006 μg/ml in the Nal(S) and 0.09 μg/ml in the Nal(R) strains. No points of mutation were observed in the genes gyrB, parC, and parE. The qnrB gene was found in two strains. In conclusion, the reduced susceptibility to ciprofloxacin observed in Nal(R) strains may cause treatment failures once this drug is commonly used to treat Salmonella infections. Moreover, this reduced susceptibility in these Brazilian strains was provided by target alteration of gene gyrA and not by mobile elements, such as resistance plasmids.

  13. Molecular mechanism of the qnrA gene-mediated quionlone resistance in Gram-negative bacteria

    Institute of Scientific and Technical Information of China (English)

    SONG SHENG XIAO; JIAN LU; WEI YUAN WU; CHUANG HONG WU; LI XIA WEN

    2007-01-01

    To explore the prevalence of the plasmid-mediated quinolone resistance gene qnrA in Gramnegative bacteria and to investigate its molecular genetic background and resistance profile in isolates harboring this gene, a total of 629 nalidixic acid-resistant isolates of non-repetitive Gram-negative bacteria were collected from clinical specimens between April 2004 and April 2006 and these isolates were screened for qnrA gene by PCR using specific primers combined with DNA sequencing. The extended spectnan β-lactamase (ESBL) or AmpC-producing isolates were distinguished by the phenotypic confirmatory test combined with DNA sequencing, and the antibiotics susceptibility test for qnrA-positive isolates was carried out by Kirby-Bauer and E-test method. To detect the location of the qnrA gene, plasmid conjugation and Southern hybridization were performed and the integron structure containing the qnrA gene was cloned by PCR strategy and sequenced by primer walking. It was demonstrated that the incidence of the qnrA-positive strains in nalidixic acid-resistant bacteria was 1.9% (12/629), in which the detection rates for Klebiesiella pneumoniae. Enterobacter cloacae, Enterobacter aerogenes,Citrobacter freundii and Salmonella choeraesuis were 2.2% (3/138), 17. 1% (6/35), 9. 1%(1/11), 12.5% (1/8), and 14.3% (1/7), respectively. The qnrA gene was found to be embedded in the complex su/1-type integron located on plasmids with varied size (80-180 kb). Among them, 4qnrA-positive isolates carried integron In37 and 8 isolates carried a novel integron, temporarily designated as InX. All the qnrA-positive isolates were ESBL-producing and transferable for the multi-drug resistance. It is concluded that the plasmid-mediated drug-resistance mechanism exists in the quinolone resistant strains of isolates from hospitals in Guangdong area, but the incidence was rather low. Nevertheless, it is still possible that the horizontal transfer of the resistant qnrA gene might lead to the spreading of

  14. Brief communication: detection of clinical Klebsiella pneumoniae isolates from China containing transferable quinolone resistance determinants exhibiting resistance to both aminoglycoside and β-lactams.

    Science.gov (United States)

    Xue, Xinying; Pan, Lei; Zhang, Naxin; Liu, Yuxia; Luo, Yanping; Zhou, Guang; Guan, Xizhou

    2014-01-01

    Though aminoglycosides are routinely used clinically as antimicrobial agents for the treatment of severe infections due to Klebsiella pneumoniae, resistance to the same is an increasing problem. One such resistance mechanism is the production of 16S rRNA methylases. The objective of the current study was to investigate the prevalence and molecular epidemology of 16S rRNA methylase genes among 43 K. pneumoniae isolates (each of which had at least one PQMR gene and ciprofloxacin minimum inhibitory concentration greater than 0.25) recovered from nine tertiary hospitals in China. Our results suggest great genetic variation in terms of 16S rRNA methylase gene of K. pneumoniae hosts containing at least one PQMR gene. This further reinforces the clinical and systemic urgency required to characterize and block their transmission routes.

  15. Presence of multi-drug resistant pathogenic Escherichia coli in the San Pedro River located in the State of Aguascalientes, Mexico.

    Science.gov (United States)

    Ramírez Castillo, Flor Y; Avelar González, Francisco J; Garneau, Philippe; Márquez Díaz, Francisco; Guerrero Barrera, Alma L; Harel, Josée

    2013-01-01

    Contamination of surface waters in developing countries is a great concern. Treated and untreated wastewaters have been discharged into rivers and streams, leading to possible waterborne infection outbreaks and may represent a significant dissemination mechanism of antibiotic resistance genes. In this study, the water quality of San Pedro River, the main river and pluvial collector of the Aguascalientes State, Mexico was assessed. Thirty sample locations were tested throughout the River. The main physicochemical parameters of water were evaluated. Results showed high levels of fecal pollution as well as inorganic and organic matter abundant enough to support the heterotrophic growth of microorganisms. These results indicate poor water quality in samples from different locations. One hundred and fifty Escherichia coli were collected and screened by PCR for several virulence genes. Isolates were classified as either pathogenic (n = 91) or commensal (n = 59). The disc diffusion method was used to determine antimicrobial susceptibility to 13 antibiotics. Fifty-two percent of the isolates were resistant to at least one antimicrobial agent and 30.6% were multi-resistant. Eighteen E. coli strains were quinolone resistant of which 16 were multi-resistant. Plasmid-mediated quinolone resistance (PMQR) genes were detected in 12 isolates. Mutations at the Ser-83→Leu and/or Asp-87→Asn in the gyrA gene were detected as well as mutations at the Ser-80→Ile in parC. An E. coli microarray (Maxivirulence V 3.1) was used to characterize the virulence and antimicrobial resistance genes profiles of the fluoroquinolone-resistant isolates. Antimicrobial resistance genes such as bla TEM, sulI, sulII, dhfrIX, aph3 (strA), and tet (B) as well as integrons were found in fluoroquinolone (FQ) resistance E. coli strains. The presence of potential pathogenic E. coli and antibiotic resistance in San Pedro River such as FQ resistant E. coli could pose a potential threat to human and animal

  16. Antipneumococcal activity of DW-224a, a new quinolone, compared to those of eight other agents.

    Science.gov (United States)

    Kosowska-Shick, Klaudia; Credito, Kim; Pankuch, Glenn A; Lin, Gengrong; Bozdogan, Bülent; McGhee, Pamela; Dewasse, Bonifacio; Choi, Dong-Rack; Ryu, Jei Man; Appelbaum, Peter C

    2006-06-01

    DW-224a is a new broad-spectrum quinolone with excellent antipneumococcal activity. Agar dilution MIC was used to test the activity of DW-224a compared to those of penicillin, ciprofloxacin, levofloxacin, gatifloxacin, moxifloxacin, gemifloxacin, amoxicillin-clavulanate, cefuroxime, and azithromycin against 353 quinolone-susceptible pneumococci. The MICs of 29 quinolone-resistant pneumococci with defined quinolone resistance mechanisms against seven quinolones and an efflux mechanism were also tested. DW-224a was the most potent quinolone against quinolone-susceptible pneumococci (MIC(50), 0.016 microg/ml; MIC(90), 0.03 microg/ml), followed by gemifloxacin, moxifloxacin, gatifloxacin, levofloxacin, and ciprofloxacin. beta-Lactam MICs rose with those of penicillin G, and azithromycin resistance was seen mainly in strains with raised penicillin G MICs. Against the 29 quinolone-resistant strains, DW-224a had the lowest MICs (0.06 to 1 microg/ml) compared to those of gemifloxacin, clinafloxacin, moxifloxacin, gatifloxacin, levofloxacin, and ciprofloxacin. DW-224a at 2x MIC was bactericidal after 24 h against eight of nine strains tested. Other quinolones gave similar kill kinetics relative to higher MICs. Serial passages of nine strains in the presence of sub-MIC concentrations of DW-224a, moxifloxacin, levofloxacin, ciprofloxacin, gatifloxacin, gemifloxacin, amoxicillin-clavulanate, cefuroxime, and azithromycin were performed. DW-224a yielded resistant clones similar to moxifloxacin and gemifloxacin but also yielded lower MICs. Azithromycin selected resistant clones in three of the five parents tested. Amoxicillin-clavulanate and cefuroxime did not yield resistant clones after 50 days.

  17. Epidemiology, Clinical Presentation, Laboratory Diagnosis, Antimicrobial Resistance, and Antimicrobial Management of Invasive Salmonella Infections

    Science.gov (United States)

    Sjölund-Karlsson, Maria; Gordon, Melita A.; Parry, Christopher M.

    2015-01-01

    SUMMARY Salmonella enterica infections are common causes of bloodstream infection in low-resource areas, where they may be difficult to distinguish from other febrile illnesses and may be associated with a high case fatality ratio. Microbiologic culture of blood or bone marrow remains the mainstay of laboratory diagnosis. Antimicrobial resistance has emerged in Salmonella enterica, initially to the traditional first-line drugs chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole. Decreased fluoroquinolone susceptibility and then fluoroquinolone resistance have developed in association with chromosomal mutations in the quinolone resistance-determining region of genes encoding DNA gyrase and topoisomerase IV and also by plasmid-mediated resistance mechanisms. Resistance to extended-spectrum cephalosporins has occurred more often in nontyphoidal than in typhoidal Salmonella strains. Azithromycin is effective for the management of uncomplicated typhoid fever and may serve as an alternative oral drug in areas where fluoroquinolone resistance is common. In 2013, CLSI lowered the ciprofloxacin susceptibility breakpoints to account for accumulating clinical, microbiologic, and pharmacokinetic-pharmacodynamic data suggesting that revision was needed for contemporary invasive Salmonella infections. Newly established CLSI guidelines for azithromycin and Salmonella enterica serovar Typhi were published in CLSI document M100 in 2015. PMID:26180063

  18. Antibiotic resistance genes in surface water of eutrophic urban lakes are related to heavy metals, antibiotics, lake morphology and anthropic impact.

    Science.gov (United States)

    Yang, Yuyi; Xu, Chen; Cao, Xinhua; Lin, Hui; Wang, Jun

    2017-08-01

    Urban lakes are impacted by heavy human activities and represent potential reservoirs for antibiotic resistance genes. In this study, six urban lakes in Wuhan, central China were selected to analyze the distribution of sulfonamide resistance (sul) genes, tetracycline resistance (tet) genes and quinolone resistance (qnr) genes and their relationship with heavy metals, antibiotics, lake morphology and anthropic impact. sul1 and sul2 were detected in all six lakes and dominated the types of antibiotic resistance genes, which accounted for 86.28-97.79% of the total antibiotic resistance gene abundance. For eight tested tet genes, antibiotic efflux pumps (tetA, tetB, tetC, and tetG) genes were all observed in six lakes and had higher relative abundance than ribosomal protection protein genes (tetM and tetQ). For 4 plasmid mediated quinolone resistance genes, only qnrD is found in all six lakes. The class I integron (intI1) is also found to be a very important media for antibiotic resistance gene propagation in urban lakes. The results of redundancy analysis and variation partitioning analysis showed that antibiotic and co-selection with heavy metals were the major factors driving the propagation of antibiotic resistance genes in six urban lakes. The heavily eutrophic Nanhu Lake and Shahu Lake which located in a high density building area with heavy human activities had the higher relative abundance of total antibiotic resistance genes. Our study could provide a useful reference for antibiotic resistance gene abundance in urban lakes with high anthropic impact.

  19. The mechanism of Quinolone resistance and its research progress%喹诺酮类抗菌药的耐药机制及其研究进展

    Institute of Scientific and Technical Information of China (English)

    林惊世; 顾晟琰; 蒋震媚

    2012-01-01

    喹诺酮类(quinolones)药物是人工合成的含4-喹诺酮基本结构,对细菌DNA螺旋酶(DNA gyrase)具有选择性抑制作用,是一种DNA旋转酶抑制剂,干扰DNA超螺旋结构的解旋,从而阻碍DNA的复制,而呈现杀菌作用,故在分类上属慢效杀菌剂.笔者通过检索、查阅相应文献,综合归纳了喹诺酮类抗菌药物的耐药机制及其研究进展.

  20. Antibiotics, Antibiotic Resistance Genes, and Bacterial Community Composition in Fresh Water Aquaculture Environment in China.

    Science.gov (United States)

    Xiong, Wenguang; Sun, Yongxue; Zhang, Tong; Ding, Xueyao; Li, Yafei; Wang, Mianzhi; Zeng, Zhenling

    2015-08-01

    Environmental antibiotic resistance has drawn increasing attention due to its great threat to human health. In this study, we investigated concentrations of antibiotics (tetracyclines, sulfonamides and (fluoro)quinolones) and abundances of antibiotic resistance genes (ARGs), including tetracycline resistance genes, sulfonamide resistance genes, and plasmid-mediated quinolone resistance genes, and analyzed bacterial community composition in aquaculture environment in Guangdong, China. The concentrations of sulfametoxydiazine, sulfamethazine, sulfamethoxazole, oxytetracycline, chlorotetracycline, doxycycline, ciprofloxacin, norfloxacin, and enrofloxacin were as high as 446 μg kg(-1) and 98.6 ng L(-1) in sediment and water samples, respectively. The relative abundances (ARG copies/16S ribosomal RNA (rRNA) gene copies) of ARGs (sul1, sul2, sul3, tetM, tetO, tetW, tetS, tetQ, tetX, tetB/P, qepA, oqxA, oqxB, aac(6')-Ib, and qnrS) were as high as 2.8 × 10(-2). The dominant phyla were Proteobacteria, Bacteroidetes, and Firmicutes in sediment samples and Proteobacteria, Actinobacteria and Bacteroidetes in water samples. The genera associated with pathogens were also observed, such as Acinetobacter, Arcobacter, and Clostridium. This study comprehensively investigated antibiotics, ARGs, and bacterial community composition in aquaculture environment in China. The results indicated that fish ponds are reservoirs of ARGs and the presence of potential resistant and pathogen-associated taxonomic groups in fish ponds might imply the potential risk to human health.

  1. Characterization of Campylobacter jejuni DNA gyrase as the target of quinolones.

    Science.gov (United States)

    Changkwanyeun, Ruchirada; Usui, Masaru; Kongsoi, Siriporn; Yokoyama, Kazumasa; Kim, Hyun; Suthienkul, Orasa; Changkaew, Kanjana; Nakajima, Chie; Tamura, Yutaka; Suzuki, Yasuhiko

    2015-08-01

    Quinolones have long been used as the first-line treatment for Campylobacter infections. However, an increased resistance to quinolones has raised public health concerns. The development of new quinolone-based antibiotics with high activity is critical for effective, as DNA gyrase, the target of quinolones, is an essential enzyme for bacterial growth in several mechanisms. The evaluation of antibiotic activity against Campylobacter jejuni largely relies on drug susceptibility tests, which require at least 2 days to produce results. Thus, an in vitro method for studying the activity of quinolones against the C. jejuni DNA gyrase is preferred. To identify potent quinolones, we investigated the interaction of C. jejuni DNA gyrase with a number of quinolones using recombinant subunits. The combination of purified subunits exhibited DNA supercoiling activity in an ATP dependent manner. Drug concentrations that inhibit DNA supercoiling by 50% (IC50s) of 10 different quinolones were estimated to range from 0.4 (sitafloxacin) to >100 μg/mL (nalidixic acid). Sitafloxacin showed the highest inhibitory activity, and the analysis of the quinolone structure-activity relationship demonstrated that a fluorine atom at R-6 might play the important role in the inhibitory activity against C. jejuni gyrase. Measured quinolone IC50s correlated well with minimum inhibitory concentrations (R = 0.9943). These suggest that the in vitro supercoiling inhibition assay on purified recombinant C. jejuni DNA gyrase is a useful and predictive technique to monitor the antibacterial potency of quinolones. And furthermore, these data suggested that sitafloxacin might be a good candidate for clinical trials on campylobacteriosis.

  2. Correlation of Mutation Patterns in gyrA and parC Genes in Ureaplasma Urealyticum Isolates with Quinolones Resistance%gyrA和parC基因突变与解脲支原体喹诺酮类药物耐药相关性研究

    Institute of Scientific and Technical Information of China (English)

    王春燕; 杜江; 吴森林; 孙爱华

    2012-01-01

    Objective To analyze mutations in the quinolone -resistance - determining - region ( QRDR) within genes of gyrA and parC patterns in gyrA and parC genes and quinolones resistance in ureaplasma urealyticum(Uu) isolates. Methods Mycoplasma detection kits were used to culture and identificate mycoplasma as well as drug sensitivity. PCR and DNA sequencing were conducted to analyze QRDR associated genes of gyrA and parC in 42 isolates. Results Only 1 isolate susceptible to all quinolones. Fourty - one isolates showed varying degree resistance to at least one kind of quinolones. Sequencing analysis of gyrA and parC revealed that the susceptible i-solate and 1 resistance isolate had no mutation, Fourty resistance isolates had mutation of D112E and/or S83L in GyrA and ParC. Conclusion Three quinolones should not be routine therapy for ureaplasma urealyticum infections. Mutations in gyrA and parC genes play an important role in the development of quinolones resistance in ureaplasma urealyticum.%目的 探讨解脲支原体gyrA和parC基因喹诺酮耐药决定区(QRDR)突变与喹诺酮类药物耐药的相关性.方法 用支原体培养、鉴定和药敏一体化试剂盒分离获得42株解脲支原体并检测对3种喹诺酮类药物的耐药性,同时PCR法扩增临床分离株的gyrA和parC基因喹诺酮耐药决定区并进行测序分析.结果 对3种喹诺酮均敏感1株,41株至少对1种药物呈现不同程度耐药.gyrA和parC基因喹诺酮耐药决定区测序发现上述敏感株和1株耐药株不发生突变,其余40株耐药株gyrA和parC基因发生D112E和(或)S83L突变.结论 3种喹诺酮类药物耐药均较严重,已不适合作为临床推荐用药,解脲支原体gyrA和parC基因喹诺酮耐药决定区突变与耐药密切相关.

  3. Metagenomic analysis reveals that bacteriophages are reservoirs of antibiotic resistance genes.

    Science.gov (United States)

    Subirats, Jéssica; Sànchez-Melsió, Alexandre; Borrego, Carles M; Balcázar, José Luis; Simonet, Pascal

    2016-08-01

    A metagenomics approach was applied to explore the presence of antibiotic resistance genes (ARGs) in bacteriophages from hospital wastewater. Metagenomic analysis showed that most phage sequences affiliated to the order Caudovirales, comprising the tailed phage families Podoviridae, Siphoviridae and Myoviridae. Moreover, the relative abundance of ARGs in the phage DNA fraction (0.26%) was higher than in the bacterial DNA fraction (0.18%). These differences were particularly evident for genes encoding ATP-binding cassette (ABC) and resistance-nodulation-cell division (RND) proteins, phosphotransferases, β-lactamases and plasmid-mediated quinolone resistance. Analysis of assembled contigs also revealed that blaOXA-10, blaOXA-58 and blaOXA-24 genes belonging to class D β-lactamases as well as a novel blaTEM (98.9% sequence similarity to the blaTEM-1 gene) belonging to class A β-lactamases were detected in a higher proportion in phage DNA. Although preliminary, these findings corroborate the role of bacteriophages as reservoirs of resistance genes and thus highlight the necessity to include them in future studies on the emergence and spread of antibiotic resistance in the environment. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  4. TLA-1: a new plasmid-mediated extended-spectrum beta-lactamase from Escherichia coli.

    Science.gov (United States)

    Silva, J; Aguilar, C; Ayala, G; Estrada, M A; Garza-Ramos, U; Lara-Lemus, R; Ledezma, L

    2000-04-01

    Escherichia coli R170, isolated from the urine of an infected patient, was resistant to expanded-spectrum cephalosporins, aztreonam, ciprofloxacin, and ofloxacin but was susceptible to amikacin, cefotetan, and imipenem. This particular strain contained three different plasmids that encoded two beta-lactamases with pIs of 7.0 and 9.0. Resistance to cefotaxime, ceftazidime, aztreonam, trimethoprim, and sulfamethoxazole was transferred by conjugation from E. coli R170 to E. coli J53-2. The transferred plasmid, RZA92, which encoded a single beta-lactamase, was 150 kb in length. The cefotaxime resistance gene that encodes the TLA-1 beta-lactamase (pI 9.0) was cloned from the transconjugant by transformation to E. coli DH5alpha. Sequencing of the bla(TLA-1) gene revealed an open reading frame of 906 bp, which corresponded to 301 amino acid residues, including motifs common to class A beta-lactamases: (70)SXXK, (130)SDN, and (234)KTG. The amino acid sequence of TLA-1 shared 50% identity with the CME-1 chromosomal class A beta-lactamase from Chryseobacterium (Flavobacterium) meningosepticum; 48.8% identity with the VEB-1 class A beta-lactamase from E. coli; 40 to 42% identity with CblA of Bacteroides uniformis, PER-1 of Pseudomonas aeruginosa, and PER-2 of Salmonella typhimurium; and 39% identity with CepA of Bacteroides fragilis. The partially purified TLA-1 beta-lactamase had a molecular mass of 31.4 kDa and a pI of 9.0 and preferentially hydrolyzed cephaloridine, cefotaxime, cephalothin, benzylpenicillin, and ceftazidime. The enzyme was markedly inhibited by sulbactam, tazobactam, and clavulanic acid. TLA-1 is a new extended-spectrum beta-lactamase of Ambler class A.

  5. TLA-1: a New Plasmid-Mediated Extended-Spectrum β-Lactamase from Escherichia coli

    Science.gov (United States)

    Silva, J.; Aguilar, C.; Ayala, G.; Estrada, M. A.; Garza-Ramos, U.; Lara-Lemus, R.; Ledezma, L.

    2000-01-01

    Escherichia coli R170, isolated from the urine of an infected patient, was resistant to expanded-spectrum cephalosporins, aztreonam, ciprofloxacin, and ofloxacin but was susceptible to amikacin, cefotetan, and imipenem. This particular strain contained three different plasmids that encoded two β-lactamases with pIs of 7.0 and 9.0. Resistance to cefotaxime, ceftazidime, aztreonam, trimethoprim, and sulfamethoxazole was transferred by conjugation from E. coli R170 to E. coli J53-2. The transferred plasmid, RZA92, which encoded a single β-lactamase, was 150 kb in length. The cefotaxime resistance gene that encodes the TLA-1 β-lactamase (pI 9.0) was cloned from the transconjugant by transformation to E. coli DH5α. Sequencing of the blaTLA-1 gene revealed an open reading frame of 906 bp, which corresponded to 301 amino acid residues, including motifs common to class A β-lactamases: 70SXXK, 130SDN, and 234KTG. The amino acid sequence of TLA-1 shared 50% identity with the CME-1 chromosomal class A β-lactamase from Chryseobacterium (Flavobacterium) meningosepticum; 48.8% identity with the VEB-1 class A β-lactamase from E. coli; 40 to 42% identity with CblA of Bacteroides uniformis, PER-1 of Pseudomonas aeruginosa, and PER-2 of Salmonella typhimurium; and 39% identity with CepA of Bacteroides fragilis. The partially purified TLA-1 β-lactamase had a molecular mass of 31.4 kDa and a pI of 9.0 and preferentially hydrolyzed cephaloridine, cefotaxime, cephalothin, benzylpenicillin, and ceftazidime. The enzyme was markedly inhibited by sulbactam, tazobactam, and clavulanic acid. TLA-1 is a new extended-spectrum β-lactamase of Ambler class A. PMID:10722503

  6. Plasmid-mediated biodegradation of the anionic surfactant sodium dodecyl sulphate, by Pseudomonas aeruginosa S7.

    Science.gov (United States)

    Yeldho, Deepthi; Rebello, Sharrel; Jisha, M S

    2011-01-01

    Sodium dodecyl sulphate (SDS), an anionic surfactant, has been used extensively due to its low cost and excellent foaming properties. Fifteen different bacterial isolates capable of degrading SDS were isolated from detergent contaminated soil by enrichment culture technique and the degradation efficiency was assessed by Methylene Blue Active Substances (MBAS) assay. The most efficient SDS degrading isolate was selected and identified as Pseudomonas aeruginosa S7. The selected isolate was found to harbor a single 6-kb plasmid. Acridine orange, ethidium bromide, SDS and elevated temperatures of incubation failed to cure the plasmid. The cured derivatives of SDS degrading Pseudomonas aeruginosa were obtained only when ethidium bromide and elevated temperature (40 °C) were used together. Transformation of E. coli DH5α with plasmid isolated from S7 resulted in subsequent growth of the transformants on minimal salt media with SDS (0.1%) as the sole source of carbon. The SDS degradation ability of S7 and the transformant was found to be similar as assessed by Methylene Blue Active Substance Assay. The antibiotic resistance profiles of S7, competent DH5α and transformant were analyzed and it was noted that the transfer of antibiotic resistance correlated with the transfer of plasmid as well as SDS degrading property.

  7. Crystal structure of Mox-1, a unique plasmid-mediated class C β-lactamase with hydrolytic activity towards moxalactam.

    Science.gov (United States)

    Oguri, Takuma; Furuyama, Takamitsu; Okuno, Takashi; Ishii, Yoshikazu; Tateda, Kazuhiro; Bonomo, Robert A; Shimizu-Ibuka, Akiko

    2014-07-01

    Mox-1 is a unique plasmid-mediated class C β-lactamase that hydrolyzes penicillins, cephalothin, and the expanded-spectrum cephalosporins cefepime and moxalactam. In order to understand the unique substrate profile of this enzyme, we determined the X-ray crystallographic structure of Mox-1 β-lactamase at a 1.5-Å resolution. The overall structure of Mox-1 β-lactamase resembles that of other AmpC enzymes, with some notable exceptions. First, comparison with other enzymes whose structures have been solved reveals significant differences in the composition of amino acids that make up the hydrogen-bonding network and the position of structural elements in the substrate-binding cavity. Second, the main-chain electron density is not observed in two regions, one containing amino acid residues 214 to 216 positioned in the Ω loop and the other in the N terminus of the B3 β-strand corresponding to amino acid residues 303 to 306. The last two observations suggest that there is significant structural flexibility of these regions, a property which may impact the recognition and binding of substrates in Mox-1. These important differences allow us to propose that the binding of moxalactam in Mox-1 is facilitated by the avoidance of steric clashes, indicating that a substrate-induced conformational change underlies the basis of the hydrolytic profile of Mox-1 β-lactamase.

  8. Complex integrons containing qnrB4-ampC (bla(DHA-1)) in plasmids of multidrug-resistant Citrobacter freundii from wastewater.

    Science.gov (United States)

    Yim, Grace; Kwong, Waldan; Davies, Julian; Miao, Vivian

    2013-02-01

    Microbial populations in wastewater treatment plants (WWTPs) are increasingly being recognized as environmental reservoirs of antibiotic resistance genes. PCR amplicons for plasmid-mediated quinolone resistance determinants qnrA, qnrB, and qnrS were recorded in samples from a WWTP in Vancouver, British Columbia. Six strains of ciprofloxacin-resistant Citrobacter freundii were isolated and found to carry mutations in gyrA and parC, as well as multiple plasmid-borne resistance genes, collectively including qnrB; aac(6')-Ib-cr; β-lactamase-encoding genes from molecular classes A (blaTEM-1), C (ampC), D (blaOXA-1, blaOXA-10); and genes for resistance to 5 other types of antibiotics. In 3 strains, large (>60 kb) plasmids carried qnrB4 and ampC as part of a complex integron in a 14 kb arrangement that has been reported worldwide but, until recently, only among pathogenic strains of Klebsiella. Analysis of single-nucleotide polymorphisms in the qnrB4-ampC regions infers 2 introductions into the WWTP environment. These results suggest recent passage of plasmid-borne fluoroquinolone and β-lactam resistance genes from pathogens to bacteria that may be indigenous inhabitants of WWTPs, thus contributing to an environmental pool of antibiotic resistance.

