Variants of β-lactamase KPC-2 that are resistant to inhibition by avibactam.

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Papp-Wallace, Krisztina M; Winkler, Marisa L; Taracila, Magdalena A; Bonomo, Robert A

2015-07-01

KPC-2 is the most prevalent class A carbapenemase in the world. Previously, KPC-2 was shown to hydrolyze the β-lactamase inhibitors clavulanic acid, sulbactam, and tazobactam. In addition, substitutions at amino acid position R220 in the KPC-2 β-lactamase increased resistance to clavulanic acid. A novel bridged diazabicyclooctane (DBO) non-β-lactam β-lactamase inhibitor, avibactam, was shown to inactivate the KPC-2 β-lactamase. To better understand the mechanistic basis for inhibition of KPC-2 by avibactam, we tested the potency of ampicillin-avibactam and ceftazidime-avibactam against engineered variants of the KPC-2 β-lactamase that possessed single amino acid substitutions at important sites (i.e., Ambler positions 69, 130, 234, 220, and 276) that were previously shown to confer inhibitor resistance in TEM and SHV β-lactamases. To this end, we performed susceptibility testing, biochemical assays, and molecular modeling. Escherichia coli DH10B carrying KPC-2 β-lactamase variants with the substitutions S130G, K234R, and R220M demonstrated elevated MICs for only the ampicillin-avibactam combinations (e.g., 512, 64, and 32 mg/liter, respectively, versus the MICs for wild-type KPC-2 at 2 to 8 mg/liter). Steady-state kinetics revealed that the S130G variant of KPC-2 resisted inactivation by avibactam; the k2/K ratio was significantly lowered 4 logs for the S130G variant from the ratio for the wild-type enzyme (21,580 M(-1) s(-1) to 1.2 M(-1) s(-1)). Molecular modeling and molecular dynamics simulations suggested that the mobility of K73 and its ability to activate S70 (i.e., function as a general base) may be impaired in the S130G variant of KPC-2, thereby explaining the slowed acylation. Moreover, we also advance the idea that the protonation of the sulfate nitrogen of avibactam may be slowed in the S130G variant, as S130 is the likely proton donor and another residue, possibly K234, must compensate. Our findings show that residues S130 as well as K234 and R

Crystal Structures of KPC-2[beta]-Lactamase in Complex with 3-Nitrophenyl Boronic Acid and the Penam Sulfone PSR-3-226

Energy Technology Data Exchange (ETDEWEB)

Ke, Wei; Bethel, Christopher R.; Papp-Wallace, Krisztina M.; Pagadala, Sundar Ram Reddy; Nottingham, Micheal; Fernandez, Daniel; Buynak, John D.; Bonomo, Robert A.; van den Akker, Focco (Case Western); (Stokes); (SMU)

2012-08-01

Class A carbapenemases are a major threat to the potency of carbapenem antibiotics. A widespread carbapenemase, KPC-2, is not easily inhibited by {beta}-lactamase inhibitors (i.e., clavulanic acid, sulbactam, and tazobactam). To explore different mechanisms of inhibition of KPC-2, we determined the crystal structures of KPC-2 with two {beta}-lactamase inhibitors that follow different inactivation pathways and kinetics. The first complex is that of a small boronic acid compound, 3-nitrophenyl boronic acid (3-NPBA), bound to KPC-2 with 1.62-{angstrom} resolution. 3-NPBA demonstrated a Km value of 1.0 {+-} 0.1 {micro}M (mean {+-} standard error) for KPC-2 and blocks the active site by making a reversible covalent interaction with the catalytic S70 residue. The two boron hydroxyl atoms of 3-NPBA are positioned in the oxyanion hole and the deacylation water pocket, respectively. In addition, the aromatic ring of 3-NPBA provides an edge-to-face interaction with W105 in the active site. The structure of KPC-2 with the penam sulfone PSR-3-226 was determined at 1.26-{angstrom} resolution. PSR-3-226 displayed a K{sub m} value of 3.8 {+-} 0.4 {micro}M for KPC-2, and the inactivation rate constant (kinact) was 0.034 {+-} 0.003 s{sup -1}. When covalently bound to S70, PSR-3-226 forms a trans-enamine intermediate in the KPC-2 active site. The predominant active site interactions are generated via the carbonyl oxygen, which resides in the oxyanion hole, and the carboxyl moiety of PSR-3-226, which interacts with N132, N170, and E166. 3-NPBA and PSR-3-226 are the first {beta}-lactamase inhibitors to be trapped as an acyl-enzyme complex with KPC-2. The structural and inhibitory insights gained here could aid in the design of potent KPC-2 inhibitors.

Multifocal diffusion of KPC-3-producing ST512 Klebsiella pneumoniae in Italy

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Aurora Piazza

2012-03-01

Full Text Available Introduction. The dissemination of carbapenemase-producing Klebsiella pneumoniae strains is an increasing problem worldwide. KPC ß-lactamases are Ambler class A enzymes mostly plasmid-encoded; their global spread represents a threat to clinical patients care and public health. Multi locus sequence type (ST258 is currently the most spread K. pneumoniae clone associated with KPC enzymes. Here we report the first identification and multifocal spread of KPC-3 producing K. pneumoniae clinical strains belonging to ST512 in Italy. Materials and Methods. Fifty six carbapenem-resistant K. pneumoniae isolates were collected from 7 Italian hospitals during the period June 2009-May 2011. Isolates were obtained from different wards (spinal unit, medicine, hematology, etc. and biological samples (mostly rectal swabs, urine and blood. Species identification and antimicrobial susceptibilities were obtained by NBC46/NM40 Microscan panels (Siemens. MICs values were interpreted according to EUCAST 2011 breakpoints. Modified Hodge test and combined disk test with phenyl-boronic acid (BOR and EDTA were performed.The presence of blaKPC genes were confirmed by PCR and sequencing. A complete characterization of the produced ß-lactamases (BLs was obtained by IEF followed by PCR experiments using primers specific for the detection of blaCTX-M-, blaTEM- and blaSHV type genes. PFGE and multilocus sequence typing (MLST were both used to investigate clonal isolates relatedness. Results. All 56 isolates resulted positive for the presence of KPC-type carbapenemases by both phenotypical and molecular analysis. Fifteen isolates, chosen as representative, were further investigated. Ten out of 15 isolates harboring the blaKPC-2 gene clustered with the known ST258, while the remaining 5/10 belonged to the newly described ST512 and harbored the blaKPC-3 gene. ST512 isolates, from 3/7 hospitals, were collected from rectal swabs (40%, blood (20%, endotracheal aspirate (20% and

WCK 4234, a novel diazabicyclooctane potentiating carbapenems against Enterobacteriaceae, Pseudomonas and Acinetobacter with class A, C and D β-lactamases.

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Mushtaq, Shazad; Vickers, Anna; Woodford, Neil; Livermore, David M

2017-06-01

Several diazabicyclooctanes (DBOs) are under development as inhibitors of class A and C β-lactamases. Inhibition of OXA (class D) carbapenemases is variable, with those of Acinetobacter spp. remaining notably resistant. We describe a novel DBO, WCK 4234 (Wockhardt), with distinctive activity against OXA carbapenemases. MICs of imipenem and meropenem were determined by CLSI agar dilution with WCK 4234 added at 4 or 8 mg/L. Test organisms were clinical Enterobacteriaceae, Acinetobacter baumannii and Pseudomonas aeruginosa with carbapenemases or carbapenem resistance via porin loss plus AmpC or ESBL activity. AmpC mutants were also tested. WCK 4234, which lacked direct antibacterial activity, strongly potentiated imipenem and meropenem against Enterobacteriaceae with OXA-48/OXA-181 or KPC enzymes, or with combinations of impermeability and AmpC or ESBL activity, with MICs reduced to ≤2 mg/L in almost all cases. Carbapenems likewise were potentiated against P. aeruginosa ( n  =   2) with OXA-181 enzyme, with MICs reduced from 64-128 to 2-8 mg/L and against A. baumannii with OXA carbapenemases, particularly OXA-23 or hyperproduced OXA-51, with MICs reduced to ≤2 mg/L for 9/10 acinetobacters with OXA-23 enzyme. Carbapenems were not potentiated against Enterobacteriaceae or non-fermenters with metallo-β-lactamases. WCK 4234 distinctively overcame resistance mediated by OXA-type carbapenemases, including those of A. baumannii . It behaved similarly to other DBOs against strains with KPC carbapenemases or combinations of impermeability and ESBL or AmpC activity. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Carbapenem-Nonsusceptible Enterobacteriaceae in Taiwan

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Wang, Jann-Tay; Wu, Un-In; Lauderdale, Tsai-Ling Yang; Chen, Mei-Chen; Li, Shu-Ying; Hsu, Le-Yin; Chang, Shan-Chwen

2015-01-01

A total of 1135 carbapenem-resistant (nonsusceptible) Enterobacteriaceae (CRE) isolates were recovered between November 2010 and July 2012 (517 from 2010-2011 and 618 from 2012) from 4 hospitals in Taiwan. Carbapenemase-producing Enterobacteriaceae (CPE) comprised 5.0% (57 isolates), including 17 KPC-2 (16 Klebsiella pneumoniae and 1 Escherichia coli), 1 NDM-1 (K. oxytoca), 37 IMP-8 (26 Enterobacter cloacae, 4 Citrobacter freundii, 4 Raoultella planticola, 1 K. pneumoniae, 1 E. coli and 1 K. oxytoca), and 2 VIM-1 (1 E. cloacae, 1 E. coli). The KPC-2-positive K. pneumoniae were highly clonal even in isolates from different hospitals, and all were ST11. IMP-8 positive E. cloacae from the same hospitals showed higher similarity in PFGE pattern than those from different hospitals. A total of 518 CRE isolates (45.6%) were positive for bla ESBL, while 704 (62.0%) isolates were bla AmpC-positive, 382 (33.6% overall) of which carried both bla ESBL and bla AmpC. CTX-M (414, 80.0%) was the most common bla ESBL, while DHA (497, 70.6%) and CMY (157, 22.3%) were the most common bla AmpC. Co-carriage of bla ESBL and bla AmpC was detected in 31 (54.4%) and 15 (26.3%) of the 57 CPE, respectively. KPC-2 was the most common carbapenemase detected in K. pneumoniae (2.8%), while IMP-8 was the most common in E. cloacae (9.7%). All KPC-2-positive CRE were resistant to all three tested carbapenems. However, fourteen of the 37 IMP-8-positive CRE were susceptible to both imipenem and meropenem in vitro. Intra- and inter-hospital spread of KPC-2-producing K. pneumoniae and IMP-8-producing E. cloacae likely occurred. Although the prevalence of CPE is still low, careful monitoring is urgently needed. Non-susceptibility to ertapenem might need to be considered as one criterion of definition for CRE in areas where IMP type carbapenemase is prevalent. PMID:25794144

Isolation of Enterobacter aerogenes carrying blaTEM-1 and blaKPC-3 genes recovered from a hospital Intensive Care Unit.

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Pulcrano, Giovanna; Pignanelli, Salvatore; Vollaro, Adriana; Esposito, Matilde; Iula, Vita Dora; Roscetto, Emanuela; Soriano, Amata Amy; Catania, Maria Rosaria

2016-06-01

Enterobacter aerogenes has recently emerged as an important hospital pathogen. In this study, we showed the emergence of E. aerogenes isolates carrying the blaKPC gene in patients colonized by carbapenem-resistant Klebsiella pneumoniae strains. Two multiresistant E. aerogenes isolates were recovered from bronchial aspirates of two patients hospitalized in the Intensive Care Unit at the "Santa Maria della Scaletta" Hospital, Imola. The antimicrobial susceptibility test showed the high resistance to carbapenems and double-disk synergy test confirmed the phenotype of KPC and AmpC production. Other investigation revealed that ESBL and blaKPC genes were carried on the conjugative pKpQIL plasmid. This is a relevant report in Italy that describes a nosocomial infection due to the production of KPC beta-lactamases by an E. aerogenes isolate in patients previously colonized by K. pneumoniae carbapenem-resistant. In conclusion, it's necessary a continuous monitoring of multidrug-resistant strains for the detection of any KPC-producing bacteria that could expand the circulation of carbapenem-resistant pathogens. © 2016 APMIS. Published by John Wiley & Sons Ltd.

Occurrence of Enterobacter hormaechei carrying blaNDM-1 and blaKPC-2 in China.

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Yang, Biwei; Feng, Yu; McNally, Alan; Zong, Zhiyong

2018-02-01

Three carbapenem-resistant clinical isolates of the Enterobacter cloacae complex (ECC) were recovered from different patients in a hospital. All 3 isolates carried 2 carbapenemase genes bla KPC-2 and bla NDM-1 . A study was performed to characterize their relatedness and to investigate possible links among the patients. Whole genome sequencing revealed that the isolates were Enterobacter hormaechei and belonged to ST177 of the ECC. There were 19-142 single nucleotide polymorphisms (SNPs) between the isolates, suggesting that the isolates were likely from a central reservoir, which might have existed for some time. bla KPC-2 and bla NDM-1 were carried on 2 different IncF-type plasmids in the isolates. The 3 bla NDM-1 -carrying plasmids were almost identical and were self-transmissible, while the bla KPC-2 -carrying plasmids were only transmissible in the presence of the bla NDM-1 -carrying plasmid. The source of and direct links among them were not identified, suggesting a hospital transmission of a common multidrug resistant strain. Copyright © 2017 Elsevier Inc. All rights reserved.

Klebsiella pneumoniae KPC: first isolations in Italy

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Carla Fontana

2009-12-01

Full Text Available Klebsiella pneumoniae carbapenemase (KPC was detected in two isolates of carbapenem-resistant K. pneumoniae in an italian teaching hospital. This is the first report of a KPC-producing isolates in our country. The first strain was isolated from a urine sample collected from a indwelling urinary catheter in a ICU-patient with subdural haematoma, while the second was from the culture of the central venous catheter (CVC in a patient affected by Crohn’s disease admitted in gastroenterology ward. Both were resistant to all ß-lactams, susceptible to imipenem and meropenem and resistant to ertapenem.They were resistant to other classes of non-ß-lactams antibiotics such as quinolones, aminoglycosides (with the exception of amikacin, trimethoprim-sulfamethoxazole (TMP-SMX as well as to nitrofurantoin.The isolates were not associated with travel abroad.They were found to contain the plasmid encoded carbapenemase gene blaKPC and were also positive to the Hodge’s test.The detection of KPC-producing bacteria has important implications in infection control and public health. The K. pneumoniae carbapenemase (KPC belong to class A ß-lactamases of the functional group 2f. Reported for the first time in U.S. in 2001, these agents were subsequently identified in Europe. KPC strains are typically resistant to penicillins, extended-spectrum cephalosporin and aztreonam and present a peculiar behavior against carbapenems in that MIC is close to the susceptibility value or is borderline (except for ertapenem.This pattern is often associated with resistance to quinolones.The information is conveyed by the resistance plasmids, thus explaining their diffusion and implication in outbreaks of KPC. Despite this, to date there are few reports concerning the isolation of this phenotype in Italy.The purpose of this paper is to present two clinical cases related to the isolation of KPC in our hospital. The KPC-producing strains have been respectively isolated: the first

The emergence of carbapenem-resistant Klebsiella pneumoniae isolates producing OXA-48 and NDM in the Southern (Asir) province, Saudi Arabia.

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Al-Zahrani, Ibrahim A; Alsiri, Bander A

2018-01-01

To identify the prevalence of carbapenem-resistant Klebsiella pneumoniae (CRKP) and the most common types of cabapenemases among CRKP in the Southern (Asir) province hospitals, Saudi Arabia. Methods: The cross-sectional study was conducted between late April and September in 2015. A total of 54 Klebsiella pneumoniae (K. pneumoniae) isolates with reduced sensitivity to carbapenems were obtained from various clinical specimens of the 2 largest hospitals in the Southern province. Minimum inhibitory concentrations (MICs) of carbapenems were confirmed using E-test. Molecular detection of the most common carbapenemase genes (blaIMP, bla-carbapenem-hydrolyzing oxacillinase [OXA-48], blaVIM, bla-New Delhi metallo-ß-lactamas [NDM], and blaKPC) was performed using multiplex-polymerase chain reaction. Results: The current study found that increasing age and intensive care unit admission were associated with CRKP isolation. The major type of carbapenemases was OXA-48 with 81.5% (n=44) and it seems to reach an endemic level. New Delhi metallo-ß-lactamas (NDM) was the second most frequent carbapenemase by 7.4% (n=4) of isolates while Verona integron-encoded metallo-ß-lactamase (VIM) was reported only in one isolate. Conclusion: Saudi Arabia receives large numbers of visitors and migrant workers from OXA-48 and NDM endemic countries such as Turkey, India, and Pakistan every year.

The emergence of carbapenem-resistant Klebsiella pneumoniae isolates producing OXA-48 and NDM in the Southern (Asir province, Saudi Arabia

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Ibrahim A. Al-Zahrani

2018-01-01

Full Text Available Objectives: To identify the prevalence of carbapenem-resistant Klebsiella pneumoniae (CRKP and the most common types of cabapenemases among CRKP in the Southern (Asir province hospitals, Saudi Arabia. Methods: The cross-sectional study was conducted between late April and September in 2015. A total of 54 Klebsiella pneumoniae (K. pneumoniae isolates with reduced sensitivity to carbapenems were obtained from various clinical specimens of the 2 largest hospitals in the Southern province. Minimum inhibitory concentrations (MICs of carbapenems were confirmed using E-test. Molecular detection of the most common carbapenemase genes (blaIMP, bla-carbapenem-hydrolyzing oxacillinase [OXA-48], blaVIM, bla-New Delhi metallo-ß-lactamas [NDM], and blaKPC was performed using multiplex-polymerase chain reaction. Results: The current study found that increasing age and intensive care unit admission were associated with CRKP isolation. The major type of carbapenemases was OXA-48 with 81.5% (n=44 and it seems to reach an endemic level. New Delhi metallo-ß-lactamas (NDM was the second most frequent carbapenemase by 7.4% (n=4 of isolates while Verona integron-encoded metallo-ß-lactamase (VIM was reported only in one isolate. Conclusion: Saudi Arabia receives large numbers of visitors and migrant workers from OXA-48 and NDM endemic countries such as Turkey, India, and Pakistan every year.

Synthetic polyester-hydrolyzing enzymes from thermophilic actinomycetes.

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Wei, Ren; Oeser, Thorsten; Zimmermann, Wolfgang

2014-01-01

Thermophilic actinomycetes produce enzymes capable of hydrolyzing synthetic polyesters such as polyethylene terephthalate (PET). In addition to carboxylesterases, which have hydrolytic activity predominantly against PET oligomers, esterases related to cutinases also hydrolyze synthetic polymers. The production of these enzymes by actinomycetes as well as their recombinant expression in heterologous hosts is described and their catalytic activity against polyester substrates is compared. Assays to analyze the enzymatic hydrolysis of synthetic polyesters are evaluated, and a kinetic model describing the enzymatic heterogeneous hydrolysis process is discussed. Structure-function and structure-stability relationships of actinomycete polyester hydrolases are compared based on molecular dynamics simulations and recently solved protein structures. In addition, recent progress in enhancing their activity and thermal stability by random or site-directed mutagenesis is presented. © 2014 Elsevier Inc. All rights reserved.

Yield of ethanol from enzyme-hydrolyzed yam (Dioscorea rotundata ...

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Fresh whole yam tubers and cocoyam corms were separately processed into flours by washing, peeling, blanching, slicing,drying and milling. The flours were enzyme-hydrolyzed by mixing 500g of flour with 2Lof water followed by treatment with a combination of bacterial alpha amylase, limit dextrinase and fungal alpha ...

The spread of KPC-producing Enterobacteriaceae in Spain: WGS analysis of the emerging high-risk clones of Klebsiella pneumoniae ST11/KPC-2, ST101/KPC-2 and ST512/KPC-3.

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Oteo, Jesús; Pérez-Vázquez, María; Bautista, Verónica; Ortega, Adriana; Zamarrón, Pilar; Saez, David; Fernández-Romero, Sara; Lara, Noelia; Ramiro, Raquel; Aracil, Belén; Campos, José

2016-12-01

We analysed the microbiological traits and population structure of KPC-producing Enterobacteriaceae isolates collected in Spain between 2012 and 2014. We also performed a comparative WGS analysis of the three major KPC-producing Klebsiella pneumoniae clones detected. Carbapenemase and ESBL genes were sequenced. The Institut Pasteur MLST scheme was used. WGS data were used to construct phylogenetic trees, to identify the determinants of resistance and to de novo assemble the genome of one representative isolate of each of the three major K. pneumoniae clones. Of the 2443 carbapenemase-producing Enterobacteriaceae isolates identified during the study period, 111 (4.5%) produced KPC. Of these, 81 (73.0%) were K. pneumoniae and 13 (11.7%) were Enterobacter cloacae. Three major epidemic clones of K. pneumoniae were identified: ST11/KPC-2, ST101/KPC-2 and ST512/KPC-3. ST11/KPC-2 differed from ST101/KPC-2 and ST512/KPC-3 by 27 819 and 6924 SNPs, respectively. ST101/KPC-2 differed from ST512/KPC-3 by 28 345 SNPs. Nine acquired resistance genes were found in ST11/KPC-2, 11 in ST512/KPC-3 and 13 in ST101/KPC-2. ST101/KPC-2 had the highest number of virulence genes (20). An 11 bp deletion at the end of the mgrB sequence was the cause of colistin resistance in ST512/KPC-3. KPC-producing Enterobacteriaceae are increasing in Spain. Most KPC-producing K. pneumoniae isolates belonged to only five clones: ST11 and ST512 caused interregional spread, ST101 caused regional spread and ST1961 and ST678 produced independent hospital outbreaks. ST101/KPC-2 had the highest number of resistance and virulence genes. ST101/KPC-2 and ST512/KPC-3 were recently implicated in the spread of KPC in Italy. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Anti-Restriction Protein, KlcAHS, Promotes Dissemination of Carbapenem Resistance

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Xiaofei Jiang

2017-05-01

Full Text Available Carbapenemase-producing Klebsiella pneumoniae (KPC has emerged and spread throughout the world. A retrospective analysis was performed on carbapenem-resistant K. pneumoniae isolated at our teaching hospital during the period 2009–2010, when the initial outbreak occurred. To determine the mechanism(s that underlies the increased infectivity exhibited by KPC, Multilocus Sequence Typing (MLST was conducted. A series of plasmids was also extracted, sequenced and analyzed. Concurrently, the complete sequences of blaKPC−2-harboring plasmids deposited in GenBank were summarized and aligned. The blaKPC−2 and KlcAHS genes in the carbapenem-resistant K. pneumoniae isolates were examined. E. coli strains, carrying different Type I Restriction and Modification (RM systems, were selected to study the interaction between RM systems, anti-RM systems and horizontal gene transfer (HGT. The ST11 clone predominated among 102 carbapenem-resistant K. pneumoniae isolates, all harbored the blaKPC−2 gene; 98% contained the KlcAHS gene. KlcAHS was one of the core genes in the backbone region of most blaKPC−2 carrying plasmids. Type I RM systems in the host bacteria reduced the rate of pHS10842 plasmid transformation by 30- to 40-fold. Presence of the anti-restriction protein, KlcAHS, on the other hand, increased transformation efficiency by 3- to 6-fold. These results indicate that RM systems can significantly restrict HGT. In contrast, KlcAHS can disrupt the RM systems and promote HGT by transformation. These findings suggest that the anti-restriction protein, KlcAHS, represents a novel mechanism that facilitates the increased transfer of blaKPC-2 and KlcAHS-carrying plasmids among K. pneumoniae strains.

Clonality, outer-membrane proteins profile and efflux pump in KPC- producing Enterobacter sp. in Brazil.

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Rosa, Juliana Ferraz; Rizek, Camila; Marchi, Ana Paula; Guimaraes, Thais; Miranda, Lourdes; Carrilho, Claudia; Levin, Anna S; Costa, Silvia F

2017-03-17

Carbapenems resistance in Enterobacter spp. has increased in the last decade, few studies, however, described the mechanisms of resistance in this bacterium. This study evaluated clonality and mechanisms of carbapenems resistance in clinical isolates of Enterobacter spp. identified in three hospitals in Brazil (Hospital A, B and C) over 7-year. Antibiotics sensitivity, pulsed-field gel electrophoresis (PFGE), PCR for carbapenemase and efflux pump genes were performed for all carbapenems-resistant isolates. Outer-membrane protein (OMP) was evaluated based on PFGE profile. A total of 130 isolates of Enterobacter spp were analyzed, 44/105 (41, 9%) E. aerogenes and 8/25 (32,0%) E. cloacae were resistant to carbapenems. All isolates were susceptible to fosfomycin, polymyxin B and tigecycline. KPC was present in 88.6% of E. aerogenes and in all E. cloacae resistant to carbapenems. The carbapenems-resistant E. aerogenes identified in hospital A belonged to six clones, however, a predominant clone was identified in this hospital over the study period. There is a predominant clone in Hospital B and Hospital C as well. The mechanisms of resistance to carbapenems differ among subtypes. Most of the isolates co-harbored blaKPC, blaTEM and /or blaCTX associated with decreased or lost of 35-36KDa and or 39 KDa OMP. The efflux pump AcrAB-TolC gene was only identified in carbapenems-resistant E. cloacae. There was a predominant clone in each hospital suggesting that cross-transmission of carbapenems-resistant Enterobacter spp. was frequent. The isolates presented multiple mechanisms of resistance to carbapenems including OMP alteration.

Multicenter Clinical and Molecular Epidemiological Analysis of Bacteremia Due to Carbapenem-Resistant Enterobacteriaceae (CRE) in the CRE Epicenter of the United States

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Chen, Liang; Patel, Gopi; Gomez-Simmonds, Angela; Weston, Gregory; Kim, Angela C.; Seo, Susan K.; Rosenthal, Marnie E.; Sperber, Steven J.; Jenkins, Stephen G.; Hamula, Camille L.; Uhlemann, Anne-Catrin; Levi, Michael H.; Fries, Bettina C.; Juretschko, Stefan; Rojtman, Albert D.; Hong, Tao; Mathema, Barun; Jacobs, Michael R.; Walsh, Thomas J.; Bonomo, Robert A.; Kreiswirth, Barry N.

2017-01-01

ABSTRACT Although the New York/New Jersey (NY/NJ) area is an epicenter for carbapenem-resistant Enterobacteriaceae (CRE), there are few multicenter studies of CRE from this region. We characterized patients with CRE bacteremia in 2013 at eight NY/NJ medical centers and determined the prevalence of carbapenem resistance among Enterobacteriaceae bloodstream isolates and CRE resistance mechanisms, genetic backgrounds, capsular types (cps), and antimicrobial susceptibilities. Of 121 patients with CRE bacteremia, 50% had cancer or had undergone transplantation. The prevalences of carbapenem resistance among Klebsiella pneumoniae, Enterobacter spp., and Escherichia coli bacteremias were 9.7%, 2.2%, and 0.1%, respectively. Ninety percent of CRE were K. pneumoniae and 92% produced K. pneumoniae carbapenemase (KPC-3, 48%; KPC-2, 44%). Two CRE produced NDM-1 and OXA-48 carbapenemases. Sequence type 258 (ST258) predominated among KPC-producing K. pneumoniae (KPC-Kp). The wzi154 allele, corresponding to cps-2, was present in 93% of KPC-3-Kp, whereas KPC-2-Kp had greater cps diversity. Ninety-nine percent of CRE were ceftazidime-avibactam (CAZ-AVI)-susceptible, although 42% of KPC-3-Kp had an CAZ-AVI MIC of ≥4/4 μg/ml. There was a median of 47 h from bacteremia onset until active antimicrobial therapy, 38% of patients had septic shock, and 49% died within 30 days. KPC-3-Kp bacteremia (adjusted odds ratio [aOR], 2.58; P = 0.045), cancer (aOR, 3.61, P = 0.01), and bacteremia onset in the intensive care unit (aOR, 3.79; P = 0.03) were independently associated with mortality. Active empirical therapy and combination therapy were not associated with survival. Despite a decade of experience with CRE, patients with CRE bacteremia have protracted delays in appropriate therapies and high mortality rates, highlighting the need for rapid diagnostics and evaluation of new therapeutics. PMID:28167547

Genetic characterization of blaNDM-harboring plasmids in carbapenem-resistant Escherichia coli from Myanmar.

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Yo Sugawara

Full Text Available The bacterial enzyme New Delhi metallo-β-lactamase hydrolyzes almost all β-lactam antibiotics, including carbapenems, which are drugs of last resort for severe bacterial infections. The spread of carbapenem-resistant Enterobacteriaceae that carry the New Delhi metallo-β-lactamase gene, blaNDM, poses a serious threat to public health. In this study, we genetically characterized eight carbapenem-resistant Escherichia coli isolates from a tertiary care hospital in Yangon, Myanmar. The eight isolates belonged to five multilocus-sequence types and harbored multiple antimicrobial-resistance genes, resulting in resistance against nearly all of the antimicrobial agents tested, except colistin and fosfomycin. Nine plasmids harboring blaNDM genes were identified from these isolates. Multiple blaNDM genes were found in the distinct Inc-replicon types of the following plasmids: an IncA/C2 plasmid harboring blaNDM-1 (n = 1, IncX3 plasmids harboring blaNDM-4 (n = 2 or blaNDM-7 (n = 1, IncFII plasmids harboring blaNDM-4 (n = 1 or blaNDM-5 (n = 3, and a multireplicon F plasmid harboring blaNDM-5 (n = 1. Comparative analysis highlighted the diversity of the blaNDM-harboring plasmids and their distinct characteristics, which depended on plasmid replicon types. The results indicate circulation of phylogenetically distinct strains of carbapenem-resistant E. coli with various plasmids harboring blaNDM genes in the hospital.

Abundance of carbapenemase genes (blaKPC, blaNDM and blaOXA-48) in wastewater effluents from Tunisian hospitals.

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Nasri, Emna; Subirats, Jessica; Sànchez-Melsió, Alexandre; Mansour, Hedi Ben; Borrego, Carles M; Balcázar, José Luis

2017-10-01

Carbapenems are β-lactam antibiotics with a broad spectrum of activity and are usually considered the last resort for the treatment of severe infections caused by multidrug-resistant pathogens. The clinically most significant carbapenemases are KPC, NDM, and OXA-48-like enzymes, whose genes have been increasingly reported worldwide in members of the family Enterobacteriaceae. In this study, we quantified the abundance of these genes in wastewater effluents from different Tunisian hospitals. The bla NDM and bla OXA-48 -like genes were detected at similar concentrations in all hospital wastewater effluents. In contrast, the bla KPC gene was detected at lower concentration than other genes and it was only detected in three of the seven effluents analyzed. To the best of our knowledge, this study quantified for the first time the abundance of bla KPC , bla NDM , and bla OXA-48 -like genes in wastewater effluents from Tunisian hospitals, highlighting the widespread distribution of these carbapenemase genes. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Complex Epidemiology of Carbapenem-Resistant Enterobacter Infections: A Multicenter Descriptive Analysis.

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Lazarovitch, Tsilia; Amity, Keren; Coyle, Joseph R; Ackerman, Benjamin; Tal-Jasper, Ruthy; Ofer-Friedman, Hadas; Hayakawa, Kayoko; Bogan, Christopher; Lephart, Paul R; Kaplansky, Tamir; Maskit, Moran; Azouri, Tal; Zaidenstein, Ronit; Perez, Federico; Bonomo, Robert A; Kaye, Keith S; Marchaim, Dror

2015-11-01

The pandemic of carbapenem-resistant Enterobacteriaceae (CRE) was primarily due to clonal spread of bla KPC producing Klebsiella pneumoniae. Thus, thoroughly studied CRE cohorts have consisted mostly of K. pneumoniae. To conduct an extensive epidemiologic analysis of carbapenem-resistant Enterobacter spp. (CREn) from 2 endemic and geographically distinct centers. CREn were investigated at an Israeli center (Assaf Harofeh Medical Center, January 2007 to July 2012) and at a US center (Detroit Medical Center, September 2008 to September 2009). bla KPC genes were queried by polymerase chain reaction. Repetitive extragenic palindromic polymerase chain reaction and pulsed-field gel electrophoresis were used to determine genetic relatedness. In this analysis, 68 unique patients with CREn were enrolled. Sixteen isolates (24%) were from wounds, and 33 (48%) represented colonization only. All isolates exhibited a positive Modified Hodge Test, but only 93% (27 of 29) contained bla KPC. Forty-three isolates (63%) were from elderly adults, and 5 (7.4%) were from neonates. Twenty-seven patients died in hospital (40.3% of infected patients). Enterobacter strains consisted of 4 separate clones from Assaf Harofeh Medical Center and of 4 distinct clones from Detroit Medical Center. In this study conducted at 2 distinct CRE endemic regions, there were unique epidemiologic features to CREn: (i) polyclonality, (ii) neonates accounting for more than 7% of cohort, and (iii) high rate of colonization (almost one-half of all cases represented colonization). Since false-positive Modified Hodge Tests in Enterobacter spp. are common, close monitoring of carbapenem resistance mechanisms (particularly carbapenemase production) among Enterobacter spp. is important.

Klebsiella pneumoniae Carbapenemase-2 (KPC-2), Substitutions at Ambler Position Asp179, and Resistance to Ceftazidime-Avibactam: Unique Antibiotic-Resistant Phenotypes Emerge from β-Lactamase Protein Engineering.

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Barnes, Melissa D; Winkler, Marisa L; Taracila, Magdalena A; Page, Malcolm G; Desarbre, Eric; Kreiswirth, Barry N; Shields, Ryan K; Nguyen, Minh-Hong; Clancy, Cornelius; Spellberg, Brad; Papp-Wallace, Krisztina M; Bonomo, Robert A

2017-10-31

mechanism of resistance is the breakdown of β-lactam antibiotics by β-lactamase enzymes. KPC-2 is a β-lactamase that inactivates carbapenems and β-lactamase inhibitors (e.g., clavulanate) and is prevalent around the world, including in the United States. Resistance to the new antibiotic ceftazidime-avibactam, which was designed to overcome KPC resistance, had already emerged within a year. Using protein engineering, we uncovered a mechanism by which resistance to this new drug emerges, which could arm scientists with the ability to forestall such resistance to future drugs. Copyright © 2017 Barnes et al.

[Isolation of a carbapenem-resistant K1 serotype Klebsiella pneumonia strain and the study of resistance mechanism].

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Zhang, Rong; Wang, Xuan; Lü, Jianxin

2014-12-16

To study the virulence and mechanism of carbapenem resistance of a clinical isolate of carbapenem-resistant K1 serotype Klebsiella pneumonia strain. Identification of isolate was carried out with VITEK-2 compact system. Antimicrobial susceptibility was determined by E-test; Metallo β-lactamases and carbapenemases screening were conducted by imipenem-EDTA double disc synergy test and modified Hodge test, respectively.Specific polymerehse chain reaction (PCR) and DNA sequencing were preformed to detect the virulence genes including K1, K2, K5, K20, K54, K57, magA, rmpA, wcaG and a series of β-lactamase resistence genes. Conjunction experiment was also performed. The plasmids of transconjugants were submitted to PCR-based replicon typing (PBRT) method. Molecular typing was performed by multilocus sequence typing (MLST). Antimicrobial susceptibility testing revealed that the Klebsiella pneumonia strain was resistant to most of the antibiotics used in clinic. Phynotype confirmary rest revealed the production of carbapanemases, while Metallo β-lactamases were negative; PCR and DNA sequencing confirmed the isolate was positive for blaKPC-2, blaCTX-M-15, blaTEM-1, blaSHV-1 and virulence genes K1, magA, rmpA, wcaG simultaneously; blaKPC-2 was transferred from donor to Escherichia EC600 by conjunction experiment, while no virulence genes were found in the transconjugants. PBRT revealed that Frep plasmid was found in transconjugants. MLST analysis revealed that this strain belonged to ST23. K1 serotype Klebsiella pneumonia strain carries virulence genes and carbapenem resistance gene blaKPC-2, noteworthily the carbapenem resistance genes can be transferred through horizontal transmission on plasmids.

Multicenter Clinical and Molecular Epidemiological Analysis of Bacteremia Due to Carbapenem-Resistant Enterobacteriaceae (CRE) in the CRE Epicenter of the United States.

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Satlin, Michael J; Chen, Liang; Patel, Gopi; Gomez-Simmonds, Angela; Weston, Gregory; Kim, Angela C; Seo, Susan K; Rosenthal, Marnie E; Sperber, Steven J; Jenkins, Stephen G; Hamula, Camille L; Uhlemann, Anne-Catrin; Levi, Michael H; Fries, Bettina C; Tang, Yi-Wei; Juretschko, Stefan; Rojtman, Albert D; Hong, Tao; Mathema, Barun; Jacobs, Michael R; Walsh, Thomas J; Bonomo, Robert A; Kreiswirth, Barry N

2017-04-01

Although the New York/New Jersey (NY/NJ) area is an epicenter for carbapenem-resistant Enterobacteriaceae (CRE), there are few multicenter studies of CRE from this region. We characterized patients with CRE bacteremia in 2013 at eight NY/NJ medical centers and determined the prevalence of carbapenem resistance among Enterobacteriaceae bloodstream isolates and CRE resistance mechanisms, genetic backgrounds, capsular types ( cps ), and antimicrobial susceptibilities. Of 121 patients with CRE bacteremia, 50% had cancer or had undergone transplantation. The prevalences of carbapenem resistance among Klebsiella pneumoniae , Enterobacter spp., and Escherichia coli bacteremias were 9.7%, 2.2%, and 0.1%, respectively. Ninety percent of CRE were K. pneumoniae and 92% produced K. pneumoniae carbapenemase (KPC-3, 48%; KPC-2, 44%). Two CRE produced NDM-1 and OXA-48 carbapenemases. Sequence type 258 (ST258) predominated among KPC-producing K. pneumoniae (KPC- Kp ). The wzi154 allele, corresponding to cps-2 , was present in 93% of KPC-3- Kp , whereas KPC-2- Kp had greater cps diversity. Ninety-nine percent of CRE were ceftazidime-avibactam (CAZ-AVI)-susceptible, although 42% of KPC-3- Kp had an CAZ-AVI MIC of ≥4/4 μg/ml. There was a median of 47 h from bacteremia onset until active antimicrobial therapy, 38% of patients had septic shock, and 49% died within 30 days. KPC-3- Kp bacteremia (adjusted odds ratio [aOR], 2.58; P = 0.045), cancer (aOR, 3.61, P = 0.01), and bacteremia onset in the intensive care unit (aOR, 3.79; P = 0.03) were independently associated with mortality. Active empirical therapy and combination therapy were not associated with survival. Despite a decade of experience with CRE, patients with CRE bacteremia have protracted delays in appropriate therapies and high mortality rates, highlighting the need for rapid diagnostics and evaluation of new therapeutics. Copyright © 2017 American Society for Microbiology.

Emergence of KPC-producing Klebsiella pneumoniae in Italy

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Bossa Maria C

2010-02-01

Full Text Available Abstract Background The emergence of KPC-producing K. pneumoniae has now become a global concern. KPC beta-lactamases are plasmid-borne and, like extended spectrum beta lactamases (ESBLs, can accumulate and transfer resistance determinants to other classes of antibiotics. Therefore, infection control guidelines on early identification and control of the spread of organisms carrying these resistant determinants are needed. Findings Klebsiella pneumoniae carbapenemase (KPC was detected in two isolates of carbapenem-resistant K. pneumoniae obtained from patients at an Italian teaching hospital. The first strain was isolated from a culture drawn from a central venous device (CVC in a patient with Crohn's disease who was admitted to a gastroenterology ward. The second was isolated from a urine sample collected from an indwelling urinary catheter in an intensive care unit (ICU patient with a subdural haematoma. The patients had not travelled abroad. Both isolates were resistant to all β-lactams and were susceptible to imipenem and meropenem but resistant to ertapenem. Isolates also showed resistance to other classes of non-β-lactam antibiotics, such as quinolones, aminoglycosides (with the exception for amikacin, trimethoprim-sulfamethoxazole (TMP-SMX and nitrofurantoin. They were determined to contain the plasmid encoding the carbapenemase gene bla-KPC and were also positive in the Hodge test. Conclusions This is the second report of KPC-producing isolates in Italy, but the first concerning KPC type 2 gene, and it may have important implications for controlling the transmission of microorganisms resistant to antibiotics.

SURVEILLANCE of CARBAPENEM NON-SUSCEPTIBLE GRAM NEGATIVE STRAINS and CHARACTERIZATION of CARBAPENEMASES of CLASSES A, B and D in a LEBANESE HOSPITAL.

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Hammoudi, Dalal; Moubareck, Carole Ayoub; Kanso, Abeer; Nordmann, Patrice; Sarkis, Dolla Karam

2015-01-01

The production of carbapenem-hydrolyzing enzymes has been recognized as one of the most currently relevant resistance mechanisms in gram negative bacterial isolates, and is being detected in various countries. In Lebanon, carbapenem resistance was studied among gram negative pathogens collected from a university hospital from January to June of years 2011 and 2012. All isolates were subjected to phenotypic tests including antibiotic susceptibility, cloxacillin effect, modified Hodge test, and Etest for metallo-β-lactamase detection. They were also subjected to genotyping by PCR sequencing to characterize β-lactamases. Between January and June 2011, 48 carbapenem non-susceptible strains were collected. Of these, one Klebsiella pneumoniae harbored OXA-48 and insertion sequence IS 1999; four Acinetobacter baumanni harbored simultaneously OXA-23 and GES-11, and three Pseudomonas harbored VIM-2 carbapenemase. Between January and June 2012, 100 carbapenem non-susceptible strains were collected. Of these, one K. pneumoniae harbored simultaneously OXA-48, IS 1999, and an acquired AmpC of the ACC group; four Serratia marcescens harbored OXA-48, while among eight A. baumannii, one strain co-harbored OXA-23 and GES-11, six harbored OXA-23 and one OXA-24. Fifteen P, aeruginosa and two Pseudomonas species harbored VIM-2; two P. aeruginosa strains produced IMP-1 and two others IMP-2. This epidemiological survey demonstrates the presence of carbapenemases of Ambler classes A, B, and D in a Lebanese hospital and indicates increase in the number and variety of such enzymes.

Trapping and Characterization of a Reaction Intermediate in Carbapenem Hydrolysis by B. cereus Metallo-β-lactamase

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Tioni, Mariana F.; Llarrull, Leticia I.; Poeylaut-Palena, Andrés A.; Martí, Marcelo A.; Saggu, Miguel; Periyannan, Gopal R.; Mata, Ernesto G.; Bennett, Brian; Murgida, Daniel H.; Vila, Alejandro J.

2009-01-01

Metallo-β-lactamases hydrolyze most β-lactam antibiotics. The lack of a successful inhibitor for them is related to the previous failure to characterize a reaction intermediate with a clinically useful substrate. Stopped-flow experiments together with rapid freeze-quench EPR and Raman spectroscopies were used to characterize the reaction of Co(II)-BcII with imipenem. These studies show that Co(II)-BcII is able to hydrolyze imipenem both in the mono- and dinuclear forms. In contrast to the situation met for penicillin, the species that accumulates during turnover is an enzyme-intermediate adduct in which the β-lactam bond has already been cleaved. This intermediate is a metal-bound anionic species, with a novel resonant structure, that is stabilized by the metal ion at the DCH or Zn2 site. This species has been characterized based on its spectroscopic features. This represents a novel, previously unforeseen intermediate, that is related to the chemical nature of carbapenems, as confirmed by the finding of a similar intermediate for meropenem. Since carbapenems are the only substrates cleaved by B1, B2 and B3 lactamases, the identification of this intermediate could be exploited as a first step towards the design of transition state based inhibitors for all three classes of metallo-β-lactamases. PMID:18980308

A high-throughput screening strategy for nitrile-hydrolyzing enzymes based on ferric hydroxamate spectrophotometry.

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He, Yu-Cai; Ma, Cui-Luan; Xu, Jian-He; Zhou, Li

2011-02-01

Nitrile-hydrolyzing enzymes (nitrilase or nitrile hydratase/amidase) have been widely used in the pharmaceutical industry for the production of carboxylic acids and their derivatives, and it is important to build a method for screening for nitrile-hydrolyzing enzymes. In this paper, a simple, rapid, and high-throughput screening method based on the ferric hydroxamate spectrophotometry has been proposed. To validate the accuracy of this screening strategy, the nitrilases from Rhodococcus erythropolis CGMCC 1.2362 and Alcaligenes sp. ECU0401 were used for evaluating the method. As a result, the accuracy for assaying aliphatic and aromatic carboxylic acids was as high as the HPLC-based method. Therefore, the method may be potentially used in the selection of microorganisms or engineered proteins with nitrile-hydrolyzing enzymes.

Coproduction of KPC-2 and IMP-10 in Carbapenem-Resistant Serratia marcescens Isolates from an Outbreak in a Brazilian Teaching Hospital.

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Silva, Kesia Esther; Cayô, Rodrigo; Carvalhaes, Cecilia Godoy; Patussi Correia Sacchi, Flávia; Rodrigues-Costa, Fernanda; Ramos da Silva, Ana Carolina; Croda, Julio; Gales, Ana Cristina; Simionatto, Simone

2015-07-01

We describe an outbreak caused by KPC-2- and IMP-10-producing Serratia marcescens isolates in a Brazilian teaching hospital. Tigecycline was the only active antimicrobial agent tested. The blaIMP-10 gene was located in a new class 1 integron, named In990, carried by a nonconjugative plasmid, in contrast to blaKPC-2. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Carbapenems and SHV-1 β-Lactamase Form Different Acyl-Enzyme Populations in Crystals and Solution

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Kalp, Matthew; Carey, Paul R.

2009-01-01

The reactions between single crystals of the SHV-1 β-lactamase enzyme and the carbapenems, meropenem, imipenem and ertapenem, have been studied by Raman microscopy. Aided by quantum mechanical calculations, major populations of two acyl-enzyme species, a labile Δ2-pyrroline and a more tightly bound Δ1-pyrroline, have been identified for all three compounds. These isomers differ only in the position of the double bond about the carbapenem nucleus. This discovery is consonant with X-ray crystallographic findings that also identified two populations for meropenem bound in SHV-1: one with the acyl C=O group in the oxyanion hole and the second with the acyl group rotated 180 degrees compared to its expected position [Nukaga, M., Bethel, C. R., Thomson, J. M., Hujer, A. M., Distler, A. M., Anderson, V. E., Knox, J. R., and Bonomo, R. A. (2008) Journal of the American Chemical Society]. When crystals of the Δ1 and Δ2 containing acyl-enzymes were exposed to solutions with no carbapenem, rapid deacylation of the Δ2 species was observed by kinetic Raman experiments. However, no change in the Δ1 population was observed over 1 hour, the effective lifetime of the crystal. These observations lead to the hypothesis that the stable Δ1 species is due to the form seen by X-ray with the acyl carbonyl outside the oxyanion hole, while the Δ2 species corresponds to the form with the carbonyl inside the oxyanion hole. Soak-in and soak-out Raman experiments also demonstrated that tautomeric exchange between the Δ1 and Δ2 forms does not occur on the crystalline enzyme. When meropenem or ertapenem were reacted with SHV-1 in solution, the Raman difference spectra demonstrated that only a major population corresponding to the Δ1 acyl-enzyme could be detected. The 1003 cm-1 mode of the phenyl ring positioned on the C3 side chain of ertapenem acts as an effective internal Raman intensity standard and the ratio of its intensity to that of the 1600 cm-1 feature of Δ1 provides an

Genetic Characterization of Carbapenem-Resistant Enterobacteriaceae and the Spread of Carbapenem-Resistant Klebsiella pneumonia ST340 at a University Hospital in Thailand

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Netikul, Thidarat; Kiratisin, Pattarachai

2015-01-01

Carbapenem-resistant Enterobacteriaceae (CRE) has increasingly spread worldwide in the past decade. The prevalence and characteristics of CRE in Thailand are unknown. In this study, we conducted a 2-year surveillance of CRE among 12,741 clinical isolates of Enterobacteriaceae at the largest university hospital in Thailand with molecular characterization of beta-lactamase (bla) genes, including carbapenemase genes. The CRE prevalence was 1.4%. blaKPC-13 and blaIMP-14a were the only carbapenemase genes detected among these CRE isolates. blaKPC-13 gene was found in a single isolate of Escherichia coli, Enterobacter cloacae and Citrobacter freundii, and blaIMP-14a was found in four isolates of Klebsiella pneumoniae. Carbapenem-resistant K. pneumoniae (CRKP) isolates were resistant to multiple carbapenems at a higher ratio than other CRE species, and thus were further characterized for resistance phenotypes, bla genotypes and molecular epidemiology. Most CRKP isolates harboured multiple bla genes, especially those related to extended-spectrum beta-lactamases. Seven CRKP isolates were resistant to all tested carbapenems, and showed decreased ompK35 and/or ompK36 porin gene expression. Molecular typing of CRKP based on pulsed-field gel electrophoresis (PFGE) demonstrated several unrelated clones. Multilocus sequence typing (MLST) was partially concordant with PFGE results and revealed that ST340, a member of drug-resistant K. pneumoniae clonal complex 258, was the most predominant clone, followed by ST48, ST11 and ST273. The novel ST1645 was identified from this study. ST340 has neither been shown to be predominated among CRKP from other studies, nor been reported in Thailand. Therefore, it emphases a critical concern to monitor and control the spread of CRKP. PMID:26407326

Identification and recombinant expression of anandamide hydrolyzing enzyme from Dictyostelium discoideum

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Neelamegan Dhamodharan

2012-06-01

Full Text Available Abstract Background Anandamide (Arachidonoyl ethanolamide is a potent bioactive lipid studied extensively in humans, which regulates several neurobehavioral processes including pain, feeding and memory. Bioactivity is terminated when hydrolyzed into free arachidonic acid and ethanolamine by the enzyme fatty acid amide hydrolase (FAAH. In this study we report the identification of a FAAH homolog from Dictyostelium discoideum and its function to hydrolyze anandamide. Results A putative FAAH DNA sequence coding for a conserved amidase signature motif was identified in the Dictyostelium genome database and the corresponding cDNA was isolated and expressed as an epitope tagged fusion protein in either E.coli or Dictyostelium. Wild type Dictyostelium cells express FAAH throughout their development life cycle and the protein was found to be predominantly membrane associated. Production of recombinant HIS tagged FAAH protein was not supported in E.coli host, but homologous Dictyostelium host was able to produce the same successfully. Recombinant FAAH protein isolated from Dictyostelium was shown to hydrolyze anandamide and related synthetic fatty acid amide substrates. Conclusions This study describes the first identification and characterisation of an anandamide hydrolyzing enzyme from Dictyostelium discoideum, suggesting the potential of Dictyostelium as a simple eukaryotic model system for studying mechanisms of action of any FAAH inhibitors as drug targets.

Prevalence, characterization and clinical significance of Klebsiella pneumoniae carbapenemase (KPC producing Klebsiella pneumoniae

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: Sarita Nayak, Suman Singh, Soeb Jankhwala, Riddhi Pradhan

2014-11-01

Full Text Available Klebsiella peumoniae, a capsulated gram negative bacillus is responsible for causing life threatening infections in humans. Carbapenems are the drug of choice for serious infection caused by multidrug resistant Klebsiella pneumoniae. The emergence of carbapenem resistance has made it extremely difficult to treat such infections resulting in significant morbidity and mortality. Aims: To study the prevalence of carbapenem resistance using ertapenem as a marker and to detect Klebsiella pneumoniae Carbapenemase (KPC producing Klebsiella pneumoniae as a mechanism of resistance. Material and Methods: The study included 102 patients from which Klebsiella pneumoniae isolated. Identification and antibiotic susceptibility testing of Klebsiella pneumoniae was performed on miniAPI (Analytical Profile Index, Semiautomated bacterial identification system according to Clinical and Laboratory Standards Institute (CLSI guidelines of 2011. The modified Hodge test was performed for detection of Carbapenemase production. Patient’s clinical and demographic details along with risk factors and co-morbid conditions, type of response to antimicrobial therapy and mortality were collected. Results: The prevalence of carbapenem resistance was found to be 30.41% with 16.6% KPC producing Klebsiella pneumoniae. The co-morbid conditions like immunocompromised state (p =0.042, prior antibiotics therapy (p=0.047, previous hospitalization (p =0.021, intensive care unit stay (p=0.047 and use of indwelling devices (p =0.013 were found to be significantly associated with carbapenem resistance. Adverse clinical outcomes (death or worsening among patients infected with ertapenem resistant patients was found to be statistically significant than ertapenem sensitive strains (p =0.008. Conclusions: A high degree of carbapenem resistance in present study is alarming and poses therapeutic dilemmas for clinicians. Initiating timely and appropriate infection control measures along with a

Phenotypic and genotypic characterization of Klebsiella pneumoniae strains with reduced susceptibiliy to carbapenems

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Simone Ambretti

2009-12-01

Full Text Available Reduced susceptibility to carbapenems in Gram-negative pathogens is an emerging feature of the antibiotic-resistance phenomenom Reports about strains resistant to this class of antibiotics among Enterobacteriaceae, particularly in Klebsiella pneumoniae, are increasing.The aims of this study were to assess the incidence of Klebsiella pneumoniae with reduced susceptibility to carbapenems in Bologna area and to carry out the characterization of these strains.The study included isolates of K. pneumoniae that showed reduced susceptibility to carbapenems, as detected by an automated system (Vitek2, bioMérieux. Between January and May 2009, 26 strains were collected (mainly isolated from urinary samples.These isolates were tested for susceptibility to carbapenems by E-test, to define MIC values for meropenem and ertapenem. Moreover, to detect the production of metallo-beta lactamases (MBL and carbapenemases (KPC were respectively performed the Etest with imipenem and imipenem/EDTA (IPM-IPM/EDTA and the modified Hodge test. Susceptibility assays performed by E-test showed that 25/26 strains were susceptible to meropenem, while for ertapenem 20/26 strains resulted resistant.The modified Hodge test was positive for 1 strain, while all the isolates were negative to the IPM-IPM/EDTA E-test.These results show that, as recently reported, the majority of strains of K. pneumoniae exhibiting reduced susceptibility to carbapenems, especially to ertapenem, are characterized by the production of ESBLs, which likely is associated with the loss of porins. On the other side, one strain was found to produce KPC and this finding confirms that the diffusion of carbapenemases producing K. pneumoniae has also to be considered in this geographic area.

Identification of 5'-adenylylimidodiphosphate-hydrolyzing enzyme activity in rabbit taste bud cells using X-ray microanalysis

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Asanuma, N.

1990-01-01

X-ray microanalysis has been used to characterize the enzyme activity hydrolyzing the ATP analogue 5'-adenylylimidodiphosphate (AMP-PNP) in taste bud cells. Rabbit foliate papillae fixed with paraformaldehyde and glutaraldehyde were incubated cytochemically with AMP-PNP as the substrate and lead ion as capture agent. The reaction product which appeared on the microvilli of taste bud cells was examined using an energy dispersive X-ray microanalyzer connected to an analytical electron microscope. The X-ray spectrum thus obtained was compared with that obtained from the product obtained from the demonstration of ATPase activity. Comparison of the phosphorus/lead ratios in the two products showed that twice as much phosphorus was released from an AMP-PNP molecule by the activity in question compared with that released from an ATP molecule by ATPase activity. This indicates that the enzyme hydrolyzes AMP-PNP into AMP and imidodiphosphate and that the enzyme is adenylate cyclase or ATP pyrophosphohydrolase, which possesses a similar hydrolytic property, but not ATPase or alkaline phosphatase, which hydrolyzes AMP-PNP into ADP-NH2 and orthophosphate. This paper provides an example of the use of X-ray microanalysis as a tool for enzyme distinction. The method is applicable to a variety of enzymes and tissues

Kinetic characteristics of polygalacturonase enzymes hydrolyzing galacturonic acid oligomers using isothermal titration calorimetry

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Polygalacturonase enzymes hydrolyze the polygalacturonic acid chains found in pectin. Interest in polygalacturonase enzymes continues as they are useful in a number of industrial processes and conversely, detrimental, as they are involved in maceration of economically important crops. While a good...

Effects of Group 1 versus Group 2 carbapenems on the susceptibility of Acinetobacter baumannii to carbapenems: a before and after intervention study of carbapenem-use stewardship.

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Young Kyung Yoon

Full Text Available OBJECTIVE: Antimicrobial stewardship programs have been proposed for reducing bacterial resistance in the hospital environment. The purpose of this study was to investigate the impact of a carbapenem-use stewardship program on the susceptibility of Acinetobacter baumannii to Group 2 carbapenems. METHODS: A before and after intervention study was conducted at a university hospital from September 2008 to February 2013. Three study periods were defined: Phase I, pre-intervention (months 1-18; Phase II, a postintervention period during which ertapenem use was mandated but carbapenem use was not restricted (months 19-36; and Phase III, a postintervention period during which Group 2 carbapenem use was restricted (months 37-54. RESULTS: During the study period, intervention resulted in diminished consumption of Group 2 carbapenems (antimicrobial use density (AUD: 21.3±6.0 in Phase I, 18.8±6.0 in Phase II, 16.1±4.4 in Phase III; P = 0.028 and increased consumption of ertapenem (AUD: 2.7±1.7 in Phase I, 7.2±4.5 in Phase II, 9.1±5.3 in Phase III; P<0.001. The use of autoregressive-error models showed that in contrast with ertapenem use, the use of Group 2 carbapenem during the previous one month was positively and significantly associated with a subsequent increase in the proportion of carbapenem-resistant A. baumannii (CRAB (P = 0.031. CONCLUSIONS: Implementing a carbapenem-use stewardship program featuring the preferential use of ertapenem for treating appropriate indications of infection resulted in reduced use of Group 2 carbapenems and had a positive impact on the susceptibility of A. baumannii to carbapenems. This approach could be integrated into CRAB-control strategies in hospitals.

Effects of Group 1 versus Group 2 carbapenems on the susceptibility of Acinetobacter baumannii to carbapenems: a before and after intervention study of carbapenem-use stewardship.

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Yoon, Young Kyung; Yang, Kyung Sook; Lee, Seung Eun; Kim, Hyun Jeong; Sohn, Jang Wook; Kim, Min Ja

2014-01-01

Antimicrobial stewardship programs have been proposed for reducing bacterial resistance in the hospital environment. The purpose of this study was to investigate the impact of a carbapenem-use stewardship program on the susceptibility of Acinetobacter baumannii to Group 2 carbapenems. A before and after intervention study was conducted at a university hospital from September 2008 to February 2013. Three study periods were defined: Phase I, pre-intervention (months 1-18); Phase II, a postintervention period during which ertapenem use was mandated but carbapenem use was not restricted (months 19-36); and Phase III, a postintervention period during which Group 2 carbapenem use was restricted (months 37-54). During the study period, intervention resulted in diminished consumption of Group 2 carbapenems (antimicrobial use density (AUD): 21.3±6.0 in Phase I, 18.8±6.0 in Phase II, 16.1±4.4 in Phase III; P = 0.028) and increased consumption of ertapenem (AUD: 2.7±1.7 in Phase I, 7.2±4.5 in Phase II, 9.1±5.3 in Phase III; Pcarbapenem during the previous one month was positively and significantly associated with a subsequent increase in the proportion of carbapenem-resistant A. baumannii (CRAB) (P = 0.031). Implementing a carbapenem-use stewardship program featuring the preferential use of ertapenem for treating appropriate indications of infection resulted in reduced use of Group 2 carbapenems and had a positive impact on the susceptibility of A. baumannii to carbapenems. This approach could be integrated into CRAB-control strategies in hospitals.

Complete Sequence of Four Multidrug-Resistant MOBQ1 Plasmids Harboring blaGES-5 Isolated from Escherichia coli and Serratia marcescens Persisting in a Hospital in Canada.

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Boyd, David; Taylor, Geoffrey; Fuller, Jeff; Bryce, Elizabeth; Embree, Joanne; Gravel, Denise; Katz, Kevin; Kibsey, Pamela; Kuhn, Magdalena; Langley, Joanne; Mataseje, Laura; Mitchell, Robyn; Roscoe, Diane; Simor, Andrew; Thomas, Eva; Turgeon, Nathalie; Mulvey, Michael

2015-06-01

The usefulness of carbapenems for gram-negative infections is becoming compromised by organisms harboring carbapenemases, enzymes which can hydrolyze the drug. Currently KPC (class A), NDM (class B), and OXA-48 types (class D) are the most globally widespread carbapenemases. However, among the GES-type class A extended-spectrum β-lactamases (ESBLs) there are variants that hydrolyze carbapenems, with blaGES-5 being the most common. Two Escherichia coli and two Serratia marcescens harboring blaGES-5 on plasmids were isolated by the Canadian Nosocomial Infection Surveillance Program (CNISP) from four different patients in a single hospital over a 2-year period. Complete sequencing of the blaGES-5 plasmids indicated that all four had nearly identical backbones consisting of genes for replication, partitioning, and stability, but contained variant accessory regions consisting of mobile elements and antimicrobial resistance genes. The plasmids were of a novel replicon type, but belonged to the MOBQ1 group based on relaxase sequences, and appeared to be mobilizable, but not self-transmissible. Considering the time periods of bacterial isolation, it would appear the blaGES-5 plasmid has persisted in an environmental niche for at least 2 years in the hospital. This has implications for infection control and clinical care when it is transferred to clinically relevant gram-negative organisms.

Update on Marine Carbohydrate Hydrolyzing Enzymes: Biotechnological Applications

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Antonio Trincone

2018-04-01

Full Text Available After generating much interest in the past as an aid in solving structural problems for complex molecules such as polysaccharides, carbohydrate-hydrolyzing enzymes of marine origin still appear as interesting biocatalysts for a range of useful applications in strong interdisciplinary fields such as green chemistry and similar domains. The multifaceted fields in which these enzymes are of interest and the scarce number of original articles in literature prompted us to provide the specialized analysis here reported. General considerations from modern (2016–2017 interval time review articles are at start of this manuscript; then it is subsequently organized in sections according to particular biopolymers and original research articles are discussed. Literature sources like the Science Direct database with an optimized W/in search, and the Espacenet patent database were used.

Emergence and mechanism of carbapenem-resistant Escherichia coli in Henan, China, 2014

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Wen-juan Liang

2018-05-01

Full Text Available The emergence and dissemination of carbapenem-resistant Escherichia coli (E. coli strains is a main risk for global public health, but little is known of carbapenemase producing E. coli in Henan, China. The study was undertaken to investigate the prevalence and mechanism of carbapenem-resistant E. coli strains in a hospital in Xinxiang, Henan, China, 2014. A total of 5 carbapenemase-producing E. coli strains were screened from 1014 isolates. We found that they were all resistant to meropenem and imipenem. Amikacin showed the best sensitivity, with gentamicin coming up next. The positive rate of blaNDM was 80% (4/5. The sequencing results showed that two isolates belonged to blaNDM-1 whereas other 2 isolates carried the blaNDM-5. Other carbapenemase genes including blaIMP, blaVIM, blaKPC and blaOXA-48 were not detected. The blaCTX-M-15, blaTEM-1, sul2, aad, and aac(6”–Ib–cr were also detected. MLST analysis showed that NDM-producing E. coli were sporadic. Conjugation test indicated blaNDM could be transferred. In conclusion, the blaNDM was the principal resistance mechanism of carbapenem-resistant E. coli in the hospital, Henan, China. Keywords: blaNDM, Carbapenem-resistant, Escherichia coli

Protein Hydrolysis from Catfish Prepared by Papain Enzyme and Antioxidant Activity of Hydrolyzate

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Ace Baehaki

2015-12-01

Full Text Available The objective of this research was to make a protein hydrolysates from catfish (Pangasius pangasius enzymatically using papain enzyme and analyzed the antioxidant activity of protein hydrolysates produced. The research used the method completely randomized design with two replications the treatment were the difference concentration of the papain enzyme (0%, 1%, 2%, 3%, 4%, 5%, and 6%. The parameters of research were antioxidative activity using DPPH (2,2-difenil-1–pikrilhidrazil, protein content, and molecular weight using SDS-PAGE (Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis. The results showed that catfish protein hydrolysates prepared by papain enzyme has antioxidative activity. The highest degree of hydrolysis was 71.98% at enzyme concentration of 6%. Based on the DPPH scavenging method catfish protein hydrolysates has the antioxidative activity with the value 37.85-67.62%. The protein content of catfish protein hydrolysates were 20.86-54.47 mg/ml. The molecular weight of catfish protein hydrolyzates were 11.90-65.20 kDa.