  9. Plasmid-Mediated Dimethoate Degradation by Bacillus licheniformis Isolated From a Fresh Water Fish Labeo rohita

    Directory of Open Access Journals (Sweden)

    Manisha Deb Mandal

    2005-01-01

    Full Text Available The Bacillus licheniformis strain isolated from the intestine of Labeo rohita by an enrichment technique showed capability of utilizing dimethoate as the sole source of carbon. The bacterium rapidly utilized dimethoate beyond 0.6 mg/mL and showed prolific growth in a mineral salts medium containing 0.45 mg/mL dimethoate. The isolated B licheniformis exhibited high level of tolerance of dimethoate (3.5 mg/mL in nutrient broth, while its cured mutant did not tolerate dimethoate beyond 0.45 mg/mL and it was unable to utilize dimethoate. The wild B licheniformis strain transferred dimethoate degradation property to E coli C600 (Nar, F− strain. The transconjugant harbored a plasmid of the same molecular size (approximately 54 kb as that of the donor plasmid; the cured strain was plasmid less. Thus a single plasmid of approximately 54 kb was involved in dimethoate degradation. Genes encoding resistance to antibiotic and heavy metal were also located on the plasmid.

  10. Plasmid-Mediated Dimethoate Degradation by Bacillus licheniformis Isolated From a Fresh Water Fish Labeo rohita

    Science.gov (United States)

    2005-01-01

    The Bacillus licheniformis strain isolated from the intestine of Labeo rohita by an enrichment technique showed capability of utilizing dimethoate as the sole source of carbon. The bacterium rapidly utilized dimethoate beyond 0.6 mg/mL and showed prolific growth in a mineral salts medium containing 0.45 mg/mL dimethoate. The isolated B licheniformis exhibited high level of tolerance of dimethoate (3.5 mg/mL) in nutrient broth, while its cured mutant did not tolerate dimethoate beyond 0.45 mg/mL and it was unable to utilize dimethoate. The wild B licheniformis strain transferred dimethoate degradation property to E coli C600 (Nar, F−) strain. The transconjugant harbored a plasmid of the same molecular size (approximately 54 kb) as that of the donor plasmid; the cured strain was plasmid less. Thus a single plasmid of approximately 54 kb was involved in dimethoate degradation. Genes encoding resistance to antibiotic and heavy metal were also located on the plasmid. PMID:16192686

  11. 伤寒杆菌耐喹诺酮类机制分子生物学基础研究%A study on the molecular basis of quinolone resistance mechanism in salmonella typhi

    Institute of Scientific and Technical Information of China (English)

    肖永红; 王其南

    2000-01-01

    Objective To study the relationship between the gene mutations of DNA gyrase subunit A(gyrA)and quinolone resistance in Salmonella typhi. Methods The genes of gyrA DNA of Salmonella typhi S275(a clinically isolated quinolone susceptible strain)and its spontaneous quinolone-re-sistant mutant RGl were examined in this study with polymerase chain reaction(PCR),restrictive frag-ments length polymorphism(RFLP),single strand conformational polymorphism(SSCP)and nucleotide sequencing. Results Nudeotide sequencing of gyrA in Salmonella typhi S275 revealed that the bases of 128~426 kept highly conservative as compared with those of Escherichia coli KL-16,with only 7.49%difference in the gyrA nucleotides 128~426 between the two strains.Most of the mutations were silent mutations,which contributed to 3 amino acid substitutions in gyrase(including Thr-45→His,Arg-49→Leu and Val-56→Gly),and all these substitutions were located outside the quinolone resistance determining re-gion(amino acids 67-106 of subunit A of gyrase).In comparison with Salmonella typhi S275,a single mutation was found at base 247 of gyrA of Salmonella typhi RG1,with change transferred from T to G and led to a substitution of Ser-83→Ala.The mutation might be responsible for the increase of MICs of nalidixic acid,ofloxacin and ciprofloxacin against Salmonella typhi from 2,0.06 and<0.03 to 512,2,and 1 mg/L respectively.Ser-83→A1a was also a newly discovered substitution in gyrA of Salmonella spp.The results of PCR-RFLP and SSCP were in concordance with results of nucleotide sequencing. Conclu.sions The mutation of gyrase at the 83rd amino acid maybe play a principal role in the resistance of Salmonella typhi to quinolone.%目的 研究伤寒杆菌DNA旋转酶A亚单位基因(gyrA)变异与其耐喹诺酮类的关系.方法 应用聚合酶链反应(PCR)检测、限制性片段长度多态性(RFLP)、单链构象多态性分析(SSCP)及序列测定,对伤寒杆菌$275(临床分离敏感菌株)及

  12. Characterization of ESBL- and AmpC-Producing and Fluoroquinolone-Resistant Enterobacteriaceae Isolated from Mouflons (Ovis orientalis musimon in Austria and Germany.

    Directory of Open Access Journals (Sweden)

    Igor Loncaric

    Full Text Available The aim of this study was to investigate the presence of β-lactamase producing or fluoroquinolone-resistant members of the family Enterobacteriaceae in European mouflons (Ovis orientalis musimon. The mouflon samples originated from nasal and perineal swabs and/or organ samples in cases of a suspected infection. Only one of the 32 mouflons was tested positive for the presence of Enterobacteriaceae that displayed either an ESBL/AmpC phenotype or were resistant to ciprofloxacin. The positively tested swab originated from a sample of the jejunal mucosa of a four-year old female mouflon. Two different colony morphotypes were identified as Escherichia coli and Klebsiella pneumoniae. These isolates were phenotypically and genotypically characterized in detail by a polyphasic approach. Both isolates were multi-drug resistant. The E. coli isolate belonged to the phylogenetic group B1 and sequence type (ST 744 and harboured the β-lactamase genes blaCTX-M-15 and blaOXA-1. The K. pneumoniae, identified as ST11, harboured the β-lactamase genes blaSHV-11, blaOXA-1, and blaDHA-1 as well as the plasmid-mediated quinolone resistance (PMQR gene qnrB55. The present study demonstrates that wild animals can acquire human-derived resistance determinants and such findings may indicate environmental pollution with resistance determinants from other sources.

  13. Detection and occurrence of plasmid-mediated AmpC in highly resistant gram-negative Rods

    NARCIS (Netherlands)

    E.A. Reuland (E. Ascelijn); J.P. Hays (John); D.M.C. de Jongh (Denise); E. Abdelrehim (Eman); I. Willemsen (Ina); J.A.J.W. Kluytmans (Jan); P.H.M. Savelkoul (Paul); C.M.J.E. Vandenbroucke-Grauls (Christina); N.A. Naiemi (Nashwan Al)

    2014-01-01

    textabstractObjectives: The aim of this study was to compare the current screening methods and to evaluate confirmation tests for phenotypic plasmidal AmpC (pAmpC) detection. Methods: For this evaluation we used 503 Enterobacteriaceae from 18 Dutch hospitals and 21 isolates previously confirmed to b

  14. Genetic organization of plasmid-mediated Qnr determinants in cefotaxime-resistant Enterobacter cloacae isolates in Korea.

    Science.gov (United States)

    Kim, Yang Soo; Kim, Eun Sil; Jeong, Jin-Yong

    2010-11-01

    Because of the strong association between qnr genes and plasmids carrying β-lactamase genes, we screened 176 clinical isolates of Enterobacter cloacae with cefotaxime MICs of ≥16 μg/mL for qnr genes. The qnrA, qnrB, and qnrS genes were detected in 18 (10.2%), 11 (6.2%), and 1 (0.56%) of the isolates, respectively. The genetic environments of the plasmids encoding these qnr genes were analyzed.

  15. Antimicrobial resistance in commensal Escherichia coli isolated from animals at slaughter

    Science.gov (United States)

    Wasyl, Dariusz; Hoszowski, Andrzej; Zając, Magdalena; Szulowski, Krzysztof

    2013-01-01

    Monitoring of antimicrobial resistance in commensal Escherichia coli (N = 3430) isolated from slaughtered broilers, laying hens, turkeys, swine, and cattle in Poland has been run between 2009 and 2012. Based on minimal inhibitory concentration (MIC) microbiological resistance to each of 14 tested antimicrobials was found reaching the highest values for tetracycline (43.3%), ampicillin (42.3%), and ciprofloxacin (39.0%) whereas the lowest for colistin (0.9%), cephalosporins (3.6 ÷ 3.8%), and florfenicol (3.8%). The highest prevalence of resistance was noted in broiler and turkey isolates, whereas it was rare in cattle. That finding along with resistance patterns specific to isolation source might reflect antimicrobial consumption, usage preferences or management practices in specific animals. Regression analysis has identified changes in prevalence of microbiological resistance and shifts of MIC values. Critically important fluoroquinolone resistance was worrisome in poultry isolates, but did not change over the study period. The difference (4.7%) between resistance to ciprofloxacin and nalidixic acid indicated the scale of plasmid-mediated quinolone resistance. Cephalosporin resistance were found in less than 3.8% of the isolates but an increasing trends were observed in poultry and MIC shift in the ones from cattle. Gentamycin resistance was also increasing in E. coli of turkey and cattle origin although prevalence of streptomycin resistance in laying hens decreased considerably. Simultaneously, decreasing MIC for phenicols observed in cattle and layers isolates as well as tetracycline values in E. coli from laying hens prove that antimicrobial resistance is multivariable phenomenon not only directly related to antimicrobial usage. Further studies should elucidate the scope of commensal E. coli as reservoirs of resistance genes, their spread and possible threats for human and animal health. PMID:23935596

  16. Chemical structure and pharmacokinetics of novel quinolone agents represented by avarofloxacin, delafloxacin, finafloxacin, zabofloxacin and nemonoxacin.

    Science.gov (United States)

    Kocsis, Bela; Domokos, J; Szabo, D

    2016-05-23

    Quinolones are potent antimicrobial agents with a basic chemical structure of bicyclic ring. Fluorine atom at position C-6 and various substitutions on the basic quinolone structure yielded fluoroquinolones, namely norfloxacin, ciprofloxacin, levofloxacin, moxifloxacin and numerous other agents. The target molecules of quinolones and fluoroquinolones are bacterial gyrase and topoisomerase IV enzymes. Broad-spectrum and excellent tissue penetration make fluoroquinolones potent agents but their toxic side effects and increasing number of resistant pathogens set limits on their use. This review focuses on recent advances concerning quinolones and fluoroquinolones, we will be summarising chemical structure, mode of action, pharmacokinetic properties and toxicity. We will be describing fluoroquinolones introduced in clinical trials, namely avarofloxacin, delafloxacin, finafloxacin, zabofloxacin and non-fluorinated nemonoxacin. These agents have been proved to have enhanced antibacterial effect even against ciprofloxacin resistant pathogens, and found to be well tolerated in both oral and parenteral administrations. These features are going to make them potential antimicrobial agents in the future.

  17. IncHI2 Plasmids Are Predominant in Antibiotic-Resistant Salmonella Isolates

    Science.gov (United States)

    Chen, Wenyao; Fang, Tingzi; Zhou, Xiujuan; Zhang, Daofeng; Shi, Xianming; Shi, Chunlei

    2016-01-01

    The wide usage of antibiotics contributes to the increase in the prevalence of antibiotic-resistant Salmonella. Plasmids play a critical role in horizontal transfer of antibiotic resistance markers in Salmonella. This study aimed to screen and characterize plasmid profiles responsible for antibiotic resistance in Salmonella and ultimately to clarify the molecular mechanism of transferable plasmid-mediated antibiotic resistance. A total of 226 Salmonella isolates were examined for antimicrobial susceptibility by a disk diffusion method. Thirty-two isolates (14.2%) were resistant to at least one antibiotic. The presence of plasmid-mediated quinolone resistance (PMQR) genes and β-lactamase genes were established by PCR amplification. PCR-based replicon typing revealed that these 32 isolates represented seven plasmid incompatibility groups (IncP, HI2, A/C, FIIs, FIA, FIB, and I1), and the IncHI2 (59.4%) was predominant. Antibiotic resistance markers located on plasmids were identified through plasmid curing. Fifteen phenotypic variants were obtained with the curing efficiency of 46.9% (15/32). The cured plasmids mainly belong to the HI2 incompatibility group. The elimination of IncHI2 plasmids correlated with the loss of β-lactamase genes (blaOXA-1 and blaTEM-1) and PMQR genes (qnrA and aac(6′)-Ib-cr). Both IncHI2 and IncI1 plasmids in a S. enterica serovar Indiana isolate SJTUF 10584 were lost by curing. The blaCMY -2-carrying plasmid pS10584 from SJTUF 10584 was fully sequenced. Sequence analysis revealed that it possessed a plasmid scaffold typical for IncI1 plasmids with the unique genetic arrangement of IS1294-ΔISEcp1-blaCMY -2-blc-sugE-ΔecnR inserted into the colicin gene cia. These data suggested that IncHI2 was the major plasmid lineage contributing to the dissemination of antibiotic resistance in Salmonella and the activity of multiple mobile genetic elements may contribute to antibiotic resistance evolution and dissemination between different plasmid

  18. The Magnitude of the Association between Fluoroquinolone Use and Quinolone-Resistant Escherichia coli and Klebsiella pneumoniae May Be Lower than Previously Reported

    OpenAIRE

    Bolon, Maureen K.; Wright, Sharon B.; Gold, Howard S.; Carmeli, Yehuda

    2004-01-01

    Case-control analyses of resistant versus susceptible isolates have implicated fluoroquinolone exposure as a strong risk factor for fluoroquinolone-resistant isolates of Enterobacteriaceae. We suspect that such methodology may overestimate this association. A total of 84 cases with fluoroquinolone-resistant isolates and 578 cases with fluoroquinolone-susceptible isolates of Escherichia coli or Klebsiella pneumoniae were compared with 608 hospitalized controls in parallel multivariable analyse...

  19. Phenotypic and Molecular Characterization of Plasmid Mediated AmpC β-Lactamases among Escherichia coli, Klebsiella spp., and Proteus mirabilis Isolated from Urinary Tract Infections in Egyptian Hospitals

    Directory of Open Access Journals (Sweden)

    Mai M. Helmy

    2014-01-01

    Full Text Available The incidence of resistance by Enterobacteriaceae to β-lactam/β-lactamase inhibitors combination is increasing in Egypt. Three phenotypic techniques, comprising AmpC disk diffusion and inhibition dependent methods using phenylboronic acid (PBA and cloxacillin, were compared to PCR based method for detection of plasmid mediated AmpC β-lactamase in common urinary tract isolates. A total of 143 isolates, including E. coli, Klebsiella pneumonia, and Proteus mirabilis, were collected from urinary tract infections cases in Egyptian hospitals. Plasmid encoded AmpC genes were detected by PCR in 88.46% of cefoxitin resistant isolates. The most prevalent AmpC gene family was CIT including CMY-2, CMY-4, and two CMY-2 variants. The second prevalent gene was DHA-1 which was detected in E. coli and Klebsiella pneumonia. The genes EBC, FOX, and MOX were also detected but in small percentage. Some isolates were identified as having more than one pAmpC gene. The overall sensitivity and specificity of phenotypic tests for detection of AmpC β-lactamase showed that AmpC disk diffusion and inhibition dependent method by cloxacillin were the most sensitive and the most specific disk tests. PCR remains the gold standard for detection of AmpC β-lactamases. This study represents the first report of CMY-2 variants of CMY-42 and CMY-102 β-lactamase-producing E. coli, Klebsiella pneumonia, and Proteus mirabilis isolates in Egypt.

  20. Improving quinolone use in hospitals by using a bundle of interventions in an interrupted time series analysis.

    Science.gov (United States)

    Willemsen, Ina; Cooper, Ben; van Buitenen, Carin; Winters, Marjolein; Andriesse, Gunnar; Kluytmans, Jan

    2010-09-01

    The objectives of the present study were to determine the effects of multiple targeted interventions on the level of use of quinolones and the observed rates of resistance to quinolones in Escherichia coli isolates from hospitalized patients. A bundle consisting of four interventions to improve the use of quinolones was implemented. The outcome was measured from the monthly levels of use of intravenous (i.v.) and oral quinolones and the susceptibility patterns for E. coli isolates from hospitalized patients. Statistical analyses were performed using segmented regression analysis and segmented Poisson regression models. Before the bundle was implemented, the annual use of quinolones was 2.7 defined daily doses (DDDs)/100 patient days. After the interventions, in 2007, this was reduced to 1.7 DDDs/100 patient days. The first intervention, a switch from i.v. to oral medication, was associated with a stepwise reduction in i.v. quinolone use of 71 prescribed daily doses (PDDs) per month (95% confidence interval [CI] = 47 to 95 PDDs/month, P quinolones (reduction, 107 PDDs/month [95% CI = 58 to 156 PDDs/month). Before the interventions the quinolone resistance rate was increasing, on average, by 4.6% (95% CI = 2.6 to 6.1%) per year. This increase leveled off, which was associated with intervention 2 and intervention 4, active monitoring of prescriptions and feedback. Trends in resistance to other antimicrobial agents did not change. This study showed that the hospital-wide use of quinolones can be significantly reduced by an active policy consisting of multiple interventions. There was also a stepwise reduction in the rate of quinolone resistance associated with the bundle of interventions.

  1. The inactivation of RNase G reduces the Stenotrophomonas maltophilia susceptibility to quinolones by triggering the heat shock response.

    Directory of Open Access Journals (Sweden)

    Alejandra eBernardini

    2015-10-01

    Full Text Available Quinolone resistance is usually due to mutations in the genes encoding bacterial topoisomerases. However different reports have shown that neither clinical quinolone resistant isolates nor in vitro obtained S. maltophilia mutants present mutations in such genes. The mechanisms so far described consist on efflux pumps' overexpression. Our objective is to get information on novel mechanisms of S. maltophilia quinolone resistance. For this purpose, a transposon-insertion mutant library was obtained in S. maltophilia D457.. One mutant presenting reduced susceptibility to nalidixic acid was selected. Inverse PCR showed that the inactivated gene encodes RNase G. Complementation of the mutant with wild-type RNase G allele restored the susceptibility to quinolones. Transcriptomic and real-time RT-PCR analyses showed that several genes encoding heat-shock response proteins were expressed at higher levels in the RNase defective mutant than in the wild-type strain. In agreement with this situation, heat-shock reduces the S. maltophilia susceptibility to quinolone. We can then conclude that the inactivation of the RNase G reduces the susceptibility of S. maltophilia to quinolones, most likely by regulating the expression of heat-shock response genes. Heat-shock induces a transient phenotype of quinolone resistance in S. maltophilia.

  2. Antibiotic resistance genes occurrence and bacterial community composition in the Liuxi River

    Directory of Open Access Journals (Sweden)

    Wenguang eXiong

    2014-12-01

    Full Text Available Antibiotic resistance genes (ARGs in the environment have paid great concern due to their health risk. We investigated antibiotics concentrations (tetracyclines, sulfonamides and fluoroquinolones, ARGs abundances (tetracycline, sulfonamide and plasmid-mediated quinolone resistance (PMQR genes, and bacterial community composition in sediment and water samples in the Liuxi River, China. Antibiotics concentrations were determined by ultra-performance liquid chromatography-electrospray tandem mass spectrometry. ARGs abundances were quantified by a culture-independent method. Bacterial community composition was analyzed by metagenomic approach based on Ion Torrent Personal Genome Machine platform. Antibiotics concentrations were at the levels of 1.19 to 622 ug kg-1 in sediment samples and below the limit of detection to 127 ng L-1 in water samples. Relative abundances (ARGs copies/16S rRNA gene copies of detected ARGs were at the range of 10-5 to 10-2. The dominant phyla were Proteobacteria, Bacteroidetes and Verrucomicrobia in sediment samples, and were Proteobacteria, Actinobacteria and Bacteroidetes in water samples. The results indicated that the river environment was contaminated by antibiotics and may be as a reservoir of ARGs. This study provided quantitative data on antibiotics, ARGs and bacterial community composition in the Liuxi River, a geographical location different from the reported studies.

  3. Countrywide dissemination of a DHA-1-type plasmid-mediated AmpC β-lactamase-producing Klebsiella pneumoniae ST11 international high-risk clone in Hungary, 2009-2013.

    Science.gov (United States)

    Kis, Zoltán; Tóth, Ákos; Jánvári, Laura; Damjanova, Ivelina

    2016-09-01

    The first plasmid-mediated AmpC β-lactamase-producing Klebsiella pneumoniae (pAmpC KP) isolate was detected in December 2009 in Hungary. Hungarian microbiological laboratories were asked to send all KP strains showing cefoxitin resistance and decreased susceptibility or resistance to any third-generation cephalosporins to the Reference Laboratories at the National Center for Epidemiology. Investigation was conducted in order to outline spatio-temporal distribution and genetic characterization of pAmpC-KP isolates in Hungary. Between December 2009 and December 2013, 312 consecutive KP clinical isolates were confirmed as producing pAmpCs. All isolates showed resistance to third-generation cephalosporins, aminoglycosides and fluoroquinolones, and 77 % were non-susceptible to at least one carbapenem. Analysis of β-lactamase genes showed blaDHA-1 in all and additionally blaCTX-M-15 in 90 % of isolates. PFGE typing revealed 12 pulsotypes; of these, KP053 (262/312) and KP070 (38/312) belonged to sequence type ST11 and comprised 96 % of the isolates. The blaDHA-1 and blaCTX-M-15 co-producing KP053/ST11 clone affected 234 patients and spread to 55 healthcare centres across Hungary during the study period. Three KP053 isolates were also resistant to colistin. In two of these, the mgrB gene was truncated by IS10R, while in the third isolate, insertional inactivation of mgrB by ISKPn14 was identified. Hungary is the first European country showing endemic spread of blaDHA-1 facilitated by the international high-risk clone ST11. The rapid countrywide spread of this multidrug-resistant clone seriously endangers Hungarian healthcare facilities and warrants strengthening of infection control practices and prudent use of carbapenems and colistin.

  4. Molecular characterization of extended-spectrum β-lactamase, plasmid-mediated AmpC cephalosporinase and carbapenemase genes among Enterobacteriaceae isolates in five medical centres of East and West Azerbaijan, Iran.

    Science.gov (United States)

    Sadeghi, Mohammad Reza; Ghotaslou, Reza; Akhi, Mohammad Taghi; Asgharzadeh, Mohammad; Hasani, Alka

    2016-11-01

    Very little is known about the occurrence and various types of extended-spectrum β-lactamase (ESBL), AmpC and carbapenemase in Iran. The aims of this study were to determine the prevalence of ESBLs, AmpCs and carbapenemase genes among Enterobacteriaceae in Azerbaijan and to characterize the genetic composition of the detected genes. A total of 307 Enterobacteriaceae isolates, recovered from five medical centres, were screened for ESBL, AmpC and carbapenemase activities by the disc diffusion method and phenotypic confirmatory tests. The 162 selected strains (third-generation cephalosporins, cefoxitin- or carbapenem-resistant strains with positive or negative phenotypic confirmatory tests) were selected for multiplex PCR screening for β-lactamase genes, and detected genes were confirmed by sequencing. Of 162 isolates, 156 harboured 1 to 6 β-lactamase genes of 41 types. The most prevalent genes were blaTEM-1 (29.9 %), followed by blaCTX-M-15 (25.7 %). Plasmid-mediated AmpC was detected in 66 strains (21.5 %) alone or in combination with other genes. Carbapenemase-encoding genes were detected in 18 strains (5.8 %) of 27 carbapenem-non-susceptible isolates including 11, 7, 3 and 1 cases of blaOXA-48, blaNDM-1, blaKPC-2 and blaKPC-3 genes, respectively. Interestingly, 148 (94.8 %) of 156 strains with any β-lactamase gene were found to have a multidrug-resistant pattern. The rate of resistance to β-lactams and multidrug-resistant Enterobacteriaceae is high in Azerbaijan. All positive strains for carbapenemase genes were resistant to all β-lactams. The present study reveals the high occurrence of CTX-M-type ESBLs followed by TEM and SHV variants among Enterobacteriaceae isolates. East Azerbaijan seems to be an alarming focus for OXA-48, NDM-1 and KPC dissemination.

  5. Molecular characterization of multidrug-resistant Shigella spp. of food origin.

    Science.gov (United States)

    Ahmed, Ashraf M; Shimamoto, Tadashi

    2015-02-02

    Shigella spp. are the causative agents of food-borne shigellosis, an acute enteric infection. The emergence of multidrug-resistant clinical isolates of Shigella presents an increasing challenge for clinicians in the treatment of shigellosis. Several studies worldwide have characterized the molecular basis of antibiotic resistance in clinical Shigella isolates of human origin, however, to date, no such characterization has been reported for Shigella spp. of food origin. In this study, we characterized the genetic basis of multidrug resistance in Shigella spp. isolated from 1600 food samples (800 meat products and 800 dairy products) collected from different street venders, butchers, retail markets, and slaughterhouses in Egypt. Twenty-four out of 27 Shigella isolates (88.9%) showed multidrug resistance phenotypes to at least three classes of antimicrobials. The multidrug-resistant Shigella spp. were as follows: Shigella flexneri (66.7%), Shigella sonnei (18.5%), and Shigella dysenteriae (3.7%). The highest resistance was to streptomycin (100.0%), then to kanamycin (95.8%), nalidixic acid (95.8%), tetracycline (95.8%), spectinomycin (93.6%), ampicillin (87.5%), and sulfamethoxazole/trimethoprim (87.5%). PCR and DNA sequencing were used to screen and characterize integrons and antibiotic resistance genes. Our results indicated that 11.1% and 74.1% of isolates were positive for class 1 and class 2 integrons, respectively. Beta-lactamase-encoding genes were identified in 77.8% of isolates, and plasmid-mediated quinolone resistance genes were identified in 44.4% of isolates. These data provide useful information to better understand the molecular basis of antimicrobial resistance in Shigella spp. To the best of our knowledge, this is the first report of the molecular characterization of antibiotic resistance in Shigella spp. isolated from food.

  6. Emergence of CTX-M-3, TEM-1 and a new plasmid-mediated MOX-4 AmpC in a multiresistant Aeromonas caviae isolate from a patient with pneumonia.

    Science.gov (United States)

    Ye, Ying; Xu, Xi-Hai; Li, Jia-Bin

    2010-07-01

    Aeromonas species rarely cause pulmonary infection. We report, for what is believed to be the first time, a case of severe pneumonia in a cancer patient caused by Aeromonas caviae. Detailed microbiological investigation revealed that this isolate carried three beta-lactamase-encoding genes (encoding MOX-4, CTX-M-3 and TEM-1) conferring resistance to all beta-lactams but imipenem. The beta-lactamase with a pI of 9.0 was transferred by conjugation and associated with a 7.3 kb plasmid, as demonstrated by Southern blot hybridization. Analysis of the nucleotide and amino acid sequences showed a new ampC gene that was closely related to those encoding the MOX-1, MOX-2 and MOX-3 beta-lactamases. This new plasmid-mediated AmpC beta-lactamase from China was named MOX-4. This is believed to be the first report of MOX-4, CTX-M-3 and TEM-1 beta-lactamases in a multiresistant A. caviae.

  7. In vitro activities and detection performances of cefmetazole and flomoxef for extended-spectrum β-lactamase and plasmid-mediated AmpC β-lactamase-producing Enterobacteriaceae.

    Science.gov (United States)

    Matsumura, Yasufumi; Yamamoto, Masaki; Nagao, Miki; Tanaka, Michio; Takakura, Shunji; Ichiyama, Satoshi

    2016-04-01

    To investigate the in vitro activities of cephamycins (cefmetazole and flomoxef) for extended-spectrum β-lactamase (ESBL)- and plasmid-mediated AmpC β-lactamase (pAmpC)-producing Enterobacteriaceae, a total of 574 third-generation cephalosporin-resistant clinical isolates were collected at a Japanese multicenter study. PCR and sequencing identified 394 isolates with only ESBL genes, 63 isolates with only pAmpC genes, and 6 isolates with both ESBL and pAmpC genes. blaCTX-M types predominated 95.5% of the ESBL genes, and blaCMY-2 predominated 91.3% of the pAmpC genes. The MIC50/90 values of cefmetazole and flomoxef were ≤ 1/4 and ≤ 1/≤ 1 μg/mL for isolates with only ESBL genes, respectively, and 16/>16 and 8/16 μg/mL for isolates with only pAmpC genes, respectively. Flomoxef ≥ 4 μg/mL had the best screening performance for the detection of isolates with pAmpC genes. Flomoxef had better in vitro activities against ESBL-producing Enterobacteriaceae and provided a clearer distinction between ESBL and pAmpC-producing Enterobacteriaceae compared to cefmetazole.

  8. Cefotaxime for the detection of extended-spectrum β-lactamase or plasmid-mediated AmpC β-lactamase and clinical characteristics of cefotaxime-non-susceptible Escherichia coli and Klebsiella pneumoniae bacteraemia.

    Science.gov (United States)

    Matsumura, Y; Yamamoto, M; Matsushima, A; Nagao, M; Ito, Y; Takakura, S; Ichiyama, S

    2012-08-01

    We investigated the performance of cefotaxime for the detection of extended-spectrum β-lactamase (ESBL) or plasmid-mediated AmpC β-lactamase (pAmpC) and the clinical characteristics of cefotaxime-non-susceptible Escherichia coli or Klebsiella pneumoniae (CTXNS-EK) bacteraemia. All of the consecutive bloodstream isolates between 2005 and 2010 in a Japanese university hospital were characterised using polymerase chain reaction (PCR). Risk factors and outcomes of CTXNS-EK were analysed by multivariate logistic regression analysis. We identified 58 CTXNS-EK (15.6%) from 249 E. coli and 122 K. pneumoniae. Cefotaxime with a minimum inhibitory concentration (MIC) of >1 μg/mL had a sensitivity of 98.3% and a specificity of 99.7% for the detection of ESBL or pAmpC. CTXNS-EK had increased from 4.5% in 2005 to 23% in 2009. Risk factors for CTXNS-EK were previous isolation of multidrug-resistant bacteria, use of oxyimino-cephalosporins or fluoroquinolones, and high Sequential Organ Failure Assessment (SOFA) score. Patients with CTXNS-EK bacteraemia less frequently received appropriate empirical therapy than patients with cefotaxime-susceptible EK bacteraemia (81% vs. 97%, pcefotaxime alone can identify ESBL or pAmpC producers. CTXNS-EK is an important and increasingly prevalent bacteraemia pathogen.

  9. Molecular characterization of multidrug-resistant Klebsiella pneumoniae isolates.

    Science.gov (United States)

    Hou, Xiang-hua; Song, Xiu-yu; Ma, Xiao-bo; Zhang, Shi-yang; Zhang, Jia-qin

    2015-01-01

    Klebsiella pneumoniae is an important cause of healthcare-associated infections worldwide. Selective pressure, the extensive use of antibiotics, and the conjugational transmission of antibiotic resistance genes across bacterial species and genera facilitate the emergence of multidrug-resistant (MDR) K. pneumoniae. Here, we examined the occurrence, phenotypes and genetic features of MDR K. pneumoniae isolated from patients in intensive care units (ICUs) at the First Affiliated Hospital of Xiamen University in Xiamen, China, from January to December 2011. Thirty-eight MDR K. pneumoniae strains were collected. These MDR K. pneumoniae isolates possessed at least seven antibiotic resistance determinants, which contribute to the high-level resistance of these bacteria to aminoglycosides, macrolides, quinolones and β-lactams. Among these isolates, 24 strains were extended-spectrum β-lactamase (ESBL) producers, 2 strains were AmpC producers, and 12 strains were both ESBL and AmpC producers. The 38 MDR isolates also contained class I (28/38) and class II integrons (10/38). All 28 class I-positive isolates contained aacC1, aacC4, orfX, orfX' and aadA1 genes. β-lactam resistance was conferred through bla SHV (22/38), bla TEM (10/38), and bla CTX-M (7/38). The highly conserved bla KPC-2 (37/38) and bla OXA-23(1/38) alleles were responsible for carbapenem resistance, and a gyrAsite mutation (27/38) and the plasmid-mediated qnrB gene (13/38) were responsible for quinolone resistance. Repetitive-sequence-based PCR (REP-PCR) fingerprinting of these MDR strains revealed the presence of five groups and sixteen patterns. The MDR strains from unrelated groups showed different drug resistance patterns; however, some homologous strains also showed different drug resistance profiles. Therefore, REP-PCR-based analyses can provide information to evaluate the epidemic status of nosocomial infection caused by MDR K. pneumoniae; however, this test lacks the power to discriminate some

  10. Molecular characterization of multidrug-resistant Klebsiella pneumoniae isolates

    Directory of Open Access Journals (Sweden)

    Xiang-hua Hou

    2015-09-01

    Full Text Available Klebsiella pneumoniae is an important cause of healthcare-associated infections worldwide. Selective pressure, the extensive use of antibiotics, and the conjugational transmission of antibiotic resistance genes across bacterial species and genera facilitate the emergence of multidrug-resistant (MDR K. pneumoniae. Here, we examined the occurrence, phenotypes and genetic features of MDR K. pneumoniae isolated from patients in intensive care units (ICUs at the First Affiliated Hospital of Xiamen University in Xiamen, China, from January to December 2011. Thirty-eight MDR K. pneumoniae strains were collected. These MDR K. pneumoniae isolates possessed at least seven antibiotic resistance determinants, which contribute to the high-level resistance of these bacteria to aminoglycosides, macrolides, quinolones and β-lactams. Among these isolates, 24 strains were extended-spectrum β-lactamase (ESBL producers, 2 strains were AmpC producers, and 12 strains were both ESBL and AmpC producers. The 38 MDR isolates also contained class I (28/38 and class II integrons (10/38. All 28 class I-positive isolates contained aacC1, aacC4, orfX, orfX’ and aadA1 genes. β-lactam resistance was conferred through blaSHV (22/38, blaTEM (10/38, and blaCTX-M (7/38. The highly conserved blaKPC-2 (37/38 and blaOXA-23(1/38 alleles were responsible for carbapenem resistance, and a gyrAsite mutation (27/38 and the plasmid-mediated qnrB gene (13/38 were responsible for quinolone resistance. Repetitive-sequence-based PCR (REP-PCR fingerprinting of these MDR strains revealed the presence of five groups and sixteen patterns. The MDR strains from unrelated groups showed different drug resistance patterns; however, some homologous strains also showed different drug resistance profiles. Therefore, REP-PCR-based analyses can provide information to evaluate the epidemic status of nosocomial infection caused by MDR K. pneumoniae; however, this test lacks the power to discriminate some

  11. The effects of oral and intramuscular administration and dose escalation of enrofloxacin on the selection of quinolone resistance among Salmonella and coliforms in pigs

    DEFF Research Database (Denmark)

    Wiuff, C.; Lykkesfeldt, J.; Svendsen, O.;

    2003-01-01

    The effect of route of administration and dose of enrofloxacin (Baytril(R)) on the development of fluoroquinolone resistance in Salmonella and Escherichia coli in the intestinal tract of pigs was investigated. Healthy pigs at the age of 8-10 weeks were infected with a mixture of susceptible wild-...

  12. Comparative in vitro activities of nemonoxacin (TG-873870), a novel nonfluorinated quinolone, and other quinolones against clinical isolates.

    Science.gov (United States)

    Lauderdale, Tsai-Ling; Shiau, Yih-Ru; Lai, Jui-Fen; Chen, Hua-Chien; King, Chi-Hsin R

    2010-03-01

    The in vitro antibacterial activities of nemonoxacin (TG-873870), a novel nonfluorinated quinolone, against 770 clinical isolates were investigated. Nemonoxacin (tested as its malate salt, TG-875649) showed better in vitro activity than ciprofloxacin and levofloxacin against different species of staphylococci, streptococci, and enterococci, Neisseria gonorrhoeae, and Haemophilus influenzae. The in vitro activity of TG-875649 was also comparable to or better than that of moxifloxacin against these pathogens, which included ciprofloxacin-resistant, methicillin-resistant Staphylococcus aureus and levofloxacin-resistant Streptococcus pneumoniae.

  13. Fluoroquinolone resistance mechanisms of Shigella flexneri isolated in Bangladesh.

    Directory of Open Access Journals (Sweden)

    Ishrat J Azmi

    Full Text Available To investigate the prevalence and mechanisms of fluoroquinolone resistance in Shigella species isolated in Bangladesh and to compare with similar strains isolated in China.A total of 3789 Shigella isolates collected from Clinical Microbiology Laboratory of icddr,b, during 2004-2010 were analyzed for antibiotic susceptibility. Analysis of plasmids, plasmid-mediated quinolone-resistance genes, PFGE, and sequencing of genes of the quinolone-resistance-determining regions (QRDR were conducted in representative strains isolated in Bangladesh and compared with strains isolated in Zhengding, China. In addition, the role of efflux-pump was studied by using the efflux-pump inhibitor carbonyl cyanide-m-chlorophenylhydrazone (CCCP.Resistance to ciprofloxacin in Shigella species increased from 0% in 2004 to 44% in 2010 and S. flexneri was the predominant species. Of Shigella spp, ciprofloxacin resistant (CipR strains were mostly found among S. flexneri (8.3%, followed by S. sonnei (1.5%. Within S. flexneri (n = 2181, 14.5% were resistance to ciprofloxacin of which serotype 2a was predominant (96%. MIC of ciprofloxacin, norfloxacin, and ofloxacin were 6-32 mg/L, 8-32 mg/L, and 8-24 mg/L, respectively in S. flexneri 2a isolates. Sequencing of QRDR genes of resistant isolates showed double mutations in gyrA gene (Ser83Leu, Asp87Asn/Gly and single mutation in parC gene (Ser80Ile. A difference in amino acid substitution at position 87 was found between strains isolated in Bangladesh (Asp87Asn and China (Asp87Gly except for one. A novel mutation at position 211 (His→Tyr in gyrA gene was detected only in the Bangladeshi strains. Susceptibility to ciprofloxacin was increased by the presence of CCCP indicating the involvement of energy dependent active efflux pumps. A single PFGE type was found in isolates from Bangladesh and China suggesting their genetic relatedness.Emergence of fluoroquinolone resistance in Shigella undermines a major challenge in current

  14. Fluoroquinolone Resistance Mechanisms of Shigella flexneri Isolated in Bangladesh

    Science.gov (United States)

    Azmi, Ishrat J.; Khajanchi, Bijay K.; Akter, Fatema; Hasan, Trisheeta N.; Shahnaij, Mohammad; Akter, Mahmuda; Banik, Atanu; Sultana, Halima; Hossain, Mohammad A.; Ahmed, Mohammad K.; Faruque, Shah M.; Talukder, Kaisar A.

    2014-01-01

    Objective To investigate the prevalence and mechanisms of fluoroquinolone resistance in Shigella species isolated in Bangladesh and to compare with similar strains isolated in China. Methods A total of 3789 Shigella isolates collected from Clinical Microbiology Laboratory of icddr,b, during 2004–2010 were analyzed for antibiotic susceptibility. Analysis of plasmids, plasmid-mediated quinolone-resistance genes, PFGE, and sequencing of genes of the quinolone-resistance-determining regions (QRDR) were conducted in representative strains isolated in Bangladesh and compared with strains isolated in Zhengding, China. In addition, the role of efflux-pump was studied by using the efflux-pump inhibitor carbonyl cyanide-m-chlorophenylhydrazone (CCCP). Results Resistance to ciprofloxacin in Shigella species increased from 0% in 2004 to 44% in 2010 and S. flexneri was the predominant species. Of Shigella spp, ciprofloxacin resistant (CipR) strains were mostly found among S. flexneri (8.3%), followed by S. sonnei (1.5%). Within S. flexneri (n = 2181), 14.5% were resistance to ciprofloxacin of which serotype 2a was predominant (96%). MIC of ciprofloxacin, norfloxacin, and ofloxacin were 6–32 mg/L, 8–32 mg/L, and 8–24 mg/L, respectively in S. flexneri 2a isolates. Sequencing of QRDR genes of resistant isolates showed double mutations in gyrA gene (Ser83Leu, Asp87Asn/Gly) and single mutation in parC gene (Ser80Ile). A difference in amino acid substitution at position 87 was found between strains isolated in Bangladesh (Asp87Asn) and China (Asp87Gly) except for one. A novel mutation at position 211 (His→Tyr) in gyrA gene was detected only in the Bangladeshi strains. Susceptibility to ciprofloxacin was increased by the presence of CCCP indicating the involvement of energy dependent active efflux pumps. A single PFGE type was found in isolates from Bangladesh and China suggesting their genetic relatedness. Conclusions Emergence of fluoroquinolone resistance in Shigella

  15. Recent progress in the development of anti-malarial quinolones.

    Science.gov (United States)

    Beteck, Richard M; Smit, Frans J; Haynes, Richard K; N'Da, David D

    2014-08-30

    Available anti-malarial tools have over the ten-year period prior to 2012 dramatically reduced the number of fatalities due to malaria from one million to less than six-hundred and thirty thousand. Although fewer people now die from malaria, emerging resistance to the first-line anti-malarial drugs, namely artemisinins in combination with quinolines and arylmethanols, necessitates the urgent development of new anti-malarial drugs to curb the disease. The quinolones are a promising class of compounds, with some demonstrating potent in vitro activity against the malaria parasite. This review summarizes the progress made in the development of potential anti-malarial quinolones since 2008. The efficacy of these compounds against both asexual blood stages and other stages of the malaria parasite, the nature of putative targets, and a comparison of these properties with anti-malarial drugs currently in clinical use, are discussed.

  16. Emergence of Ciprofloxacin-Resistant Salmonella enterica Serovar Typhi in Italy.

    Science.gov (United States)

    García-Fernández, Aurora; Gallina, Silvia; Owczarek, Slawomir; Dionisi, Anna Maria; Benedetti, Ildo; Decastelli, Lucia; Luzzi, Ida

    2015-01-01

    In developed countries, typhoid fever is often associated with persons who travel to endemic areas or immigrate from them. Typhoid fever is a systemic infection caused by Salmonella enterica serovar Typhi. Because of the emergence of antimicrobial resistance to standard first-line drugs, fluoroquinolones are the drugs of choice. Resistance to ciprofloxacin by this Salmonella serovar represents an emerging public health issue. Two S. enterica ser. Typhi strains resistant to ciprofloxacin (CIP) were reported to the Italian surveillance system for foodborne and waterborne diseases (EnterNet-Italia) in 2013. The strains were isolated from two Italian tourists upon their arrival from India. A retrospective analysis of 17 other S. enterica ser. Typhi strains isolated in Italy during 2011-2013 was performed to determine their resistance to CIP. For this purpose, we assayed for susceptibility to antimicrobial agents and conducted PCR and nucleotide sequence analyses. Moreover, all strains were typed using pulsed-field gel electrophoresis to evaluate possible clonal relationships. Sixty-eight percent of the S. enterica ser. Typhi strains were resistant to CIP (MICs, 0.125-16 mg/L), and all isolates were negative for determinants of plasmid-mediated quinolone resistance. Analysis of sequences encoding DNA gyrase and topoisomerase IV subunits revealed mutations in gyrA, gyrB, and parC. Thirteen different clonal groups were detected, and the two CIP-resistant strains isolated from the individuals who visited India exhibited the same PFGE pattern. Because of these findings, the emergence of CIP-resistant S. enterica ser. Typhi isolates in Italy deserves attention, and monitoring antibiotic susceptibility is important for efficiently managing cases of typhoid fever.

  17. Synthesis of 1,2,3-Triazolo[4,5-h]quinolone Derivatives with Novel Anti-Microbial Properties against Metronidazole Resistant Helicobacter pylori.

    Science.gov (United States)

    Abu-Sini, Mohammad; Mayyas, Amal; Al-Karablieh, Nehaya; Darwish, Rula; Al-Hiari, Yusuf; Aburjai, Talal; Arabiyat, Shereen; Abu-Qatouseh, Luay

    2017-05-20

    Helicobacter pylori infection can lead to gastritis, peptic ulcer, and the development of mucosa associated lymphoid tissue (MALT) lymphoma. Treatment and eradication of H. pylori infection can prevent relapse and accelerate the healing of gastric and duodenal ulcers as well as regression of malignancy. Due to the increasing emergence of antibiotic resistance among clinical isolates of H. pylori, alternative approaches using newly discovered antimicrobial agents in combination with the standard antibiotic regimens for the treatment of H. pylori are of major importance. The purpose of the present study was to investigate the effect of newly synthesized 8-amino 7-substituted fluoroquinolone and their correspondent cyclized triazolo derivatives when either alone or combined with metronidazole against metronidazole-resistant H. pylori. Based on standard antimicrobial susceptibility testing methods and checkerboard titration assay, all of the tested compounds showed interesting antimicrobial activity against 12 clinical strains of H. pylori, with best in vitro effect for compounds 4b and 4c. Fractional inhibitory concentration (FIC) mean values showed synergistic pattern in all compounds of Group 5. In addition, additive activities of some of the tested compounds of Group 4 were observed when combined with metronidazole. In contrast, the tested compounds showed no significant urease inhibition activity. These results support the potential of new fluoroquinolone derivatives to be useful in combination with anti-H. pylori drugs in the management of H. pylori-associated diseases.

  18. Rational Design, Synthesis, and Biological Evaluation of Heterocyclic Quinolones Targeting the Respiratory Chain of Mycobacterium tuberculosis.

    Science.gov (United States)

    Hong, W David; Gibbons, Peter D; Leung, Suet C; Amewu, Richard; Stocks, Paul A; Stachulski, Andrew; Horta, Pedro; Cristiano, Maria L S; Shone, Alison E; Moss, Darren; Ardrey, Alison; Sharma, Raman; Warman, Ashley J; Bedingfield, Paul T P; Fisher, Nicholas E; Aljayyoussi, Ghaith; Mead, Sally; Caws, Maxine; Berry, Neil G; Ward, Stephen A; Biagini, Giancarlo A; O'Neill, Paul M; Nixon, Gemma L

    2017-05-11

    A high-throughput screen (HTS) was undertaken against the respiratory chain dehydrogenase component, NADH:menaquinone oxidoreductase (Ndh) of Mycobacterium tuberculosis (Mtb). The 11000 compounds were selected for the HTS based on the known phenothiazine Ndh inhibitors, trifluoperazine and thioridazine. Combined HTS (11000 compounds) and in-house screening of a limited number of quinolones (50 compounds) identified ∼100 hits and four distinct chemotypes, the most promising of which contained the quinolone core. Subsequent Mtb screening of the complete in-house quinolone library (350 compounds) identified a further ∼90 hits across three quinolone subtemplates. Quinolones containing the amine-based side chain were selected as the pharmacophore for further modification, resulting in metabolically stable quinolones effective against multi drug resistant (MDR) Mtb. The lead compound, 42a (MTC420), displays acceptable antituberculosis activity (Mtb IC50 = 525 nM, Mtb Wayne IC50 = 76 nM, and MDR Mtb patient isolates IC50 = 140 nM) and favorable pharmacokinetic and toxicological profiles.

  19. [The history of the development and changes of quinolone antibacterial agents].

    Science.gov (United States)

    Takahashi, Hisashi; Hayakawa, Isao; Akimoto, Takeshi

    2003-01-01

    The quinolones, especially the new quinolones (the 6-fluoroquinolones), are the synthetic antibacterial agents to rival the Beta-lactam and the macrolide antibacterials for impact in clinical usage in the antibacterial therapeutic field. They have a broad antibacterial spectrum of activity against Gram-positive, Gram-negative and mycobacterial pathogens as well as anaerobes. Further, they show good-to-moderate oral absorption and tissue penetration with favorable pharmacokinetics in humans resulting in high clinical efficacy in the treatment of many kinds of infections. They also exhibit excellent safety profiles as well as those of oral Beta-lactam antibiotics. The bacterial effects of quinolones inhibit the function of bacterial DNA gyrase and topoisomerase IV. The history of the development of the quinolones originated from nalidixic acid (NA), developed in 1962. In addition, the breakthrough in the drug design for the scaffold and the basic side chains have allowed improvements to be made to the first new quinolone, norfloxacin (NFLX), patented in 1978. Although currently more than 10,000 compounds have been already synthesized in the world, only two percent of them were developed and tested in clinical studies. Furthermore, out of all these compounds, only twenty have been successfully launched into the market. In this paper, the history of the development and changes of the quinolones are described from the first quinolone, NA, via, the first new quinolone (6-fluorinated quinolone) NFLX, to the latest extended-spectrum quinolone antibacterial agents against multi-drug resistant bacterial infections. NA has only modest activity against Gram-negative bacteria and low oral absorption, therefore a suitable candidate for treatment of systemic infections (UTIs) is required. Since the original discovery of NA, a series of quinolones, which are referred to as the old quinolones, have been developed leading to the first new quinolone, NFLX, with moderate improvements

  20. DRUG-INTERACTIONS WITH QUINOLONE ANTIBACTERIALS

    NARCIS (Netherlands)

    BROUWERS, JRBJ

    1992-01-01

    The quinolone antibacterials are prone to many interactions with other drugs. Quinolone absorption is markedly reduced with antacids containing aluminium, magnesium and/or calcium and therapeutic failure may result. Other metallic ion-containing drugs, such as sucralfate, iron salts, and zinc salts,

  1. DRUG-INTERACTIONS WITH QUINOLONE ANTIBACTERIALS

    NARCIS (Netherlands)

    BROUWERS, JRBJ

    1992-01-01

    The quinolone antibacterials are prone to many interactions with other drugs. Quinolone absorption is markedly reduced with antacids containing aluminium, magnesium and/or calcium and therapeutic failure may result. Other metallic ion-containing drugs, such as sucralfate, iron salts, and zinc salts,

  2. [Review and categorization of quinolone antibiotics].

    Science.gov (United States)

    Benes, Jirí

    2005-02-01

    No standard categorization of quinolone antibiotics into generations may be found in either Czech or world literature. The author recommends a categorization into four groups defined according to their spectrum of action and utilization: 1) preparations for the treatment of urinary tract infections; 2) systemically acting quinolones chiefly efficacious against Gram-negative bacteria; 3) so-called respiratory quinolones; and 4) quinolones with a very broad spectrum of action suitable for the treatment of very complicated infections. The author describes the chief characteristics of the most important quinolone antibiotics, including preparations either in their development stage or whose development has been prematurely interrupted because of adverse side-effects. The list includes all preparations that are or were temporarily registered in the Czech Republic.

  3. Multiple ESBL-Producing Escherichia coli Sequence Types Carrying Quinolone and Aminoglycoside Resistance Genes Circulating in Companion and Domestic Farm Animals in Mwanza, Tanzania, Harbor Commonly Occurring Plasmids.

    Science.gov (United States)

    Seni, Jeremiah; Falgenhauer, Linda; Simeo, Nabina; Mirambo, Mariam M; Imirzalioglu, Can; Matee, Mecky; Rweyemamu, Mark; Chakraborty, Trinad; Mshana, Stephen E

    2016-01-01

    The increased presence of extended-spectrum beta-lactamase (ESBL)-producing bacteria in humans, animals, and their surrounding environments is of global concern. Currently there is limited information on ESBL presence in rural farming communities worldwide. We performed a cross-sectional study in Mwanza, Tanzania, involving 600 companion and domestic farm animals between August/September 2014. Rectal swab/cloaca specimens were processed to identify ESBL-producing Enterobacteriaceae. We detected 130 (21.7%) animals carrying ESBL-producing bacteria, the highest carriage being among dogs and pigs [39.2% (51/130) and 33.1% (43/130), respectively]. The majority of isolates were Escherichia coli [93.3% (125/134)] and exotic breed type [OR (95%CI) = 2.372 (1.460-3.854), p-value ESBL carriage among animals. Whole-genome sequences of 25 ESBL-producing E. coli were analyzed for phylogenetic relationships using multi-locus sequence typing (MLST) and core genome comparisons. Fourteen different sequence types were detected of which ST617 (7/25), ST2852 (3/25), ST1303 (3/25) were the most abundant. All isolates harbored the bla CTX-M-15 allele, 22/25 carried strA and strB, 12/25 aac(6')-lb-cr, and 11/25 qnrS1. Antibiotic resistance was associated with IncF, IncY, as well as non-typable plasmids. Eleven isolates carried pPGRT46-related plasmids, previously reported from isolates in Nigeria. Five isolates had plasmids exhibiting 85-99% homology to pCA28, previously detected in isolates from the US. Our findings indicate a pan-species distribution of ESBL-producing E. coli clonal groups in farming communities and provide evidence for plasmids harboring antibiotic resistances of regional and international impact.

  4. Characterization of extended-spectrum beta-lactamase, carbapenemase, and plasmid quinolone determinants in Klebsiella pneumoniae isolates carrying distinct types of 16S rRNA methylase genes, and their association with mobile genetic elements.

    Science.gov (United States)

    Wei, Dan-Dan; Wan, La-Gen; Yu, Yang; Xu, Qun-Fei; Deng, Qiong; Cao, Xian-Wei; Liu, Yang

    2015-04-01

    Eighty-four multidrug-resistant Klebsiella pneumoniae (MDR-KP) isolates from a Chinese hospital from January to October 2012 were evaluated to characterize the coexistence of 16S rRNA methylase, extended-spectrum β-lactamase, carbapenemase, and plasmid-mediated quinolone resistance determinants and their association with mobile genetic elements. Among the 84 MDR-KP isolates studied, 19 isolates exhibited high-level resistance to amikacin mediated by the production of the 16S rRNA methylase. They carried 19 armA genes (22.9%) and three rmtB genes (3.6%). CTX-M genes were found in all of the isolates. Among these armA- or rmtB/CTX-M-producing K. pneumoniae isolates, 31.6% carried the carbapenemase genes (blaKPC-2 [26.3%], blaIMP-4 [10.5%], and blaNDM-1 [5.3%]), which made them resistant to imipenem (minimum inhibitory concentration [MIC] ≥16 mg/L). All positive strains possessed qnr-like genes (16 qnrA1, 10 qnrS1, and 7 qnrB4 genes) and 18 harbored an aac(6')-Ib-cr gene. Mobile elements ISEcp1, IS26, ISCR1, ISAba125, and sul-1 integrons were detected in 19/19 (100%), 16/19 (84.2%), 18/19 (94.7%), 9/19 (47.4%), and 18/19 (94.7%) isolates, respectively. The mobilizing elements occurred in different combinations in the study isolates. Majority of armA and qnr genes were in MDR-KP strains carrying integrons containing the ISCR1. Close to 80% of blaTEM-1 and blaSHV-12 were linked to IS26 while ≥90% of blaCTX-Ms and blaCMYs were linked to ISEcp1. ISAba125 was located upstream of blaNDM-1 and some blaCMY-2 genes. In addition, seven transconjugants were available for further analysis, and armA, qnrS1, acc(6')-Ib-cr, blaCTX-M-15, blaTEM-1, and blaNDM-1 were cotransferred. This study points to the dissemination of 16S rRNA methylase genes and the prevalence of selected elements implicated in evolution of resistance determinants in collection of clinical K. pneumoniae in China.