Outbreak by ventilator-associated ST11 K. pneumoniae with co-production of CTX-M-24 and KPC-2 in SICU of a tertiary teaching hospital in central China

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Longhua Hu

2016-08-01

Full Text Available The emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP often responsible for numerous hospital-associated outbreaks has become an important public health problem. From January 2013 to February 2014, a total of 41 non-duplicate K. pneumoniae isolates with carbapenem resistance, were collected at a tertiary teaching hospital in Nanchang, central China. Among 41 K. pneumoniae isolates, 28 were isolated from hospitalized patients including 19 from the patients in surgery intensive care unit (SICU and 13 were isolated from ventilators. Twenty-four of 28 patients infected by CRKP have been submitted to mechanical ventilation using ventilator. More than 95% of the CRKP isolates were resistant to 13 antimicrobials tested.All CRKP isolates were confirmed as carbapenemase producer and were positive for blaKPC-2, with one positive for both blaKPC-2 and blaNDM-1. All carbapenemase-producing isolates harbored at least one of extended spectrum βlactamase genes tested, among which95.1% (39/41 of the tested isolates were found to harbor both blaCTX-M-24 and blaKPC-2, Of note, one isolate harbored simultaneously two carbapenemase genes (blaKPC-2 and blaNDM-1 and two ESBL genes (blaCTX-M-3 and blaTEM-104 . To the best of our knowledge, coexistence of blaKPC-2 and blaCTX-M-24 in one isolate is first reported. MLST results showed that 41 CRKP isolates belonged to 4 sequence types (STs including ST11, novel ST1854, novel ST1855 and ST1224. PFGE results displayed 3 PFGE clusters. Thirty-eight ST11 CRKP isolates (92.7%, 38/41 including all 13 isolates from ventilators and 25 isolates from patients from 7 wards (18 from是ICU belonged to same PFGE cluster, indicating these isolates were clonally related. Fifteen isolates have an identical undistinguished pattern (100% similarity forming a single clonal population. Moreover, this clone was exclusively linked to the cases attended in SICU and linked to the Ventilators. Additionally, the other SICU cases were

Microbiological Features of KPC-Producing Enterobacter Isolates Identified in a U.S. Hospital System

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Ahn, Chulsoo; Syed, Alveena; Hu, Fupin; O’Hara, Jessica A.; Rivera, Jesabel I.; Doi, Yohei

2014-01-01

Microbiological data regarding KPC-producing Enterobacter spp. are scarce. In this study, 11 unique KPC-producing Enterobacter isolates were identified among 44 ertapenem-non-susceptible Enterobacter isolates collected between 2009 and 2013 at a hospital system in Western Pennsylvania. All cases were healthcare-associated and occurred in medically complex patients. While pulsed-field gel electrophoresis (PFGE) showed diverse restriction patterns overall, multilocus sequence typing (MLST) identified Enterobacter cloacae isolates with sequence types (STs) 93 and 171 from two hospitals each. The levels of carbapenem minimum inhibitory concentrations were highly variable. All isolates remained susceptible to colistin, tigecycline, and the majority to amikacin and doxycycline. A blaKPC-carrying IncN plasmid conferring trimethoprim-sulfamethoxazole resistance was identified in three of the isolates. Spread of blaKPC in Enterobacter spp. appears to be due to a combination of plasmid-mediated and clonal processes. PMID:25053203

Enzyme characteristics of aminotransferase FumI of Sphingopyxis sp. MTA144 for deamination of hydrolyzed fumonisin B₁.

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Hartinger, Doris; Schwartz, Heidi; Hametner, Christian; Schatzmayr, Gerd; Haltrich, Dietmar; Moll, Wulf-Dieter

2011-08-01

Fumonisins are carcinogenic mycotoxins that are frequently found as natural contaminants in maize from warm climate regions around the world. The aminotransferase FumI is encoded as part of a gene cluster of Sphingopyxis sp. MTA144, which enables this bacterial strain to degrade fumonisin B(1) and related fumonisins. FumI catalyzes the deamination of the first intermediate of the catabolic pathway, hydrolyzed fumonisin B(1). We used a preparation of purified, His-tagged FumI, produced recombinantly in Escherichia coli in soluble form, for enzyme characterization. The structure of the reaction product was studied by NMR and identified as 2-keto hydrolyzed fumonisin B(1). Pyruvate was found to be the preferred co-substrate and amino group receptor (K (M) = 490 μM at 10 μM hydrolyzed fumonisin B(1)) of FumI, but other α-keto acids were also accepted as co-substrates. Addition of the co-enzyme pyridoxal phosphate to the enzyme preparation enhanced activity, and saturation was already reached at the lowest tested concentration of 10 μM. The enzyme showed activity in the range of pH 6 to 10 with an optimum at pH 8.5, and in the range of 6°C to 50°C with an optimum at 35°C. The aminotransferase worked best at low salt concentration. FumI activity could be recovered after preincubation at pH 4.0 or higher, but not lower. The aminotransferase was denatured after preincubation at 60°C for 1 h, and the residual activity was also reduced after preincubation at lower temperatures. At optimum conditions, the kinetic parameters K (M) = 1.1 μM and k (cat) = 104/min were determined with 5 mM pyruvate as co-substrate. Based on the enzyme characteristics, a technological application of FumI, in combination with the fumonisin carboxylesterase FumD for hydrolysis of fumonisins, for deamination and detoxification of hydrolyzed fumonisins seems possible, if the enzyme properties are considered.

Phenotypic and molecular detection of the bla KPC gene in clinical isolates from inpatients at hospitals in São Luis, MA, Brazil.

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Ribeiro, Patricia Cristina Saldanha; Monteiro, Andrea Souza; Marques, Sirlei Garcia; Monteiro, Sílvio Gomes; Monteiro-Neto, Valério; Coqueiro, Martina Márcia Melo; Marques, Ana Cláudia Garcia; de Jesus Gomes Turri, Rosimary; Santos, Simone Gonçalves; Bomfim, Maria Rosa Quaresma

2016-12-07

Bacteria that produce Klebsiella pneumoniae carbapenemases (KPCs) are resistant to broad-spectrum β-lactam antibiotics. The objective of this study was to phenotypically and genotypically characterize the antibiotic susceptibility to carbapenems of 297 isolates recovered from clinical samples obtained from inpatients at 16 hospitals in São Luis (Maranhão, Brazil). The study was conducted using phenotypic tests and molecular methods, including polymerase chain reaction (PCR), sequencing and enterobacterial repetitive intergenic consensus (ERIC)-PCR. The nonparametric chi-square test of independence was used to evaluate the associations between the bacterial bla KPC gene and the modified Hodge test, and the chi-square adherence test was used to assess the frequency of carbapenemases and their association with the bla KPC gene. The most frequently isolated species were Acinetobacter baumannii (n = 128; 43.0%), K. pneumoniae (n = 75; 25.2%), and Pseudomonas aeruginosa (n = 42; 14.1%). Susceptibility assays showed that polymixin B was active against 89.3% of the bacterial isolates. The Acinetobacter spp. and K. pneumoniae strains were susceptible to amikacin and tigecycline, and Pseudomonas spp. were sensitive to gentamicin and amikacin. Among the 297 isolates, 100 (33.7%) were positive for the bla KPC gene, including non-fermentative bacteria (A. baumannii) and Enterobacteriaceae species. Among the isolates positive for the bla KPC gene, K. pneumoniae isolates had the highest positivity rate of 60.0%. The bla KPC gene variants detected included KPC-2, which was found in all isolates belonging to species of the Enterobacteriaceae family. KPC-2 and KPC-3 were observed in A. baumannii isolates. Importantly, the bla KPC gene was also detected in three Raoultella isolates and one isolate of the Pantoea genus. ERIC-PCR patterns showed a high level of genetic diversity among the bacterial isolates; it was capable of distinguishing 34 clones among 100 strains

Effect of γ-rays irradiation and alkali solution pretreatment on hydrolyzing enzyme and microcosmic structure of core straw

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Tang Hongtao; Wang Feng; Li Weiming; Li An; Ha Yiming; Li Yanjie

2012-01-01

To increase yield of reducing sugar enzymatic hydrolyzed from corn straw yield of corn stalk on Enzymatic hydrolysis, γ-rays radiation and NaOH solution pretreatment were used. The changes of microstructure of the corn straw before and after pretreatments were characterized by IR, X-rays diffraction and SEM. The results shows that the γ-rays radiation can significantly decrease the essential concentration of NaOH solution and shorten the immersion time, but it could not affected the yield of reducing sugar remarkably. The scanning electron microscopy (SEM) results show that the sample which was treated at the 200 kGy irradiation dose and NaOH solution circumstance has the biggest surface area increase. The reducing sugar content of enzyme hydrolyzed corn straw treated at 200 kGy irradiation dose and 2% NaOH solution was achieved 48.34%, which provides the theoretical basis for industry ethanol production using enzyme hydrolyzed corn straw. (authors)

Characterization of carbapenem-resistant Gram-negative bacteria from Tamil Nadu.

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Nachimuthu, Ramesh; Subramani, Ramkumar; Maray, Suresh; Gothandam, K M; Sivamangala, Karthikeyan; Manohar, Prasanth; Bozdogan, Bülent

2016-10-01

Carbapenem resistance is disseminating worldwide among Gram-negative bacteria. The aim of this study was to identify carbapenem-resistance level and to determine the mechanism of carbapenem resistance among clinical isolates from two centres in Tamil Nadu. In the present study, a total of 93 Gram-negative isolates, which is found to be resistant to carbapenem by disk diffusion test in two centres, were included. All isolates are identified at species level by 16S rRNA sequencing. Minimal inhibitory concentrations (MICs) of isolates for Meropenem were tested by agar dilution method. Presence of blaOXA, blaNDM, blaVIM, blaIMP and blaKPC genes was tested by PCR in all isolates. Amplicons were sequenced for confirmation of the genes. Among 93 isolates, 48 (%52) were Escherichia coli, 10 (%11) Klebsiella pneumoniae, nine (%10) Pseudomonas aeruginosa. Minimal inhibitory concentration results showed that of 93 suspected carbapenem-resistant isolates, 27 had meropenem MICs ≥ 2 μg/ml. The MIC range, MIC50 and MIC90 were 128 μg/ml, 0.12 and 16 μg/ml, respectively. Fig. 1 . Among meropenem-resistant isolates, E. coli were the most common (9/48, 22%), followed by K. pneumoniae (7/9, 77%), P. aeruginosa (6/10, 60%), Acinetobacter baumannii (2/2, 100%), Enterobacter hormaechei (2/3, 67%) and one Providencia rettgeri (1/1, 100%). PCR results showed that 16 of 93 carried blaNDM, three oxa181, and one imp4. Among blaNDM carriers, nine were E. coli, four Klebsiella pneumoniae, two E. hormaechei and one P. rettgeri. Three K. pneumoniae were OXA-181 carriers. The only imp4 carrier was P. aeruginosa. A total of seven carbapenem-resistant isolates were negatives by PCR for the genes studied. All carbapenem-resistance gene-positive isolates had meropenem MICs >2 μg/ml. Our results confirm the dissemination of NDM and emergence of OXA-181 beta-lactamase among Gram-negative bacteria in South India. This study showed the emergence of NDM producer in clinical isolates of E

A general reaction mechanism for carbapenem hydrolysis by mononuclear and binuclear metallo-β-lactamases.

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Lisa, María-Natalia; Palacios, Antonela R; Aitha, Mahesh; González, Mariano M; Moreno, Diego M; Crowder, Michael W; Bonomo, Robert A; Spencer, James; Tierney, David L; Llarrull, Leticia I; Vila, Alejandro J

2017-09-14

Carbapenem-resistant Enterobacteriaceae threaten human health, since carbapenems are last resort drugs for infections by such organisms. Metallo-β-lactamases (MβLs) are the main mechanism of resistance against carbapenems. Clinically approved inhibitors of MBLs are currently unavailable as design has been limited by the incomplete knowledge of their mechanism. Here, we report a biochemical and biophysical study of carbapenem hydrolysis by the B1 enzymes NDM-1 and BcII in the bi-Zn(II) form, the mono-Zn(II) B2 Sfh-I and the mono-Zn(II) B3 GOB-18. These MβLs hydrolyse carbapenems via a similar mechanism, with accumulation of the same anionic intermediates. We characterize the Michaelis complex formed by mono-Zn(II) enzymes, and we identify all intermediate species, enabling us to propose a chemical mechanism for mono and binuclear MβLs. This common mechanism open avenues for rationally designed inhibitors of all MβLs, notwithstanding the profound differences between these enzymes' active site structure, β-lactam specificity and metal content.Carbapenem-resistant bacteria pose a major health threat by expressing metallo-β-lactamases (MβLs), enzymes able to hydrolyse these life-saving drugs. Here the authors use biophysical and computational methods and show that different MβLs share the same reaction mechanism, suggesting new strategies for drug design.

Hydrolysis of native and heat-treated starches at sub-gelatinization temperature using granular starch hydrolyzing enzyme.

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Uthumporn, U; Shariffa, Y N; Karim, A A

2012-03-01

The effect of heat treatment below the gelatinization temperature on the susceptibility of corn, mung bean, sago, and potato starches towards granular starch hydrolysis (35°C) was investigated. Starches were hydrolyzed in granular state and after heat treatment (50°C for 30 min) by using granular starch hydrolyzing enzyme for 24 h. Hydrolyzed heat-treated starches showed a significant increase in the percentage of dextrose equivalent compared to native starches, respectively, with corn 53% to 56%, mung bean 36% to 47%, sago 15% to 26%, and potato 12% to 15%. Scanning electron microscopy micrographs showed the presence of more porous granules and surface erosion in heat-treated starch compared to native starch. X-ray analysis showed no changes but with sharper peaks for all the starches, suggested that hydrolysis occurred on the amorphous region. The amylose content and swelling power of heat-treated starches was markedly altered after hydrolysis. Evidently, this enzyme was able to hydrolyze granular starches and heat treatment before hydrolysis significantly increased the degree of hydrolysis.

[Risk factors for Pseudomonas aeruginosa infections, resistant to carbapenem].

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Ghibu, Laura; Miftode, Egidia; Teodor, Andra; Bejan, Codrina; Dorobăţ, Carmen Mihaela

2010-01-01

Since their introduction in clinical practice,carbapenems have been among the most powerful antibiotics for treating serious infections cased by Gram-negative nosocomial pathogens, including Pseudomonas aeruginosa. The emergence of betalactamases with carbapenem-hydrolyzing activity is of major clinical concern. Pseudomonas aeruginosa is a leading cause of nosocomial infection. Risk factors for colonization with carbapenems-resistant Pseudomonas in hospital are: history of P. aeruginosa infection or colonization within the previous year, (length of hospital stay, being bedridden or in the ICU, mechanical ventilation, malignant disease, and history of chronic obstructive pulmonary disease have all been identified as independent risk factors for MDR P. aeruginosa infection. Long-term-care facilities are also reservoirs of resistant bacteria. Risk factors for colonization of LTCF residents with resistant bacteria included age > 86 years, antibiotic treatment in the previous 3 months, indwelling devices, chronic obstructive pulmonary disease, physical disability, and the particular LTCF unit.

Molecular insight on the non-covalent interactions between carbapenems and uc(l,d)-transpeptidase 2 from Mycobacterium tuberculosis: ONIOM study

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Ntombela, Thandokuhle; Fakhar, Zeynab; Ibeji, Collins U.; Govender, Thavendran; Maguire, Glenn E. M.; Lamichhane, Gyanu; Kruger, Hendrik G.; Honarparvar, Bahareh

2018-05-01

Tuberculosis remains a dreadful disease that has claimed many human lives worldwide and elimination of the causative agent Mycobacterium tuberculosis also remains elusive. Multidrug-resistant TB is rapidly increasing worldwide; therefore, there is an urgent need for improving the current antibiotics and novel drug targets to successfully curb the TB burden. uc(l,d)-Transpeptidase 2 is an essential protein in Mtb that is responsible for virulence and growth during the chronic stage of the disease. Both uc(d,d)- and uc(l,d)-transpeptidases are inhibited concurrently to eradicate the bacterium. It was recently discovered that classic penicillins only inhibit uc(d,d)-transpeptidases, while uc(l,d)-transpeptidases are blocked by carbapenems. This has contributed to drug resistance and persistence of tuberculosis. Herein, a hybrid two-layered ONIOM (B3LYP/6-31G+(d): AMBER) model was used to extensively investigate the binding interactions of LdtMt2 complexed with four carbapenems (biapenem, imipenem, meropenem, and tebipenem) to ascertain molecular insight of the drug-enzyme complexation event. In the studied complexes, the carbapenems together with catalytic triad active site residues of LdtMt2 (His187, Ser188 and Cys205) were treated at with QM [B3LYP/6-31+G(d)], while the remaining part of the complexes were treated at MM level (AMBER force field). The resulting Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) for all complexes showed that the carbapenems exhibit reasonable binding interactions towards LdtMt2. Increasing the number of amino acid residues that form hydrogen bond interactions in the QM layer showed significant impact in binding interaction energy differences and the stabilities of the carbapenems inside the active pocket of LdtMt2. The theoretical binding free energies obtained in this study reflect the same trend of the experimental observations. The electrostatic, hydrogen bonding and Van der Waals interactions between the carbapenems and Ldt

Single or in Combination Antimicrobial Resistance Mechanisms of Klebsiella pneumoniae Contribute to Varied Susceptibility to Different Carbapenems

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Tsai, Yu-Kuo; Liou, Ci-Hong; Fung, Chang-Phone; Lin, Jung-Chung; Siu, L. Kristopher

2013-01-01

Resistance to carbapenems has been documented by the production of carbapenemase or the loss of porins combined with extended-spectrum β-lactamases or AmpC β-lactamases. However, no complete comparisons have been made regarding the contributions of each resistance mechanism towards carbapenem resistance. In this study, we genetically engineered mutants of Klebsiella pneumoniae with individual and combined resistance mechanisms, and then compared each resistance mechanism in response to ertapenem, imipenem, meropenem, doripenem and other antibiotics. Among the four studied carbapenems, ertapenem was the least active against the loss of porins, cephalosporinases and carbapenemases. In addition to the production of KPC-2 or NDM-1 alone, resistance to all four carbapenems could also be conferred by the loss of two major porins, OmpK35 and OmpK36, combined with CTX-M-15 or DHA-1 with its regulator AmpR. Because the loss of OmpK35/36 alone or the loss of a single porin combined with bla CTX-M-15 or bla DHA-1-ampR expression was only sufficient for ertapenem resistance, our results suggest that carbapenems other than ertapenem should still be effective against these strains and laboratory testing for non-susceptibility to other carbapenems should improve the accurate identification of these isolates. PMID:24265784

Identification and characterization of a novel thermostable pyrethroid-hydrolyzing enzyme isolated through metagenomic approach

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Fan Xinjiong

2012-03-01

Full Text Available Abstract Background Pyrethroid pesticides are broad-spectrum pest control agents in agricultural production. Both agricultural and residential usage is continuing to grow, leading to the development of insecticide resistance in the pest and toxic effects on a number of nontarget organisms. Thus, it is necessary to hunt suitable enzymes including hydrolases for degrading pesticide residues, which is an efficient "green" solution to biodegrade polluting chemicals. Although many pyrethroid esterases have consistently been purified and characterized from various resources including metagenomes and organisms, the thermostable pyrethroid esterases have not been reported up to the present. Results In this study, we identified a novel pyrethroid-hydrolyzing enzyme Sys410 belonging to familyV esterases/lipases with activity-based functional screening from Turban Basin metagenomic library. Sys410 contained 280 amino acids with a predicted molecular mass (Mr of 30.8 kDa and was overexpressed in Escherichia coli BL21 (DE3 in soluble form. The optimum pH and temperature of the recombinant Sys410 were 6.5 and 55°C, respectively. The enzyme was stable in the pH range of 4.5-8.5 and at temperatures below 50°C. The activity of Sys410 decreased a little when stored at 4°C for 10 weeks, and the residual activity reached 94.1%. Even after incubation at 25°C for 10 weeks, it kept 68.3% of its activity. The recombinant Sys410 could hydrolyze a wide range of ρ-nitrophenyl esters, but its best substrate is ρ-nitrophenyl acetate with the highest activity (772.9 U/mg. The enzyme efficiently degraded cyhalothrin, cypermethrin, sumicidin, and deltamethrin under assay conditions of 37°C for 15 min, with exceeding 95% hydrolysis rate. Conclusion This is the first report to construct metagenomic libraries from Turban Basin to obtain the thermostable pyrethroid-hydrolyzing enzyme. The recombinant Sys410 with broad substrate specificities and high activity was the most

Nitrile-hydrolyzing enzyme from Meyerozyma guilliermondii and its potential in biosynthesis of 3-hydroxypropionic acid.

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Zhang, Qiang; Gong, Jin-Song; Dong, Ting-Ting; Liu, Ting-Ting; Li, Heng; Dou, Wen-Fang; Lu, Zhen-Ming; Shi, Jin-Song; Xu, Zheng-Hong

2017-06-01

3-Hydroxypropionic acid (3-HP) is an important platform chemical in organic synthesis. Traditionally, 3-HP was produced by chemical methods and fermentation process. In this work, a novel enzymatic method was developed for green synthesis of 3-HP. A yeast strain harboring nitrile-hydrolyzing enzyme was newly isolated from environmental samples using 3-hydroxypropionitrile (3-HPN) as the sole nitrogen source. It was identified to be Meyerozyma guilliermondii CGMCC12935 by sequencing of the 18S ribosomal DNA and internal transcribed spacer, together with analysis of the morphology characteristics. The catalytic properties of M. guilliermondii CGMCC12935 resting cells were determined, and the optimum activity was achieved at 55 °C and pH 7.5. The enzyme showed broad substrate specificity towards nitriles, especially 3-HPN, aminoacetonitrile and 3-cyanopyridine. The presence of Ag + , Pb 2+ and excess substrate inhibited the enzyme activity, whereas 5% (v/v) ethyl acetate had a positive effect on the enzyme activity. M. guilliermondii CGMCC12935 resting cells by addition of 3% glucose could thoroughly hydrolyze 500 mM 3-HPN into 3-HP within 100 h and the maximal accumulative production of 3-HP reached 216.33 mM, which was over twofolds than the control group with no additional glucose. And this work would lay the foundation for biological production of 3-HP in industry.

Audit of carbapenem prescriptions comparing 2 assessment periods.

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Lefébure, A; Papy, E; Rioux, C; Diamantis, S; Armand-Lefèvre, L; Longuet, P; Lescure, F X; Wolff, M; Arnaud, P; Lucet, J C

2015-07-01

The emergence of extended-spectrum beta-lactamase (ESBL) producing Enterobacteriaceae has resulted in the increase of carbapenem prescriptions. The objective of our study was to determine the appropriateness of carbapenem prescriptions from initiation to reassessment of treatment, between 2009 and 2011. A questionnaire drafted by infectious diseases specialists (IDS) and microbiologists was used to collect clinical and microbiological data concerning carbapenem prescriptions in 2009 and 2011. An IDS then compared the results to assess carbapenem prescription compliance with our hospital's local recommendations. Seventy-one prescriptions were included in 2009 and 32 in 2011. The carbapenem treatment had been most frequently probabilistic to treat nosocomial infections. The microbiological data revealed that the number of multidrug-resistant (MDR) infections had increased between 2009 and 2011, especially infections involving ESBL-producing Enterobacteriaceae. At treatment reassessment, in 2009 and 2011, 15 (21%) and 12 (38%) carbapenem prescriptions were appropriate and continued. Overall, when comparing the 2 periods, prescriptions complied with local guidelines from initiation to reassessment of treatment without any statistically significant difference (68% in 2009 and 75% in 2011). Our study results showed that MDR infections had increased and especially infections due to ESBL-producing Enterobacteriaceae; this was consistent with epidemiological data. We also proved that most carbapenem prescriptions were compliant with recommendations. The increased mobile IDS interventions in medical and surgical departments helped reach this rate of compliance. Carbapenem stewardship may be promoted even in a difficult epidemiological context, especially with IDS interventions for the duration of treatment or at treatment reassessment. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Biochemical and Structural Characterization of Mycobacterium tuberculosis beta-Lactamase with the Carbapenems Ertapenem and Doripenem

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L Tremblay; F Fan; J Blanchard

2011-12-31

Despite the enormous success of {beta}-lactams as broad-spectrum antibacterials, they have never been widely used for the treatment of tuberculosis (TB) due to intrinsic resistance that is caused by the presence of a chromosomally encoded gene (blaC) in Mycobacterium tuberculosis. Our previous studies of TB BlaC revealed that this enzyme is an extremely broad-spectrum {beta}-lactamase hydrolyzing all {beta}-lactam classes. Carbapenems are slow substrates that acylate the enzyme but are only slowly deacylated and can therefore act also as potent inhibitors of BlaC. We conducted the in vitro characterization of doripenem and ertapenem with BlaC. A steady-state kinetic burst was observed with both compounds with magnitudes proportional to the concentration of BlaC used. The results provide apparent K{sub m} and k{sub cat} values of 0.18 {micro}M and 0.016 min{sup -1} for doripenem and 0.18 {micro}M and 0.017 min{sup -1} for ertapenem, respectively. FTICR mass spectrometry demonstrated that the doripenem and ertapenem acyl-enzyme complexes remain stable over a time period of 90 min. The BlaC-doripenem covalent complex obtained after a 90 min soak was determined to 2.2 {angstrom}, while the BlaC-ertapenem complex obtained after a 90 min soak was determined to 2.0 {angstrom}. The 1.3 {angstrom} diffraction data from a 10 min ertapenem-soaked crystal revealed an isomerization occurring in the BlaC-ertapenem adduct in which the original {Delta}2-pyrroline ring was tautomerized to generate the {Delta}1-pyrroline ring. The isomerization leads to the flipping of the carbapenem hydroxyethyl group to hydrogen bond to carboxyl O2 of Glu166. The hydroxyethyl flip results in both the decreased basicity of Glu166 and a significant increase in the distance between carboxyl O2 of Glu166 and the catalytic water molecule, slowing hydrolysis.

Double Copies of bla(KPC-3)::Tn4401a on an IncX3 Plasmid in Klebsiella pneumoniae Successful Clone ST512 from Italy.

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Fortini, Daniela; Villa, Laura; Feudi, Claudia; Pires, João; Bonura, Celestino; Mammina, Caterina; Endimiani, Andrea; Carattoli, Alessandra

2016-01-01

A carbapenem-resistant sequence type 512 (ST512) Klebsiella pneumoniae carbapenemase 3 (KPC-3)-producing K. pneumoniae strain showing a novel variant plasmid content was isolated in Palermo, Italy, in 2014. ST512 is a worldwide successful clone associated with the spread of bla(KPC) genes located on the IncFIIk pKpQIL plasmid. In our ST512 strain, the bla(KPC-3) gene was unusually located on an IncX3 plasmid, whose complete sequence was determined. Two copies of bla(KPC-3)::Tn4401a caused by intramolecular transposition events were detected in the plasmid. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Screening of nursing home residents for colonization with carbapenem-resistant Enterobacteriaceae admitted to acute care hospitals: Incidence and risk factors.

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Cunha, Cheston B; Kassakian, Steven Z; Chan, Ryan; Tenover, Fred C; Ziakas, Panos; Chapin, Kimberle C; Mermel, Leonard A

2016-02-01

There are increasing reports of multidrug-resistant gram-negative bacilli in nursing homes and acute care hospitals. We performed a point prevalence survey to detect fecal carriage of gram-negative bacteria carrying carbapenem resistance genes or which were otherwise resistant to carbapenem antibiotics among 500 consecutive admissions from local nursing homes to 2 hospitals in Providence, Rhode Island. We performed a case-control study to identify risk factors associated with carriage of carbapenem-resistant Enterobacteriaceae (CRE). There were 404 patients with 500 hospital admissions during which they had rectal swab samples cultured. Fecal carriage of any carbapenem-resistant or carbapenemase- producing gram-negative bacteria was found in 23 (4.6%) of the 500 hospital admissions, including 7 CRE (1.4%), 2 (0.4%) of which were Klebsiella pneumoniae carbapenemase (ie, blaKPC) producing (CPE) Citrobacter freundii, 1 of which was carbapenem susceptible by standard testing methods. Use of a gastrostomy tube was associated with CRE carriage (P = .04). We demonstrated fecal carriage of carbapenem-resistant or carbapenemase-producing gram-negative bacteria in 4.6% of nursing home patients admitted to 2 acute care hospitals, but only 0.4% of such admissions were patients with fecal carriage of CPE. Use of gastrostomy tubes was associated with fecal carriage of gram-negative bacteria with detectable carbapenem resistance. CRE fecal carriage is uncommon in our hospital admissions from nursing homes. Copyright © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Use of Imipenem To Detect KPC, NDM, OXA, IMP, and VIM Carbapenemase Activity from Gram-Negative Rods in 75 Minutes Using Liquid Chromatography-Tandem Mass Spectrometry

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Kulkarni, M. V.; Zurita, A. N.; Pyka, J. S.; Murray, T. S.; Hodsdon, M. E.

2014-01-01

Resistance to extended-spectrum β-lactam antibiotics has led to a greater reliance upon carbapenems, but the expression of carbapenemases threatens to limit the utility of these drugs. Current methods to detect carbapenemase activity are suboptimal, requiring prolonged incubations during which ineffective therapy may be prescribed. We previously described a sensitive and specific assay for the detection of carbapenemase activity using ertapenem and liquid chromatography-tandem mass spectrometry (LC-MS/MS). In this study, we assessed 402 Gram-negative rods, including both Enterobacteriaceae and non-Enterobacteriaceae expressing IMP, VIM, KPC, NDM, and/or OXA carbapenemases, by using imipenem, meropenem, and ertapenem with LC-MS/MS assays. LC-MS/MS methods for the detection of intact and hydrolyzed carbapenems from an enrichment broth were developed. No ion suppression was observed, and the limits of detection for all three drugs were below 0.04 μg/ml. The sensitivity and specificity of meropenem and ertapenem for carbapenemase activity among non-Enterobacteriaceae were low, but imipenem demonstrated a sensitivity and specificity of 96% and 95%, respectively, among all Gram-negative rods (GNR) tested, including both Enterobacteriaceae and non-Enterobacteriaceae. LC-MS/MS allows for the analysis of more complex matrices, and this LC-MS/MS assay could easily be adapted for use with primary specimens requiring growth enrichment. PMID:24789180

High minimum inhibitory concentration of imipenem as a predictor of fatal outcome in patients with carbapenem non-susceptible Klebsiella pneumoniae.

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Wu, Ping-Feng; Chuang, Chien; Su, Chin-Fang; Lin, Yi-Tsung; Chan, Yu-Jiun; Wang, Fu-Der; Chuang, Yin-Ching; Siu, L Kristopher; Fung, Chang-Phone

2016-09-02

Carbapenem resistance in Klebsiella pneumoniae is important because of its increasing prevalence and limited therapeutic options. To investigate the clinical and microbiological characteristics of patients infected or colonized with carbapenem non-susceptible K. pneumoniae (CnsKP) in Taiwan, we conducted a retrospective study at Taipei Veterans General Hospital from January 2012 to November 2013. Carbapenem non-susceptibility was defined as a minimum inhibitory concentration (MIC) of ≥2 mg/L for imipenem or meropenem. A total of 105 cases with CnsKP were identified: 49 patients with infection and 56 patients with colonization. Thirty-one isolates had genes that encoded carbapenemases (29.5%), including K. pneumoniae carbapenemase (KPC)-2 (n = 27), KPC-3 (n = 1), VIM-1 (n = 1) and IMP-8 (n = 2). The in-hospital mortality among patients with CnsKP was 43.8%. A MIC for imipenem ≥16 μg/mL, nasogastric intubation and Acute Physiology and Chronic Health Evaluation II score were independent risk factors for in-hospital mortality for all patients with CnsKP. A MIC for imipenem ≥16 μg/mL was also an independent risk factor for 14-day mortality in patients with CnsKP. In conclusion, a positive culture for CnsKP was associated with high in-hospital mortality. A high imipenem MIC of CnsKP can predispose a patient to a poor prognosis.

The Soil Microbiota Harbors a Diversity of Carbapenem-Hydrolyzing β-Lactamases of Potential Clinical Relevance.

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Gudeta, Dereje Dadi; Bortolaia, Valeria; Amos, Greg; Wellington, Elizabeth M H; Brandt, Kristian K; Poirel, Laurent; Nielsen, Jesper Boye; Westh, Henrik; Guardabassi, Luca

2016-01-01

The origin of carbapenem-hydrolyzing metallo-β-lactamases (MBLs) acquired by clinical bacteria is largely unknown. We investigated the frequency, host range, diversity, and functionality of MBLs in the soil microbiota. Twenty-five soil samples of different types and geographical origins were analyzed by antimicrobial selective culture, followed by phenotypic testing and expression of MBL-encoding genes in Escherichia coli, and whole-genome sequencing of MBL-producing strains was performed. Carbapenemase activity was detected in 29 bacterial isolates from 13 soil samples, leading to identification of seven new MBLs in presumptive Pedobacter roseus (PEDO-1), Pedobacter borealis (PEDO-2), Pedobacter kyungheensis (PEDO-3), Chryseobacterium piscium (CPS-1), Epilithonimonas tenax (ESP-1), Massilia oculi (MSI-1), and Sphingomonas sp. (SPG-1). Carbapenemase production was likely an intrinsic feature in Chryseobacterium and Epilithonimonas, as it occurred in reference strains of different species within these genera. The amino acid identity to MBLs described in clinical bacteria ranged between 40 and 69%. Remarkable features of the new MBLs included prophage integration of the encoding gene (PEDO-1), an unusual amino acid residue at a key position for MBL structure and catalysis (CPS-1), and overlap with a putative OXA β-lactamase (MSI-1). Heterologous expression of PEDO-1, CPS-1, and ESP-1in E. coli significantly increased the MICs of ampicillin, ceftazidime, cefpodoxime, cefoxitin, and meropenem. Our study shows that MBL producers are widespread in soil and include four genera that were previously not known to produce MBLs. The MBLs produced by these bacteria are distantly related to MBLs identified in clinical samples but constitute resistance determinants of clinical relevance if acquired by pathogenic bacteria. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Potency of carbapenems for the prevention of carbapenem-resistant mutants of Pseudomonas aeruginosa: the high potency of a new carbapenem doripenem.

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Sakyo, Shihomi; Tomita, Haruyoshi; Tanimoto, Koichi; Fujimoto, Shuhei; Ike, Yasuyoshi

2006-04-01

The potencies of the carbapenems; doripenem (DRPM), meropenem (MEPM) and imipenem (IPM) in preventing the emergence of carbapenem-resistant mutants were examined in Pseudomonas aeruginosa strains. The carbapenems predominantly selected carbapenem-resistant mutants or carbapenem mutants with reduced susceptibilities that were specifically resistant to carbapenems and had arisen as a result of the reduced level of expression of the outer membrane protein with a molecular weight of about 48,000 (OprD). The potency of carbapenems in preventing the growth of the mutants differed for DRPM, MEPM and IPM. The isolation frequency of the mutant was examined on agar plates containing each of the carbapenems at a concentration of 1/2 or 1/4 MIC of each carbapenem for that mutant. Mutants were not selected on agar containing DRPM at a frequency of greater than 10(-9) per cell per generation, whereas mutants of each strain were selected on agar containing MEPM or IPM at frequencies of 10(-7) to 10(-9) per cell per generation. The drug concentrations and the drug concentration range for the selective increase of carbapenem resistant mutants in the broth culture containing each carbapenem differed for each carbapenem. DRPM exhibited both the lowest drug concentration and the narrowest range of drug concentration for selection of the carbapenem-resistant mutants. The results shown in this report indicated that DRPM exhibited the greatest ability to prevent the emergence of the mutant.

Characterization of the aroma of a meatlike process flavoring from soybean-based enzyme-hydrolyzed vegetable protein.

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Wu, Yi-Fang G; Cadwallader, Keith R

2002-05-08

Defatted soybean meal was converted into enzyme-hydrolyzed vegetable protein (E-HVP) using the proteolytic enzyme Flavorzyme. Total free amino acids increased by 40-fold after enzyme hydrolysis, with leucine being the most abundant, followed by phenylalanine, lysine, glutamine/glutamic acid, and alanine. Volatile components from a meatlike process flavoring made from E-HVP were isolated by direct solvent extraction (DSE)-high vacuum transfer (HVT), dynamic headspace sampling and static headspace sampling and analyzed by gas chromatography (GC)-mass spectrometry and GC-olfactometry. Aroma extract dilution analysis was used to establish a flavor dilution chromatogram of the DSE-HVT extract. Results of these complementary techniques indicated the importance of odorants of high (hydrogen sulfide and methanethiol), intermediate (2-methyl-3-furanthiol, 3-mercapto-2-pentanone, 2-furanmethanethiol, and 3-(methylthiol)propanal) and low volatility (maltol and Furaneol) in the overall aroma of the meatlike process flavoring.

Genomically Informed Surveillance for Carbapenem-Resistant Enterobacteriaceae in a Health Care System.

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Pecora, Nicole D; Li, Ning; Allard, Marc; Li, Cong; Albano, Esperanza; Delaney, Mary; Dubois, Andrea; Onderdonk, Andrew B; Bry, Lynn

2015-07-28

Carbapenem-resistant Enterobacteriaceae (CRE) are an urgent public health concern. Rapid identification of the resistance genes, their mobilization capacity, and strains carrying them is essential to direct hospital resources to prevent spread and improve patient outcomes. Whole-genome sequencing allows refined tracking of both chromosomal traits and associated mobile genetic elements that harbor resistance genes. To enhance surveillance of CREs, clinical isolates with phenotypic resistance to carbapenem antibiotics underwent whole-genome sequencing. Analysis of 41 isolates of Klebsiella pneumoniae and Enterobacter cloacae, collected over a 3-year period, identified K. pneumoniae carbapenemase (KPC) genes encoding KPC-2, -3, and -4 and OXA-48 carbapenemases. All occurred within transposons, including multiple Tn4401 transposon isoforms, embedded within more than 10 distinct plasmids representing incompatibility (Inc) groups IncR, -N, -A/C, -H, and -X. Using short-read sequencing, draft maps were generated of new KPC-carrying vectors, several of which were derivatives of the IncN plasmid pBK31551. Two strains also had Tn4401 chromosomal insertions. Integrated analyses of plasmid profiles and chromosomal single-nucleotide polymorphism (SNP) profiles refined the strain patterns and provided a baseline hospital mobilome to facilitate analysis of new isolates. When incorporated with patient epidemiological data, the findings identified limited outbreaks against a broader 3-year period of sporadic external entry of many different strains and resistance vectors into the hospital. These findings highlight the utility of genomic analyses in internal and external surveillance efforts to stem the transmission of drug-resistant strains within and across health care institutions. We demonstrate how detection of resistance genes within mobile elements and resistance-carrying strains furthers active surveillance efforts for drug resistance. Whole-genome sequencing is increasingly

Processing of poultry feathers by alkaline keratin hydrolyzing enzyme from Serratia sp. HPC 1383.

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Khardenavis, Anshuman A; Kapley, Atya; Purohit, Hemant J

2009-04-01

The present study describes the production and characterization of a feather hydrolyzing enzyme by Serratia sp. HPC 1383 isolated from tannery sludge, which was identified by the ability to form clear zones around colonies on milk agar plates. The proteolytic activity was expressed in terms of the micromoles of tyrosine released from substrate casein per ml per min (U/mL min). Induction of the inoculum with protein was essential to stimulate higher activity of the enzyme, with 0.03% feathermeal in the inoculum resulting in increased enzyme activity (45U/mL) that further increased to 90U/mL when 3d old inoculum was used. The highest enzyme activity, 130U/mL, was observed in the presence of 0.2% yeast extract. The optimum assay temperature and pH for the enzyme were found to be 60 degrees C and 10.0, respectively. The enzyme had a half-life of 10min at 60 degrees C, which improved slightly to 18min in presence of 1mM Ca(2+). Inhibition of the enzyme by phenylmethyl sulfonyl fluoride (PMSF) indicated that the enzyme was a serine protease. The enzyme was also partially inhibited (39%) by the reducing agent beta-mercaptoethanol and by divalent metal ions such as Zn(2+) (41% inhibition). However, Ca(2+) and Fe(2+) resulted in increases in enzyme activity of 15% and 26%, respectively. The kinetic constants of the keratinase were found to be 3.84 microM (K(m)) and 108.7 microM/mLmin (V(max)). These results suggest that this extracellular keratinase may be a useful alternative and eco-friendly route for handling the abundant amount of waste feathers or for applications in other industrial processes.

Characteristics of enzyme hydrolyzing natural covalent bond between RNA and protein VPg of encephalomyocarditis virus

International Nuclear Information System (INIS)

Drygin, Yu.F.; Siyanova, E.Yu.

1986-01-01

The isolation and a preliminary characterization of the enzyme specifically hydrolyzing the phosphodiester bond between protein VPg and the RNA of encephalomyocarditis virus was the goal of the present investigation. The enzyme was isolated from a salt extract of Krebs II mouse ascites carcinoma cells by ion-exchange and affinity chromatography. It was found that the enzyme actually specifically cleaves the covalent bond between the RNA and protein, however, the isolation procedure does not free the enzyme from impurities which partially inhibit it. The enzyme cleaves the RNA-protein VPg complex of polio virus at a high rate, it is completely inactivated at 55 0 C, and is partially inhibited by EDTA

Phenotypic and genotypic characteristics of carbapenem-resistant Enterobacteriaceae in a tertiary-level reference hospital in Turkey.

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Baran, Irmak; Aksu, Neriman

2016-04-06

Enterobacteriaceae are among the most common pathogens that are responsible for serious community-acquired, hospital-acquired, and health-care associated infections. The emergence and spread of carbapenem-resistant Enterobacteriaceae (CRE) have become an increasing concern for healthcare services worldwide. Infections caused by these bacteria have been associated with significant morbidity and mortality and treatment options have been limited. The rapid and accurate detection of carbapenem resistance in these bacteria is important for infection control. The aim of this study was to investigate the phenotypic and genotypic features of CRE strains isolated in a tertiary-level reference hospital in Turkey. A total of 181 CRE strains were included in the study. Antimicrobial susceptibility rates were tested using Vitek 2 system. Modified Hodge test (MHT) was performed using meropenem and ertapenem discs. Metallo-β-lactamase antimicrobial gradient test (E-test MBL strips) were used for evaluation of metallo-β-lactamase production. A multiplex PCR was used for detection of carbapenems resistance genes (IMP, VIM, KPC, NDM-1 and OXA-48). The OXA-48 gene was detected in 86 strains, NDM-1 gene in six strains, VIM gene in one strain. IMP and KPC genes were not identified. Three strains produced both OXA-48 and NDM-1 and one strain produced both OXA-48 and VIM. In two patients more than one genus of OXA-48 positive CREs was isolated. Ninety-two of the isolates were multidrug-resistant. One hundred and ten isolates were MHT with meropenem (MEM-MHT) positive and 109 isolates were MHT with ertapenem (ERT-MHT) positive. Nine of the isolates were positive with E-test MBL strips. The sensitivity of MEM-MHT and ERT-MHT for detection of OXA-48 was 70.9 and 70.6 %, respectively. MEM-MHT was found highly discriminative for OXA-48 Escherichia coli (p Enterobacteriaceae in the hospital environment. While OXA-48 is still the most common source of carbapenem resistance in

Amino acid residues that contribute to substrate specificity of class A beta-lactamase SME-1.

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Majiduddin, Fahd K; Palzkill, Timothy

2005-08-01

Carbapenem antibiotics are used as antibiotics of last resort because they possess a broad spectrum of antimicrobial activity and are not easily hydrolyzed by beta-lactamases. Recently, class A enzymes, such as the SME-1, NMC-A, and IMI-1 beta-lactamases, have been identified with the capacity to hydrolyze carbapenem antibiotics. Traditional class A beta-lactamases, such as TEM-1 and SHV-1, are unable to hydrolyze carbapenem antibiotics and exhibit some differences in sequence from those that are able to hydrolyze carbapenem antibiotics. The positions that differ may contribute to the unique substrate specificity of the class A carbapenemase SME-1. Codons in the SME-1 gene representing residues 104, 105, 132, 167, 237, and 241 were randomized by site-directed mutagenesis, and functional mutants were selected for the ability to hydrolyze imipenem, ampicillin, or cefotaxime. Although several positions are important for hydrolysis of beta-lactam antibiotics, no single position was found to uniquely contribute to carbapenem hydrolysis. The results of this study support a model whereby the carbapenemase activity of SME-1 is due to a highly distributed set of interactions that subtly alter the structure of the active-site pocket.

Amino Acid Residues That Contribute to Substrate Specificity of Class A β-Lactamase SME-1

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Majiduddin, Fahd K.; Palzkill, Timothy

2005-01-01

Carbapenem antibiotics are used as antibiotics of last resort because they possess a broad spectrum of antimicrobial activity and are not easily hydrolyzed by β-lactamases. Recently, class A enzymes, such as the SME-1, NMC-A, and IMI-1 β-lactamases, have been identified with the capacity to hydrolyze carbapenem antibiotics. Traditional class A β-lactamases, such as TEM-1 and SHV-1, are unable to hydrolyze carbapenem antibiotics and exhibit some differences in sequence from those that are able to hydrolyze carbapenem antibiotics. The positions that differ may contribute to the unique substrate specificity of the class A carbapenemase SME-1. Codons in the SME-1 gene representing residues 104, 105, 132, 167, 237, and 241 were randomized by site-directed mutagenesis, and functional mutants were selected for the ability to hydrolyze imipenem, ampicillin, or cefotaxime. Although several positions are important for hydrolysis of β-lactam antibiotics, no single position was found to uniquely contribute to carbapenem hydrolysis. The results of this study support a model whereby the carbapenemase activity of SME-1 is due to a highly distributed set of interactions that subtly alter the structure of the active-site pocket. PMID:16048956

Molecular epidemiology of carbapenem resistant gram-negative bacilli from infected pediatric population in tertiary - care hospitals in Medellín, Colombia: an increasing problem.

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Vanegas, Johanna M; Parra, O Lorena; Jiménez, J Natalia

2016-09-01

Gram-negative bacilli are a cause of serious infections in the pediatric population. Carbapenem are the treatment of choice for infections caused by multidrug-resistant Gram-negative bacilli, but the emergence of carbapenem resistance has substantially reduced access to effective antimicrobial regimens. Children are a population vulnerable to bacterial infections and the emergence of resistance can worsen prognosis. The aim of this study is to describe the clinical and molecular characteristics of infections caused by carbapenem-resistant Gram-negative bacilli in pediatric patients from five tertiary-care hospitals in Medellín, Colombia. A cross-sectional study was conducted in five tertiary-care hospitals from June 2012 to June 2014. All pediatric patients infected by carbapenem-resistant Gram-negative bacilli were included. Clinical information for each patient was obtained from medical records. Molecular analyses included PCR for detection of bla VIM, bla IMP bla NDM, bla OXA-48 and bla KPC genes and PFGE and MLST for molecular typing. A total of 59 patients were enrolled, most of them less than 1 year old (40.7 % n = 24), with a previous history of antibiotic use (94.9 %; n = 56) and healthcare-associated infections - predominately urinary tract infections (31.0 %; n = 18). Klebsiella pneumoniae was the most frequent bacteria (47.4 %), followed by Enterobacter cloacae (40.7 %) and Pseudomonas aeruginosa (11.9 %). For K. pneumoniae, KPC was the predominant resistance mechanism (85.7 %; n = 24) and ST14 was the most common clone (39.3 % n = 11), which included strains closely related by PFGE. In contrast, E. cloacae and P. aeruginosa were prevailing non-carbapenemase-producing isolates (only KPC and VIM were detected in 1 and 3 isolates, respectively) and high genetic diversity according to PFGE and MLST was found in the majority of the cases. In recent years, increasing carbapenem-resistant bacilli in children has become in a matter

mcr-1 and blaKPC-3 in Escherichia coli Sequence Type 744 after Meropenem and Colistin Therapy, Portugal.

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Tacão, Marta; Tavares, Rafael Dos Santos; Teixeira, Pedro; Roxo, Inês; Ramalheira, Elmano; Ferreira, Sónia; Henriques, Isabel

2017-08-01

Escherichia coli Ec36 was recovered from a patient in Portugal after treatment with meropenem and colistin. Besides an IncF plasmid with Tn1441d-bla KPC-3 , already reported in clinical strains in this country, E. coli Ec36 co-harbored an IncX4::mcr-1 gene. Results highlight emerging co-resistance to carbapenems and polymyxins after therapy with drugs from both classes.

Effect of temperature and mixing speed on immobilization of crude enzyme from Aspergillus niger on chitosan for hydrolyzing cellulose

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Hamzah, Afan; Gek Ela Kumala, P.; Ramadhani, Dwi; Maziyah, Nurul; Rahmah, Laila Nur; Soeprijanto, Widjaja, Arief

2017-05-01

Conversion of cellulose into reducing sugar through enzymatic hydrolysis has advantageous because it produces greater product yield, higher selectivity, require less energy, more moderate operating conditions and environment friendly. However, the nature of the enzyme that is difficult to separate and its expensive price become an obstacle. These obstacles can be overcome by immobilizing the enzyme on chitosan material so that the enzyme can be reused. Chitosan is chosen because it is cheap, inert, hydrophilic, and biocompatible. In this research, we use covalent attachment and combination between covalent attachment and cross-linking method for immobilizing crude enzyme. This research was focusing in study of Effect of temperature and mixing speed on Immobilization Enzyme From Aspergillus Niger on Chitosan For Hydrolyzing both soluble (Carboxymethylcellulose) and insoluble Cellulose (coconut husk). This Research was carried out by three main step. First, coconut husk was pre-treated mechanically and chemically, Second, Crude enzyme from Aspergillus niger strain was immobilized on chitosan in various immobilization condition. At last, the pre-treated coconut husk and Carboxymetylcellulose (CMC) were hydrolyzed by immobilized cellulose on chitosan for reducing sugar production. The result revealed that the most reducing sugar produced by immobilized enzyme on chitosan+GDA with immobilization condition at 30 °C and 125 rpm. Enzyme immobilized on chitosan cross-linked with GDA produced more reducing sugar from preteated coconut husk than enzyme immobilized on chitosan.

Outbreak by Hypermucoviscous Klebsiella pneumoniae ST11 Isolates with Carbapenem Resistance in a Tertiary Hospital in China

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Lingling Zhan

2017-05-01

Full Text Available Hypervirulent and multidrug resistant Klebsiella pneumoniae strains pose a significant threat to the public health. In the present study, 21 carbapenem-resistant K. pneumoniae isolates (CRKP were determined by the string test as hypermucoviscous K. pneumoniae (HMKP, with the prevalence of 15.0% (21/140 among CRKP, and 1.1% (21/1838 among all K. pneumoniae isolates. Among them, 7 (33.3%, and 1 (4.76% isolate belonged to capsular serotype K20 and K2 respectively, while 13 (61.9%, 13/21 weren't successfully typed by capsular serotyping. All the 21 isolates were carbapenemase-producers and were positive for blaKPC-2. In addition to blaKPC-2, all the 21 isolates except one harbor blaSHV-11, and 15 carry extended-spectrum β-lactamase gene blaCTX-M-65. The virulence-associated genes with more than 90% of positive rates among 21 isolates included ureA (100%, 21/21, wabG (100%, 21/21, fimH (95.2%, 20/21, entB (95.2%, 20/21, ycf (95.2%, 20/21, ybtS (95.2%, 20/21, and iutA (90.5%, 19/21. rmpA and aerobactin were found in 57.1% (12/21 isolates. Five sequence types (STs were identified by multilocus sequence typing (MLST, including ST11 (11 K-non capsule typable and 5 K20 isolates, ST268 (1 K20 isolate and 1 K-non capsule typable isolate, ST65 (1 K2 isolate, ST692 (1 K-non capsule typable isolate, and ST595, a novel sequence type (1 K-non capsule typable isolate. Pulsed-field gel electrophoresis (PFGE results showed two major PFGE clusters, of which cluster A accounts for 6 ST11 isolates (28.6% and cluster B includes 8 ST11 isolates (38.1%, 8/21. Ten and six ST11 isolates were isolated from 2014 and 2015, respectively, while 8 were isolated from the same month of December in 2014. Ten isolates were collected from the intensive care unit (ICU, and all except one belonged to ST11. Additional 4 ST11 isolates were collected from patients in non-ICU wards, who had more than 10 days of ICU stay history in 2014 prior to transfer to their current wards where the

Recent advances in the chemistry and biology of carbapenem antibiotics.

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Coulton, S; Hunt, E

1996-01-01

The discovery of the olivanic acids and thienamycin aroused considerable interest amongst medicinal chemists and microbiologists around the world. The susceptibility of these agents to metabolic degradation has, however, been a major obstacle in their development. For many years the only notable success from such intensive research was the combination of imipenem with cilastatin, an inhibitor of the renal dipeptidase enzyme DHP-1. The enormous success of Primaxin for the treatment of a range of life-threatening bacterial infections provided the impetus for the discovery of totally synthetic, non-natural carbapenem derivatives that combine the broad spectrum of antimicrobial activity with stability to enzymatic degradation. This has indeed been realised in the development of meropenem; it possesses the broad spectrum of activity and resistance to beta-lactamases that are embodied in imipenem as well as displaying increased stability to human dehydropeptidases. Most recent research has focused upon the development of carbapenem antibiotics which combine broad spectrum antimicrobial activity and metabolic stability with oral absorption, for the treatment of community-acquired infections. Indeed, the pro-drug esters of the tricyclic carbapenems represent the first significant advance in this respect. However, the increased use of carbapenem antibiotics would undoubtedly accelerate the emergence of carbapenem-hydrolysing enzymes. The ultimate challenge could therefore be the design and synthesis of carbapenem derivatives that are resistant to these metallo-beta-lactamases. Due to the enormous problems encountered in the development of the carbapenem antibiotics, this area of research has, in the past, been described as a battlefield that did not bode well for the future [181]. Primaxin and meropenem proved however that these problems were not insurmountable, and are therefore a testimony to the persistence and dedication of those scientists in their war against

Carbapenem non-susceptible enterobacteriaceae in Quebec, Canada: results of a laboratory surveillance program (2010-2012.

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Brigitte Lefebvre

Full Text Available The emergence and spread of carbapenemase-producing Enterobacteriaceae (CPE represent a major public health concern because these bacteria are usually extensively resistant to most antibiotics. In order to evaluate their dissemination in Quebec, a surveillance program was introduced in 2010. We report the molecular and epidemiological profiles of CPE isolates collected. Between August 2010 and December 2012, a total of 742 non-duplicate isolates non-susceptible to carbapenems were analysed. AmpC β-lactamase and metallo-β-lactamase production were detected by Etest and carbapenemase production by the modified Hodge test (MHT. Antibiotic susceptibility profiles were determined using broth microdilution or Etest. Clonality of Klebsiella pneumoniae carbapenemase (KPC strains was analyzed by pulsed-field gel electrophoresis (PFGE. The presence of genes encoding carbapenemases as well as other β-lactamases was detected using PCR. Of the 742 isolates tested, 169 (22.8% were CPE. Of these 169 isolates, 151 (89.3% harboured a blaKPC gene while the remaining isolates carried blaSME (n = 9, blaOXA-48 (n = 5, blaNDM (n = 3, and blaNMC (n = 1 genes. Among the 93 KPC strains presenting with a unique pattern (unique PFGE pattern and/or unique antibiotics susceptibility profile, 99% were resistant to ertapenem, 95% to imipenem, 87% to meropenem, 97% to aztreonam, 31% to colistin and 2% to tigecycline. In 19 patients, 2 to 5 KPC strains from different species or with a different PFGE pattern were isolated. CPE strains were present in the province of Quebec with the majority of strains harbouring KPC. Alternately, SME, OXA-48 and NMC containing strains were rarely found.

Antimicrobial activity evaluation and comparison of methods of susceptibility for Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacter spp. isolates.

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Rechenchoski, Daniele Zendrini; Dambrozio, Angélica Marim Lopes; Vivan, Ana Carolina Polano; Schuroff, Paulo Alfonso; Burgos, Tatiane das Neves; Pelisson, Marsileni; Perugini, Marcia Regina Eches; Vespero, Eliana Carolina

The production of KPC (Klebsiella pneumoniae carbapenemase) is the major mechanism of resistance to carbapenem agents in enterobacterias. In this context, forty KPC-producing Enterobacter spp. clinical isolates were studied. It was evaluated the activity of antimicrobial agents: polymyxin B, tigecycline, ertapenem, imipenem and meropenem, and was performed a comparison of the methodologies used to determine the susceptibility: broth microdilution, Etest ® (bioMérieux), Vitek 2 ® automated system (bioMérieux) and disc diffusion. It was calculated the minimum inhibitory concentration (MIC) for each antimicrobial and polymyxin B showed the lowest concentrations for broth microdilution. Errors also were calculated among the techniques, tigecycline and ertapenem were the antibiotics with the largest and the lower number of discrepancies, respectively. Moreover, Vitek 2 ® automated system was the method most similar compared to the broth microdilution. Therefore, is important to evaluate the performance of new methods in comparison to the reference method, broth microdilution. Copyright © 2017 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

A Rapid Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry-Based Method for Single-Plasmid Tracking in an Outbreak of Carbapenem-Resistant Enterobacteriaceae

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Lau, Anna F.; Wang, Honghui; Weingarten, Rebecca A.; Drake, Steven K.; Suffredini, Anthony F.; Garfield, Mark K.; Chen, Yong; Gucek, Marjan; Youn, Jung-Ho; Stock, Frida; Tso, Hanna; DeLeo, Jim; Cimino, James J.; Frank, Karen M.

2014-01-01

Carbapenem-resistant Enterobacteriaceae (CRE) have spread globally and represent a serious and growing threat to public health. Rapid methods for tracking plasmids carrying carbapenemase genes could greatly benefit infection control efforts. Here, we demonstrate that real-time, direct tracking of a single plasmid in a bacterial strain responsible for an outbreak is possible using a commercial matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) system. In this case, we retrospectively tracked the blaKPC carbapenemase gene-bearing pKpQIL plasmid responsible for a CRE outbreak that occurred at the NIH Clinical Center in 2011. An ∼11,109-Da MS peak corresponding to a gene product of the blaKPC pKpQIL plasmid was identified and characterized using a combination of proteomics and molecular techniques. This plasmid peak was present in spectra from retrospectively analyzed K. pneumoniae outbreak isolates, concordant with results from whole-genome sequencing, and absent from a diverse control set of blaKPC-negative clinical Enterobacteriaceae isolates. Notably, the gene characterized here is located adjacent to the blaKPC Tn4401 transposon on the pKpQIL plasmid. Sequence analysis demonstrates the presence of this gene in other blaKPC Tn4401-containing plasmids and suggests that this signature MS peak may be useful in tracking other plasmids conferring carbapenem resistance. Plasmid identification using this MALDI-TOF MS method was accomplished in as little as 10 min from isolated colonies and 30 min from positive (spiked) blood cultures, demonstrating the potential clinical utility for real-time plasmid tracking in an outbreak. PMID:24850353

The outcome of treating ESBL infections with carbapenems vs. non carbapenem antimicrobials.

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Trivedi, Mayuri; Trivedi, Mayur; Patel, Vipul; Soman, Rajeev; Rodriguez, Camilla; Singhal, Tanu

2012-08-01

In India where the prevalence of extended spectrum beta lactamase (ESBL) producing organisms among gram negative organisms is 60-70% and Ertapenem was unavailable at the beginning of this study, exclusive use of Group 2 Carbapenems (Imipenem and Meropenem) for treatment raises issues of cost and development of resistance. Therefore the role of non-Carbapenem alternatives, chiefly Betalactam + Betalactamase inhibitors (BL-BLI) was explored in this prospective observational study at a private tertiary care teaching hospital. 522 consecutive in door patients from the period between June 2006 to March 2007and June 2008 to December 2008, who had true infections with ESBL producing organisms were enrolled in the study. Antimicrobials were prescribed or changed by the treating physicians on the basis of the nature and severity of infection, the susceptibility of the organism and the affordability of the patient. Patients who received a Carbapenem at any time during treatment were considered in the Carbapenem group. Those who never received a Carbapenem at any time during treatment were considered in the non-Carbapenem group. Of the 522 infections, 287 were urinary tract infections, 60 were skin structure infections, 60 were bacteremias, 55 were hospital acquired pneumonias, 31 were intra-abdominal infections and 29 were other infections. There were 351 E. coli, 119 K. pneumoniae, 23 K. oxytoca, 16 Enterobacter aerogenes, 5 Kozoanae, 4 Enterobacter agglomerans, 3 Citrobacter freundi, 1 E. cloacae, 1 Enterobacterspp. and 1 Morgenella morganii isolates. Clinical outcomes were available for 486 patients. 339 patients who were in the non-Carbapenem group and who might have had less serious infections had a clinical success rate of 79.6%. 147 patients who were in the Carbapenem group and who might have had more serious infections had a clinical success rate of 85.71%. It is possible to successfully treat at least the less serious infections due to ESBL producing gram negative

In vitro inhibition activity of polyphenol-rich extracts from Syzygium aromaticum (L.) Merr. & Perry (Clove) buds against carbohydrate hydrolyzing enzymes linked to type 2 diabetes and Fe(2+)-induced lipid peroxidation in rat pancreas.

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Adefegha, Stephen Adeniyi; Oboh, Ganiyu

2012-10-01

To investigate and compare the inhibitory properties of free and bound phenolic extracts of clove bud against carbohydrate hydrolyzing enzymes (alpha-amylase & alpha-glucosidase) and Fe(2+)-induced lipid peroxidation in rat pancreas in vitro. The free phenolics were extracted with 80% (v/v) acetone, while bound phenolics were extracted from the alkaline and acid hydrolyzed residue with ethyl acetate. Then, the interaction of the extracts with alpha-amylase and alpha-glucosidase was subsequently assessed. Thereafter, the total phenolic contents and antioxidant activities of the extracts were determined. The result revealed that both extracts inhibited alpha-amylase and alpha-glucosidase in a dose-dependent manner. However, the alpha-glucosidase inhibitory activity of the extracts were significantly (Ppancreas in vitro. This study provides a biochemical rationale by which clove elicits therapeutic effect on type 2 diabetes.

Effect of 60Co γ-rays irradiation on rice straw fibre structure and enzyme hydrolyzation

International Nuclear Information System (INIS)

Chen Jingping; Li Wenge; Peng Ling; Wang Keqin; Xiong Xingyao

2008-01-01

The effect of improving enzyme hydrolyze of rice straw was estimated with treating dry rice straw and raw fiber by 60 Co γ-rays irradiation. the water-soluble deoxidize carbohydrate and total carbohydrate of 60 Co γ-rays irradiated rice straw and raw fibres were measured by DNS method and vitrol-phenol method. The changes of deoxidize carbohydrate groups of irradiated hydrolyzing rice straw were analyzed by gas chromatography. The organism structures of irradiated rice straw were scanned by electron microscope, the results showed that 1000-1500 kGy 60 Co γ-irradiation doses effectively destroyed rice straw's organism structures, especially the silicon crystal structures, and along with irradiation doses increased the breakage degree enlarged significantly. The contents of the water-soluble deoxidize carbohydrate and total carbohydrate of rice straw increased significantly. treated by both irradiation and enzyme, the cellulose transform rate of rice straw was 88.7%, which is better than that only treated by 60 Co γ-irradiation or enzyme. The content of water-solubility deoxidize carbohydrate of the treated rice straw was 214.4 mg/g and the total carbohydrate of straw was 758.5 mg/g. The contents of mannose, galactose, glucose, arabinose and xylose increased significantly, among those carbohydrate, the glucose's increment was the largest and account for 62.64%, and mannose's increments was the second. The contents of lignin of the rice straw were not influenced obviously by irradiation treatment. (authors)

Efficient dark fermentative hydrogen production from enzyme hydrolyzed rice straw by Clostridium pasteurianum (MTCC116).