  5. Resistance surveillance studies: a multifaceted problem--the fluoroquinolone example.

    Science.gov (United States)

    Dalhoff, A

    2012-06-01

    This review summarizes data on the fluoroquinolone resistance epidemiology published in the previous 5 years. The data reviewed are stratified according to the different prescription patterns by either primary- or tertiary-care givers and by indication. Global surveillance studies demonstrate that fluoroquinolone- resistance rates increased in the past several years in almost all bacterial species except Staphylococcus pneumoniae and Haemophilus influenzae causing community-acquired respiratory tract infections (CARTIs), as well as Enterobacteriaceae causing community-acquired urinary tract infections. Geographically and quantitatively varying fluoroquinolone resistance rates were recorded among Gram-positive and Gram-negative pathogens causing healthcare-associated respiratory tract infections. One- to two-thirds of Enterobacteriaceae producing extended-spectrum β-lactamases (ESBLs) were fluoroquinolone resistant too, thus, limiting the fluoroquinolone use in the treatment of community- as well as healthcare-acquired urinary tract and intra-abdominal infections. The remaining ESBL-producing or plasmid-mediated quinolone resistance mechanisms harboring Enterobacteriaceae were low-level quinolone resistant. Furthermore, 10-30 % of H. influenzae and S. pneumoniae causing CARTIs harbored first-step quinolone resistance determining region (QRDR) mutations. These mutants pass susceptibility testing unnoticed and are primed to acquire high-level fluoroquinolone resistance rapidly, thus, putting the patient at risk. The continued increase in fluoroquinolone resistance affects patient management and necessitates changes in some current guidelines for the treatment of intra-abdominal infections or even precludes the use of fluoroquinolones in certain indications like gonorrhea and pelvic inflammatory diseases in those geographic areas in which fluoroquinolone resistance rates and/or ESBL production is high. Fluoroquinolone resistance has been selected among the commensal

  6. qnrD, a Novel Gene Conferring Transferable Quinolone Resistance in Salmonella enterica Serovar Kentucky and Bovismorbificans Strains of Human Origin

    DEFF Research Database (Denmark)

    Cavaco, Lina; Hasman, Henrik; Xia, S.

    2009-01-01

    In a previous study, four Salmonella isolates from humans in the Henan province of China showed reduced susceptibility to ciprofloxacin (MIC, 0.125 to 0.25 mu g/ml) but were susceptible to nalidixic acid ( MIC, 4 to 8 mu g/ml). All isolates were negative for known qnr genes ( A, B, and S), aac(6......')Ib-cr, and mutations in gyrA and parC. Plasmid DNA was extracted from all four isolates and transformed into Escherichia coli TG1 and DH10B cells by electroporation, and transformants were selected on 0.06 mu g/ml ciprofloxacin containing brain heart infusion agar plates. Resistance to ciprofloxacin...... qnrD, showed 48% similarity to qnrA1, 61% similarity to qnrB1, and 41% similarity to qnrS1. Further subcloning of the qnrD coding region into the constitutively expressed tetA gene of vector pBR322 showed that the gene conferred an increase in the MIC of ciprofloxacin by a factor of 32 ( from an MIC...

  7. Quinolone-based drugs against Toxoplasma gondii and Plasmodium spp.

    Science.gov (United States)

    Anquetin, Guillaume; Greiner, Jacques; Vierling, Pierre

    2005-09-01

    Owing to the rapid emergence of multi-resistant strains of Plasmodium spp. (the causative agents of malaria) and the limitations of drugs used against Toxoplasma gondii (an important opportunistic pathogen associated with AIDS and congenital birth defects), the discovery of new therapeutical targets and the development of new drugs are needed. The presence of the prokaryotic-like organelle in apicomplexan parasites (i.e. plastids), which comprise these major human pathogens, may represent a unique target for antibiotics against these protozoa. Quinolones which are known to be highly potent against bacteria were also found to specifically disrupt these parasites. They inhibit DNA replication by interacting with two essential bacterial type II topoisomerases, DNA gyrase and topoisomerase IV. There are some clues that quinolones act on plastids with a similar mechanism of action. After a brief presentation of plasmodium and toxoplasma dedicated to their life cycle, the chemotherapies presently used in clinics to fight against these protozoa and the potential new targets and drugs, we will focus our attention on their plastid which is one of these promising new targets. Then, we will present the various drugs and generations of quinolones, the leading molecules, and their inhibitory effects against these parasites together with their pharmacological properties that have been established from in vitro and in vivo studies. We will also discuss their possible mode of action.

  8. Clonal relationship between human and avian ciprofloxacin-resistant Escherichia coli isolates in North-Eastern Algeria.

    Science.gov (United States)

    Agabou, A; Lezzar, N; Ouchenane, Z; Khemissi, S; Satta, D; Sotto, A; Lavigne, J-P; Pantel, A

    2016-02-01

    The objectives of this study were to determine rates, patterns, and mechanisms of antibiotic resistance, and to assess connections between chicken commensal, human commensal, and pathogenic ciprofloxacin-resistant Escherichia coli isolates. All E. coli isolates collected from chickens, their farmers, and patients in the Constantine region (North-east Algeria) were analyzed for bla and plasmid-mediated quinolone resistance (PMQR) gene contents, phylogroups, Rep-PCR profiles, and multilocus sequence types. A high prevalence of resistance to fluoroquinolones (51.4 % to ciprofloxacin) was recorded in avian isolates. Of these, 22.2 % carried the aac(6')-Ib-cr gene, whereas lower resistance levels to these antibiotics were recorded in chicken farmers' isolates. None of the commensal isolates harbored the qnr, qepA, or oqxAB genes. One human pathogenic isolate was ertapenem-resistant and harbored the bla OXA-48 gene, 84 showed an extended-spectrum β-lactamase phenotype, with bla CTX-M-15 gene prevalent in 87.2 % of them. Seventy isolates were resistant to fluoroquinolones, with aac(6')-Ib-cr present in 72.8 %, qnrB in 5.7 %, and qnrS in 10 %. Three Rep-PCR profiles were common to chicken commensal and human pathogenic isolates (phylogroups D and B1; ST21, ST48, and ST471 respectively); one was found in both chicken and chicken-farmer commensal strains (D; ST108), while another profile was identified in a chicken-farmer commensal strain and a human pathogenic one (B1; ST19). These findings suggest clonal and epidemiologic links between chicken and human ciprofloxacin-resistant E. coli isolates and the important role that poultry may play in the epidemiology of human E. coli infections in the Constantine region.

  9. In vitro anti-Mycobacterium avium activities of quinolones: predicted active structures and mechanistic considerations.

    Science.gov (United States)

    Klopman, G; Li, J Y; Wang, S; Pearson, A J; Chang, K; Jacobs, M R; Bajaksouzian, S; Ellner, J J

    1994-08-01

    The relationship between the structures of quinolones and their anti-Mycobacterium avium activities has been previously derived by using the Multiple Computer-Automated Structure Evaluation program. A number of substructural constraints required to overcome the resistance of most of the strains have been identified. Nineteen new quinolones which qualify under these substructural requirements were identified by the program and subsequently tested. The results show that the substructural attributes identified by the program produced a successful a priori prediction of the anti-M. avium activities of the new quinolones. All 19 quinolones were found to be active, and 4 of them are as active or better than ciprofloxacin. With these new quinolones, the updated multiple computer-automated structure evaluation program structure-activity relationship analysis has helped to uncover additional information about the nature of the substituents at the C5 and C7 positions needed for optimal inhibitory activity. A possible explanation of drug resistance based on the observation of suicide inactivation of bacterial cytochrome P-450 by the cyclopropylamine moiety has also been proposed and is discussed in this report. Furthermore, we confirm the view that the amount of the uncharged form present in a neutral pH solution plays a crucial role in the drug's penetration ability.

  10. Non-Phenotypic Tests to Detect and Characterize Antibiotic Resistance Mechanisms in Enterobacteriaceae

    Science.gov (United States)

    Lupo, Agnese; Papp-Wallace, Krisztina M.; Sendi, Parham; Bonomo, Robert A.; Endimiani, Andrea

    2014-01-01

    In the past two decades, we have observed a rapid increase of infections due to multidrug-resistant Enterobacteriaceae. Regrettably, these isolates possess genes encoding for extended-spectrum β-lactamases (e.g., blaCTX-M, blaTEM, blaSHV) or plasmid-mediated AmpCs (e.g., blaCMY) that confer resistance to last-generation cephalosporins. Furthermore, other resistance traits against quinolones (e.g., mutations in gyrA and parC, qnr elements) and aminoglycosides (e.g., aminoglycosides modifying enzymes and 16S rRNA methylases) are also frequently co-associated. Even more concerning is the rapid increase of Enterobacteriaceae carrying genes conferring resistance to carbapenems (e.g., blaKPC, blaNDM). Therefore, the spread of these pathogens puts in peril our antibiotic options. Unfortunately, standard microbiological procedures require several days to isolate the responsible pathogen and to provide correct antimicrobial susceptibility test results. This delay impacts the rapid implementation of adequate antimicrobial treatment and infection control countermeasures. Thus, there is emerging interest in the early and more sensitive detection of resistance mechanisms. Modern non-phenotypic tests are promising in this respect, and hence, can influence both clinical outcome and healthcare costs. In this review, we present a summary of the most advanced methods (e.g., next-generation DNA sequencing, multiplex PCRs, real-time PCRs, microarrays, MALDITOF MS, and PCR/ESI MS) presently available for the rapid detection of antibiotic resistance genes in Enterobacteriaceae. Taking into account speed, manageability, accuracy, versatility, and costs, the possible settings of application (research, clinic, and epidemiology) of these methods and their superiority against standard phenotypic methods are discussed. PMID:24091103

  11. 耐喹诺酮类药物沙门菌毒力岛基因和耐药基因突变研究%Mutations of Salmonella pathogenicity island gene and QRDRs genes in quinolone-resistant Salmonella strains

    Institute of Scientific and Technical Information of China (English)

    王玉平; 康维钧

    2013-01-01

    Objective:To study the gene variations of Salmonella pathogenicity island-1 (SPI-1) genes and quinolone resistance-determining regions (QRDRs) genes in different serovars and ciprofloxacin-resistant Salomonella strains.Methods:The minimal inhibitory concentrations (MICs)for ciprofloxacin were determined u-sing the standard broth microdilution method-on 40 Salmonella strains in 6 serovars.Three SPI-1 genes and QRDRs genes were sequenced and compared in different Salmonella strains to analyze the gene mutations and the relationship with Salmonella virulence.Results:Three SPI-1 genes were detected in all the 40 Salmonella strains,but the base variations belonging to silent mutations were obse.rved in different serovars.No gene deletion or mutation was observed in SPI-1 genes,but gyrA point mutations (S83F and/or D87N/G) and parC point mutation (S87R)were observed in all the 40 ciprofloxacin-resistant strains.Conclusion:The SPI-1 gene variations showed the evolution of virulence in Salmonella.Ciprofloxacin may not induce gene sequence variation or deletion of SPI-1genes.However,the gyrA gene mutations may indicate the virulence reduction of Salmonella strains.%目的:研究耐喹诺酮类药物沙门菌毒力岛基因和喹诺酮耐药基因在不同血清型及耐环丙沙星菌株中基因变异情况.方法:对分属于6个不同血清型的40株沙门菌测定环丙沙星MIC;对沙门菌毒力岛Ⅰ的3个主要基因和喹诺酮耐药基因进行测序比对,分析其基因变异情况及与毒力的关系.结果:40株沙门菌其毒力岛Ⅰ的3个基因全部为阳性,不同血清型其基因序列存在不同程度的变异;环丙沙星耐药株喹诺酮耐药基因gyrA均发生了S83F和/或D87N/G点突变,parC基因发生了S87R的点突变.结论:毒力岛Ⅰ基因在不同血清型的变异,说明其毒力仍在进化中;环丙沙星并未引起沙门菌毒力岛基因突变或缺失,但喹诺酮耐药基因均发生了点突变,这可能与其毒力降低相关.

  12. [Role of reactive oxygen species in the bactericidal action of quinolones--inhibitors of DNA gyrase].

    Science.gov (United States)

    Kotova, V Iu; Mironov, A S; Zavigel'skiĭ, G B

    2014-01-01

    Quinolone antibiotics inhibit DNA gyrase, but the induced degradation of chromosomal DNA is determined by a complex process of joint action quinolones and hydroxyl radical OH'. To quantify the level of stress responses and their time dependence in bacterial cells the induced specific lux-biosensors--the bacterium Escherichia coli, containing hybrid plasmids pColD'::lux; pSoxS'::lux; pKatG'::lux were used in this study. It is shown that quinolones (nalidixic acid, norfloxacin) induce SOS-response and oxidative stress with the formation of superoxide anion O2(-) in E. coli cells. The main parameters of SOS-response and oxidative stress, which depend on the quinolone concentration, are determined. Formation of superoxide anion O2(-) occurs almost simultaneously with the SOS-response. The mutant strain of E. coli sodA sodB, which do not contain active forms of superoxide dismutases SodA and SodB, is characterized by an increased resistance to quinolones as compared to the wild type cells. At high concentrations of quinolones (nalidixic acid-->20 μg/mL; norfloxacin-->500 ng/mL) their bactericidal effect is partially caused by conversion of the superoxide anion to hydrogen peroxide H2O2, conducted by superoxide dismutases SodA and SodB, which is followed by the Fenton reaction and the formation of toxic hydroxyl radical OH'. At low concentrations of quinolones (nalidixic acid--<20 μg/mL; norfloxacin--<500 ng/mL), the role of active oxygen species in the antimicrobial effect is practically nonexistent.

  13. A spatial approach for the epidemiology of antibiotic use and resistance in community-based studies: the emergence of urban clusters of Escherichia coli quinolone resistance in Sao Paulo, Brasil

    Directory of Open Access Journals (Sweden)

    Bailey Trevor C

    2011-02-01

    Full Text Available Abstract Background Population antimicrobial use may influence resistance emergence. Resistance is an ecological phenomenon due to potential transmissibility. We investigated spatial and temporal patterns of ciprofloxacin (CIP population consumption related to E. coli resistance emergence and dissemination in a major Brazilian city. A total of 4,372 urinary tract infection E. coli cases, with 723 CIP resistant, were identified in 2002 from two outpatient centres. Cases were address geocoded in a digital map. Raw CIP consumption data was transformed into usage density in DDDs by CIP selling points influence zones determination. A stochastic model coupled with a Geographical Information System was applied for relating resistance and usage density and for detecting city areas of high/low resistance risk. Results E. coli CIP resistant cluster emergence was detected and significantly related to usage density at a level of 5 to 9 CIP DDDs. There were clustered hot-spots and a significant global spatial variation in the residual resistance risk after allowing for usage density. Conclusions There were clustered hot-spots and a significant global spatial variation in the residual resistance risk after allowing for usage density. The usage density of 5-9 CIP DDDs per 1,000 inhabitants within the same influence zone was the resistance triggering level. This level led to E. coli resistance clustering, proving that individual resistance emergence and dissemination was affected by antimicrobial population consumption.

  14. Characteristics of cefotaxime-resistant Escherichia coli from wild birds in the Netherlands.

    Science.gov (United States)

    Veldman, Kees; van Tulden, Peter; Kant, Arie; Testerink, Joop; Mevius, Dik

    2013-12-01

    Cloacal swabs from carcasses of Dutch wild birds obtained in 2010 and 2011 were selectively cultured on media with cefotaxime to screen for the presence of extended-spectrum β-lactamase (ESBL)/AmpC-producing Escherichia coli. Subsequently, all cefotaxime-resistant E. coli isolates were tested by broth microdilution and microarray. The presence of ESBL/AmpC and coexisting plasmid-mediated quinolone resistance (PMQR) genes was confirmed by PCR and sequencing. To determine the size of plasmids and the location of ESBL and PMQR genes, S1 pulsed-field gel electrophoresis (PFGE) was performed on transformants, followed by Southern blot hybridization. The study included 414 cloacal swabs originating from 55 different bird species. Cefotaxime-resistant E. coli isolates were identified in 65 birds (15.7%) from 21 different species. In all, 65 cefotaxime-resistant E. coli ESBL/AmpC genes were detected, mainly comprising variants of blaCTX-M and blaCMY-2. Furthermore, PMQR genes [aac(6')-lb-cr, qnrB1, and qnrS1] coincided in seven cefotaxime-resistant E. coli isolates. Overall, replicon typing of the ESBL/AmpC-carrying plasmids demonstrated the predominant presence of IncI1 (n = 31) and variants of IncF (n = 18). Our results indicate a wide dissemination of ESBL and AmpC genes in wild birds from The Netherlands, especially among aquatic-associated species (waterfowl, gulls, and waders). The identified genes and plasmids reflect the genes found predominantly in livestock animals as well as in humans.

  15. Presence of multi-drug resistant pathogenic Escherichia coli in the San Pedro River located in the State of Aguascalientes, Mexico.

    Directory of Open Access Journals (Sweden)

    Flor Yazmin Ramirez Castillo

    2013-06-01

    Full Text Available Contamination of surface waters in developing countries is a great concern. Treated and untreated wastewaters have been discharged into rivers and streams, leading to possible waterborne infection outbreaks and may represent a significant dissemination mechanism of antibiotic resistance genes. In this study, the water quality of San Pedro River, the main river and pluvial collector of the Aguascalientes State, Mexico was assessed. Thirty sample locations were tested throughout the River. The main physicochemical parameters of water were evaluated. Results showed high levels of fecal pollution as well as inorganic and organic matter abundant enough to support the heterotrophic growth of microorganisms. These results indicate poor water quality in samples from different locations. One hundred and fifty Escherichia coli were collected and screened by PCR for several virulence genes. Isolates were classified as either pathogenic (n = 91 or commensal (n = 59. The disc diffusion method was used to determine antimicrobial susceptibility to 13 antibiotics. Fifty-two percent of the isolates were resistant to at least one antimicrobial agent and 30.6% were multi-resistant. Eighteen E. coli strains were quinolone resistant of which 16 were multi-resistant. Plasmid-mediated quinolone resistance genes were detected in 12 isolates. Mutations at the Ser-83→Leu and/or Asp-87→Asn in the gyrA gene were detected as well as mutations at the Ser-80→Ile in parC. An E. coli microarray (Maxivirulence V 3.1 was used to characterize the virulence and antimicrobial resistance genes profiles of the fluoroquinolone-resistant isolates. Antimicrobial resistance genes such as blaTEM, sulI, sulII, dhfrIX, aph3 (strA and tet (B as well as integrons were found in fluoroquinolone resistance E. coli strains. The presence of potential pathogenic E. coli and antibiotic resistance in San Pedro River such as fluoroquinolone resistant E. coli could pose a potential threat to human

  16. Prevalence of Salmonella Isolates from Chicken and Pig Slaughterhouses and Emergence of Ciprofloxacin and Cefotaxime Co-Resistant S. enterica Serovar Indiana in Henan, China.

    Directory of Open Access Journals (Sweden)

    Li Bai

    Full Text Available The prevalence of Salmonella from chicken and pig slaughterhouses in Henan, China and antimicrobial susceptibility of these isolates to antibiotics was determined. From 283 chicken samples and 240 pig samples collected, 128 and 70 Salmonella isolates were recovered with an isolation rate of 45.2 and 29.2% respectively. The predominant serovars in chicken samples were S. enterica serovar Enteritidis, S. enterica serovar Hadar and S. enterica serovar Indiana, while those in pig samples were S. enterica serovar Typhimurium, S. enterica serovar Derby and S. enterica serovar Enteritidis. Resistance to ciprofloxacin was 8.6 and 10.0% for isolates from chickens and pigs respectively, whereas resistance to cefotaxime was 5.5 and 8.6%, respectively. Multidrug resistance (resistance to three or more classes of antimicrobial agent was markedly higher in pig isolates (57.1% than in chicken isolates (39.8%. Of particular concern was the detection of ciprofloxacin and cefotaxime co-resistant S. enterica serovar Indiana isolates, which pose risk to public health. All 16 S. enterica serovar Indiana isolates detected were resistant to ciprofloxacin, among which 11 were co-resistant to cefotaxime. The S. enterica serovar Indiana isolates accumulated point mutations in quinolone resistance determination regions of gyrA (S83F/D87G or S83F/D87N and parC (T57S/S80R. Two plasmid mediated quinolone resistant determinants were found with aac (6'-Ib-cr and oqxAB in 16 and 12 S. enterica serovar Indiana isolates respectively. Cefotaxime-resistance of S. enterica serovar Indiana was associated with the acquisition of a blaCTX-M-65 gene. The potential risk of ciprofloxacin and cefotaxime co-resistant S. enterica serovar Indiana infection is a significant concern due to limited alternative treatment options. Reduction of Salmonella in chicken and pig slaughterhouses, in particular, ciprofloxacin and cefotaxime co-resistant S. enterica serovar Indiana will be an important

  17. 感染性心内膜炎患者表皮葡萄球菌感染状况及喹诺酮类药物耐药机制研究%Staphylococcus epidermidis infection status and quinolones resistance mechanism of patients with infective endocarditis

    Institute of Scientific and Technical Information of China (English)

    李徽; 王春彤; 赵占秋; 郭晓红; 高春明

    2016-01-01

    OBJECTIVE To study Staphylococcus epidermidis infection status and quinolones resistance mechanism of patients with infective endocarditis ,so as to provide references for the selection of clinical antibacterial drugs of S .epidermis .METHODS A total of 132 cases patients with infective endocarditis in the hospital from Jan .2014 to Dec .2015 were selected .The blood specimens were collected ,pathogens were cultured and separated ,drug sensitive test was carried ,minimum inhibitory concentration (MIC) was determined ,drug resistance of S .epi-dermidis to quinolones were detected ,gyrA gene was amplified and sequenced by PCR ,and the results were ana-lyzed .RESULTS Totally 36 cases of patients occurred S .epidermidis infection in 123 cases of patients ,with the infection rate of 27 .27% .The drug resistant rate of S .epidermidis to norfloxacin was 100 .00% .The length of PCR amplification of gyrA gene product was 275bp .Some of the strains had multiple-point mutations at the same time .CONCLUSION S .epidermidis is a major pathogen causing infective endocarditis .For the majority of quino-lones is widespread drug resistance .Resistant S .epidermidis exists gyrA gene variation .Drug resistant S .epi-dermidis exists gyrA gene variant ,and this may be one of the mechanisms of resistance to quinolones .%目的:研究感染性心内膜炎患者表皮葡萄球菌感染状况及喹诺酮类药物耐药机制,为表皮葡萄球菌临床抗菌用药的选择提供参考。方法选取医院2014年1月—2015年12月诊治132例感染性心内膜炎患者,采集血液标本,培养分离感染病原菌,进行药敏试验及最低抑菌浓度(M IC )测定,检测表皮葡萄球菌对喹诺酮类抗菌药物的耐药性,同时采用PCR扩增gyrA基因及测序,分析结果。结果132例患者有36例分离出表皮葡萄球菌,感染率为27.27%;表皮葡萄球菌对诺氟沙星耐药率为100.00%;表皮葡萄球菌 PCR

  18. Fluorescence quenching as a tool to investigate quinolone antibiotic interactions with bacterial protein OmpF.

    Science.gov (United States)

    Neves, Patrícia; Sousa, Isabel; Winterhalter, Mathias; Gameiro, Paula

    2009-02-01

    The outer membrane porin OmpF is an important protein for the uptake of antibiotics through the outer membrane of gram-negative bacteria; however, the possible binding sites involved in this uptake are still not recognized. Determination, at the molecular level, of the possible sites of antibiotic interaction is very important, not only to understand their mechanism of action but also to unravel bacterial resistance. Due to the intrinsic OmpF fluorescence, attributed mainly to its tryptophans (Trp(214), Trp(61)), quenching experiments were used to assess the site(s) of interaction of some quinolone antibiotics. OmpF was reconstituted in different organized structures, and the fluorescence quenching results, in the presence of two quenching agents, acrylamide and iodide, certified that acrylamide quenches Trp(61) and iodide Trp(214). Similar data, obtained in presence of the quinolones, revealed distinct behaviors for these antibiotics, with nalidixic acid interacting near Trp(214) and moxifloxacin near Trp(61). These studies, based on straightforward and quick procedures, show the existence of conformational changes in the protein in order to adapt to the different organized structures and to interact with the quinolones. The extent of reorganization of the protein in the presence of the different quinolones allowed an estimate on the sites of protein/quinolone interaction.

  19. Characterization of integrons and resistance genes in multidrug-resistant Salmonella enterica isolated from meat and dairy products in Egypt.

    Science.gov (United States)

    Ahmed, Ashraf M; Shimamoto, Toshi; Shimamoto, Tadashi

    2014-10-17

    Foodborne pathogens are a leading cause of illness and death, especially in developing countries. The problem is exacerbated if bacteria attain multidrug resistance. Little is currently known about the extent of antibiotic resistance in foodborne pathogens and the molecular mechanisms underlying this resistance in Africa. Therefore, the current study was carried out to characterize, at the molecular level, the mechanism of multidrug resistance in Salmonella enterica isolated from 1600 food samples (800 meat products and 800 dairy products) collected from different street venders, butchers, retail markets and slaughterhouses in Egypt. Forty-seven out of 69 isolates (68.1%) showed multidrug resistance phenotypes to at least three classes of antimicrobials. The incidence of multidrug-resistant isolates was higher in meat products (37, 69.8%) than in dairy products (10, 62.5%). The multidrug-resistant serovars included, S. enterica serovar Typhimurium (24 isolates, 34.8%), S. enterica serovar Enteritidis, (15 isolates, 21.8%), S. enterica serovar Infantis (7 isolates, 10.1%) and S. enterica non-typable serovar (1 isolate, 1.4%). The highest resistance was to ampicillin (95.7%), then to kanamycin (93.6%), spectinomycin (93.6%), streptomycin (91.5%) and sulfamethoxazole/trimethoprim (91.5%). PCR and DNA sequencing were used to screen and characterize integrons and antibiotic resistance genes and 39.1% and 8.7% of isolates were positive for class 1 and class 2 integrons, respectively. β-lactamase-encoding genes were identified in 75.4% of isolates and plasmid-mediated quinolone resistance genes were identified in 27.5% of isolates. Finally, the florphenicol resistance gene, floR, was identified in 18.8% of isolates. PCR screening identified S. enterica serovar Typhimurium DT104 in both meat and dairy products. This is the first study to report many of these resistance genes in dairy products. This study highlights the high incidence of multidrug-resistant S. enterica in

  20. Evaluation of Quinolones for use in detection of determinants of acquired quinolone resistance, including the new transmissible resistance mechanisms (qnrA, qnrB, qnrS and aac(6')Ib-cr) in Escherichia coli and Salmonella enterica and determinations of wild type distributions

    DEFF Research Database (Denmark)

    Cavaco, Lina; Aarestrup, Frank Møller

    2009-01-01

    resistance genes, including qnrA, qnrB, qnrS, and aac(6')Ib-cr, were selected. Disk diffusion assays and MIC determinations by the agar dilution method were performed, according to CLSI standards, with nalidixic acid, flumequine, oxolinic acid, ciprofloxacin, enrofloxacin, marbofloxacin, norfloxacin...... diffusion assay was not efficient for the detection of some of the isolates carrying qnr and aac(6')Ib-cr. Transferable resistance genes would best be detected by testing for the MIC of ciprofloxacin or norfloxacin, as testing for the MICs of the other compounds would fail to detect isolates carrying aac(6...... would be maximized by screening with either ciprofloxacin or norfloxacin by both MIC determination and disk diffusion assays. Furthermore, a low concentration of ciprofloxacin (1 microg) in the disks seemed to increase the sensitivity of the disk diffusion assay....