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Srivastava, Neha; Srivastava, Manish; Kushwaha, Deepika; Gupta, Vijai Kumar; Manikanta, Ambepu; Ramteke, P W; Mishra, P K

2017-08-01

In the present work, production of hydrogen via dark fermentation has been carried out using the hydrolyzed rice straw and Clostridium pasteurianum (MTCC116). The hydrolysis reaction of 1.0% alkali pretreated rice straw was performed at 70°C and 10% substrate loading via Fe 3 O 4 /Alginate nanocomposite (Fe 3 O 4 /Alginate NCs) treated thermostable crude cellulase enzyme following the previously established method. It is noticed that under the optimized conditions, at 70°C the Fe 3 O 4 /Alginate NCs treated cellulase has produced around 54.18g/L sugars as the rice straw hydrolyzate. Moreover, the efficiency of the process illustrates that using this hydrolyzate, Clostridium pasteurianum (MTCC116) could produce cumulative hydrogen of 2580ml/L in 144h with the maximum production rate of 23.96ml/L/h in 96h. In addition, maximum dry bacterial biomass of 1.02g/L and 1.51g/L was recorded after 96h and 144h, respectively with corresponding initial pH of 6.6 and 3.8, suggesting higher hydrogen production. Copyright © 2017 Elsevier Ltd. All rights reserved.

Spectrophotometry-based detection of carbapenemase producers among Enterobacteriaceae.

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Bernabeu, Sandrine; Poirel, Laurent; Nordmann, Patrice

2012-09-01

Carbapenem-hydrolyzing ß-lactamases are the most powerful ß-lactamases being able to hydrolyse almost all ß-lactams. They are mostly of the KPC, VIM, IMP, NDM, and OXA-48 type. A spectrophotometry technique based on analysis of the imipenem hydrolysis has been developed that differentiated carbapenemase- from noncarbapenemase producers. This inexpensive technique adapted to screening of carbapenemase producers may be implemented in any reference laboratory worldwide. Copyright © 2012 Elsevier Inc. All rights reserved.

The Carbapenem Inactivation Method (CIM), a Simple and Low-Cost Alternative for the Carba NP Test to Assess Phenotypic Carbapenemase Activity in Gram-Negative Rods

NARCIS (Netherlands)

Zwaluw, K. van der; Haan, A. de; Pluister, G.N.; Bootsma, H.J.; Neeling, A.J. de; Schouls, L.M.

2015-01-01

A new phenotypic test, called the Carbapenem Inactivation Method (CIM), was developed to detect carbapenemase activity in Gram-negative rods within eight hours. This method showed high concordance with results obtained by PCR to detect genes coding for the carbapenemases KPC, NDM, OXA-48, VIM, IMP

Plant cell-wall hydrolyzing enzymes from indigenously isolated fungi grown on conventional and novel natural substrates

International Nuclear Information System (INIS)

Kumari, D.; Sohail, M.; Jahangeer, S.; Abideen, Z.; Khan, M.A.

2017-01-01

Fungi elaborate a variety of plant-hydrolyzing enzymes including cellulases, xylanases, pectinases and amylases. Although these enzymes have potential biotechnological applications, their production at industrial level is limited because of higher costs of the purified substrates. Hence, the present study was aimed to explore the novel, natural and cheaper substrates for enzyme production. Indigenously isolated fungal strains of Aspergillus sp. were grown on banana-peels, grapefruit-peels, pomegranate-peels, sugarcane bagasse, Eucalyptus camaldulensis-leaves and shoots of two halophytic plants including Halopyrum mucronatum and Desmostachya bipinnata under solid-state fermentation (SSF) and submerged fermentation (Smf) conditions. The crude enzyme preparation was screened for cellulase (endoglucanase, beta-glucosidase and filter-paperase), hemicellulase (xylanase), pectinase and amylase production. The results revealed that among all investigated enzymes, the xylanase titers were highest using D. bipinnata- shoots and H. mucronatum- shoots as substrates under solid state fermentation conditions, suggesting their exploitation at commercial scale. (author)

Virulence of Klebsiella pneumoniae isolates harboring bla KPC-2 carbapenemase gene in a Caenorhabditis elegans model.

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Jean-Philippe Lavigne

Full Text Available Klebsiella pneumoniae carbapenemase (KPC is a carbapenemase increasingly reported worldwide in Enterobacteriaceae. The aim of this study was to analyze the virulence of several KPC-2-producing K. pneumoniae isolates. The studied strains were (i five KPC-2 clinical strains from different geographical origins, belonging to different ST-types and possessing plasmids of different incompatibility groups; (ii seven transformants obtained after electroporation of either these natural KPC plasmids or a recombinant plasmid harboring only the bla KPC-2 gene into reference strains K. pneumoniae ATCC10031/CIP53153; and (iii five clinical strains cured of plasmids. The virulence of K. pneumoniae isolates was evaluated in the Caenorhabditis elegans model. The clinical KPC producers and transformants were significantly less virulent (LT50: 5.5 days than K. pneumoniae reference strain (LT50: 4.3 days (p<0.01. However, the worldwide spread KPC-2 positive K. pneumoniae ST258 strains and reference strains containing plasmids extracted from K. pneumoniae ST258 strains had a higher virulence than KPC-2 strains belonging to other ST types (LT50: 5 days vs. 6 days, p<0.01. The increased virulence observed in cured strains confirmed this trend. The bla KPC-2 gene itself was not associated to increased virulence.

A rapid matrix-assisted laser desorption ionization-time of flight mass spectrometry-based method for single-plasmid tracking in an outbreak of carbapenem-resistant Enterobacteriaceae.

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Lau, Anna F; Wang, Honghui; Weingarten, Rebecca A; Drake, Steven K; Suffredini, Anthony F; Garfield, Mark K; Chen, Yong; Gucek, Marjan; Youn, Jung-Ho; Stock, Frida; Tso, Hanna; DeLeo, Jim; Cimino, James J; Frank, Karen M; Dekker, John P

2014-08-01

Carbapenem-resistant Enterobacteriaceae (CRE) have spread globally and represent a serious and growing threat to public health. Rapid methods for tracking plasmids carrying carbapenemase genes could greatly benefit infection control efforts. Here, we demonstrate that real-time, direct tracking of a single plasmid in a bacterial strain responsible for an outbreak is possible using a commercial matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system. In this case, we retrospectively tracked the bla(KPC) carbapenemase gene-bearing pKpQIL plasmid responsible for a CRE outbreak that occurred at the NIH Clinical Center in 2011. An ∼ 11,109-Da MS peak corresponding to a gene product of the bla(KPC) pKpQIL plasmid was identified and characterized using a combination of proteomics and molecular techniques. This plasmid peak was present in spectra from retrospectively analyzed K. pneumoniae outbreak isolates, concordant with results from whole-genome sequencing, and absent from a diverse control set of bla(KPC)-negative clinical Enterobacteriaceae isolates. Notably, the gene characterized here is located adjacent to the bla(KPC) Tn4401 transposon on the pKpQIL plasmid. Sequence analysis demonstrates the presence of this gene in other bla(KPC) Tn4401-containing plasmids and suggests that this signature MS peak may be useful in tracking other plasmids conferring carbapenem resistance. Plasmid identification using this MALDI-TOF MS method was accomplished in as little as 10 min from isolated colonies and 30 min from positive (spiked) blood cultures, demonstrating the potential clinical utility for real-time plasmid tracking in an outbreak. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Definition of the Common and Divergent Steps in Carbapenem β-Lactam Antibiotic Biosynthesis

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Bodner, Micah J.; Li, Rongfeng; Phelan, Ryan M.; Freeman, Michael F.; Moshos, Kristos A.; Lloyd, Evan P.

2012-01-01

Approximately 50 naturally occurring carbapenem β-lactam antibiotics are known. All but one of these have been isolated from Streptomyces species and are disubstituted structural variants of a simple core that is synthesized by Pectobacterium carotovorum (Erwinia carotovora), a phylogenetically distant plant pathogen. While the biosynthesis of the simple carbapenem, (5R)-carbapen-2-em-3-carboxylic acid, is impressively efficient requiring only three enzymes, CarA, CarB and CarC, the formation of thienamycin, one of the former group of metabolites from Streptomyces, is markedly more complex. Despite their phylogenetic separation, bioinformatic analysis of the encoding gene clusters suggests that the two pathways could be related. Here we demonstrate with gene swapping, stereochemical and kinetics experiments that CarB and CarA and their S. cattleya orthologues, ThnE and ThnM, respectively, are functionally and stereochemically equivalent, although their catalytic efficiencies differ. The biosynthetic pathways, therefore, to thienamycin, and likely to the other disubstituted carbapenems, and to the simplest carbapenem, (5R)-carbapen-2-em-3-carboxylic acid, are initiated in the same manner, but share only two common steps before diverging. PMID:21913298

Performance evaluation of three automated identification systems in detecting carbapenem-resistant Enterobacteriaceae.

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He, Qingwen; Chen, Weiyuan; Huang, Liya; Lin, Qili; Zhang, Jingling; Liu, Rui; Li, Bin

2016-06-21

Carbapenem-resistant Enterobacteriaceae (CRE) is prevalent around the world. Rapid and accurate detection of CRE is urgently needed to provide effective treatment. Automated identification systems have been widely used in clinical microbiology laboratories for rapid and high-efficient identification of pathogenic bacteria. However, critical evaluation and comparison are needed to determine the specificity and accuracy of different systems. The aim of this study was to evaluate the performance of three commonly used automated identification systems on the detection of CRE. A total of 81 non-repetitive clinical CRE isolates were collected from August 2011 to August 2012 in a Chinese university hospital, and all the isolates were confirmed to be resistant to carbapenems by the agar dilution method. The potential presence of carbapenemase genotypes of the 81 isolates was detected by PCR and sequencing. Using 81 clinical CRE isolates, we evaluated and compared the performance of three automated identification systems, MicroScan WalkAway 96 Plus, Phoenix 100, and Vitek 2 Compact, which are commonly used in China. To identify CRE, the comparator methodology was agar dilution method, while the PCR and sequencing was the comparator one to identify CPE. PCR and sequencing analysis showed that 48 of the 81 CRE isolates carried carbapenemase genes, including 23 (28.4 %) IMP-4, 14 (17.3 %) IMP-8, 5 (6.2 %) NDM-1, and 8 (9.9 %) KPC-2. Notably, one Klebsiella pneumoniae isolate produced both IMP-4 and NDM-1. One Klebsiella oxytoca isolate produced both KPC-2 and IMP-8. Of the 81 clinical CRE isolates, 56 (69.1 %), 33 (40.7 %) and 77 (95.1 %) were identified as CRE by MicroScan WalkAway 96 Plus, Phoenix 100, and Vitek 2 Compact, respectively. The sensitivities/specificities of MicroScan WalkAway, Phoenix 100 and Vitek 2 were 93.8/42.4 %, 54.2/66.7 %, and 75.0/36.4 %, respectively. The MicroScan WalkAway and Viteck2 systems are more reliable in clinical identification of

Purification and Characterization of a Ginsenoside Rb1-Hydrolyzing β-Glucosidase from Aspergillus niger KCCM 11239

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Kyung Hoon Chang

2012-09-01

Full Text Available Rb1-hydrolyzing β-glucosidase from Aspergillus niger KCCM 11239 was studied to develop a bioconversion process for minor ginsenosides. The specific activity of the purified enzyme was 46.5 times greater than that of the crude enzyme. The molecular weight of the native enzyme was estimated to be approximately 123 kDa. The optimal pH of the purified enzyme was pH 4.0, and the enzyme proved highly stable over a pH range of 5.0–10.0. The optimal temperature was 70 °C, and the enzyme became unstable at temperatures above 60 °C. The enzyme was inhibited by Cu2+, Mg2+, Co2+, and acetic acid (10 mM. In the specificity tests, the enzyme was found to be active against ginsenoside Rb1, but showed very low levels of activity against Rb2, Rc, Rd, Re, and Rg1. The enzyme hydrolyzed the 20-C,β-(1→6-glucoside of ginsenoside Rb1 to generate ginsenoside Rd and Rg3, and hydrolyzed 3-C,β-(1→2-glucoside to generate F2. The properties of the enzyme indicate that it could be a useful tool in biotransformation applications in the ginseng industry, as well as in the development of novel drug compounds.

Act Fast as Time Is Less: High Faecal Carriage of Carbapenem-Resistant Enterobacteriaceae in Critical Care Patients.

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Saseedharan, Sanjith; Sahu, Manisa; Pathrose, Edwin Joseph; Shivdas, Sarita

2016-09-01

Carbapenem-resistant Enterobacteriaceae (CRE) are drug-resistant Gram-negative bacteria that are present in the community as well as in hospitals. Their infection and colonisation puts critically ill patients at high risk due to the drug-resistant nature of the strains and possible spreading of these organisms, even in a hospital environment. To examine the presence and types of Enterobacteriaceae species in patients admitted directly from the community. The present study was a one-month pilot conducted in the ICU of a tertiary care hospital in Mumbai, India in 2015. Faecal samples of patients admitted from the community directly to the ICU were analysed using tests like MHT (Modified Hodge) and EDTA for the presence of IMP (action on Imipenem) and KPC ( Klebsiella Test Pneumoniae Carbapenemase) producing strains of Enterobacteriaceae . Polymerase Chain Reaction (PCR) was performed to look for VIM , IMP , NDM 1, OXA , and KPC genes. Antibiotic Sensitivity Test was carried out as per CLSI guidelines. The results showed an alarming level of faecal carriage rates in adult ICU patients. Klebsiella pneumonia was the most common carbapenem-resistant isolate, closely followed by Escherichia coli . PCR results revealed nine strains were positive for bla (KPC) gene, from which 7 were Klebsiella pneumoniae and one each of Escherichia coli and Klebsiella oxytoca was observed. Antibiotic Sensitivity Test results showed that the isolates had maximum sensitivity to Colistin (100%) and Tigecycline (95%). These levels indicate that in the absence of CRE screenings, proper isolation of carrier patients is not possible, leading to possible spreading of these resistant bacteria strains in ICUs. A longer period of study is required to obtain more substantial data to validate the results of this pilot.

Comparative pharmacodynamics of four different carbapenems in combination with polymyxin B against carbapenem-resistant Acinetobacter baumannii.

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Lenhard, Justin R; Gall, Jonathan S; Bulitta, Jurgen B; Thamlikitkul, Visanu; Landersdorfer, Cornelia B; Forrest, Alan; Nation, Roger L; Li, Jian; Tsuji, Brian T

2016-12-01

The objective of this study was to determine the comparative pharmacodynamics of four different carbapenems in combination with polymyxin B (PMB) against carbapenem-resistant Acinetobacter baumannii isolates using time-kill experiments at two different inocula. Two A. baumannii strains (03-149-1 and N16870) with carbapenem minimum inhibitory concentrations (MICs) ranging from 8 to 64 mg/L were investigated in 48-h time-kill experiments using starting inocula of 10 6  CFU/mL and 10 8  CFU/mL. Concentration arrays of ertapenem, doripenem, meropenem and imipenem at 0.25×, 0.5×, 1×, 1.5× and 2× published maximum serum concentration (C max ) values (C max concentrations of 12, 21, 48 and 60 mg/L, respectively) were investigated in the presence of 1.5 mg/L PMB. Use of carbapenems without PMB resulted in drastic re-growth. All carbapenem combinations were able to achieve a ≥3 log 10 CFU/mL reduction by 4 h against both strains at 10 6  CFU/mL, whereas maximum reductions against strain 03-149-1 at 10 8  CFU/mL were 1.0, 3.2, 2.2 and 3.3 log 10 CFU/mL for ertapenem, doripenem, meropenem and imipenem, respectively. None of the combinations were capable of reducing 10 8  CFU/mL of N16870 by ≥2 log 10 CFU/mL. Ertapenem combinations consistently displayed the least activity, whereas doripenem, meropenem and imipenem combinations had similar activities that were poorly predicted by carbapenem MICs. As doripenem, meropenem, or imipenem displayed similar pharmacodyanmics in combination, the decision of which carbapenem to use in combination with PMB may be based on toxicodynamic profiles if drastic discordance in MICs is not present. Copyright © 2016. Published by Elsevier B.V.

Activity of Simulated Human Dosage Regimens of Meropenem and Vaborbactam against Carbapenem-Resistant Enterobacteriaceae in an In Vitro Hollow-Fiber Model.

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Sabet, Mojgan; Tarazi, Ziad; Rubio-Aparicio, Debora; Nolan, Thomas G; Parkinson, Jonathan; Lomovskaya, Olga; Dudley, Michael N; Griffith, David C

2018-02-01

The objective of these studies was to evaluate the exposures of meropenem and vaborbactam that would produce antibacterial activity and prevent resistance development in carbapenem-resistant Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae strains when tested at an inoculum of 10 8 CFU/ml. Thirteen K. pneumoniae isolates, three Enterobacter cloacae isolates, and one Escherichia coli isolate were examined in an in vitro hollow-fiber model over 32 h. Simulated dosage regimens of 1 to 2 g of meropenem with 1 to 2 g of vaborbactam, with meropenem administered every 8 h by a 3-h infusion based on phase 1 or phase 3 patient pharmacokinetic data, were studied in the model. A dosage of 2 g of meropenem in combination with 2 g of vaborbactam was bactericidal against K. pneumoniae , E. cloacae , and E. coli strains, with meropenem-vaborbactam MICs of up to 8 mg/liter. When the vaborbactam exposure was adjusted to the levels observed in patients enrolled in phase 3 trials (24-h free AUC, ∼550 mg · h/liter, versus 320 mg · h/liter in the phase 1 studies), 2 g of meropenem with 2 g of vaborbactam was also bactericidal against strains with meropenem-vaborbactam MICs of 16 mg/liter. In addition, this level of vaborbactam also suppressed the development of resistance observed using phase 1 exposures. In this pharmacodynamic model, exposures similar to 2 g of meropenem in combination with 2 g of vaborbactam administered every 8 h by a 3-h infusion in phase 3 trials produced antibacterial activity and suppressed the development of resistance against carbapenem-resistant KPC-producing strains of Enterobacteriaceae . Copyright © 2018 American Society for Microbiology.

Phenotypic method for differentiation of carbapenemases in Enterobacteriaceae: Study from north India

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Priya Datta

2012-01-01

Full Text Available Aims: Carbapenems are usually the choice of antimicrobials in infections caused by Enterobacteriaceae bacteria-producing ESBL (extended spectrum β-lactamases and Amp C. Resistance to carbapenems is mostly due to production of enzymes - Carbapenemases, which are divided into Ambler Classes A, B and D. Phenotypic detection and differentiation of types of Carbapenemases in carbapenem-resistant Enterobacteriaceae (CRE is important for proper infection control and appropriate patient management. Materials and Methods: The present study done in a tertiary care hospital from North India differentiates Class A (KPC type and B (MBL type carbapenemases among Enterobacteriaceae isolates by simple phenotypic method that uses both the inhibitors EDTA and phenylboronic acid. Results: Total of 330 strains of Enterobacteriaceae were included in the study. Out of these 330 strains, 26 strains were resistant to carbapenems. The prevalence of CRE in our Institute is 7.87% (26/330. Conclusions: The prevalence of Enterobacteriaceae strains producing MBL type carbapenemase in our health care setup is 5.75% (19/330. None of the strains among the carbapenem-resistant bacterial isolates showed production of KPC enzyme. The need of the hour is simple, rapid and cost effective tests which will be able to identify and distinguish resistant pathogens for improved patient outcome, facilitating efficient infection control and reducing the escalation of resistance.

First isolate of KPC-2-producing Klebsiella pneumonaie sequence type 23 from the Americas.

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Cejas, Daniela; Fernández Canigia, Liliana; Rincón Cruz, Giovanna; Elena, Alan X; Maldonado, Ivana; Gutkind, Gabriel O; Radice, Marcela A

2014-09-01

KPC-2-producing Klebsiella pneumoniae isolates mainly correspond to clonal complex 258 (CC258); however, we describe KPC-2-producing K. pneumoniae isolates belonging to invasive sequence type 23 (ST23). KPC-2 has scarcely been reported to occur in ST23, and this report describes the first isolation of this pathogen in the Americas. Acquisition of resistant markers in virulent clones could mark an evolutionary step toward the establishment of these clones as major nosocomial pathogens. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Acquisition of Carbapenem Resistance by Plasmid-Encoded-AmpC-Expressing Escherichia coli.

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van Boxtel, Ria; Wattel, Agnes A; Arenas, Jesús; Goessens, Wil H F; Tommassen, Jan

2017-01-01

Although AmpC β-lactamases can barely degrade carbapenems, if at all, they can sequester them and prevent them from reaching their targets. Thus, carbapenem resistance in Escherichia coli and other Enterobacteriaceae can result from AmpC production and simultaneous reduction of antibiotic influx into the periplasm by mutations in the porin genes. Here we investigated the route and genetic mechanisms of acquisition of carbapenem resistance in a clinical E. coli isolate carrying bla CMY-2 on a plasmid by selecting for mutants that are resistant to increasing concentrations of meropenem. In the first step, the expression of OmpC, the only porin produced in the strain under laboratory conditions, was lost, leading to reduced susceptibility to meropenem. In the second step, the expression of the CMY-2 β-lactamase was upregulated, leading to resistance to meropenem. The loss of OmpC was due to the insertion of an IS1 element into the ompC gene or to frameshift mutations and premature stop codons in this gene. The bla CMY-2 gene was found to be located on an IncIγ plasmid, and overproduction of the CMY-2 enzyme resulted from an increased plasmid copy number due to a nucleotide substitution in the inc gene. The clinical relevance of these genetic mechanisms became evident from the analysis of previously isolated carbapenem-resistant clinical isolates, which appeared to carry similar mutations. Copyright © 2016 American Society for Microbiology.

A cold active (2R,3R)-(-)-di-O-benzoyl-tartrate hydrolyzing esterase from Rhodotorula mucilaginosa.

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Zimmer, Christian; Platz, Tanja; Cadez, Neza; Giffhorn, Friedrich; Kohring, Gert-Wieland

2006-11-01

In a screening procedure a pink-colored yeast was isolated from enrichment cultures with (2R,3R)-(-)-di-O-benzoyl-tartrate (benzoyl-tartrate) as the sole carbon source. The organism saar1 was identified by morphological, physiological, and 18S ribosomal DNA/internal transcribed spacer analysis as Rhodotorula mucilaginosa, a basidiomycetous yeast. During growth the yeast hydrolyzed the dibenzoyl ester stoichiometrically to the monoester using the separated benzoate as the growth substrate, before the monoester was further cleaved into benzoate and tartrate, which were both metabolized. The corresponding benzoyl esterase was purified from the culture supernatant and characterized as a monomeric glycosylated 86-kDa protein with an optimum pH of 7.5 and an optimum temperature of 45 degrees C. At 0 degrees C the esterase still exhibited 20% of the corresponding activity at 30 degrees C, which correlates it to psychrophilic enzymes. The esterase could hydrolyze short chain p-nitrophenyl-alkyl esters and several benzoyl esters like benzoyl-methyl ester, ethylene-glycol-dibenzoyl ester, phenyl-benzoyl ester, cocaine, and 1,5-anhydro-D: -fructose-tribenzoyl ester. However feruloyl-ethyl ester was not hydrolyzed. The activity characteristics let the enzyme appear as a promising tool for synthesis of benzoylated compounds for pharmaceutical, cosmetic, or fine chemical applications, even at low temperatures.

The distribution of carbapenem- and colistin-resistance in Gram-negative bacteria from the Tamil Nadu region in India.

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Manohar, Prasanth; Shanthini, Thamaraiselvan; Ayyanar, Ramankannan; Bozdogan, Bulent; Wilson, Aruni; Tamhankar, Ashok J; Nachimuthu, Ramesh; Lopes, Bruno S

2017-07-01

The occurrence of carbapenem- and colistin-resistance among Gram-negative bacteria is increasing worldwide. The aim of this study was to understand the distribution of carbapenem- and colistin-resistance in two areas in Tamil Nadu, India. The clinical isolates (n=89) used in this study were collected from two diagnostic centres in Tamil Nadu, India. The bacterial isolates were screened for meropenem- and colistin-resistance. Further, resistance genes blaNDM-1, blaOXA-48-like, blaIMP, blaVIM, blaKPC, mcr-1 and mcr-2 and integrons were studied. The synergistic effect of meropenem in combination with colistin was assessed. A total of 89 bacterial isolates were studied which included Escherichia coli (n=43), Klebsiella pneumoniae (n=18), Pseudomonas aeruginosa (n=10), Enterobacter cloacae (n=6), Acinetobacter baumannii (n=5), Klebsiella oxytoca (n=4), Proteus mirabilis (n=2) and Salmonella paratyphi (n=1). MIC testing showed that 58/89 (65 %) and 29/89 (32 %) isolates were resistant to meropenem and colistin, respectively, whereas 27/89 (30 %) isolates were resistant to both antibiotics. Escherichia coli, K. pneumoniae, K. oxytoca, Pseudomonas aeruginosa, and Enterobacter cloacae isolates were blaNDM-1-positive (n=20). Some strains of Escherichia coli, K. pneumoniae and K. oxytoca were blaOXA-181-positive (n=4). Class 1, 2 and 3 integrons were found in 24, 20 and 3 isolates, respectively. Nine NDM-1-positive Escherichia coli strains could transfer carbapenem resistance via plasmids to susceptible Escherichia coli AB1157. Meropenem and colistin showed synergy in 10/20 (50 %) isolates by 24 h time-kill studies. Our results highlight the distribution of carbapenem- and colistin-resistance in Gram-negative bacteria isolated from the Tamil Nadu region in South India.

Global prevalence of carbapenem resistance in neutropenic patients and association with mortality and carbapenem use: systematic review and meta-analysis.

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Righi, Elda; Peri, Anna Maria; Harris, Patrick N A; Wailan, Alexander M; Liborio, Mariana; Lane, Steven W; Paterson, David L

2017-03-01

Carbapenem-resistant Gram-negative bacteria are recognized as a cause of difficult-to-treat infections associated with high mortality. To perform a systematic review of currently available data on distribution, characteristics and outcome associated with carbapenem-resistant bloodstream infections in adult neutropenic patients. Included studies were identified through Medline, Embase and Cochrane databases between January 1995 and April 2016. Random effect meta-analysis was used to quantify the association between carbapenem resistance and mortality and between carbapenem exposure and resistance. A total of 30 studies from 21 countries were included. Overall carbapenem resistance varied from 2% to 53% (median 9%) among studies. Infections due to carbapenem-resistant Pseudomonas spp . were reported in 18 (60%) studies showing high median resistance rates (44% of all carbapenem-resistant Gram-negatives and 19% of Pseudomonas isolates). Resistance of Enterobacteriaceae was less commonly reported and bloodstream infections due to carbapenem-resistant Klebsiella spp. were mainly documented from endemic areas (Greece, Italy, Israel). Carbapenem resistance in Acinetobacter spp. was reported in 9 (30%) studies (median resistance 58% of Acinetobacter isolates). Mortality rates ranged from 33% to 71% (median 50%) in patients with carbapenem-resistant infections. Carbapenem resistance appeared to correlate with mortality (OR 4.89, 95% CI 3.30-7.26) and previous exposure to carbapenems (OR 4.63, 95% CI 3.08-6.96). Carbapenem resistance represents a threat to neutropenic patients. In this group, resistance is likely promoted by previous carbapenem use and leads to high mortality rates. The knowledge of resistance patterns is crucial and can direct clinicians in the use of alternatives to carbapenem-based regimens. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please

Regulation of hydantoin-hydrolyzing enzyme expression in Agrobacterium tumefaciens strain RU-AE01.

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Jiwaji, Meesbah; Dorrington, Rosemary Ann

2009-10-01

Optically pure D-: amino acids, like D-: hydroxyphenylglycine, are used in the semi-synthetic production of pharmaceuticals. They are synthesized industrially via the biocatalytic hydrolysis of p-hydroxyphenylhydantoin using enzymes derived from Agrobacterium tumefaciens strains. The reaction proceeds via a three-step pathway: (a) the ring-opening cleavage of the hydantoin ring by a D-: hydantoinase (encoded by hyuH), (b) conversion of the resultant D-: N-carbamylamino acid to the corresponding amino acid by a D-: N-carbamoylase (encoded by hyuC), and (c) chemical or enzymatic racemization of the un-reacted hydantoin substrate. While the structure and biochemical properties of these enzymes are well understood, little is known about their origin, their function, and their regulation in the native host. We investigated the mechanisms involved in the regulation of expression of the hydantoinase and N-carbamoylase enzyme activity in A. tumefaciens strain RU-AE01. We present evidence for a complex regulatory network that responds to the growth status of the cells, the presence of inducer, and nitrogen catabolite repression. Deletion analysis and site-directed mutagenesis were used to identify regulatory elements involved in transcriptional regulation of hyuH and hyuC expression. Finally, a comparison between the hyu gene clusters in several Agrobacterium strains provides insight into the function of D-: selective hydantoin-hydrolyzing enzyme systems in Agrobacterium species.

Detection of the IncX3 plasmid carrying blaKPC-3 in a Serratia marcescens strain isolated from a kidney-liver transplanted patient.

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Gona, Floriana; Caio, Carla; Iannolo, Gioacchin; Monaco, Francesco; Di Mento, Giuseppina; Cuscino, Nicola; Fontana, Ignazio; Panarello, Giovanna; Maugeri, Gaetano; Mezzatesta, Maria Lina; Stefani, Stefania; Conaldi, Pier Giulio

2017-10-01

Dissemination of resistance to carbapenems among Enterobacteriaceae through plasmids is an increasingly important concern in health care worldwide. Here we report the first description of an IncX3 plasmid carrying the blaKPC-3 gene in a strain of Serratia marcescens isolated from a kidney-liver transplanted patient at the transplantation centre ISMETT (Istituto Mediterraneo per i Trapianti e Terapie ad Alta Specializzazione, Palermo, Italy). To localize the transposable element containing the resistance-associated gene Next-Generation Sequencing of the bacterial DNA was performed. S. marcescens was positive for blaKPC-3 and blaSHV-11 genes. The molecular analysis demonstrated that the blaKPC-3 gene of this bacterial strain was located in one copy of the Tn-3-like element Tn4401-a carried in a plasmid that is 53 392 bp in size and showed the typical IncX3 scaffold. Our data demonstrated the presence of a new blaKPC-3 harbouring the IncX3 plasmid in S. marcescens. The possible dissemination among Enterobacteriaceae of this type of plasmid should be monitored and evaluated in terms of clinical risk.

In vitro activities of carbapenems in combination with amikacin, colistin, or fosfomycin against carbapenem-resistant Acinetobacter baumannii clinical isolates.

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Singkham-In, Uthaibhorn; Chatsuwan, Tanittha

2018-01-31

Carbapenem-resistant Acinetobacter baumannii clinical isolates (n=23) were investigated for carbapenem resistance mechanisms and in vitro activities of carbapenems in combination with amikacin, colistin, or fosfomycin. Major carbapenem resistance mechanism was OXA-23 production. The vast majority of these isolates were OXA-23-producing A. baumannii ST195 and ST542, followed by novel STs, ST1417, and ST1423. The interuption of carO by a novel insertion sequence, ISAba40, was found in two isolates. The combinations of imipenem and fosfomycin, meropenem and amikacin, imipenem and amikacin, and imipenem and colistin were synergistic against carbapenem-resistant A. baumannii by 65.2%, 46.2%, 30.8%, and 17.4%, respectively. Surprisingly, the combination of imipenem and fosfomycin was the most effective in this study against A. baumannii, which is intrinsically resistant to fosfomycin. Imipenem and fosfomycin inhibit cell wall synthesis; therefore, fosfomycin may be an adjuvant and enhance the inhibition of cell wall synthesis of carbapenem-resistant A. baumannii when combined with imipenem. Copyright © 2018. Published by Elsevier Inc.

Emergence of serine carbapenemases (KPC and SME) among clinical strains of Enterobacteriaceae isolated in the United States Medical Centers: report from the MYSTIC Program (1999-2005).

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Deshpande, Lalitagauri M; Rhomberg, Paul R; Sader, Helio S; Jones, Ronald N

2006-12-01

Among 8885 Enterobacteriaceae tested in the 1999 to 2005 period as part of the USA Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program, 51 strains with increased imipenem and meropenem MIC values (> or =2 microg/mL) were detected. bla(KPC) was identified from 28 Klebsiella pneumoniae from 3 medical centers in the New York City area (8 ribotypes), 2 Klebsiella oxytoca from Arkansas (same ribotype), 7 Citrobacter freundii (6 from New York [5 ribotypes] and 1 from Delaware), 4 Enterobacter spp. from New York (2 species, different ribotypes), 3 Escherichia coli (2 from New York and 1 from Ohio, same ribotype), and 1 Serratia marcescens (New York). Sequencing confirmed KPC-2 or -3 in all of the strains. S. marcescens strains harboring SME-1 (2 isolates, same ribotype) and SME-2 (1 isolate) were identified from medical centers in Illinois and Washington state, respectively. Our results indicate that bla(KPC-2/3) has emerged widely (New York City area, Arkansas, Delaware, and Ohio) among Enterobacteriaceae isolated in the MYSTIC Program participant sites (2000-2005) and continues to be isolated from multiple species, as a result of clonal expansion and horizontal gene transfer. The escalating occurrence (0.35%) of serine carbapenemases could compromise the role of carbapenems and other beta-lactams in USA clinical practice although observed in only a few locations to date.

40 CFR 721.4585 - Lecithins, phospholipase A2-hydrolyzed.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Lecithins, phospholipase A2-hydrolyzed... Substances § 721.4585 Lecithins, phospholipase A2-hydrolyzed. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substances identified generically as lecithins...

Rapid Increase in Prevalence of Carbapenem-Resistant Enterobacteriaceae (CRE) and Emergence of Colistin Resistance Gene mcr-1 in CRE in a Hospital in Henan, China.

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Li, Yi; Sun, Qiao-Ling; Shen, Yingbo; Zhang, Yangjunna; Yang, Jun-Wen; Shu, Ling-Bin; Zhou, Hong-Wei; Wang, Yang; Wang, Bing; Zhang, Rong; Wang, Shaolin; Shen, Zhangqi

2018-04-01

The global spread of carbapenem-resistant Enterobacteriaceae (CRE) is one of the most severe threats to human health in a clinical setting. The recent emergence of plasmid-mediated colistin resistance gene mcr-1 among CRE strains greatly compromises the use of colistin as a last resort for the treatment of infections caused by CRE. This study aimed to understand the current epidemiological trends and characteristics of CRE from a large hospital in Henan, the most populous province in China. From 2014 to 2016, a total of 7,249 Enterobacteriaceae isolates were collected from clinical samples, among which 18.1% (1,311/7,249) were carbapenem resistant. Carbapenem-resistant Klebsiella pneumoniae and carbapenem-resistant Escherichia coli were the two most common CRE species, with Klebsiella pneumoniae carbapenemases (KPC) and New Delhi metallo-β-lactamases (NDM), respectively, responsible for the carbapenem resistance of the two species. Notably, >57.0% ( n = 589) of the K. pneumoniae isolates from the intensive care unit were carbapenem resistant. Furthermore, bla NDM-5 and mcr-1 were found to coexist in one E. coli isolate, which exhibited resistance to almost all tested antibiotics. Overall, we observed a significant increase in the prevalence of CRE isolates during the study period and suggest that carbapenems may no longer be considered to be an effective treatment for infections caused by K. pneumoniae in the studied hospital. Copyright © 2018 American Society for Microbiology.

Carbapenem-resistant-only Pseudomonas aeruginosa infection in patients formerly infected by carbapenem-susceptible strains.

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Tsai, Ming-Han; Wu, Tsu-Lan; Su, Lin-Hui; Lo, Wei-Lin; Chen, Chyi-Liang; Liang, Yi-Hua; Chiu, Cheng-Hsun

2014-12-01

Pseudomonas aeruginosa isolates that were initially carbapenem-susceptible and later became selective carbapenem-resistant following antimicrobial therapy were identified from individual cases during the same hospitalisation. Cross-resistance to other β-lactams was not found and their susceptibilities remained identical in consecutive isolates. Real-time quantitative reverse transcription PCR was performed to investigate the role of OprD, an outer membrane protein regulating the entry of carbapenems, in the appearance of carbapenem-resistant-only P. aeruginosa (CROPA). Fifteen paired isolates of carbapenem-susceptible P. aeruginosa (CS-PA) and CROPA were identified. All of the cases had carbapenem exposure history within 1 month before the appearance of CROPA (mean 10 days). Reduced OprD expression was found in 93% (14/15) of the isolates, suggesting that oprD inactivation was the major contributor to selective carbapenem resistance. Of the 14 cases with CROPA due to oprD mutation, 71% (10/14) were persistent infection, as genotype analysis revealed that their paired strains were isogenic; 29% (4/14) represented re-infections as they were heterogenic, suggesting that oprD-deficient CROPA existed in the hospital and that carbapenem selective pressure promoted its spread to patients. We conclude that CROPA may occur soon after the use of carbapenems to treat CS-PA infections and that oprD mutation is the major mechanism of resistance in CROPA. Restriction of empirical use of carbapenems by antibiotic stewardship is important to halt the occurrence of CROPA. Copyright © 2014 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Carbapenem stewardship: does ertapenem affect Pseudomonas susceptibility to other carbapenems? A review of the evidence.

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Nicolau, David P; Carmeli, Yehuda; Crank, Christopher W; Goff, Debra A; Graber, Christopher J; Lima, Ana Lucia L; Goldstein, Ellie J C

2012-01-01

The group 2 carbapenems (imipenem, meropenem and, more recently, doripenem) have been a mainstay of treatment for patients with serious hospital infections caused by Pseudomonas aeruginosa, Enterobacteriaceae and other difficult-to-treat Gram-negative pathogens as well as mixed aerobic/anaerobic infections. When ertapenem, a group 1 carbapenem, was introduced, questions were raised about the potential for ertapenem to select for imipenem- and meropenem-resistant Pseudomonas. Results from ten clinical studies evaluating the effect of ertapenem use on the susceptibility of Pseudomonas to carbapenems have uniformly shown that ertapenem use does not result in decreased Pseudomonas susceptibility to these antipseudomonal carbapenems. Here we review these studies evaluating the evidence of how ertapenem use affects P. aeruginosa as well as provide considerations for ertapenem use in the context of institutional stewardship initiatives. Copyright © 2011 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Molecular epidemiology and drug resistant mechanism in carbapenem-resistant Klebsiella pneumoniae isolated from pediatric patients in Shanghai, China.

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Zhang, Xingyu; Chen, Di; Xu, Guifeng; Huang, Weichun; Wang, Xing

2018-01-01

Infection by carbapenem-resistant Klebsiella pneumoniae (CR-KP) is a public health challenge worldwide, in particular among children, which was associated with high morbidity and mortality rates. There was limited data in pediatric populations, thus this study aimed to investigate molecular epidemiology and drug resistant mechanism of CR-KP strains from pediatric patients in Shanghai, China. A total of 41 clinical CR-KP isolates from sputum, urine, blood or drainage fluid were collected between July 2014 and May 2015 in Shanghai Children's Medical Center. Multilocus sequence typing (MLST), antibiotic susceptibility testing, PCR amplification and sequencing of the drug resistance associated genes were applied to all these isolates. MLST analysis revealed 16 distinct STs identified within the 41 isolates, among which the most frequently represented were ST11(19.5%),ST25(14.6%),ST76(14.6%),ST37(9.8%).One new ST was first identified. All CR-KP isolates showed MDR phenotypes and were resistance to ceftazidime, imipenem, piperacillin / tazobactam, ceftriaxone, ampicillin /sulbactam, aztreonam. They were confirmed as carbapenemase producer, NDM-1 (56.1%, 23/41), IMP (26.8%, 11/41), KPC-2 (22.0%, 9/41) were detected. Of note, two isolates carried simultaneously both NDM-1 and IMP-4. All CR-KP strains contained at least one of extended spectrum β-lactamase genes tested(TEM, SHV, OXA-1, CTX-M group) and six isolates carried both ESBL and AmpC genes(DHA-1). Among the penicllinase and β-lactamase genes, the most frequently one is SHV(92.7%,38/41), followed by TEM-1(68.3%,28/41), CTX-M-14(43.9%,18/41), CTX-M-15(43.9%,14/41), OXA-1(14.6%,6/41). In the present study, NDM-1-producing isolates was the predominant CR-KP strains in children, follow by IMP and KPC-producing strains. NDM-1and IMP-4 were more frequent than KPC-2 and showed a multiclonal background. Those suggested carbapenem-resistant in children is diverse, and certain resistance mechanisms differ from prevalent

Resistance to Carbapenems in Non-Typhoidal Salmonella enterica Serovars from Humans, Animals and Food

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Javier Fernández

2018-04-01

Full Text Available Non-typhoidal serovars of Salmonella enterica (NTS are a leading cause of food-borne disease in animals and humans worldwide. Like other zoonotic bacteria, NTS have the potential to act as reservoirs and vehicles for the transmission of antimicrobial drug resistance in different settings. Of particular concern is the resistance to critical “last resort” antimicrobials, such as carbapenems. In contrast to other Enterobacteriaceae (e.g., Klebsiella pneumoniae, Escherichia coli, and Enterobacter, which are major nosocomial pathogens affecting debilitated and immunocompromised patients, carbapenem resistance is still very rare in NTS. Nevertheless, it has already been detected in isolates recovered from humans, companion animals, livestock, wild animals, and food. Five carbapenemases with major clinical importance—namely KPC (Klebsiella pneumoniae carbapenemase (class A, IMP (imipenemase, NDM (New Delhi metallo-β-lactamase, VIM (Verona integron-encoded metallo-β-lactamase (class B, and OXA-48 (oxacillinase, class D—have been reported in NTS. Carbapenem resistance due to the production of extended spectrum- or AmpC β-lactamases combined with porin loss has also been detected in NTS. Horizontal gene transfer of carbapenemase-encoding genes (which are frequently located on self-transferable plasmids, together with co- and cross-selective adaptations, could have been involved in the development of carbapenem resistance by NTS. Once acquired by a zoonotic bacterium, resistance can be transmitted from humans to animals and from animals to humans through the food chain. Continuous surveillance of resistance to these “last resort” antibiotics is required to establish possible links between reservoirs and to limit the bidirectional transfer of the encoding genes between S. enterica and other commensal or pathogenic bacteria.

Resistance to Carbapenems in Non-Typhoidal Salmonella enterica Serovars from Humans, Animals and Food.

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Fernández, Javier; Guerra, Beatriz; Rodicio, M Rosario

2018-04-08

Non-typhoidal serovars of Salmonella enterica (NTS) are a leading cause of food-borne disease in animals and humans worldwide. Like other zoonotic bacteria, NTS have the potential to act as reservoirs and vehicles for the transmission of antimicrobial drug resistance in different settings. Of particular concern is the resistance to critical "last resort" antimicrobials, such as carbapenems. In contrast to other Enterobacteriaceae (e.g., Klebsiella pneumoniae , Escherichia coli , and Enterobacter , which are major nosocomial pathogens affecting debilitated and immunocompromised patients), carbapenem resistance is still very rare in NTS. Nevertheless, it has already been detected in isolates recovered from humans, companion animals, livestock, wild animals, and food. Five carbapenemases with major clinical importance-namely KPC ( Klebsiella pneumoniae carbapenemase) (class A), IMP (imipenemase), NDM (New Delhi metallo-β-lactamase), VIM (Verona integron-encoded metallo-β-lactamase) (class B), and OXA-48 (oxacillinase, class D)-have been reported in NTS. Carbapenem resistance due to the production of extended spectrum- or AmpC β-lactamases combined with porin loss has also been detected in NTS. Horizontal gene transfer of carbapenemase-encoding genes (which are frequently located on self-transferable plasmids), together with co- and cross-selective adaptations, could have been involved in the development of carbapenem resistance by NTS. Once acquired by a zoonotic bacterium, resistance can be transmitted from humans to animals and from animals to humans through the food chain. Continuous surveillance of resistance to these "last resort" antibiotics is required to establish possible links between reservoirs and to limit the bidirectional transfer of the encoding genes between S. enterica and other commensal or pathogenic bacteria.

The risk of seizures among the carbapenems: a meta-analysis.

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Cannon, Joan P; Lee, Todd A; Clark, Nina M; Setlak, Paul; Grim, Shellee A

2014-08-01

A consensus exists among clinicians that imipenem/cilastatin is the most epileptogenic carbapenem, despite inconsistencies in the literature. We conducted a meta-analysis of all randomized controlled trials comparing carbapenems with each other or with non-carbapenem antibiotics to assess the risk of seizures for imipenem, meropenem, ertapenem and doripenem. In the risk difference (RD) analysis, there were increased patients with seizure (2 per 1000 persons, 95% CI 0.001, 0.004) among recipients of carbapenems versus non-carbapenem antibiotics. This difference was largely attributed to imipenem as its use was associated with an additional 4 patients per 1000 with seizure (95% CI 0.002, 0.007) compared with non-carbapenem antibiotics, whereas none of the other carbapenems was associated with increased seizure. Similarly, in the pooled OR analysis, carbapenems were associated with a significant increase in the risk of seizures relative to non-carbapenem comparator antibiotics (OR 1.87, 95% CI 1.35, 2.59). The ORs for risk of seizures from imipenem, meropenem, ertapenem and doripenem compared with other antibiotics were 3.50 (95% CI 2.23, 5.49), 1.04 (95% CI 0.61, 1.77), 1.32 (95% CI 0.22, 7.74) and 0.44 (95% CI 0.13, 1.53), respectively. In studies directly comparing imipenem and meropenem, there was no difference in epileptogenicity in either RD or pooled OR analyses. The absolute risk of seizures with carbapenems was low, albeit higher than with non-carbapenem antibiotics. Although imipenem was more epileptogenic than non-carbapenem antibiotics, there was no statistically significant difference in the imipenem versus meropenem head-to-head comparison. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Effect of carbapenem consumption patterns on the molecular epidemiology and carbapenem resistance of Acinetobacter baumannii.

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Mózes, Julianna; Ebrahimi, Fatemeh; Gorácz, Orsolya; Miszti, Cecília; Kardos, Gábor

2014-12-01

This study investigated the molecular epidemiology of Acinetobacter baumannii in the University of Debrecen in relation to antibiotic consumption. Overall and ward-specific antibiotic consumption was measured by the number of defined daily doses (DDD) per 100 bed-days between 2002 and 2012. Consumption was analysed against the number of A. baumannii positive patients per 100 bed-days, number of isolates per positive sample, and proportion of carbapenem resistant A. baumannii, using time-series analysis. Altogether 160 A. baumannii isolates from different wards were collected and analysed. Carbapenemase genes bla(OXA-23-like), bla(OXA-24-like), bla(OXA-48-like), bla(OXA-51-like), bla(OXA-58-like) and integrons were sought by PCR. Relatedness of isolates was assessed by PFGE. Prevalence and carbapenem resistance of A. baumannii were statistically associated with carbapenem consumption. Prevalence data followed carbapenem usage with three quarterly lags (r = 0.51-0.53, Pcarbapenem consumption was associated with the carbapenem-susceptible cluster, as well as with the carbapenem-susceptible isolates in the cluster with variable susceptibility. Wards with high carbapenem usage almost exclusively harboured isolates from carbapenem-resistant clusters. All clusters were dominated by isolates of one or two wards, but most wards were represented in multiple clusters. Increases in prevalence and carbapenem resistance of A. baumannii were associated with usage of meropenem and ertapenem but not of imipenem, which led to the spread of multiple clones in the University. © 2014 The Authors.

Evolving beta-lactamase epidemiology in Enterobacteriaceae from Italian nationwide surveillance, October 2013: KPC-carbapenemase spreading among outpatients.

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Giani, Tommaso; Antonelli, Alberto; Caltagirone, Mariasofia; Mauri, Carola; Nicchi, Jessica; Arena, Fabio; Nucleo, Elisabetta; Bracco, Silvia; Pantosti, Annalisa; Luzzaro, Francesco; Pagani, Laura; Rossolini, Gian Maria

2017-08-03

Extended-spectrum beta-lactamases (ESBLs), AmpC-type beta-lactamases (ACBLs) and carbapenemases are among the most important resistance mechanisms in Enterobacteriaceae. This study investigated the presence of these resistance mechanisms in consecutive non-replicate isolates of Escherichia coli (n = 2,352), Klebsiella pneumoniae (n = 697), and Proteus mirabilis (n = 275) from an Italian nationwide cross-sectional survey carried out in October 2013. Overall, 15.3% of isolates were non-susceptible to extended-spectrum cephalosporins but susceptible to carbapenems (ESCR-carbaS), while 4.3% were also non-susceptible to carbapenems (ESCR-carbaR). ESCR-carbaS isolates were contributed by all three species, with higher proportions among isolates from inpatients (20.3%) but remarkable proportions also among those from outpatients (11.1%). Most ESCR-carbaS isolates were ESBL-positive (90.5%), and most of them were contributed by E. coli carrying bla CTX-M group 1 genes. Acquired ACBLs were less common and mostly detected in P. mirabilis. ESCR-carbaR isolates were mostly contributed by K. pneumoniae (25.1% and 7.7% among K. pneumoniae isolates from inpatients and outpatients, respectively), with bla KPC as the most common carbapenemase gene. Results showed an increasing trend for both ESBL and carbapenemase producers in comparison with previous Italian surveys, also among outpatients. This article is copyright of The Authors, 2017.

Association of ertapenem and antipseudomonal carbapenem usage and carbapenem resistance in Pseudomonas aeruginosa among 12 hospitals in Queensland, Australia.

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McDougall, David A J; Morton, Anthony P; Playford, E Geoffrey

2013-02-01

The objective of this study was to determine the association between ertapenem and antipseudomonal carbapenem use and carbapenem resistance in Pseudomonas aeruginosa in 12 hospitals in Queensland, Australia. Data on usage of ertapenem and other antipseudomonal carbapenems, measured in defined daily doses per 1000 occupied bed-days, were collated using statewide pharmacy dispensing and distribution software from January 2007 until June 2011. The prevalence of unique carbapenem-resistant P. aeruginosa isolates derived from statewide laboratory information systems was collected for the same time period. Mixed-effects models were used to determine any relationship between ertapenem and antipseudomonal carbapenem usage and carbapenem resistance among P. aeruginosa isolates in the 12 hospitals analysed. No relationship between ertapenem usage and P. aeruginosa carbapenem resistance was observed. The introduction of ertapenem did not replace antipseudomonal carbapenem prescribing to any significant extent. However, an association between greater usage of antipseudomonal carbapenems and greater P. aeruginosa carbapenem resistance was demonstrated. It is likely that the only mechanism by which ertapenem can improve P. aeruginosa resistance patterns is by being used as a substitute for, rather than in addition to, antipseudomonal carbapenems.

Enzymatic hydrolyzing performance of Acremonium cellulolyticus and Trichoderma reesei against three lignocellulosic materials

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Murakami Katsuji

2009-10-01

Full Text Available Abstract Background Bioethanol isolated from lignocellulosic biomass represents one of the most promising renewable and carbon neutral alternative liquid fuel sources. Enzymatic saccharification using cellulase has proven to be a useful method in the production of bioethanol. The filamentous fungi Acremonium cellulolyticus and Trichoderma reesei are known to be potential cellulase producers. In this study, we aimed to reveal the advantages and disadvantages of the cellulase enzymes derived from these fungi. Results We compared A. cellulolyticus and T. reesei cellulase activity against the three lignocellulosic materials: eucalyptus, Douglas fir and rice straw. Saccharification analysis using the supernatant from each culture demonstrated that the enzyme mixture derived from A. cellulolyticus exhibited 2-fold and 16-fold increases in Filter Paper enzyme and β-glucosidase specific activities, respectively, compared with that derived from T. reesei. In addition, culture supernatant from A. cellulolyticus produced glucose more rapidly from the lignocellulosic materials. Meanwhile, culture supernatant derived from T. reesei exhibited a 2-fold higher xylan-hydrolyzing activity and produced more xylose from eucalyptus (72% yield and rice straw (43% yield. Although the commercial enzymes Acremonium cellulase (derived from A. cellulolyticus, Meiji Seika Co. demonstrated a slightly lower cellulase specific activity than Accellerase 1000 (derived from T. reesei, Genencor, the glucose yield (over 65% from lignocellulosic materials by Acremonium cellulase was higher than that of Accellerase 1000 (less than 60%. In addition, the mannan-hydrolyzing activity of Acremonium cellulase was 16-fold higher than that of Accellerase 1000, and the conversion of mannan to mannobiose and mannose by Acremonium cellulase was more efficient. Conclusion We investigated the hydrolysis of lignocellulosic materials by cellulase derived from two types of filamentous fungi. We

The Impact of a Carbapenem-Resistant Enterobacteriaceae Outbreak on Facilitating Development of a National Infrastructure for Infection Control in Israel.

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Schwaber, Mitchell J; Carmeli, Yehuda

2017-11-29

In 2006 the Israeli healthcare system faced an unprecedented outbreak of carbapenem-resistant Enterobacteriaceae, primarily involving KPC-producing Klebsiella pneumoniae clonal complex CC258. This public health crisis exposed major gaps in infection control. In response, Israel established a national infection control infrastructure. The steps taken to build this infrastructure and benefits realized from its creation are described here. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

7-methylguanosine diphosphate (m(7)GDP) is not hydrolyzed but strongly bound by decapping scavenger (DcpS) enzymes and potently inhibits their activity.

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Wypijewska, Anna; Bojarska, Elzbieta; Lukaszewicz, Maciej; Stepinski, Janusz; Jemielity, Jacek; Davis, Richard E; Darzynkiewicz, Edward

2012-10-09

Decapping scavenger (DcpS) enzymes catalyze the cleavage of a residual cap structure following 3' → 5' mRNA decay. Some previous studies suggested that both m(7)GpppG and m(7)GDP were substrates for DcpS hydrolysis. Herein, we show that mononucleoside diphosphates, m(7)GDP (7-methylguanosine diphosphate) and m(3)(2,2,7)GDP (2,2,7-trimethylguanosine diphosphate), resulting from mRNA decapping by the Dcp1/2 complex in the 5' → 3' mRNA decay, are not degraded by recombinant DcpS proteins (human, nematode, and yeast). Furthermore, whereas mononucleoside diphosphates (m(7)GDP and m(3)(2,2,7)GDP) are not hydrolyzed by DcpS, mononucleoside triphosphates (m(7)GTP and m(3)(2,2,7)GTP) are, demonstrating the importance of a triphosphate chain for DcpS hydrolytic activity. m(7)GTP and m(3)(2,2,7)GTP are cleaved at a slower rate than their corresponding dinucleotides (m(7)GpppG and m(3)(2,2,7)GpppG, respectively), indicating an involvement of the second nucleoside for efficient DcpS-mediated digestion. Although DcpS enzymes cannot hydrolyze m(7)GDP, they have a high binding affinity for m(7)GDP and m(7)GDP potently inhibits DcpS hydrolysis of m(7)GpppG, suggesting that m(7)GDP may function as an efficient DcpS inhibitor. Our data have important implications for the regulatory role of m(7)GDP in mRNA metabolic pathways due to its possible interactions with different cap-binding proteins, such as DcpS or eIF4E.

Options for treating carbapenem-resistant Enterobacteriaceae.

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Rafailidis, Petros I; Falagas, Matthew E

2014-12-01

To address the therapeutic management of carbapenem-resistant Enterobacteriaceae on the basis of literature of the last 12 months. Retrospective and prospective (nonrandomized noncontrolled) studies provide data regarding the management of infections due to carbapenem-resistant Enterobacteriaceae. The combination of a carbapenem with colistin or high-dose tigecycline or aminoglycoside or even triple carbapenem-containing combinations if the minimum inhibitory concentration (MIC) range of carbapenem (meropenem and imipenem) resistance is 8 mg/l or less seems to have an advantage over monotherapy with either colistin or tigecycline or fosfomycin. For Enterobacteriaceae with MIC for carbapenems over 8 mg/l, combination regimens involve colistin, tigecycline usually administered in a double dose than that suggested by its manufacturer, fosfomycin and aminoglycosides in various combinations. Suggestions based on the limited literature cannot be made safely. Combination regimens involving carbapenems for Enterobacteriaceae with MICs 8 mg/l or less for carbapenems (in dual combination with colistin or high-dose tigecycline or aminoglycoside or even triple combinations) seem to confer some therapeutic advantage over monotherapy. For Enterobacteriaceae with higher than the above-mentioned MICs, a combination of two or even three antibiotics among colistin, high-dose tigecycline, aminoglycoside and fosfomycin seems to confer decreased mortality.

Recent updates of carbapenem antibiotics.

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El-Gamal, Mohammed I; Brahim, Imen; Hisham, Noorhan; Aladdin, Rand; Mohammed, Haneen; Bahaaeldin, Amany

2017-05-05

Carbapenems are among the most commonly used and the most efficient antibiotics since they are relatively resistant to hydrolysis by most β-lactamases, they target penicillin-binding proteins, and generally have broad-spectrum antibacterial effect. In this review, we described the initial discovery and development of carbapenems, chemical characteristics, in vitro/in vivo activities, resistance studies, and clinical investigations for traditional carbapenem antibiotics in the market; imipenem-cilastatin, meropenem, ertapenem, doripenem, biapenem, panipenem/betamipron in addition to newer carbapenems such as razupenem, tebipenem, tomopenem, and sanfetrinem. We focused on the literature published from 2010 to 2016. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

EFFECT OF TOBRACEF IN CARBAPENEM RESISTANT PNEUMONIA INFECTION

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A. Ahmad, V.K. Dwivedi * , and M. Chaudhary

2010-01-01

To determine ef ect of Tobracef and imipenem drug on antioxidant enzyme actvity and lipid peroxidation leveland some biochemical parametrs in carbapenem resistant pneumonia infection rat model. Total 40 rats wereselected and diveded into 4 groups of 10 rats each. Group I was control group; group II was infected via A.baumanni bacterial strain. Group III and IV were infected plus treated group with tobracef and imipenemdrugs.Our results showed that a significant (p

Wood hydrolyzate treatments for improved fermentation of wood sugars to 2,3-butanediol

Energy Technology Data Exchange (ETDEWEB)

Frazer, F.R.; McCaskey, T.A.

1989-01-01

Acid-hydrolyzed hardwood contains compounds inhibitory to micro-organisms that convert wood sugars to fermentation products such as fuels and chemicals. Several methods of treating acid-hydrolyzed hardwood (hydrolyzate) to reduce the levels of potential microbial inhibitors (acetate, furfural, sulfate, and phenolics) were evaluated. The methods evaluated were precipitation with calcium hydroxide, extraction with organic solvents, treatment with ion-exchange resins, adsorption resins, and activated charcoal. Treatment of the hydrolyzate with an anion exchange resin (Amberlite IRA-400) was the most effective method for removing potential inhibitors. Non-treatment hydrolyzate adjusted to pH 6 inhibited growth of a 2,3-butanediol-producing culture of Klebsiella pneumoniae. However, hydrolyzate treated with Amberlite IRA-400 was not inhibitory and resulted in yields of 2,3-butanediol that were greater than 90% of theoretical. (author).

High mortality of bloodstream infection outbreak caused by carbapenem-resistant P. aeruginosa producing SPM-1 in a bone marrow transplant unit.

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Chaves, Lucas; Tomich, Lísia Moura; Salomão, Matias; Leite, Gleice Cristina; Ramos, Jessica; Martins, Roberta Ruedas; Rizek, Camila; Neves, Patricia; Batista, Marjorie Vieira; Amigo, Ulysses; Guimaraes, Thais; Levin, Anna Sara; Costa, Silvia Figueiredo

2017-12-01

Carbapenem resistance in P. aeruginosa is increasing worldwide. In Brazil, SPM-1 is the main P. aeruginosa carbapenemase identified. Little is known about the virulence factor in SPM-1 clones.Methodolgy. We describe a carbapenem-resistant P. aeruginosa bloodstream infection (CRPa-BSI) outbreak in a bone marrow transplant Unit (BMT). Twenty-nine CRPa-BSI cases were compared to 58 controls. Microbiological characteristics of isolates, such as sensitivity, carbapenemase gene PCR for P. aeruginosa, and PFGE are described, as well as the whole-genome sequence (WGS) of three strains.Results/Key findings. The cultures from environmental and healthcare workers were negative. Some isolates harboured KPC and SPM. The WGS showed that the 03 strains belonged to ST277, presented the same mutations in outer membrane protein, efflux pump, and virulence genes such as those involved in adhesion, biofilm, quorum-sensing and the type III secretion system, but differ regarding the carbapenemase profile. A predominant clone-producing SPM harbouring Tn 4371 was identified and showed cross-transmission; no common source was found. Overall mortality rate among cases was 79 %. The first multivariate analysis model showed that neutropenia (P=0.018), GVHD prophylaxis (P=0.016) and prior use of carbapenems (P=0.0089) were associated with CRPa-BSI. However, when MASCC>21 points and platelets were added in the final multivariate analysis, only prior use of carbapenems remained as an independent risk factor for CRPa-BSI (P=0.043). The predominant clone belonging to ST277 showed high mortality. Carbapenem use was the only risk factor associated with CRPa-BSI. This finding is a wake-up call for the need to improve management in BMT units.

Informing Antibiotic Treatment Decisions: Evaluating Rapid Molecular Diagnostics To Identify Susceptibility and Resistance to Carbapenems against Acinetobacter spp. in PRIMERS III.

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Evans, Scott R; Hujer, Andrea M; Jiang, Hongyu; Hill, Carol B; Hujer, Kristine M; Mediavilla, Jose R; Manca, Claudia; Tran, Thuy Tien T; Domitrovic, T Nicholas; Higgins, Paul G; Seifert, Harald; Kreiswirth, Barry N; Patel, Robin; Jacobs, Michael R; Chen, Liang; Sampath, Rangarajan; Hall, Thomas; Marzan, Christine; Fowler, Vance G; Chambers, Henry F; Bonomo, Robert A

2017-01-01

The widespread dissemination of carbapenem-resistant Acinetobacter spp. has created significant therapeutic challenges. At present, rapid molecular diagnostics (RMDs) that can identify this phenotype are not commercially available. Two RMD platforms, PCR combined with electrospray ionization mass spectrometry (PCR/ESI-MS) and molecular beacons (MB), for detecting genes conferring resistance/susceptibility to carbapenems in Acinetobacter spp. were evaluated. An archived collection of 200 clinical Acinetobacter sp. isolates was tested. Predictive values for susceptibility and resistance were estimated as a function of susceptibility prevalence and were based on the absence or presence of beta-lactamase (bla) NDM, VIM, IMP, KPC, and OXA carbapenemase genes (e.g., bla OXA-23 , bla OXA-24/40 , and bla OXA-58 found in this study) against the reference standard of MIC determinations. According to the interpretation of MICs, 49% (n = 98) of the isolates were carbapenem resistant (as defined by either resistance or intermediate resistance to imipenem). The susceptibility sensitivities (95% confidence interval [CI]) for imipenem were 82% (74%, 89%) and 92% (85%, 97%) for PCR/ESI-MS and MB, respectively. Resistance sensitivities (95% CI) for imipenem were 95% (88%, 98%) and 88% (80%, 94%) for PCR/ESI-MS and MB, respectively. PRIMERS III establishes that RMDs can discriminate between carbapenem resistance and susceptibility in Acinetobacter spp. In the context of a known prevalence of resistance, SPVs and RPVs can inform clinicians regarding the best choice for empiric antimicrobial therapy against this multidrug-resistant pathogen. Copyright © 2016 American Society for Microbiology.

Resistencia a carbapenemes en aislamientos de Pseudomonas aeruginosa: un ejemplo de interacción entre distintos mecanismos Carbapenem resistance in Pseudomonas aeruginosa isolates: an example of interaction between different mechanisms

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Gisela Santella

2011-12-01

outer membrane protein absent in the resistant isolates and to determine both the causes of its absence in the membrane and the presence of other mechanisms of carbapenem resistance in clinical isolates of Pseudomonas aeruginosa. METHODS: Twenty isolates from an outbreak of P. aeruginosa previously characterized as metallo-beta-lactamase IMP-13 producers were studied. All the isolates exhibited equal expression of the IMP-13 enzyme, but only five of them were carbapenem-resistant. It was found that the five resistant isolates lacked a outer membrane protein. The oprD and ampC genes were sequenced; the outer membrane proteins were identified using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF mass spectrometry; the OprD and AmpC expressions, as well as the Mex efflux system, were assessed by real-time polymerase chain reaction; and finally, the contribution of reduced OprD to carbapenem resistance was determined. RESULTS: The absent outer membrane protein in group R was identified as OprD-TS; however, no variations in its expression were observed. The oprD gene presented mutations in the five resistant isolates. The production of AmpC PDC-5-type enzyme and the MexAB-OprM efflux system was the same in both carbapenem-sensitive and ‑resistant isolates. The contribution of the combined presence of IMP-13 and reduced OprD to increased resistance was examined. CONCLUSIONS: Different mechanisms contribute to carbapenem resistance in IMP-13-producing isolates. The possibility that these IMP-13-producing isolates could go undetected poses a latent risk when selecting mutants with added resistance mechanisms in order to enhance carbapenem resistance.

Outbreak of carbapenem-resistant Klebsiella pneumoniae: two-year epidemiologic follow-up in a tertiary hospital

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Graziella Hanna Pereira

2013-02-01

Full Text Available This study describes a carbapenem-resistant Klebsiella pneumoniae (CRKP outbreak that occurred from October 2008-December 2010. Polymerase chain reaction assays were performed to detect the blaKPC gene and molecular typing was performed using pulsed-field gel electrophoresis (PFGE. There were 33 CRKP infections; PFGE revealed five genotypes: genotype A in five (15%, B in 18 (55%, C in eight (24% and two unique profiles. Genotype B was disseminated in all hospital units and belonged to the same clone identified in 11 different hospitals in the state of São Paulo. Sixteen (48% patients died. Seven isolates (21% were resistant to polymyxin B and 45% were resistant to tigecycline and amikacin.

Detection of multidrug-resistant Pseudomonas aeruginosa harboring bla GES-1 and bla GES-11 in Recife, Brazil

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Valdemir Vicente da Silva Júnior

Full Text Available Abstract INTRODUCTION: Pseudomonas aeruginosa, an important pathogen globally, presents several resistance mechanisms. This study aimed to investigate the presence of bla GES in clinical isolates of Pseudomonas aeruginosa obtained from various clinical specimens from patients admitted to three different hospitals in Recife, Brazil. The Guiana extended spectrum beta-lactamase (GES enzymes are responsible for conferring broad spectrum resistance to beta-lactam drugs, including the carbapenems. METHODS: A total of 100 carbapenem-resistant P. aeruginosa isolates underwent polymerase chain reaction (PCR testing to identify bla GES, bla KPC, bla SPM-1, bla IMP, and bla VIM. Additionally, PCR products positive for bla GES were sequenced. The clonal profiles of these same isolates were then determined by means of enterobacterial repetitive intergenic consensus (ERIC-PCR analysis. RESULTS: PCR analysis revealed that four isolates harbored bla GES; DNA sequencing showed that two harbored bla GES-1 and two bla GES-11. Beta-lactamase genes bla SPM-1, bla IMP, bla VIM, and bla KPC were investigated; none of these genes was detected. Automated susceptibility testing methods (Vitek®2, bioMérieux showed that the bla GES-1-positive isolates were only susceptible to polymyxin B. The patterns obtained with ERIC-PCR methods showed clonal relationship between the two isolates that harbored bla GES-11, whereas different clonal profiles were found in the isolates harboring bla GES-1. CONCLUSIONS: We detected the presence of bacterial isolates positive for two different variants of the enzyme GES in three different hospitals from Recife, Brazil. These enzymes have a great capacity for dissemination among Gram-negative bacteria and confer broad-spectrum resistance to beta-lactam antibiotics and to the carbapenems.

Composition of the enzymatic and acid hydrolyzates of gamma-irradiated rice straw

International Nuclear Information System (INIS)

Abad, L.V.; Banzon, R.B.; Rosa, A. de la

1989-01-01

Gamma irradiation was utilized to induce structural changes in rice straw that would enhance the conversion of its cellulose and ligno-cellulosic components to glucose and other reducing sugars. With the appropriate fermentation conditions these sugars can eventually be converted into alcohol. Rice straw materials were irradiated at varying doses (0-500 kgy) and hydrolyzed by the use of a) cellulose enzyme and b) 1% sulfuric acid. The composition of the hydrolyzates of rice straw was studied by thin layer chromatography (TLC) coupled with the Nelson-Somogyi test for its quantification. Acid hydrolyzates of rice straw showed a maximum increase of 16.46% in its total reducing sugars at 300 Kgy. TLC of the acid hydrolyzates of rice straw revealed the presence of glucose, xylose, arabinose, and cellobiose. However, it was only with xylose that a significant increase in yield was observed with the non-irradiated straw 12.55% xylose yield was noted while with rice straw-irradiated at 400 Kgy a maximum yield of 15.90% xylose was obtained. Total reducing sugar of the enzymatic hydrolyzate of rice straw showed a maximum increase of 205% at 500 Kgy. TLC revealed that only glucose was present in the enzymatic hydrolyzate. Glucose yield increase from 2.49% (0 Kgy) to 7.31% (500 Kgy). The results showed that radiation pre-treatment of rice straw induces significant increases in reducing sugar for both enzymatic and hydrolyzate. (Auth.). 2 tabs.; 1 fig

Characterization of resistance mechanisms and genetic relatedness of carbapenem-resistant Acinetobacter baumannii isolated from blood, Italy.

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Migliavacca, Roberta; Espinal, Paula; Principe, Luigi; Drago, Monica; Fugazza, Giulia; Roca, Ignasi; Nucleo, Elisabetta; Bracco, Silvia; Vila, Jordi; Pagani, Laura; Luzzaro, Francesco

2013-02-01

The aim of this study was to characterize the resistance mechanisms and genetic relatedness of 21 carbapenem-resistant Acinetobacter baumannii blood isolates collected in Italy during a 1-year multicenter prospective surveillance study. Genes coding for carbapenemase production were identified by polymerase chain reaction (PCR) and sequencing. Pulsed-field gel electrophoresis (PFGE), multiplex PCRs for group identification, and multilocus sequence typing (MLST) were used to determine genetic relationships. Carbapenem resistance was consistently related to the production of oxacillinases, mostly the plasmid-mediated OXA-58 enzyme. Strains producing the OXA-23 enzyme (chromosomally mediated) were also detected. Seven PFGE clones were identified, some of which being related to international (ICL- I and ICL-II) or national clonal lineages. Multiplex PCRs identified 4 different groups (group 2 being dominant), further distinguishable in 6 sequence types by MLST. The heterogeneity of profiles highlights the diffusion of international and national clonal lineages in Italy. Continuous surveillance is needed for monitoring the spread of these worrisome strains equipped with multiple drug resistance mechanisms. Copyright © 2013 Elsevier Inc. All rights reserved.

[Investigation of OXA type beta-lactamases and PFGE patterns in Acinetobacter baumannii strains resistant to carbapenems].

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Keyik, Serafettin; Arslan, Uğur; Türk Dağı, Hatice; Seyhan, Tuba; Fındık, Duygu

2014-10-01

Acinetobacter baumannii is an important opportunistic and multidrug-resistant pathogen leading to nosocomial infections. Over the last 10 years, a significant and threatening increase in resistance to carbapenems, mainly due to the dissemination of class D beta-lactamases, has been reported in A.baumannii worldwide. The most common types of beta-lactamases causing carbapenem resistance in A.baumannii are the OXA-23, OXA-24, OXA-40, OXA-58 and OXA-143 type serine beta-lactamases. The aim of this study was to investigate the presence of OXA type beta-lactamases in carbapenem-resistant A.baumannii strains and the clonal relationship between the strains. A total of 105 non-duplicate carbapenem-resistant A.baumannii strains isolated from various clinical samples (68 blood, 18 bronchoalveolar lavage, 13 drainage, 3 urine, 2 cerebrospinal fluid and 1 catheter samples) in the Microbiology Laboratories of Selcuk University, Meram (2009-2012) and Selcuklu (2007-2008) Medical School Hospitals, were included in the study. The isolates were identified by conventional methods and Phoenix 100 BD (BD Diagnostic, USA) and Vitek II (bioMerieux, France) automated systems. Carbapenem susceptibility test was performed by Kirby-Bauer disk diffusion method according to the CLSI standards. bla(OXA 23-like), bla(OXA 24-like), bla(OXA 58-like) and bla(OXA 51-like) genes were amplified by multiplex PCR assay and clonal relatedness was investigated by pulsed-field gel electrophoresis (PFGE) using ApaI enzyme. The bla(OXA 51-like) gene was determined in all carbapenem-resistant A.baumannii isolates, while the bla(OXA 23-like) and bla(OXA 58-like) genes were detected in 46.6% and 53.3% of isolates, respectively. However bla(OXA 24-like) gene was not demonstrated in any isolates. bla(OXA 23-like) gene was determined in both Meram and Selcuklu Medical School hospitals, but bla(OXA 58-like) gene was detected only in Meram Medical School hospital. PFGE analysis of the isolates revealed 32 different

Functional blaKPC-2 sequences are present in United States beef cattle feces regardless of antibiotic use

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Recently, using quantitative PCR (qPCR) we detected blaKPC-2 in metagenomic DNA (mgDNA) prepared from the feces of 36 lots beef cattle "raised without antibiotics" (RWA) and 36 lots raised "conventionally" (CONV). Since a small internal fragment of the blaKPC-2 gene was targeted we sought to confirm...

Characterization of carbapenem-nonsusceptible Klebsiella pneumoniae bloodstream isolates at a Taiwanese hospital: clinical impacts of lowered breakpoints for carbapenems.

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Lee, N Y; Wu, J J; Lin, S H; Ko, W C; Tsai, L H; Yan, J J

2012-08-01

This study was conducted in order to characterize carbapenem-nonsusceptible Klebsiella pneumoniae isolates and to evaluate the impacts of recently lowered interpretative breakpoints for carbapenems for Enterobacteriaceae. Among 152 K. pneumoniae bloodstream isolates suspected as AmpC or extended-spectrum β-lactamase (ESBL) producers, 58 (38.2%) isolates were currently interpreted as nonsusceptible to ertapenem, imipenem, or meropenem, and 42 (72.4%) of them were categorized as carbapenem-susceptible by the previous criteria. The high revision rate was associated with the predominance (79.3%) of DHA-1 among the carbapenem-nonsusceptible isolates due to both polyclonal and clonal spread. ESBLs were common (~57%) in both ertapenem-susceptible and -nonsusceptible isolates; however, 84.8% of the carbapenem-nonsusceptible isolates were also AmpC producers. The IMP-8 metallo-β-lactamase was detected in three isolates. Polyacrylamide gel electrophoresis suggested decreased OmpK35 expression in all but one ertapenem-nonsusceptible isolate, and genetic disruptions of ompK35 and ompK36 were detected in 30 and six ertapenem-nonsusceptible isolates, respectively. A comparison between patients infected by AmpC- or ESBL-producing ertapenem-susceptible (n=62) isolates and those with isolates revised as ertapenem-nonsusceptible (n=41) revealed more cases of malignancies (36.6% versus 14.5%; p=0.01) and higher Charlson score (p=0.033) among the patients with ertapenem-nonsusceptible isolates; however, the acquisition of an isolate revised as carbapenem-nonsusceptible was not identified as an independent mortality risk factor.

Clinical and Molecular Epidemiology of Carbapenem-Resistant Enterobacteriaceae Among Adult Inpatients in Singapore.

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Marimuthu, Kalisvar; Venkatachalam, Indumathi; Khong, Wei Xin; Koh, Tse Hsien; Cherng, Benjamin Pei Zhi; Van La, My; De, Partha Pratim; Krishnan, Prabha Unny; Tan, Thean Yen; Choon, Raymond Fong Kok; Pada, Surinder Kaur; Lam, Choong Weng; Ooi, Say Tat; Deepak, Rama Narayana; Smitasin, Nares; Tan, Eng Lee; Lee, Jia Jun; Kurup, Asok; Young, Barnaby; Sim, Nancy Tee Wen; Thoon, Koh Cheng; Fisher, Dale; Ling, Moi Lin; Peng, Brenda Ang Sze; Teo, Yik-Ying; Hsu, Li Yang; Lin, Raymond Tzer Pin; Ong, Rick Twee-Hee; Teo, Jeanette; Ng, Oon Tek

2017-05-15

Since 2010, the incidence of carbapenem-resistant Enterobacteriaceae (CRE) has been increasing in Singapore. We analyzed the clinical and molecular epidemiology of CRE among adult inpatients in Singapore. Quarterly incidence of unique subjects (per 100000 patient-days) with positive clinical and surveillance cultures for CRE were estimated based on mandatory data submitted to the National Public Health Laboratory by public hospitals between 2010 and 2015. CRE-positive adult inpatients were prospectively recruited from 6 public sector hospitals between December 2013 and April 2015. Subjects answered a standardized epidemiologic questionnaire and provided samples for this study. Further clinical information was extracted from subjects' electronic medical records. Whole-genome sequencing was performed on study isolates to determine transmission clusters. Incidence of CRE clinical cultures among adult inpatients plateaued from 2013 (range: 7.73 to 10.32 per 100000 patient-days) following an initial increase between 2010 and end-2012. We prospectively recruited 249 subjects. Their median age was 65 years, 108 (43%) were female, and 161 (64.7%) had carbapenemase-producing Enterobacteriaceae (CPE). On multivariate analysis, prior carbapenem exposure (OR: 3.23; 95% CI: 1.67-6.25) and hematological malignancies (OR: 2.85; 95% CI: 1.10-7.41) were associated with non-carbapenemase-producing CRE (NCPE) (n = 88) compared with CPE (n = 161) subjects. Among 430 CRE isolates from the 249 subjects, 307(71.3%) were CPE, of which 154(50.2%) were blaKPC-positive, 97(31.6%) blaNDM-positive, and 42 (13.7%) blaOXA-positive. Klebsiella pneumoniae (n = 180, 41.9%), Escherichia coli (n = 129, 30.0%) and Enterobacter cloacae (n = 62, 14.4%) were the main Enterobacteriaceae species. WGS (n = 206) revealed diverse bacterial strain type (STs). The predominant blaKPC-positive plasmid was pHS102707 (n = 62, 55.4%) and the predominant blaNDM-positive plasmid was pNDM-ECS01 (n = 46, 48.9%). Five

Production of bioethanol from corn meal hydrolyzates

Energy Technology Data Exchange (ETDEWEB)

Ljiljana Mojovic; Svetlana Nikolic; Marica Rakin; Maja Vukasinovic [University of Belgrade, Belgrade (Serbia and Montenegro). Faculty of Technology and Metallurgy, Department of Biochemical Engineering and Biotechnology

2006-09-15

The two-step enzymatic hydrolysis of corn meal by commercially available {alpha}-amylase and glucoamylase and further ethanol fermentation of the obtained hydrolyzates by Saccharomyces cerevisiae yeast was studied. The conditions of starch hydrolysis such as substrate and enzyme concentration and the time required for enzymatic action were optimized taking into account both the effects of hydrolysis and ethanol fermentation. The corn meal hydrolyzates obtained were good substrates for ethanol fermentation by S. cerevisiae. The yield of ethanol of more than 80% (w/w) of the theoretical was achieved with a satisfactory volumetric productivity P (g/l h). No shortage of fermentable sugars was observed during simultaneous hydrolysis and fermentation. In this process, the savings in energy by carrying out the saccharification step at lower temperature (32{sup o}C) could be realized, as well as a reduction of the process time for 4 h. 31 refs., 5 figs., 2 tabs.

Carbapenems: Past, Present, and Future ▿

Science.gov (United States)

Papp-Wallace, Krisztina M.; Endimiani, Andrea; Taracila, Magdalena A.; Bonomo, Robert A.

2011-01-01

In this review, we summarize the current “state of the art” of carbapenem antibiotics and their role in our antimicrobial armamentarium. Among the β-lactams currently available, carbapenems are unique because they are relatively resistant to hydrolysis by most β-lactamases, in some cases act as “slow substrates” or inhibitors of β-lactamases, and still target penicillin binding proteins. This “value-added feature” of inhibiting β-lactamases serves as a major rationale for expansion of this class of β-lactams. We describe the initial discovery and development of the carbapenem family of β-lactams. Of the early carbapenems evaluated, thienamycin demonstrated the greatest antimicrobial activity and became the parent compound for all subsequent carbapenems. To date, more than 80 compounds with mostly improved antimicrobial properties, compared to those of thienamycin, are described in the literature. We also highlight important features of the carbapenems that are presently in clinical use: imipenem-cilastatin, meropenem, ertapenem, doripenem, panipenem-betamipron, and biapenem. In closing, we emphasize some major challenges and urge the medicinal chemist to continue development of these versatile and potent compounds, as they have served us well for more than 3 decades. PMID:21859938

75 FR 16132 - Agency Information Collection Activities: Proposed Collection; Comment Request

Science.gov (United States)

2010-03-31

... bacteria is that they are resistant to carbapenem (a class of beta- lactam antibiotics with a broad... Enterobacteriaceae (KPC) Producing Organisms through the Application of Recently Developed CDC/HICPAC Recommendations... Reductions of Infection Caused by Carbapenem Resistant Enterobacteriaceae (KPC) Producing Organisms Through...

Mapping the resistance-associated mobilome of a carbapenem-resistant Klebsiella pneumoniae strain reveals insights into factors shaping these regions and facilitates generation of a 'resistance-disarmed' model organism.

Science.gov (United States)

Bi, Dexi; Jiang, Xiaofei; Sheng, Zi-Ke; Ngmenterebo, David; Tai, Cui; Wang, Minggui; Deng, Zixin; Rajakumar, Kumar; Ou, Hong-Yu

2015-10-01

This study aims to investigate the landscape of the mobile genome, with a focus on antibiotic resistance-associated factors in carbapenem-resistant Klebsiella pneumoniae. The mobile genome of the completely sequenced K. pneumoniae HS11286 strain (an ST11, carbapenem-resistant, near-pan-resistant, clinical isolate) was annotated in fine detail. The identified mobile genetic elements were mapped to the genetic contexts of resistance genes. The blaKPC-2 gene and a 26 kb region containing 12 clustered antibiotic resistance genes and one biocide resistance gene were deleted, and the MICs were determined again to ensure that antibiotic resistance had been lost. HS11286 contains six plasmids, 49 ISs, nine transposons, two separate In2-related integron remnants, two integrative and conjugative elements (ICEs) and seven prophages. Sixteen plasmid-borne resistance genes were identified, 14 of which were found to be directly associated with Tn1721-, Tn3-, Tn5393-, In2-, ISCR2- and ISCR3-derived elements. IS26 appears to have actively moulded several of these genetic regions. The deletion of blaKPC-2, followed by the deletion of a 26 kb region containing 12 clustered antibiotic resistance genes, progressively decreased the spectrum and level of resistance exhibited by the resultant mutant strains. This study has reiterated the role of plasmids as bearers of the vast majority of resistance genes in this species and has provided valuable insights into the vital role played by ISs, transposons and integrons in shaping the resistance-coding regions in this important strain. The 'resistance-disarmed' K. pneumoniae ST11 strain generated in this study will offer a more benign and readily genetically modifiable model organism for future extensive functional studies. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Phenolic constituents and modulatory effects of Raffia palm leaf (Raphia hookeri extract on carbohydrate hydrolyzing enzymes linked to type-2 diabetes

Directory of Open Access Journals (Sweden)

Felix A. Dada

2017-10-01

Full Text Available This study sought to investigate the effects of Raffia palm (Raphia hookeri leaf extract on enzymes linked to type-2 diabetes mellitus (T2DM and pro-oxidant induced oxidative stress in rat pancreas. The extract was prepared and its α-amylase and α-glucosidase inhibitory effects were determined. Radical [2,2-diphenyl-1-picrylhydrazyl (DPPH] scavenging and Fe2+-chelating abilities, and inhibition of Fe2+-induced lipid peroxidation in rat pancreas homogenate were assessed. Furthermore, total phenol and flavonoid contents, reducing property, and high performance liquid chromatography diode array detector (HPLC-DAD fingerprint of the extract were also determined. Our results revealed that the extract inhibited α-amylase (IC50 = 110.4 μg/mL and α-glucosidase (IC50 = 99.96 μg/mL activities in concentration dependent manners which were lower to the effect of acarbose (amylase: IC50 = 18.30 μg/mL; glucosidase: IC50 = 20.31 μg/mL. The extract also scavenged DPPH radical, chelated Fe2+ and inhibited Fe2+-induced lipid peroxidation in rat pancreas all in concentration dependent manners with IC50 values of 402.9 μg/mL, 108.9 μg/mL and 367.0 μg/mL respectively. The total phenol and flavonoid contents were 39.73 mg GAE/g and 21.88 mg QAE/g respectively, while the reducing property was 25.62 mg AAE/g. The HPLC analysis revealed the presence of chlorogenic acid (4.17 mg/g and rutin (5.11 mg/g as the major phenolic compounds in the extract. Therefore, the ability of the extract to inhibit carbohydrate hydrolyzing enzymes and protect against pancreatic oxidative damage may be an important mechanisms supporting its antidiabetic properties and could make Raffia palm leaf useful in complementary/alternative therapy for management of T2DM. However, further studies such as in vivo should be carried out.

Bulgecin A as a β-lactam enhancer for carbapenem-resistant Pseudomonas aeruginosa and carbapenem-resistant Acinetobacter baumannii clinical isolates containing various resistance mechanisms.

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Skalweit, Marion J; Li, Mei

2016-01-01

Genetic screening of Pseudomonas aeruginosa (PSDA) and Acinetobacter baumannii (ACB) reveals genes that confer increased susceptibility to β-lactams when disrupted, suggesting novel drug targets. One such target is lytic transglycosylase. Bulgecin A (BlgA) is a natural product of Pseudomonas mesoacidophila and a lytic transglycosolase inhibitor that works synergistically with β-lactams targeting PBP3 for Enterobacteriaceae. BlgA also weakly inhibits di-Zn 2+ metallo-β-lactamases like L1 of Stenotrophomonas maltophilia . We hypothesized that because of its unique mechanism of action, BlgA could restore susceptibility to carbapenems in carbapenem-resistant PSDA (CR-PSDA) and carbapenem-resistant ACB, as well as ACB resistant to sulbactam. A BlgA-containing extract was prepared using a previously published protocol. CR-PSDA clinical isolates demonstrating a variety of carbapenem resistance mechanisms (VIM-2 carbapenemases, efflux mechanisms, and AmpC producer expression) were characterized with agar dilution minimum inhibitory concentration (MIC) testing and polymerase chain reaction. Growth curves using these strains were prepared using meropenem, BlgA extract, and meropenem plus BlgA extract. A concentrated Blg A extract combined with low concentrations of meropenem, was able to inhibit the growth of clinical strains of CR-PSDA for strains that had meropenem MICs ≥8 mg/L by agar dilution, and a clinical strain of an OXA-24 producing ACB that had a meropenem MIC >32 mg/L and intermediate ampicillin/sulbactam susceptibility. Similar experiments were conducted on a TEM-1 producing ACB strain resistant to sulbactam. BlgA with ampicillin/sulbactam inhibited the growth of this organism. As in Enterobacteriaceae, BlgA appears to restore the efficacy of meropenem in suppressing the growth of CR-PSDA and carbapenem-resistant ACB strains with a variety of common carbapenem resistance mechanisms. BlgA extract also inhibits VIM-2 β-lactamase in vitro. BlgA may prove to be

Sparing carbapenem usage.

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Wilson, A Peter R

2017-09-01

Carbapenem resistance in Gram-negative bacteria is increasing in many countries and use of carbapenems and antibiotics to which resistance is linked should be reduced to slow its emergence. There are no directly equivalent antibiotics and the alternatives are less well supported by clinical trials. The few new agents are expensive. To provide guidance on strategies to reduce carbapenem usage. A literature review was performed as described in the BSAC/HIS/BIA/IPS Joint Working Party on Multiresistant Gram-negative Infection Report. Older agents remain active against some of the pathogens, although expectations of broad-spectrum cover for empirical treatment have risen. Education, expert advice on treatment and antimicrobial stewardship can produce significant reductions in use. More agents may need to be introduced onto the antibiotic formulary of the hospital, despite the poor quality of scientific studies in some cases. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

ISAba1 Regulated OXA-23 Carbapenem Resistance in Acinetobacter baumannii Strains in Durban, South Africa.

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Agoba, Esther Eyram; Govinden, Usha; Peer, Abdool Kader Cassim; Osei Sekyere, John; Essack, Sabiha Yusuf

2018-03-20

This study investigated the molecular mechanisms of resistance to carbapenems and cephalosporins in 24 consecutive, multidrug-resistant Acinetobacter baumannii (MDRAB) isolates collected between January and April 2015 by a private sector laboratory in Durban, South Africa. All isolates were resistant to all carbapenems tested. bla OXA-23 and bla OXA-51 genes were found in 23 isolates, while bla OXA-24 , bla OXA-48 , and bla OXA-58 were absent in all isolates. The most prevalent extended-spectrum β-lactamase was TEM-116 (92%). bla ADC was present in 83.3% of isolates, of which two were new variants with three and five amino acid differences compared to Acinetobacter-derived cephalosporinase (ADC)-1, the first at positions 64E → K, 341N → T, and 342R → G and the second at positions 24G → D, 167S → P, 283R → F, 341N → T, and 342R → G, respectively. All isolates were negative for bla PER , bla CMY , bla GES , bla KPC , bla CTX-M , and bla SHV . Metallo-β-lactamase IMP and VIM were absent in all isolates, and NDM-1 was present in 1 isolate. ISAba1 was located upstream bla OXA-23 in all isolates and upstream bla ADC (30, 78, 79, 87 and the ADC variants) in 54.2% of the ADC-carrying isolates. None of the isolates had ISAba1 inserted upstream bla OXA-51 gene. Four isolates were clonally related and showed two clusters (A and B), while 20 isolates remained unclustered. There was no direct relationship between the clusters and the hospitals they were isolated from. This study reports the first NDM-1-producing carbapenem resistant Acinetobacter baumannii isolate in South Africa and highlights the presence of OXA-23, the known ADCs (ADC-30, ADC-78, ADC-79, and ADC-87), and two new ADC variants associated with ISAba1 from the private health sector in Durban, South Africa. The complexity and diversity of MDRAB severely limit treatment options.

Chromobacterium spp. harbour Ambler class A beta-lactamases showing high identity with KPC

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Gudeta, Dereje Dadi; Bortolaia, Valeria; Jayol, Aurelie

2016-01-01

Objectives: The origin of KPC is unknown. The aim of this study was to detect progenitors of KPC in silico and to functionally verify their beta-lactam hydrolysis activity. Methods: The sequence of KPC-2 was used to mine the NCBI protein sequence database. The best non-KPC hits were analysed by a......-lactamases with up to 76% aa identity to KPC from distinct Chromobacterium species is highly indicative of the role played by this genus in the evolution of KPC....

Carbapenem-resistant Klebsiella pneumoniae colonization in pediatric and neonatal intensive care units: risk factors for progression to infection.

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Akturk, Hacer; Sutcu, Murat; Somer, Ayper; Aydın, Derya; Cihan, Rukiye; Ozdemir, Aslı; Coban, Asuman; Ince, Zeynep; Citak, Agop; Salman, Nuran

2016-01-01

Little is known about factors associated with carbapenem-resistant Klebsiella pneumoniae infections in pediatric patients, who are initally colonized with carbapenem-resistant Klebsiella pneumoniae. A retrospective case-control study was conducted involving pediatric and neonatal intensive care units throughout a five-year period (January 2010-December 2014). Clinical and microbiological data were extracted from Hospital Infection Control Committee reports and patients' medical records. Risk factors were assessed in carbapenem-resistant Klebsiella pneumoniae colonized patients who developed subsequent systemic infection (cases) and compared to carbapenem-resistant Klebsiella pneumoniae colonized patients who did not develop infection (controls). Throughout the study period, 2.6% of patients admitted to neonatal intensive care units and 3.6% of patients admitted to pediatric intensive care units had become colonized with carbapenem-resistant Klebsiella pneumoniae. After a mean of 10.6±1.9 days (median: 7 days, range: 2-38 days) following detection of colonization, 39.0% of the carbapenem-resistant Klebsiella pneumoniae colonized patients in pediatric intensive care units and 18.1% of carbapenem-resistant Klebsiella pneumoniae colonized patients in neonatal intensive care units developed systemic carbapenem-resistant Klebsiella pneumoniae infection. Types of systemic carbapenem-resistant Klebsiella pneumoniae infections included bacteremia (n=15, 62.5%), ventilator-associated pneumonia (n=4, 16.6%), ventriculitis (n=2, 8.3%), intraabdominal infections (n=2, 8.3%), and urinary tract infection (n=1, 4.1%). A logistic regression model including parameters found significant in univariate analysis of carbapenem resistant Klebsiella pneumoniae colonization and carbapenem resistant Klebsiella pneumoniae infection groups revealed underlying metabolic disease (OR: 10.1; 95% CI: 2.7-37.2), previous carbapenem use (OR: 10.1; 95% CI: 2.2-40.1), neutropenia (OR: 13.8; 95% CI: 3

Cefmetazole for bacteremia caused by ESBL-producing enterobacteriaceae comparing with carbapenems.

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Fukuchi, Takahiko; Iwata, Kentaro; Kobayashi, Saori; Nakamura, Tatsuya; Ohji, Goh

2016-08-18

ESBL (Extended spectrum beta-lactamase) producing enterobacteriaceae are challenging organisms with little treatment options. Carbapenems are frequently used, but the emergence of carbapenem resistant enterobacteriaceae is a concerning issue, which may hinder the use of carbapenems. Although cephamycins such as cefoxitin, cefmetazole or cefotetan are effective against ESBL-producers in vitro, there are few clinical data demonstrating effects against bacteremia caused by these organisms. We performed a retrospective observational study on cases of bacteremia caused by ESBL-producers to investigate the efficacy of cefmetazole compared with carbapenems. We also evaluated whether the trend of antibiotic choice changed over years. Sixty-nine patients (male 34, age 69.2 ± 14.4), including two relapse cases, were reviewed for this analysis. The most common causative organisms were Escherichia coli (64, 93 %), followed by Klebsiella pneumoniae and K. oxytoca (2 each, 4 %). The group that received carbapenem therapy (43, 62 %) had increased severity in the Pittsburgh Bacteremic score than the group that received cefmetazole therapy, (1.5 ± 1.5 vs 2.5 ± 2.1, p = 0.048), while analysis of other factors didn't reveal any statistical differences. Five patients in the carbapenem group and one patient in the cefmetazole group died during the observation period (p = 0.24). CTX-M-9 were predominant in this series (59 %). Infectious disease physicians initially recommended carbapenems at the beginning of the current research period, which gradually changed over time favoring the use of cefmetazole instead (p = 0.002). Cefmetazole may be safely given to patients with bacteremia caused by ESBL-producers as a definitive therapy, if one can select out relatively stable patients.

EFSA BIOHAZ Panel (EFSA Panel on Biological Hazards), 2013. Scientific Opinion on Carbapenem resistance in food animal ecosystems

DEFF Research Database (Denmark)

Hald, Tine; Baggesen, Dorte Lau

-1-encoding genes were located on IncHI2 plasmids. A methodology including selective culture is proposed for the detection of CP strains of Enterobacteriaceae and Acinetobacter spp. The choice of selective media for the surveillance of carbapenem resistance for testing animal and food samples needs...... and effective option. As genes encoding carbapenemase production are mostly plasmid-mediated, and co-resistance may be an important issue in the spread of such resistance mechanisms, decreasing the frequency of use of antimicrobials in animal production in the EU in accordance with prudent use guidelines......Carbapenems are broad-spectrum β-lactam antimicrobials used for the treatment of serious infections in humans. To date only sporadic studies have reported the occurrence of carbapenemase-producing (CP) bacteria in food-producing animals and their environment. The bacteria and enzymes isolated...

Reduction in Fluoroquinolone Use following Introduction of Ertapenem into a Hospital Formulary Is Associated with Improvement in Susceptibility of Pseudomonas aeruginosa to Group 2 Carbapenems: a 10-Year Study▿

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Cook, Paul P.; Gooch, Michael; Rizzo, Shemra

2011-01-01

We examined the effect of the addition of ertapenem to our hospital formulary on the resistance of nosocomial Pseudomonas aeruginosa to group 2 carbapenems (imipenem, meropenem, and doripenem). This was a retrospective, observational study conducted between 1 January 2000 and 31 January 2009 at a large, tertiary-care hospital. Autoregressive integrated moving average (ARIMA) regression models were used to evaluate the effect of ertapenem use on the susceptibility of Pseudomonas aeruginosa to group 2 carbapenems as well as on the use of the group 2 carbapenems, ciprofloxacin, and other antipseudomonal drugs (i.e., tobramycin, cefepime, and piperacillin-tazobactam). Resistance was expressed as a percentage of total isolates as well as the number of carbapenem-resistant bacterial isolates per 10,000 patient days. Pearson correlation was used to assess the relationship between antibiotic use and carbapenem resistance. Following the addition of ertapenem to the formulary, there was a statistically significant decrease in the percentage of Pseudomonas aeruginosa isolates resistant to the group 2 carbapenems (P = 0.003). Group 2 carbapenem use and the number of carbapenem-resistant Pseudomonas aeruginosa isolates per 10,000 patient days did not change significantly over the time period. There was a large decrease in the use of ciprofloxacin (P = 0.0033), and there was a correlation of ciprofloxacin use with the percentage of isolates resistant to the group 2 carbapenems (ρ = 0.47, P = 0.002). We suspect that the improvement in susceptibility of Pseudomonas aeruginosa to group 2 carbapenems was related to a decrease in ciprofloxacin use. PMID:21968357

Reduction in fluoroquinolone use following introduction of ertapenem into a hospital formulary is associated with improvement in susceptibility of Pseudomonas aeruginosa to group 2 carbapenems: a 10-year study.

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Cook, Paul P; Gooch, Michael; Rizzo, Shemra

2011-12-01

We examined the effect of the addition of ertapenem to our hospital formulary on the resistance of nosocomial Pseudomonas aeruginosa to group 2 carbapenems (imipenem, meropenem, and doripenem). This was a retrospective, observational study conducted between 1 January 2000 and 31 January 2009 at a large, tertiary-care hospital. Autoregressive integrated moving average (ARIMA) regression models were used to evaluate the effect of ertapenem use on the susceptibility of Pseudomonas aeruginosa to group 2 carbapenems as well as on the use of the group 2 carbapenems, ciprofloxacin, and other antipseudomonal drugs (i.e., tobramycin, cefepime, and piperacillin-tazobactam). Resistance was expressed as a percentage of total isolates as well as the number of carbapenem-resistant bacterial isolates per 10,000 patient days. Pearson correlation was used to assess the relationship between antibiotic use and carbapenem resistance. Following the addition of ertapenem to the formulary, there was a statistically significant decrease in the percentage of Pseudomonas aeruginosa isolates resistant to the group 2 carbapenems (P = 0.003). Group 2 carbapenem use and the number of carbapenem-resistant Pseudomonas aeruginosa isolates per 10,000 patient days did not change significantly over the time period. There was a large decrease in the use of ciprofloxacin (P = 0.0033), and there was a correlation of ciprofloxacin use with the percentage of isolates resistant to the group 2 carbapenems (ρ = 0.47, P = 0.002). We suspect that the improvement in susceptibility of Pseudomonas aeruginosa to group 2 carbapenems was related to a decrease in ciprofloxacin use.

Genomic Analysis of Hospital Plumbing Reveals Diverse Reservoir of Bacterial Plasmids Conferring Carbapenem Resistance

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Rebecca A. Weingarten

2018-02-01

Full Text Available The hospital environment is a potential reservoir of bacteria with plasmids conferring carbapenem resistance. Our Hospital Epidemiology Service routinely performs extensive sampling of high-touch surfaces, sinks, and other locations in the hospital. Over a 2-year period, additional sampling was conducted at a broader range of locations, including housekeeping closets, wastewater from hospital internal pipes, and external manholes. We compared these data with previously collected information from 5 years of patient clinical and surveillance isolates. Whole-genome sequencing and analysis of 108 isolates provided comprehensive characterization of blaKPC/blaNDM-positive isolates, enabling an in-depth genetic comparison. Strikingly, despite a very low prevalence of patient infections with blaKPC-positive organisms, all samples from the intensive care unit pipe wastewater and external manholes contained carbapenemase-producing organisms (CPOs, suggesting a vast, resilient reservoir. We observed a diverse set of species and plasmids, and we noted species and susceptibility profile differences between environmental and patient populations of CPOs. However, there were plasmid backbones common to both populations, highlighting a potential environmental reservoir of mobile elements that may contribute to the spread of resistance genes. Clear associations between patient and environmental isolates were uncommon based on sequence analysis and epidemiology, suggesting reasonable infection control compliance at our institution. Nonetheless, a probable nosocomial transmission of Leclercia sp. from the housekeeping environment to a patient was detected by this extensive surveillance. These data and analyses further our understanding of CPOs in the hospital environment and are broadly relevant to the design of infection control strategies in many infrastructure settings.

EFFECT OF ENDOSPERM HARDNESS ON AN ETHANOL PROCESS USING A GRANULAR STARCH HYDROLYZING ENZYME

Energy Technology Data Exchange (ETDEWEB)

Wang, P; W Liu, D B; Johnston, K D; Rausch, S J; Schmidt, M E; Tumbleson, V Singh

2010-01-01

Granular starch hydrolyzing enzymes (GSHE) can hydrolyze starch at low temperature (32°C). The dry grind process using GSHE (GSH process) has fewer unit operations and no changes in process conditions (pH 4.0 and 32°C) compared to the conventional process because it dispenses with the cooking and liquefaction step. In this study, the effects of endosperm hardness, protease, urea, and GSHE levels on GSH process were evaluated. Ground corn, soft endosperm, and hard endosperm were processed using two GSHE levels (0.1 and 0.4 mL per 100 g ground material) and four treatments of protease and urea addition. Soft and hard endosperm materials were obtained by grinding and sifting flaking grits from a dry milling pilot plant; classifications were confirmed using scanning electron microscopy. During 72 h of simultaneous granular starch hydrolysis and fermentation (GSHF), ethanol and glucose profiles were determined using HPLC. Soft endosperm resulted in higher final ethanol concentrations compared to ground corn or hard endosperm. Addition of urea increased final ethanol concentrations for soft and hard endosperm. Protease addition increased ethanol concentrations and fermentation rates for soft endosperm, hard endosperm, and ground corn. The effect of protease addition on ethanol concentrations and fermentation rates was most predominant for soft endosperm, less for hard endosperm, and least for ground corn. Samples (soft endosperm, hard endosperm, or corn) with protease resulted in higher (1.0% to 10.5% v/v) ethanol concentration compared to samples with urea. The GSH process with protease requires little or no urea addition. For fermentation of soft endosperm, GSHE dose can be reduced. Due to nutrients (lipids, minerals, and soluble proteins) present in corn that enhance yeast growth, ground corn fermented faster at the beginning than hard and soft endosperm.

Comprehensive Genome Analysis of Carbapenemase-Producing Enterobacter spp.: New Insights into Phylogeny, Population Structure, and Resistance Mechanisms.

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Chavda, Kalyan D; Chen, Liang; Fouts, Derrick E; Sutton, Granger; Brinkac, Lauren; Jenkins, Stephen G; Bonomo, Robert A; Adams, Mark D; Kreiswirth, Barry N

2016-12-13

Knowledge regarding the genomic structure of Enterobacter spp., the second most prevalent carbapenemase-producing Enterobacteriaceae, remains limited. Here we sequenced 97 clinical Enterobacter species isolates that were both carbapenem susceptible and resistant from various geographic regions to decipher the molecular origins of carbapenem resistance and to understand the changing phylogeny of these emerging and drug-resistant pathogens. Of the carbapenem-resistant isolates, 30 possessed bla KPC-2 , 40 had bla KPC-3 , 2 had bla KPC-4 , and 2 had bla NDM-1 Twenty-three isolates were carbapenem susceptible. Six genomes were sequenced to completion, and their sizes ranged from 4.6 to 5.1 Mbp. Phylogenomic analysis placed 96 of these genomes, 351 additional Enterobacter genomes downloaded from NCBI GenBank, and six newly sequenced type strains into 19 phylogenomic groups-18 groups (A to R) in the Enterobacter cloacae complex and Enterobacter aerogenes Diverse mechanisms underlying the molecular evolutionary trajectory of these drug-resistant Enterobacter spp. were revealed, including the acquisition of an antibiotic resistance plasmid, followed by clonal spread, horizontal transfer of bla KPC -harboring plasmids between different phylogenomic groups, and repeated transposition of the bla KPC gene among different plasmid backbones. Group A, which comprises multilocus sequence type 171 (ST171), was the most commonly identified (23% of isolates). Genomic analysis showed that ST171 isolates evolved from a common ancestor and formed two different major clusters; each acquiring unique bla KPC -harboring plasmids, followed by clonal expansion. The data presented here represent the first comprehensive study of phylogenomic interrogation and the relationship between antibiotic resistance and plasmid discrimination among carbapenem-resistant Enterobacter spp., demonstrating the genetic diversity and complexity of the molecular mechanisms driving antibiotic resistance in this

Novel carbapenem antibiotics for parenteral and oral applications: in vitro and in vivo activities of 2-aryl carbapenems and their pharmacokinetics in laboratory animals.

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Fujimoto, Koichi; Takemoto, Koji; Hatano, Kazuo; Nakai, Toru; Terashita, Shigeyuki; Matsumoto, Masahiro; Eriguchi, Yoshiro; Eguchi, Ken; Shimizudani, Takeshi; Sato, Kimihiko; Kanazawa, Katsunori; Sunagawa, Makoto; Ueda, Yutaka

2013-02-01

SM-295291 and SM-369926 are new parenteral 2-aryl carbapenems with strong activity against major causative pathogens of community-acquired infections such as methicillin-susceptible Staphylococcus aureus, Streptococcus pneumoniae (including penicillin-resistant strains), Streptococcus pyogenes, Enterococcus faecalis, Klebsiella pneumoniae, Moraxella catarrhalis, Haemophilus influenzae (including β-lactamase-negative ampicillin-resistant strains), and Neisseria gonorrhoeae (including ciprofloxacin-resistant strains), with MIC(90)s of ≤ 1 μg/ml. Unlike tebipenem (MIC(50), 8 μg/ml), SM-295291 and SM-369926 had no activity against hospital pathogens such as Pseudomonas aeruginosa (MIC(50), ≥ 128 μg/ml). The bactericidal activities of SM-295291 and SM-369926 against penicillin-resistant S. pneumoniae and β-lactamase-negative ampicillin-resistant H. influenzae were equal or superior to that of tebipenem and greater than that of cefditoren. The therapeutic efficacies of intravenous administrations of SM-295291 and SM-369926 against experimentally induced infections in mice caused by penicillin-resistant S. pneumoniae and β-lactamase-negative ampicillin-resistant H. influenzae were equal or superior to that of tebipenem and greater than that of cefditoren, respectively, reflecting their in vitro activities. SM-295291 and SM-369926 showed intravenous pharmacokinetics similar to those of meropenem in terms of half-life in monkeys (0.4 h) and were stable against human dehydropeptidase I. SM-368589 and SM-375769, which are medoxomil esters of SM-295291 and SM-369926, respectively, showed good oral bioavailability in rats, dogs, and monkeys (4.2 to 62.3%). Thus, 2-aryl carbapenems are promising candidates that show an ideal broad spectrum for the treatment of community-acquired infections, including infections caused by penicillin-resistant S. pneumoniae and β-lactamase-negative ampicillin-resistant H. influenzae, have low selective pressure on antipseudomonal

Trends in carbapenemase-producing Enterobacteriaceae, France, 2012 to 2014

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Dortet, Laurent; Cuzon, Gaëlle; Ponties, Valérie; Nordmann, Patrice

2017-01-01

In 2014, a total of 2,976 Enterobacteriaceae isolates with decreased susceptibility to carbapenems were received at the French Associated National Reference Center for Antibiotic Resistance (NRC) and were characterised for their molecular resistance mechanism to carbapenems and compared with results obtained during 2012 and 2013.The overall number of enterobacterial isolates with decreased susceptibility to carbapenems received at the NRC rapidly increased (more than twofold in two years) with a growing proportion of carbapenemase producers (23.1% in 2012 vs 28.6% in 2013 vs 36.2% in 2014). Between 2012 and 2014, the main carbapenemase type was OXA-48, with an increase in OXA-48 variants (mostly OXA-181) and NDM producers, whereas the number KPC producers decreased. We identified a potential spread of OXA-181 producers in the tropical region of Africa. Finally, OXA-48 and OXA-48-related enzymes remained the predominant carbapenemases in France. The number of carbapenemase-producing Escherischia coli isolates was multiplied by fivefold between 2012 and 2014, suggesting a possible dissemination in the community. PMID:28205502

Klebsiella pneumoniae Carbapenemase-2 (KPC-2, Substitutions at Ambler Position Asp179, and Resistance to Ceftazidime-Avibactam: Unique Antibiotic-Resistant Phenotypes Emerge from β-Lactamase Protein Engineering

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Melissa D. Barnes

2017-10-01

Full Text Available The emergence of Klebsiella pneumoniae carbapenemases (KPCs, β-lactamases that inactivate “last-line” antibiotics such as imipenem, represents a major challenge to contemporary antibiotic therapies. The combination of ceftazidime (CAZ and avibactam (AVI, a potent β-lactamase inhibitor, represents an attempt to overcome this formidable threat and to restore the efficacy of the antibiotic against Gram-negative bacteria bearing KPCs. CAZ-AVI-resistant clinical strains expressing KPC variants with substitutions in the Ω-loop are emerging. We engineered 19 KPC-2 variants bearing targeted mutations at amino acid residue Ambler position 179 in Escherichia coli and identified a unique antibiotic resistance phenotype. We focus particularly on the CAZ-AVI resistance of the clinically relevant Asp179Asn variant. Although this variant demonstrated less hydrolytic activity, we demonstrated that there was a prolonged period during which an acyl-enzyme intermediate was present. Using mass spectrometry and transient kinetic analysis, we demonstrated that Asp179Asn “traps” β-lactams, preferentially binding β-lactams longer than AVI owing to a decreased rate of deacylation. Molecular dynamics simulations predict that (i the Asp179Asn variant confers more flexibility to the Ω-loop and expands the active site significantly; (ii the catalytic nucleophile, S70, is shifted more than 1.5 Å and rotated more than 90°, altering the hydrogen bond networks; and (iii E166 is displaced by 2 ÅÅ when complexed with ceftazidime. These analyses explain the increased hydrolytic profile of KPC-2 and suggest that the Asp179Asn substitution results in an alternative complex mechanism leading to CAZ-AVI resistance. The future design of novel β-lactams and β-lactamase inhibitors must consider the mechanistic basis of resistance of this and other threatening carbapenemases.

Impact of enzyme loading on the efficacy and recovery of cellulolytic enzymes immobilized on enzymogel nanoparticles.

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Samaratunga, Ashani; Kudina, Olena; Nahar, Nurun; Zakharchenko, Andrey; Minko, Sergiy; Voronov, Andriy; Pryor, Scott W

2015-03-01

Cellulase and β-glucosidase were adsorbed on a polyacrylic acid polymer brush grafted on silica nanoparticles to produce enzymogels as a form of enzyme immobilization. Enzyme loading on the enzymogels was increased to a saturation level of approximately 110 μg (protein) mg(-1) (particle) for each enzyme. Enzymogels with varied enzyme loadings were then used to determine the impact on hydrolysis rate and enzyme recovery. Soluble sugar concentrations during the hydrolysis of filter paper and Solka-Floc with the enzymogels were 45 and 53%, respectively, of concentrations when using free cellulase. β-Glucosidase enzymogels showed lower performance; hydrolyzate glucose concentrations were just 38% of those using free enzymes. Increasing enzyme loading on the enzymogels did not reduce net efficacy for cellulase and improved efficacy for β-glucosidase. The use of free cellulases and cellulase enzymogels resulted in hydrolyzates with different proportions of cellobiose and glucose, suggesting differential attachment or efficacy of endoglucanases, exoglucanases, and β-glucosidases present in cellulase mixtures. When loading β-glucosidase individually, higher enzyme loadings on the enzymogels produced higher hydrolyzate glucose concentrations. Approximately 96% of cellulase and 66 % of β-glucosidase were recovered on the enzymogels, while enzyme loading level did not impact recovery for either enzyme.

Multidrug-Resistant CTX-M-(15, 9, 2)- and KPC-2-Producing Enterobacter hormaechei and Enterobacter asburiae Isolates Possessed a Set of Acquired Heavy Metal Tolerance Genes Including a Chromosomal sil Operon (for Acquired Silver Resistance).

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Andrade, Leonardo N; Siqueira, Thiago E S; Martinez, Roberto; Darini, Ana Lucia C

2018-01-01

Bacterial resistance to antibiotics is concern in healthcare-associated infections. On the other hand, bacterial tolerance to other antimicrobials, like heavy metals, has been neglected and underestimated in hospital pathogens. Silver has long been used as an antimicrobial agent and it seems to be an important indicator of heavy metal tolerance. To explore this perspective, we searched for the presence of acquired silver resistance genes ( sil operon: silE, silS, silR, silC, silF, silB, silA , and silP ) and acquired extended-spectrum cephalosporin and carbapenem resistance genes ( bla CTX-M and bla KPC ) in Enterobacter cloacae Complex (EcC) ( n = 27) and Enterobacter aerogenes ( n = 8) isolated from inpatients at a general hospital. Moreover, the genetic background of the silA (silver-efflux pump) and the presence of other acquired heavy metal tolerance genes, pcoD (copper-efflux pump), arsB (arsenite-efflux pump), terF (tellurite resistance protein), and merA (mercuric reductase) were also investigated. Outstandingly, 21/27 (78%) EcC isolates harbored silA gene located in the chromosome. Complete sil operon was found in 19/21 silA -positive EcC isolates. Interestingly, 8/20 (40%) E. hormaechei and 5/6 (83%) E. asburiae co-harbored silA/pcoD genes and bla CTX-M-(15,2,or9) and/or bla KPC-2 genes. Frequent occurrences of arsB, terF , and merA genes were detected, especially in silA/pcoD -positive, multidrug-resistant (MDR) and/or CTX-M-producing isolates. Our study showed co-presence of antibiotic and heavy metal tolerance genes in MDR EcC isolates. In our viewpoint, there are few studies regarding to bacterial heavy metal tolerance and we call attention for more investigations and discussion about this issue in different hospital pathogens.

Spread of carbapenem-resistant Acinetobacter baumannii global clone 2 in Asia and AbaR-type resistance islands.

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Kim, Dae Hun; Choi, Ji-Young; Kim, Hae Won; Kim, So Hyun; Chung, Doo Ryeon; Peck, Kyong Ran; Thamlikitkul, Visanu; So, Thomas Man-Kit; Yasin, Rohani M D; Hsueh, Po-Ren; Carlos, Celia C; Hsu, Li Yang; Buntaran, Latre; Lalitha, M K; Song, Jae-Hoon; Ko, Kwan Soo

2013-11-01

In this surveillance study, we identified the genotypes, carbapenem resistance determinants, and structural variations of AbaR-type resistance islands among carbapenem-resistant Acinetobacter baumannii (CRAB) isolates from nine Asian locales. Clonal complex 92 (CC92), corresponding to global clone 2 (GC2), was the most prevalent in most Asian locales (83/108 isolates; 76.9%). CC108, or GC1, was a predominant clone in India. OXA-23 oxacillinase was detected in CRAB isolates from most Asian locales except Taiwan. blaOXA-24 was found in CRAB isolates from Taiwan. AbaR4-type resistance islands, which were divided into six subtypes, were identified in most CRAB isolates investigated. Five isolates from India, Malaysia, Singapore, and Hong Kong contained AbaR3-type resistance islands. Of these, three isolates harbored both AbaR3- and AbaR4-type resistance islands simultaneously. In this study, GC2 was revealed as a prevalent clone in most Asian locales, with the AbaR4-type resistance island predominant, with diverse variants. The significance of this study lies in identifying the spread of global clones of carbapenem-resistant A. baumannii in Asia.

Kinetic and mass transfer studies on the isomerization of cellulose hydrolyzate using immobilized Streptomyces cells

Energy Technology Data Exchange (ETDEWEB)

Ghose, T K; Chand, S

1978-01-01

Streptomyces cells possessing glucose isomerase activity, heat-treated and confined within polyester sacs have been used in batch/continuous isomerization of enzymatically hydrolyzed microcrystalline cellulose. Conversion data at different concentrations of substrate closely follow the reactor performance equation based on the reaction kinetics. The effect of external film and pore diffusional resistances were experimentally found to be negligible. The dispersion effects in the packed bed column have been evaluated by pulse input tracer analysis. Continuous operation of the column to isomerize cellulose hydrolyzate (2.0 M glucose) showed an exponential deactivation of enzyme activity with a half-life of 447 h.

Chromobacterium spp. harbour Ambler class A β-lactamases showing high identity with KPC.

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Gudeta, Dereje Dadi; Bortolaia, Valeria; Jayol, Aurélie; Poirel, Laurent; Nordmann, Patrice; Guardabassi, Luca

2016-06-01

The origin of KPC is unknown. The aim of this study was to detect progenitors of KPC in silico and to functionally verify their β-lactam hydrolysis activity. The sequence of KPC-2 was used to mine the NCBI protein sequence database. The best non-KPC hits were analysed by amino acid (aa) alignment and phylogenetic tree construction. Genes encoding KPC-2 homologues were expressed in Escherichia coli. The carbapenemase activities of the recombinant strains were characterized by the CarbaNP test and UV spectrophotometry and MICs of selected β-lactams were determined. Genes encoding the closest KPC-2 homologues were identified on the chromosome of Chromobacterium piscinae strain ND17 (CRP-1, 76% aa identity), Chromobacterium sp. C-61 (CRS-1, 70% aa identity) and Chromobacterium haemolyticum DSM19808 (CRH-1, 69% aa identity). All three Chromobacterium β-lactamases were phylogenetically more related to KPC than to other Ambler class A β-lactamases. The 27 bp region preceding the start codon of blaCRP-1 displayed high nucleotide identity to the corresponding region upstream from blaKPC (74%). Heterologous expression of blaCRP-1 and to a lesser extent of blaCRH-1 in E. coli significantly increased the MICs of meropenem and most cephalosporins. The CarbaNP test was positive for both recombinant strains, but spectrophotometric analysis confirmed higher carbapenemase activity for CRP-1-producing clones. The recovery of three class A β-lactamases with up to 76% aa identity to KPC from distinct Chromobacterium species is highly indicative of the role played by this genus in the evolution of KPC. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Evaluation of meat, fruit and vegetables from retail stores in five United Kingdom regions as sources of extended-spectrum beta-lactamase (ESBL)-producing and carbapenem-resistant Escherichia coli.

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Randall, L P; Lodge, M P; Elviss, N C; Lemma, F L; Hopkins, K L; Teale, C J; Woodford, N

2017-01-16

We determined the prevalence and types of extended-spectrum β-lactamase (ESBL)-producing and carbapenem-resistant Escherichia coli in raw retail beef, chicken, pork, fruit and vegetables in five UK regions in 2013-14. Raw meat (n=397), and fruit and vegetable samples (n=400) were purchased from retail stores in London, East Anglia, North West England, Scotland and Wales. Samples were tested for the presence of ESBL-producing E. coli by plating enriched samples on CHROMagar CTX and CHROMagar ESBL, for AmpC-type E. coli by plating on "CHROMagar FOX" (CHROMagar ECC+16mg/L cefoxitin), and for carbapenem-resistant E. coli by plating on CHROMagar KPC. Additionally, pre-enrichment counts were performed on the above agars, and on CHROMagar ECC. Isolates of interest were characterised by MALDI-ToF to confirm identification, by PCR for bla CIT, bla CTX-M, bla OXA , bla SHV and bla TEM genes; ESBL or bla CIT genes were sequenced. Only 1.9% and 2.5% of beef and pork samples, respectively were positive for ESBL-producing E. coli after enrichment compared with 65.4% of chicken samples. 85.6% positive samples from chicken meat carried bla CTX-M-1 ; bla CTX-M-15 was not detected. None of the fruits or vegetables yielded ESBL-producing E. coli and none of the meat, fruit or vegetable samples yielded carbapenem-resistant E. coli. Retail chicken was more frequently a source of ESBL-producing E. coli than were beef, pork, fruit or vegetables. None of the foodstuffs yielded E. coli with CTX-M-15 ESBL, which dominates in human clinical isolates in the UK, and none yielded carbapenem-resistant E. coli. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Management of KPC-producing Klebsiella pneumoniae infections.

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Bassetti, M; Giacobbe, D R; Giamarellou, H; Viscoli, C; Daikos, G L; Dimopoulos, G; De Rosa, F G; Giamarellos-Bourboulis, E J; Rossolini, G M; Righi, E; Karaiskos, I; Tumbarello, M; Nicolau, D P; Viale, P L; Poulakou, G

2018-02-01

Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae (KPC-KP) has become one of the most important contemporary pathogens, especially in endemic areas. To provide practical suggestion for physicians dealing with the management of KPC-KP infections in critically ill patients, based on expert opinions. PubMed search for relevant publications related to the management of KPC-KP infections. A panel of experts developed a list of 12 questions to be addressed. In view of the current lack of high-level evidence, they were asked to provide answers on the bases of their knowledge and experience in the field. The panel identified several key aspects to be addressed when dealing with KPC-KP in critically ill patients (preventing colonization in the patient, preventing infection in the colonized patient and colonization of his or her contacts, reducing mortality in the infected patient by rapidly diagnosing the causative agent and promptly adopting the best therapeutic strategy) and provided related suggestions that were based on the available observational literature and the experience of panel members. Diagnostic technologies could speed up the diagnosis of KPC-KP infections. Combination treatment should be preferred to monotherapy in cases of severe infections. For non-critically ill patients without severe infections, results from randomized clinical trials are needed for ultimately weighing benefits and costs of using combinations rather than monotherapy. Multifaceted infection control interventions are needed to decrease the rates of colonization and cross-transmission of KPC-KP. Copyright © 2017 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Enhancing polyphenol extraction from unripe apples by carbohydrate-hydrolyzing enzymes*

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Zheng, Hu-zhe; Hwang, In-Wook; Chung, Shin-Kyo

2009-01-01

The effects of process variables such as enzyme types, enzyme ratio, reaction temperature, pH, time, and ethanol concentration on the extraction of unripe apple polyphenol were investigated. The results indicated that Viscozyme L had the strongest effect on polyphenols extraction and was selected to study the polyphenol composition. The ratio of enzyme (Viscozyme L) to substrate (2 fungal beta-glucanase units (FBG)) at 0.02, reaction at pH 3.7, 50 °C for 12 h, and ethanol concentration of 70% were chosen as the most favorable extraction condition. Total phenolic content (TPC), reducing sugar content (RSC), and extraction yield increased by about 3, 1.5, and 2 times, respectively, compared with control. The contents of p-coumaric acid, ferulic acid, and caffeic acid increased to 8, 4, and 32 times, respectively. The enzyme-aided polyphenol extraction process from unripe apples might be applied to food industry for enhancing bioactive compound production. PMID:19946955

Enhancing polyphenol extraction from unripe apples by carbohydrate-hydrolyzing enzymes.

Science.gov (United States)

Zheng, Hu-zhe; Hwang, In-Wook; Chung, Shin-Kyo

2009-12-01

The effects of process variables such as enzyme types, enzyme ratio, reaction temperature, pH, time, and ethanol concentration on the extraction of unripe apple polyphenol were investigated. The results indicated that Viscozyme L had the strongest effect on polyphenols extraction and was selected to study the polyphenol composition. The ratio of enzyme (Viscozyme L) to substrate (2 fungal beta-glucanase units (FBG)) at 0.02, reaction at pH 3.7, 50 degrees C for 12 h, and ethanol concentration of 70% were chosen as the most favorable extraction condition. Total phenolic content (TPC), reducing sugar content (RSC), and extraction yield increased by about 3, 1.5, and 2 times, respectively, compared with control. The contents of p-coumaric acid, ferulic acid, and caffeic acid increased to 8, 4, and 32 times, respectively. The enzyme-aided polyphenol extraction process from unripe apples might be applied to food industry for enhancing bioactive compound production.

Antimicrobial activity of tempeh gembus hydrolyzate

Science.gov (United States)

Noviana, A.; Dieny, F. F.; Rustanti, N.; Anjani, G.; Afifah, D. N.

2018-02-01

Tropical disease can be prevented by consumming fermented foods that have antimicrobial activity. One of them is tempeh gembus that has short shelf life. It can be overcome by processing it into hydrolyzate. This study aimed to determine antimicrobial activity of tempeh gembus hydrolyzate. Tempeh gembus was made of local soybean from Grobogan. They were added 5,000 ppm, 8,000 ppm, and 10,000 ppm of bromelain enzyme (TGH BE). Antimicrobial effects of TGH BE were tested against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Steptococcus mutans. Antimicrobial test was carried out using Kirby-Bauer Disc Diffussion method. Soluble protein test used Bradford method. The largest inhibition zone against S. aureus and S. mutans were shown by TGH BE 8,000 ppm, 0.89±0.53 mm and 2.40±0.72 mm. The largest inhibition zone of B. subtilis, 7.33±2,25 mm, was shown by TGH BE 5,000 ppm. There wasn’t antimicrobial effect of TGH BE against E. coli. There weren’t significant differences of soluble protein (P=0.293) and the inhibition zones againt S. aureus (P = 0.967), E. coli (P = 1.000), B. subtilis (P = 0.645), S. mutans (P=0.817) of all treatments. There were antimicrobial activities of TGH BE against S. aureus, B. subtilis, and S. mutans.

Expanding the Repertoire of Carbapenem-Hydrolyzing Metallo-ß-Lactamases by Functional Metagenomic Analysis of Soil Microbiota

DEFF Research Database (Denmark)

Gudeta, Dereje D.; Bortolaia, Valeria; Pollini, Simona

2016-01-01

as metallo-beta-lactamases (MBLs), were identified in six soil samples, including two subclass B1 (GRD23-1 and SPN79-1) and seven subclass B3 (CRD3-1, PEDO-1, GRD33-1, ESP-2, ALG6-1, ALG11-1, and DHT2-1). Except PEDO-1 and ESP-2, these enzymes were distantly related to any previously described MBLs (33 to 59......% identity). RAIphy analysis indicated that six enzymes (CRD3-1, GRD23-1, DHT2-1, SPN79-1, ALG6-1, and ALG11-1) originated from Proteobacteria, two (PEDO-1 and ESP-2) from Bacteroidetes and one (GRD33-1) from Gemmatimonadetes. All MBLs detected in soil microbiota were functional when expressed in E. coli...

Compliance with carbapenem guidelines in a university hospital.

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Van Hollebeke, M; Chapuis, C; Bernard, S; Foroni, L; Stahl, J P; Bedouch, P; Pavese, P

2016-03-01

We aimed to evaluate carbapenem prescription compliance with guidelines for nosocomial and community-acquired infections. We conducted a prospective study over a four-month period at our university hospital. We included all adult and pediatric hospitalized patients who had received at least one dose of carbapenem. Data was collected from patients' medical records (hard copy and computerized data; CristalLink software). Compliance with guidelines was assessed by two infectious disease specialists. Assessment criteria included indication, antibiotic choice, dosage, and treatment duration. We included 152 patients in the study (65.4% of men). Carbapenem prescription was appropriate for 76.3% of prescriptions. The use of carbapenems was considered appropriate for 73.9% of empirical prescriptions and for 77.8% of documented prescriptions. Non-compliance with guidelines was mainly due to prescriptions for community-acquired infections. Antibiotic de-escalation could not be initiated in 40.3% of patients and was only initiated in 51.7% of patients for whom it could be considered. Although the average treatment duration was 7.5 days, 23.7% of patients received carbapenems for more than 10 days. These results highlight the need for a strong carbapenem stewardship program in our hospital. Copyright © 2016. Published by Elsevier SAS.

Construction of a hybrid β-hexosaminidase subunit capable of forming stable homodimers that hydrolyze GM2 ganglioside in vivo

Directory of Open Access Journals (Sweden)

Michael B Tropak

2016-01-01

Full Text Available Tay-Sachs or Sandhoff disease result from mutations in either the evolutionarily related HEXA or HEXB genes encoding respectively, the α- or β-subunits of β-hexosaminidase A (HexA. Of the three Hex isozymes, only HexA can interact with its cofactor, the GM2 activator protein (GM2AP, and hydrolyze GM2 ganglioside. A major impediment to establishing gene or enzyme replacement therapy based on HexA is the need to synthesize both subunits. Thus, we combined the critical features of both α- and β-subunits into a single hybrid µ-subunit that contains the α-subunit active site, the stable β-subunit interface and unique areas in each subunit needed to interact with GM2AP. To facilitate intracellular analysis and the purification of the µ-homodimer (HexM, CRISPR-based genome editing was used to disrupt the HEXA and HEXB genes in a Human Embryonic Kidney 293 cell line stably expressing the µ-subunit. In association with GM2AP, HexM was shown to hydrolyze a fluorescent GM2 ganglioside derivative both in cellulo and in vitro. Gene transfer studies in both Tay-Sachs and Sandhoff mouse models demonstrated that HexM expression reduced brain GM2 ganglioside levels.