  1. Plasmid-mediated bioaugmentation of sequencing batch reactors for enhancement of 2,4-dichlorophenoxyacetic acid removal in wastewater using plasmid pJP4.

    Science.gov (United States)

    Tsutsui, Hirofumi; Anami, Yasutaka; Matsuda, Masami; Hashimoto, Kurumi; Inoue, Daisuke; Sei, Kazunari; Soda, Satoshi; Ike, Michihiko

    2013-06-01

    Plasmid-mediated bioaugmentation was demonstrated using sequencing batch reactors (SBRs) for enhancing 2,4-dichlorophenoxyacetic acid (2,4-D) removal by introducing Cupriavidus necator JMP134 and Escherichia coli HB101 harboring 2,4-D-degrading plasmid pJP4. C. necator JMP134(pJP4) can mineralize and grow on 2,4-D, while E. coli HB101(pJP4) cannot assimilate 2,4-D because it lacks the chromosomal genes to degrade the intermediates. The SBR with C. necator JMP134(pJP4) showed 100 % removal against 200 mg/l of 2,4-D just after its introduction, after which 2,4-D removal dropped to 0 % on day 7 with the decline in viability of the introduced strain. The SBR with E. coli HB101(pJP4) showed low 2,4-D removal, i.e., below 10 %, until day 7. Transconjugant strains of Pseudomonas and Achromobacter isolated on day 7 could not grow on 2,4-D. Both SBRs started removing 2,4-D at 100 % after day 16 with the appearance of 2,4-D-degrading transconjugants belonging to Achromobacter, Burkholderia, Cupriavidus, and Pandoraea. After the influent 2,4-D concentration was increased to 500 mg/l on day 65, the SBR with E. coli HB101(pJP4) maintained stable 2,4-D removal of more than 95 %. Although the SBR with C. necator JMP134(pJP4) showed a temporal depression of 2,4-D removal of 65 % on day 76, almost 100 % removal was achieved thereafter. During this period, transconjugants isolated from both SBRs were mainly Achromobacter with high 2,4-D-degrading capability. In conclusion, plasmid-mediated bioaugmentation can enhance the degradation capability of activated sludge regardless of the survival of introduced strains and their 2,4-D degradation capacity.

  2. Vigilancia de la resistencia de Neisseria gonorrhoeae en un hospital de la provincia de Santa Fe, Argentina: 1997-2004 Resistance surveillance of Neisseria gonorrhoeae in a hospital in Santa Fe province, Argentina: 1997-2004

    Directory of Open Access Journals (Sweden)

    E. De Los A. Méndez

    2008-09-01

    Full Text Available Se determinaron los fenotipos de resistencia caracterizados por la concentración inhibitoria mínima, la difusión con discos y la producción de β-lactamasa de 434 aislamientos de Neisseria gonorrhoeae obtenidos de pacientes atendidos en el Servicio de Enfermedades de Transmisión Sexual del Hospital Dr. José María Cullen, Santa Fe, Argentina. Se realizaron pruebas de sensibilidad a los siguientes antimicrobianos: penicilina, tetraciclina, ciprofloxacina, espectinomicina, azitromicina y ceftriaxona. A tres aislamientos resistentes a ciprofloxacina se les realizó electroforesis de campo pulsado. Se destacaron tres situaciones epidemiológicas de interés: en el año 1997, alta incidencia de aislamientos con resistencia plasmídica a tetraciclina (33,3%; en el período 2002-2004, un aumento significativo de la resistencia plasmídica a penicilina (9,7% a 34,8%; y en el año 2000, la emergencia de dos de los tres primeros aislamientos con resistencia a quinolonas del país. El primer aislamiento resistente a azitromicina en nuestro hospital emerge en el 2004. Este trabajo jerarquiza el rol del Laboratorio de Microbiología Clínica en la orientación del tratamiento empírico de la gonorrea.Resistance phenotypes characterized by minimum inhibitory concentration, disk diffusion and β-lactamase production were determined in 434 isolates from patients attending the Sexually Transmitted Disease Service at Dr. José María Cullen Hospital in Santa Fe, Argentina. Susceptibility tests to penicillin, tetracycline, ciprofloxacin, espectinomycin, azithromycin and ceftriaxone were performed. Pulsed-field gel electrophoresis was conducted made to on three ciprofloxacin-resistant isolates. Epidemiologically speaking, three interesting events should be highlighted: during 1997, plasmid-mediated high level tetracycline-resistant strains were observed (33.3%; from 2002 to 2004 a significant increase of plasmid-mediated penicillin-resistant strains was

  3. [Study on the effect of Klotho gene interferred by plasmid-mediated short hairpin RNA (shRNA) on sinoatrial node pacing channel gene].

    Science.gov (United States)

    Cai, Yingying; Wang, Han; Hou, Yanbin; Fang, Chenli; Tian, Peng; Wang, Guihua; Li, Lu; Deng, Juelin

    2013-06-01

    The study was aimed to assess the effect of Klotho gene and sinoatrial node pacing channel gene (HCN4 and HCN2) for studying sick sinus syndrome, with Klotho gene under the interference of Plasmid-mediated short hairpin RNA. Twenty-five C57BL/6J mice were divided into four groups, i. e, plasmid shRNA 24h group, plasmid shRNA 12h group, sodium chloride 24h group and sodium chloride 12h group. Plasmid shRNA 50microL (1microg/microL) and sodium chloride 50microl were respectively injected according to mice vena caudalis into those in plasmid shRNA group and sodium chloride group. After 12h or 24h respectively, all mice were executed and their sinoatrial node tissues were cut. The mRNA of Klotho, HCN4 and HCN2 gene were detected by RT-PCR. The results of RT-PCR showed that Klotho, HCN4 and HCN2 mRNA levels were lower compared with those in sodium chloride 12h group after 12h interference interval. The results indicated that there might be the a certain relationship between Klotho gene and sinoatrial node pacing channel gene.

  4. Expansion and Evolution of a Virulent, Extensively Drug-Resistant (Polymyxin B-Resistant), QnrS1-, CTX-M-2-, and KPC-2-Producing Klebsiella pneumoniae ST11 International High-Risk Clone

    Science.gov (United States)

    Vitali, Lúcia; Gaspar, Gilberto Gambero; Bellissimo-Rodrigues, Fernando; Martinez, Roberto; Darini, Ana Lúcia Costa

    2014-01-01

    In this study, we report the early expansion, evolution, and characterization of a multiresistant Klebsiella pneumoniae clone that was isolated with increasing frequency from inpatients in a tertiary-care university hospital in Brazil. Seven carbapenem- and quinolone-resistant and polymyxin B-susceptible or -resistant K. pneumoniae isolates isolated between December 2012 and February 2013 were investigated. Beta-lactamase- and plasmid-mediated quinolone resistance (PMQR)-encoding genes and the genetic environment were investigated using PCR, sequencing, and restriction fragment length polymorphism (RFLP). Clonal relatedness was established using XbaI–pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and phylogenetic group characterization. Plasmid analyses included PCR-based replicon typing (PBRT) and hybridization of the S1-PFGE product, plasmid MLST, and conjugation experiments. Virulence potential was assessed by PCR by searching for 10 virulence factor-encoding genes (ureA, fimH, kfuBC, uge, wabG, magA, mrkD, allS, rmpA, and cf29a) and by phenotypic tests to analyze the hypermucoviscous phenotype. The genetic context of a multidrug-resistant and extensively drug-resistant K. pneumoniae ST11-KpI clone harboring IncFIIk-Tn4401a-blaKPC-2, qnrS1, and blaCTX-M-2 was found. Moreover, three isolates displayed high resistance to polymyxin B (MICs = 32, 32, and 128 mg/liter) as well as mucous and hypermucoviscous phenotypes. These bacteria also harbored ureA, fimH, uge, wabG, and mrkD, which code for virulence factors associated with binding, biofilm formation, and the ability to colonize and escape from phagocytosis. Our study describes the association of important coresistance and virulence factors in the K. pneumoniae ST11 international high-risk clone, which makes this pathogen successful at infections and points to the quick expansion and evolution of this multiresistant and virulent clone, leading to a pandrug-resistant phenotype and

  5. A "Double-Edged" Scaffold: Antitumor Power within the Antibacterial Quinolone.

    Science.gov (United States)

    Bisacchi, Gregory S; Hale, Michael R

    2016-01-01

    In the late 1980s, reports emerged describing experimental antibacterial quinolones having significant potency against eukaryotic Type II topoisomerases (topo II) and showing cytotoxic activity against tumor cell lines. As a result, several pharmaceutical companies initiated quinolone anticancer programs to explore the potential of this class in comparison to conventional human topo II inhibiting antitumor drugs such as doxorubicin and etoposide. In this review, we present a modern re-evaluation of the anticancer potential of the quinolone class in the context of today's predominantly pathway-based (rather than cytotoxicity-based) oncology drug R&D environment. The quinolone eukaryotic SAR is comprehensively discussed, contrasted with the corresponding prokaryotic data, and merged with recent structural biology information which is now beginning to help explain the basis for that SAR. Quinolone topo II inhibitors appear to be much less susceptible to efflux-mediated resistance, a current limitation of therapy with conventional agents. Recent advances in the biological understanding of human topo II isoforms suggest that significant progress might now be made in overcoming two other treatment-limiting disadvantages of conventional topo II inhibitors, namely cardiotoxicity and drug-induced secondary leukemias. We propose that quinolone class topo II inhibitors could have a useful future therapeutic role due to the continued need for effective topo II drugs in many cancer treatment settings, and due to the recent biological and structural advances which can now provide, for the first time, specific guidance for the design of a new class of inhibitors potentially superior to existing agents.

  6. Characterization of Salmonella Typhimurium DNA gyrase as a target of quinolones.

    Science.gov (United States)

    Kongsoi, Siriporn; Yokoyama, Kazumasa; Suprasert, Apinun; Utrarachkij, Fuangfa; Nakajima, Chie; Suthienkul, Orasa; Suzuki, Yasuhiko

    2015-08-01

    Quinolones exhibit good antibacterial activity against Salmonella spp. isolates and are often the choice of treatment for life-threatening salmonellosis due to multi-drug resistant strains. To assess the properties of quinolones, we performed an in vitro assay to study the antibacterial activities of quinolones against recombinant DNA gyrase. We expressed the S. Typhimurium DNA gyrase A (GyrA) and B (GyrB) subunits in Escherichia coli. GyrA and GyrB were obtained at high purity (>95%) by nickel-nitrilotriacetic acid agarose resin column chromatography as His-tagged 97-kDa and 89-kDa proteins, respectively. Both subunits were shown to reconstitute an ATP-dependent DNA supercoiling activity. Drug concentrations that suppressed DNA supercoiling by 50% (IC50 s) or generated DNA cleavage by 25% (CC25 s) demonstrated that quinolones highly active against S. Typhimurium DNA gyrase share a fluorine atom at C-6. The relationships between the minimum inhibitory concentrations (MICs), IC50 s and CC25 s were assessed by estimating a linear regression between two components. MICs measured against S. Typhimurium NBRC 13245 correlated better with IC50 s (R = 0.9988) than CC25 s (R = 0.9685). These findings suggest that the DNA supercoiling inhibition assay may be a useful screening test to identify quinolones with promising activity against S. Typhimurium. The quinolone structure-activity relationship demonstrated here shows that C-8, the C-7 ring, the C-6 fluorine, and N-1 cyclopropyl substituents are desirable structural features in targeting S. Typhimurium gyrase.

  7. Macrolides vs. quinolones for community-acquired pneumonia: meta-analysis of randomized controlled trials.

    Science.gov (United States)

    Skalsky, K; Yahav, D; Lador, A; Eliakim-Raz, N; Leibovici, L; Paul, M

    2013-04-01

    The relative efficacy, safety and ecological implications of macrolides vs. quinolones in the treatment of community-acquired pneumonia (CAP) are debatable. We performed a systematic review and meta-analysis of randomized controlled trials comparing any macrolide vs. any quinolone for the treatment of CAP among adult inpatients or outpatients, as monotherapy or both in combination with a beta-lactam. We did not limit inclusion by pneumonia severity, publication status, language or date of publication. The primary outcomes assessed were 30-day all-cause mortality and treatment failure. Two authors independently extracted the data. Fixed effect meta-analysis of risk ratios (RRs) with 95% confidence intervals was performed. Sixteen trials (4989 patients) fulfilling inclusion criteria were identified, mostly assessing outpatients with mild to moderate CAP. All-cause mortality was not significantly different for macrolides vs. quinolones, RR 1.03 (0.63-1.68, seven trials), with a low event rate (2%). Treatment failure was significantly lower with quinolones, RR 0.78 (0.67-0.91, 16 trials). The definition of failure used in the primary studies was not clearly representative of patients' benefit. Microbiological failure was lower with quinolones, RR 0.63 (0.49-0.81, 13 trials). All adverse events, adverse events requiring discontinuation and any premature antibiotic discontinuation were significantly more frequent with macrolides, mainly on account of gastrointestinal adverse events. Resistance development was not assessed in the trials. Randomized controlled trials show an advantage of quinolones in the treatment of CAP with regard to clinical cure without need for antibiotic modification at end of treatment and gastrointestinal adverse events. The clinical significance of this advantage is unclear.

  8. 全基因测序法分析肺炎克雷伯菌JM45株对喹诺酮类药物耐药基因%Analysis of quinolone-resistance genes in Klebsiella pneumoniae JM45 by whole genome sequencing

    Institute of Scientific and Technical Information of China (English)

    朱健铭; 姜如金; 吴康乐; 翁幸鐾; 孔海深

    2014-01-01

    OBJECTIVE To investigate the quinolone-resistance genes in pandrug-resistant K lebsiella pneumoniae JM45 and study the drug resistance mechanisms of the strain to the quinolones antibiotics .METHODS The whole genome sequencing ( completed graph)was performed by using high throughput Roche 454 sequencing approach , then the quinolone-resistance genes were analyzed ,and the molecular evolutionary analysis was performed with full-length gyrA and parC between JM45 and other 6 K .pneumoniae isolates .RESULTS A complete genome (chromosome) sequence and 2 plasmids sequences were obtained in JM45 .The size of chromosome was 5 273 812 bp (GC content :65 .8% ) ,the size of plasmid 1 was 317 156 bp (GC content :53 .0% ) ,and the size of plasmid 2 was 12 209 bp (GC content :55 .3% ) .gyrA (Feature ID :KPN_1614) and parC (Feature ID :KPN_0743) were positive in chromosome .As compared with the K .pneumoniae strains which were sensitive to quinolones ,the 83 rd codon of gyrA in JM45 changed from TCC to ATC(Ser→Ile) ,and the 80th codon of parC in JM45 changed from AGC to ATC(Ser→ Ile) .CONCLUSION Mutations of gyrA and parC in quinolone resist-ance-determining region (QRDR) play a key role in quinolone resistance of JM 45 .And the molecular evolutionary analysis of full-length gyrA and parC suggests that the closest relationship exists between JM 45 and K .pneumon-iae subsp .pneumoniae HS11286 (the same sequence) ,and that the farthest relationship exists between JM 45 and K .p neumoniae 342 .%目的:分析泛耐药肺炎克雷伯菌JM45株携带的喹诺酮类药物耐药基因,研究其对喹诺酮类药物的耐药机制。方法采用Roche454高通量测序技术对肺炎克雷伯菌JM 45株做全基因组测序(完成图),分析喹诺酮类耐药基因携带状况,再将 gy rA与p arC全长基因与其他6株肺炎克雷伯菌做分子进化分析。结果最终得到JM 45株一条完整的基因组(染色体)序列及两条质粒序列;基因组(

  9. The co-selection of fluoroquinolone resistance genes in the gut flora of Vietnamese children.

    Directory of Open Access Journals (Sweden)

    Le Thi Minh Vien

    Full Text Available Antimicrobial consumption is one of the major contributing factors facilitating the development and maintenance of bacteria exhibiting antimicrobial resistance. Plasmid-mediated quinolone resistance (PMQR genes, such as the qnr family, can be horizontally transferred and contribute to reduced susceptibility to fluoroquinolones. We performed an observational study, investigating the copy number of PMQR after antimicrobial therapy. We enrolled 300 children resident in Ho Chi Minh City receiving antimicrobial therapy for acute respiratory tract infections (ARIs. Rectal swabs were taken on enrollment and seven days subsequently, counts for Enterobacteriaceae were performed and qnrA, qnrB and qnrS were quantified by using real-time PCR on metagenomic stool DNA. On enrollment, we found no association between age, gender or location of the participants and the prevalence of qnrA, qnrB or qnrS. Yet, all three loci demonstrated a proportional increase in the number of samples testing positive between day 0 and day 7. Furthermore, qnrB demonstrated a significant increase in copy number between paired samples (p<0.001; Wilcoxon rank-sum, associated with non-fluoroquinolone combination antimicrobial therapy. To our knowledge, this is the first study describing an association between the use of non-fluoroquinolone antimicrobials and the increasing relative prevalence and quantity of qnr genes. Our work outlines a potential mechanism for the selection and maintenance of PMQR genes and predicts a strong effect of co-selection of these resistance determinants through the use of unrelated and potentially unnecessary antimicrobial regimes.

  10. Synthesis of Quinolone Analogues:7-[(2S, 4R)-2-Aminomethyl-4- hydroxypyrrolidin-1-yl] Quinolones

    Institute of Scientific and Technical Information of China (English)

    Jiu Yu LIU; Hui Yuan GUO

    2004-01-01

    New quinolone derivatives of 7-[(2S, 4R)-2-aminomethyl-4-hydroxypyrrolidin-1-yl] quinolone-3-carboxylic acids were synthesized by condensation of 7-halo substituted quinolone-3-carboxylic acids with (2S, 4R)-2-aminomethyl-4-hydroxypyrrolidine. These compounds were characterized by FAB-MS and 1H NMR.

  11. The safety of quinolones in pregnancy.

    Science.gov (United States)

    Yefet, Enav; Salim, Raed; Chazan, Bibiana; Akel, Hiba; Romano, Shabtai; Nachum, Zohar

    2014-11-01

    Quinolones and fluoroquinolones are highly efficient antibiotics. However, concerns regarding possible harmful effects have limited their use during pregnancy. Nevertheless, accumulating clinical data suggest that they may be safe during pregnancy. This review aimed to explore the mechanisms of action of the quinolones and fluoroquinolones, which set the stage for concerns regarding possible teratogenic and mutagenic effects; to clarify the clinical dilemmas that brought forth the necessity in reevaluating the use of those medications during pregnancy; and to review the accumulated data regarding their safety during pregnancy in animal models and humans.

  12. Association of iss and iucA, but not tsh, with plasmid-mediated virulence of avian pathogenic Escherichia coli.

    Science.gov (United States)

    Tivendale, Kelly A; Allen, Joanne L; Ginns, Carol A; Crabb, Brendan S; Browning, Glenn F

    2004-11-01

    Avian pathogenic Escherichia coli (APEC) is an economically important respiratory pathogen of chickens worldwide. Factors previously associated with the virulence of APEC include adhesins, iron-scavenging mechanisms, the production of colicin V (ColV), serum resistance, and temperature-sensitive hemagglutination, but virulence has generally been assessed by parenteral inoculation, which does not replicate the normal respiratory route of infection. A large plasmid, pVM01, is essential for virulence in APEC strain E3 in chickens after aerosol exposure. Here we establish the size of pVM01 to be approximately 160 kb and show that the putative virulence genes iss (increased serum survival) and tsh (temperature-sensitive hemagglutinin) and the aerobactin operon are on the plasmid. These genes were not clustered on pVM01 but, rather, were each located in quite distinct regions. Examination of APEC strains with defined levels of respiratory pathogenicity after aerosol exposure showed that both the aerobactin operon and iss were associated with high levels of virulence in APEC but that the possession of either gene was sufficient for intermediate levels of virulence. In contrast, the presence of tsh was not necessary for high levels of virulence. Thus, both the aerobactin operon and iss are associated with virulence in APEC after exposure by the natural route of infection. The similarities between APEC and extraintestinal E. coli infection in other species suggests that they may be useful models for definition of the role of these virulence genes and of other novel virulence genes that may be located on their virulence plasmids.

  13. Molecular Analysis of Ciprofloxacin Resistance Mechanisms in Malaysian ESBL-Producing Klebsiella pneumoniae Isolates and Development of Mismatch Amplification Mutation Assays (MAMA) for Rapid Detection of gyrA and parC Mutations

    Science.gov (United States)

    Mohd Yusof, Mohd Yasim; Tay, Sun Tee

    2014-01-01

    Ninety-three Malaysian extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae isolates were investigated for ciprofloxacin resistance. Two mismatch amplification mutation (MAMA) assays were developed and used to facilitate rapid detection of gyrA and parC mutations. The isolates were also screened for plasmid-mediated quinolone resistance (PMQR) genes including aac(6′)-Ib-cr, qepA, and qnr. Ciprofloxacin resistance (MICs 4– ≥ 32 μg/mL) was noted in 34 (37%) isolates, of which 33 isolates had multiple mutations either in gyrA alone (n = 1) or in both gyrA and parC regions (n = 32). aac(6′)-Ib-cr was the most common PMQR gene detected in this study (n = 61), followed by qnrB and qnrS (n = 55 and 1, resp.). Low-level ciprofloxacin resistance (MICs 1-2 μg/mL) was noted in 40 (43%) isolates carrying qnrB accompanied by either aac(6′)-Ib-cr (n = 34) or a single gyrA 83 mutation (n = 6). Ciprofloxacin resistance was significantly associated with the presence of multiple mutations in gyrA and parC regions. While the isolates harbouring gyrA and/or parC alteration were distributed into 11 PFGE clusters, no specific clusters were associated with isolates carrying PMQR genes. The high prevalence of ciprofloxacin resistance amongst the Malaysian ESBL-producing K. pneumoniae isolates suggests the need for more effective infection control measures to limit the spread of these resistant organisms in the hospital. PMID:24860827

  14. Resistance Pattern and Molecular Characterization of Enterotoxigenic Escherichia coli (ETEC) Strains Isolated in Bangladesh.

    Science.gov (United States)

    Begum, Yasmin A; Talukder, K A; Azmi, Ishrat J; Shahnaij, Mohammad; Sheikh, A; Sharmin, Salma; Svennerholm, A-M; Qadri, Firdausi

    2016-01-01

    Enterotoxigenic Escherichia coli (ETEC) is a common cause of bacterial infection leading to acute watery diarrhea in infants and young children as well as in travellers to ETEC endemic countries. Ciprofloxacin is a broad-spectrum antimicrobial agent nowadays used for the treatment of diarrhea. This study aimed to characterize ciprofloxacin resistant ETEC strains isolated from diarrheal patients in Bangladesh. A total of 8580 stool specimens from diarrheal patients attending the icddr,b Dhaka hospital was screened for ETEC between 2005 and 2009. PCR and Ganglioside GM1- Enzyme Linked Immuno sorbent Assay (ELISA) was used for detection of Heat labile (LT) and Heat stable (ST) toxins of ETEC. Antimicrobial susceptibilities for commonly used antibiotics and the minimum inhibitory concentration (MIC) of nalidixic acid, ciprofloxacin and azithromycin were examined. DNA sequencing of representative ciprofloxacin resistant strains was performed to analyze mutations of the quinolone resistance-determining region of gyrA, gyrB, parC and parE. PCR was used for the detection of qnr, a plasmid mediated ciprofloxacin resistance gene. Clonal variations among ciprofloxacin resistant (CipR) and ciprofloxacin susceptible (CipS) strains were determined by Pulsed-field gel electrophoresis (PFGE). Among 1067 (12%) ETEC isolates identified, 42% produced LT/ST, 28% ST and 30% LT alone. Forty nine percent (n = 523) of the ETEC strains expressed one or more of the 13 tested colonization factors (CFs) as determined by dot blot immunoassay. Antibiotic resistance of the ETEC strains was observed as follows: ampicillin 66%, azithromycin 27%, ciprofloxacin 27%, ceftriazone 13%, cotrimaxazole 46%, doxycycline 44%, erythromycin 96%, nalidixic acid 83%, norfloxacin 27%, streptomycin 48% and tetracycline 42%. Resistance to ciprofloxacin increased from 13% in 2005 to 34% in 2009. None of the strains was resistant to mecillinam. The MIC of the nalidixic acid and ciprofloxacin of representative Cip

  15. Resistance Pattern and Molecular Characterization of Enterotoxigenic Escherichia coli (ETEC Strains Isolated in Bangladesh.

    Directory of Open Access Journals (Sweden)

    Yasmin A Begum

    Full Text Available Enterotoxigenic Escherichia coli (ETEC is a common cause of bacterial infection leading to acute watery diarrhea in infants and young children as well as in travellers to ETEC endemic countries. Ciprofloxacin is a broad-spectrum antimicrobial agent nowadays used for the treatment of diarrhea. This study aimed to characterize ciprofloxacin resistant ETEC strains isolated from diarrheal patients in Bangladesh.A total of 8580 stool specimens from diarrheal patients attending the icddr,b Dhaka hospital was screened for ETEC between 2005 and 2009. PCR and Ganglioside GM1- Enzyme Linked Immuno sorbent Assay (ELISA was used for detection of Heat labile (LT and Heat stable (ST toxins of ETEC. Antimicrobial susceptibilities for commonly used antibiotics and the minimum inhibitory concentration (MIC of nalidixic acid, ciprofloxacin and azithromycin were examined. DNA sequencing of representative ciprofloxacin resistant strains was performed to analyze mutations of the quinolone resistance-determining region of gyrA, gyrB, parC and parE. PCR was used for the detection of qnr, a plasmid mediated ciprofloxacin resistance gene. Clonal variations among ciprofloxacin resistant (CipR and ciprofloxacin susceptible (CipS strains were determined by Pulsed-field gel electrophoresis (PFGE.Among 1067 (12% ETEC isolates identified, 42% produced LT/ST, 28% ST and 30% LT alone. Forty nine percent (n = 523 of the ETEC strains expressed one or more of the 13 tested colonization factors (CFs as determined by dot blot immunoassay. Antibiotic resistance of the ETEC strains was observed as follows: ampicillin 66%, azithromycin 27%, ciprofloxacin 27%, ceftriazone 13%, cotrimaxazole 46%, doxycycline 44%, erythromycin 96%, nalidixic acid 83%, norfloxacin 27%, streptomycin 48% and tetracycline 42%. Resistance to ciprofloxacin increased from 13% in 2005 to 34% in 2009. None of the strains was resistant to mecillinam. The MIC of the nalidixic acid and ciprofloxacin of representative

  16. Proficiency study for quinolones in egg

    NARCIS (Netherlands)

    Berendsen, B.J.A.; Stolker, A.A.M.