Construction of a hybrid β-hexosaminidase subunit capable of forming stable homodimers that hydrolyze GM2 ganglioside in vivo

Science.gov (United States)

Tropak, Michael B; Yonekawa, Sayuri; Karumuthil-Melethil, Subha; Thompson, Patrick; Wakarchuk, Warren; Gray, Steven J; Walia, Jagdeep S; Mark, Brian L; Mahuran, Don

2016-01-01

Tay-Sachs or Sandhoff disease result from mutations in either the evolutionarily related HEXA or HEXB genes encoding respectively, the α- or β-subunits of β-hexosaminidase A (HexA). Of the three Hex isozymes, only HexA can interact with its cofactor, the GM2 activator protein (GM2AP), and hydrolyze GM2 ganglioside. A major impediment to establishing gene or enzyme replacement therapy based on HexA is the need to synthesize both subunits. Thus, we combined the critical features of both α- and β-subunits into a single hybrid µ-subunit that contains the α-subunit active site, the stable β-subunit interface and unique areas in each subunit needed to interact with GM2AP. To facilitate intracellular analysis and the purification of the µ-homodimer (HexM), CRISPR-based genome editing was used to disrupt the HEXA and HEXB genes in a Human Embryonic Kidney 293 cell line stably expressing the µ-subunit. In association with GM2AP, HexM was shown to hydrolyze a fluorescent GM2 ganglioside derivative both in cellulo and in vitro. Gene transfer studies in both Tay-Sachs and Sandhoff mouse models demonstrated that HexM expression reduced brain GM2 ganglioside levels. PMID:26966698

THE MASS PROFILE OF THE GALAXY TO 80 kpc

International Nuclear Information System (INIS)

Gnedin, Oleg Y.; Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J.

2010-01-01

The Hypervelocity Star Survey presents the currently largest sample of radial velocity measurements of halo stars out to 80 kpc. We apply spherical Jeans modeling to these data in order to derive the mass profile of the Galaxy. We restrict the analysis to distances larger than 25 kpc from the Galactic center, where the density profile of halo stars is well approximated by a single power law with logarithmic slope between -3.5 and -4.5. With this restriction, we also avoid the complication of modeling a flattened Galactic disk. In the range 25 kpc c (80 kpc) lies between 175 and 231 km s -1 , with the most likely value of 193 km s -1 . Compared with the value at the solar location, the Galactic circular velocity declines by less than 20% over an order of magnitude in radius. Such a flat profile requires a massive and extended dark matter halo. The mass enclosed within 80 kpc is 6.9 +3.0 -1.2 x 10 11 M sun . Our sample of radial velocities is large enough that the biggest uncertainty in the mass is not statistical but systematic, dominated by the density slope and anisotropy of the tracer population. Further progress requires modeling observed data sets within realistic simulations of galaxy formation.

Predominance of carbapenem-resistant Pseudomonas aeruginosa isolates carrying blaIMP and blaVIM metallo-β-lactamases in a major hospital in Costa Rica.

Science.gov (United States)

Toval, Francisco; Guzmán-Marte, Anel; Madriz, Vivian; Somogyi, Teresita; Rodríguez, César; García, Fernando

2015-01-01

This study aimed to assess the molecular basis of the resistance to carbapenems in clinical isolates of Pseudomonas aeruginosa recovered from a tertiary-level health facility in San José, Costa Rica. A total of 198 non-duplicated isolates were evaluated for their susceptibility to β-lactams, aminoglycosides and fluoroquinolones. The production of metallo-β-lactamases (MBLs), the presence of MBL encoding genes (blaIMP, blaVIM and blaGIM-1) and the occurrence of these genes within class 1 integrons were investigated. In addition, an ERIC2 PCR fingerprinting method was used to elucidate the distribution of the detected MBL genes within the strain collection. Of the 198 isolates tested, 125 (63.1 %) were categorized as carbapenem-resistant. The majority (88.8 %) of the carbapemen-resistant isolates also showed resistance to ceftazidime, cefepime, aztreonam, ticarcillin/clavulanic acid, amikacin, gentamicin, tobramycin, ciprofloxacin and gatifloxacin. Among the carbapenem-resistant isolates, 102 (81.6 %) showed MBL activity. Strikingly, both blaIMP and blaVIM genes were simultaneously detected in most (94.1 %) of the 102 MBL producers. Five carbapenem-resistant MBL producers were positive only for blaIMP genes. Almost 70 % of the isolates examined harboured the intI1 gene, accompanied by the sul1 and qacEΔ1 genes in 136 (99 %) and 122 (89 %) isolates, respectively. The majority (94.4 %) of the carbapenem-resistant isolates carried the intI1 gene, in contrast to 26 % of the carbapenem-susceptible isolates. Ninety-three out of 96 (96.9 %) isolates carrying both blaIMP and blaVIM genes also harboured the intI1, sul1 and qacEΔ1 genes. Gene cassettes from carbapenem-susceptible and MBL-negative carbapenem-resistant isolates encoded aminoglycoside-resistance enzymes (aadA2, aadA4 and aadA6) as well as orfD and qacF genes. RAPD analysis distributed 126 of the isolates in 29 clusters. Eighty of the 90 blaIMP (+) blaVIM (+) isolates were sorted into 16

Transrectal ultrasound-guided biopsy sepsis and the rise in carbapenem antibiotic use.

Science.gov (United States)

Leahy, Olivia R; O'Reilly, Mary; Dyer, David R; Phillips, David; Grummet, Jeremy P

2015-12-01

This study sought to determine the number of hospital admissions for sepsis following transrectal ultrasound-guided (TRUS) biopsy, and the rate of both prophylactic and therapeutic use of carbapenem antibiotics for TRUS biopsy, at a single institution. A retrospective review of prospectively collected data from the medical records electronic database of Cabrini Health, a private metropolitan hospital, was queried for coding of admissions under any admitting urologist for sepsis and prostate-related infections from 2009 to 2012. Records were examined for whether a TRUS biopsy had been performed within 14 days prior and if a therapeutic carbapenem was required. The database also queried the use of carbapenems as prophylaxis in patients undergoing TRUS biopsy. Of the 63 admissions for TRUS biopsy sepsis, multi-drug-resistant organisms were isolated from 26 (41%). Twenty-three admissions were from the 1937 patients who underwent a TRUS biopsy at Cabrini (a sepsis rate of 1.2%) and 40 were following TRUS biopsies at other centres. Thirty-seven (58.7%) patients received therapeutic carbapenems either empirically, or after culture results. Of the 1937 Cabrini TRUS biopsy patients, 154 (8%) were given a carbapenem as prophylaxis, with a rapid increase in prophylactic use over the 4 years studied from 0.25% to 13%. This study did not show evidence of an increasing rate of hospital admissions for TRUS biopsy sepsis at this institution. However, there was a dramatic uptake in prophylactic administration of carbapenems. Increasing carbapenem use may contribute to development of carbapenem-resistant bacteria. Alternative methods of prostate biopsy that avoid sepsis should be considered. © 2014 Royal Australasian College of Surgeons.

Inactivation of Mycobacterium tuberculosis l,d-Transpeptidase LdtMt1 by Carbapenems and Cephalosporins

Science.gov (United States)

Dubée, Vincent; Triboulet, Sébastien; Mainardi, Jean-Luc; Ethève-Quelquejeu, Mélanie; Gutmann, Laurent; Marie, Arul; Dubost, Lionel

2012-01-01

The structure of Mycobacterium tuberculosis peptidoglycan is atypical since it contains a majority of 3→3 cross-links synthesized by l,d-transpeptidases that replace 4→3 cross-links formed by the d,d-transpeptidase activity of classical penicillin-binding proteins. Carbapenems inactivate these l,d-transpeptidases, and meropenem combined with clavulanic acid is bactericidal against extensively drug-resistant M. tuberculosis. Here, we used mass spectrometry and stopped-flow fluorimetry to investigate the kinetics and mechanisms of inactivation of the prototypic M. tuberculosis l,d-transpeptidase LdtMt1 by carbapenems (meropenem, doripenem, imipenem, and ertapenem) and cephalosporins (cefotaxime, cephalothin, and ceftriaxone). Inactivation proceeded through noncovalent drug binding and acylation of the catalytic Cys of LdtMt1, which was eventually followed by hydrolysis of the resulting acylenzyme. Meropenem rapidly inhibited LdtMt1, with a binding rate constant of 0.08 μM−1 min−1. The enzyme was unable to recover from this initial binding step since the dissociation rate constant of the noncovalent complex was low (carbapenem side chains affected both the binding and acylation steps, ertapenem being the most efficient LdtMt1 inactivator. Cephalosporins also formed covalent adducts with LdtMt1, although the acylation reaction was 7- to 1,000-fold slower and led to elimination of one of the drug side chains. Comparison of kinetic constants for drug binding, acylation, and acylenzyme hydrolysis indicates that carbapenems and cephems can both be tailored to optimize peptidoglycan synthesis inhibition in M. tuberculosis. PMID:22615283

Similarity of hydrolyzing activity of human and rat small intestinal disaccharidases

Directory of Open Access Journals (Sweden)

Oku T

2011-06-01

Full Text Available Tsuneyuki Oku¹, Kenichi Tanabe¹, Shigeharu Ogawa², Naoki Sadamori¹, Sadako Nakamura¹¹Graduate School of Human Health Science, University of Nagasaki, Siebold, Nagayo, Japan; ²Juzenkai Hospital, Kagomachi, Nagasaki, JapanBackground: The purpose of this study was to clarify whether it is possible to extrapolate results from studies of the hydrolyzing activity of disaccharidases from rats to humans.Materials and methods: We measured disaccharidase activity in humans and rats using identical preparation and assay methods, and investigated the similarity in hydrolyzing activity. Small intestinal samples without malignancy were donated by five patients who had undergone bladder tumor surgery, and homogenates were prepared to measure disaccharidase activity. Adult rat homogenates were prepared using small intestine.Results: Maltase activity was the highest among the five disaccharidases, followed by sucrase and then palatinase in humans and rats. Trehalase activity was slightly lower than that of palatinase in humans and was similar to that of sucrase in rats. Lactase activity was the lowest in humans, but was similar to that of palatinase in rats. Thus, the hydrolyzing activity of five disaccharidases was generally similar in humans and rats. The relative activity of sucrose and palatinase versus maltase was generally similar between humans and rats. The ratio of rat to human hydrolyzing activity of maltase, sucrase, and palatinase was 1.9–3.1, but this was not a significant difference. Leaf extract from Morus alba strongly inhibited the activity of maltase, sucrase, and palatinase, but not trehalase and lactase, and the degree of inhibition was similar in humans and rats. L-arabinose mildly inhibited sucrase activity, but hardly inhibited the activity of maltase, palatinase, trehalase and lactase in humans and rats. The digestibility of 1-kestose, galactosylsucrose, and panose by small intestinal enzymes was very similar between humans and

Kinetic properties of two Rhizopus exo-polygalacturonase enzymes hydrolyzing galacturonic acid oligomers using isothermal titration calorimetry

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The kinetic characteristics of two Rhizopus oryzae exo-polygalacturonases acting on galacturonic acid oligomers (GalpA) were determined using isothermal titration calorimetry (ITC). RPG15 hydrolyzing (GalpA)2 demonstrated a Km of 55 uM and kcat of 10.3 s^-1^ while RPG16 was shown to have greater af...

Clinical and Epidemiological Significance of Carbapenem Resistance in Acinetobacter baumannii Infections.

Science.gov (United States)

Tal-Jasper, Ruthy; Katz, David E; Amrami, Nadav; Ravid, Dor; Avivi, Dori; Zaidenstein, Ronit; Lazarovitch, Tsilia; Dadon, Mor; Kaye, Keith S; Marchaim, Dror

2016-05-01

Carbapenems are considered the treatment of choice for Acinetobacter baumannii infections. Many facilities implement preventive measures toward only carbapenem-resistant A. baumannii (CRAB). However, the independent role of the carbapenem resistance determinant on patient outcomes remains controversial. In a 6-year analysis of adults with A. baumannii bloodstream infection (BSI), the outcomes of 149 CRAB isolates were compared to those of 91 patients with carbapenem-susceptible A. baumannii In bivariable analyses, CRAB BSIs were significantly associated with worse outcomes and with a delay in the initiation of appropriate antimicrobial therapy (DAAT). However, in multivariable analyses, carbapenem resistance status was no longer associated with poor outcomes, while DAAT remained an independent predictor. The epidemiological significance of A. baumannii should not be determined by its resistance to carbapenems. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

A prospective study of treatment of carbapenem-resistant Enterobacteriaceae infections and risk factors associated with outcome.

Science.gov (United States)

de Maio Carrilho, Claudia M D; de Oliveira, Larissa Marques; Gaudereto, Juliana; Perozin, Jamile S; Urbano, Mariana Ragassi; Camargo, Carlos H; Grion, Cintia M C; Levin, Anna Sara S; Costa, Silvia F

2016-11-03

To describe the clinical and microbiological data of carbapenem-resistant Enterobacteriaceae (CRE) infections, the treatment used, hospital- and infection-related mortality, and risk factors for death. A prospective cohort conducted from March 2011 to December 2012. Clinical, demographic, and microbiological data such as in vitro sensitivity, clonality, carbapenemase gene mortality related to infection, and overall mortality were evaluated. Data were analyzed using Epi Info version 7.0 (CDC, Atlanta, GA, USA) and SPSS (Chicago, IL, USA). One hundred and twenty-seven patients were evaluated. Pneumonia, 52 (42 %), and urinary tract infections (UTI), 51 (40.2 %), were the most frequent sites of infection. The isolates were polyclonal; the Bla KPC gene was found in 75.6 % of isolates, and 27 % of isolates were resistant to colistin. Mortality related to infection was 34.6 %, and was higher among patients with pneumonia (61.4 %). Combination therapy was used in 98 (77.2 %), and monotherapy in 22.8 %; 96.5 % of them were UTI patients. Shock, age, and dialysis were independent risk factors for death. There was no difference in infection-related death comparing colistin-susceptible and colistin-resistant infections (p = 0.46); neither in survival rate comparing the use of combination therapy with two drugs or more than two drugs (p = 0.32). CRE infection mortality was higher among patients with pneumonia. Infections caused by colistin-resistant isolates did not increase mortality. The use of more than two drugs on combination therapy did not show a protective effect on outcome. The isolates were polyclonal, and the bla KPC gene was the only carbapenemase found. Shock, dialysis, and age over 60 years were independent risk factors for death.

Carbapenem Breakpoints for Acinetobacter baumannii Group: Supporting Clinical Outcome Data from Patients with Bacteremia.

Science.gov (United States)

Lee, Yi-Tzu; Chiang, Mei-Chun; Kuo, Shu-Chen; Wang, Yung-Chih; Lee, I-Hsin; Chen, Te-Li; Yang, Ya-Sung

2016-01-01

The carbapenem breakpoints set by different organizations for Acinetobacter are discordant, but supporting clinical data are lacking. This study aimed to provide the first clinical outcome data to support the carbapenem breakpoints for Acinetobacter baumannii (Ab) group in patients with bacteremia. This study included 117 adults who received carbapenems for treatment of Ab group bacteremia in Taipei Veterans General Hospital over an 8-year period. We analyzed 30-day mortality rates among patient groups acquiring isolates with different carbapenem minimal inhibitory concentrations (MICs). The carbapenem MIC breakpoint derived from classification and regression tree (CART) analysis to delineate the risk of 30-day mortality was between MICs of ≤ 4 mg/L and ≥ 8 mg/L. Mortality rate was higher in patients acquiring isolates with carbapenem MIC ≥ 8 mg/L than ≤ 4 mg/L, by bivariate (54.9% [28/51] vs 25.8% [17/66]; P = 0.003) and survival analysis (P = 0.001 by log-rank test). Multivariate analysis using logistic regression and Cox regression models including severity of illness indices demonstrated that treating patients with Ab group bacteremia caused by isolates with a carbapenem MIC ≥ 8 mg/L with carbapenem was an independent predictor of 30-day mortality (odds ratio, 5.125; 95% confidence interval [CI], 1.946-13.498; P = 0.001, and hazard ratio, 2.630; 95% CI, 1.431-4.834; P = 0.002, respectively). The clinical outcome data confirmed that isolates with MIC ≤ 4 mg/L were susceptible to carbapenem, and those with MIC ≥ 8 mg/L were resistant in patients with Ab group bacteremia.

KPC-PRODUCING Serratia marcescens IN A HOME-CARE PATIENT FROM RECIFE, BRAZIL.

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Margate, Emmily; Magalhães, Vera; Fehlberg, Lorena Cristina Corrêa; Gales, Ana Cristina; Lopes, Ana Catarina Souza

2015-01-01

In this brief communication we describe the occurrence of a KPC-producing Serratia marcescens isolate in a home-care patient from Recife, Brazil. The blaKPC, blaSPM, blaIMP, blaVIM, blaOXA, blaCTX-M, blaSHV, blaTEM and blaGES genes were investigated by Polymerase Chain Reaction (PCR) and DNA sequencing. The isolate was positive for blaKPC-2 and blaTEM-1 and was resistant to aztreonam, cefepime, cefotaxime, imipenem, meropenem, gentamicin, ciprofloxacin and cefazidime, and susceptible only to amikacin, tigecycline and gatifloxacin. This is the first report in Brazil of KPC-producing S. marcescens clinical isolate outside of a hospital environment. Caregivers should be alert for the presence of this isolate in the community setting.

Enhanced Glucose Uptake in Human Liver Cells and Inhibition of Carbohydrate Hydrolyzing Enzymes by Nordic Berry Extracts

Directory of Open Access Journals (Sweden)

Giang Thanh Thi Ho

2017-10-01

Full Text Available A Western lifestyle with low physical activity and a diet rich in sugar, fat and processed food contribute to higher incidences of diabetes and obesity. Enhanced glucose uptake in human liver cells was observed after treatment with phenolic extracts from different Nordic berries. All berry extracts showed higher inhibition against α-amylase and α-glucosidase than the anti-diabetic agent acarbose. Total phenolic content and phenolic profiles in addition to antioxidant activities, were also investigated. The berries were extracted with 80% methanol on an accelerated solvent extraction system (ASE and then purified by C-18 solid phase extraction (SPE. Among the ASE methanol extracts, black chokeberry, crowberry and elderberry extracts showed high stimulation of glucose uptake in HepG2 cells and also considerable inhibitory effect towards carbohydrate hydrolyzing enzymes. SPE extracts with higher concentrations of phenolics, resulted in increased glucose uptake and enhanced inhibition of α-amylase and α-glucosidase compared to the ASE extracts. Crowberry and cloudberry were the most potent 15-lipoxygenase inhibitors, while bog whortleberry and lingonberry were the most active xanthine oxidase inhibitors. These results increase the value of these berries as a component of a healthy Nordic diet and have a potential benefit against diabetes.

The Evaluation of Dipeptidyl Peptidase (DPP)-IV, α-Glucosidase and Angiotensin Converting Enzyme (ACE) Inhibitory Activities of Whey Proteins Hydrolyzed with Serine Protease Isolated from Asian Pumpkin (Cucurbita ficifolia).

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Konrad, Babij; Anna, Dąbrowska; Marek, Szołtysik; Marta, Pokora; Aleksandra, Zambrowicz; Józefa, Chrzanowska

2014-01-01

In the present study, whey protein concentrate (WPC-80) and β-lactoglobulin were hydrolyzed with a noncommercial serine protease isolated from Asian pumpkin ( Cucurbita ficifolia ). Hydrolysates were further fractionated by ultrafiltration using membranes with cut-offs equal 3 and 10 kDa. Peptide fractions of molecular weight lower than 3 and 3-10 kDa were further subjected to the RP-HPLC. Separated preparations were investigated for their potential as the natural inhibitors of dipeptidyl peptidase (DPP-IV), α-glucosidase and angiotensin converting enzyme (ACE). WPC-80 hydrolysate showed higher inhibitory activities against the three tested enzymes than β-lactoglobulin hydrolysate. Especially high biological activities were exhibited by peptide fractions of molecular weight lower than 3 kDa, with ACE IC50 food ingredients in the diet of patients with type 2 diabetes.

Molecular mechanisms associated with nosocomial carbapenem-resistant Acinetobacter baumannii in Mexico.

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Alcántar-Curiel, María Dolores; García-Torres, Luis Francisco; González-Chávez, María Inés; Morfín-Otero, Rayo; Gayosso-Vázquez, Catalina; Jarillo-Quijada, Ma Dolores; Fernández-Vázquez, José Luis; Giono-Cerezo, Silvia; Rodríguez-Noriega, Eduardo; Santos-Preciado, José Ignacio

2014-10-01

Acinetobacter baumannii is an emerging pathogen worldwide that is most commonly associated with nosocomial infections and multi-drug resistance. In the present study we determined the mechanisms of carbapenem resistance and clonal diversity of A. baumannii nosocomial isolates in Hospital Civil de Guadalajara, Mexico. A total of 303 clinical isolates of A. baumannii identified during a period expanding from 2004-2011 were analyzed for carbapenem resistance using several microbiological and molecular methods. Clonal relatedness of these isolates was determined using pulsed-field gel electrophoresis. Of the 303 isolates, 84% were resistant to meropenem, 71.3% to imipenem and 78.3% the resistant isolates were positive for metallo-β-lactamases as determined by the phenotypic assay. In addition, 49.6% of carbapenem-intermediate or -resistant isolates carried the blaOXA-72 gene and 1.2% carried the blaVIM-1 gene. Efflux pump phenotype was responsible for reduced susceptibility to meropenem in 14.5% and to imipenem in 31.6% of the resistant isolates, respectively in the presence of the efflux pump inhibitor, carbonyl cyanide 3-chlorophenylhydrazone. Strains representing different carbapenem-resistant patterns exhibited reduced expression of 22, 29, 33, and 43 kDa OMPs. Among the bacterial collection studied, 48 different clones were identified, two of which were predominant and persistently transmitted. Carbapenemase production in combination with efflux pump expression, reduction in OMPs expression and the cross-transmission of clones appear to be major contributors to the high frequency of carbapenem-resistance observed in A. baumannii. To our knowledge, this is the first study to define the molecular mechanisms associated with carbapenem-resistance in A. baumannii in Mexico. Copyright © 2014 IMSS. Published by Elsevier Inc. All rights reserved.

Effects of Carbapenem consumption on the prevalence of Acinetobacter infection in intensive care unit patients.

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Ogutlu, Aziz; Guclu, Ertugrul; Karabay, Oguz; Utku, Aylin Calica; Tuna, Nazan; Yahyaoglu, Mehmet

2014-01-09

The consumption of carbapenems has increased worldwide, together with the increase in resistant gram negative bacilli. Subsequently, the prevalence of carbapenem-resistant Acinetobacter infections has increased rapidly and become a significant problem particularly in intensive care unit patients. The aim of the present study was to evaluate the changes in the prevalence of Acinetobacter infection by restricting the consumption of carbapenems in intensive care unit patients. This study was conducted between May 1, 2011 and February 28, 2013. The amount of carbapenem consumption and the number of patients with multi-drug resistant Acinetobacter baumannii (MDRAB) isolates during the study period were retrospectively obtained from the records of the patients, who were hospitalized in the intensive care unit. The study period was divided into two periods named as: Carbapenem non-restricted period (CNRP) and carbapenem-restricted period (CRP). During CNRP, no restrictions were made on the use of carbapenems. During CRP, the use of carbapenems was not allowed if there was an alternative to carbapenems. Primary Endpoint: MDRAB infection after ICU admission. The definition of nosocomial infections related to Acinetobacter spp. was based on the criteria of the Center for Disease Control (CDC). The correlation between the amount of carbapenem consumption and the number of infections with MDRAB strains between the two periods were evaluated. During the study period, a total of 1822 patients' (1053 patients in CNRP and 769 patients in CRP) records were evaluated retrospectively. A total of 10.82 defined daily dose (DDD/100 ICU days) of anti-pseudomonal carbapenem were used in CNRP, and this figure decreased to 6.95 DDD/100 ICU days in CRP. In the 8-month CNRP, 42 (3.98%) MDRAB-related nosocomial infections were detected, and 14 (1.82%) infections were detected in CRP (p = 0.012). The prevalence of MDRAB strains isolated in the CNRP was 2.24-fold higher than the prevalence in

Widespread increase of empirical carbapenem use in acute care hospitals in Catalonia, Spain.

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Grau, Santiago; Fondevilla, Esther; Echeverría-Esnal, Daniel; Alcorta, Amaia; Limon, Enric; Gudiol, Francesc

2018-04-24

The overall increase in the use of carbapenems could lead to the selection of carbapenem-resistant bacteria. The objectives of this study were to analyze carbapenem use from 2008 to 2015 and their prescription profile in 58 hospitals affiliated to the VINCat Programme (nosocomial infection vigilance system). Retrospective, longitudinal and descriptive study of carbapenem use. Consecutive case-series study, looking for carbapenem prescription characteristics, conducted in January 2016. Use was calculated in defined daily doses (DDD)/100 patient-days (PD); prescription profiles were assessed using a standardized survey. Carbapenem use increased 88.43%, from 3.37 DDD/100-PD to 6.35 DDD/100-PD (pCatalonia. Stewardship interventions are required to prevent carbapenem overuse. Copyright © 2018 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Low Prevalence of Carbapenem-Resistant Bacteria in River Water: Resistance Is Mostly Related to Intrinsic Mechanisms.

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Tacão, Marta; Correia, António; Henriques, Isabel S

2015-10-01

Carbapenems are last-resort antibiotics to handle serious infections caused by multiresistant bacteria. The incidence of resistance to these antibiotics has been increasing and new resistance mechanisms have emerged. The dissemination of carbapenem resistance in the environment has been overlooked. The main goal of this research was to assess the prevalence and diversity of carbapenem-resistant bacteria in riverine ecosystems. The presence of frequently reported carbapenemase-encoding genes was inspected. The proportion of imipenem-resistant bacteria was on average 2.24 CFU/ml. Imipenem-resistant strains (n=110) were identified as Pseudomonas spp., Stenotrophomonas maltophilia, Aeromonas spp., Chromobacterium haemolyticum, Shewanella xiamenensis, and members of Enterobacteriaceae. Carbapenem-resistant bacteria were highly resistant to other beta-lactams such as quinolones, aminoglycosides, chloramphenicol, tetracyclines, and sulfamethoxazole/trimethoprim. Carbapenem resistance was mostly associated with intrinsically resistant bacteria. As intrinsic resistance mechanisms, we have identified the blaCphA gene in 77.3% of Aeromonas spp., blaL1 in all S. maltophilia, and blaOXA-48-like in all S. xiamenensis. As acquired resistance mechanisms, we have detected the blaVIM-2 gene in six Pseudomonas spp. (5.45%). Integrons with gene cassettes encoding resistance to aminoglycosides (aacA and aacC genes), trimethoprim (dfrB1b), and carbapenems (blaVIM-2) were found in Pseudomonas spp. Results suggest that carbapenem resistance dissemination in riverine ecosystems is still at an early stage. Nevertheless, monitoring these aquatic compartments for the presence of resistance genes and its host organisms is essential to outline strategies to minimize resistance dissemination.

Antibodies from the sera of HIV-infected patients efficiently hydrolyze all human histones.

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Baranova, Svetlana V; Buneva, Valentina N; Nevinsky, Georgy A

2016-08-01

Histones and their post-translational modifications have key roles in chromatin remodeling and gene transcription. Besides intranuclear functions, histones act as damage-associated molecular pattern molecules when they are released into the extracellular space. Administration of exogenous histones to animals leads to systemic inflammatory and toxic responses through activating Toll-like receptors and inflammasome pathways. Here, using ELISA it was shown that sera of HIV-infected patients and healthy donors contain autoantibodies against histones. Autoantibodies with enzymic activities (abzymes) are a distinctive feature of autoimmune diseases. It was interesting whether antibodies from sera of HIV-infected patients can hydrolyze human histones. Electrophoretically and immunologically homogeneous IgGs were isolated from sera of HIV-infected patients by chromatography on several affinity sorbents. We present first evidence showing that 100% of IgGs purified from the sera of 32 HIV-infected patients efficiently hydrolyze from one to five human histones. Several rigid criteria have been applied to show that the histone-hydrolyzing activity is an intrinsic property of IgGs of HIV-infected patients. The relative efficiency of hydrolysis of histones (H1, H2a, H2b, H3, and H4) significantly varied for IgGs of different patients. IgGs from the sera of 40% of healthy donors also hydrolyze histones but with an average efficiency approximately 16-fold lower than that of HIV-infected patients. Similar to proteolytic abzymes from the sera of patients with several autoimmune diseases, histone-hydrolyzing IgGs from HIV-infected patients were inhibited by specific inhibitors of serine and of metal-dependent proteases, but an unexpected significant inhibition of the activity by specific inhibitor of thiol-like proteases was also observed. Because IgGs can efficiently hydrolyze histones, a negative role of abzymes in development of acquired immune deficiency syndrome cannot be

Wastewater as a Source of Carbapenem Resistant Escherichia coli

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Clinical studies have reported that the occurrence of carbapenem resistant E. coli is on the rise. This is of concern because carbapenem antibiotics are typically reserved for treating infections caused by bacteria resistant to other classes of antibiotics. Current literature st...

Chemical and proteolysis-derived changes during long-term storage of lactose-hydrolyzed ultrahigh-temperature (UHT) milk.

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Jansson, Therese; Jensen, Hanne B; Sundekilde, Ulrik K; Clausen, Morten R; Eggers, Nina; Larsen, Lotte B; Ray, Colin; Andersen, Henrik J; Bertram, Hanne C

2014-11-19

Proteolytic activity in milk may release bitter-tasting peptides and generate free amino terminals that react with carbohydrates, which initiate Maillard reaction. Ultrahigh temperature (UHT) heat treatment inactivates the majority of proteolytic enzymes in milk. In lactose-hydrolyzed milk a β-galactosidase preparation is applied to the milk after heat treatment, which has proteolytic side activities that may induce quality deterioration of long-term-stored milk. In the present study proteolysis, glycation, and volatile compound formation were investigated in conventional (100% lactose), filtered (60% lactose), and lactose-hydrolyzed (<1% lactose) UHT milk using reverse phase high-pressure liquid chromatography-mass spectrometry, proton nuclear magnetic resonance, and gas chromatography-mass spectrometry. Proteolysis was observed in all milk types. However, the degree of proteolysis was significantly higher in the lactose-hydrolyzed milk compared to the conventional and filtered milk. The proteins most prone to proteolysis were β-CN and αs1-CN, which were clearly hydrolyzed after approximately 90 days of storage in the lactose-hydrolyzed milk.

Activity of MK-7655 combined with imipenem against Enterobacteriaceae and Pseudomonas aeruginosa.

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Livermore, David M; Warner, Marina; Mushtaq, Shazad

2013-10-01

MK-7655 is a novel inhibitor of class A and C β-lactamases. We investigated its potential to protect imipenem. Chequerboard MICs were determined by CLSI agar dilution: (i) for Enterobacteriaceae with carbapenemases; (ii) for Enterobacteriaceae with carbapenem resistance contingent on combinations of impermeability together with an extended-spectrum β-lactamase or AmpC enzyme; and (iii) for Pseudomonas aeruginosa and other non-fermenters. At a concentration of 4 mg/L, MK-7655 reduced imipenem MICs for Enterobacteriaceae with KPC carbapenemases from 16-64 mg/L to 0.12-1 mg/L. Synergy also was seen for Enterobacteriaceae with impermeability-mediated carbapenem resistance, with weaker synergy seen for isolates with the OXA-48 enzyme. On the other hand, MK-7655 failed to potentiate imipenem against Enterobacteriaceae with metallo-carbapenemases. In the case of P. aeruginosa, where endogenous AmpC confers slight protection versus imipenem, 4 mg/L MK-7655 reduced the MIC of imipenem for all isolates, except those with metallo-carbapenemases: the MICs of imipenem fell from 1-2 mg/L to 0.25-0.5 mg/L for imipenem-susceptible P. aeruginosa and from 16-64 mg/L to 1-4 mg/L for OprD-deficient strains. No potentiation was seen for chryseobacteria or for Stenotrophomonas maltophilia. MK-7655 potentiated imipenem against Enterobacteriaceae with KPC carbapenemases or combinations of β-lactamase and impermeability, but not those with metallo-carbapenemases. It augmented the activity of imipenem against P. aeruginosa in general and OprD mutants in particular.

Selection and production of insoluble xylan hydrolyzing enzyme by ...

African Journals Online (AJOL)

Jane

2011-03-07

Mar 7, 2011 ... The effect of pH and temperature on the enzyme activity and stability of crude enzyme produced by T. lanuginosus THKU 56 were investigated. To study the effect of pH on activity, the reaction mixture of 0.5 ml of enzyme and 0.5 ml of 1% insoluble oat spelt xylan in 50 mM buffers with various pH values ...

Outbreak of carbapenem-resistant Providencia rettgeri in a tertiary ...

African Journals Online (AJOL)

Carbapenem resistance in Enterobacteriaceae is often plasmid mediated, necessitating stringent infection control practices. We describe an outbreak of carbapenem-resistant Providencia rettgeri involving 4 patients admitted to intensive care and high-care units at a tertiary hospital. Clinical and demographic characteristics ...

Treatment Options for Infections Caused by Carbapenem-resistant Enterobacteriaceae: Can We Apply “Precision Medicine” to Antimicrobial Chemotherapy?

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Perez, Federico; El Chakhtoura, Nadim G.; Papp-Wallace, Krisztina; Wilson, Brigid M; Bonomo, Robert A.

2016-01-01

Introduction For the past three decades, carbapenems played a central role in our antibiotic armamentarium, trusted to effectively treat infections caused by drug-resistant bacteria. The utility of this class of antibiotics has been compromised by the emergence of resistance especially among Enterobacteriaceae. Areas covered We review the current mainstays of pharmacotherapy against infections caused by carbapenem-resistant Enterobacteriaceae (CRE) including tigecycline, aminoglycosides, and rediscovered 'old' antibiotics such as fosfomycin and polymyxins, and discuss their efficacy and potential toxicity. We also summarize the clinical experience treating CRE infections with antibiotic combination therapy. Finally, we review ceftazidime/avibactam and imipenem/relebactam, a new generation of beta-lactamase inhibitors, which may offer alternatives to treat CRE infections. We critically evaluate the published literature, identify relevant clinical trials and review documents submitted to the United States Food and Drug Administration. Expert Opinion It is essential to define the molecular mechanisms of resistance and to apply insights about pharmacodynamic and pharmacokinetic properties of antibiotics, in order to maximize the impact of old and new therapeutic approaches against infections caused by CRE. A concerted effort is needed to carry out high-quality clinical trials that: i) establish the superiority of combination therapy vs. monotherapy; ii) confirm the role of novel beta-lactam/beta-lactamase inhibitor combinations as therapy against KPC- and OXA-48 producing Enterobacteriaceae; and, iii) evaluate new antibiotics active against CRE as they are introduced into the clinic. PMID:26799840

Impact of carbapenem heteroresistance among clinical isolates of invasive Escherichia coli in Chongqing, southwestern China.

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Sun, J D; Huang, S F; Yang, S S; Pu, S L; Zhang, C M; Zhang, L P

2015-05-01

Although heteroresistance is common in a wide range of microorganisms, carbapenem heteroresistance among invasive Escherichia coli infections has not been reported. The objective of this study was to evaluate the clinical significance of carbapenem heteroresistance and to identify risk factors for its acquisition. A case-control study was conducted at a 3200-bed teaching hospital in Chongqing, southwestern China. Successive and non-duplicate nosocomial E. coli isolates (n = 332) were obtained from July 2011 to June 2013. Bloodstream isolates made up 50.6% of the strains collected. The rates of heteroresistance were 25.0% to imipenem, 17.2% to ertapenem, and 3.9% to meropenem. The population analysis profile revealed the presence of subpopulations with higher carbapenem resistance, showing MICs ranging from 2.0-128.0mg/L. Male gender, invasive intervention, antibiotic use and bacterial extended-spectrum β-lactamase (ESBL) production contributed to invasive infections by carbapenem-heteroresistant E. coli (CHEC). The production of ESBL was identified as the common independent risk factor for heteroresistance to both ertapenem and imipenem. Pulsed-field gel electrophoresis revealed clonal diversity among the CHEC isolates. Most importantly, characterization of two successive E. coli strains isolated from the same patient indicated that carbapenem resistance evolved from heteroresistance. In conclusion, the high prevalence of heteroresistance to carbapenem among invasive E. coli merits great attention. Routine detection of ESBLs and the prudent use of imipenem and ertapenem are advocated. The early targeted intervention should be formulated to reduce CHEC infection and carbapenem resistance of E. coli. Copyright © 2014 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

The rapid spread of carbapenem-resistant Enterobacteriaceae

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Potter, Robert F.; D’Souza, Alaric W.; Dantas, Gautam

2016-01-01

Carbapenems, our one-time silver bullet for multidrug resistant bacterial infections, are now threatened by widespread dissemination of carbapenem-resistant Enterobacteriaceae (CRE). Successful expansion of Enterobacteriaceae clonal groups and frequent horizontal gene transfer of carbapenemase expressing plasmids are causing increasing carbapenem resistance. Recent advances in genetic and phenotypic detection facilitate global surveillance of CRE diversity and prevalence. In particular, whole genome sequencing enabled efficient tracking, annotation, and study of genetic elements colocalized with carbapenemase genes on chromosomes and on plasmids. Improved characterization helps detail the co-occurrence of other antibiotic resistance genes in CRE isolates and helps identify pan-drug resistance mechanisms. The novel β-lactamase inhibitor, avibactam, combined with ceftazidime or aztreonam, is a promising CRE treatment compared to current colistin or tigecycline regimens. To halt increasing CRE-associated morbidity and mortality, we must continue quality, cooperative monitoring and urgently investigate novel treatments. PMID:27912842

Pharmacodynamics of colistin and fosfomycin: a 'treasure trove' combination combats KPC-producing Klebsiella pneumoniae.

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Zhao, Miao; Bulman, Zackery P; Lenhard, Justin R; Satlin, Michael J; Kreiswirth, Barry N; Walsh, Thomas J; Marrocco, Amanda; Bergen, Phillip J; Nation, Roger L; Li, Jian; Zhang, Jing; Tsuji, Brian T

2017-07-01

KPC-producing Klebsiella pneumoniae are an emerging public health problem around the globe. We defined the combinatorial pharmacodynamics and ability to suppress resistance of two 'old' antibiotics, fosfomycin and colistin, in time-kill experiments and hollow-fibre infection models (HFIM). Two KPC-2-producing K. pneumoniae isolates were used: one susceptible to both colistin and fosfomycin (KPC 9A: MIC colistin 0.25 mg/L and MIC fosfomycin ≤8 mg/L) and the other resistant to colistin and susceptible to fosfomycin (KPC 5A: MIC colistin 64 mg/L and MIC fosfomycin 32 mg/L). Time-kill experiments assessed an array of colistin and fosfomycin concentrations against both isolates. Colistin and fosfomycin pharmacokinetics from critically ill patients were simulated in the HFIM to define the pharmacodynamic activity of humanized regimens over 5 days against KPC 9A. In time-kill experiments, synergy was demonstrated for all colistin/fosfomycin combinations containing >8 mg/L fosfomycin against the double-susceptible KPC strain, 9A. Synergy versus KPC strain 5A was only achieved at the highest concentrations of colistin (4 mg/L) and fosfomycin (512 mg/L) at 48 h. In the HFIM, colistin or fosfomycin monotherapies resulted in rapid proliferation of resistant subpopulations; KPC 9A regrew by 24 h. In contrast to the monotherapies, the colistin/fosfomycin combination resulted in a rapid 6.15 log 10  cfu/mL reduction of KPC 9A by 6 h and complete suppression of resistant subpopulations until 120 h. Colistin and fosfomycin may represent an important treatment option for KPC-producing K. pneumoniae otherwise resistant to traditional antibiotics. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Correlation between carbapenem consumption and resistance to carbapenems among Enterobacteriaceae isolates collected from patients with intra-abdominal infections at five medical centers in Taiwan, 2006-2010.

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Ho, Cheng-Mao; Ho, Mao-Wang; Liu, Yung-Ching; Toh, Han-Siong; Lee, Yu-Lin; Liu, Yuag-Meng; Huang, Chi-Chang; Lu, Po-Liang; Liu, Chun-Eng; Chen, Yen-Hsu; Ko, Wen-Chien; Tang, Hung-Jen; Yu, Kwok-Woon; Chen, Yao-Shen; Chuang, Yin-Ching; Wang, Jen-Hsien; Hsueh, Po-Ren

2012-06-01

We investigated the trend in resistance to carbapenems among isolates of Enterobacteriaceae that had been collected from patients with intra-abdominal infections at five medical centers in Taiwan from 2006 to 2010 and evaluated the correlation between resistance to carbapenems and consumption of said agents as part of the Study for Monitoring Antimicrobial Resistance Trends (SMART). During the study period, the usage of ertapenem and that of total carbapenems (ertapenem, imipenem, and meropenem) increased significantly from 6.13 to 13.38 defined daily doses per 1000 patient-days for ertapenem and from 20.43 to 34.25 defined daily doses per 1000 patient-days for total carbapenems. The most common species were Escherichia coli (n = 1095), Klebsiella spp. (n = 663), and Enterobacter spp. (n = 202). The susceptibility of all isolates to ertapenem and to imipenem varied during the study period. For ertapenem, the rates of nonsusceptibility ranged from 3.5% to 10.3% and those for imipenem ranged from 3.5% to 10.7%. Although the use of carbapenems increased during the study period, there was no marked increase in resistance to carbapenems. Continuous monitoring of resistance trends is necessary so that antimicrobial prescription policies can be adjusted and infection control intervention programs can be implemented. Copyright © 2012 Elsevier B.V. All rights reserved.

Investigating of four main carbapenem-resistance mechanisms in high-level carbapenem resistant Pseudomonas aeruginosa isolated from burn patients

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Soodabeh Rostami

2018-02-01

Conclusion: Emerging antimicrobial resistance in burn wound bacterial pathogens is a serious therapeutic challenge for clinicians. In the present study, most of the isolates were MDR. This finding indicated an alarming spread of resistant isolates and suggested that infection control strategies should be considered. Resistance to carbapenems is influenced by several factors, not all of which were evaluated in our study; however, the results showed that production of MBLs and overexpression of the mexB gene were the most frequent mechanisms in carbapenem-resistant isolates.

Cellulolytic enzyme compositions and uses thereof

Energy Technology Data Exchange (ETDEWEB)

Iyer, Prashant; Gaspar, Armindo Ribiero; Croonenberghs, James; Binder, Thomas P.

2017-07-25

The present invention relates enzyme composition comprising a cellulolytic preparation and an acetylxylan esterase (AXE); and the used of cellulolytic enzyme compositions for hydrolyzing acetylated cellulosic material. Finally the invention also relates to processes of producing fermentation products from acetylated cellulosic materials using a cellulolytic enzyme composition of the invention.

Factors associated with acquisition of carbapenem-resistant Enterobacteriaceae

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Lilian Silva Lavagnoli

2017-10-01

Full Text Available ABSTRACT Objective: to identify possible risk factors for acquisition of Enterobacterial strains with a marker for resistance to carbapenems. Methods: exploratory case-control study performed in hospital settings. The study sample consisted of patients with biological specimens that tested positive for carbapenem-resistant Enterobacteriaceae (cases, with the disk diffusion test and Etest, and controls with biological samples testing negative for carbapenem-resistant Enterobacteriaceae. In all, 65 patients were included: 13 (20% cases and 52 (80% controls. Results: the microorganisms isolated were Serratia marcescens (6, Klebsiella pneumoniae (4, and Enterobacter cloacae (3. Univariate analysis revealed that length of hospitalization prior to sample collection (p=0.002 and having a surgical procedure (p=0.006 were statistically significant. In the multivariable logistic regression model, both were still significant, with odds ratios of 0.93 (p = 0.009; 95% CI: 0.89 to 0.98 for length of hospitalization prior to sample collection, and 9.28 (p = 0.05; 95% CI: 1.01 to 85.14 for having a surgical procedure. Conclusion: shorter hospitalization times and increased surveillance of patients undergoing surgery could play a decisive role in reducing the spread of carbapenem-resistant microorganisms in hospital settings.

First glycoside hydrolase family 2 enzymes from Thermus antranikianii and Thermus brockianus with β-glucosidase activity

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Carola eSchröder

2015-06-01

Full Text Available Two genes tagh2 and tbgh2 coding for enzymes with hydrolytic activity towards esculin were identified from the extreme thermophilic, aerobic bacteria Thermus antranikianii (Ta and T. brockianus (Tb. Shortened conserved domains predicted a membership of the enzymes of glycoside hydrolase (GH family 2. At present, β-galactosidase activity is found frequently in GH family 2 but β-glucosidase activity has not been reported in this family before. The enzymes TaGH2 and TbGH2 preferred hydrolysis of nitrophenol-linked β-D-glucopyranosides with specific activities of 3,966 U/mg and 660 U/mg, respectively. Residual activities of 40 % (TaGH2 and 51 % (TbGH2 towards 4-NP-β-D-galactopyranoside were observed. Furthermore, TaGH2 hydrolyzed cellobiose. TbGH2, however, showed no activity on cellobiose or lactose. The enzymes exhibited highest activity at 95 °C (TaGH2 and 90 °C (TbGH2 at pH 6.5. Both enzymes were extremely thermostable and thermal activation up to 250 % was observed at temperatures between 50 and 60 °C. Accordingly, the first thermoactive glycoside hydrolase family 2 enzymes with β glucosidase activity have been identified and characterized. The hydrolysis of cellobiose is a unique property of TaGH2 when compared to the enzymes of GH family 2.

Selected Probiotic Lactobacilli Have the Capacity To Hydrolyze Gluten Peptides during Simulated Gastrointestinal Digestion.

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Francavilla, Ruggiero; De Angelis, Maria; Rizzello, Carlo Giuseppe; Cavallo, Noemi; Dal Bello, Fabio; Gobbetti, Marco

2017-07-15

The aim of this study was to demonstrate the capacity of probiotic lactobacilli to hydrolyze immunogenic gluten peptides. Eighteen commercial strains of probiotic lactobacilli with highly variable peptidase activity (i.e., aminopeptidase N, iminopeptidase, prolyl endopeptidyl peptidase, tripeptidase, prolidase, prolinase, and dipeptidase), including toward Pro-rich peptides, were tested in this study. Ten probiotic strains were selected on the basis of their specific enzyme activity. When pooled, these 10 strains provided the peptidase portfolio that is required to completely degrade the immunogenic gluten peptides involved in celiac disease (CD). The selected probiotic mixture was able to completely hydrolyze well-known immunogenic epitopes, including the gliadin 33-mer peptide, the peptide spanning residues 57 to 68 of the α9-gliadin (α9-gliadin peptide 57-68), A-gliadin peptide 62-75, and γ-gliadin peptide 62-75. During digestion under simulated gastrointestinal conditions, the pool of 10 selected probiotic lactobacilli strongly hydrolyzed the wheat bread gluten (ca. 18,000 ppm) to less than 10 ppm after 360 min of treatment. As determined by multidimensional chromatography (MDLC) coupled to nanoelectrospray ionization (nano-ESI)-tandem mass spectrometry (MS/MS), no known immunogenic peptides were detected in wheat bread that was digested in the presence of the probiotics. Accordingly, the level of cytokines (interleukin 2 [IL-2], IL-10, and interferon gamma [IFN-γ]) produced by duodenal biopsy specimens from CD patients who consumed wheat bread digested by probiotics was similar to the baseline value (negative control). Probiotics that specifically hydrolyze gluten polypeptides could also be used to hydrolyze immunogenic peptides that contaminate gluten-free products. This could provide a new and safe adjunctive therapy alternative to the gluten-free diet (GFD). IMPORTANCE This study confirmed that probiotic Lactobacillus strains have different enzymatic

The rapid spread of carbapenem-resistant Enterobacteriaceae.

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Potter, Robert F; D'Souza, Alaric W; Dantas, Gautam

2016-11-01

Carbapenems, our one-time silver bullet for multidrug resistant bacterial infections, are now threatened by widespread dissemination of carbapenem-resistant Enterobacteriaceae (CRE). Successful expansion of Enterobacteriaceae clonal groups and frequent horizontal gene transfer of carbapenemase expressing plasmids are causing increasing carbapenem resistance. Recent advances in genetic and phenotypic detection facilitate global surveillance of CRE diversity and prevalence. In particular, whole genome sequencing enabled efficient tracking, annotation, and study of genetic elements colocalized with carbapenemase genes on chromosomes and on plasmids. Improved characterization helps detail the co-occurrence of other antibiotic resistance genes in CRE isolates and helps identify pan-drug resistance mechanisms. The novel β-lactamase inhibitor, avibactam, combined with ceftazidime or aztreonam, is a promising CRE treatment compared to current colistin or tigecycline regimens. To halt increasing CRE-associated morbidity and mortality, we must continue quality, cooperative monitoring and urgently investigate novel treatments. Copyright © 2016 Elsevier Ltd. All rights reserved.

Outbreak of carbapenem-resistant Providencia rettgeri in a tertiary hospital

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V S Tshisevhe

2017-01-01

Full Text Available The emergence of resistance to multiple antimicrobial agents in pathogenic bacteria is a significant public health threat, as there are limited effective antimicrobial agents for infections caused by multidrug-resistant (MDR bacteria. Several MDR bacteria are now frequently detected. Carbapenem resistance in Enterobacteriaceae is often plasmid mediated, necessitating stringent infection control practices. We describe an outbreak of carbapenem-resistant Providencia rettgeri involving 4 patients admitted to intensive care and high-care units at a tertiary hospital. Clinical and demographic characteristics of 4 patients with carbapenem-resistant P. rettgeri were documented. All P. rettgeri isolated in these cases had a carbapenem-resistant antibiogram, with resistance to imipenem, ertapenem and meropenem. These cases could be epidemiologically linked. A multiprong approach, simultaneously targeting antibiotic stewardship, universal precautions and appropriate transmission-based precaution practices, is integral to prevention and control of nosocomial infections.

Actividad comparativa in vitro de doripenem y de otros carbapenemes frente a Pseudomonas aeruginosa In vitro activity of doripenem and other carbapenems against Pseudomonas aeruginosa

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F. Nicola

2010-09-01

Full Text Available Según estudios previos, el nuevo carbapeneme doripenem sería más activo frente a Pseudomonas aeruginosa en comparación con otros carbapenemes. En este estudio evaluamos la actividad in vitro del doripenem, el meropenem y el imipenem frente a 93 aislamientos de P. aeruginosa mediante los métodos de dilución en agar y de difusión con discos. Las CIM50 y CIM90 de los carbapenemes fueron (μg/ml: imipenem, 4 y 8; meropenem, 2 y 8; doripenem, 2 y 4, respectivamente. El doripenem fue 1 a 3 diluciones más activo que el imipenem para un 82% de los aislamientos. Comparado con el meropenem, el doripenem fue, 1-3 diluciones más activo frente a un 50% de los aislamientos, mientras que en el 49% la CIM fue la misma. Los porcentajes de resistencia según los métodos de dilución y de difusión fueron: imipenem = 7,5%/49,5% y meropenem = 3,2%/9,7%. Para el doripenem, estos valores variaron según los puntos de corte (PC que se consideraron: 1,1%/2,2% usando el PC del CLSI para el imipenem y el meropenem, o 1,1%/17,2% según los PC sugeridos por Brown et al. El método de difusión presentó un elevado porcentaje de errores menores en la categorización de los aislamientos respecto de la dilución en agar, lo que sobrestimó la resistencia. El doripenem mostró muy buena actividad frente a P. aeruginosa, superior a la del imipenem y al menos equiparable a la del meropenem, por lo que puede considerarse una interesante opción para el tratamiento de infecciones por esta bacteria.Doripenem, a new carbapenem, has shown to be more active against Pseudomonas aeruginosa than other carbapenems. The activity of doripenem, imipenem and meropenem was evaluated against 93 P. aeruginosa isolates, by agar dilution and disk diffusion methods. MIC50 and MIC90 were as follows (μg/ml: doripenem, 2 and 4; meropenem, 2 and 8; and imipenem, 4 and 8, respectively. Doripenem MICs were 1 to 3 dilutions lower (i.e. more active than those for imipenem in 82% of the isolates

In vitro activity of tigecycline and comparators against carbapenem-susceptible and resistant Acinetobacter baumannii clinical isolates in Italy

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Carattoli Alessandra

2008-02-01

Full Text Available Abstract Background In a recent multi-centre Italian survey (2003–2004, conducted in 45 laboratories throughout Italy with the aim of monitoring microorganisms responsible for severe infections and their antibiotic resistance, Acinetobacter baumannii was isolated from various wards of 9 hospitals as one of the most frequent pathogens. One hundred and seven clinically significant strains of A. baumannii isolates were included in this study to determine the in vitro activity of tigecycline and comparator agents. Methods Tests for the susceptibility to antibiotics were performed by the broth microdilution method as recommended by CLSI guidelines. The following antibiotics were tested: aztreonam, piperacillin/tazobactam, ampicillin/sulbactam, ceftazidime, cefepime, imipenem, meropenem tetracycline, doxycycline, tigecycline, gentamicin, amikacin, ciprofloxacin, colistin, and trimethoprim/sulphametoxazole. The PCR assay was used to determine the presence of OXA, VIM, or IMP genes in the carbapenem resistant strains. Results A. baumannii showed widespread resistance to ceftazidime, ciprofloxacin and aztreonam in more than 90% of the strains; resistance to imipenem and meropenem was 50 and 59% respectively, amikacin and gentamicin were both active against about 30% of the strains and colistin about 99%, with only one strain resistant. By comparison with tetracyclines, tigecycline and doxycycline showed a higher activity. In particular, tigecycline showed a MIC90 value of 2 mg/L and our strains displayed a unimodal distribution of susceptibility being indistinctly active against carbapenem-susceptible and resistant strains, these latter possessed OXA-type variant enzymes. Conclusion In conclusion, tigecycline had a good activity against the MDR A. baumannii strains while maintaining the same MIC90 of 2 mg/L against the carbapenem-resistant strains.

Wastewater as a Source of Carbapenem-Resistant E. coli (Webinar)

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Clinical studies have reported that the occurrence of carbapenem-resistant E. coli is on the rise. This is of concern because carbapenem antibiotics are typically reserved for treating infections caused by bacteria resistant to other classes of antibiotics. Current literature st...

Understanding the synergistic effect and the main factors influencing the enzymatic hydrolyzability of corn stover at low enzyme loading by hydrothermal and/or ultrafine grinding pretreatment.

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Zhang, Haiyan; Li, Junbao; Huang, Guangqun; Yang, Zengling; Han, Lujia

2018-05-26

A thorough assessment of the microstructural changes and synergistic effects of hydrothermal and/or ultrafine grinding pretreatment on the subsequent enzymatic hydrolysis of corn stover was performed in this study. The mechanism of pretreatment was elucidated by characterizing the particle size, specific surface area (SSA), pore volume (PV), average pore size, cellulose crystallinity (CrI) and surface morphology of the pretreated samples. In addition, the underlying relationships between the structural parameters and final glucose yields were elucidated, and the relative significance of the factors influencing enzymatic hydrolyzability were assessed by principal component analysis (PCA). Hydrothermal pretreatment at a lower temperature (170 °C) combined with ultrafine grinding achieved a high glucose yield (80.36%) at a low enzyme loading (5 filter paper unit (FPU)/g substrate) which is favorable. The relative significance of structural parameters in enzymatic hydrolyzability was SSA > PV > average pore size > CrI/cellulose > particle size. PV and SSA exhibited logarithmic correlations with the final enzymatic hydrolysis yield. Copyright © 2018 Elsevier Ltd. All rights reserved.

Subcellular localization of pituitary enzymes

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Smith, R. E.

1970-01-01

A cytochemical procedure is reported for identifying subcellular sites of enzymes hydrolyzing beta-naphthylamine substrates, and to study the sites of reaction product localization in cells of various tissues. Investigations using the substrate Leu 4-methoxy-8-naphthylamine, a capture with hexonium pararosaniline, and the final chelation of osmium have identified the hydrolyzing enzyme of rat liver cells; this enzyme localized on cell membranes with intense deposition in the areas of the parcanaliculi. The study of cells in the anterior pituitary of the rat showed the deposition of reaction product on cell membrane; and on the membranes of secretion granules contained within the cell. The deposition of reaction product on the cell membrane however showed no increase or decrease with changes in the physiological state of the gland and release of secretion granules from specific cells.

Treatment and Outcome of Carbapenem-Resistant Gram-Negative Bacilli Blood-Stream Infections in a Tertiary Care Hospital.

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Shah, Pooja G; Shah, Sweta R

2015-07-01

Infections caused by carbapenem-resistant bacteria constitute a major challenge for current medical practice. To describe treatment and outcome of carbapenem-resistant Gram-negative bacilli (GNB) blood-stream infection (BSI) caused by these organisms at a tertiary care hospital in Mumbai. Carbapenem-resistant isolates from blood cultures were collected from January 2013 to April 2013. Identification and antimicrobial susceptibility testing were performed using Vitek 2 analyzer (Biomerieux Ltd.). Carbapenemase production was detected by modified Hodge's test (MHT). Patient's medical history, treatment and co-morbid conditions were noted. Outcomes of BSIs were evaluated. Forty-two isolates of carbapenem-resistant GNB isolated from BSIs were Enterobacteriaceae spp. (19), Acinetobacter baumannii (15), and Pseudomonas aeruginosa (8). Colistin had maximum in vitro activity with 97% against Enterobacteriaceae, 100% against Acinetobacter, and 100% activity against Pseudomonas aeruginosa isolates. Positivity of MHT was 92.9%. Outcome of colistin mono and combination therapy was comparable with 83% and 79%, respectively. Outcome of colistin and carbapenem combination therapy was found to be 100 percent. High incidences of bacteremia by carbapenem-resistant GNB including Enterobacteriaceae is a worrisome trend. Treatment options are compromised and only available option is colistin which has its own limitation. Colistin monotherapy may be non-inferior compared to combination therapy for treating BSIs caused by isolates with minimum inhibitory concentration (MIC) for colistin as ≤0.5 mg/l. Combined use of the colistin and carbapenem may provide good therapeutic options for BSI caused by carbapenem-resistant GNB and warrants further investigations.

Duodenoscope-Related Outbreak of a Carbapenem-Resistant Klebsiella pneumoniae Identified Using Advanced Molecular Diagnostics.

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Humphries, Romney M; Yang, Shuan; Kim, Stephen; Muthusamy, Venkatara Raman; Russell, Dana; Trout, Alisa M; Zaroda, Teresa; Cheng, Quen J; Aldrovandi, Grace; Uslan, Daniel Zachary; Hemarajata, Peera; Rubin, Zachary Aaron

2017-10-01

Carbapenem-resistant Klebsiella pneumoniae infections are increasingly prevalent in North American hospitals. We describe an outbreak of carbapenem-resistant K. pneumoniae containing the blaOXA-232 gene transmitted by contaminated duodenoscopes during endoscopic retrograde cholangiopancreatography (ERCP) procedures. An outbreak investigation was performed when 9 patients with blaOXA-232 carbapenem-resistant K. pneumoniae infections were identified at a tertiary care hospital. The investigation included 2 case-control studies, review of duodenoscope reprocessing procedures, and culture of devices. Carbapenem-resistant Enterobacteriacieae (CRE) isolates were evaluated with polymerase chain reaction analysis for carbapenemase genes, and isolates with the blaOXA-232 gene were subjected to whole-genome sequencing and chromosome single-nucleotide polymorphism analysis. On recognition of ERCP as a key risk factor for infection, targeted patient notification and CRE screening cultures were performed. Molecular testing ultimately identified 17 patients with blaOxa-232 carbapenem-resistant K. pneumoniae isolates, including 9 with infections, 7 asymptomatic carriers who had undergone ERCP, and 1 additional patient who had been hospitalized in India and was probably the initial carrier. Two case-control studies established a point-source outbreak associated with 2 specific duodenoscopes. A field investigation of the use, reprocessing, and storage of deuodenoscopes did not identify deviations from US Food and Drug Administration or manufacturer recommendations for reprocessing. This outbreak demonstrated the previously underappreciated potential for duodenoscopes to transmit disease, even after undergoing high-level disinfection according to manufacturers' guidelines.

Marine biofouling resistance of polyurethane with biodegradation and hydrolyzation.

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Xu, Wentao; Ma, Chunfeng; Ma, Jielin; Gan, Tiansheng; Zhang, Guangzhao

2014-03-26

We have prepared polyurethane with poly(ε-caprolactone) (PCL) as the segments of the main chain and poly(triisopropylsilyl acrylate) (PTIPSA) as the side chains by a combination of radical polymerization and a condensation reaction. Quartz crystal microbalance with dissipation studies show that polyurethane can degrade in the presence of enzyme and the degradation rate decreases with the PTIPSA content. Our studies also demonstrate that polyurethane is able to hydrolyze in artificial seawater and the hydrolysis rate increases as the PTIPSA content increases. Moreover, hydrolysis leads to a hydrophilic surface that is favorable to reduction of the frictional drag under dynamic conditions. Marine field tests reveal that polyurethane has good antifouling ability because polyurethane with a biodegradable PCL main chain and hydrolyzable PTIPSA side chains can form a self-renewal surface. Polyurethane was also used to carry and release a relatively environmentally friendly antifoulant, and the combined system exhibits a much higher antifouling performance even in a static marine environment.

Cloning and characterization of ginsenoside Ra1-hydrolyzing beta-D-xylosidase from Bifidobacterium breve K-110.

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Hyun, Yang-Jin; Kim, Bomi; Kim, Dong-Hyun

2012-04-01

beta-D-Xylosidase (E.C. 3.2.1.37) from Bifidobacterium breve K-110, which hydrolyzes ginsenoside Ra1 to ginsenoside Rb2, was cloned and expressed in Escherichia coli. The (His6)-tagged recombinant enzyme, designated as XlyBK- 110, was efficiently purified using Ni²⁺-affinity chromatography (109.9-fold, 84% yield). The molecular mass of XylBK- 100 was found to be 55.7 kDa by SDS-PAGE. Its sequence revealed a 1,347 bp open reading frame (ORF) encoding a protein containing 448 amino acids, which showed 82% identity (DNA) to the previously reported glycosyl hydrolase family 30 of Bifidobacterium adolescentis ATCC 15703. The Km and Vmax values toward p-nitrophenyl-beta-D-xylopyranoside (pNPX) were 1.45mM and 10.75 micromol/min/mg, respectively. This enzyme had pH and temperature optima at 6.0 and 45 degrees C, respectively. XylBK-110 acted to the greatest extent on xyloglucosyl kakkalide, followed by pNPX and ginsenoside Ra1, but did not act on p-nitrophenyl-alpha-Larabinofuranoside, p-nitrophenyl-beta-D-glucopyranoside, or p-nitrophenyl-beta-D-fucopyranoside. In conclusion, this is the first report on the cloning and expression of beta-Dxylosidase- hydrolyzing ginsenoside Ra1 and kakkalide from human intestinal microflora.

Bagasse hydrolyzates from Agave tequilana as substrates for succinic acid production by Actinobacillus succinogenes in batch and repeated batch reactor.

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Corona-González, Rosa Isela; Varela-Almanza, Karla María; Arriola-Guevara, Enrique; Martínez-Gómez, Álvaro de Jesús; Pelayo-Ortiz, Carlos; Toriz, Guillermo

2016-04-01

The aim of this work was to obtain fermentable sugars by enzymatic or acid hydrolyses of Agave tequilana Weber bagasse in order to produce succinic acid with Actinobacillus succinogenes. Hydrolyses were carried out with mineral acids (sulfuric and hydrochloric acids) or a commercial cellulolytic enzyme, and were optimized statistically by a response surface methodology, having as factors the concentration of acid/enzyme and time of hydrolysis. The concentration of sugars obtained at optimal conditions for each hydrolysis were 21.7, 22.4y 19.8g/L for H2SO4, HCl and the enzymatic preparation respectively. Concerning succinic acid production, the enzymatic hydrolyzates resulted in the highest yield (0.446g/g) and productivity (0.57g/Lh) using A. succinogenes in a batch reactor system. Repeated batch fermentation with immobilized A. succinogenes in agar and with the enzymatic hydrolyzates resulted in a maximum concentration of succinic acid of 33.6g/L from 87.2g/L monosaccharides after 5 cycles in 40h, obtaining a productivity of 1.32g/Lh. Copyright © 2016. Published by Elsevier Ltd.