    2008-01-01

    Studie naar het voorkomen van quinolonen in eieren, beschrijving van de testmaterialen, evaluatie van de toegepaste methoden, resultaten en discussieThe aim of this proficiency study was to give laboratories the possibility to evaluate or demonstrate their competence for the analysis of quinolones i

  17. 产AmpC酶肺炎克雷伯菌的耐药性及基因型研究%A study on resistance and genotypes of AmpC beta-lactamase producing Klebsiella pneumoniae in Anhui province

    Institute of Scientific and Technical Information of China (English)

    朱玉林; 高帆; 张晓妮; 程君; 殷俊; 李家斌; 叶英

    2009-01-01

    Objective To identify the plasmid-mediated AmpC gene and to investigate its prevalence in Klebsiella pneumoniae strains i-solated in Anhui Province. Methods The AmpC-preducing isolates were chosen by cefoxitin and identified by the three-dimensional test. The plasmid-mediated AmpC β-lactamases were detected by multiplex PCR. The PCR products were directly sequenced and ana-lyzed. M-H agar dilution method was used to determine MIC of 17 antimicrobial agents against the AmpC positive isolates. Results Of the 180 strains,21 (11.67%) proved to be plasmid-mediated highly productive AmpC by DNA sequence test. Blast results indicated that the positive AmpC group was composed of 17 strains which carried DHA type and 4 strains which carried EBC type. DNA sequence analysis revealed three novel AmpC genotypes ( GenBank accession: FJ237366, FJ237367, and FJ237368 ). All AmpC positive isolates exhibited high resistance to the third or fourth generation cephalosporins,aminoglycosides,and quinolones. But all of them were suscep-tible to imipenem and meropenem. Conclusions The plasmid-mediated AmpC β-lactamases were found in Klebsiella pneumoniae strains isolated in Anhui Province and DHA type was dominant. Moreover, three novel AmpC genotypes were identified. The carbapene-ms are recommended to treat the AmpC-preducing isolates.%目的 了解安徽地区产AmpC酶肺炎克雷伯菌的基因型特征及耐药性.方法 对180株肺炎克雷伯菌进行头孢西丁纸片法初筛,三维实验筛选高产AmpC酶茼,PCR扩增、测序和BLAST比对分析以确定AmpC基因型,琼脂稀释法检测耐药性.结果 产AmpC酶菌株有21株(11.67%),其中DHA型17株,EBC型4株.3株EBC型为新基因(gene bank登录号为FJ237366,FJ237367,FJ237368);药敏显示产酶株除对亚胺培南与美罗培南敏感外,对其他抗菌药物均有不同程度的耐药.结论 安徽地区产AmpC酶的肺炎克雷伯菌以DHA型为主,同时存在EBC型突变株.高产AmpC酶菌的感染推荐

  18. Generation and characterization of quinolone-specific DNA aptamers suitable for water monitoring.

    Science.gov (United States)

    Reinemann, C; Freiin von Fritsch, U; Rudolph, S; Strehlitz, B

    2016-03-15

    Quinolones are antibiotics that are accredited in human and veterinary medicine but are regularly used in high quantities also in industrial livestock farming. Since these compounds are often only incompletely metabolized, significant amounts contaminate the aquatic environment and negatively impact on a variety of different ecosystems. Although there is increasing awareness of problems caused by pharmaceutical pollution, available methods for the detection and elimination of numerous pharmaceutical residues are currently inefficient or expensive. While this also applies to antibiotics that may lead to multi-drug resistance in pathogenic bacteria, aptamer-based technologies potentially offer alternative approaches for sensitive and efficient monitoring of pharmaceutical micropollutants. Using the Capture-SELEX procedure, we here describe the selection of an aptamer pool with enhanced binding qualities for fluoroquinolones, a widely used group of antibiotics in both human and veterinary medicine. The selected aptamers were shown to detect various quinolones with high specificity, while specific binding activities to structurally unrelated drugs were not detectable. The quinolone-specific aptamers bound to ofloxacin, one of the most frequently prescribed fluoroquinolone, with high affinity (KD=0.1-56.9 nM). The functionality of quinolone-specific aptamers in real water samples was demonstrated in local tap water and in effluents of sewage plants. Together, our data suggest that these aptamers may be applicable as molecular receptors in biosensors or as catcher molecules in filter systems for improved monitoring and treatment of polluted water.

  19. Characterization of Integrons and Resistance Genes in Salmonella Isolates from Farm Animals in Shandong Province, China

    Directory of Open Access Journals (Sweden)

    Xiaonan Zhao

    2017-07-01

    Full Text Available A total of 154 non-duplicate Salmonella isolates were recovered from 1,105 rectal swabs collected from three large-scale chicken farms (78/325, 24.0%, three large-scale duck farms (56/600, 9.3% and three large-scale pig farms (20/180, 11.1% between April and July 2016. Seven serotypes were identified among the 154 isolates, with the most common serotype in chickens and ducks being Salmonella enteritidis and in pigs Salmonella typhimurium. Antimicrobial susceptibility testing revealed that high antimicrobial resistance rates were observed for tetracycline (72.0% and ampicillin (69.4% in all sources. Class 1 integrons were detected in 16.9% (26/154 of these isolates and contained gene cassettes aadA2, aadA1, drfA1-aadA1, drfA12-aadA2, and drfA17-aadA5. Three β-lactamase genes were detected among the 154 isolates, and most of the isolates carried blaTEM−1(55/154, followed by blaPSE−1(14/154 and blaCTX−M−55 (11/154. Three plasmid-mediated quinolone resistance genes were detected among the 154 isolates, and most of the isolates carried qnrA (113/154, followed by qnrB (99/154 and qnrS (10/154. Fifty-four isolates carried floR among the 154 isolates. Multilocus sequence typing (MLST analysis showed that nine sequence types (STs were identified; ST11 was the most frequent genotype in chickens and ducks, and ST19 was identified in pigs. Our findings indicated that Salmonella was widespread, and the overuse of antibiotics in animals should be reduced considerably in developing countries.

  20. Whole-genome pyrosequencing of an epidemic multidrug-resistant Acinetobacter baumannii strain belonging to the European clone II group

    DEFF Research Database (Denmark)

    Iacono, M.; Villa, L.; Fortini, D.

    2008-01-01

    The whole-genome sequence of an epidemic, multidrug-resistant Acinetobacter baumannii strain (strain ACICU) belonging to the European clone II group and carrying the plasmid-mediated bla(OXA-58) carbapenem resistance gene was determined. The A. baumannii ACICU genome was compared with the genomes...

  1. Detection of quinolones in commercial eggs obtained from farms in the Espaíllat Province in the Dominican Republic.

    Science.gov (United States)

    Moscoso, S; de los Santos, F Solís; Andino, A G; Diaz-Sanchez, Sandra; Hanning, I

    2015-01-01

    Previously, we reported the use of quinolones in broiler chickens resulted in residues in retail poultry meat obtained from nine districts in the Santiago Province of the Dominican Republic. Residues in poultry products are a concern due to consumer allergies and the potential to develop antibiotic-resistant bacteria. Given the use of quinolones in poultry production and our previous findings in poultry meat, the objective of this study was to evaluate the presence of quinolone residues in eggs. Samples were collected from 48 different farms located in three of the four municipalities (Moca, Cayetano Germosén, and Jamao) of the Espaíllat Province. Each farm was sampled three times between July and September for a total of 144 samples. Samples were evaluated qualitatively and quantitatively for quinolone residues using the Equinox test. Operation systems (cage or floor), seasonality, and location were considered along with egg-producer sizes that were defined as small scale, 60,000 eggs per day. From small-, medium-, and large-scale producers, 69, 50, and 40% of samples were positive for quinolone residues, respectively. A greater number of samples were positive (61%) in floor-laying hen producers compared with those using cages (40%). In the Jamao municipality, 67% of the samples were positive compared with Moca and Cayetano Germosén, where 56 and 25% of samples were positive, respectively. Sampling time had an effect on percent positives: samples collected in July, August, and September were 71, 19, and 63% positive, respectively. Overall, 51% of the samples obtained from eggs produced in the province of Espaíllat were positive for quinolone residues at levels higher than the maximum limits for edible tissue established by the regulatory agencies, including the European Union and U.S. Department of Agriculture. The results obtained from this research confirmed the presence of quinolone residue in eggs, which may present a health risk to some consumers.

  2. Phenotypic and molecular characterization of antimicrobial resistance in Enterobacter spp. isolates from companion animals in Japan

    Science.gov (United States)

    Harada, Kazuki; Shimizu, Takae; Mukai, Yujiro; Kuwajima, Ken; Sato, Tomomi; Kajino, Akari; Usui, Masaru; Tamura, Yutaka; Kimura, Yui; Miyamoto, Tadashi; Tsuyuki, Yuzo; Ohki, Asami; Kataoka, Yasushi

    2017-01-01

    The emergence of antimicrobial resistance among Enterobacter spp., including resistance to extended-spectrum cephalosporins (ESC), is of great concern in both human and veterinary medicine. In this study, we investigated the prevalence of antimicrobial resistance among 60 isolates of Enterobacter spp., including E. cloacae (n = 44), E. aerogenes (n = 10), and E. asburiae (n = 6), from clinical specimens of dogs and cats from 15 prefectures in Japan. Furthermore, we characterized the resistance mechanisms harbored by these isolates, including extended-spectrum β-lactamases (ESBLs) and plasmid-mediated quinolone resistance (PMQR); and assessed the genetic relatedness of ESC-resistant Enterobacter spp. strains by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Antimicrobial susceptibility testing demonstrated the resistance rates to ampicillin (93.3%), amoxicillin-clavulanic acid (93.3%), cefmetazole (93.3%), chloramphenicol (46.7%), ciprofloxacin (43.3%), tetracycline (40.0%), ceftazidime (33.3%), cefotaxime (33.3%), trimethoprim/sulfamethoxazole (28.3%), gentamicin (23.3%), and meropenem (0%). Phenotypic testing detected ESBLs in 16 of 18 ESC-resistant E. cloacae isolates but not in the other species. The most frequent ESBL was CTX-M-15 (n = 8), followed by SHV-12 (n = 7), and CTX-M-3 (n = 1). As for AmpC β-lactamases, CMY-2 (n = 2) and DHA-1 (n = 2) were identified in ESC-resistant E. cloacae strains with or without ESBLs. All of the ESC-resistant E. cloacae strains also harbored one or two PMQRs, including qnrB (n = 15), aac(6’)-Ib-cr (n = 8), and qnrS (n = 2). Based on MLST and PFGE analysis, E. cloacae clones of ST591-SHV-12, ST171-CTX-M-15, and ST121-CTX-M-15 were detected in one or several hospitals. These results suggested intra- and inter-hospital dissemination of E. cloacae clones co-harboring ESBLs and PMQRs among companion animals. This is the first report on the large-scale monitoring of antimicrobial-resistant isolates

  3. Expression of the marA, soxS, acrB and ramA genes related to the AcrAB/TolC efflux pump in Salmonella entérica strains with and without quinolone resistance-determining regions gyrA gene mutations

    Directory of Open Access Journals (Sweden)

    Rafaela Gomes Ferrari

    Full Text Available Several studies have been conducted in recent years to elucidate the structure, function and significance of AcrB, MarA, SoxS and RamA in Salmonella enterica. In this study, the relative quantification of acrB, soxS, marA and ramA genes expression was evaluated in 14 strains of S. enterica, with or without accompanying mutations in the quinolone resistance-determining regions of the gyrA gene, that were exposed to ciprofloxacin during the exponential growth phase. The presence of ciprofloxacin during the log phase of bacterial growth activated the genes marA, soxS, ramA and acrB in all S. enterica strains analyzed in this study. The highest expression levels for acrB were observed in strains with gyrA mutation, and marA showed the highest expression in the strains without mutation. Considering only the strains with ciprofloxacin minimum inhibitory concentration values 0.125 [1]g/mL (low susceptibility, with and without mutations in gyrA, the most expressed gene was marA. In this study, we observed that strains resistant to nalidixic acid may express genes associated with the efflux pump and the expression of the AcrAB-TolC pump genes seems to occur independently of mutations in gyrA.

  4. Expression of the marA, soxS, acrB and ramA genes related to the AcrAB/TolC efflux pump in Salmonella entérica strains with and without quinolone resistance-determining regions gyrA gene mutations

    Directory of Open Access Journals (Sweden)

    Rafaela Gomes Ferrari

    2013-04-01

    Full Text Available Several studies have been conducted in recent years to elucidate the structure, function and significance of AcrB, MarA, SoxS and RamA in Salmonella enterica. In this study, the relative quantification of acrB, soxS, marA and ramA genes expression was evaluated in 14 strains of S. enterica, with or without accompanying mutations in the quinolone resistance-determining regions of the gyrA gene, that were exposed to ciprofloxacin during the exponential growth phase. The presence of ciprofloxacin during the log phase of bacterial growth activated the genes marA, soxS, ramA and acrB in all S. enterica strains analyzed in this study. The highest expression levels for acrB were observed in strains with gyrA mutation, and marA showed the highest expression in the strains without mutation. Considering only the strains with ciprofloxacin minimum inhibitory concentration values 0.125 [1]g/mL (low susceptibility, with and without mutations in gyrA, the most expressed gene was marA. In this study, we observed that strains resistant to nalidixic acid may express genes associated with the efflux pump and the expression of the AcrAB-TolC pump genes seems to occur independently of mutations in gyrA.

  5. Expression of the marA, soxS, acrB and ramA genes related to the AcrAB/TolC efflux pump in Salmonella enterica strains with and without quinolone resistance-determining regions gyrA gene mutations.

    Science.gov (United States)

    Ferrari, Rafaela Gomes; Galiana, Antonio; Cremades, Rosa; Rodríguez, Juan Carlos; Magnani, Marciane; Tognim, Maria Cristina Bronharo; Oliveira, Tereza C R M; Royo, Gloria

    2013-01-01

    Several studies have been conducted in recent years to elucidate the structure, function and significance of AcrB, MarA, SoxS and RamA in Salmonella enterica. In this study, the relative quantification of acrB, soxS, marA and ramA genes expression was evaluated in 14 strains of S. enterica, with or without accompanying mutations in the quinolone resistance-determining regions of the gyrA gene, that were exposed to ciprofloxacin during the exponential growth phase. The presence of ciprofloxacin during the log phase of bacterial growth activated the genes marA, soxS, ramA and acrB in all S. enterica strains analyzed in this study. The highest expression levels for acrB were observed in strains with gyrA mutation, and marA showed the highest expression in the strains without mutation. Considering only the strains with ciprofloxacin minimum inhibitory concentration valuesmarA. In this study, we observed that strains resistant to nalidixic acid may express genes associated with the efflux pump and the expression of the AcrAB-TolC pump genes seems to occur independently of mutations in gyrA.

  6. Detection of quinolones in poultry meat obtained from retail centers in Santiago Province, the Dominican Republic.

    Science.gov (United States)

    Silfrany, R O; Caba, R E; Solís de Los Santos, F; Hanning, I

    2013-02-01

    In the Dominican Republic, poultry consumption per capita is greater than 34 kg of poultry meat per year. However, antibiotics, specifically the quinolone group, may be overused and can result in residues in the poultry meat. These residues are of concern because consumers may have allergies to antibiotics and antibiotic-resistant bacteria can develop from overuse of antibiotics in production. Little is known concerning this issue specifically for Santiago Province in the Dominican Republic. Thus, the main purpose of this research was to evaluate the incidence of residual quinolones in poultry meat and determine whether any residues detected were higher than the residue maximum limits (100 μg/kg) established by food industry authorities, including the U.S. Food and Drug Administration and European Food Safety Authority. A total of 135 samples of chicken breast were taken from different retail meat centers in the nine municipalities of Santiago Province (Santiago, Tamboril, Sabana Iglesia, Villa Bisonó, Puñal, Villa González, Licey, Jánico, and San José De Las Matas) and were analyzed using the Equinox test (Immunotec, Swanton, VT). Of the 135 samples analyzed, 50% from Sabana Iglesia, 20% from Licey, 20% from San Jose De Las Matas, and 6.25% from Santiago contained residues of quinolones higher than the residue maximum limits. No quinolone residues were detected in samples obtained from Janico, Punal, Tamboril, Villa Bisono, or Villa Gonzalez. The results of this investigation suggest that some poultry meat sold for human consumption in Santiago Province of the Dominican Republic contains quinolone residues and may represent a health risk to some consumers.

  7. Functions of a GyrBA fusion protein and its interaction with QnrB and quinolones.

    Science.gov (United States)

    Chen, Chunhui; Villet, Regis; Jacoby, George A; Hooper, David C

    2015-11-01

    In order to study the interactions between Escherichia coli DNA gyrase and the gyrase interacting protein QnrB in vivo, we constructed a gyrB-gyrA fusion and validated its ability to correct the temperature-sensitive growth of gyrA and gyrB mutants. Like wild-type gyrA, the gyrB-gyrA fusion complemented a quinolone-resistant gyrA mutant to increase susceptibility. It functioned as an active type II topoisomerase, catalyzed negative supercoiling of DNA, was inhibited by quinolone, and was protected by QnrB.

  8. Looking for the new preparations for antibacterial therapy III. New antimicrobial agents from the quinolones group in clinical trials.

    Science.gov (United States)

    Karpiuk, Izabela; Tyski, Stefan

    2013-01-01

    There is an essential need for searching for the new compounds effective in the treatment of infections caused by multidrug-resistant bacteria. This paper is the third part of a series associated with the exploration of new antibacterial agents and it discusses the compounds belonging to the group of quinolones and substances possessing a hybrid structure composed of the quinolone molecule and other compounds. Eleven new substances at the stage of clinical trials are presented. Three of them belong to the group of non-fluorinated quinolone (nemonoxacin, ozenoxacin and KRP-AM 1977X), while six are the quinolones containing fluorine atom at 6 position of the carbon atom in the quinoline ring (zabofloxacin, finafloxacin, delafloxacin, JNJ-Q2, WCK771 and KPI-10). The remaining two compounds possess a hybrid construction composed of the quinolone structure and other molecules (cadazolid and CBR-2092). There is a chance in the near future, that the presented compounds can extend the range of existing antibacterial drugs and provide an alternative to currently available medicinal products.

  9. Antistaphylococcal activity of DX-619, a new des-F(6)-quinolone, compared to those of other agents.

    Science.gov (United States)

    Bogdanovich, Tatiana; Esel, Duygu; Kelly, Linda M; Bozdogan, Bülent; Credito, Kim; Lin, Gengrong; Smith, Kathy; Ednie, Lois M; Hoellman, Dianne B; Appelbaum, Peter C

    2005-08-01

    The in vitro activity of DX-619, a new des-F(6)-quinolone, was tested against staphylococci and compared to those of other antimicrobials. DX-619 had the lowest MIC ranges/MIC(50)s/MIC(90)s (microg/ml) against 131 Staphylococcus aureus strains (32), and ciprofloxacin (>32/>32). Raised quinolone MICs were associated with mutations in GyrA (S84L) and single or double mutations in GrlA (S80F or Y; E84K, G, or V) in all S. aureus strains tested. A recent vancomycin-resistant S. aureus (VRSA) strain (Hershey) was resistant to available quinolones and was inhibited by DX-619 at 0.25 microg/ml and sitafloxacin at 1.0 microg/ml. Vancomycin (except VRSA), linezolid, ranbezolid, tigecycline, and quinupristin-dalfopristin were active against all strains, and teicoplanin was active against S. aureus but less active against coagulase-negative staphylococci. DX-619 produced resistant mutants with MICs of 1 to >32 microg/ml after 32 microg/ml for ciprofloxacin, sitafloxacin, moxifloxacin, and gatifloxacin. DX-619 and sitafloxacin were also more active than other tested drugs against selected mutants and had the lowest mutation frequencies in single-step resistance selection. DX-619 and sitafloxacin were bactericidal against six quinolone-resistant (including the VRSA) and seven quinolone-susceptible strains tested, whereas gatifloxacin, moxifloxacin, levofloxacin, and ciprofloxacin were bactericidal against 11, 10, 7, and 5 strains at 4x MIC after 24 h, respectively. DX-619 was also bactericidal against one other VRSA strain, five vancomycin-intermediate S. aureus strains, and four vancomycin-intermediate coagulase-negative staphylococci. Linezolid, ranbezolid, and tigecycline were bacteriostatic and quinupristin-dalfopristin, teicoplanin, and vancomycin were bactericidal against two, eight, and nine strains, and daptomycin and oritavancin were rapidly bactericidal against all strains, including the VRSA. DX-619 has potent in vitro activity against staphylococci, including

  10. Endochin optimization: structure-activity and structure-property relationship studies of 3-substituted 2-methyl-4(1H)-quinolones with antimalarial activity.

    Science.gov (United States)

    Cross, R Matthew; Monastyrskyi, Andrii; Mutka, Tina S; Burrows, Jeremy N; Kyle, Dennis E; Manetsch, Roman

    2010-10-14

    Since the 1940s endochin and analogues thereof were known to be causal prophylactic and potent erythrocytic stage agents in avian models. Preliminary screening in a current in vitro assay identified several 4(1H)-quinolones with nanomolar EC(50) against erythrocytic stages of multidrug resistant W2 and TM90-C2B isolates of Plasmodium falciparum. Follow-up structure-activity relationship (SAR) studies on 4(1H)-quinolone analogues identified several key features for biological activity. Nevertheless, structure-property relationship (SPR) studies conducted in parallel revealed that 4(1H)-quinolone analogues are limited by poor solubilities and rapid microsomal degradations. To improve the overall efficacy, multiple 4(1H)-quinolone series with varying substituents on the benzenoid quinolone ring and/or the 3-position were synthesized and tested for in vitro antimalarial activity. Several structurally diverse 6-chloro-2-methyl-7-methoxy-4(1H)-quinolones with EC(50) in the low nanomolar range against the clinically relevant isolates W2 and TM90-C2B were identified with improved physicochemical properties while maintaining little to no cross-resistance with atovaquone.

  11. The selection of resistance to and the mutagenicity of different fluoroquinolones in Staphylococcus aureus and Streptococcus pneumoniae.

    Science.gov (United States)

    Sierra, J M; Cabeza, J G; Ruiz Chaler, M; Montero, T; Hernandez, J; Mensa, J; Llagostera, M; Vila, J

    2005-09-01

    Two quinolone-susceptible Staphylococcus aureus and five quinolone-susceptible Streptococcus pneumoniae isolates were used to obtain in-vitro quinolone-resistant mutants in a multistep resistance selection process. The fluoroquinolones used were ciprofloxacin, moxifloxacin, levofloxacin, gemifloxacin, trovafloxacin and clinafloxacin. The mutagenicity of these quinolones was determined by the Salmonella and the Escherichia coli retromutation assays. All quinolone-resistant Staph. aureus mutants had at least one mutation in the grlA gene, while 86.6% of quinolone-resistant Strep. pneumoniae mutants had mutations in either or both the gyrA and parC genes. Moxifloxacin and levofloxacin selected resistant mutants later than the other quinolones, but this difference was more obvious in Staph. aureus. Accumulation of the fluoroquinolones by Staph. aureus did not explain these differences, since levofloxacin and moxifloxacin accumulated inside bacteria to the same extent as clinafloxacin and trovafloxacin. The results also showed that moxifloxacin and levofloxacin had less mutagenic potency in both mutagenicity assays, suggesting a possible relationship between the selection of resistance to quinolones and the mutagenic potency of the molecule. Furthermore, gemifloxacin selected efflux mutants more frequently than the other quinolones used. Thus, the risk of developing quinolone resistance may depend on the density of the microorganism at the infection site and the concentration of the fluoroquinolone, and also on the mutagenicity of the quinolone used, with moxifloxacin and levofloxacin being the least mutagenic.

  12. High-Quality Genome Sequence of an Escherichia coli O157 Strain Carrying an mcr-1 Resistance Gene Isolated from a Patient in the United States.

    Science.gov (United States)

    Lindsey, Rebecca L; Batra, Dhwani; Rowe, Lori; Loparev, Vladimir N; Stripling, Devon; Garcia-Toledo, Lisley; Knipe, Kristen; Juieng, Phalasy; Sheth, Mili; Martin, Haley; Laufer Halpin, Alison

    2017-03-16

    Enterobacteriaceae carrying plasmid-mediated colistin resistance have been found around the world. We report here the high-quality whole-genome sequence of an Escherichia coli O157:H48 isolate (2016C-3936C1) from Connecticut that carried the mcr-1 resistance gene on an IncX4-type plasmid. Copyright © 2017 Lindsey et al.

  13. Niveles de resistencia a quinolonas y otros antimicrobianos en cepas de Escherichia coli comensales en niños de la zona periurbana de Lima, Perú Levels of quinolones resistance and other antimicrobial in non-pathogenic Escherichia coli strains in children from the periurban area of Lima, Peru

    Directory of Open Access Journals (Sweden)

    María J. Pons

    2012-03-01

    Full Text Available El objetivo principal del estudio fue establecer el nivel de resistencia a antimicrobianos en un total de 222 cepas comensales de E. coli de origen fecal, en Perú. Las frecuencias de resistencia encontrados, frente los antimicrobianos evaluados, fueron: ampicilina (62,6%, cotrimoxazol (48,6%, tetraciclina (43,0% y cloranfenicol (15,8%. Destacan los elevados niveles de resistencia a quinolonas: 32% al ácido nalidíxico (NAL y 12% a ciprofloxacino (CIP. Estos elevados niveles hacia las quinolonas en cepas comensales aisladas en niños de esta franja de edad, realzan el uso extendido y el impacto de consumo de este tipo de antimicrobianos en la comunidad, mostrando el riesgo potencial de su pérdida de utilidad en el área.The main aim of this study was to establish the resistance levels to antimicrobial agents, in 222 non-pathogenic E. coli strains of fecal origin in Peru. The proportion of resistance found to the evaluated antimicrobials was ampicillin (62.6%, cotrimoxazole (48,6%, tetracycline (43,0% and chloramphenicol (15,8%. We emphasize the high resistance levels found for quinolones: 32% for nalidixic acid (NAL and 12% for ciprofloxacin (CIP. These high levels of quinoloneresistance in non-pathogenic strains isolated from children in this age group highlight the extensive use and the impact of the intake of this kind of antimicrobials in the community, showing the potential risk of the loss of their utility in the area.

  14. Phenotypic and Molecular Characterization of Antimicrobial Resistance in Klebsiella spp. Isolates from Companion Animals in Japan: Clonal Dissemination of Multidrug-Resistant Extended-Spectrum β-Lactamase-Producing Klebsiella pneumoniae.