IDENTIFICATION OF SERINE CARBAPENEMASE AND METALLOCARBAPENEMASE ENZYMES IN PSEUDOMONAS AERUGINOSA IN GEMS MEDICAL COLLEGE, RAGOLU, SRIKAKULAM

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Radhika

2016-06-01

Full Text Available Various carbapenems have been reported in Pseudomonas aeruginosa such as VIM, NDM & OXA-48, etc. In addition, carbapenemase producers are usually associated with many other non–β-lactam resistance determinants which give rise to multidrug and pan drug resistant isolates. Detection of these enzymes in infected patients and in carriers are the two main approaches for prevention of their spread. Potential carbapenemase producers are currently screened first by susceptibility testing, using breakpoint values for carbapenems. However, many carbapenemase producers do not confer obvious resistance levels to carbapenems. So there is need for Laboratories to search for carbapenemase producers. In such instance, phenotypic based test such as Modified Hodge Test (MHT is very much useful in confirming in vitro production of carbapenemase enzymes. But this test does not differentiate serine carbapenemase enzyme (i.e. Ambler class A & C from metallocarbapenemase (i.e. Ambler class B. To differentiate these two enzymes, MHT positive isolates can be subjected to Disc Synergy test. These two tests are highly sensitive and specific and adaptable to any laboratory in the world. Out of 100 ceftazidime resistant Pseudomonas aeruginosa, 75(75% were sensitive, 7(7% were intermediate sensitive and 18(18% were resistant to imipenem. When the 18 imipenem resistant strains were subjected to Modified Hodge test, 15 gave positive results. When the 15 MHT positive strains subjected to disc synergy test, 8 were positive and 7 were negative showing that 8 were producing metallocarbapenemases and 7 were producing serine carbapenemases. Out of 7 intermediately imipenem sensitive isolates, 2 were producing metallocarbapenemase and 3 were producing serine carbapenemase. Hence, total number of imipenem resistant Pseudomonas aeruginosa isolates were 23.

Carbapenem-Resistant Bacteria Recovered from Faeces of Dairy Cattle in the High Plains Region of the USA.

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Webb, Hattie E; Bugarel, Marie; den Bakker, Henk C; Nightingale, Kendra K; Granier, Sophie A; Scott, H Morgan; Loneragan, Guy H

2016-01-01

A study was conducted to recover carbapenem-resistant bacteria from the faeces of dairy cattle and identify the underlying genetic mechanisms associated with reduced phenotypic susceptibility to carbapenems. One hundred and fifty-nine faecal samples from dairy cattle were screened for carbapenem-resistant bacteria. Phenotypic screening was conducted on two media containing ertapenem. The isolates from the screening step were characterised via disk diffusion, Modified Hodge, and Carba NP assays. Carbapenem-resistant bacteria and carbapenemase-producing isolates were subjected to Gram staining and biochemical testing to include Gram-negative bacilli. Whole genome sequencing was performed on bacteria that exhibited either a carbapenemase-producing phenotype or were not susceptible to ertapenem and were presumptively Enterobacteriaceae. Of 323 isolates collected from the screening media, 28 were selected for WGS; 21 of which were based on a carbapenemase-producing phenotype and 7 were presumptively Enterobacteriaceae and not susceptible to ertapenem. Based on analysis of WGS data, isolates included: 3 Escherichia coli harbouring blaCMY-2 and truncated ompF genes; 8 Aeromonas harbouring blacphA-like genes; 1 Acinetobacter baumannii harbouring a novel blaOXA gene (blaOXA-497); and 6 Pseudomonas with conserved domains of various carbapenemase-producing genes. Carbapenem resistant bacteria appear to be rare in cattle. Nonetheless, carbapenem-resistant bacteria were detected across various genera and were found to harbour a variety of mechanisms conferring reduced susceptibility. The development and dissemination of carbapenem-resistant bacteria in livestock would have grave implications for therapeutic treatment options in human medicine; thus, continued monitoring of carbapenem susceptibility among enteric bacteria of livestock is warranted.

Heterogeneity of Carbapenem Resistance Mechanisms Among Gram-Negative Pathogens in Lebanon: Results of the First Cross-Sectional Countrywide Study.

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Hammoudi Halat, Dalal; Moubareck, Carole Ayoub; Sarkis, Dolla Karam

2017-09-01

Carbapenem-resistant Gram-negative pathogens have progressively disseminated to different countries worldwide, presenting a serious public health concern. The aims of this study were to determine the prevalence of carbapenem resistance in Gram-negative bacteria in Lebanon, to elucidate molecular mechanisms, and to identify genetic relatedness of incriminated strains. Carbapenem nonsusceptible Enterobacteriaceae, Acinetobacter baumannii, and Pseudomonas were collected from 11 Lebanese hospitals in 2012. Antimicrobial susceptibility was assessed with phenotypic tests, genes encoding carbapenemases were screened via PCR-sequencing, and genetic relatedness was examined by PGFE and ERIC-PCR. A total of 398 nonrepetitive carbapenem nonsusceptible isolates were studied, of which 44 were Enterobacteriaceae, 142 were A. baumannii, and 212 were Pseudomonas. Among Enterobacteriaceae, 70.4% carried bla OXA-48-like gene on IncL/M-type plasmids, while acquired AmpC cephalosporinases, extended-spectrum-β-lactamases, and efflux-pump were additional contributors to carbapenem resistance. Among A. baumannii, 90% produced OXA-23 and GES-11 and carried insertion sequence ISAba1 upstream and adjacent to bla OXA-23 and bla Acinetobacter -derived cephalosporinases . Among Pseudomonas, 16% harbored VIM-2, 4.2% IMP-2, and 1.4% IMP-1 metallo-β-lactamases. Fingerprint analysis indicated that the spread of OXA-48-like carbapenemases was mostly mediated by horizontal transfer, while OXA-23 and GES-11 diffusion in A. baumannii and VIM-2 diffusion in P. aeruginosa were primarily due to clonal dissemination. This study is the first nationwide investigation of carbapenem resistance in Lebanon, showing low level of resistance in Enterobacteriaceae, and higher levels in A. baumannii and Pseudomonas. With current changes in the region, continuous surveillance of carbapenem resistance is crucial.

[Carbapenem antibiotics in hospitalised paediatric patients. Adherence to a therapeutic protocol].

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Montesinos-Sanchis, Elena; Moraga-Llop, Fernando A; Soler-Palacín, Pere; Oliveras-Arenas, María; Larrosa Escartín, M Nieves; Martínez Gómez, Xavier; Figueras-Nadal, Concepción

2014-12-01

To describe the use of carbapenems in children hospitalised outside intensive care and onco-haematology units, and assess adherence to a therapeutic protocol. A retrospective observational study was conducted on the use of carbapenems between January 2009 and December 2010. The study included children with a community-acquired infectious disease or a health care-associated infectious disease, and who were admitted to paediatric areas of the Vall d'Hebron University Hospital (Barcelona, Spain), other than intensive care, neonatology and onco-haematology units. Clinical data were collected and antibiotic consumption data were provided by the Pharmacy Department. A total of 51 episodes fulfilled the inclusion criteria. Carbapenem as initial empirical treatment was indicated in 31.4%, and applied as rescue therapy in the remainder. The instructions of the protocol were adhered to in 70.6% of the empirical and 87.5% of the targeted prescriptions (77.6% overall). A better match was found for empirical carbapenem in patients with a previous admission or underlying condition. Factors such as diagnosis, age or antibiotic use prior to admission did not affect the empirical indication of carbapenem. The establishment of a treatment protocol with carbapenem indications in our centre since 2007 has yielded significantly better results on the appropriateness of the prescription than those obtained in other studies. Copyright © 2012 Elsevier España, S.L.U. y Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Phenotypic characterization and colistin susceptibilities of carbapenem-resistant of Pseudomonas aeruginosa and Acinetobacter spp.

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Mohanty, Srujana; Maurya, Vijeta; Gaind, Rajni; Deb, Monorama

2013-11-15

Pseudomonas aeruginosa and Acinetobcter spp. are important nosocomial pathogens and carbapenem resistance is an emerging threat. Therapeutic options for infections with these isolates include colistin. This study was conducted to determine the prevalence of carbapenem resistance in P. aeruginosa and Acinetobacter spp. bloodstream isolates, phenotypically characterize the resistance mechanisms and evaluate the in vitro activity of colistin. Consecutive 145 (95 P.aeruginosa and 50 Acinetobacter spp.) non-repeat isolates were included. Antibiotic susceptibility testing was performed per CLSI guidelines. MIC for carbapenems and colistin was performed using Etest. Isolates showing reduced susceptibility or resistance to the carbapenems were tested for metallo-β-lactamase (MBL) production using imipenem-EDTA combined disk and MBL Etest. Carbapenem resistance was observed in 40% P. aeruginosa and 66.0% Acinetobacter spp. Carbapenem-resistant (CA-R) isolates were significantly (p carbapenem-susceptible isolates. Approximately half of the CA-R strains were multidrug-resistant, and 3.1-5.5% were resistant to all antibiotics tested. MBL was found in 76.3% and 69.7% of the P. aeruginosa and Acinetobacter spp., respectively. Colistin resistance was observed in three (6.0%) Acinetobacter isolates and eight (8.4%) P. aeruginosa. MIC50 for carbapenems were two to four times higher for MBL-positive compared to MBL-negative isolates, but no difference was seen in MIC for colistin. Carbapenem resistance was observed to be mediated by MBL in a considerable number of isolates. Colistin is an alternative for infections caused by CA-R isolates; however, MIC testing should be performed whenever clinical use of colistin is considered.

In vitro activity of SecA inhibitors in combination with carbapenems against carbapenem-hydrolysing class D β-lactamase-producing Acinetobacter baumannii.

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Chiu, Chun-Hsiang; Liu, Yu-Han; Wang, Yung-Chih; Lee, Yi-Tzu; Kuo, Shu-Chen; Chen, Te-Li; Lin, Jung-Chung; Wang, Fu-Der

2016-12-01

According to our previous study, OXA-58 translocates to the periplasm via the Sec pathway in carbapenem-resistant Acinetobacter baumannii (CRAb). In the present study, carbapenem-hydrolysing class D β-lactamases (CHDLs) belonging to the OXA-23, OXA-40 and OXA-51 families were examined to determine whether they are also Sec-dependent. Additionally, the effects of SecA inhibitors combined with carbapenems against CHDL-producing CRAb were examined. Cell fractionation and western blot analyses were performed to detect periplasmic His-tagged CHDLs. A chequerboard analysis with pairwise combinations of carbapenems (imipenem or meropenem) and SecA inhibitors (rose bengal, sodium azide or erythrosin B) was performed using six clinical CRAb isolates harbouring different CHDL genes. The fractional inhibitory concentration (FIC) index was determined. The combination with the lowest FIC index was subjected to a time-kill analysis to examine synergistic effects. In an in silico analysis, the CHDLs OXA-23, OXA-40 and OXA-51 were preferentially translocated via the Sec system. The SecA inhibitor rose bengal decreased periplasmic translocation of His-tagged OXA-23 and OXA-83 (belonging to the OXA-51 family), but not OXA-72 (belonging to the OXA-40 family) from ATCC 15151 transformants. Imipenem or meropenem with rose bengal showed synergistic effects (FIC index, ≤0.5) for six and four clinical isolates, respectively. Imipenem or meropenem with sodium azide showed no interactions (FIC index, 0.5-4) against all clinical isolates. Imipenem and rose bengal had the lowest FIC index and showed synergy at 24 h in the time-kill assay. Combinations of SecA inhibitors and carbapenems have synergistic effects against CHDL-producing CRAb. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Detection systems for carbapenemase gene identification should include the SME serine carbapenemase.

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Bush, Karen; Pannell, Megan; Lock, John L; Queenan, Anne Marie; Jorgensen, James H; Lee, Ryan M; Lewis, James S; Jarrett, Deidre

2013-01-01

Carbapenemase detection has become a major problem in hospitals that encounter outbreaks of infections caused by carbapenem-resistant Gram-negative bacteria. Rapid detection systems have been reported using multiplex PCR analyses and DNA microarray assays. Major carbapenemases that are detected by these systems include the KPC and OXA serine carbapenemases, and the IMP, VIM and NDM families of metallo-β-lactamases. However, increasing numbers of the SME serine carbapenemase are being reported from Serratia marcescens, especially from North and South America. These organisms differ from many of the other carbapenemase-producing pathogens in that they are generally susceptible to the expanded-spectrum cephalosporins ceftazidime and cefepime while retaining resistance to almost all other β-lactam antibiotics. Thus, multiplex PCR assays or DNA microarray testing of carbapenem-resistant S. marcescens isolates should include analyses for production of the SME carbapenemase. Confirmation of the presence of this enzyme may provide reassurance that oxyimino-cephalosporins can be considered for treatment of infections caused by these carbapenem-resistant pathogens. Copyright © 2012 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Measurement of Enzyme Kinetics by Use of a Blood Glucometer: Hydrolysis of Sucrose and Lactose

Science.gov (United States)

Heinzerling, Peter; Schrader, Frank; Schanze, Sascha

2012-01-01

An alternative analytical method for measuring the kinetic parameters of the enzymes invertase and lactase is described. Invertase hydrolyzes sucrose to glucose and fructose and lactase hydrolyzes lactose to glucose and galactose. In most enzyme kinetics studies, photometric methods or test strips are used to quantify the derivates of the…

Function and application of a non-ester-hydrolyzing carboxylesterase discovered in tulip.

Science.gov (United States)

Nomura, Taiji

2017-01-01

Plants have evolved secondary metabolite biosynthetic pathways of immense rich diversity. The genes encoding enzymes for secondary metabolite biosynthesis have evolved through gene duplication followed by neofunctionalization, thereby generating functional diversity. Emerging evidence demonstrates that some of those enzymes catalyze reactions entirely different from those usually catalyzed by other members of the same family; e.g. transacylation catalyzed by an enzyme similar to a hydrolytic enzyme. Tuliposide-converting enzyme (TCE), which we recently discovered from tulip, catalyzes the conversion of major defensive secondary metabolites, tuliposides, to antimicrobial tulipalins. The TCEs belong to the carboxylesterase family in the α/β-hydrolase fold superfamily, and specifically catalyze intramolecular transesterification, but not hydrolysis. This non-ester-hydrolyzing carboxylesterase is an example of an enzyme showing catalytic properties that are unpredictable from its primary structure. This review describes the biochemical and physiological aspects of tulipalin biogenesis, and the diverse functions of plant carboxylesterases in the α/β-hydrolase fold superfamily.

Molecular characterization of KPC-producing Klebsiella pneumoniae isolated from patients in a Public Hospital in Caracas, Venezuela.

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Falco Restrepo, Aura Dayana; Velásquez Nieves, Mariel Alexandra; Takiff, Howard

Klebsiella pneumoniae carbapenemase (KPC)-producing bacteria are amongst the most important causative agents of nosocomial infections worldwide. Isolates of this bacterium have been identified in Venezuela but little is known about their local spread. The aim of this study was to perform the molecular characterization of KPC-producing strains isolated from 2012 to 2013 in a public hospital in Caracas, Venezuela. Twenty-two K. pneumoniae clinical isolates phenotypically classified as KPC producing were subjected to PCR screening for the presence of bla KPC genes and their location within transposon Tn4401. The bla KPC PCR product was sequenced to identify the KPC alleles. Genotypic analysis was performed by means of repetitive extragenic palindromic PCR (rep-PCR) and Multi Locus Sequence Typing (MLST). Finally, conjugation and electroporation assays were used to determine whether the bla KPC genes were found in plasmids. All isolates contained the bla KPC-2 variant, and 21 of the 22 were associated with the Tn4401b isoform. The strains were distributed in 8 sequence types (ST), three of which were new. Conjugation and electroporation assays indicated that 95.5% (n=21/22) of the isolates contained the bla KPC gene in plasmids. This study on circulating bacterial strains and the identification of KPC alleles may help to understand the routes of dissemination and control their spread within this hospital. Copyright © 2017 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Sublethal Concentrations of Carbapenems Alter Cell Morphology and Genomic Expression of Klebsiella pneumoniae Biofilms

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Van Laar, Tricia A.; Chen, Tsute; You, Tao

2015-01-01

Klebsiella pneumoniae, a Gram-negative bacterium, is normally associated with pneumonia in patients with weakened immune systems. However, it is also a prevalent nosocomial infectious agent that can be found in infected surgical sites and combat wounds. Many of these clinical strains display multidrug resistance. We have worked with a clinical strain of K. pneumoniae that was initially isolated from a wound of an injured soldier. This strain demonstrated resistance to many commonly used antibiotics but sensitivity to carbapenems. This isolate was capable of forming biofilms in vitro, contributing to its increased antibiotic resistance and impaired clearance. We were interested in determining how sublethal concentrations of carbapenem treatment specifically affect K. pneumoniae biofilms both in morphology and in genomic expression. Scanning electron microscopy showed striking morphological differences between untreated and treated biofilms, including rounding, blebbing, and dimpling of treated cells. Comparative transcriptome analysis using RNA sequencing (RNA-Seq) technology identified a large number of open reading frames (ORFs) differentially regulated in response to carbapenem treatment at 2 and 24 h. ORFs upregulated with carbapenem treatment included genes involved in resistance, as well as those coding for antiporters and autoinducers. ORFs downregulated included those coding for metal transporters, membrane biosynthesis proteins, and motility proteins. Quantitative real-time PCR validated the general trend of some of these differentially regulated ORFs. Treatment of K. pneumoniae biofilms with sublethal concentrations of carbapenems induced a wide range of phenotypic and gene expression changes. This study reveals some of the mechanisms underlying how sublethal amounts of carbapenems could affect the overall fitness and pathogenic potential of K. pneumoniae biofilm cells. PMID:25583711

ST37 Klebsiella pneumoniae: development of carbapenem resistance in vivo during antimicrobial therapy in neonates.

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Li, Pengling; Wang, Min; Li, Xianping; Hu, Feihu; Yang, Min; Xie, Yixin; Cao, Wei; Xia, Xiaomeng; Zheng, Rong; Tian, Jingjing; Zhang, Kan; Chen, Fang; Tang, Aiguo

2017-08-01

To investigate the mechanism leading to in vivo carbapenem resistance development in Klebsiella pneumoniae. Carbapenemase was detected using the modified carbapenem inactivation method. β-lactamases resistant genes were identified by PCR and sequencing. Clonal relatedness was evaluated by random amplified polymorphic DNA and multiple locus sequence typing. The relationship between sequence typing and resistant genes was analyzed by using the chi-squared test. All ST37 carbapenem-resistant isolates were bla OXA-1 positive and all ST37 carbapenem-sensitive isolates were bla OXA-1 negative at Stage I. A significant relationship between carbapenem resistance and bla OXA-1 was observed. The bla OXA-1 -positive rate was significantly higher in ST37 K. pneumoniae than others. This is the first study about the development of carbapenem resistance in vivo potentially mediated by bla OXA-1 in ST37 K. pneumoniae among neonates.

Association between hypoalbuminemia and mortality among subjects treated with ertapenem versus other carbapenems: prospective cohort study.

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Zusman, O; Farbman, L; Tredler, Z; Daitch, V; Lador, A; Leibovici, L; Paul, M

2015-01-01

The aim of this study was to determine whether ertapenem, being highly protein bound, is less effective than other carbapenems in the presence of hypoalbuminemia. In a prospective cohort study, we included adults with clinically and microbiologically documented infections caused by carbapenem-susceptible Enterobacteriaceae who were hospitalized in a tertiary medical center from March 2010 to September 2012. We tested whether hypoalbuminemia (serum albumin carbapenem drug and the interaction between albumin and the carbapenem. Of 279 individual subjects included, 173 were treated with ertapenem and 106 with I/M. The odds ratio (OR) for 30-day mortality with hypoalbuminemia was 4.6 (95% confidence interval (CI) 2.1-10.1) among subjects with ertapenem versus 1.2 (95% CI 0.5-2.70) with I/M (p = 0.02 for difference between groups). In the regression model, the interaction between carbapenem type and albumin levels was significant (p = 0.03); for ertapenem lower albumin levels were associated with increased 30-day mortality (OR 2.45, 95% CI 1.19-5.05), while for I/M the change was not significant (OR 0.67, 95% CI 0.31-1.41). The model suggests that the risk of death for ertapenem-treated subjects quintupled when albumin was 2 g/dL compared to 4 g/dL. Hypoalbuminemia was associated with mortality significantly more among subjects treated with ertapenem compared to subjects treated with I/M. The effectiveness of current dosing schemes of ertapenem in subjects with significant hypoalbuminemia should be revisited. Copyright © 2014 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Risk factors for the acquisition of carbapenem-resistant Escherichia coli at a tertiary care center in South Korea: a matched case-control study.

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Ahn, Jin Young; Song, Je Eun; Kim, Min Hyung; Choi, Heun; Kim, Jae Kyung; Ann, Hea Won; Kim, Jung Ho; Jeon, Yongduk; Jeong, Su Jin; Kim, Sun Bean; Ku, Nam Su; Han, Sang Hoon; Song, Young Goo; Yong, Dongeun; Lee, Kyungwon; Kim, June Myung; Choi, Jun Yong

2014-06-01

Carbapenem resistance among gram-negative bacilli is an emerging threat worldwide. The objective of this study was to identify risk factors for the acquisition of carbapenem-resistant Escherichia coli (CRE). We conducted a matched case-control study comprising 57 cases of acquisition of CRE and 114 controls (1:2 matched) selected from patients with a culture of carbapenem-susceptible E coli between January 2006 and December 2010 at a 2000-bed tertiary care center in South Korea. On univariate analysis, previous use of carbapenem (P carbapenem (odds ratio [OR], 4.56; 95% confidence interval [CI] 1.44-14.46; P = .01) and previous use of fluoroquinolone (OR, 2.81; 95% CI, 1.14-6.99; P = .03) were independent risk factors. At this institute, the antibiotic selective pressure of carbapenems and fluoroquinolones was shown to be an important risk factor for the acquisition of CRE. Copyright © 2014 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

Expanding the Repertoire of Carbapenem-Hydrolyzing Metallo-ß-Lactamases by Functional Metagenomic Analysis of Soil Microbiota

DEFF Research Database (Denmark)

Gudeta, Dereje D.; Bortolaia, Valeria; Pollini, Simona

2016-01-01

, diversity and functionality of carbapenemase-encoding genes in soil microbiota by functional metagenomics. Ten plasmid libraries were generated by cloning metagenomic DNA from agricultural (n = 6) and grassland (n = 4) soil into Escherichia coli. The libraries were cultured on amoxicillin-containing agar......% identity). RAIphy analysis indicated that six enzymes (CRD3-1, GRD23-1, DHT2-1, SPN79-1, ALG6-1, and ALG11-1) originated from Proteobacteria, two (PEDO-1 and ESP-2) from Bacteroidetes and one (GRD33-1) from Gemmatimonadetes. All MBLs detected in soil microbiota were functional when expressed in E. coli...... approaches targeted different subpopulations in soil microbiota....

Bacterial Enzymes and Antibiotic Resistance- Oral Presentation

Energy Technology Data Exchange (ETDEWEB)

Maltz, Lauren [SLAC National Accelerator Lab., Menlo Park, CA (United States)

2015-08-25

By using protein crystallography and X-ray diffraction, structures of bacterial enzymes were solved to gain a better understanding of how enzymatic modification acts as an antibacterial resistance mechanism. Aminoglycoside phosphotransferases (APHs) are one of three aminoglycoside modifying enzymes that confer resistance to the aminoglycoside antibiotics via enzymatic modification, rendering many drugs obsolete. Specifically, the APH(2”) family vary in their substrate specificities and also in their preference for the phosphate donor (ADP versus GDP). By solving the structures of members of the APH(2”) family of enzymes, we can see how domain movements are important to their substrate specificity. Our structure of the ternary complex of APH(2”)-IIIa with GDP and kanamycin, when compared to the known structures of APH(2”)-IVa, reveals that there are real physical differences between these two enzymes, a structural finding that explains why the two enzymes differ in their preferences for certain aminoglycosides. Another important group of bacterial resistance enzymes are the Class D β-lactamases. Oxacillinase carbapenemases (OXAs) are part of this enzyme class and have begun to confer resistance to ‘last resort’ drugs, most notably carbapenems. Our structure of OXA-143 shows that the conformational flexibility of a conserved hydrophobic residue in the active site (Val130) serves to control the entry of a transient water molecule responsible for a key step in the enzyme’s mechanism. Our results provide insight into the structural mechanisms of these two different enzymes.

Risk factors for hospital-acquired bacteremia due to carbapenem-resistant Pseudomonas aeruginosa in a Colombian hospital.

Science.gov (United States)

Valderrama, Sandra Liliana; González, Pedro Felipe; Caro, María Alejandra; Ardila, Natalia; Ariza, Beatriz; Gil, Fabián; Álvarez, Carlos

2016-02-23

Bacteremia due to Pseudomonas aeruginosa resistant to carbapenems is a public health problem due to the limitations it places on therapeutic options, as well as the increased time patients must spend in hospital, costs and the risk of mortality.  To evaluate the risk factors for presentation of bacteremia due to carbapenem-resistant P. aeruginosa acquired in the Hospital Universitario San Ignacio between January 2008 and June 2014.  This was a case control study in which the case patients presented bacteremia due to P. aeruginosa resistant to carbapenems and the control group included patients with P. aeruginosa susceptible to this group of antibiotics. Variables such as the previous use of meropenem and ertapenem, immunosuppression and neoplasia were measured. Mortality and duration of hospital were also described.  In all, 168 patients were evaluated, of which 42 were cases and 126 controls. Using a multivariate model, the risk factors related to bacteremia due to carbapenem-resistant P. aeruginosa acquired in hospital were the following: use of parenteral nutrition (OR=8.28; 95% CI: 2.56-26.79; p=0); use of meropenem (OR=1.15; 95% CI: 1.03-1.28; p=0.01); and use of ciprofloxacin (OR=81.99; 95% CI: 1.14-5884; p=0.043).  In order to prevent the emergence of carbapenem-resistant P. aeruginosa, antimicrobial control programs should be strengthened by promoting the prudent administration of carbapenems and quinolones. The correct use of parenteral nutrition should also be monitored.

EVALUATION OF SUGARCANE BAGASSE ACID HYDROLYZATE TREATMENTS FOR XYLITOL PRODUCTION

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P.V. GURGEL

1998-09-01

Full Text Available Acid sugarcane bagasse hydrolyzate was submitted to pH shifts in order to remove toxic compounds from the medium. The hydrolyzate was treated with bases containing mono-, di- or tri-valent cations and H2SO4, and its performance as a fermentation medium was evaluated by the production of xylitol by Candida guilliermondii FTI 20037. The use of bases containing mono-valent cations was not an efficient method of detoxification, and the use of a tri-valent cation did not show any detectable improvement in detoxification. The treated hydrolyzate recovery (in volume is greatly affected by the utilized base. Treatment using Al(OH3 and NaOH showed the best hydrolyzate recovery (87.5%, while the others presented a recovery of about 45% of the original hydrolyzate volume. Considering the whole process, best results were achieved by treatment using Al(OH3 and NaOH which allowed 0.55 g of xylitol produced from each gram of xylose in the raw hydrolyzate.

Partially hydrolyzed guar gum as a potential prebiotic source.

Science.gov (United States)

Mudgil, Deepak; Barak, Sheweta; Patel, Ami; Shah, Nihir

2018-06-01

Guar galactomannan was enzymatically hydrolyzed to obtain partially hydrolyzed guar gum which can be utilized as prebiotic source. In present study, growth of probiotics (Lactic Acid Bacteria strains) were studied with glucose, partially hydrolyzed guar gum and native guar gum. All the six strains were galactose &/or mannose positive using the API CHl 50 test. Almost all these strains showed an ability to assimilate partially hydrolyzed guar gum with respect to increase in optical density and viable cell count with concomitant decrease in the pH of the growth medium. Streptococcus thermophilus MD2 exhibited higher growth (7.78 log cfu/ml) while P. parvulus AI1 showed comparatively less growth (7.24 log cfu/ml) as compared to used lactobacillus and Weissella strains. Outcomes of the current study suggest that partially hydrolyzed guar can be considered as potential prebiotic compound that may further stimulate the growth of potentially probiotic bacteria or native gut microflora. Copyright © 2018 Elsevier B.V. All rights reserved.

Angiotensin I-converting enzyme inhibitor derived from cottonseed ...

African Journals Online (AJOL)

Six proteolytic enzymes, including alcalase, flavourzyme, trypsin, neutrase, papain and pepsin, were employed to hydrolyze cottonseed protein to produce the hydrolysates of Angiotensin I-converting enzyme (ACE) inhibitory activity. The result indicated that the cottonseed protein hydrolysate (CPH) produced by papain had ...

Impact of antibiotic exposure on occurrence of nosocomial carbapenem-resistant Acinetobacter baumannii infection: a case control study.

Science.gov (United States)

Chusri, Sarunyou; Silpapojakul, Kachornsakdi; McNeil, Edward; Singkhamanan, Kamonnut; Chongsuvivatwong, Virasakdi

2015-02-01

Carbapenem-resistant Acinetobacter baumannii (CRAB) infection is one of the most important healthcare associated diseases worldwide. Although antibiotic use is recognized as a risk factor for CRAB infection, the impact of antibiotic class and length of use on CRAB infection is still unclear. A case-control study was conducted in adult intensive care units and general wards of Songklanagarind Hospital, a tertiary-care hospital in southern Thailand, to investigate the effect of different antibiotic exposure and the duration of use on the risk of developing CRAB infection. Cases were defined as patients with carbapenem-susceptible A. baumannii (CSAB) or CRAB infection. Controls were randomly selected from patients and matched 1:1 with cases using ward and date of admission. Multinomial logistic regression was used to compute relative risk ratios (RRR) and 95% confidence intervals (CI) for CRAB infection. Of 197 cases with A. baumannii infection, there were 139 with CRAB infection and 58 with CSAB infection. Compared to the control group, use of fluoroquinolones, broad-spectrum cephalosporins and carbapenems for more than three days increased the risk of CRAB infection with RRR (95% CI) of 81.2 (38.1-862.7), 31.3 (9.9-98.7) and 112.1 (7.1-1770.6), respectively. The RRR (95% CI) for one to three day treatment of fluoroquinolones, broad-spectrum cephalosporins and carbapenems were 5.4 (0.8-38.7), 6.2 (0.1-353.2) and 63.3 (15.6-256.9), respectively. Long-term use of certain antibiotics and even short term use of carbapenems increased the risk of CRAB infection. In this setting, use of these antibiotics, especially carbapenems, should be limited to reduce CRAB infection. Copyright © 2014. Published by Elsevier Ltd.

A retrospective study of risk factors for carbapenem-resistant Klebsiella pneumoniae acquisition among ICU patients.

Science.gov (United States)

Hu, Yangmin; Ping, Yanting; Li, Leiqing; Xu, Huimin; Yan, Xiaofeng; Dai, Haibin

2016-03-31

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is rapidly emerging as a life-threatening nosocomial infection. In this study, we aim to identify risk factors, especially antibiotic use, for CRKP infection among intensive care unit (ICU) patients. This was a matched case-control study of a 67-bed ICU in a tertiary care teaching hospital from 1 January 2011 through 30 June 2013. The control cases were selected among the patients with carbapenem-susceptible Klebsiella pneumoniae (CSKP) and were matched with CRKP cases for year of ICU admission and site of infection. The clinical outcomes and antibiotic treatments were analyzed. One hundred and thirty patients were included in the study (65 cases and 65 controls). Bivariable analysis showed that age of patients (p = 0.044), number of antibiotic groups (p = 0.001), and exposure to carbapenems (p carbapenems, previous carbapenem exposure (p carbapenems is an independent risk factor for CRKP infection. Patients with this clinical factor should be targeted for interventions to reduce the subsequent risk of infection.

Prolonged delay for controlling KPC-2-producing Klebsiella pneumoniae outbreak: the role of clinical management.

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Delory, T; Seringe, E; Antoniotti, G; Novakova, I; Goulenok, C; Paysant, I; Boyer, S; Carbonne, A; Naas, T; Astagneau, P

2015-10-01

Carbapenemase-producing Enterobacteriaceae (CPE) are becoming of immediate concern for infection control policies. Prompt detection of CPE on health care setting admission is crucial to halt the spread of an outbreak. We report a cluster of 13 Klebsiella pneumoniae carbapenemase (KPC)-2-producing K pneumoniae cases in a tertiary care hospital.The objective of this study was to identify contributing factors originating the outbreak. An outbreak investigation was conducted using descriptive epidemiology, observation of health care practices, and interviews of management staff. A root cause analysis was performed to identify patent and latent failures of infection control measures using the association of litigation and risk management method. The main patent failure was the delay in identifying KPC-2-producing K pneumoniae carriers. Contributing factors were work and environmental factors: understaffing, lack of predefined protocols, staff members' characteristics, and underlying patients' characteristics. Latent failures were as follows: no promotion of the national guidelines for prevention of CPE transmission, no clear procedure for the management of patients hospitalized abroad, no clear initiative for promoting a culture of quality in the hospital, biologic activity recently outsourced to a private laboratory, and poor communication among hospital members. Clinical management should be better promoted to control hospital outbreaks and should include team work and safety culture. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

UTILITY OF FUNCTIONALIZED AGAROSE NANOPARTICLES IN HYDROLYZING LACTOSE IN BATCH REACTORS FOR DAIRY INDUSTRIES

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Shakeel Ahmed Ansari

Full Text Available The present study investigates the synthesis of agarose nanoparticles (ANPs and its surface modification by galactose for the immobilization of β-galactosidase. Galactose modified ANPs retained 91% enzyme activity upon immobilization. Optimum pH (4.5 and temperature (50 ºC remains unchanged after immobilization. However, immobilized enzyme retained greater catalytic activity against lower and higher, pH and temperature ranges. Immobilized β-galactosidase retained 89% biocatalytic activity even at 4% galactose concentration as compared to enzyme in solution, and exhibited 81% activity even after seventh repeated uses. Immobilized enzyme hydrolyzed greater amount of lactose at higher temperatures as compared to β-galactosidase in solution, thereby suggesting its potential application in obtaining lactose-free dairy products at large scale.

Acinetobacter baumannii clonal lineages I and II harboring different carbapenem-hydrolyzing-β-lactamase genes are widespread among hospitalized burn patients in Tehran.

Science.gov (United States)

Mahdian, Somayeh; Sadeghifard, Nourkhoda; Pakzad, Iraj; Ghanbari, Fatemeh; Soroush, Setareh; Azimi, Lila; Rastegar-Lari, Abdolaziz; Giannouli, Maria; Taherikalani, Morovat

2015-01-01

The aim of this study was to analyze antimicrobial resistance patterns and their encoding genes and genotypic diversity of Acinetobacter baumannii isolated from burn patients in Tehran, Iran. The presence of extended-spectrum beta-lactamase- and blaOXA-encoding genes among 37 multidrug resistant (MDR) A. baumannii strains isolated from patients hospitalized in a teaching hospital in Tehran was evaluated. Susceptibility to 7 antibiotics was tested by disk agar diffusion and to polymyxin B and colistin was tested by E-test, according to CLSI guidelines. All isolates were then analyzed by PCR for the presence of blaIMP, blaVIM, blaSIMblaOXA-23, blaOXA-24, and blaOXA-58-like carbapenemase genes, and blaOXA-51-like, blaTEM, blaSHV, blaPER, blaVEB, and blaGIM genes. Genotyping of A. baumannii strains was performed by repetitive sequence-based (REP)-PCR and cluster analysis of REP-PCR profiles. A. baumannii isolates were assigned to international clones by multiplex PCR sequence group analysis. Twenty-five A. baumannii isolates were classified as MDR, and 12 were classified as extensively drug resistant. All isolates were susceptible to colistin and polymyxin B. Eighty-one percent of the isolates was resistant to imipenem or meropenem and harbored at least one or both of the blaOXA-23-like or blaOXA-24-like carbapenemase genes. Co-existence of different resistance genes was found among carbapenem-resistant isolates. Multiplex PCR sequence group analysis most commonly assigned A. baumannii isolates to international clones I (18/37; 48.6%) and II (18/37; 48.6%). An alarming increase in resistance to carbapenems and the spread of blaOXA-23-like and/or blaOXA-24-like carbapenemase genes was observed among A. baumannii strains belonging to clonal lineages I and II, isolated from burn patients in Tehran. Copyright © 2015 King Saud Bin Abdulaziz University for Health Sciences. Published by Elsevier Ltd. All rights reserved.

Clonality and Resistome analysis of KPC-producing Klebsiella pneumoniae strain isolated in Korea using whole genome sequencing.

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Lee, Yangsoon; Kim, Bong-Soo; Chun, Jongsik; Yong, Ji Hyun; Lee, Yeong Seon; Yoo, Jung Sik; Yong, Dongeun; Hong, Seong Geun; D'Souza, Roshan; Thomson, Kenneth S; Lee, Kyungwon; Chong, Yunsop

2014-01-01

We analyzed the whole genome sequence and resistome of the outbreak Klebsiella pneumoniae strain MP14 and compared it with those of K. pneumoniae carbapenemase- (KPC-) producing isolates that showed high similarity in the NCBI genome database. A KPC-2-producing multidrug-resistant (MDR) K. pneumoniae clinical isolate was obtained from a patient admitted to a Korean hospital in 2011. The strain MP14 was resistant to all tested β-lactams including monobactam, amikacin, levofloxacin, and cotrimoxazole, but susceptible to tigecycline and colistin. Resistome analysis showed the presence of β-lactamase genes including bla KPC-2, bla SHV-11, bla TEM-169, and bla OXA-9. MP14 also possessed aac(6'-)Ib, aadA2, and aph(3'-)Ia as aminoglycoside resistance-encoding genes, mph(A) for macrolides, oqxA and oqxB for quinolone, catA1 for phenicol, sul1 for sulfonamide, and dfrA12 for trimethoprim. Both SNP tree and cgMLST analysis showed the close relatedness with the KPC producers (KPNIH strains) isolated from an outbreak in the USA and colistin-resistant strains isolated in Italy. The plasmid-scaffold genes in plasmids pKpQil, pKpQil-IT, pKPN3, or pKPN-IT were identified in MP14, KPNIH, and Italian strains. The KPC-2-producing MDR K. pneumoniae ST258 stain isolated in Korea was highly clonally related with MDR K. pneumoniae strains from the USA and Italy. Global spread of KPC-producing K. pneumoniae is a worrying phenomenon.

Clonality and Resistome Analysis of KPC-Producing Klebsiella pneumoniae Strain Isolated in Korea Using Whole Genome Sequencing

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Yangsoon Lee

2014-01-01

Full Text Available We analyzed the whole genome sequence and resistome of the outbreak Klebsiella pneumoniae strain MP14 and compared it with those of K. pneumoniae carbapenemase- (KPC- producing isolates that showed high similarity in the NCBI genome database. A KPC-2-producing multidrug-resistant (MDR K. pneumoniae clinical isolate was obtained from a patient admitted to a Korean hospital in 2011. The strain MP14 was resistant to all tested β-lactams including monobactam, amikacin, levofloxacin, and cotrimoxazole, but susceptible to tigecycline and colistin. Resistome analysis showed the presence of β-lactamase genes including blaKPC-2, blaSHV-11, blaTEM-169, and blaOXA-9. MP14 also possessed aac(6′-Ib, aadA2, and aph(3′-Ia as aminoglycoside resistance-encoding genes, mph(A for macrolides, oqxA and oqxB for quinolone, catA1 for phenicol, sul1 for sulfonamide, and dfrA12 for trimethoprim. Both SNP tree and cgMLST analysis showed the close relatedness with the KPC producers (KPNIH strains isolated from an outbreak in the USA and colistin-resistant strains isolated in Italy. The plasmid-scaffold genes in plasmids pKpQil, pKpQil-IT, pKPN3, or pKPN-IT were identified in MP14, KPNIH, and Italian strains. The KPC-2-producing MDR K. pneumoniae ST258 stain isolated in Korea was highly clonally related with MDR K. pneumoniae strains from the USA and Italy. Global spread of KPC-producing K. pneumoniae is a worrying phenomenon.

Spatial molecular epidemiology of carbapenem-resistant and New Delhi metallo beta-lactamase (blaNDM)-producing Escherichia coli in the piglets of organized farms in India.

Science.gov (United States)

Pruthvishree, B S; Vinodh Kumar, O R; Sinha, D K; Malik, Y P S; Dubal, Z B; Desingu, P A; Shivakumar, M; Krishnaswamy, N; Singh, B R

2017-06-01

A cross-sectional study was conducted in 10 government-organized pig farms between 2014 and 2016 representing seven states of India to understand the epidemiology of carbapenem resistance in the Escherichia coli. In this study, fecal sample (n = 673) from non-diarrheic (n = 501) and diarrheic (n = 172) piglets were processed for isolation of carbapenem resistant E. coli. Of 673, E. coli isolate (n = 112) was genotyped for confirming the carbapenem resistance and associated virulence factors. Of the 112 isolates, 23 were phenotypically resistant to carbapenem and 8 were carrying the New Delhi metallo beta-lactamase (blaNDM) gene. The carbapenem-resistant isolates also produced extended spectrum beta-lactamases and were multidrug resistant. The PCR-based pathotyping revealed the presence of stx1, stx2, eae and hlyA genes. The enterobacterial repetitive intergenic consensus PCR dendrogram analysis of the isolates yielded three distinct clusters. The statistical analysis revealed no association between carriages of carbapenem-resistant E. coli in different breed of piglets however, location, sex, health status of piglets and age showed significant difference. The spatial analysis with SaTScan helped in identification of carbapenem-resistant clusters. The presence of carbapenem resistant E. coli isolates with virulence genes in the piglet poses a potential public health risk through possible access and spread via the food chain and environment. Efflux pump may also play an important role in carbapenem resistance in piglet E. coli isolates. Furthermore, identification of risk factors in relation to spatial clusters will help in designing preventive strategies for reducing the risk of spread of carbapenem resistant bacteria. 1. Piglets harbor carbapenem resistant E. coli and have great public health significance. 2. Apart from carbapenemase, efflux pump is also important for carbapenem resistance. 3. This is the first report of blaNDM in the piglets from India. © 2017

The influence of carbapenem resistance on mortality in solid organ transplant recipients with Acinetobacter baumannii infection

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de Gouvêa Erika

2012-12-01

Full Text Available Abstract Background Infection with carbapenem-resistant Acinetobacter baumannii has been associated with high morbidity and mortality in solid organ transplant recipients. The main objective of this study was to assess the influence of carbapenem resistance and other potential risk factors on the outcome of A. baumannii infection after kidney and liver transplantation. Methods Retrospective study of a case series of A. baumannii infection among liver and renal transplant recipients. The primary outcome was death associated with A. baumannii infection. Multivariate logistic regression was used to assess the influence of carbapenem resistance and other covariates on the outcome. Results Forty-nine cases of A. baumannii infection affecting 24 kidney and 25 liver transplant recipients were studied. Eighteen cases (37% were caused by carbapenem-resistant isolates. There were 17 (35% deaths associated with A. baumannii infection. In unadjusted analysis, liver transplantation (p = 0.003, acquisition in intensive care unit (p = 0.001, extra-urinary site of infection (p A. baumannii infection. The number of deaths associated with A. baumannii infection was higher among patients infected with carbapenem-resistant isolates, but the difference was not significant (p = 0.28. In multivariate analysis, the risk of A. baumannii-associated mortality was higher in patients with infection acquired in the intensive care unit (odds ratio [OR] = 34.8, p = 0.01 and on mechanical ventilation (OR = 15.2, p = 0.04. Appropriate empiric antimicrobial therapy was associated with significantly lower mortality (OR = 0.04, p = 0.03, but carbapenem resistance had no impact on it (OR = 0.73, p = 0.70. Conclusion These findings suggest that A. baumannii-associated mortality among liver and kidney transplant recipients is influenced by baseline clinical severity and by the early start of appropriate therapy, but not by carbapenem

Antibiotic trapping by plasmid-encoded cmy-2-lactamase combined with reduced outer membrane permeability as a mechanism of carbapenem resistance in escherichia coli

NARCIS (Netherlands)

W.H.F. Goessens (Wil); A.K. van der Bij (Akke); R. van Boxtel (Ria); J.D.D. Pitout (J. D D); P. van Ulsen (Peter); D.C. Melles (Damian); J. Tommassen (Jan)

2013-01-01

textabstractA liver transplant patient was admitted with cholangitis, for which meropenem therapy was started. Initial cultures showed a carbapenem-susceptible (CS) Escherichia coli strain, but during admission, a carbapenem-resistant (CR) E. coli strain was isolated. Analysis of the outer membrane

Detection of KPC-2 in a Clinical Isolate of Proteus mirabilis and First Reported Description of Carbapenemase Resistance Caused by a KPC Beta-Lactamase in P. mirabilis

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An isolate of Proteus mirabilis recovered from bacterial cultures was shown to be resistant to imipenem, meropenem, and ertapenem by disk diffusion susceptibility testing. Amplification of whole cell and/or plasmid DNA recovered from the isolate using primers specific for the blaKPC carbapenemase g...

Associated factors and outcomes for OXA-232 Carbapenem-resistant Enterobacteriaceae infections in a tertiary care centre in Mexico City: A case-control-control study.

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Torres-González, Pedro; Ortiz-Brizuela, Edgar; Cervera-Hernandez, Miguel Enrique; Bobadilla-Del Valle, Miriam; Martínez-Gamboa, Areli; Sifuentes-Osornio, José; Ponce-de-Leon, Alfredo

2016-10-01

We describe the outcomes and factors associated with OXA-232 producing carbapenem-resistant Enterobacteriaceae infections. A case-control-control study was performed; each case of infection by a carbapenem-resistant/OXA-232 (OXA-232-cases, n=27) was matched by isolation site, species, and date, with 2 cases of infection by carbapenem-susceptible/third-generation cephalosporin-susceptible (TGCS-controls, n=54) and 2 cases by carbapenem-susceptible/ESBL producing Enterobacteriaceae (ESBL-controls, n=54); 66% were urinary tract and 18.5% intra-abdominal infections. In the multivariable analysis with ESBL-controls, previous use β-lactam/β-lactamase antibiotics (OR 6.2; 95% CI 1.6-23.8) and, third-generation cephalosporins (OR 0.2; 95% CI 0.05-0.8) were associated with OXA-232 infection; with TGSC-controls previous use of β-lactam/β-lactamase antibiotics (OR 3.7; 95% 1.1-12.0) was associated. Among the OXA-232-cases, 29% received imipenem/cilastatin or meropenem, 11.1% ceftriaxone, 22.2% a carbapenem-based combination and 33.3% other antimicrobials as treatment. Previous β-lactam/β-lactamase antibiotics are associated with OXA-232 infections, and some may be treated with other active carbapenems or, in the absence of ESBL, third-generation cephalosporins. Copyright © 2016 Elsevier Inc. All rights reserved.

Acquisition of carbapenem resistance by plasmid-encoded-AmpC-expressing Escherichia coli

NARCIS (Netherlands)

Tommassen - van Boxtel, Ria; Wattel, Agnes A.; Arenas Busto, Jesus; Goessens, Wil H.F.; Tommassen, J

2017-01-01

Although AmpC β-lactamases can barely degrade carbapenems, if at all, they can sequester them and prevent them from reaching their targets. Thus, carbapenem resistance in Escherichia coli and other Enterobacteriaceae can result from AmpC production and simultaneous reduction of antibiotic influx

Biological effects of hydrolyzed quinoa extract from seeds of Chenopodium quinoa Willd.

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Meneguetti, Quele Adriana; Brenzan, Mislaine Adriana; Batista, Marcia Regina; Bazotte, Roberto Barbosa; Silva, Daniel Rodrigues; Garcia Cortez, Diógenes Aparício

2011-06-01

An extract from seeds of Chenopodium quinoa Willd. (quinoa), termed hydrolyzed quinoa (HQ), was obtained by enzymatic hydrolysis from seeds of the quinoa variety BRS-Piabiru. Analysis of the physical and chemical properties of quinoa and HQ showed that the hydrolyzed extract is rich in essential amino acids, particularly those with branched chains (leucine, isoleucine, and valine). In addition, we evaluated the biological effects of HQ, particularly the toxicological potential. For this purpose, male Wistar rats were assigned randomly to four groups: (1) sedentary supplemented group, which received HQ (2,000 mg/kg); (2) sedentary control group, non-supplemented; (3) exercised supplemented group (i.e., rats subjected to aerobic physical exercise that received HQ [2,000 mg/kg]); and (4) exercised control group (i.e., rats subjected to aerobic physical exercise, non-supplemented). After 30 days, all groups were analyzed for levels of serum glucose, cholesterol, triacylglycerol, total protein, albumin, uric acid, and urea and activities of the enzymes alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase. Body weight gain, dietary intake, and lipid deposition were also analyzed. The results showed no hepatic and renal toxicity of HQ. Moreover, decreased food intake, body weight, fat deposition, and blood triacylglycerol level were observed in the supplemented groups (sedentary and exercised supplemented groups). These results suggest a potential use of HQ in human nutrition.

Clinical review: Balancing the therapeutic, safety, and economic issues underlying effective antipseudomonal carbapenem use

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Slama, Thomas G

2008-01-01

Antipseudomonal carbapenems have played a useful role in our antimicrobial armamentarium for 20 years. However, a review of their use during that period creates concern that their clinical effectiveness is critically dependent on attainment of an appropriate dosing range. Unfortunately, adequate carbapenem dosing is missed for many reasons, including benefit/risk misconceptions, a narrow therapeutic window for imipenem and meropenem (due to an increased rate of seizures at higher doses), increasingly resistant pathogens requiring higher doses than are typically given, and cost containment issues that may limit their use. To improve the use of carbapenems, several initiatives should be considered: increase awareness about appropriate treatment with carbapenems across hospital departments; determine optimal dosing regimens for settings where multidrug resistant organisms are more likely encountered; use of, or combination with, an alternative antimicrobial agent having more favorable pharmacokinetic, pharmacodynamic, or adverse event profile; and administer a newer carbapenem with lower propensity for resistance development (for example, reduced expression of efflux pumps or greater stability against carbapenemases). PMID:18983709

Molecular epidemiology of carbapenem non-susceptible Acinetobacter nosocomialis in a medical center in Taiwan.

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Yang, Ya-Sung; Lee, Yi-Tzu; Wang, Yung-Chih; Chiu, Chun-Hsiang; Kuo, Shu-Chen; Sun, Jun-Ren; Yin, Ti; Chen, Te-Li; Lin, Jung-Chung; Fung, Chang-Phone; Chang, Feng-Yee

2015-04-01

The mechanism by which carbapenem non-susceptible Acinetobacter nosocomialis (CNSAN) is disseminated is rarely described in the literature. In this study, we delineated the molecular epidemiology of CNSAN isolated from patients in a medical center in Taiwan. Fifty-four non-duplicate bloodstream isolates of CNSAN were collected at the Taipei Veterans General Hospital between 2001 and 2007. Pulsed-field gel electrophoresis (PFGE) was performed to determine their clonal relationship. Carbapenem-resistance genes and associated genetic structures were detected by polymerase chain reaction (PCR) mapping. Southern hybridization was performed to determine the plasmid location of carbapenem-resistance genes. Transmissibility of these genes to Acinetobacterbaumannii was demonstrated by conjugation tests. The overall carbapenem non-susceptibility rate among A. nosocomialis isolates during the study period was 21.6% (54/250). PFGE revealed three major pulsotypes: H (n=23), I (n=10), and K (n=8). The most common carbapenem-resistance gene was blaOXA-58 (43/54, 79.6%), containing an upstream insertion sequence IS1006 and a truncated ISAba3 (IS1006-ΔISAba3-like-blaOXA-58). All isolates belonging to the pulsotypes H, I, and K carried plasmid located IS1006-ΔISAba3-like-blaOXA-58. A common plasmid carrying ISAba1-blaOXA-82 was found in six isolates, which belonged to five pulsotypes. A type 1 integron that carried blaIMP-1 was detected in different plasmids of seven isolates, which belonged to five pulsotypes. Plasmids carrying these carbapenem-resistant determinants were transmissible from A. nosocomialis to A. baumannii via conjugation. In this medical center, CNSAN mainly emerged through clonal dissemination; propagation of plasmids and integrons carrying carbapenem-resistant determinants played a minor role. This study showed that plasmids carrying carbapenem-resistant determinants are transmissible from A. nosocomialis to A. baumannii. Copyright © 2015 Elsevier B.V. All

Fermentation of corn-cob hydrolyzates with butanol bacteria

Energy Technology Data Exchange (ETDEWEB)

Nakhmanovich, B M; Senkevich, V V; Scheblykina, N A; Lipshits, V V

1960-01-01

Experiments to produce BuOH from hydrolyzates of corn cobs and sunflower husks after addition to beet molasses are described. Corn cobs were heated at atmosphere pressure at 100/sup 0/ for 3 to 8 hourse at 4.1% initial H/sub 2/SO/sub 4/ concentration, for sunflower hulls 120/sup 0/ for 20 minutes was used. The concentration,of solids was 25 and 33%, respectively. The hydrolyzate was neutralized with lime to pH 6.7 to 6.9 and (NH/sub 4/)/sub 2/DO/sub 4/ and superphosphate were added. The best yields were obtained if the mash contained 40 to 60% hydrolyzate and 60 to 40% molasses (on sugar basis). The sugar content of the mashes was 3.7%. Yields in total organic solvents and BuOH were 40% and 27%, respectively, calculated on the initial sugar in the mash. Fermentation time was 2 to 3 days. The strain used in probably a variety of Clostridium butylicum.

Risk factors and outcomes of carbapenem-resistant Klebsiella pneumoniae infections

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Eleonora Pistella

2016-12-01

Full Text Available In the nosocomial setting, antimicrobial-resistant Enterobacteriaceae are a growing challenge, and alarming trends in resistance are currently reported all over the world. Isolates of Enterobacteriaceae producing ampC β-lactamases and extended spectrum β-lactamases are endemic in many hospitals, and are frequently resistant also to other classes of antibiotics, such as fluoroquinolones and aminoglycosides. The risk of infections due to multi-drug resistant strains should be considered also for outpatients who have had recent contact with the health system. Both nosocomial and health-care associated infections should be treated with a combination of antibiotics active against multi-drug resistant Gram negative and methicillin-resistant Staphylococcus aureus. In the absence of effective antimicrobial stewardship programs, this aggressive therapeutic approach might lead to abuse of broad-spectrum antibiotics, with consequent increase in resistances. To contain the possible antibiotic overuse, several decisional strategies, often based on risk-score systems supporting the clinical decisions, have been proposed. In this context of high antibiotic selection pressure, carbapenem-resistant pathogens recently began to spread in many hospitals. Carbapenem-resistant Klebsiella pneumoniae, as well as carbapenem-resistant Acinetobacter baumannii and P. aeruginosa, represent the new major challenges to patient safety. Against these organisms the initial empiric treatment is generally ineffective. The poor clinical outcome associated with carbapenem- resistant K. pneumoniae infections is probably due to the delete in the beginning of an appropriate antibiotic treatment, rather than to the increased virulence of pathogens. Only few therapeutic options are available, including colistin, tigecycline, aminoglycosides and carbapenems in selected cases. Several combinations of these antibiotics have been used, but no ideal regimen has been currently established.

Enzymatic hydrolysis (pepsin assisted by ultrasound in the functional Properties of hydrolyzates from different collagens

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Alessandra Roseline Vidal

2018-03-01

Full Text Available ABSTRACT: Enzymatic hydrolysis (pepsin assisted with or without ultrasound in the functional properties of hydrolyzates from different collagens were analyzed. Degree of hydrolysis, antioxidant activity (DPPH and antimicrobial activity (MIC were assessed. The treatment that resulted in greater antioxidant activity for the fiber sample was with the use of 4% of enzyme and concomitant ultrasound (40.7%, leading to a degree of hydrolysis of 21.7%. For the powdered fiber sample the hydrolysis treatment with use of 4% of enzyme resulted in lower protein content (6.97mg/mL, higher degree of hydrolysis (19.9% and greater antioxidant activity (38.6%. The hydrolyzates showed inhibitory capacity against gram-negative bacteria Salmonella choleraesuis and gram-positive bacteria Staphylococcus aureus. It can be concluded that enzymatic hydrolysis concomitant or not with the use of ultrasound increased the functionality of the fiber and powdered fiber samples, for the other samples its use as supplementary treatment was not productive, due to the worse results of antioxidant activity (DPPH reported. However, it provided greater hydrolysis degree.

Antibiotic Trapping by Plasmid-Encoded CMY-2 beta-Lactamase Combined with Reduced Outer Membrane Permeability as a Mechanism of Carbapenem Resistance in Escherichia coli

NARCIS (Netherlands)

Goessens, W.H.F.; van der Bij, A.K.; van Boxtel, R.; Pitout, J.D.D.; van Ulsen, J.P.; Melles, D.C.; Tommassen, J.

2013-01-01

A liver transplant patient was admitted with cholangitis, for which meropenem therapy was started. Initial cultures showed a carbapenem-susceptible (CS) Escherichia coli strain, but during admission, a carbapenem-resistant (CR) E. coli strain was isolated. Analysis of the outer membrane protein

Impact of Combination Antimicrobial Therapy on Mortality Risk for Critically Ill Patients with Carbapenem-Resistant Bacteremia

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Bauer, Seth R.; Neuner, Elizabeth A.; Lam, Simon W.

2015-01-01

There are limited treatment options for carbapenem-resistant Gram-negative infections. Currently, there are suggestions in the literature that combination therapy should be used, which frequently includes antibiotics to which the causative pathogen demonstrates in vitro resistance. This case-control study evaluated risk factors associated with all-cause mortality rates for critically ill patients with carbapenem-resistant Gram-negative bacteremia. Adult patients who were admitted to an intensive care unit with sepsis and a blood culture positive for Gram-negative bacteria resistant to a carbapenem were included. Patients with polymicrobial, recurrent, or breakthrough infections were excluded. Included patients were classified as survivors (controls) or nonsurvivors (cases) at 30 days after the positive blood culture. Of 302 patients screened, 168 patients were included, of whom 90 patients died (53.6% [cases]) and 78 survived (46.4% [controls]) at 30 days. More survivors received appropriate antibiotics (antibiotics with in vitro activity) than did nonsurvivors (93.6% versus 53.3%; P carbapenems) (87.2% versus 80%; P = 0.21). After adjustment for baseline factors with multivariable logistic regression, combination therapy was independently associated with decreased risk of death (odds ratio, 0.19 [95% confidence interval, 0.06 to 0.56]; P carbapenem-resistant Gram-negative bacteremia. However, that association is lost if in vitro activity is not considered. PMID:25845872

Incidence of carbapenem-resistant gram negatives in Italian transplant recipients: a nationwide surveillance study.

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Lanini, Simone; Costa, Alessandro Nanni; Puro, Vincenzo; Procaccio, Francesco; Grossi, Paolo Antonio; Vespasiano, Francesca; Ricci, Andrea; Vesconi, Sergio; Ison, Michael G; Carmeli, Yehuda; Ippolito, Giuseppe

2015-01-01

Bacterial infections remain a challenge to solid organ transplantation. Due to the alarming spread of carbapenem-resistant gram negative bacteria, these organisms have been frequently recognized as cause of severe infections in solid organ transplant recipients. Between 15 May and 30 September 2012 we enrolled 887 solid organ transplant recipients in Italy with the aim to describe the epidemiology of gram negative bacteria spreading, to explore potential risk factors and to assess the effect of early isolation of gram negative bacteria on recipients' mortality during the first 90 days after transplantation. During the study period 185 clinical isolates of gram negative bacteria were reported, for an incidence of 2.39 per 1000 recipient-days. Positive cultures for gram negative bacteria occurred early after transplantation (median time 26 days; incidence rate 4.33, 1.67 and 1.14 per 1,000 recipient-days in the first, second and third month after SOT, respectively). Forty-nine of these clinical isolates were due to carbapenem-resistant gram negative bacteria (26.5%; incidence 0.63 per 1000 recipient-days). Carbapenems resistance was particularly frequent among Klebsiella spp. isolates (49.1%). Recipients with longer hospital stay and those who received either heart or lung graft were at the highest risk of testing positive for any gram negative bacteria. Moreover recipients with longer hospital stay, lung recipients and those admitted to hospital for more than 48h before transplantation had the highest probability to have culture(s) positive for carbapenem-resistant gram negative bacteria. Forty-four organ recipients died (0.57 per 1000 recipient-days) during the study period. Recipients with at least one positive culture for carbapenem-resistant gram negative bacteria had a 10.23-fold higher mortality rate than those who did not. The isolation of gram-negative bacteria is most frequent among recipient with hospital stays >48 hours prior to transplant and in those

Incidence of carbapenem-resistant gram negatives in Italian transplant recipients: a nationwide surveillance study.

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Simone Lanini

Full Text Available Bacterial infections remain a challenge to solid organ transplantation. Due to the alarming spread of carbapenem-resistant gram negative bacteria, these organisms have been frequently recognized as cause of severe infections in solid organ transplant recipients.Between 15 May and 30 September 2012 we enrolled 887 solid organ transplant recipients in Italy with the aim to describe the epidemiology of gram negative bacteria spreading, to explore potential risk factors and to assess the effect of early isolation of gram negative bacteria on recipients' mortality during the first 90 days after transplantation. During the study period 185 clinical isolates of gram negative bacteria were reported, for an incidence of 2.39 per 1000 recipient-days. Positive cultures for gram negative bacteria occurred early after transplantation (median time 26 days; incidence rate 4.33, 1.67 and 1.14 per 1,000 recipient-days in the first, second and third month after SOT, respectively. Forty-nine of these clinical isolates were due to carbapenem-resistant gram negative bacteria (26.5%; incidence 0.63 per 1000 recipient-days. Carbapenems resistance was particularly frequent among Klebsiella spp. isolates (49.1%. Recipients with longer hospital stay and those who received either heart or lung graft were at the highest risk of testing positive for any gram negative bacteria. Moreover recipients with longer hospital stay, lung recipients and those admitted to hospital for more than 48h before transplantation had the highest probability to have culture(s positive for carbapenem-resistant gram negative bacteria. Forty-four organ recipients died (0.57 per 1000 recipient-days during the study period. Recipients with at least one positive culture for carbapenem-resistant gram negative bacteria had a 10.23-fold higher mortality rate than those who did not.The isolation of gram-negative bacteria is most frequent among recipient with hospital stays >48 hours prior to transplant

Treatment Options for Carbapenem-Resistant and Extensively Drug-Resistant Acinetobacter baumannii Infections

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Viehman, J. Alexander; Nguyen, Minh-Hong; Doi, Yohei

2014-01-01

Acinetobacter baumannii is a leading cause of healthcare-associated infections worldwide. Due to various intrinsic and acquired mechanisms of resistance, most β-lactam agents are not effective against many strains, and carbapenems have played an important role in therapy. Recent trends show many infections are caused by carbapenem-resistant, or even extensively drug-resistant (XDR) strains, for which effective therapy is not well established. Evidence to date suggests that colistin constitutes the backbone of therapy, but the unique pharmacokinetic properties of colistin have led many to suggest the use of combination antimicrobial therapy. However, the combination of agents and dosing regimens that delivers the best clinical efficacy while minimizing toxicity is yet to be defined. Carbapenems, sulbactam, rifampin and tigecycline have been the most studied in the context of combination therapy. Most data regarding therapy for invasive, resistant A. baumannii infections come from uncontrolled case series and retrospective analyses, though some clinical trials have been completed and others are underway. Early institution of appropriate antimicrobial therapy is shown to consistently improve survival of patients with carbapenem-resistant and XDR A. baumannii infection, but the choice of empiric therapy in these infections remains an open question. This review summarizes the most current knowledge regarding the epidemiology, mechanisms of resistance, and treatment considerations of carbapenem-resistant and XDR A. baumannii. PMID:25091170

The purpose and appropriateness of carbapenem use in a single university hospital, 2009-2013.

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Yoon, Doran; Koo, Hei Lim; Choe, Pyeong Gyun; Song, Kyoung-Ho; Park, Wan Beom; Bang, Ji Hwan; Kim, Eu Suk; Park, Sang Won; Kim, Hong Bin; Oh, Myoung-Don; Kim, Nam Joong

2016-06-01

This is a retrospective review study to investigate changes in carbapenem consumption and to evaluate the proportion of inappropriate empirical use of carbapenem in the months of September and October of 2009, 2011, and 2013 in a single university-affiliated hospital. Total carbapenem use was classified into 3 categories: prophylactic, directed, and empirical. If an empirical prescription was continued without documentation of any eligible etiologic microorganism, we defined this as 'inappropriate' use. We also considered it 'inappropriate' when a patient's culture revealed no pathogen and the patient was initially not in severe sepsis or septic shock and did not have a history of admission to a health-care facility or of colonization with a pathogen eligible for carbapenem within 3 months. The total amount was 48.1, 51.1, and 91.0 defined daily doses/1000 patient-days in 2009, 2011, and 2013, respectively. Empirical use accounted for 78.4% of all prescriptions. The proportion of inappropriate empirical use ranged from 15.0 to 38.9% of the empirical carbapenem prescriptions.

Production, Purification, and Gene Cloning of a β-Fructofuranosidase with a High Inulin-hydrolyzing Activity Produced by a Novel Yeast Aureobasidium sp. P6 Isolated from a Mangrove Ecosystem.

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Jiang, Hong; Ma, Yan; Chi, Zhe; Liu, Guang-Lei; Chi, Zhen-Ming

2016-08-01

After screening of over 300 yeast strains isolated from the mangrove ecosystems, it was found that Aureobasidium sp. P6 strain had the highest inulin-hydrolyzing activity. Under the optimal conditions, this yeast strain produced an inulin-hydrolyzing activity of 30.98 ± 0.8 U/ml after 108 h of a 10-l fermentation. After the purification, a molecular weight of the enzyme which had the inulin-hydrolyzing activity was estimated to be 47.6 kDa, and the purified enzyme could actively hydrolyze both sucrose and inulin and exhibit a transfructosylating activity at 30.0 % sucrose, converting sucrose into fructooligosaccharides (FOS), indicating that the purified enzyme was a β-D-fructofuranosidase. After the full length of a β-D-fructofuranosidase gene (accession number KU308553) was cloned from Aureobasidium sp. P6 strain, a protein deduced from the cloned gene contained the conserved sequences MNDPNGL, RDP, ECP, FS, and Q of a glycosidehydrolase GH32 family, respectively, but did not contain a conserved sequence SVEVF, and the amino acid sequence of the protein from Aureobasidium sp. P6 strain had a high similarity to that of the β-fructofuranosidase from any other fungal strains. After deletion of the β-D-fructofuranosidase gene, the disruptant still had low inulin hydrolyzing and invertase activities and a trace amount of the transfructosylating activity, indicating that the gene encoding an inulinase may exist in the Aureobasidium sp. P6 strain.

Sustained pediatric antimicrobial stewardship program with consultation to infectious diseases reduced carbapenem resistance and infection-related mortality.

Science.gov (United States)

Horikoshi, Yuho; Suwa, Junichi; Higuchi, Hiroshi; Kaneko, Tetsuji; Furuichi, Mihoko; Aizawa, Yuta; Fukuoka, Kahoru; Okazaki, Kaoru; Ito, Kenta; Shoji, Takayo

2017-11-01

The impact of pediatric antimicrobial stewardship programs (ASP) on antimicrobial resistance (AMR) remains largely unknown. This study aimed to evaluate the AMR for carbapenem of Gram-negative bacilli (GNB) and carbapenem use with infectious diseases consultation after the implementation of an ASP. This quasi-experimental study was conducted at Tokyo Metropolitan Children's Medical Center in Japan. The pre- and post-intervention periods were April 2010 to September 2011 and October 2011 to March 2017, respectively. The pre-intervention phase consisted of consultations with the infectious diseases service alone. The ASP was implemented during the post-intervention phase. The carbapenem resistance rates of GNB were calculated. The correlation between carbapenem resistance rates and carbapenem day of therapy (DOT) was examined. The outcome metrics were compared by average length of hospitalization, all-cause mortality, and infection-related mortality. A positive correlation was observed between the carbapenem resistance rate in Pseudomonas aeruginosa and DOT (0.76, p=0.04). The carbapenem resistance rate in P. aeruginosa (pcarbapenem use and resistance in P. aeruginosa, leading to favorable outcomes in terms of length of hospitalization and infection-related mortality. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Carbapenem MICs in Escherichia coli and Klebsiella Species Producing Extended-Spectrum β-Lactamases in Critical Care Patients from 2001 to 2009.

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Johnson, J Kristie; Robinson, Gwen L; Pineles, Lisa L; Ajao, Adebola O; Zhao, LiCheng; Albrecht, Jennifer S; Harris, Anthony D; Thom, Kerri A; Furuno, Jon P

2017-04-01

Extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae strains are increasing in prevalence worldwide. Carbapenem antibiotics are used as a first line of therapy against ESBL-producing Enterobacteriaceae We examined a cohort of critical care patients for gastrointestinal colonization with carbapenem-resistant ESBL-producing strains (CR-ESBL strains). We cultured samples from this cohort of patients for ESBL-producing Klebsiella spp. and Escherichia coli and then tested the first isolate from each patient for susceptibility to imipenem, doripenem, meropenem, and ertapenem. Multilocus sequence typing was performed on isolates that produced an ESBL and that were carbapenem resistant. Among all patients admitted to an intensive care unit (ICU), 4% were positive for an ESBL-producing isolate and 0.64% were positive for a CR-ESBL strain on surveillance culture. Among the first ESBL-producing E. coli and Klebsiella isolates from the patients' surveillance cultures, 11.2% were carbapenem resistant. Sequence type 14 (ST14), ST15, ST42, and ST258 were the dominant sequence types detected in this cohort of patients, with ST15 and ST258 steadily increasing in prevalence from 2006 to 2009. Patients colonized by a CR-ESBL strain were significantly more likely to receive antipseudomonal and anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) therapy prior to ICU admission than patients colonized by carbapenem-susceptible ESBL-producing strains. They were also significantly more likely to have received a cephalosporin or a carbapenem antibiotic than patients colonized by carbapenem-susceptible ESBL-producing strains. In conclusion, in a cohort of patients residing in intensive care units within the United States, we found that 10% of the isolates were resistant to at least one carbapenem antibiotic. The continued emergence of carbapenem-resistant ESBL-producing strains is of significant concern, as infections due to these organisms are notoriously difficult to

Factores relacionados con el control exitoso de un brote por Klebsiella pneumoniae productora de KPC-2 en una unidad de cuidado intensivo en Bogotá, Colombia

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Gisell Bustos-Moya

Full Text Available La resistencia a carbapenémicos en Klebsiella pneumoniae ha aumentado de manera considerable, incrementando las tasas de morbimortalidad. El objetivo de este trabajo fue describir las características epidemiológicas, microbiológicas y las medidas de intervención que permitieron el control exitoso de un brote de Klebsiella pneumoniae productora de KPC-2. Métodos: El estudio se realizó en 2 periodos: el primero durante el brote, con instauración de un protocolo de medidas de intervención; y el segundo, de seguimiento posbrote. Se realizaron pruebas de identificación y susceptibilidad por sistema automatizado, tamización de carbapenemasas por test de Hodge modificado, PCR para detección de los genes bla KPC , bla KPC-2 , NDM-1 y estudio de clonalidad por electroforesis de campos pulsados. Resultados: Durante el brote, se identificaron 18 aislamientos de Klebsiella pneumoniae productora de KPC en 11 pacientes. Tres casos fueron confirmados como infección intrahospitalaria. La técnica de PCR reveló la presencia del gen bla KPC en 21 de 22 aislamientos (pacientes y medio ambiente y se identificó la presencia de un clon con una similitud superior al 75%. En el periodo posbrote los cultivos ambientales y de búsqueda de colonizados fueron negativos. Discusión: Se evidenció un control exitoso del brote producido por un clon. La implementación de un protocolo de intervención y la monitorización de su cumplimiento, la comunicación efectiva y el trabajo en equipo fueron indispensables para evitar su propagación y evitar un comportamiento endémico posbrote.

Ceftazidime Is the Key Diversification and Selection Driver of VIM-Type Carbapenemases.

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Martínez-García, Laura; González-Alba, José M; Baquero, Fernando; Cantón, Rafael; Galán, Juan Carlos

2018-05-08

In recent decades, carbapenems have been considered the last line of antibiotic therapy for Gram-negative bacterial infections. Unfortunately, strains carrying a high diversity of β-lactamases able to hydrolyze carbapenems have emerged in the clinical setting. Among them, VIM β-lactamases have diversified in a bloom of variants. The evolutionary reconstructions performed in this work revealed that, at the end of the 1980s, two independent events involving diversification from VIM-2 and VIM-4 produced at least 25 VIM variants. Later, a third event involving diversification from VIM-1 occurred in the mid-1990s. In a second approach to understanding the emergence of VIM carbapenemases, 44 mutants derived from VIM-2 and VIM-4 were obtained by site-directed mutagenesis based on those positions predicted to be under positive selection. These variants were expressed in an isogenic context. The more-evolved variants yielded increased levels of hydrolytic efficiency toward ceftazidime to a higher degree than toward carbapenems. In fact, an antagonist effect was frequently observed. These results led us to develop an experimental-evolution step. When Escherichia coli strains carrying VIM-2 or VIM-4 were submitted to serial passages at increasing concentrations of carbapenems or ceftazidime, more-efficient new variants (such as VIM-11 and VIM-1, with N165S [bearing a change from N to S at position 165] and R228S mutations, respectively) were only obtained when ceftazidime was present. Therefore, the observed effect of ceftazidime in the diversification and selection of VIM variants might help to explain the recent bloom of carbapenemase diversity, and it also represents another example of the potential universal effect exerted by ceftazidime in the selection of more-efficient β-lactamase variants, as in TEM, CTX-M, or KPC enzymes. IMPORTANCE One of the objectives recently proposed by the World Health Organization (WHO) Assembly in the global plan on antimicrobial

Carbapenem use in French hospitals: A nationwide survey at the patient level.

Science.gov (United States)

Gauzit, Rémy; Pean, Yves; Alfandari, Serge; Bru, Jean-Pierre; Bedos, Jean-Pierre; Rabaud, Christian; Robert, Jérôme

2015-12-01

The objective of this study was to evaluate the characteristics of carbapenem use in French healthcare settings in order to guide future actions. Healthcare facilities voluntarily participated in a nationwide cross-sectional survey in 2011. Medical data and reasons for carbapenem treatment (CPR) and discontinuation were recorded for all patients treated with carbapenems. A total of 2338 patients were recorded by 207 facilities. The median duration of CPR was 8 days, and 31.4% of patients received CPR for >10 days. An antibiotic consultant was involved in the initial choice of CPR in 36.8% of cases. CPR was chosen on an empirical (EP) basis for 1229 patients (52.6%), mainly because of severe sepsis (48.6%) or a perceived risk of bacterial resistance (33.7%). Among EP patients, de-escalation was more frequent in the case of intervention of an antibiotic consultant (35.1%) than without intervention (22.9%) (Pcarbapenems or to fluoroquinolones. Among the latter, de-escalation was performed in 59 cases (14.9%). The intervention of an antibiotic consultant did not favour de-escalation in this group. In conclusion, carbapenems are frequently used for treating suspected or confirmed multidrug-resistant bacteria, and overall CPR duration is long. De-escalation is frequently not implemented despite isolates being susceptible to other drugs. More frequent antibiotic consultant intervention may help to decrease carbapenem use in the case of EP treatment. Copyright © 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Recycle bioreactor for bioethanol production from wheat starch. 1. Cold enzyme hydrolysis

Energy Technology Data Exchange (ETDEWEB)

Lang, X.; Hill, G.A.; MacDonald, D.G. [Department of Chemical Engineering, Saskatchewan (Canada)

2001-06-01

A 5 L membrane bioreactor system has been designed and operated at low temperature to hydrolyze starch granules directly to sugars using barley {alpha}-amylase. The system includes a temperature and pH controlled, well-mixed bioreactor; microfilters to separate and recycle granules; and ultrafilters to separate and recycle enzyme molecules. Operation in batch mode demonstrated similar kinetics and low productivity observed earlier in shake flasks, whereas continuous flow operation was not successful due to enzyme inhibition and degradation. Sequential batch mode operation, involving filtration after each batch hydrolysis, produced optimum productivity measured at 0.16 grams of starch granules hydrolyzed per gram of enzyme per hour for more than 100 hours of operation. (author)

Research Applications of Proteolytic Enzymes in Molecular Biology

OpenAIRE

Mótyán, János András; Tóth, Ferenc; Tőzsér, József

2013-01-01

Proteolytic enzymes (also termed peptidases, proteases and proteinases) are capable of hydrolyzing peptide bonds in proteins. They can be found in all living organisms, from viruses to animals and humans. Proteolytic enzymes have great medical and pharmaceutical importance due to their key role in biological processes and in the life-cycle of many pathogens. Proteases are extensively applied enzymes in several sectors of industry and biotechnology, furthermore, numerous research applications ...

Carbapenem-resistance and pathogenicity of bovine Acinetobacter indicus-like isolates.

Directory of Open Access Journals (Sweden)

Peter Klotz

Full Text Available The objective of this study was to characterize blaOXA-23 harbouring Acinetobacter indicus-like strains from cattle including genomic and phylogenetic analyses, antimicrobial susceptibility testing and evaluation of pathogenicity in vitro and in vivo. Nasal and rectal swabs (n = 45 from cattle in Germany were screened for carbapenem-non-susceptible Acinetobacter spp. Thereby, two carbapenem resistant Acinetobacter spp. from the nasal cavities of two calves could be isolated. MALDI-TOF mass spectrometry and 16S rDNA sequencing identified these isolates as A. indicus-like. A phylogenetic tree based on partial rpoB sequences indicated closest relation of the two bovine isolates to the A. indicus type strain A648T and human clinical A. indicus isolates, while whole genome comparison revealed considerable intraspecies diversity. High mimimum inhibitory concentrations were observed for carbapenems and other antibiotics including fluoroquinolones and gentamicin. Whole genome sequencing and PCR mapping revealed that both isolates harboured blaOXA-23 localized on the chromosome and surrounded by interrupted Tn2008 transposon structures. Since the pathogenic potential of A. indicus is unknown, pathogenicity was assessed employing the Galleria (G. mellonella infection model and an in vitro cytotoxicity assay using A549 human lung epithelial cells. Pathogenicity in vivo (G. mellonella killing assay and in vitro (cytotoxicity assay of the two A. indicus-like isolates was lower compared to A. baumannii ATCC 17978 and similar to A. lwoffii ATCC 15309. The reduced pathogenicity of A. indicus compared to A. baumannii correlated with the absence of important virulence genes encoding like phospholipase C1+C2, acinetobactin outer membrane protein BauA, RND-type efflux system proteins AdeRS and AdeAB or the trimeric autotransporter adhesin Ata. The emergence of carbapenem-resistant A. indicus-like strains from cattle carrying blaOXA-23 on transposable elements and

Molecular Epidemiology of Carbapenem Non-Susceptible Acinetobacter baumannii in France

Science.gov (United States)

Jeannot, Katy; Diancourt, Laure; Vaux, Sophie; Thouverez, Michelle; Ribeiro, Amandina; Coignard, Bruno; Courvalin, Patrice; Brisse, Sylvain

2014-01-01

Carbapenem-resistant Acinetobacter baumannii have emerged globally. The objective of this study was to investigate the epidemiology, clonal diversity and resistance mechanisms of imipenem non-susceptible A. baumannii isolates in France. Between December 2010 and August 2011, 132 notifications were collected, including 37 outbreaks corresponding to 242 cases (2 to 55 per cluster). Multilocus sequence typing, pulsed-field gel electrophoresis (PFGE) and characterisation of carbapenemase-encoding genes were performed on 110 non-repetitive isolates. Gene bla OXA-23 was the most frequently detected (82%), followed by bla OXA-24 (11%) and bla OXA-58 (7%). Eleven sequence types (ST) were distinguished, among which sequence types ST1, ST2 (64%), ST20, ST25, ST85 and ST107. Isolates from epidemiological clusters had the same ST and resistance genes, indicating probable transmission within centres. In contrast, PFGE types of isolates differed among centres, arguing against transmission among centers. This study provides the first epidemiological snapshot of the population of A. baumannii with reduced susceptibility to carbapenems from France, and further underlines the predominance of international clones. PMID:25517732

Enzyme recycling in lignocellulosic biorefineries

DEFF Research Database (Denmark)

Jørgensen, Henning; Pinelo, Manuel

2017-01-01

platform. Cellulases are the most important enzymes required in this process, but the complex nature of lignocellulose requires several other enzymes (hemicellulases and auxiliary enzymes) for efficient hydrolysis. Enzyme recycling increases the catalytic productivity of the enzymes by reusing them...... for several batches of hydrolysis, and thereby reduces the overall cost associated with the hydrolysis. Research on this subject has been ongoing for many years and several promising technologies and methods have been developed and demonstrated. But only in a very few cases have these technologies been...... upscaled and tested in industrial settings, mainly because of many difficulties with recycling of enzymes from the complex lignocellulose hydrolyzate at industrially relevant conditions, i.e., high solids loadings. The challenges are associated with the large number of different enzymes required...

NNDSS - Table II. Carbapenemase-producing carbapenem-resistant Enterobacteriaceae

Data.gov (United States)

U.S. Department of Health & Human Services — NNDSS - Table II. Carbapenemase-producing carbapenem-resistant Enterobacteriaceae - 2018. In this Table, provisional cases of selected notifiable diseases (≥1,000...

First identification of class A carbapenemase-producing Klebsiella pneumoniae in the Republic of Ireland.

LENUS (Irish Health Repository)

Roche, C

2009-04-02

The Klebsiella pneumoniae carbapenemase (KPC) was detected in a carbapenem-resistant respiratory isolate of Klebsiella pneumoniae in an Irish hospital. This is the first report of a KPC-producing isolate in the Republic of Ireland. The isolate was resistant to all beta-lactams. Furthermore, it had reduced susceptibility to three other classes of non-beta-lactam antibiotics. The isolate was not associated with travel abroad. Detection of KPC-producing bacteria has important infection control and public health implications.

Higher third-generation cephalosporin prescription proportion is associated with lower probability of reducing carbapenem use: a nationwide retrospective study

Directory of Open Access Journals (Sweden)

Allison Muller

2018-01-01

Full Text Available Abstract Background The ongoing extended spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE pandemic has led to an increasing carbapenem use, requiring release of guidelines for carbapenem usage in France in late 2010. We sought to determine factors associated with changes in carbapenem use in intensive care units (ICUs, medical and surgical wards between 2009 and 2013. Methods This ward-level multicentre retrospective study was based on data from French antibiotic and multidrug-resistant bacteria surveillance networks in healthcare facilities. Antibiotic use was expressed in defined daily doses per 1000 patient-days. Factors associated with the reduction in carbapenem use (yes/no over the study period were determined from random-effects logistic regression model (493 wards nested within 259 healthcare facilities: ward characteristics (type, size…, ward antibiotic use (initial antibiotic use [i.e., consumption of a given antibiotic in 2009], initial antibiotic prescribing profile [i.e., proportion of a given antibiotic in the overall antibiotic consumption in 2009] and reduction in the use of a given antibiotic between 2009 and 2013 and regional ESBL-PE incidence rate in acute care settings in 2011. Results Over the study period, carbapenem consumption in ICUs (n = 85, medical (n = 227 and surgical wards (n = 181 was equal to 73.4, 6.2 and 5.4 defined daily doses per 1000 patient-days, respectively. Release of guidelines was followed by a significant decrease in carbapenem use within ICUs and medical wards, and a slowdown in use within surgical wards. The following factors were independently associated with a higher probability of reducing carbapenem use: location in Eastern France, higher initial carbapenem prescribing profile and reductions in consumption of fluoroquinolones, glycopeptides and piperacillin/tazobactam. In parallel, factors independently associated with a lower probability of reducing carbapenem use were

Evolution of Metallo-β-lactamases: Trends Revealed by Natural Diversity and in vitro Evolution

Directory of Open Access Journals (Sweden)

María-Rocío Meini

2014-07-01

Full Text Available The production of β-lactamase enzymes is one of the most distributed resistance mechanisms towards β-lactam antibiotics. Metallo-β-lactamases constitute a worrisome group of these kinds of enzymes, since they present a broad spectrum profile, being able to hydrolyze not only penicillins, but also the latest generation of cephalosporins and carbapenems, which constitute at present the last resource antibiotics. The VIM, IMP, and NDM enzymes comprise the main groups of clinically relevant metallo-β-lactamases. Here we present an update of the features of the natural variants that have emerged and of the ones that have been engineered in the laboratory, in an effort to find sequence and structural determinants of substrate preferences. This knowledge is of upmost importance in novel drug design efforts. We also discuss the advances in knowledge achieved by means of in vitro directed evolution experiments, and the potential of this approach to predict natural evolution of metallo-β-lactamases.The production of β-lactamase enzymes is one of the most distributed resistance mechanisms towards β-lactam antibiotics. Metallo-β-lactamases constitute a worrisome group of these kinds of enzymes, since they present a broad spectrum profile, being able to hydrolyze not only penicillins, but also the latest generation of cephalosporins and carbapenems, which constitute at present the last resource antibiotics. The VIM, IMP, and NDM enzymes comprise the main groups of clinically relevant metallo-β-lactamases. Here we present an update of the features of the natural variants that have emerged and of the ones that have been engineered in the laboratory, in an effort to find sequence and structural determinants of substrate preferences. This knowledge is of upmost importance in novel drug design efforts. We also discuss the advances in knowledge achieved by means of in vitro directed evolution experiments, and the potential of this approach to predict

Purification and properties of amylolytic enzyme from Aspergillus oryzae MIBA316

OpenAIRE

仮屋, 麻紀子; 矢野, めぐむ; 瀧井, 幸男; Makiko, Kariya; Megumu, Yano; Yukio, Takii

2003-01-01

Amylolytic enzyme was purified to electrophoretically homogeneous state from culture broth of Aspergillus oryzae MIBA316. This enzyme hydrolyzed preferentially amylopectin, starch and glycogen. Approaches to complete breakdown of starch to its components and their utilization in food processing were discussed.

Novel Aminoglycoside Resistance Transposons and Transposon-Derived Circular Forms Detected in Carbapenem-Resistant Acinetobacter baumannii Clinical Isolates

Science.gov (United States)

Dwibedi, Chinmay Kumar; Sjöström, Karin; Edquist, Petra; Wai, Sun Nyunt; Uhlin, Bernt Eric

2016-01-01

Acinetobacter baumannii has emerged as an important opportunistic pathogen equipped with a growing number of antibiotic resistance genes. Our study investigated the molecular epidemiology and antibiotic resistance features of 28 consecutive carbapenem-resistant clinical isolates of A. baumannii collected throughout Sweden in 2012 and 2013. The isolates mainly belonged to clonal complexes (CCs) with an extensive international distribution, such as CC2 (n = 16) and CC25 (n = 7). Resistance to carbapenems was related to blaOXA-23 (20 isolates), blaOXA-24/40-like (6 isolates), blaOXA-467 (1 isolate), and ISAba1-blaOXA-69 (1 isolate). Ceftazidime resistance was associated with blaPER-7 in the CC25 isolates. Two classical point mutations were responsible for resistance to quinolones in all the isolates. Isolates with high levels of resistance to aminoglycosides carried the 16S rRNA methylase armA gene. The isolates also carried a variety of genes encoding aminoglycoside-modifying enzymes. Several novel structures involved in aminoglycoside resistance were identified, including Tn6279, ΔTn6279, Ab-ST3-aadB, and different assemblies of Tn6020 and TnaphA6. Importantly, a number of circular forms related to the IS26 or ISAba125 composite transposons were detected. The frequent occurrence of these circular forms in the populations of several isolates indicates a potential role of these circular forms in the dissemination of antibiotic resistance genes. PMID:26824943

Deaths Attributable to Carbapenem-Resistant Enterobacteriaceae Infections

Centers for Disease Control (CDC) Podcasts

2014-08-06

Dr. Mike Miller reads an abridged version of the article, Deaths Attributable to Carbapenem-Resistant Enterobacteriaceae Infections.  Created: 8/6/2014 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 8/13/2014.

National sentinel site surveillance for antimicrobial resistance in ...

African Journals Online (AJOL)

All isolates exhibiting reduced susceptibility to carbapenems were PCR tested for blaKPC and blaNDM-1 resistance genes. Results. Overall, 68.3% of the 2 774 isolates were ESBL-positive, showing resistance to cefotaxime, ceftazidime and cefepime. Furthermore, 46.5% of all isolates were resistant to ciprofloxacin and ...

Carbapenems versus alternative antibiotics for the treatment of bloodstream infections caused by Enterobacter, Citrobacter or Serratia species: a systematic review with meta-analysis.

Science.gov (United States)

Harris, Patrick N A; Wei, Jane Y; Shen, Andrew W; Abdile, Ahmed A; Paynter, Stuart; Huxley, Rachel R; Pandeya, Nirmala; Doi, Yohei; Huh, Kyungmin; O'Neal, Catherine S; Talbot, Thomas R; Paterson, David L

2016-02-01

This systematic review and meta-analysis compared effects of different antibiotics on mortality in patients with bloodstream infections caused by Enterobacteriaceae with chromosomal AmpC β-lactamase. Databases were systematically searched for studies reporting mortality in patients with bloodstream infections caused by AmpC producers treated with carbapenems, broad-spectrum β-lactam/β-lactamase inhibitors (BLBLIs), quinolones or cefepime. Pooled ORs for mortality were calculated for cases that received monotherapy with these agents versus carbapenems. PROSPERO international prospective register of systematic reviews (CRD42014014992; 18 November 2014). Eleven observational studies were included. Random-effects meta-analysis was performed on studies reporting empirical and definitive monotherapy. In unadjusted analyses, no significant difference in mortality was found between BLBLIs versus carbapenems used for definitive therapy (OR 0.87, 95% CI 0.32-2.36) or empirical therapy (OR 0.48; 95% CI 0.14-1.60) or cefepime versus carbapenems as definitive therapy (OR 0.61; 95% CI 0.27-1.38) or empirical therapy (0.60; 95% CI 0.17-2.20). Use of a fluoroquinolone as definitive therapy was associated with a lower risk of mortality compared with carbapenems (OR 0.39; 95% CI 0.19-0.78). Three studies with patient-level data were used to adjust for potential confounders. The non-significant trends favouring non-carbapenem options in these studies were diminished after adjustment for age, sex and illness severity scores, suggestive of residual confounding. Despite limitations of available data, there was no strong evidence to suggest that BLBLIs, quinolones or cefepime were inferior to carbapenems. The reduced risk of mortality observed with quinolone use may reflect less serious illness in patients, rather than superiority over carbapenems. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights

Probing the Outflowing Multiphase Gas ∼1 kpc below the Galactic Center

Energy Technology Data Exchange (ETDEWEB)

Savage, Blair D.; Kim, Tae-Sun; Wakker, Bart P. [Department of astronomy, University of Wisconsin, Madison, 475 North Charter Street, Madison, WI 53706 (United States); Fox, Andrew J. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD, 21218 (United States); Massa, Derck [Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301 (United States); Bordoloi, Rongmon [MIT-Kavli Center for Astrophysics and Space Research, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Jenkins, Edward B. [Princeton University Observatory, Princeton, NJ 08544 (United States); Lehner, Nicolas [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Bland-Hawthorn, Joss [Institute of Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia); Lockman, Felix J. [Green Bank Observatory, P.O. Box 2, Green Bank, WV 24944 (United States); Hernandez, Svea [Department of Astrophysics, Radboud University, Nijmegen, PO Box 9010, 6500 GL Nijmegen (Netherlands)

2017-10-01

Comparison of interstellar medium (ISM) absorption in the UV spectrum of LS 4825, a B1 Ib−II star d  = 21 ± 5 kpc from the Sun toward l  = 1.°67 and b  = −6.°63, with ISM absorption toward an aligned foreground star at d  < 7.0 ± 1.7 kpc, allows us to isolate and study gas associated with the Milky Way nuclear wind. Spectra from the Space Telescope Imaging Spectrograph show low-ionization absorption out to d  < 7 kpc (e.g., O i, C ii, Mg ii, Si ii, Fe ii, S ii) only between 0 and 40 km s{sup −1}, while absorption at d  > 7 kpc, ∼1 kpc below the Galactic plane, is complex and spans −290 to +94 km s{sup −1}. The intermediate and high ions Si iii, C iv, Si iv, and N v show extremely strong absorption with multiple components from −283 to 107 km s{sup −1}, implying that the ISM ∼1 kpc below the Galactic center has a substantial reservoir of plasma and more gas containing C iv and N v than in the Carina OB1 association at z  = 0 kpc. Abundances and physical conditions are presented for many absorption components. The high ion absorption traces cooling transition temperature plasma probably driven by the outflowing hot gas, while the extraordinarily large thermal pressure, p / k  ∼ 10{sup 5} cm{sup −3} K{sup −1}, in an absorption component at −114 km s{sup −1} probably arises from the ram pressure of the outflowing hot gas. The observations are consistent with a flow whose ionization structure in the high ions can be understood through a combination of nonequilibrium radiative cooling and turbulent mixing.

Whole genome sequencing for the molecular characterization of carbapenem-resistant Klebsiella pneumoniae strains isolated at the Italian ASST Fatebenefratelli Sacco Hospital, 2012-2014.

Science.gov (United States)

Rimoldi, Sara Giordana; Gentile, Bernardina; Pagani, Cristina; Di Gregorio, Annamaria; Anselmo, Anna; Palozzi, Anna Maria; Fortunato, Antonella; Pittiglio, Valentina; Ridolfo, Anna Lisa; Gismondo, Maria Rita; Rizzardini, Giuliano; Lista, Florigio

2017-10-10

The emergence of carbapenem-resistant Klebsiella pneumoniae strains is threatening antimicrobial treatment. Sixty-eight carbapenemase-producing K. pneumoniae strains isolated at Luigi Sacco University Hospital-ASST Fatebenefratelli Sacco (Milan, Italy) between 2012 and 2014 were characterised microbiologically and molecularly. They were tested for drug susceptibility and carbapenemase phenotypes, investigated by means of repetitive extra-genic palindromic polymerase chain reaction (REP-PCR), and fully sequenced by means of next-generation sequencing for the in silico analysis of multi-locus sequence typing (MLST), their resistome, virulome and plasmid content, and their core single nucleotide polymorphism (SNP) genotypes. All of the samples were resistant to carbapenems, other β-lactams and ciprofloxacin; many were resistant to aminoglycosides and tigecycline; and seven were resistant to colistin. Resistome analysis revealed the presence of blaKPC genes and, less frequently blaSHV, blaTEM, blaCTX-M and blaOXA, which are related to resistance to carbapenem and other β-lactams. Other genes conferring resistance to aminoglycoside, fluoroquinolone, phenicol, sulphonamide, tetracycline, trimethoprim and macrolide-lincosamide-streptogramin were also detected. Genes related to AcrAB-TolC efflux pump-dependent and pump-independent tigecycline resistance mechanisms were investigated, but it was not possible to clearly correlate the genomic features with tigecycline resistance because of the presence of a common mutation in susceptible, intermediate and resistant strains. Concerning colistin resistance, the mgrB gene was disrupted by an IS5-like element, and the mobile mcr-1 and mcr-2 genes were not detected in two cases. The virulome profile revealed type-3 fimbriae and iron uptake system genes, which are important during the colonisation stage in the mammalian host environment. The in silico detected plasmid replicons were classified as IncFIB(pQil), IncFIB(K), Col

Prevalencia de bacterias Gram negativas portadoras del gen blaKPC en hospitales de Colombia

Directory of Open Access Journals (Sweden)

Robinson Pacheco

2014-04-01

Full Text Available Introducción. Las enzimas carbapenemasas de tipo KPC tienen gran capacidad de diseminación, son causantes de epidemias y se asocian a mayor mortalidad y estancia hospitalaria. En Colombia se han venido reportando cada vez más desde 2007, pero se desconoce la prevalencia hospitalaria. Objetivo. Estimar la prevalencia hospitalaria del gen blaKPC. Materiales y métodos. Se evaluó la presencia del gen blaKPC y su ‘clonalidad’ en aislamientos de enterobacterias y Pseudomonas aeruginosa de pacientes hospitalizados. Resultados. De los 424 aislamientos evaluados durante el periodo de estudio, 273 cumplieron con criterios de elegibilidad, 31,1 % fue positivo para el gen blaKPC y, al ajustar por ‘clonalidad’, la positividad fue de 12,8 %. El gen blaKPC se encontró con mayor frecuencia en Klebsiella pneumoniae seguido de P. aeruginosa y otras enterobacterias. A pesar de que la unidad de cuidados intensivos aportó el mayor número de aislamientos, no se encontró un patrón más prevalente del gen blaKPC en las ellas que en las otras salas. El aparato respiratorio fue el sitio anatómico de origen con la mayor prevalencia. No se presentó estacionalidad en la frecuencia de los aislamientos portadores del gen blaKPC. Conclusión. Este estudio reveló la alta prevalencia del gen blaKPC en diferentes microorganismos aislados en varias instituciones hospitalarias del país. La extraordinaria capacidad de propagación del gen blaKPC, las dificultades del diagnóstico y la limitada disponibilidad de antibióticos plantean la apremiante necesidad de fortalecer los sistemas de vigilancia epidemiológica y ajustar oportunamente las políticas institucionales de uso racional de antibióticos con el fin de contener su diseminación a otras instituciones de salud del país.

A Carbapenem-Resistant Pseudomonas aeruginosa Isolate Harboring Two Copies of blaIMP-34 Encoding a Metallo-β-Lactamase.

Directory of Open Access Journals (Sweden)

Tatsuya Tada

Full Text Available A carbapenem-resistant strain of Pseudomonas aeruginosa, NCGM1984, was isolated in 2012 from a hospitalized patient in Japan. Immunochromatographic assay showed that the isolate was positive for IMP-type metallo-β-lactamase. Complete genome sequencing revealed that NCGM1984 harbored two copies of blaIMP-34, located at different sites on the chromosome. Each blaIMP-34 was present in the same structures of the class 1 integrons, tnpA(ISPa7-intI1-qacG-blaIMP-34-aac(6'-Ib-qacEdelta1-sul1-orf5-tniBdelta-tniA. The isolate belonged to multilocus sequence typing ST235, one of the international high-risk clones. IMP-34, with an amino acid substitution (Glu126Gly compared with IMP-1, hydrolyzed all β-lactamases tested except aztreonam, and its catalytic activities were similar to IMP-1. This is the first report of a clinical isolate of an IMP-34-producing P. aeruginosa harboring two copies of blaIMP-34 on its chromosome.

Evaluating the Impact of Antibiotic Exposures as Time-Dependent Variables on the Acquisition of Carbapenem-Resistant Acinetobacter baumannii.

Science.gov (United States)

Munoz-Price, L Silvia; Rosa, Rossana; Castro, Jose G; Laowansiri, Panthipa; Latibeaudiere, Rachel; Namias, Nicholas; Tarima, Sergey

2016-10-01

To determine the time-dependent effect of antibiotics on the initial acquisition of carbapenem-resistant Acinetobacter baumannii. Retrospective cohort study. Forty-bed trauma ICU in Miami, FL. All consecutive patients admitted to the unit from November 1, 2010, to November 30, 2011. None. Patients underwent surveillance cultures at admission to the unit and weekly thereafter. The primary outcome was the acquisition of carbapenem-resistant A. baumannii on surveillance cultures. Daily antibiotic exposures during the time of observation were used to construct time-dependent variables, including cumulative exposures (in grams and daily observed doses [defined daily doses]). Among 360 patients, 45 (12.5%) became colonized with carbapenem-resistant A. baumannii. Adjusted Cox models showed that each additional point in the Acute Physiologic and Chronic Health Evaluation score increased the hazard by 4.8% (hazard ratio, 1.048; 95% CI, 1.010-1.087; p = 0.0124) and time-dependent exposure to carbapenems quadrupled the hazard (hazard ratio, 4.087; 95% CI, 1.873-8.920; p = 0.0004) of acquiring carbapenem-resistant A. baumannii. Additionally, adjusted Cox models determined that every additional carbapenem defined daily dose increased the hazard of acquiring carbapenem-resistant A. baumannii by 5.1% (hazard ratio, 1.051; 95% CI, 1.007-1.093; p = 0.0243). Carbapenem exposure quadrupled the hazards of acquiring A. baumannii even after controlling for severity of illness.

PHARMACOEPIDEMIOLOGY OF CARBAPENEMS APPLICATION AMONG THE PREMATURE NEWBORNS IN SAINT PETERSBURG. WORLD EXPERIENCE IN NEONATOLOGY

Directory of Open Access Journals (Sweden)

A.S. Kolbin

2008-01-01

Full Text Available Premature newborns are a high risk group in terms of the infection complications growth. therefore, it is highly urgent to choose the efficient and safe antibacterial medications for the given category of patients. The authors carried out a pharma coepidemiological study of the carbapenems application among 353 newborns with very low body weight at birth, as well as the literature analysis on the use of this medications group in compliance with the evidence based medicine. As a result, they showed that for the last 8 years the frequency of the carbapenems application in Saint-Petersburg among the newborns has grown from 10 to 52%. It is statistically accurate that imipenem/cilastatin was more often used to the amount of 25 mg/kg twice a day. In 71% of cases, carbapenems were applied in the form of the empiric therapy against the general bacterial infection in combination with vancomycin and/or metronidazole. Antibiotics proved to be safe. The literature analysis showed that there is no data, which would allow one to compare the efficiency of carbapenems with other antibiotics among the newborns based on the results of the meta analyses and randomized clinical studies. Nowadays, carbapenems demonstrated high efficiency and safety in the small clinical observations.Key words: carbapenems, imipenem, meropenem, newborns with very low body weight at birth.

Risk factors for carbapenem resistant bacteraemia and mortality due to gram negative bacteraemia in a developing country

International Nuclear Information System (INIS)

Kalam, K.; Kumar, S.; Ali, S.; Baqi, S.; Qamar, F.

2014-01-01

Objective: To identify the risk factors for carbapenem resistant bacteraemia and mortality due to gram negative bacteraemia in a developing country. Methods: A prospective cohort study was conducted at the Sindh Institute of Urology and Transplantation (SIUT) from June to October 2012. Hospitalized patients > 15 years of age with gram negative bacteraemia were included and followed for a period of 2 weeks for in hospital mortality. Data was collected and analyzed for 243 subjects. Multivariate analysis was used to determine the risk factors for carbapenem resistant bacteraemia and mortality due to gram negative bacteraemia. Crude and adjusted odds ratio and 95% CI are reported. Results: A total of 729 out of 1535 (47.5%) cultures were positive for gram negative isolates. Out of 243 subjects, 117 (48%) had an MDR isolate. Having an MDR isolate on culture (AOR, 2.33; 95% CI, 1.35 -4.0), having multiple positive cultures (AOR, 1.8; 95% CI, 0.94 -3.4) and stay in ICU >48 hours (AOR, 2.0 ; 95% CI, 1.12 -3.78) were identified as significant risk factors for mortality due to gram negative organisms. Risk factors for carbapenem resistant bacteraemia were age >50 years (AOR, 1.83; 95% CI, 1.0-3.5), septic shock on presentation (AOR 2.53; 95% CI, 1.03 -6.2) , ICU stay of >72 hours (AOR 2.40; 95% CI, 1.14-5.0) and receiving immunosuppressant medications (AOR 2.23; 95% CI, 0.74 - 6.7). Conclusion: There is a high burden of MDR and carbapenem resistant gram negative bacteraemia, with a high mortality rate. (author)

Transcriptional analysis of bla NDM-1 and copy number alteration under carbapenem stress

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Deepjyoti Paul

2017-02-01

Full Text Available Abstract Background New Delhi metallo beta-lactamase is known to compromise carbapenem therapy and leading to treatment failure. However, their response to carbapenem stress is not clearly known. Here, we have investigated the transcriptional response of bla NDM-1 and plasmid copy number alteration under carbapenem exposure. Methods Three bla NDM-1 harboring plasmids representing three incompatibility types (IncFIC, IncA/C and IncK were inoculated in LB broth with and without imipenem, meropenem and ertapenem. After each 1 h total RNA was isolated, immediately reverse transcribed into cDNA and quantitative real time PCR was used for transcriptional expression of bla NDM-1. Horizontal transferability and stability of the plasmids encoding bla NDM-1 were also determined. Changes in copy number of bla NDM-1 harboring plasmids under the exposure of different carbapenems were determined by real time PCR. Clonal relatedness among the isolates was determined by pulsed field gel electrophoresis. Results Under carbapenem stress over an interval of time there was a sharp variation in the transcriptional expression of bla NDM-1 although it did not follow a specific pattern. All bla NDM-1 carrying plasmids were transferable by conjugation. These plasmids were highly stable and complete loss was observed between 92nd to 96th serial passages when antibiotic pressure was withdrawn. High copy number of bla NDM-1 was found for IncF type plasmids compared to the other replicon types. Conclusion This study suggests that the single dose of carbapenem pressure does not significantly influence the expression of bla NDM-1 and also focus on the stability of this gene as well as the change in copy number with respect to the incompatible type of plasmid harboring resistance determinant.

Multidrug-Resistant CTX-M-(15, 9, 2- and KPC-2-Producing Enterobacter hormaechei and Enterobacter asburiae Isolates Possessed a Set of Acquired Heavy Metal Tolerance Genes Including a Chromosomal sil Operon (for Acquired Silver Resistance

Directory of Open Access Journals (Sweden)

Leonardo N. Andrade

2018-03-01

Full Text Available Bacterial resistance to antibiotics is concern in healthcare-associated infections. On the other hand, bacterial tolerance to other antimicrobials, like heavy metals, has been neglected and underestimated in hospital pathogens. Silver has long been used as an antimicrobial agent and it seems to be an important indicator of heavy metal tolerance. To explore this perspective, we searched for the presence of acquired silver resistance genes (sil operon: silE, silS, silR, silC, silF, silB, silA, and silP and acquired extended-spectrum cephalosporin and carbapenem resistance genes (blaCTX−M and blaKPC in Enterobacter cloacae Complex (EcC (n = 27 and Enterobacter aerogenes (n = 8 isolated from inpatients at a general hospital. Moreover, the genetic background of the silA (silver-efflux pump and the presence of other acquired heavy metal tolerance genes, pcoD (copper-efflux pump, arsB (arsenite-efflux pump, terF (tellurite resistance protein, and merA (mercuric reductase were also investigated. Outstandingly, 21/27 (78% EcC isolates harbored silA gene located in the chromosome. Complete sil operon was found in 19/21 silA-positive EcC isolates. Interestingly, 8/20 (40% E. hormaechei and 5/6 (83% E. asburiae co-harbored silA/pcoD genes and blaCTX−M−(15,2,or9 and/or blaKPC−2 genes. Frequent occurrences of arsB, terF, and merA genes were detected, especially in silA/pcoD-positive, multidrug-resistant (MDR and/or CTX-M-producing isolates. Our study showed co-presence of antibiotic and heavy metal tolerance genes in MDR EcC isolates. In our viewpoint, there are few studies regarding to bacterial heavy metal tolerance and we call attention for more investigations and discussion about this issue in different hospital pathogens.

Improved production of an enzyme that hydrolyses raw yam starch by Penicillium sp. S-22 using fed-batch fermentation.

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Sun, Hai-Yan; Ge, Xiang-Yang; Zhang, Wei-Guo

2006-11-01

A newly isolated strain, Penicillium sp. S-22, was used to produce an enzyme that hydrolyses raw yam starch [raw yam starch digesting enzyme (RYSDE)]. The enzyme activity and overall enzyme productivity were respectively 16 U/ml and 0.19 U/ml h in the batch culture. The enzyme activity increased to 85 U/ml by feeding of partially hydrolyzed raw yam starch. When a mixture containing partially hydrolyzed raw yam starch and peptone was fed by a pH-stat strategy, the enzyme activity reached 366 U/ml, 23-fold of that obtained in the batch culture, and the overall productivity reached 3.4 U/ml h, which was 18-fold of that in the batch culture.

Clinical study of carbapenem sensitive and resistant Gram-negative bacteremia in neutropenic and nonneutropenic patients: The first series from India.

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Ghafur, A K; Vidyalakshmi, P R; Kannaian, P; Balasubramaniam, R

2014-01-01

Carbapenem resistance is a growing global concern. There is a lack of published clinical studies on the topic from Indian subcontinent. Aim of this study was to analyze clinical profile of patients with carbapenem sensitive and resistant bacteremia among neutropenic and nonneutropenic patients. Retrospective analysis of 141 patients who had carbapenem resistant or sensitive Gram-negative bacteremia, identified over a period of 1-year was done by medical records review, in Apollo Specialty Hospital, a 300-bedded tertiary care Oncology, neurosurgical and orthopedic center in South India. Of the total 141 patients with Gram-negative bacteremia, 44 had carbapenem resistant ones. Of these 44 patients, 17 were neutropenics (resistant neutropenic group) and 27 nonneutropenic patients (resistant nonneutropenic group). Of the 97 patients with carbapenem sensitive bacteremia, 43 were neutropenic (sensitive neutropenic group) and 54 nonneutropenics (sensitive nonneutropenic group). The 28 days mortality was significantly higher in carbapenem resistant bacteremic group compared to the sensitive one (P = 0.008). This is the first study from India comparing clinical features of patients with carbapenem sensitive and resistant blood stream infections. Patients with carbapenem resistant bacteremia had higher mortality compared to patients with sensitive bacteremia.

Emergence and Evolution of Multidrug-Resistant Klebsiella pneumoniae with both blaKPC and blaCTX-M Integrated in the Chromosome.

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Huang, Weihua; Wang, Guiqing; Sebra, Robert; Zhuge, Jian; Yin, Changhong; Aguero-Rosenfeld, Maria E; Schuetz, Audrey N; Dimitrova, Nevenka; Fallon, John T

2017-07-01

The extended-spectrum-β-lactamase (ESBL)- and Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae represent serious and urgent threats to public health. In a retrospective study of multidrug-resistant K. pneumoniae , we identified three clinical isolates, CN1, CR14, and NY9, carrying both bla CTX-M and bla KPC genes. The complete genomes of these three K. pneumoniae isolates were de novo assembled by using both short- and long-read whole-genome sequencing. In CR14 and NY9, bla CTX-M and bla KPC were carried on two different plasmids. In contrast, CN1 had one copy of bla KPC-2 and three copies of bla CTX-M-15 integrated in the chromosome, for which the bla CTX-M-15 genes were linked to an insertion sequence, IS Ecp1 , whereas the bla KPC-2 gene was in the context of a Tn 4401a transposition unit conjugated with a PsP3-like prophage. Intriguingly, downstream of the Tn 4401a-bla KPC-2 -prophage genomic island, CN1 also carried a clustered regularly interspaced short palindromic repeat (CRISPR)- cas array with four spacers targeting a variety of K. pneumoniae plasmids harboring antimicrobial resistance genes. Comparative genomic analysis revealed that there were two subtypes of type I-E CRISPR- cas in K. pneumoniae strains and suggested that the evolving CRISPR- cas , with its acquired novel spacer, induced the mobilization of antimicrobial resistance genes from plasmids into the chromosome. The integration and dissemination of multiple copies of bla CTX-M and bla KPC from plasmids to chromosome depicts the complex pandemic scenario of multidrug-resistant K. pneumoniae Additionally, the implications from this study also raise concerns for the application of a CRISPR- cas strategy against antimicrobial resistance. Copyright © 2017 American Society for Microbiology.

Catalytic strategy used by the myosin motor to hydrolyze ATP.

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Kiani, Farooq Ahmad; Fischer, Stefan

2014-07-22

Myosin is a molecular motor responsible for biological motions such as muscle contraction and intracellular cargo transport, for which it hydrolyzes adenosine 5'-triphosphate (ATP). Early steps of the mechanism by which myosin catalyzes ATP hydrolysis have been investigated, but still missing are the structure of the final ADP·inorganic phosphate (Pi) product and the complete pathway leading to it. Here, a comprehensive description of the catalytic strategy of myosin is formulated, based on combined quantum-classical molecular mechanics calculations. A full exploration of catalytic pathways was performed and a final product structure was found that is consistent with all experiments. Molecular movies of the relevant pathways show the different reorganizations of the H-bond network that lead to the final product, whose γ-phosphate is not in the previously reported HPγO4(2-) state, but in the H2PγO4(-) state. The simulations reveal that the catalytic strategy of myosin employs a three-pronged tactic: (i) Stabilization of the γ-phosphate of ATP in a dissociated metaphosphate (PγO3(-)) state. (ii) Polarization of the attacking water molecule, to abstract a proton from that water. (iii) Formation of multiple proton wires in the active site, for efficient transfer of the abstracted proton to various product precursors. The specific role played in this strategy by each of the three loops enclosing ATP is identified unambiguously. It explains how the precise timing of the ATPase activation during the force generating cycle is achieved in myosin. The catalytic strategy described here for myosin is likely to be very similar in most nucleotide hydrolyzing enzymes.

A systematic review: can one prescribe carbapenems to patients with IgE-mediated allergy to penicillins or cephalosporins?

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Kula, Brittany; Djordjevic, Gordana; Robinson, Joan L

2014-10-15

Cross-reactivity between penicillins or cephalosporins and carbapenems is anticipated as all have a beta lactam ring. However, the true incidence of immunoglobulin (Ig)E-mediated cross-reactivity is not known. A systematic review was conducted to collect and combine all published data on children and adults reported to have a clinical history of IgE-mediated hypersensitivity to a penicillin and/or cephalosporin who were subsequently given a carbapenem. Reactions were classified as proven, suspected, or possible IgE-mediated and non-IgE-mediated. Ten studies and 12 case reports describing 854 participants fit the study criteria. For patients with previous proven, suspected, or possible IgE-mediated penicillin reactions (N = 838), the incidence of any type of suspected hypersensitivity reaction to a carbapenem was 36/838 (4.3%; 95% confidence interval [CI], 3.1%-5.9%) and the incidence of proven (1/838), suspected (0/838), or possible (19/838) IgE-mediated reactions was 20/838 (2.4%; 95% CI, 1.6%-3.7%). Of the subset of patients with positive penicillin skin tests (n = 295), only 1 had a hypersensitivity reaction (0.3%; 95% CI, .06%-1.9%), and this was a possible IgE-mediated reaction. For patients with previous proven, suspected, or possible IgE-mediated cephalosporin reactions (N = 12), the incidence of any type of hypersensitivity reaction to a carbapenem was 3/12 (25%); this included 2 non-IgE-mediated reactions and 1 possible IgE-mediated reaction. The cross-reactivity between penicillins and carbapenems for IgE-mediated reactions is very low, but caution is still advised. Cross-reactivity rates may be higher between cephalosporins and carbapenems; however, minimal data are available. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Invasive carbapenem-resistant Enterobacteriaceae infection at a ...

African Journals Online (AJOL)

Background. There are no paediatric reports of invasive infection caused by carbapenem-resistant Enterobacteriaceae (CRE) from Africa. Objectives. To document a series of cases of CRE infections at a tertiary children's hospital in Cape Town, South Africa, describing the clinical and microbiological findings in these ...

Production and storage of biohydrogen during sequential batch fermentation of Spirogyra hydrolyzate by Clostridium butyricum

International Nuclear Information System (INIS)

Ortigueira, Joana; Pinto, Tiago; Gouveia, Luísa; Moura, Patrícia

2015-01-01

The biological hydrogen production from Spirogyra sp. biomass was studied in a SBR (sequential batch reactor) equipped with a biogas collecting and storage system. Two acid hydrolysis pre-treatments (1N and 2N H 2 SO 4 ) were applied to the Spirogyra biomass and the subsequent fermentation by Clostridium butyricum DSM 10702 was compared. The 1N and 2N hydrolyzates contained 37.2 and 40.8 g/L of total sugars, respectively, and small amounts of furfural and HMF (hydroxymethylfurfural). These compounds did not inhibit the hydrogen production from crude Spirogyra hydrolyzates. The fermentation was scaled up to a batch operated bioreactor coupled with a collecting system that enabled the subsequent characterization and storage of the biogas produced. The cumulative hydrogen production was similar for both 1N and 2N hydrolyzate, but the hydrogen production rates were 438 and 288 mL/L.h, respectively, suggesting that the 1N hydrolyzate was more suitable for sequential batch fermentation. The SBR with 1N hydrolyzate was operated continuously for 13.5 h in three consecutive batches and the overall hydrogen production rate and yield reached 324 mL/L.h and 2.59 mol/mol, respectively. This corresponds to a potential daily production of 10.4 L H 2 /L Spirogyra hydrolyzate, demonstrating the excellent capability of C. butyricum to produce hydrogen from microalgal biomass. - Highlights: • Production of biohydrogen from crude Spirogyra hydrolyzates. • Set-up of a collecting and storage system for continuous biogas sampling. • The hydrogen production rate is 324 mL/L.h in the SBR (sequential batch reactor). • The SBR produces daily an equivalent to 10.4 L H 2 /L of crude Spirogyra hydrolyzate

Carbapenems to Treat Multidrug and Extensively Drug-Resistant Tuberculosis: A Systematic Review.

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Sotgiu, Giovanni; D'Ambrosio, Lia; Centis, Rosella; Tiberi, Simon; Esposito, Susanna; Dore, Simone; Spanevello, Antonio; Migliori, Giovanni Battista

2016-03-12

Carbapenems (ertapenem, imipenem, meropenem) are used to treat multidrug-resistant (MDR-) and extensively drug-resistant tuberculosis (XDR-TB), even if the published evidence is limited, particularly when it is otherwise difficult to identify the recommended four active drugs to be included in the regimen. No systematic review to date has ever evaluated the efficacy, safety, and tolerability of carbapenems. A search of peer-reviewed, scientific evidence was carried out, aimed at evaluating the efficacy/effectiveness, safety, and tolerability of carbapenem-containing regimens in individuals with pulmonary/extra-pulmonary disease which was bacteriologically confirmed as M/XDR-TB. We used PubMed to identify relevant full-text, English manuscripts up to the 20 December 2015, excluding editorials and reviews. Seven out of 160 studies satisfied the inclusion criteria: two on ertapenem, one on imipenem, and four on meropenem, all published between 2005 and 2016. Of seven studies, six were retrospective, four were performed in a single center, two enrolled children, two had a control group, and six reported a proportion of XDR-TB cases higher than 20%. Treatment success was higher than 57% in five studies with culture conversion rates between 60% and 94.8%. The safety and tolerability is very good, with the proportion of adverse events attributable to carbapenems below 15%.

Emergence and nosocomial spread of carbapenem-resistant OXA-232-producing Klebsiella pneumoniae in Brunei Darussalam

NARCIS (Netherlands)

Abdul Momin, Muhd Haziq Fikry; Liakopoulos, Apostolos; Phee, Lynette M.; Wareham, David W.

2017-01-01

Objectives Carbapenem-resistant Enterobacteriaceae (CRE) are identified as a major global health concern. The success of CRE is facilitated by the emergence, acquisition and spread of successful clones carrying plasmid-encoded resistance genes. In this study, an outbreak of carbapenem-resistant

Treatment Outcomes in Infections Caused by "SPICE" (Serratia, Pseudomonas, Indole-positive Proteus, Citrobacter, and Enterobacter) Organisms: Carbapenem versus Noncarbapenem Regimens.

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Moy, Stanley; Sharma, Roopali

2017-01-01

Techniques used to identify AmpC β-lactamases in SPICE (Serratia, Pseudomonas, indole-positive Proteus, Citrobacter, and Enterobacter) organisms are not yet optimized for the clinical laboratory and are not routinely used. Clinicians are often left with an uncertainty on the choice of antibiotic when a SPICE organism is isolated. The purpose of this study was to evaluate the outcomes of carbapenem versus noncarbapenem regimens in treating bacteremia or urinary tract infection from a SPICE organism in clinical practice. This single-center, retrospective, cohort study analyzed data from adult patients who had clinical infection with a SPICE organism isolated from blood or urine cultures. Patients were assigned to a carbapenem- or noncarbapenem-treated group. The primary end point was clinical response, defined as a resolution of signs and symptoms of infection at the end of therapy. A total of 332 patients were assessed, and 145 patients met the inclusion criteria for the study. There were 20 patients who received a carbapenem, while 125 received a noncarbapenem regimen. The percentage of patients who were bacteremic was 46.2%. Clinical response overall was achieved in 80% of patients on a carbapenem versus 90.3% of patients on a noncarbapenem regimen (P = 0.24). The rate of microbiologic cure was 90% in patients on a carbapenem versus 91.2% in patients on a noncarbapenem regimen (P = 1). In this study in patients treated for infection with a SPICE organism in clinical practice, the rates of clinical response did not differ significantly between the carbapenem and noncarbapenem groups. Current CLSI breakpoints set for SPICE organisms may still be reliable and may not require additional testing for AmpC β-lactamases. Copyright © 2017 Elsevier HS Journals, Inc. All rights reserved.

The Implementation of a Hospital-wide Practice for the Selective Use of Carbapenems Based on the Monitoring of Susceptibility of Pseudomonas aeruginosa Isolates.

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Ohshima, Toshio; Asai, Satomi; Miyazawa, Miki; Yamamoto, Yukari; Hisada, Akifumi; Kumazawa, Chie; Hashimoto, Masayoshi; Fukawa, Katsuji; Iwashita, Hideo; Umezawa, Kazuo; Yamada, Sanetoshi; Yamamoto, Yoshiro; Miyachi, Hayato

2017-12-20

To control carbapenem-resistant Pseudomonas aeruginosa, we implemented a hospital-wide policy concerning the selective use of carbapenems based on the monitoring of P. aeruginosa isolates for susceptibility to five carbapenems using a customized dry plate method. In this study, we retrospectively investigated the outcome of our measures to control carbapenem-resistant P. aeruginosa. To select effective carbapenems, 100 clinical isolates were collected, and the minimum inhibitory concentration (MIC) to 5 carbapenems (IPM/CS, MEPM, DRPM, BIPM and PAPM/BP) was monitored using a customized dry plate method from 2006 to 2013. Carbapenems, which were associated with a high rate of drug resistance in P. aeruginosa, were restricted from use during our intervention study. The antimicrobial use density per 100 bed-days (AUD 100 ) of carbapenems and the detection rates of carbapenem (IPM/CS and MEPM)-resistant P. aeruginosa were determined during the period of the intervention. The isolates consistently showed higher rates of drug-resistant P. aeruginosa in IPM/CS and PAPM/BP. Thus, DRPM, MEPM and BIPM were adopted for hospital-wide use. The detection rates of all IPM/Cs and MEPM-resistant P. aeruginosa significantly decreased. Meanwhile, the consumption of carbapenems showed an increasing trend. The outcome of the hospital-wide implementation of the selective use of carbapenems based on periodic monitoring of the susceptibility of P. aeruginosa isolates was retrospectively studied. Implementation of this measure might have contributed in part to the control of carbapenem-resistant P. aeruginosa in our hospital.

Enzymic lactose hydrolysis

Energy Technology Data Exchange (ETDEWEB)

Miller, J J; Brand, J C

1980-01-01

Acid or enzymic hydrolysis can be used to hydrolyze lactose. Advantages of both are compared and details of enzymic hydrolysis using yeast or fungal enzymes given. The new scheme outlined involves recycling lactase. Because lactose and lactase react to ultrafiltration (UF) membranes differently separation is possible. Milk or milk products are ultrafiltered to separate a concentrate from a lactose-rich permeate which is treated with lactase in a reactor until hydrolysis reaches a required level. The lactase can be removed by UF as it does not permeate the membrane, and it is recycled back to the reactor. Permeate from the second UF stage may or may not be recombined with the concentrate from the first stage to produce a low lactose product (analysis of a typical low-lactose dried whole milk is given). Batch or continuous processes are explained and a batch process without enzyme recovery is discussed. (Refs. 4).

Association between the Presence of Aminoglycoside-Modifying Enzymes and In Vitro Activity of Gentamicin, Tobramycin, Amikacin, and Plazomicin against Klebsiella pneumoniae Carbapenemase- and Extended-Spectrum-β-Lactamase-Producing Enterobacter Species.

Science.gov (United States)

Haidar, Ghady; Alkroud, Ammar; Cheng, Shaoji; Churilla, Travis M; Churilla, Bryce M; Shields, Ryan K; Doi, Yohei; Clancy, Cornelius J; Nguyen, M Hong

2016-09-01

We compared the in vitro activities of gentamicin (GEN), tobramycin (TOB), amikacin (AMK), and plazomicin (PLZ) against 13 Enterobacter isolates possessing both Klebsiella pneumoniae carbapenemase and extended-spectrum β-lactamase (KPC+/ESBL+) with activity against 8 KPC+/ESBL-, 6 KPC-/ESBL+, and 38 KPC-/ESBL- isolates. The rates of resistance to GEN and TOB were higher for KPC+/ESBL+ (100% for both) than for KPC+/ESBL- (25% and 38%, respectively), KPC-/ESBL+ (50% and 17%, respectively), and KPC-/ESBL- (0% and 3%, respectively) isolates. KPC+/ESBL+ isolates were more likely than others to possess an aminoglycoside-modifying enzyme (AME) (100% versus 38%, 67%, and 5%; P = 0.007, 0.06, and 1 AME than with ≤1 AME. The presence of at least 2/3 of KPC, SHV, and TEM predicted the presence of AMEs. PLZ MICs against all isolates were ≤4 μg/ml, regardless of KPC/ESBL pattern or the presence of AMEs. In conclusion, GEN and TOB are limited as treatment options against KPC+ and ESBL+ Enterobacter PLZ may represent a valuable addition to the antimicrobial armamentarium. A full understanding of AMEs and other aminoglycoside resistance mechanisms will allow clinicians to incorporate PLZ rationally into treatment regimens. The development of molecular assays that accurately and rapidly predict antimicrobial responses among KPC- and ESBL-producing Enterobacter spp. should be a top research priority. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

KPC and VIM producing Enterobacter cloacae strain from a hospital in northeastern Venezuela.

Science.gov (United States)

Martínez, Dianny; Marcano, Daniel; Rodulfo, Hectorina; Salgado, Nurys; Cuaical, Nirvia; Rodriguez, Lucy; Caña, Luisa; Medina, Belkis; Guzman, Militza; De Donato, Marcos

2015-06-01

An 83-year-old male patient is admitted to the central hospital in Cumana, Venezuela with severe urinary infection, history of hospitalizaions and prolonged antimicrobial treatments. A strain of Enterobacter cloacae was isolated showing resistance to multiple types of antibiotics (only sensitive to gentamicin), with phenotype of serine- and metallo-carbapenemases. Both, bla(VIM-2) and bla(KPC) genes were detected in the isolate. This is the first report of an Enterobacteriaceae species producing both KPC carbapenemase and VIM metallo carbapenemase in Venezuela. This finding has a great clinical and epidemiological impact in the region, because of the feasibility of transferring these genes, through mobile elements to other strains of Enterobacter and to other infection-causing species of bacteria.

Understanding the Role of Physical Properties of Cellulose on Its Hydrolyzability by Cellulases

Science.gov (United States)

O'Dell, Patrick Jonathan

Cellulose has long been explored as a potential feedstock for biofuel, however the recalcitrance of cellulose makes its conversion into biofuel much more challenging and economically unfavorable compared to well-established processes for converting starch or sugar feedstocks into biofuel. Enzymes capable of hydrolyzing cellulose into soluble sugars, glucose and cellobiose, have been found to work processively along cellulose microfibrils starting from reducing end groups. For this study, cellulose was produced and purified in-house from Gluconacetobacter xylinum cultures, and characterized by quantifying functional groups (aldehyde, ketone, and carboxyl groups) to determine the extent of oxidation of cellulose due to the processing steps. The main goal of this study was to look at the impacts of ultrasonication on cellulose's structure and the enzymatic hydrolyzability of cellulose. A completely randomized experimental design was used to test the effect of ultrasonication time and amplitude (intensity) on changes in cellulose fibril length, degree of polymerization, and rates and extents of hydrolysis. Results indicated that sonication time does significantly impact both the fibril length and average degree of polymerization of cellulose. The impact of ultrasonication on the hydrolyzability of cellulose by commercial cellulase and beta-glucosidase preparations could not be effectively resolved due to high variability in the experimental results. These studies serve as a basis for future studies understanding the role of cellulose microstructure in the mechanism of cellulase hydrolysis of cellulose.