    Science.gov (United States)

    Harada, Kazuki; Shimizu, Takae; Mukai, Yujiro; Kuwajima, Ken; Sato, Tomomi; Usui, Masaru; Tamura, Yutaka; Kimura, Yui; Miyamoto, Tadashi; Tsuyuki, Yuzo; Ohki, Asami; Kataoka, Yasushi

    2016-01-01

    The emergence of antimicrobial resistance in Klebsiella spp., including resistance to extended-spectrum cephalosporins (ESC) and fluoroquinolones, is of great concern in both human and veterinary medicine. In this study, we investigated the prevalence of antimicrobial resistance in a total of 103 Klebsiella spp. isolates, consisting of Klebsiella pneumoniae complex (KP, n = 89) and K. oxytoca (KO, n = 14) from clinical specimens of dogs and cats in Japan. Furthermore, we characterized the resistance mechanisms, including extended-spectrum β-lactamase (ESBL), plasmid-mediated AmpC β-lactamase (PABL), and plasmid-mediated quinolone resistance (PMQR); and assessed genetic relatedness of ESC-resistant Klebsiella spp. strains by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Antimicrobial susceptibility testing demonstrated that resistance rates to ampicillin, cephalothin, enrofloxacin, ciprofloxacin, trimethoprim/sulfamethoxazole, cefotaxime, gentamicin, tetracycline, chloramphenicol, amoxicillin-clavulanic acid, and cefmetazole were 98.1, 37.9, 37.9, 35.9, 35.0, 34.0, 31.1, 30.1, 28.2, 14.6, and 6.8%, respectively. Phenotypic testing detected ESBLs and/or AmpC β-lactamases in 31 of 89 (34.8%) KP isolates, but not in KO isolates. Resistances to 5 of the 12 antimicrobials tested, as well as the three PMQRs [qnrB, qnrS, and aac(6')-Ib-cr], were detected significantly more frequently in ESBL-producing KP, than in non-ESBL-producing KP and KO. The most frequent ESBL was CTX-M-15 (n = 13), followed by CTX-M-14 (n = 7), CTX-M-55 (n = 6), SHV-2 (n = 5), CTX-M-2 (n = 2), and CTX-M-3 (n = 2). Based on the rpoB phylogeny, all ESBL-producing strains were identified as K. pneumoniae, except for one CTX-M-14-producing strain, which was identified as K. quasipneumoniae. All of AmpC β-lactamase positive isolates (n = 6) harbored DHA-1, one of the PABLs. Based on MLST and PFGE analysis, ST15 KP clones producing CTX-M-2, CTX-M-15, CTX-M-55, and

  15. Metal Complexes of Quinolone Antibiotics and Their Applications: An Update

    Directory of Open Access Journals (Sweden)

    Valentina Uivarosi

    2013-09-01

    Full Text Available Quinolones are synthetic broad-spectrum antibiotics with good oral absorption and excellent bioavailability. Due to the chemical functions found on their nucleus (a carboxylic acid function at the 3-position, and in most cases a basic piperazinyl ring (or another N-heterocycle at the 7-position, and a carbonyl oxygen atom at the 4-position quinolones bind metal ions forming complexes in which they can act as bidentate, as unidentate and as bridging ligand, respectively. In the polymeric complexes in solid state, multiple modes of coordination are simultaneously possible. In strongly acidic conditions, quinolone molecules possessing a basic side nucleus are protonated and appear as cations in the ionic complexes. Interaction with metal ions has some important consequences for the solubility, pharmacokinetics and bioavailability of quinolones, and is also involved in the mechanism of action of these bactericidal agents. Many metal complexes with equal or enhanced antimicrobial activity compared to the parent quinolones were obtained. New strategies in the design of metal complexes of quinolones have led to compounds with anticancer activity. Analytical applications of complexation with metal ions were oriented toward two main directions: determination of quinolones based on complexation with metal ions or, reversely, determination of metal ions based on complexation with quinolones.

  16. Metal complexes of quinolone antibiotics and their applications: an update.

    Science.gov (United States)

    Uivarosi, Valentina

    2013-09-11

    Quinolones are synthetic broad-spectrum antibiotics with good oral absorption and excellent bioavailability. Due to the chemical functions found on their nucleus (a carboxylic acid function at the 3-position, and in most cases a basic piperazinyl ring (or another N-heterocycle) at the 7-position, and a carbonyl oxygen atom at the 4-position) quinolones bind metal ions forming complexes in which they can act as bidentate, as unidentate and as bridging ligand, respectively. In the polymeric complexes in solid state, multiple modes of coordination are simultaneously possible. In strongly acidic conditions, quinolone molecules possessing a basic side nucleus are protonated and appear as cations in the ionic complexes. Interaction with metal ions has some important consequences for the solubility, pharmacokinetics and bioavailability of quinolones, and is also involved in the mechanism of action of these bactericidal agents. Many metal complexes with equal or enhanced antimicrobial activity compared to the parent quinolones were obtained. New strategies in the design of metal complexes of quinolones have led to compounds with anticancer activity. Analytical applications of complexation with metal ions were oriented toward two main directions: determination of quinolones based on complexation with metal ions or, reversely, determination of metal ions based on complexation with quinolones.

  17. Regional variations in quinolone use in France and associated factors.

    Science.gov (United States)

    Gallini, A; Taboulet, F; Bourrel, R

    2012-11-01

    The purpose of this study was to investigate geographic variations in the use of quinolones in France and their associated factors. All reimbursement claims of antimicrobials were collected for 90 % of the French population for the year 2007. Dispensed quantities were then converted into defined daily doses (DDD) and adjusted for the age structure of the national population. Correlations between quinolone use and total antimicrobial use and some morbidity and socio-economic factors were studied using Spearman's rank correlation coefficients. On average, 2.05 DDD of quinolones per 1,000 inhabitants per day (DID) were dispensed in 2007 in France, accounting for 10.2 % of the total antimicrobial consumption in adults. A 40 % variation was observed between the regions with the lowest (1.73 DID) and the highest use (2.44 DID). This variation was more important for anti-pneumococcal quinolones than for quinolones directed against urinary tract infections (coefficients of variation: 26 vs. 6 %). Quinolone use was correlated with some regional socio-economic factors (unemployment, growth domestic product, health expenditures) and physician density, but was independent of the total antimicrobial use. After adjustment for age, large variations in quantitative and qualitative quinolone use were observed across French regions, especially for anti-pneumococcal fluoroquinolones. These results, though not controlled for potential epidemics variations, argue in favour of a possible improvement in quinolone prescribing to be achieved in some regions.

  18. Vibrational spectra study on quinolones antibiotics

    Science.gov (United States)

    Wang, Yu; Yu, Ke; Wang, Sihuan

    2006-09-01

    In order to be able to fully understand and easily identify the quilonoles, we collected IR and Raman spectra of six quinolones, and attempted to assign the attribution of the observed frequencies and their association with specific modes of vibration. According to the structure, the compounds were divided into the groups, and the similarities and differences were further studied by comparing. The result of the study shows that the frequency and intensity are comparable to the corresponding structure. The spectra not only have the commonness but also the individualities.

  19. Analysis of the gyrA gene of clinical Yersinia ruckeri isolates with reduced susceptibility to quinolones.

    Science.gov (United States)

    Gibello, Alicia; Porrero, M Concepción; Blanco, M Mar; Vela, Ana I; Liébana, Pilar; Moreno, Miguel A; Fernández-Garayzábal, José F; Domínguez, Lucas

    2004-01-01

    Antimicrobial susceptibility of seven clinical strains of Yersinia ruckeri representative of those isolated between 1994 and 2002 from a fish farm with endemic enteric redmouth disease was studied. All isolates displayed indistinguishable pulsed-field gel electrophoresis restriction patterns, indicating that they represented a single strain. However, considering both inhibition zone diameters (IZD) and MICs, the isolates recovered in 2001-2002 formed a separate cluster with lower levels of susceptibility to all the quinolones tested, especially nalidixic acid (NA) and oxolinic acid (OA), compared with the isolates recovered between 1994 and 1998. Analysis of the PCR product of the quinolone resistance-determining region of the gyrA gene from clinical isolates of Y. ruckeri with reduced susceptibility to OA and NA revealed a single amino acid substitution, Ser-83 to Arg-83 (Escherichia coli numbering). Identical substitution was observed in induced OA-resistant mutant strains, which displayed IZD and MICs of quinolones similar to those of the clinical isolates of Y. ruckeri with reduced susceptibility to these antimicrobial agents. These data indicate in that for Y. ruckeri, the substitution of Ser by Arg at position 83 of the gyrA gene is associated with reduced susceptibility to quinolones.

  20. Nitroimidazoles, Quinolones and Oxazolidinones as Fluorine Bearing Antitubercular Clinical Candidates.

    Science.gov (United States)

    Patel, Rahul V; Keum, Young-Soo; Park, Se Won

    2015-01-01

    Tuberculosis is a leading killer of lives worldwide and the global curse of multi-drug resistant tuberculosis is attaining really dangerous levels. Synergistic interaction of HIV and TB is the twin epidemics in resource-limited countries as each potentiate progression of the other. The increasing emergence of MDR-TB and XDR-TB place an immense burden for the treatment of TB with currently available drugs. The situation urgently demands for the discovery of new drugs with novel mode of action and differs in structural features in order to overcome resistance appears in conventional TB therapeutics. The present report covers the discovery of three classes of antituberculosis drugs, Nitroimidazoles, Quinolones and Oxazolidinones, undergoing clinical development with fluorine atom in their structures. Highly electronegative fluorine atom plays a signature role in advancing medicinal innovations as it existence in the drug compounds critically influences metabolic stability and lipophilicity thereby delaying its elimination by the body which results into a long term in vivo efficiency of the drug. Presence of fluorine atom(s) in the drug structures described in this report, has been associated with the several fold increase in the overall potency of the compound as demonstrated since the early discoveries. 6 Fluorinated derivatives from these three classes as pretomanid, delamanid, moxifloxacin, gatifloxacin, linezolid and sutezolid have been discussed with their antituberculosis effects, mode of action, chemical synthetic routes and results of clinical studies.

  1. Mechanisms of Reduced Susceptibility to Ciprofloxacin in Escherichia coli Isolates from Canadian Hospitals

    Directory of Open Access Journals (Sweden)

    Patricia J Baudry-Simner

    2012-01-01

    Full Text Available OBJECTIVE: To determine whether plasmid-mediated quinolone resistance (PMQR determinants play a role in the increasing resistance to fluoroquinolones among Escherichia coli isolates in Canadian hospitals, and to determine the mechanisms of reduced susceptibility to ciprofloxacin in a recent collection of 190 clinical E coli isolates.

  2. Análise da resistência às quinolonas e sulfametoxazol-trimetoprim em uroculturas positivas para Escherichia coli em infecções do trato urinário comunitárias no período de 2010 a 2014 em Itajubá – MG / Analysis of quinolones and trimethoprim-sulfamethoxazole resistance in positive Escherichia coli urucultures in urinary tract infections in a community environment from 2010 to 2014 in Itajubá – MG

    Directory of Open Access Journals (Sweden)

    Flávia\tCoura\tda\tSilva

    2017-03-01

    -se fatores importantes na antibioticorresistência, especialmente nos maiores de 65 anos e no gênero feminino. Introduction: Communitarian urinary tract infections are frequently diagnosed ambulatorily, and they are the most important cause for using antibiotic therapy. Its most common agents are gram-negative bacils from the enterobacteriaceae family, especially Escherichia coli (E. coli. Focusing on this bacterium, the empiric antibiotic therapies which are mostly used in Brazil are trimethoprim/sulfamethoxazole, quinolones, 1st and 2nd generation of cephalosporin, amoxicillin, and nitrofurantoin. Aims: Foreseeing the intense growth of antibiotic therapy resistance to these drugs shown in the world's medical literature and the importance of local medical community having knowledge of this data, this article proposes the research of quinolones and trimethoprim-sulfamethoxazole combination resistance to E. coli bacteria isolated in community-acquired UTI urocultures, from a clinical analysis laboratory, in the period from 2010 to 2014 in a southern city of the state of Minas Gerais. Methods: Retrospective and descriptive study by database research in the period from 2010 to 2014. Urocultures and antibiogram analysis were done, and the statistic calculous were made by using qui-square's test. Results: 14870 urocultures were studied. However, only 3073 samples had significant bacterial growth (bigger than 105CFU. From this result, 2203 were E. coli samples and 870 were from other bacteria. The global resistance in this 5 year study for all antibiotics was 24,46 %. Furthermore, trimethoprim-sulfamethoxazole combination resistance was 19,65% and the quinolones group was 19,2%. Through research, we have noticed an increasing resistance through these five years (p<0,0001, thus, having bigger incidence in woman and in people older than 65 years old. Conclusion: Antibiotic resistance rates almost reach unacceptable levels for therapeutic use. Age and gender demonstrated importance

  3. 喹诺酮类药物的研究进展%Research Progress of Quinolones

    Institute of Scientific and Technical Information of China (English)

    田秋月

    2014-01-01

    喹诺酮类药物是一类人工合成的抗菌药物,目前广泛应用于临床抗感染治疗中,具有较强的抗菌活性。本文主要从喹诺酮类药物的作用机制、临床应用、不良反应及耐药机制等方面进行分析和整理,综述其研究进展并对其未来的研究方向提出了建议,希望为今后喹诺酮药物的研究提供一定的参考依据。%Quinolones are a group of synthetic antibacteril drugs with strong antibacterial activity which have a broad range of clinic applications in recent years. In this article, research progress of quinolones was analyzed and summarized from the aspects of action mechanism, clinical application, adverse reactions and drug resistance mechanism, and the future research direction of quinolones was proposed.

  4. Renaissance of antibiotics against difficult infections: Focus on oritavancin and new ketolides and quinolones.

    Science.gov (United States)

    Van Bambeke, Françoise

    2014-11-01

    Lipoglycopeptide, ketolide, and quinolone antibiotics are currently in clinical development, with specific advantages over available molecules within their respective classes. The lipoglycopeptide oritavancin is bactericidal against MRSA, vancomycin-resistant enterococci, and multiresistant Streptococcus pneumoniae, and proved effective and safe for the treatment of acute bacterial skin and skin structure infection (ABSSSI) upon administration of a single 1200 mg dose (two completed phase III trials). The ketolide solithromycin (two phase III studies recruiting for community-acquired pneumonia) shows a profile of activity similar to that of telithromycin, but in vitro data suggest a lower risk of hepatotoxicity, visual disturbance, and aggravation of myasthenia gravis due to reduced affinity for nicotinic receptors. Among quinolones, finafloxacin and delafloxacin share the unique property of an improved activity in acidic environments (found in many infection sites). Finafloxacin (phase II completed; activity profile similar to that of ciprofloxacin) is evaluated for complicated urinary tract and Helicobacter pylori infections. The other quinolones (directed towards Gram-positive pathogens) show improved activity on MRSA and multiresistant S. pneumoniae compared to current molecules. They are in clinical evaluation for ABSSSI (avarofloxacin (phase II completed), nemonoxacin and delafloxacin (ongoing phase III)), respiratory tract infections (zabofloxacin and nemonoxacin (ongoing phase III)), or gonorrhea (delafloxacin).

  5. Drug-resistance mechanisms and prevalence of Enterobacter cloacae resistant to multi-antibiotics

    Institute of Scientific and Technical Information of China (English)

    张杰; 顾怡明; 俞云松; 周志慧; 杜小玲

    2004-01-01

    @@The main drug-resistance mechanism of gram-negative bacteria is producing β-lactamases. Two kinds of enzymes cause drug resistance by hydrolyzing oxyimino-cephalosporins and aztreonam: one is chromosomally encoded AmpC β-lactamases, the other is plasmid-mediated extended-spectrum β-lactamases (ESBLs). Enterobacter cloacae can produce both of them, so that these strains are seriously resistance to many antibiotics. In order to study the main drug-resistant mechanism in Enterobacter cloacae, PCR and nucleotide sequencing were performed on 58 multidrug resistant strains.

  6. Monte Carlo simulation for evaluation of the efficacy of carbapenems and new quinolones against ESBL-producing Escherichia coli.

    Science.gov (United States)

    Nakamura, Tatsuya; Shimizu, Chihiro; Kasahara, Mayumi; Okuda, Kazuyuki; Nakata, Chiyo; Fujimoto, Hiroko; Okura, Hiroe; Komatsu, Masaru; Shimakawa, Kouichi; Sueyoshi, Noriyuki; Ura, Toshiro; Satoh, Kaori; Toyokawa, Masahiro; Wada, Yasunao; Orita, Tamaki; Kofuku, Tomomi; Yamasaki, Katsutoshi; Sakamoto, Masako; Nishio, Hisaaki; Kinoshita, Shohiro; Takahashi, Hakuo

    2009-02-01

    Extended-spectrum beta-lactamase (ESBL)-producing bacteria are known to be resistant to penicillins, cephalosporins, and monobactams because of their substrate specificity, and these bacteria are sensitive only to a narrow range of antimicrobial agents. The present study was undertaken to evaluate the efficacy of carbapenems and the new quinolones against ESBL-producing Escherichia coli, using a Monte Carlo simulation based on the pharmacokinetic/pharmacodynamic (PK/PD) theory. The time above MIC (TAM, %) served as the PK/PD parameter for carbapenems, with the target level set at 40%. The AUC/MIC served as the PK/PD parameter for the new quinolones, with the target level set at more than 125. In the analysis of drug sensitivity, the MIC50 of all carbapenems other than imipenem was low (0.03 microg/ml), while the MIC50 of the new quinolones was higher (1-2 microg/ml). The probability of achieving the PK/PD target with carba penems after two doses at the usual dose level, as determined by the Monte Carlo simulation, was high for each of the carbapenems tested (99.0% for biapenem, 99.60% for meropenem, and 95.03% for doripenem), except for imipenem. Among the new quinolones, the highest probability of achieving the PK/PD target was obtained with pazufloxacin (42.90%). Thus, the results of the present study have revealed that carbapenems are effective at the regular dose and can be used as the first-choice antibiotics for ESBL-producing E. coli because the resistance ratios for carbapenems are low compared to those of the new quinolones.

  7. Microbial transformations of antimicrobial quinolones and related drugs.

    Science.gov (United States)

    Parshikov, Igor A; Sutherland, John B

    2012-12-01

    The quinolones are an important group of synthetic antimicrobial drugs used for treating bacterial diseases of humans and animals. Microorganisms transform antimicrobial quinolones (including fluoroquinolones) and the pharmacologically related naphthyridones, pyranoacridones, and cinnolones to a variety of metabolites. The biotransformation processes involve hydroxylation of methyl groups; hydroxylation of aliphatic and aromatic rings; oxidation of alcohols and amines; reduction of carboxyl groups; removal of methyl, carboxyl, fluoro, and cyano groups; addition of formyl, acetyl, nitrosyl, and cyclopentenone groups; and cleavage of aliphatic and aromatic rings. Most of these reactions greatly reduce or eliminate the antimicrobial activity of the quinolones.

  8. Actualidad de las quinolonas Present situation of quinolones

    Directory of Open Access Journals (Sweden)

    Manuel Cué Brugueras

    2005-04-01

    the addition of a piperazinyl group in position 7 and an atom of fluor in position 6 made possible the development of a series of antibacterial agents called piperazinyl fluoroquinolones, or simply fluoroquinolones . The first of them was norfloxacin, with which a greater antimicrobial activity of the group and its systemic use was achieved. For years, the fluoroquinolones were considered as an homogeneous group of antibiotics with similar characteristics and, therefore, as the second and last possibility of generation of quinilones, but the chances of transformation of their chemical structure have produced a vertiginous development of this group, which makes it the most accelerated within the antibiotics, with compounds of higher antibacterial spectrum, tissue penetration and safety and with a lower manifestation of antimicrobial resistance that has been proved up to now. At present, there are 4 generations of quinolones, their use is wider and their development continues. As a result of it, it is made a review that includes spectrum and mechanism of action, bacterial resistance, pharmacodynamics and pharmacokinetics, drug interactions, adverse effects, indications and dosage of the most used

  9. Orally bioavailable 6-chloro-7-methoxy-4(1H)-quinolones efficacious against multiple stages of Plasmodium.

    Science.gov (United States)

    Cross, R Matthew; Flanigan, David L; Monastyrskyi, Andrii; LaCrue, Alexis N; Sáenz, Fabián E; Maignan, Jordany R; Mutka, Tina S; White, Karen L; Shackleford, David M; Bathurst, Ian; Fronczek, Frank R; Wojtas, Lukasz; Guida, Wayne C; Charman, Susan A; Burrows, Jeremy N; Kyle, Dennis E; Manetsch, Roman

    2014-11-13

    The continued proliferation of malaria throughout temperate and tropical regions of the world has promoted a push for more efficacious treatments to combat the disease. Unfortunately, more recent remedies such as artemisinin combination therapies have been rendered less effective due to developing parasite resistance, and new drugs are required that target the parasite in the liver to support the disease elimination efforts. Research was initiated to revisit antimalarials developed in the 1940s and 1960s that were deemed unsuitable for use as therapeutic agents as a result of poor understanding of both physicochemical properties and parasitology. Structure-activity and structure-property relationship studies were conducted to generate a set of compounds with the general 6-chloro-7-methoxy-2-methyl-4(1H)-quinolone scaffold which were substituted at the 3-position with a variety of phenyl moieties possessing various properties. Extensive physicochemical evaluation of the quinolone series was carried out to downselect the most promising 4(1H)-quinolones, 7, 62, 66, and 67, which possessed low-nanomolar EC50 values against W2 and TM90-C2B as well as improved microsomal stability. Additionally, in vivo Thompson test results using Plasmodium berghei in mice showed that these 4(1H)-quinolones were efficacious for the reduction of parasitemia at >99% after 6 days.

  10. In Vitro Evaluation of CBR-2092, a Novel Rifamycin-Quinolone Hybrid Antibiotic: Studies of the Mode of Action in Staphylococcus aureus▿

    Science.gov (United States)

    Robertson, Gregory T.; Bonventre, Eric J.; Doyle, Timothy B.; Du, Qun; Duncan, Leonard; Morris, Timothy W.; Roche, Eric D.; Yan, Dalai; Lynch, A. Simon

    2008-01-01

    Rifamycins have proven efficacy in the treatment of persistent bacterial infections. However, the frequency with which bacteria develop resistance to rifamycin agents restricts their clinical use to antibiotic combination regimens. In a program directed toward the synthesis of rifamycins with a lower propensity to elicit resistance development, a series of compounds were prepared that covalently combine rifamycin and quinolone pharmacophores to form stable hybrid antibacterial agents. We describe mode-of-action studies with Staphylococcus aureus of CBR-2092, a novel hybrid that combines the rifamycin SV and 4H-4-oxo-quinolizine pharmacophores. In biochemical studies, CBR-2092 exhibited rifampin-like potency as an inhibitor of RNA polymerase, was an equipotent (balanced) inhibitor of DNA gyrase and DNA topoisomerase IV, and retained activity against a prevalent quinolone-resistant variant. Macromolecular biosynthesis studies confirmed that CBR-2092 has rifampin-like effects on RNA synthesis in rifampin-susceptible strains and quinolone-like effects on DNA synthesis in rifampin-resistant strains. Studies of mutant strains that exhibited reduced susceptibility to CBR-2092 further substantiated RNA polymerase as the primary cellular target of CBR-2092, with DNA gyrase and DNA topoisomerase IV being secondary and tertiary targets, respectively, in strains exhibiting preexisting rifampin resistance. In contrast to quinolone comparator agents, no strains with altered susceptibility to CBR-2092 were found to exhibit changes consistent with altered efflux properties. The combined data indicate that CBR-2092 may have potential utility in monotherapy for the treatment of persistent S. aureus infections. PMID:18443108

  11. In vitro evaluation of CBR-2092, a novel rifamycin-quinolone hybrid antibiotic: studies of the mode of action in Staphylococcus aureus.

    Science.gov (United States)

    Robertson, Gregory T; Bonventre, Eric J; Doyle, Timothy B; Du, Qun; Duncan, Leonard; Morris, Timothy W; Roche, Eric D; Yan, Dalai; Lynch, A Simon

    2008-07-01

    Rifamycins have proven efficacy in the treatment of persistent bacterial infections. However, the frequency with which bacteria develop resistance to rifamycin agents restricts their clinical use to antibiotic combination regimens. In a program directed toward the synthesis of rifamycins with a lower propensity to elicit resistance development, a series of compounds were prepared that covalently combine rifamycin and quinolone pharmacophores to form stable hybrid antibacterial agents. We describe mode-of-action studies with Staphylococcus aureus of CBR-2092, a novel hybrid that combines the rifamycin SV and 4H-4-oxo-quinolizine pharmacophores. In biochemical studies, CBR-2092 exhibited rifampin-like potency as an inhibitor of RNA polymerase, was an equipotent (balanced) inhibitor of DNA gyrase and DNA topoisomerase IV, and retained activity against a prevalent quinolone-resistant variant. Macromolecular biosynthesis studies confirmed that CBR-2092 has rifampin-like effects on RNA synthesis in rifampin-susceptible strains and quinolone-like effects on DNA synthesis in rifampin-resistant strains. Studies of mutant strains that exhibited reduced susceptibility to CBR-2092 further substantiated RNA polymerase as the primary cellular target of CBR-2092, with DNA gyrase and DNA topoisomerase IV being secondary and tertiary targets, respectively, in strains exhibiting preexisting rifampin resistance. In contrast to quinolone comparator agents, no strains with altered susceptibility to CBR-2092 were found to exhibit changes consistent with altered efflux properties. The combined data indicate that CBR-2092 may have potential utility in monotherapy for the treatment of persistent S. aureus infections.

  12. Insight into Prodrugs of Quinolones and Fluoroquinolones.

    Science.gov (United States)

    Sharma, Prabodh Chander; Piplani, Mona; Mittal, Monika; Pahwa, Rakesh

    2016-01-01

    Quinolones and fluoroquinolones are principal weapons against variety of bacterial infections and exert their antibacterial potential by interfering the activities of bacterial enzymes. As these agents are associated with some limitations, an important approach to overcome these major constraints is to prepare covalent derivatives, i.e. prodrugs. Prodrug design has been employed to improve the limitations of these drugs such as less aqueous solubility, poor absorption and distribution, toxicity, disagreeable taste, poor lipophilicity etc and for improving their pharmacological profile. This paper highlights the utility of various prodrug strategies in optimizing the therapeutic index of these antibacterial agents and their recent patents. Some of their prodrugs being utilized at preclinical and clinical levels have also been discussed. Hence, this paper has been prepared to present the significant findings of various research papers that would be helpful in motivating scientific researchers to forward the research in direction of utilization of prodrugs in clinical therapy.

  13. Oxidation of quinolones with peracids (an in situ EPR study).

    Science.gov (United States)

    Staško, Andrej; Milata, Viktor; Barbieriková, Zuzana; Brezová, Vlasta

    2014-01-01

    4-Oxoquinoline derivatives (quinolones) represent heterocyclic compounds with a variety of biological activities, along with interesting chemical reactivity. The quinolone derivatives possessing secondary amino hydrogen at the nitrogen of the enaminone system are oxidized with 3-chloroperbenzoic acid to nitroxide radicals in the primary step while maintaining their 4-pyridone ring. Otherwise, N-methyl substituted quinolones also form nitroxide radicals coupled with the opening of the 4-pyridone ring in a gradual oxidation of the methyl group via the nitrone-nitroxide spin-adduct cycle. This was confirmed in an analogous oxidation using N,N-dimethylaniline as a model compound. N-Ethyl quinolones in contrast to its N-methyl analog form only one nitroxide radical without a further degradation.

  14. New cytotoxic quinolone alkaloids from fruits of Evodia rutaecarpa.

    Science.gov (United States)

    Huang, Xin; Li, Wei; Yang, Xiu-Wei

    2012-06-01

    Three new quinolone alkaloids, 1-methyl-2-[7-hydroxy-(E)-9-tridecenyl]-4(1H)-quinolone (1), 1-methyl-2-[(Z)-4-nonenyl]-4(1H)-quinolone (2), 1-methyl-2-[(1E,5Z)-1,5-undecadienyl]-4(1H)-quinolone (3) and one new natural product, 1-methyl-2-[(E)-1-undecenyl]-4(1H)-quinolone (4), were isolated from the dried and nearly ripe fruits of Evodia rutaecarpa (Juss.) Benth., along with thirteen known compounds (5-17). In addition, one new artificial product, 1-methyl-2-[7-carbonyl-(E)-9-tridecenyl]-4(1H)-quinolone (1A) was also obtained. The structures of these compounds were determined by spectroscopic analyses. The cytotoxic activities of all of the compounds against the human cancer cell lines HL-60, N-87, H-460, and Hep G(2) cells were evaluated by MTT assay. The results showed that these alkaloids inhibited cell proliferation with IC(50) values between 14μM and 22μM.

  15. 空肠弯曲杆菌中喹诺酮类抗生素耐药基因检测与耐药性研究%Study on the Quinolone Antibiotic Resistance and Its Relative Genes in Campylobacter Jejuni

    Institute of Scientific and Technical Information of China (English)

    陈云鹏; 林雯; 邓建平

    2015-01-01

    目的:建立一种检测人粪便样本中,空肠弯曲杆菌含喹诺酮类抗生素耐药基因情况的实时荧光 PCR 方法,并对空肠弯曲杆菌对喹诺酮类抗生素耐药性与耐药基因的相关性进行初步研究。方法根据空肠弯曲杆菌对喹诺酮类抗生素耐药基因 gyrA 和 gyrB 序列设计引物,建立对应的实时荧光 PCR 方法,对79例空肠弯曲杆菌进行检测,基因扩增产物经琼脂糖凝胶电泳鉴定。以药敏试验结果作为参照标准,对两种检测方法的结果进行统计学分析,计算实时荧光 PCR 的主要技术指标。结果22例(27.8%)空肠弯曲杆菌的实时荧光 PCR 出现特异性扩增曲线,扩增产物电泳结果显示其中13例携带 gyrA 基因(59.1%),7例携带 gyrB 基因(31.8%),2例同时携带 gyrA 和 gyrB 基因(9.1%)。药敏试验显示26例空肠弯曲杆菌为环丙沙星耐药型(32.9%)。统计学分析显示,两种方法的检测结果差异无统计学意义(χ2=1.125,P >0.05),一致性较好。实时荧光 PCR 法的灵敏度和特异度分别为76.9%和96.2%,总符合率为89.9%。结论实时荧光PCR 法能够检测空肠弯曲杆菌耐药基因 gyrA 和 gyrB。耐药基因与耐药型之间有所关联,需要进一步研究。%Objective To establish a real-time fluorescence PCR method to detect the drug resistance genes of pathogenic Campylobacter jejunum in human stool samples,and investigate the relationship between quinoloneantibiotic resistance and the related genes in Campylobacter jejuni .Methods According to the gyrA and gyrB gene sequences that related with the fluoroquinolone resistance in Campylobacter jejuni ,the primers of the PCR method was designed and synthesized.A rapid real-time fluorescence PCR method to detect the drug resistance genes in Campylobacter jejuni samples was established,and the optimum reaction system and conditions were screened through an

  16. Imported poultry meat as a source of extended-spectrum cephalosporin-resistant CMY-2-producing salmonella heidelberg and s. minnesota in european union, 2014-2015.

    Science.gov (United States)

    Campos, Joana; Mourão, Joana; Silveira, Leonor; Saraiva, Margarida; Correia, Cristina Belo; Maçãs, Ana Paula; Peixe, Luísa; Antunes, Patrícia

    2017-09-14

    Extended-spectrum cephalosporin (ESC)-resistant Salmonella has been described at low level in EU, nevertheless the increasing importation of poultry meat could be an important source of epidemic strains carrying ESC-resistant genes. We evaluated ESC resistance and characterized genetic platforms as well as the clonal relatedness of Salmonella isolates from poultry meat products imported into Portugal. All Salmonella isolates recovered from samples of fresh meat destined to be imported into the EU in the scope of Portuguese official border control between 2014 and 2015 were studied. Susceptibility to antibiotics and detection of β-lactamase production was performed by disk diffusion/microdilution methods. Molecular studies included detection of genes encoding for qAmpC and extended-spectrum β-lactamases, plasmid-mediated quinolone resistance and other antibiotic resistance by PCR/sequencing and clonality by MLST and XbaI-PFGE. Plasmid characterization was assessed by conjugation assays, replicon typing (PCR-PBRT/pMLST) and hybridization experiments (I-CeuI/S1-PFGE nuclease). Salmonella belonged to S. Heidelberg (n=6; ST15/eBG26) and S. Minnesota (n=1; ST548/eBG77) serotypes and presented multidrug-resistant profiles, including to ESC and/or fluoroquinolones. All but one carried blaCMY-2 gene, located on two epidemic plasmids, IncA/C (ST2-n=5) or a transferable IncI1 (ST12-n=1). S. Heidelberg was associated with 5 PFGE-types, including one similar to an American epidemic clone. This study reveals imported poultry products as a source of uncommon and/or invasive ESC resistant Salmonella strains in EU. The increase of those clinically-relevant poultry-related serotypes in Europe, as described here, must be taken into account in the current monitoring of antibiotic resistance trends and in re-evaluation of food regulations. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  17. Clinical application of a ligation-independent pathway of multiplex ligation-dependent probe amplification for the determination of quinolone susceptibility of Streptococcus pneumoniae.

    Science.gov (United States)

    Uno, Naoki; Araki, Nobuko; Kaku, Norihito; Kosai, Kosuke; Hasegawa, Hiroo; Yanagihara, Katsunori

    2016-09-01

    We previously uncovered a ligation-independent pathway of multiplex ligation-dependent probe amplification (MLPA) through which products of MLPA could be amplified without both hybridization and ligation reactions. Here, we utilized this pathway to detect an antibiotic resistance mutation of quinolones in Streptococcus pneumoniae.

  18. Molecular Characterization and Antimicrobial Susceptibility Testing of Escherichia coli Isolates from Patients with Urinary Tract Infections in 20 Chinese Hospitals

    DEFF Research Database (Denmark)

    Cao, Xiaoli; Cavaco, Lina; Lv, Yuan

    2011-01-01

    A total of 222 urinary Escherichia coli isolates from 20 tertiary hospitals in 15 different provinces and 4 municipalities in mainland China were characterized by antimicrobial susceptibility, phylogrouping, and the presence of plasmid-mediated quinolone resistance genes. A subset of 138 suspecte...

  19. Quinolones: review of psychiatric and neurological adverse reactions.

    Science.gov (United States)

    Tomé, Ana M; Filipe, Augusto

    2011-06-01

    Quinolones are a class of antibacterial agents for the treatment of several infectious diseases (e.g. urinary and respiratory tract infections). They are used worldwide due to their broad spectrum of activity, high bioavailability and good safety profile. The safety profile varies from quinolone to quinolone. The aim of this article was to review the neurological and psychiatric adverse drug reaction (ADR) profile of quinolones, using a literature search strategy designed to identify case reports and case series. A literature search using PubMed/MEDLINE (from inception to 31 October 2010) was performed to identify case reports and case series related to quinolone-associated neurological and psychiatric ADRs. The search was conducted in two phases: the first phase was the literature search and in the second phase relevant articles were identified through review of the references of the selected articles. Relevant articles were defined as articles referring to adverse events/reactions associated with the use of any quinolone. Abstracts referring to animal studies, clinical trials and observational studies were excluded. Identified case reports were analysed by age group, sex, active substances, dosage, concomitant medication, ambulatory or hospital-based event and seriousness, after Medical Dictionary for Regulatory Activities (MedDRA®) coding. From a total of 828 articles, 83 were identified as referring to nervous system and/or psychiatric disorders induced by quinolones. 145 individual case reports were extracted from the 83 articles. 40.7% of the individual case reports belonged to psychiatric disorders only, whereas 46.9% related to neurological disorders only. Eight (5.5%) individual case reports presented both neurological and psychiatric ADRs. Ciprofloxacin, ofloxacin and pefloxacin were the quinolones with more neurological and psychiatric ADRs reported in the literature. Ciprofloxacin has been extensively used worldwide, which may explain the higher number

  20. Emergence of a colistin-resistant Escherichia coli clinical isolate harboring mcr-1 in Japan.

    Science.gov (United States)

    Tada, Tatsuya; Uechi, Kohei; Nakasone, Isamu; Shimada, Kayo; Nakamatsu, Masashi; Kirikae, Teruo; Fujita, Jiro

    2017-08-02

    The mcr-1 is a gene encoding a phosphoethanolamine transferase, which confers resistance to colistin by transferring phosphoethanolamine to lipid A. We describe here the emergence of a colistin-resistant Escherichia coli clinical isolate harboring plasmid-mediated mcr-1 in Japan. The isolate belonged to ST5702 and is suspected to come from livestock and transmitted to human. This is the first report of a clinical isolate harboring mcr-1 in Japan. Copyright © 2017. Published by Elsevier Ltd.

  1. Transconjugation and genotyping of the plasmid-mediated AmpC β-lactamase and extended-spectrum β-lactamase genes in Klebsiella pneumoniae

    Institute of Scientific and Technical Information of China (English)

    SHI Wei-feng; ZHOU Jun; QIN Jian-ping

    2009-01-01

    Backgroud AmpC β-lactamases and extended-spectrum β-lactamases (ESBLs) are becoming predominant causes of resistance to third and forth-generation cephalosporins in Klebsiella pneumoniae (K. Pneumoniae). It is very difficult to treat infectious diseases caused by multidrug-resistant K. Pneumoniae. The purpose of the present study was to investigate transconjugation and characteristics of β-lactamase genes in K. Pneumoniae producing AmpC β-lactamases and ESBLs.Methods AmpC β-lactamases were detected by three-dimension test and ESBLs by disc confirmatory test. Minimum inhibitory concentrations (MICs) were determined by agar dilution. Transfer of resistance to EC600 (Rif') was attempted by conjugation in broth and screened on agar containing cefotaxime (2 μg/ml) plus rifampin (1024 μg/ml). The genes encoding AmpC or ESBLs and their transconjugants were detected by PCR and verified by DNA sequencing. Results The resistant rates to ampicillin and piperacillin were 100% in 18 isolates of K. Pneumoniae. However, imipenem was still of great bactericidal activity on K. Pneumoniae, and its MIC50 was 0.5 μg/mL. Eleven β-lactamase genes, including TEM-1, TEM-11, SHV-13, SHV-28, CTX-M-9, CTX-M-22, CTX-M-55, OXA-1, LEN, OKP-6 and DHA-1, were found from 18 isolates. And at least one β-lactamase gene occurred in each isolate. To our surprise, there were six β-lactamase genes in the CZ04 strain. Among 18 isolates of K. Pneumoniae, the partial resistant genes in 8 isolates were conjugated successfully, which had 100% homological sequence with donors by sequence analysis. Compared with donors, 8 transconjugants had attained resistance to most β-lactams, including ampicillin, piperacillin, cefoxitin, cefotaxime and aztreonam, or even amikacin and gentamicin.Conclusions R plasmids can be easily transferred between the resistant and sensitive negative bacilli. It is very difficult to block and prevent the spread of antimicrobial resistance. So more attention should be paid

  2. [Sample preprocessing method for residual quinolones in honey using immunoaffinity resin].

    Science.gov (United States)

    Ihara, Yoshiharu; Kato, Mihoko; Kodaira, Tsukasa; Itoh, Shinji; Terakawa, Mika; Horie, Masakazu; Saito, Koichi; Nakazawa, Hiroyuki

    2009-06-01

    A sample preparation method was developed for determination of quinolones in honey using immunoaffinity resin. For this purpose, an immunoaffinity resin for quinolones was prepared by coupling a quinolone-specific monoclonal antibody to agarose resin. Honey samples diluted with phosphate buffer were reacted with immunoaffinity resin. After the resin was washed, quinolones were eluted with glycine-HCl. Quinolones in the eluate were determined by HPLC with fluorescence detection. No interfering peak was found on the chromatograms of honey samples. The recoveries of quinolones from samples were over 70% at fortification levels of 20 ng/g (for norfloxacin, ciprofloxacin and enrofloxacin) and 10 ng/g (for danofloxacin). The quantification limits of quinolones were 2 ng/g. This sample preprocessing method using immunoaffinity resin was found to be effective and suitable for determining residual quinolones in honey.

  3. Novel genetic environment of the plasmid-mediated KPC-3 gene detected in Escherichia coli and Citrobacter freundii isolates from China

    OpenAIRE

    Li, G.; Wei, Q; Wang, Y.; Du, X.; Zhao, Y.; Jiang, X.

    2010-01-01

    The imipenem and meropenem-resistant strains Citrobacter freundii HS70 and Escherichia coli HS510 were isolated from patients in Shanghai, China. By isoelectric focusing, PCR amplification and sequencing, these strains were each found to produce four β-lactamases: TEM-1, KPC-3, SHV-7 and CTX-M-14. A conjugation experiment and plasmid restriction digestion revealed that the bla KPC-3 gene was located on the same plasmid in both isolates. Bidirectional primer walking sequencing showed that the ...

  4. Antimicrobial susceptibility testing of newer quinolones against gram positive and gram negative clinical isolates.

    Science.gov (United States)

    Iffat, Wajiha; Shoaib, Muhammad Harris; Muhammad, Iyad Naeem; Rehana; Tasleem, Samiah; Gauhar, Shahnaz

    2010-07-01

    Antibiotic resistance development is an ongoing process associated with irrational antibiotic use. WHO recommends regular surveillance programs for monitoring of antibiotic resistance. The present study is a step in this direction. A total of 124 clinical isolates of Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa were collected from different hospitals in Karachi. In vitro antimicrobial susceptibility studies were carried out by agar dilution method using newer quinolones that included Gatifloxacin and Levofloxacin. It was observed that 50% (n=30) isolates of Staphylococcus aureus were resistant to gatifloxacin. Gatifloxacin was more active against Pseudomonas aeruginosa (n=23) and showing complete susceptibility with MIC 1mg/L except for three very resistant strains that shown resistance at even higher concentrations. Escherichia coli (n=45) has shown 15.5% and Klebsiella pneumoniae (n=26) 34.61% resistance to gatifloxacin. Levofloxacin was more active against Staphylococcus aureus and Escherichia coli showing complete susceptibility at 0.5 mg /L concentration. Pseudomonas aeruginosa and Klebsiella pneumoniae were found to be resistant to Levofloxacin showing 36.36% and 23.08% resistance respectively. The study strongly recommends the adherence to the antibiotic policy and regular susceptibility testing to overcome the problem associated with antimicrobial resistance.

  5. Severe pneumococcal pneumonia: impact of new quinolones on prognosis

    Directory of Open Access Journals (Sweden)

    Meybeck Agnes

    2011-03-01

    Full Text Available Abstract Background Most guidelines have been proposing, for more than 15 years, a β-lactam combined with either a quinolone or a macrolide as empirical, first-line therapy of severe community acquired pneumonia (CAP requiring ICU admission. Our goal was to evaluate the outcome of patients with severe CAP, focusing on the impact of new rather than old fluoroquinolones combined with β-lactam in the empirical antimicrobial treatments. Methods Retrospective study of consecutive patients admitted in a 16-bed general intensive care unit (ICU, between January 1996 and January 2009, for severe (Pneumonia Severity Index > or = 4 community-acquired pneumonia due to non penicillin-resistant Streptococcus pneumoniae and treated with a β-lactam combined with a fluoroquinolone. Results We included 70 patients of whom 38 received a β-lactam combined with ofloxacin or ciprofloxacin and 32 combined with levofloxacin. Twenty six patients (37.1% died in the ICU. Three independent factors associated with decreased survival in ICU were identified: septic shock on ICU admission (AOR = 10.6; 95% CI 2.87-39.3; p = 0.0004, age > 70 yrs. (AOR = 4.88; 95% CI 1.41-16.9; p = 0.01 and initial treatment with a β-lactam combined with ofloxacin or ciprofloxacin (AOR = 4.1; 95% CI 1.13-15.13; p = 0.03. Conclusion Our results suggest that, when combined to a β-lactam, levofloxacin is associated with lower mortality than ofloxacin or ciprofloxacin in severe pneumococcal community-acquired pneumonia.

  6. High Prevalence of Extended-Spectrum β-Lactamase, Plasmid-Mediated AmpC, and Carbapenemase Genes in Pet Food

    Science.gov (United States)

    Seiffert, Salome N.; Carattoli, Alessandra; Tinguely, Regula; Lupo, Agnese; Perreten, Vincent

    2014-01-01

    We evaluated the pet food contained in 30 packages as a potential origin of extended-spectrum cephalosporin-resistant Gram-negative organisms and β-lactamase genes (bla). Live bacteria were not detected by selective culture. However, PCR investigations on food DNA extracts indicated that samples harbored the blaCTX-M-15 (53.3%), blaCMY-4 (20%), and blaVEB-4-like (6.7%) genes. Particularly worrisome was the presence of blaOXA-48-like carbapenemases (13.3%). The original pet food ingredients and/or the production processes were highly contaminated with bacteria carrying clinically relevant acquired bla genes. PMID:25092703

  7. The regioselective iodination of quinolines, quinolones, pyridones, pyridines and uracil.

    Science.gov (United States)

    Dutta, Uttam; Deb, Arghya; Lupton, David W; Maiti, Debabrata

    2015-12-28

    A radical based direct C-H iodination protocol for quinolines, quinolones, pyridones, pyridines, and uracil has been developed. The iodination occurs in a C3 selective manner for quinolines and quinolones. Pyridones and pyridines undergo C3 and C5 iodination, while dimethyl uracil undergoes C5 iodination. Scope of the method was demonstrated through the rapid synthesis of both electron rich as well as electron poor heteroaromatic iodides. The protocol was found to be scalable and general, while a mechanism has been proposed.

  8. High prevalence of extended-spectrum β-lactamase, plasmid-mediated AmpC, and carbapenemase genes in pet food.

    Science.gov (United States)

    Seiffert, Salome N; Carattoli, Alessandra; Tinguely, Regula; Lupo, Agnese; Perreten, Vincent; Endimiani, Andrea

    2014-10-01

    We evaluated the pet food contained in 30 packages as a potential origin of extended-spectrum cephalosporin-resistant Gram-negative organisms and β-lactamase genes (bla). Live bacteria were not detected by selective culture. However, PCR investigations on food DNA extracts indicated that samples harbored the blaCTX-M-15 (53.3%), blaCMY-4 (20%), and blaVEB-4-like (6.7%) genes. Particularly worrisome was the presence of blaOXA-48-like carbapenemases (13.3%). The original pet food ingredients and/or the production processes were highly contaminated with bacteria carrying clinically relevant acquired bla genes. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  9. Acute toxicity evaluation for quinolone antibiotics and their chlorination disinfection processes.

    Science.gov (United States)

    Li, Min; Wei, Dongbin; Du, Yuguo

    2014-09-01

    Acute toxicity of 21 quinolone antibiotics was monitored using photobacterium Vibrio fischeri assay. The minimum IC20 (inhibitory concentration for 20% luminescence elimination) was obtained at the least 18.86μmol/L for the tested quinolones. A quantitative structure-activity relationship model was established to investigate the possible mechanism for the acute toxicity. The critical physicochemical descriptors, describing σ and π atom electronegativity, implied that the electron transfer might occur between the quinolones and photobacterium V. fischeri. Although the quinolones exhibited limited acute toxicity to photobacterium, toxicity elevation was detected after their chlorination. Hence, chlorination disinfection treatment of quinolone-containing water should be of concerns.

  10. Novel genetic environment of the plasmid-mediated KPC-3 gene detected in Escherichia coli and Citrobacter freundii isolates from China.

    Science.gov (United States)

    Li, G; Wei, Q; Wang, Y; Du, X; Zhao, Y; Jiang, X

    2011-04-01

    The imipenem and meropenem-resistant strains Citrobacter freundii HS70 and Escherichia coli HS510 were isolated from patients in Shanghai, China. By isoelectric focusing, PCR amplification and sequencing, these strains were each found to produce four β-lactamases: TEM-1, KPC-3, SHV-7 and CTX-M-14. A conjugation experiment and plasmid restriction digestion revealed that the bla (KPC-3) gene was located on the same plasmid in both isolates. Bidirectional primer walking sequencing showed that the nucleotide sequence surrounding the 3.8 kb bla(KPC-3) contained a 671-bp insertion similar to that previously characterized in China. The insertion was located between the promoter and the coding region of the bla(KPC-3) gene. Susceptibility testing performed on recombinant strains carrying the bla(KPC-3) gene with or without the insertion revealed that minimum inhibitory concentrations of imipenem, meropenem, cefepime, and cefotaxime for E. coli EMU-KPC3 (without insertion) were four times higher than that of E. coli EKPC3 (with insertion). The 671 bp insertion reduced bla(KPC-3) expression significantly. Taken together, these results suggest that KPC-3-producing C. freundii and E. coli have begun to emerge in our hospital.

  11. Rapid evolution of fluoroquinolone-resistant Escherichia coli in Nigeria is temporally associated with fluoroquinolone use

    Science.gov (United States)

    2011-01-01

    Background Antibiotic resistance has necessitated fluoroquinolone use but little is known about the selective forces and resistance trajectory in malaria-endemic settings, where selection from the antimalarial chloroquine for fluoroquinolone-resistant bacteria has been proposed. Methods Antimicrobial resistance was studied in fecal Escherichia coli isolates in a Nigerian community. Quinolone-resistance determining regions of gyrA and parC were sequenced in nalidixic acid resistant strains and horizontally-transmitted quinolone-resistance genes were sought by PCR. Antimicrobial prescription practices were compared with antimicrobial resistance rates over a period spanning three decades. Results Before 2005, quinolone resistance was limited to low-level nalixidic acid resistance in fewer than 4% of E. coli isolates. In 2005, the proportion of isolates demonstrating low-level quinolone resistance due to elevated efflux increased and high-level quinolone resistance and resistance to the fluoroquinolones appeared. Fluoroquinolone resistance was attributable to single nucleotide polymorphisms in quinolone target genes gyrA and/or parC. By 2009, 35 (34.5%) of isolates were quinolone non-susceptible with nine carrying gyrA and parC SNPs and six bearing identical qnrS1 alleles. The antimalarial chloroquine was heavily used throughout the entire period but E. coli with quinolone-specific resistance mechanisms were only detected in the final half decade, immediately following the introduction of the fluoroquinolone antibacterial ciprofloxacin. Conclusions Fluoroquinolones, and not chloroquine, appear to be the selective force for fluoroquinolone-resistant fecal E. coli in this setting. Rapid evolution to resistance following fluoroquinolone introduction points the need to implement resistant containment strategies when new antibacterials are introduced into resource-poor settings with high infectious disease burdens. PMID:22060770

  12. Shifts in the Antibiotic Susceptibility, Serogroups, and Clonal Complexes of Neisseria meningitidis in Shanghai, China: A Time Trend Analysis of the Pre-Quinolone and Quinolone Eras.

    Directory of Open Access Journals (Sweden)

    Mingliang Chen

    2015-06-01

    Full Text Available Fluoroquinolones have been used broadly since the end of the 1980s and have been recommended for Neisseria meningitidis prophylaxis since 2005 in China. The aim of this study was to determine whether and how N. meningitidis antimicrobial susceptibility, serogroup prevalence, and clonal complex (CC prevalence shifted in association with the introduction and expanding use of quinolones in Shanghai, a region with a traditionally high incidence of invasive disease due to N. meningitidis.A total of 374 N. meningitidis isolates collected by the Shanghai Municipal Center for Disease Control and Prevention between 1965 and 2013 were studied. Shifts in the serogroups and CCs were observed, from predominantly serogroup A CC5 (84% in 1965-1973 to serogroup A CC1 (58% in 1974-1985, then to serogroup C or B CC4821 (62% in 2005-2013. The rates of ciprofloxacin nonsusceptibility in N. meningitidis disease isolates increased from 0% in 1965-1985 to 84% (31/37 in 2005-2013 (p < 0.001. Among the ciprofloxacin-nonsusceptible isolates, 87% (27/31 were assigned to either CC4821 (n = 20 or CC5 (n = 7. The two predominant ciprofloxacin-resistant clones were designated ChinaCC4821-R1-C/B and ChinaCC5-R14-A. The ChinaCC4821-R1-C/B clone acquired ciprofloxacin resistance by a point mutation, and was present in 52% (16/31 of the ciprofloxacin-nonsusceptible disease isolates. The ChinaCC5-R14-A clone acquired ciprofloxacin resistance by horizontal gene transfer, and was found in 23% (7/31 of the ciprofloxacin-nonsusceptible disease isolates. The ciprofloxacin nonsusceptibility rate was 47% (7/15 among isolates from asymptomatic carriers, and nonsusceptibility was associated with diverse multi-locus sequence typing profiles and pulsed-field gel electrophoresis patterns. As detected after 2005, ciprofloxacin-nonsusceptible strains were shared between some of the patients and their close contacts. A limitation of this study is that isolates from 1986-2004 were not available

  13. Prevalence and characterization of plasmid-mediated blaESBL with their genetic environment in Escherichia coli and Klebsiella pneumoniae in patients with pneumonia

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-rong; CHEN Ji-chao; KANG Yu; JIANG Ning; AN Shu-chang; GAO Zhan-cheng

    2012-01-01

    Background The extended spectrum β-lactamase (ESBL)-producing Escherichia coli (E.coli) and Klebsiella pneumoniae (K.pneumoniae) are the major pathogens causing pneumonia and have a significant impact on the clinical course.Limited data exist on molecular characterization of ESBL-producing E.coli and K.pneumoniae that cause pneumonia.The aim of this study was to investigate the comprehensive multilevel characteristics of E.coli and K.pneumoniae causing pneumonia in China for the first time.Methods E.coli (17) and K.pneumoniae (21) isolates responsible for pneumonia were isolated from 1270 specimens collected in a prospective multi-center study in eight teaching hospitals in China from June to December in 2007.The susceptibilities,ESBL confirmation,sequence typing,blaCTX-M and blaSHV genes,their genetic environment and plasmid Inc/rep types were determined.Results Sixteen E.coli (94.1%) and eleven K.pneumoniae (52.4%) isolates were ESBL producers.About 77.8% and 66.7% of them were resistance to ciprofloxacin and levofloxacin,and 100% were susceptible to imipenem.The most prevalent ESBL gene was CTX-M-14,followed by SHV-2,CTX-M-15,CTX-M-3,CTX-M-65,SHV-12,SHV-26 and SHV-28.SHV-1 and SHV-11 were also detected and coexisted with blaCTX-Ms in five strains,and three strains contained only SHV-1.All CTX-M-14 were detected ISEcp1 upstream and nine were found IS903 downstream and the majority of them (64.3%) were carried by IncF plasmids.All blasHv were flanked by recFand deoR,located on IncF,IncN,IncX and IncH plasmids.Two SHV-2,one SHV-1 and the only SHV-28 were further preceded by IS26.Genes lacYand lacZwere detected at further upstream of two blaSHv-1.The K.pneumoniae carrying SHV-28 was susceptible to β-lactams,and no mutations or deletions in gene or promoter sequences were identified to account for susceptibility.Multilocus sequence typing experiments showed the ESBL-producing strains were genetically diverse.Conclusio