Minocycline and Tigecycline: What Is Their Role in the Treatment of Carbapenem-Resistant Gram-Negative Organisms?

Science.gov (United States)

Shankar, Chaitra; Nabarro, Laura E B; Anandan, Shalini; Veeraraghavan, Balaji

2017-06-01

Carbapenem-resistant organisms are increasingly common worldwide, particularly in India and are associated with high mortality rates especially in patients with severe infection such as bacteremia. Existing drugs such as carbapenems and polymyxins have a number of disadvantages, but remain the mainstay of treatment. The tetracycline class of antibiotics was first produced in the 1940s. Minocycline, tetracycline derivative, although licensed for treatment of wide range of infections, has not been considered for treatment of multidrug-resistant organisms until recently and needs further in vivo studies. Tigecycline, a derivative of minocycline, although with certain disadvantages, has been frequently used in the treatment of carbapenem-resistant organisms. In this article, we review the properties of minocycline and tigecycline, the common mechanisms of resistance, and assess their role in the management of carbapenem-resistant organisms.

Investigation of viscosity of whole hydrolyze sweetened condensed milk

Directory of Open Access Journals (Sweden)

O. Kalinina

2015-05-01

Full Text Available Introduction. Рaper is aimed at developing of low-lactose (hydrolyzed sweetened condensed milk products technology for lactose intolerant people and for the whole population. Materials and methods: Rheological characteristics were determined on a Reotest device by the 2 nd method of viscometry Results and discussion. Reasonability of ß-galactosidase use for milk lactose hydrolyze during the production of canned products with sugar was proved in the previous works. This technology gives possibility to increase the quality of condensed canned foods, to reduce sugar concentration till 50 %, to increase dietary properties. Due to the reducing of saccharose mass part till 22 and 31 % the products had a liquid consistency that’s why was a necessity to increase the viscosity properties of condensed products. One of method to increase the product viscosity is inoculation of stabilization systems. Reasonability of the usage of stabilization system Bivicioc 1L was proved. The researches of viscosity determination in whole hydrolyzed sweetened condensed milk were shown in the work. Relations of viscosity of whole hydrolyzed condensed milk to the deformation rate were presented. Conclusions Viscosity indices of experimental samples in the fresh produced products and during storage are determined and justified.

Empiric Piperacillin-Tazobactam versus Carbapenems in the Treatment of Bacteraemia Due to Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae.

Science.gov (United States)

Ng, Tat Ming; Khong, Wendy X; Harris, Patrick N A; De, Partha P; Chow, Angela; Tambyah, Paul A; Lye, David C

2016-01-01

Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae are a common cause of bacteraemia in endemic countries and may be associated with high mortality; carbapenems are considered the drug of choice. Limited data suggest piperacillin-tazobactam could be equally effective. We aimed to compare 30-day mortality of patients treated empirically with piperacillin-tazobactam versus a carbapenem in a multi-centre retrospective cohort study in Singapore. Only patients with active empiric monotherapy with piperacillin-tazobactam or a carbapenem were included. A propensity score for empiric carbapenem therapy was derived and an adjusted multivariate analysis of mortality was conducted. A total of 394 patients had ESBL-Escherichia.coli and ESBL-Klebsiella pneumoniae bacteraemia of which 23.1% were community acquired cases. One hundred and fifty-one received initial active monotherapy comprising piperacillin-tazobactam (n = 94) or a carbapenem (n = 57). Patients who received carbapenems were less likely to have health-care associated risk factors and have an unknown source of bacteraemia, but were more likely to have a urinary source. Thirty-day mortality was comparable between those who received empiric piperacillin-tazobactam and a carbapenem (29 [30.9%] vs. 17 [29.8%]), P = 0.89). Those who received empiric piperacillin-tazobactam had a lower 30-day acquisition of multi-drug resistant and fungal infections (7 [7.4%] vs. 14 [24.6%]), Pcarbapenem.

Safety and clinical outcomes of carbapenem de-escalation as part of an antimicrobial stewardship programme in an ESBL-endemic setting.

Science.gov (United States)

Lew, Kaung Yuan; Ng, Tat Ming; Tan, Michelle; Tan, Sock Hoon; Lew, Ee Ling; Ling, Li Min; Ang, Brenda; Lye, David; Teng, Christine B

2015-04-01

To evaluate the safety and clinical outcomes of patients who received carbapenem de-escalation as guided by an antimicrobial stewardship programme (ASP) in a setting where ESBL-producing Enterobacteriaceae are endemic. Patients receiving meropenem or imipenem underwent a prospective ASP review for eligibility for de-escalation according to defined institutional guidelines. Patients in whom carbapenem was de-escalated or not de-escalated, representing the acceptance and rejection of the ASP recommendation, respectively, were compared. The primary outcome was the clinical success rate; secondary outcomes included the 30 day readmission and mortality rates, the duration of carbapenem therapy, the incidence of adverse drug reactions due to antimicrobials, the acquisition of carbapenem-resistant Gram-negative bacteria and the occurrence of Clostridium difficile-associated diarrhoea (CDAD). The de-escalation recommendations for 300 patients were evaluated; 204 (68.0%) were accepted. The patient demographics and disease severity were similar. The clinical success rates were similar [de-escalated versus not de-escalated, 183/204 (89.7%) versus 85/96 (88.5%), P=0.84], as was the survival at hospital discharge [173/204 (84.8%) versus 79/96 (82.3%), P=0.58]. In the de-escalated group, the duration of carbapenem therapy was shorter (6 versus 8 days, Pcarbapenem-resistant Acinetobacter baumannii acquisition [4/204 (2.0%) versus 7/96 (7.3%), P=0.042] and there was a lower incidence of CDAD [2/204 (1.0%) versus 4/96 (4.2%), P=0.081]. This study suggests that the ASP-guided de-escalation of carbapenems led to comparable clinical success, fewer adverse effects and a lower incidence of the development of resistance. This approach is safe and practicable, and should be a key component of an ASP. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

The outcome of non-carbapenem-based empirical antibacterial ...

African Journals Online (AJOL)

Background: Febrile neutropenia (FN) is generally a complication of cancer chemotherapy. Objective: ... Furthermore, non-carbapenem-based empirical therapy provides benefit in regard to cost-effectiveness and antimicrobial stewardship when local antibiotic resistance patterns of gram-negative bacteria are considered.

Biofilm Production in Carbapenem Resistant Isolates from Chronic Wound Infections

Directory of Open Access Journals (Sweden)

Swarna SR

2017-02-01

Full Text Available Biofilms are communities of microorganisms covered with extracellular polymeric substances. Such biofilm phenotype makes the microorganism resistant to antibiotics and plays a role in wound chronicity. This results in prolonged hospital stays in ICU, greater cost, and increased mortality. Methods: Pus swabs (59 were collected from a tertiary care hospital near Chennai were processed and identified using standard procedure followed by antibiotic susceptibility testing and identification of carbapenem resistance by Modified Hodge test as per CLSI guidelines. The biofilm formation was tested using plastic microtiter plate method. Results: Out of 59 pus swabs, 51 yielded growth with 69 isolates and 8 yielded no growth. Among the 69 isolates, 51 were GNB and 18 were GPC. Biofilm detection was noted in 84.31% (43/51 GNB isolates with 0.1% crystal violet whereas 100% (51/51 showed biofilm positive with 0.1% safranin. About 74.50% (38/51 isolates of GNB were carbapenem resistant by screening with disk diffusion method. Only 24% (6/25 of GNB isolates among Enterobacteriaceae were positive by Modified Hodge test method. Conclusion: The result shows the association of biofilm production among carbapenem resistant isolates obtained from chronic wound infections.

Prevalencia de bacterias Gram negativas portadoras del gen blaKPC en hospitales de Colombia

OpenAIRE

Robinson Pacheco; Lyda Osorio; Adriana M. Correa; Maria Virginia Villegas

2014-01-01

Introducción. Las enzimas carbapenemasas de tipo KPC tienen gran capacidad de diseminación, son causantes de epidemias y se asocian a mayor mortalidad y estancia hospitalaria. En Colombia se han venido reportando cada vez más desde 2007, pero se desconoce la prevalencia hospitalaria. Objetivo. Estimar la prevalencia hospitalaria del gen blaKPC. Materiales y métodos. Se evaluó la presencia del gen blaKPC y su ‘clonalidad’ en aislamientos de enterobacterias y Pseudomonas aeruginosa de p...

Isolation of Klebsiella pneumoniae strains with altered susceptibility to carbapenems not carbapenemase mediated

Directory of Open Access Journals (Sweden)

Franca Cian

2009-12-01

Full Text Available The spread of enterobacteria producing extended-spectrum ß-lactamases (ESBLs is sharply increasing in Italy, while the detection of isolates resistant to carbapenems is still sporadic. Isolates of Klebsiella pneumoniae resistant to all cephalosporins, aminoglycosides and fluoroquinolones have been isolated in Trieste since 2008. Because of the altered profile of resistance to carbapenems, these strains were reported as ESBL-negative and possible carbapenemases producer by the expert system, leaving tigecycline as the only therapeutic choice.The purpose of this study is the characterization of the mechanisms involved in resistance to carbapenems in these strains and the evaluation of a reliable and simple test for phenotypic confirmation of ESBL and/or carbapenemase production. 25 isolates of MDR K. pneumoniae were collected between October 2008 and May 2009, mainly from urinary samples of elderly patients hospitalized in medicine wards. Identification and susceptibility testing were performed using the Vitek 2 system.The double-disc (DD test was used to check the production of ESBLs, while imipenem and imipenem-EDTA synergy test was used to detect the production of metallo-ßlactamase (MBL. Carbapenemase activity was tested by an hydrolysis assay and the production of MBLs was also investigated by PCR. The DD synergy test highlighted the possible production of ESBLs in 18 out of 22 strains, considered as negative by Vitek. All ESBLs producers tested positive for the blaCTX-M-15 allele. Only one isolate was resistant to carbapenems and resulted positive for production of MBL by the phenotypic test.The crude extract showed carbapenemase activity inhibited by EDTA; PCR test gave positive result for a blaVIM-type allele. PCR analysis performed on representative isolates, followed by sequencing, showed that coding sequence of ompk35 was not functional. Results of this study confirmed the emergence of ESBL-positive strains of K. pneumoniae that

Identification of UDP glucosyltransferases from the aluminum-resistant tree Eucalyptus camaldulensis forming β-glucogallin, the precursor of hydrolyzable tannins.

Science.gov (United States)

Tahara, Ko; Nishiguchi, Mitsuru; Frolov, Andrej; Mittasch, Juliane; Milkowski, Carsten

2018-08-01

In the highly aluminum-resistant tree Eucalyptus camaldulensis, hydrolyzable tannins are proposed to play a role in internal detoxification of aluminum, which is a major factor inhibiting plant growth on acid soils. To understand and modulate the molecular mechanisms of aluminum detoxification by hydrolyzable tannins, the biosynthetic genes need to be identified. In this study, we identified and characterized genes encoding UDP-glucose:gallate glucosyltransferase, which catalyzes the formation of 1-O-galloyl-β-d-glucose (β-glucogallin), the precursor of hydrolyzable tannins. By homology-based cloning, seven full-length candidate cDNAs were isolated from E. camaldulensis and expressed in Escherichia coli as recombinant N-terminal His-tagged proteins. Phylogenetic analysis classified four of these as UDP glycosyltransferase (UGT) 84A subfamily proteins (UGT84A25a, -b, UGT84A26a, -b) and the other three as UGT84J subfamily proteins (UGT84J3, -4, -5). In vitro enzyme assays showed that the UGT84A proteins catalyzed esterification of UDP-glucose and gallic acid to form 1-O-galloyl-β-d-glucose, whereas the UGT84J proteins were inactive. Further analyses with UGT84A25a and -26a indicated that they also formed 1-O-glucose esters of other structurally related hydroxybenzoic and hydroxycinnamic acids with a preference for hydroxybenzoic acids. The UGT84A genes were expressed in leaves, stems, and roots of E. camaldulensis, regardless of aluminum stress. Taken together, our results suggest that the UGT84A subfamily enzymes of E. camaldulensis are responsible for constitutive production of 1-O-galloyl-β-d-glucose, which is the first step of hydrolyzable tannin biosynthesis. Copyright © 2018 Elsevier Ltd. All rights reserved.

CLUMPING AND THE INTERPRETATION OF kpc-SCALE MAPS OF THE INTERSTELLAR MEDIUM: SMOOTH H I AND CLUMPY, VARIABLE H{sub 2} SURFACE DENSITY

Energy Technology Data Exchange (ETDEWEB)

Leroy, Adam K. [National Radio Astronomy Observtory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Lee, Cheoljong [Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22904 (United States); Schruba, Andreas [California Institute for Technology, 1200 E California Blvd, Pasadena, CA 91125 (United States); Bolatto, Alberto [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Hughes, Annie; Sandstrom, Karin; Schinnerer, Eva; Walter, Fabian [Max Planck Institute fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Pety, Jerome [Institut de Radioastronomie Millimetrique, 300 Rue de la Piscine, F-38406 Saint Martin d' Heres (France)

2013-05-20

Many recent models consider the structure of individual interstellar medium (ISM) clouds as a way to explain observations of large parts of galaxies. To compare such models to observations, one must understand how to translate between surface densities observed averaging over large ({approx}kpc) scales and surface densities on the scale of individual clouds ({approx}pc scale), which are treated by models. We define a ''clumping factor'' that captures this translation as the ratio of the mass-weighted surface density, which is often the quantity of physical interest, to the area-weighted surface density, which is observed. We use high spatial resolution (sub-kpc) maps of CO and H I emission from nearby galaxies to measure the clumping factor of both atomic and molecular gas. The molecular and atomic ISM exhibit dramatically different degrees of clumping. As a result, the ratio H{sub 2}/H I measured at {approx}kpc resolution cannot be trivially interpreted as a cloud-scale ratio of surface densities. H I emission appears very smooth, with a clumping factor of only {approx}1.3. Based on the scarce and heterogeneous high-resolution data available, CO emission is far more clumped with a widely variable clumping factor, median {approx}7 for our heterogeneous data. Our measurements do not provide evidence for a universal mass-weighted surface density of molecular gas, but also cannot conclusively rule out such a scenario. We suggest that a more sophisticated treatment of molecular ISM structure, one informed by high spatial resolution CO maps, is needed to link cloud-scale models to kpc-scale observations of galaxies.

Diversity of carbapenemases in clinical isolates of Enterobacteriaceae in Croatia--the results of a multicentre study.

Science.gov (United States)

Zujić Atalić, V; Bedenić, B; Kocsis, E; Mazzariol, A; Sardelić, S; Barišić, M; Plečko, V; Bošnjak, Z; Mijač, M; Jajić, I; Vranić-Ladavac, M; Cornaglia, G

2014-11-01

Since the first carbapenem-resistant Klebsiella pneumoniae strain was isolated in 2008, Enterobacteriaceae with reduced susceptibility to one or more carbapenems have emerged sporadically in different geographical regions in Croatia. These observations gave rise to a multicenter study on carbapenem resistance in Enterobacteriaceae from Croatia. Fifty-seven carbapenem-non-susceptible strains of Enterobacteriaceae were collected during 2011-2012 from four large hospital centres in Croatia. Overall, 36 strains produced VIM-1 β-lactamase, three produced NDM-1, and one produced KPC-2. A high degree of clonal relatedness was observed in Enterobacter cloacae and Citrobacter freundii strains, in contrast to K. pneumoniae strains. BlaVIM genes were located within class1 integron which contained genes encoding resistance to aminoglycosides (aacA4 ). The study found strong association between blaVIM and qnrB6 and between blaNDM and qnrA6 genes. © 2014 The Authors Clinical Microbiology and Infection © 2014 European Society of Clinical Microbiology and Infectious Diseases.

mRNA decapping enzyme from ribosomes of Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Stevens, A.

1980-01-01

By use of [ 3 H]methyl-5'-capped [ 14 C]mRNA from yeast as a substrate, a decapping enzyme activity has been detected in enzyme fractions derived from a high salt wash of ribosomes of Saccharomyces cerevisiae. The product of the decapping reaction is [ 3 H]m 7 GDP. That the enzyme is not a non-specific pyrophosphatase is suggested by the finding that the diphosphate product, m 7 GpppA(G), and UDP-glucose are not hydrolyzed

A Novel IncA/C1 Group Conjugative Plasmid, Encoding VIM-1 Metallo-Beta-Lactamase, Mediates the Acquisition of Carbapenem Resistance in ST104 Klebsiella pneumoniae Isolates from Neonates in the Intensive Care Unit of V. Monaldi Hospital in Naples.

Science.gov (United States)

Esposito, Eliana P; Gaiarsa, Stefano; Del Franco, Mariateresa; Crivaro, Valeria; Bernardo, Mariano; Cuccurullo, Susanna; Pennino, Francesca; Triassi, Maria; Marone, Piero; Sassera, Davide; Zarrilli, Raffaele

2017-01-01

The emergence of carbapenemase producing Enterobacteriaceae has raised major public health concern. The aim of this study was to investigate the molecular epidemiology and the mechanism of carbapenem resistance acquisition of multidrug-resistant Klebsiella pneumoniae isolates from 20 neonates in the neonatal intensive care unit (NICU) of the V. Monaldi Hospital in Naples, Italy, from April 2015 to March 2016. Genotype analysis by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) identified PFGE type A and subtypes A1 and A2 in 17, 2, and 1 isolates, respectively, and assigned all isolates to sequence type (ST) 104. K. pneumoniae isolates were resistant to all classes of β-lactams including carbapenems, fosfomycin, gentamicin, and trimethoprim-sulfamethoxazole, but susceptible to quinolones, amikacin, and colistin. Conjugation experiments demonstrated that resistance to third-generation cephems and imipenem could be transferred along with an IncA/C plasmid containing the extended spectrum β-lactamase bla SHV -12 and carbapenem-hydrolyzing metallo-β-lactamase bla V IM-1 genes. The plasmid that we called pIncAC_KP4898 was 156,252 bp in size and included a typical IncA/C backbone, which was assigned to ST12 and core genome (cg) ST12.1 using the IncA/C plasmid MLST (PMLST) scheme. pIncAC_KP4898 showed a mosaic structure with bla V IM-1 into a class I integron, bla SHV -12 flanked by IS6 elements, a mercury resistance and a macrolide 2'-phosphotransferase clusters, ant(3″), aph(3″), aacA4, qnrA1, sul1 , and dfrA14 conferring resistance to aminoglycosides, quinolones, sulfonamides, and trimethoprim, respectively, several genes predicted to encode transfer functions and proteins involved in DNA transposition. The acquisition of pIncAC_KP4898 carrying bla V IM-1 and bla SHV -12 contributed to the spread of ST104 K. pneumoniae in the NICU of V. Monaldi Hospital in Naples.

A Novel IncA/C1 Group Conjugative Plasmid, Encoding VIM-1 Metallo-Beta-Lactamase, Mediates the Acquisition of Carbapenem Resistance in ST104 Klebsiella pneumoniae Isolates from Neonates in the Intensive Care Unit of V. Monaldi Hospital in Naples

Directory of Open Access Journals (Sweden)

Eliana P. Esposito

2017-11-01

Full Text Available The emergence of carbapenemase producing Enterobacteriaceae has raised major public health concern. The aim of this study was to investigate the molecular epidemiology and the mechanism of carbapenem resistance acquisition of multidrug-resistant Klebsiella pneumoniae isolates from 20 neonates in the neonatal intensive care unit (NICU of the V. Monaldi Hospital in Naples, Italy, from April 2015 to March 2016. Genotype analysis by pulsed-field gel electrophoresis (PFGE and multi-locus sequence typing (MLST identified PFGE type A and subtypes A1 and A2 in 17, 2, and 1 isolates, respectively, and assigned all isolates to sequence type (ST 104. K. pneumoniae isolates were resistant to all classes of β-lactams including carbapenems, fosfomycin, gentamicin, and trimethoprim–sulfamethoxazole, but susceptible to quinolones, amikacin, and colistin. Conjugation experiments demonstrated that resistance to third-generation cephems and imipenem could be transferred along with an IncA/C plasmid containing the extended spectrum β-lactamase blaSHV -12 and carbapenem-hydrolyzing metallo-β-lactamase blaV IM-1 genes. The plasmid that we called pIncAC_KP4898 was 156,252 bp in size and included a typical IncA/C backbone, which was assigned to ST12 and core genome (cg ST12.1 using the IncA/C plasmid MLST (PMLST scheme. pIncAC_KP4898 showed a mosaic structure with blaV IM-1 into a class I integron, blaSHV -12 flanked by IS6 elements, a mercury resistance and a macrolide 2′-phosphotransferase clusters, ant(3″, aph(3″, aacA4, qnrA1, sul1, and dfrA14 conferring resistance to aminoglycosides, quinolones, sulfonamides, and trimethoprim, respectively, several genes predicted to encode transfer functions and proteins involved in DNA transposition. The acquisition of pIncAC_KP4898 carrying blaV IM-1 and blaSHV -12 contributed to the spread of ST104 K. pneumoniae in the NICU of V. Monaldi Hospital in Naples.

Systematic review and meta-analysis of in vitro synergy of polymyxins and carbapenems.

Science.gov (United States)

Zusman, Oren; Avni, Tomer; Leibovici, Leonard; Adler, Amos; Friberg, Lena; Stergiopoulou, Theodouli; Carmeli, Yehuda; Paul, Mical

2013-10-01

Our objective was to examine the evidence of in vitro synergy of polymyxin-carbapenem combination therapy against Gram-negative bacteria (GNB). A systematic review and meta-analysis were performed. All studies examining in vitro interactions of antibiotic combinations consisting of any carbapenem with colistin or polymyxin B against any GNB were used. A broad search was conducted with no language, date, or publication status restrictions. Synergy rates, defined as a fractional inhibitory concentration index of ≤0.5 or a >2-log reduction in CFU, were pooled separately for time-kill, checkerboard, and Etest methods in a mixed-effect meta-analysis of rates. We examined whether the synergy rate depended on the testing method, type of antibiotic, bacteria, and resistance to carbapenems. Pooled rates with 95% confidence intervals (CI) are shown. Thirty-nine published studies and 15 conference proceeding were included, reporting on 246 different tests on 1,054 bacterial isolates. In time-kill studies, combination therapy showed synergy rates of 77% (95% CI, 64 to 87%) for Acinetobacter baumannii, 44% (95% CI, 30 to 59%) for Klebsiella pneumoniae, and 50% (95% CI, 30 to 69%) for Pseudomonas aeruginosa, with low antagonism rates for all. Doripenem showed high synergy rates for all three bacteria. For A. baumannii, meropenem was more synergistic than imipenem, whereas for P. aeruginosa the opposite was true. Checkerboard and Etest studies generally reported lower synergy rates than time-kill studies. The use of combination therapy led to less resistance development in vitro. The combination of a carbapenem with a polymyxin against GNB, especially A. baumannii, is supported in vitro by high synergy rates, with low antagonism and less resistance development. These findings should be examined in clinical studies.

Systematic Review and Meta-Analysis of In Vitro Synergy of Polymyxins and Carbapenems

Science.gov (United States)

Avni, Tomer; Leibovici, Leonard; Adler, Amos; Friberg, Lena; Stergiopoulou, Theodouli; Carmeli, Yehuda; Paul, Mical

2013-01-01

Our objective was to examine the evidence of in vitro synergy of polymyxin-carbapenem combination therapy against Gram-negative bacteria (GNB). A systematic review and meta-analysis were performed. All studies examining in vitro interactions of antibiotic combinations consisting of any carbapenem with colistin or polymyxin B against any GNB were used. A broad search was conducted with no language, date, or publication status restrictions. Synergy rates, defined as a fractional inhibitory concentration index of ≤0.5 or a >2-log reduction in CFU, were pooled separately for time-kill, checkerboard, and Etest methods in a mixed-effect meta-analysis of rates. We examined whether the synergy rate depended on the testing method, type of antibiotic, bacteria, and resistance to carbapenems. Pooled rates with 95% confidence intervals (CI) are shown. Thirty-nine published studies and 15 conference proceeding were included, reporting on 246 different tests on 1,054 bacterial isolates. In time-kill studies, combination therapy showed synergy rates of 77% (95% CI, 64 to 87%) for Acinetobacter baumannii, 44% (95% CI, 30 to 59%) for Klebsiella pneumoniae, and 50% (95% CI, 30 to 69%) for Pseudomonas aeruginosa, with low antagonism rates for all. Doripenem showed high synergy rates for all three bacteria. For A. baumannii, meropenem was more synergistic than imipenem, whereas for P. aeruginosa the opposite was true. Checkerboard and Etest studies generally reported lower synergy rates than time-kill studies. The use of combination therapy led to less resistance development in vitro. The combination of a carbapenem with a polymyxin against GNB, especially A. baumannii, is supported in vitro by high synergy rates, with low antagonism and less resistance development. These findings should be examined in clinical studies. PMID:23917322

Reduced protein carbonylation of cube steak and catfish fillet using antioxidative coatings containing cheddar whey, casein hydrolyzate and oolong tea extract

Science.gov (United States)

Hydrolysis of casein using chymotrypsin results in the formation of polypeptides (casein hydrolyzate, CH) with a hydrophobic aromatic amino acid on one end of the chain because the enzyme selectively cleaves the adjacent peptide-bond. Due to resonance of the aromatic micro-domain, thiols become redo...

Development of carbapenem resistance in Pseudomonas aeruginosa is associated with OprD polymorphisms, particularly the amino acid substitution at codon 170.

Science.gov (United States)

Shu, Jwu-Ching; Kuo, An-Jing; Su, Lin-Hui; Liu, Tsui-Ping; Lee, Ming-Hsun; Su, I-Ning; Wu, Tsu-Lan

2017-09-01

Pan-susceptible Pseudomonas aeruginosa (PSPA) clinical isolates carrying an OprD with loop 7 shortening (the group-1A allele) were found to rapidly develop carbapenem resistance under continuous selection pressure. We further studied whether OprD polymorphisms are associated with the potential to develop carbapenem resistance. OprD amino acid sequences of 126 PSPA clinical isolates were analysed to determine their STs using P. aeruginosa strain PAO1 as the control strain. Site-directed mutagenesis was performed in PAO1 to generate polymorphisms of interest. A disc diffusion method was used to select carbapenem-resistant variants from the mutant strains. Expression levels of oprD were determined by quantitative RT-PCR. MICs of carbapenems were determined by Etest. Forty-eight (38.1%) of the tested isolates carried the group-1A allele. Another two major STs, C1 and C2, both of which harboured an F170L polymorphism, were found in 21 (16.7%) and 39 (31.0%) isolates, respectively. The PAO1 type was also found in 14 (11.1%) isolates. Under continuous selective pressure, isolates of most STs developed carbapenem resistance at different numbers of passaging events; only those belonging to the PAO1 type remained susceptible. However, PAO1 mutants carrying either the oprD group-1A allele or the OprD-F170L polymorphism were able to develop carbapenem resistance. Reduced oprD expression triggered by continuous imipenem challenge was found in PAO1 mutants, but not in the PAO1 WT strain. OprD polymorphisms, particularly the F170L substitution and the specific shortening in loop 7, appear to determine the potential for P. aeruginosa to develop carbapenem resistance. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Characterization of Cellulase Enzyme Inhibitors Formed During the Chemical Pretreatments of Rice Straw

Science.gov (United States)

Rajan, Kalavathy

Production of fuels and chemicals from a renewable and inexpensive resource such as lignocellulosic biomass is a lucrative and sustainable option for the advanced biofuel and bio-based chemical platform. Agricultural residues constitute the bulk of potential feedstock available for cellulosic fuel production. On a global scale, rice straw is the largest source of agricultural residues and is therefore an ideal crop model for biomass deconstruction studies. Lignocellulosic biofuel production involves the processes of biomass conditioning, enzymatic saccharification, microbial fermentation and ethanol distillation, and one of the major factors affecting its techno-economic feasibility is the biomass recalcitrance to enzymatic saccharification. Preconditioning of lignocellulosic biomass, using chemical, physico-chemical, mechanical and biological pretreatments, is often practiced such that biomass becomes available to downstream processing. Pretreatments, such as dilute acid and hot water, are effective means of biomass conversion. However, despite their processing importance, preconditioning biomass also results in the production of carbohydrate and lignin degradation products that are inhibitory to downstream saccharification enzymes. The saccharification enzyme cocktail is made up of endo-cellulase, exo-cellulase and beta-glucosidase enzymes, whose role is to cleave cellulose polymers into glucose monomers. Specifically, endo-cellulase and exo-cellulase enzymes cleave cellulose chains in the middle and at the end, resulting in cellobiose molecules, which are hydrolyzed into glucose by beta-glucosidase. Unfortunately, degradation compounds generated during pretreatment inhibit the saccharification enzyme cocktail. Various research groups have identified specific classes of inhibitors formed during biomass pretreatment and have studied their inhibitory effect on the saccharification cocktail. These various research groups prepared surrogate solutions in an attempt to

Clinical evaluation of the need for carbapenems to treat community-acquired and healthcare-associated pneumonia.

Science.gov (United States)

Kamata, Kazuhiro; Suzuki, Hiromichi; Kanemoto, Koji; Tokuda, Yasuharu; Shiotani, Seiji; Hirose, Yumi; Suzuki, Masatsune; Ishikawa, Hiroichi

2015-08-01

Carbapenems have an overall broad antibacterial spectrum and should be protected against from the acquisition of drug resistance. The clinical advantages of carbapenem in cases of pneumonia have not been certified and the need for antipseudomonal antimicrobial agents to treat healthcare-associated pneumonia (HCAP) remains controversial. We introduced an antimicrobial stewardship program for carbapenem and tazobactam/piperacillin use and investigated the effects of this program on the clinical outcomes of 591 pneumonia cases that did not require intensive care unit management, mechanical ventilation or treatment with vasopressor agents [221 patients with community-acquired pneumonia (CAP) and 370 patients with HCAP]. Compared with the pre-intervention period, age, comorbidities and the severity and etiology of pneumonia did not differ during the intervention period. Carbapenems were rarely used during the intervention period in cases of pneumonia (CAP: 12% vs. 1%, HCAP: 13% vs. 1%), while antipseudomonal beta-lactam use was reduced from 33% to 8% among cases with HCAP. This reduction in the rate of carbapenem administration did not have an impact on the prognosis in the cases of CAP, and the in-hospital mortality was lower among the patients with HCAP during the intervention period (15% vs. 5%, p = 0.013). The causes of death in the cases of HCAP were not directly related to pneumonia during the intervention period. The current study shows that carbapenem use can be avoided in cases of CAP or HCAP that are not in a critical condition. The frequent use of antipseudomonal beta-lactams does not improve the clinical outcomes of HCAP. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Outbreak of carbapenem-resistant Providencia rettgeri in a tertiary ...

African Journals Online (AJOL)

2017-01-31

Jan 31, 2017 ... discharged, transmission from inanimate objects and healthcare workers is a ... Isolation of carbapenem-resistant NDM-1-positive Providencia rettgeri in Mexico. ... Australian Commission on Safety and Quality in Health Care.

In vitro activity of colistin in antimicrobial combination against carbapenem-resistant Acinetobacter baumannii isolated from patients with ventilator-associated pneumonia in Vietnam.

Science.gov (United States)

Le Minh, Vien; Thi Khanh Nhu, Nguyen; Vinh Phat, Voong; Thompson, Corinne; Huong Lan, Nguyen Phu; Thieu Nga, Tran Vu; Thanh Tam, Pham Thi; Tuyen, Ha Thanh; Hoang Nhu, Tran Do; Van Hao, Nguyen; Thi Loan, Huynh; Minh Yen, Lam; Parry, Christopher M; Trung Nghia, Ho Dang; Campbell, James I; Hien, Tran Tinh; Thwaites, Louise; Thwaites, Guy; Van Vinh Chau, Nguyen; Baker, Stephen

2015-10-01

Acinetobacter baumannii has become one of the major infection threats in intensive care units (ICUs) globally. Since 2008, A. baumannii has been the leading cause of ventilator-associated pneumonia (VAP) in our ICU at an infectious disease hospital in southern Vietnam. The emergence of this pathogen in our setting is consistent with the persistence of a specific clone exhibiting resistance to carbapenems. Antimicrobial combinations may be a strategy to treat infections caused by these carbapenem-resistant A. baumannii. Therefore, we assessed potential antimicrobial combinations against local carbapenem-resistant A. baumannii by measuring in vitro interactions of colistin with four antimicrobials that are locally certified for treating VAP. We first performed antimicrobial susceptibility testing and multilocus variable number tandem repeat analysis (MLVA) genotyping on 74 A. baumannii isolated from quantitative tracheal aspirates from patients with VAP over an 18-month period. These 74 isolates could be subdivided into 21 main clusters by MLVA and >80 % were resistant to carbapenems. We selected 56 representative isolates for in vitro combination synergy testing. Synergy was observed in four (7 %), seven (13 %), 20 (36 %) and 38 (68 %) isolates with combinations of colistin with ceftazidime, ceftriaxone, imipenem and meropenem, respectively. Notably, more carbapenem-resistant A. baumannii isolates (36/43; 84 %) exhibited synergistic activity with a combination of colistin and meropenem than carbapenem-susceptible A. baumannii isolates (2/13; 15 %) (P = 0.023; Fisher's exact test). Our findings suggest that combinations of colistin and meropenem should be considered when treating carbapenem-resistant A. baumannii infections in Vietnam, and we advocate clinical trials investigating combination therapy for VAP.

Increasing Resistance to Extended-Spectrum Cephalosporins, Fluoroquinolone, and Carbapenem in Gram-Negative Bacilli and the Emergence of Carbapenem Non-Susceptibility in Klebsiella pneumoniae: Analysis of Korean Antimicrobial Resistance Monitoring System (KARMS) Data From 2013 to 2015.

Science.gov (United States)

Kim, Dokyun; Ahn, Ji Young; Lee, Chae Hoon; Jang, Sook Jin; Lee, Hyukmin; Yong, Dongeun; Jeong, Seok Hoon; Lee, Kyungwon

2017-05-01

National surveillance of antimicrobial resistance becomes more important for the control of antimicrobial resistance and determination of treatment guidelines. We analyzed Korean Antimicrobial Resistance Monitoring System (KARMS) data collected from 2013 to 2015. Of the KARMS participants, 16 secondary or tertiary hospitals consecutively reported antimicrobial resistance rates from 2013 to 2015. Data from duplicate isolates and institutions with fewer than 20 isolates were excluded. To determine the long-term trends, previous KARMS data from 2004 to 2012 were also considered. The prevalence of methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium from 2013 to 2015 was 66-72% and 29-31%, respectively. The resistance rates of Escherichia coli to cefotaxime and cefepime gradually increased to 35% and 31%, respectively, and fluoroquinolone resistance reached 48% in 2015. The resistance rates of Klebsiella pneumoniae to cefotaxime, cefepime, and carbapenem were 38-41%, 33-41%, and carbapenem susceptibility rates of E. coli and K. pneumoniae decreased from 100% and 99.3% in 2011 to 99.0% and 97.0% in 2015, respectively. The resistance rate of Pseudomonas aeruginosa to carbapenem increased to 35% and the prevalence of carbapenem-resistant Acinetobacter baumannii increased from 77% in 2013 to 85% in 2015. Between 2013 and 2015, the resistance rates of E. coli to third- and fourth-generation cephalosporins increased continuously, while carbapenem-susceptibility gradually decreased, particularly in K. pneumoniae. The prevalence of carbapenem-resistant P. aeruginosa and A. baumannii increased significantly; therefore, few treatment options remain for these resistant strains. © The Korean Society for Laboratory Medicine

Low Frequency of Ceftazidime-Avibactam Resistance among Enterobacteriaceae Isolates Carrying blaKPC Collected in U.S. Hospitals from 2012 to 2015.

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Castanheira, Mariana; Mendes, Rodrigo E; Sader, Helio S

2017-03-01

Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae isolates have been increasingly reported worldwide, and therapeutic options to treat infections caused by these organisms are limited. We evaluated the activity of ceftazidime-avibactam and comparators against 456 Enterobacteriaceae isolates carrying bla KPC collected from 79 U.S. hospitals during 2012 to 2015. Overall, ceftazidime-avibactam (MIC 50/90 , 0.5/2 μg/ml; 99.3% susceptible) and tigecycline (MIC 50/90 , 0.5/1 μg/ml; 98.9% susceptible at ≤2 μg/ml) were the most active agents. Only 80.5% and 59.0% of isolates were susceptible to colistin and amikacin, respectively. All three isolates (0.7%) displaying resistance to ceftazidime-avibactam ( K. pneumoniae ; MICs, ≥16 μg/ml) were evaluated using whole-genome sequencing analysis and relative quantification of expression levels of porins and efflux pump. Two isolates carried metallo-β-lactamase genes, bla NDM-1 or bla VIM-4 , among other β-lactam resistance mechanisms, and one displayed a premature stop codon in ompK35 and decreased expression of ompK36 Ceftazidime-avibactam was active against 100.0 and 99.3% of isolates carrying bla KPC-3 ( n = 221) and bla KPC-2 ( n = 145), respectively. Isolates carrying bla KPC were more commonly recovered from pneumonia ( n = 155), urinary tract ( n = 93), and skin/soft tissue ( n = 74) infections. Ceftazidime-avibactam (97.8 to 100.0% susceptible) was consistently active against isolates from all infection sites. K. pneumoniae (83.3% of the collection) susceptibility rates were 99.2% for ceftazidime-avibactam, 98.9% for tigecycline, and 80.1% for colistin. Ceftazidime-avibactam susceptibility did not vary substantially when comparing isolates from intensive care unit (ICU) patients to those from non-ICU patients. Ceftazidime-avibactam was active against this large collection of isolates carrying bla KPC and represents a valuable addition to the armamentarium currently available for the

OXA beta-lactamase-mediated carbapenem resistance in Acinetobacter baumannii

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S M Amudhan

2011-01-01

Full Text Available Objectives: Acinetobacter baumannii is a significant pathogen in health care settings. In recent years, an increase in carbapenem resistance among A. baumannii due to Ambler class B metallo-beta-lactamases or class D OXA carbapenamases has been reported. In this study we detected the presence of OXA carbapenamases and coproduction of metallo-beta-lactamases (blaVIM and blaIMP by phenotypic and genotypic methods in carbapenem resistant clinical isolates of Acinetobacter baumannii. Materials and Methods: A total of 116 consecutive, non-duplicate carbapenem resistant A. baumannii isolated from various clinical specimens were included in the study. The modified Hodge test and inhibitor potentiated disk diffusion tests were done for the screening of carbapenamase and metallo-beta-lactamase production, respectively. Polymerase chain reaction (PCR was performed for the detection of OXA (blaOXA 23 like, blaOXA 24 like, blaOXA-51 like and blaOXA-58 like genes and metallo-beta-lactamases (blaVIM and blaIMP genes. Gene sequencing was performed for representative isolates. Results: Among 116 A. baumannii, OXA genes were detected in 106 isolates. BlaOXA 51 like (n = 99 and blaOXA -23 like (n = 95 were the most common and they coexisted in 89 isolates. blaOXA-24 like gene was detected in two isolates of which one also carried blaOXA-51 like and blaOXA-58 like genes. The modified Hodge test was positive in 113 isolates. The metallo-beta-lactamase screening test was positive in 92 isolates. blavim was detected in 54 isolates of which 1 also carried the blaIMP gene. Conclusions: blaOXA-23 like and bla OXA 51 like genes are the most common types of OXA carbapenamases while the blaVIM type is the most common type of metallo-beta-lactamase contributing to carbapenem resistance in clinical isolates of A. baumannii. The coproduction of OXA and metallo-beta-lactamases is not an uncommon phenomenon in A. baumannii.

Isolation of dextran-hydrolyzing intestinal bacteria and characterization of their dextranolytic activities.

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Kim, Jin Kyoung; Shin, So-Yeon; Moon, Jin Seok; Li, Ling; Cho, Seung Kee; Kim, Tae-Jip; Han, Nam Soo

2015-06-01

The aim of this study was to isolate dextran-hydrolyzing bacteria from the human intestines and to identify their dextranolytic enzymes. For this, dextranase-producing microorganisms were screened from fecal samples by using blue dextran-containing media. Colonies producing a decolorized zone were isolated and they were grouped using RAPD-PCR. 16S rRNA gene sequencing analysis revealed the isolates were Bacteroides (B.) thetaiotaomicron, B. ovatus, B. vulgatus, B. dorei, B. xylanisolvens, B. uniformis, and Veillonella (V.) rogosae. Thin layer chromatography analysis showed that the dextranases exhibit mainly endo-type activity and produce various oligosaccharides including isomaltose and isomaltotriose. Zymogram analysis demonstrated that enzymes localized mainly in the cell membrane fraction and the molecular weight was 50-70 kDa. When cultured in a dextran-containing medium, all strains isolated in this study produced short-chain fatty acids, with butyric acid as the major compound. This is the first study to report that human intestinal B. xylanisolvens, B. dorei, and V. rogosae metabolize dextran utilizing dextranolytic enzymes. © 2015 Wiley Periodicals, Inc.

Phylloquinone (vitamin K(1) ) biosynthesis in plants: two peroxisomal thioesterases of Lactobacillales origin hydrolyze 1,4-dihydroxy-2-naphthoyl-CoA.

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Widhalm, Joshua R; Ducluzeau, Anne-Lise; Buller, Nicole E; Elowsky, Christian G; Olsen, Laura J; Basset, Gilles J C

2012-07-01

It is not known how plants cleave the thioester bond of 1,4-dihydroxy-2-naphthoyl-CoA (DHNA-CoA), a necessary step to form the naphthoquinone ring of phylloquinone (vitamin K(1) ). In fact, only recently has the hydrolysis of DHNA-CoA been demonstrated to be enzyme driven in vivo, and the cognate thioesterase characterized in the cyanobacterium Synechocystis. With a few exceptions in certain prokaryotic (Sorangium and Opitutus) and eukaryotic (Cyanidium, Cyanidioschyzon and Paulinella) organisms, orthologs of DHNA-CoA thioesterase are missing outside of the cyanobacterial lineage. In this study, genomic approaches and functional complementation experiments identified two Arabidopsis genes encoding functional DHNA-CoA thioesterases. The deduced plant proteins display low percentages of identity with cyanobacterial DHNA-CoA thioesterases, and do not even share the same catalytic motif. GFP-fusion experiments demonstrated that the Arabidopsis proteins are targeted to peroxisomes, and subcellular fractionations of Arabidopsis leaves confirmed that DHNA-CoA thioesterase activity occurs in this organelle. In vitro assays with various aromatic and aliphatic acyl-CoA thioester substrates showed that the recombinant Arabidopsis enzymes preferentially hydrolyze DHNA-CoA. Cognate T-DNA knock-down lines display reduced DHNA-CoA thioesterase activity and phylloquinone content, establishing in vivo evidence that the Arabidopsis enzymes are involved in phylloquinone biosynthesis. Extraordinarily, structure-based phylogenies coupled to comparative genomics demonstrate that plant DHNA-CoA thioesterases originate from a horizontal gene transfer with a bacterial species of the Lactobacillales order. © 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd.

Ethanol from hydrolyzed whey permeate using Saccharomyces cerevisiae in a membrane recycle bioreactor

Energy Technology Data Exchange (ETDEWEB)

Mehaia, M A [King Saud Univ., Buriedah (Saudi Arabia). Dairy Technology Lab.; Cheryan, M [Illinois Univ., Urbana, IL (USA). Agricultural Bioprocess Lab.

1990-02-13

A diauxic fermentation was observed during batch fermentation of enzyme-hydrolyzed whey permeate to ethanol by Saccharomyces cerevisiae. Glucose was consumed before and much faster than galactose. In the continuous membrane recycle bioreactor (MRB), sugar utilization was a function of dilution rate and concentration of sugars. At a cell concentration of 160 kg/m{sup 3}, optimum productivity was 31 kg/(m{sup 3}.h) at ethanol concentration of 65 kg/m{sup 3}. Low levels of acetate (0.05-0.1 M) reduced cell growth during continuous fermentation, but also reduced galactose utilization. (orig.).

Polyvinylpyrrolidone-Capped Silver Nanoparticle Inhibits Infection of Carbapenem-Resistant Strain of Acinetobacter baumannii in the Human Pulmonary Epithelial Cell

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Vishvanath Tiwari

2017-08-01

Full Text Available Acinetobacter baumannii, an opportunistic ESKAPE pathogen, causes respiratory and urinary tract infections. Its prevalence increases gradually in the clinical setup. Pathogenicity of Acinetobacter is significantly influenced by its ability to infect and survive in human pulmonary cells. Therefore, it is important to study the infection of A. baumannii in human pulmonary host cell (A-549, monitoring surface interacting and internalized bacteria. It was found that during infection of A. baumannii, about 40% bacteria adhered to A-549, whereas 20% got internalized inside pulmonary cell and induces threefold increase in the reactive oxygen species production. We have synthesized polyvinylpyrrolidone (PVP-capped AgNPs using chemical methods and tested its efficacy against carbapenem-resistant strain of A. baumannii. PVP-capped silver nanoparticles (PVP-AgNPs (30 µM have shown antibacterial activity against carbapenem-resistant strain of A. baumannii and this concentration does not have any cytotoxic effect on the human pulmonary cell line (IC50 is 130 µM. Similarly, PVP-AgNPs treatment decreases 80% viability of intracellular bacteria, decreases adherence of A. baumannii to A-549 (40 to 2.2%, and decreases intracellular concentration (20 to 1.3% of A. baumannii. This concludes that PVP-AgNPs can be developed as a substitute for carbapenem to control the infection caused by carbapenem-resistant A. baumannii.

Excess Mortality Associated With Colistin-Tigecycline Compared With Colistin-Carbapenem Combination Therapy for Extensively Drug-Resistant Acinetobacter baumannii Bacteremia: A Multicenter Prospective Observational Study.

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Cheng, Aristine; Chuang, Yu-Chung; Sun, Hsin-Yun; Sheng, Wang-Huei; Yang, Chia-Jui; Liao, Chun-Hsing; Hsueh, Po-Ren; Yang, Jia-Ling; Shen, Ni-Jiin; Wang, Jann-Tay; Hung, Chien-Ching; Chen, Yee-Chun; Chang, Shan-Chwen

2015-06-01

Since few therapeutic options exist for extensively drug resistant Acinetobacter baumannii, an emerging threat in ICUs worldwide, and comparative prospective studies of colistin-based combination therapies are lacking, our objective was to compare the outcomes of patients with extensively drug-resistant A. baumannii bacteremia, treated with colistin-carbapenem and colistin-tigecycline combinations. Prospective, observational, multicenter study. Adults with extensively drug-resistant A. baumannii bacteremia were prospectively followed from 2010 to 2013 at three hospitals in Taiwan. Extensively drug-resistant A. baumannii was defined as A. baumannii (genospecies 2) nonsusceptible to all drug classes except for colistin and tigecycline, and standard combination therapy as use of parenteral colistin-carbapenem or colistin-tigecycline for at least 48 hours after onset of bacteremia. Primary outcome measure was 14-day mortality. Of the 176 episodes of extensively drug-resistant A. baumannii bacteremia evaluated, 55 patients with a median (interquartile range) age of 62 years (44-79 yr) and Sequential Organ Failure Assessment score of 9 (5-13) points received standard combination therapy: colistin-tigecycline in 29 patients and colistin-carbapenem in 26. Crude 14-day and in-hospital mortality rates for patients receiving colistin-tigecycline versus patients receiving colistin-carbapenem were 35% versus 15% (p=0.105) and 69% versus 50% (p=0.152), respectively. Breakthrough extensively drug-resistant A. baumannii bacteremia under steady state concentrations of combination therapy for colistin-tigecycline group was 18% and for colistin-carbapenem group was 0% (p=0.059). Eleven patients (20.0%) developed nephrotoxicity. After adjusting for age, sex, comorbidity, initial disease severity, loading colistin dose, polymicrobial infection, and primary infection site, excess 14-day mortality was associated with the use of colistin-tigecycline in the subgroup with tigecycline

Hydrolyzed infant formula and early β-cell autoimmunity

DEFF Research Database (Denmark)

Knip, Mikael; Åkerblom, Hans K; Becker, Dorothy

2014-01-01

-associated autoantibodies out of 4 analyzed. Autoantibodies to insulin, glutamic acid decarboxylase, and the insulinoma-associated-2 (IA-2) molecule were analyzed using radiobinding assays and islet cell antibodies with immunofluorescence during a median observation period of 7.0 years (mean, 6.3 years). RESULTS......IMPORTANCE: The disease process leading to clinical type 1 diabetes often starts during the first years of life. Early exposure to complex dietary proteins may increase the risk of β-cell autoimmunity in children at genetic risk for type 1 diabetes. Extensively hydrolyzed formulas do not contain...... intact proteins. OBJECTIVE: To test the hypothesis that weaning to an extensively hydrolyzed formula decreases the cumulative incidence of diabetes-associated autoantibodies in young children. DESIGN, SETTING, AND PARTICIPANTS: A double-blind randomized clinical trial of 2159 infants with HLA...

Molecular cloning and characterization of a novel pyrethroid-hydrolyzing esterase originating from the Metagenome

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Liu Yu

2008-12-01

, purified and characterized. The molecular mass of the native enzyme was approximately 31 kDa as determined by gel filtration. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the deduced amino acid sequence of the Pye3 indicated molecular mass of 31 kDa and 31.5 kDa, respectively, suggesting that the Pye3 is a monomer. The purified Pye3 not only degraded all pyrethroid pesticides tested, but also hydrolyzed ρ-nitrophenyl esters of medium-short chain fatty acids, indicating that the Pye3 is an esterase with broader specificity. The Km values for trans-Permethrin and cis-permethrin are 0.10 μM and 0.18 μM, respectively, and these catalytic properties were superior to carboxylesterases from resistant insects and mammals. The catalytic activity of the Pye3 was strongly inhibited by Hg2+, Ag+, ρ-chloromercuribenzoate, whereas less pronounced effect was observed in the presence of divalent cations, the chelating agent EDTA and phenanthroline. Conclusion A novel pyrethroid-hydrolyzing esterase gene was successfully cloned using metagenomic DNA combined with activity-based functional screening from soil, the broader substrate specificities and higher activity of the pyrethroid-hydrolyzing esterase (Pye3 make it an ideal candidate for in situ for detoxification of pyrethroids where they cause environmental contamination problems. Consequently, metagenomic DNA clone library offers possibilities to discover novel bio-molecules through the expression of genes from uncultivated bacteria.

The Hospital Water Environment as a Reservoir for Carbapenem-Resistant Organisms Causing Hospital-Acquired Infections-A Systematic Review of the Literature.

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Kizny Gordon, Alice E; Mathers, Amy J; Cheong, Elaine Y L; Gottlieb, Thomas; Kotay, Shireen; Walker, A Sarah; Peto, Timothy E A; Crook, Derrick W; Stoesser, Nicole

2017-05-15

Over the last 20 years there have been 32 reports of carbapenem-resistant organisms in the hospital water environment, with half of these occurring since 2010. The majority of these reports have described associated clinical outbreaks in the intensive care setting, affecting the critically ill and the immunocompromised. Drains, sinks, and faucets were most frequently colonized, and Pseudomonas aeruginosa the predominant organism. Imipenemase (IMP), Klebsiella pneumoniae carbapenemase (KPC), and Verona integron-encoded metallo-β-lactamase (VIM) were the most common carbapenemases found. Molecular typing was performed in almost all studies, with pulse field gel electrophoresis being most commonly used. Seventy-two percent of studies reported controlling outbreaks, of which just more than one-third eliminated the organism from the water environment. A combination of interventions seems to be most successful, including reinforcement of general infection control measures, alongside chemical disinfection. The most appropriate disinfection method remains unclear, however, and it is likely that replacement of colonized water reservoirs may be required for long-term clearance. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

Incidence of carbapenem resistant nonfermenting gram negative bacilli from patients with respiratory infections in the intensive care units

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Gladstone P

2005-01-01

Full Text Available Resistance to carbapenems is commonly seen in nonfermenting gram negative bacilli (NFGNB. We document herein the prevalence of carbapenem resistance in NFGNB isolated from patients with respiratory tract infections in the intensive care units (ICUs. A total of 460 NFGNB were isolated from 606 endotracheal aspirate specimens during January through December 2003, of which 56 (12.2% were found to be resistant to imipenem and meropenem. Of these, 24 (42.8% were Pseudomonas aeruginosa , 8 (14.2% were Acinetobacter spp. and 24 (42.8% were other NFGNB. Stringent protocols such as antibiotic policies and resistance surveillance programs are mandatory to curb these bacteria in ICU settings.

Overexpression of an Outer Membrane Protein Associated with Decreased Susceptibility to Carbapenems in Proteus mirabilis

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Tsai, Yi-Lin; Wang, Min-Cheng; Hsueh, Po-Ren; Liu, Ming-Che; Hu, Rouh-Mei; Wu, Yue-Jin; Liaw, Shwu-Jen

2015-01-01

Proteus mirabilis isolates commonly have decreased susceptibility to imipenem. Previously, we found P. mirabilis hfq mutant was more resistant to imipenem and an outer membrane protein (OMP) could be involved. Therefore, we investigated the role of this OMP in carbapenem susceptibility. By SDS-PAGE we found this OMP (named ImpR) was increased in hfq mutant and LC-MS/MS revealed it to be the homologue of Salmonella YbfM, which is a porin for chitobiose and subject to MicM (a small RNA) regulation. We demonstrated that ImpR overexpression resulted in increased carbapenem MICs in the laboratory strain and clinical isolates. Chitobiose induced expression of chb (a chitobiose utilization operon). Real-time RT-PCR and SDS-PAGE were performed to elucidate the relationship of hfq, impR, chb and MicM in P. mirabilis. We found MicM RNA was decreased in hfq mutant and chbBC-intergenic region (chbBC-IGR) overexpression strain (chbIGRov), while impR mRNA was increased in hfq mutant, micM mutant and chbIGRov strain. In addition, mutation of hfq or micM and overexpression of chbBC-IGR increased ImpR protein level. Accordingly, chitobiose made wild-type have higher levels of ImpR protein and are more resistant to carbapenems. Hfq- and MicM-complemented strains restored wild-type MICs. Mutation of both impR and hfq eliminated the increase in carbapenem MICs observed in hfq mutant and ImpR-complementation of hfq/impR double mutant resulted in MICs as hfq mutant, indicating that the ImpR-dependent decreased carbapenem susceptibility of hfq mutant. These indicate MicM was antisense to impR mRNA and was negatively-regulated by chbBC-IGR. Together, overexpression of ImpR contributed to the decreased carbapenem susceptibility in P. mirabilis. PMID:25756370

Risk factors for and role of OprD protein in increasing minimal inhibitory concentrations of carbapenems in clinical isolates of Pseudomonas aeruginosa.

Science.gov (United States)

Hirabayashi, Aki; Kato, Daizo; Tomita, Yuka; Iguchi, Mitsutaka; Yamada, Keiko; Kouyama, Yuichi; Morioka, Hiroshi; Tetsuka, Nobuyuki; Yagi, Tetsuya

2017-11-01

This study examined the risk factors for, and molecular mechanisms underlying, the increase in carbapenem minimum inhibitory concentrations (MICs) in clinical isolates of Pseudomonas aeruginosa. Consecutive clinical isolates of P. aeruginosa were collected. The MicroScan WalkAway system detected more than fourfold increases in the MICs of carbapenems in P. aeruginosa isolates serially recovered from some patients during their clinical course. The clinical risk factors associated with this increase were examined by multiple logistic regression analysis. Western blot analysis and nucleotide sequencing of the oprD gene of 19 clonally related and paired P. aeruginosa isolates from the same patients were undertaken to examine the mechanisms underlying the increase in MICs. The results showed that prior use of carbapenems (OR, 2.799; 95 % CI, 1.088-7.200; P=0.033) and the use of ventilators or tracheostomies (OR, 2.648; 95 % CI, 1.051-6.671; P=0.039) were risk factors for increased carbapenem MICs. Analysis of the underlying mechanisms revealed that loss of functional OprD protein due to mutation of the oprD gene tended to occur in P. aeruginosa isolates with imipenem MICs of more than 8 µg ml -1 ; a reduction in OprD expression was observed in P. aeruginosa isolates with imipenem MICs of 4 or 8 µg ml -1 . This difference in the resistance mechanism was not correlated with the MICs of meropenem. This difference in the resistance mechanism of P. aeruginosa indicates a critical breakpoint at an imipenem MIC of 8 µg ml -1 , in accordance with EUCAST criteria. Reducing carbapenem use will prevent P. aeruginosa clinical isolates from developing resistance to carbapenems.

Dissemination of carbapenem-resistant Acinetobacter baumannii in patients with burn injuries.

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Shoja, Saeed; Moosavian, Mojtaba; Rostami, Soodabeh; Farahani, Abbas; Peymani, Amir; Ahmadi, Khadijeh; Ebrahimifard, Nasim

2017-04-01

Carbapenem-resistant Acinetobacter baumannii has emerged as an important cause of infection in burn patients. This study aimed to characterize the antimicrobial susceptibility pattern, determine the prevalence of oxacillinase and metallo-beta-lactamase (MBL) genes, and type the A. baumannii isolates obtained from burn patients. During a 1-year period, a total of 40 nonduplicated isolates of A. baumannii were obtained from burn patients who were hospitalized in the Taleghani Burn Hospital in Ahvaz, in the southwest of Iran. Testing for antimicrobial susceptibility was carried out by disk diffusion and E-test. To screen MBL production, a double disk synergy and MBL E-test were performed. The presence of bla OXA-23-like , bla OXA-24-like , bla OXA-51-like and bla OXA-58-like , bla VIM , bla IMP and bla SPM , and bla NDM was sought by polymerase chain reaction (PCR). Repetitive extragenic palindromic sequence-based PCR was carried out for determination of isolates clonality. Overall, 92.5% of isolates were carbapenem-resistant. Polymyxin B, colistin, and ampicillin-sulbactam were the most effective agents in vitro, with a susceptibility rate of 100%, 97.5%, and 72.5%, respectively. According to the double disk synergy and E-test, 55.6% and 97.3% of isolates were MBL producers, respectively. Furthermore, 70% of isolates harbored bla OXA-23-like and 20% were positive for bla OXA-24-like. However, no encoding genes were detected for bla VIM , bla IMP and bla SPM , bla NDM , and bla OXA-58-like . Repetitive extragenic palindromic sequence-based PCR revealed that carbapenem-resistant isolates belonged to four clones, including A, B, C, and D; the predominant clones were B and C. The rate of carbapenem resistance was high, and it appeared that bla OXA-23-like and bla OXA-24-like contributed to the carbapenem resistance of A. baumannii isolates. This result suggests that the two predominant clones of A. baumannii were spread among burn patients. In order to prevent future

Functional analyses of multiple lichenin-degrading enzymes from the rumen bacterium Ruminococcus albus 8.

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Iakiviak, Michael; Mackie, Roderick I; Cann, Isaac K O

2011-11-01

Ruminococcus albus 8 is a fibrolytic ruminal bacterium capable of utilization of various plant cell wall polysaccharides. A bioinformatic analysis of a partial genome sequence of R. albus revealed several putative enzymes likely to hydrolyze glucans, including lichenin, a mixed-linkage polysaccharide of glucose linked together in β-1,3 and β-1,4 glycosidic bonds. In the present study, we demonstrate the capacity of four glycoside hydrolases (GHs), derived from R. albus, to hydrolyze lichenin. Two of the genes encoded GH family 5 enzymes (Ra0453 and Ra2830), one gene encoded a GH family 16 enzyme (Ra0505), and the last gene encoded a GH family 3 enzyme (Ra1595). Each gene was expressed in Escherichia coli, and the recombinant protein was purified to near homogeneity. Upon screening on a wide range of substrates, Ra0453, Ra2830, and Ra0505 displayed different hydrolytic properties, as they released unique product profiles. The Ra1595 protein, predicted to function as a β-glucosidase, preferred cleavage of a nonreducing end glucose when linked by a β-1,3 glycosidic bond to the next glucose residue. The major product of Ra0505 hydrolysis of lichenin was predicted to be a glucotriose that was degraded only by Ra0453 to glucose and cellobiose. Most importantly, the four enzymes functioned synergistically to hydrolyze lichenin to glucose, cellobiose, and cellotriose. This lichenin-degrading enzyme mix should be of utility as an additive to feeds administered to monogastric animals, especially those high in fiber.

Enzymes in Fermented Fish.

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Giyatmi; Irianto, H E

Fermented fish products are very popular particularly in Southeast Asian countries. These products have unique characteristics, especially in terms of aroma, flavor, and texture developing during fermentation process. Proteolytic enzymes have a main role in hydrolyzing protein into simpler compounds. Fermentation process of fish relies both on naturally occurring enzymes (in the muscle or the intestinal tract) as well as bacteria. Fermented fish products processed using the whole fish show a different characteristic compared to those prepared from headed and gutted fish. Endogenous enzymes like trypsin, chymotrypsin, elastase, and aminopeptidase are the most involved in the fermentation process. Muscle tissue enzymes like cathepsins, peptidases, transaminases, amidases, amino acid decarboxylases, glutamic dehydrogenases, and related enzymes may also play a role in fish fermentation. Due to the decreased bacterial number during fermentation, contribution of microbial enzymes to proteolysis may be expected prior to salting of fish. Commercial enzymes are supplemented during processing for specific purposes, such as quality improvement and process acceleration. In the case of fish sauce, efforts to accelerate fermentation process and to improve product quality have been studied by addition of enzymes such as papain, bromelain, trypsin, pepsin, and chymotrypsin. © 2017 Elsevier Inc. All rights reserved.

CARBAPENEM-RESISTANT ACINETOBACTER BAUMANII POSTOPERATIVE MENINGITIS

OpenAIRE

Laura Ghibu; Egidia Miftode; Olivia Dorneanu; Carmen Dorobat

2011-01-01

Acinetobacter baumannii is an opportunistic pathogen of increasing relevance in hospital infections during the last 15 years.This organism causes a wide range of infection .Extensive use of antibiotics within hospitals has contribute to the emergence of multidrug-resistent A.baumannii strains that exhibit resistance to a wide range of antibiotics ,including carbapenems.We report the case of an 37 years old man diagnosed with Acinetobacter multidrug-resistant post-neurosurgical meningitis with...

Carbapenem-resistant and cephalosporin-susceptible: a worrisome phenotype among Pseudomonas aeruginosa clinical isolates in Brazil.

Science.gov (United States)

Campana, Eloiza Helena; Xavier, Danilo Elias; Petrolini, Fernanda Villas-Boas; Cordeiro-Moura, Jhonatha Rodrigo; Araujo, Maria Rita Elmor de; Gales, Ana Cristina

The mechanisms involved in the uncommon resistance phenotype, carbapenem resistance and broad-spectrum cephalosporin susceptibility, were investigated in 25 Pseudomonas aeruginosa clinical isolates that exhibited this phenotype, which were recovered from three different hospitals located in São Paulo, Brazil. The antimicrobial susceptibility profile was determined by CLSI broth microdilution. β-lactamase-encoding genes were investigated by PCR followed by DNA sequencing. Carbapenem hydrolysis activity was investigated by spectrophotometer and MALDI-TOF assays. The mRNA transcription level of oprD was assessed by qRT-PCR and the outer membrane proteins profile was evaluated by SDS-PAGE. Genetic relationship among P. aeruginosa isolates was assessed by PFGE. Carbapenems hydrolysis was not detected by carbapenemase assay in the carbapenem-resistant and cephalosporin-susceptible P. aueruginosa clinical isolates. OprD decreased expression was observed in all P. aeruginosa isolates by qRT-PCR. The outer membrane protein profile by SDS-PAGE suggested a change in the expression of the 46kDa porin that could correspond to OprD porin. The isolates were clustered into 17 genotypes without predominance of a specific PFGE pattern. These results emphasize the involvement of multiple chromosomal mechanisms in carbapenem-resistance among clinical isolates of P. aeruginosa, alert for adaptation of P. aeruginosa clinical isolates under antimicrobial selective pressure and make aware of the emergence of an uncommon phenotype among P. aeruginosa clinical isolates. Copyright © 2016 Sociedade Brasileira de Infectologia. Published by Elsevier Editora Ltda. All rights reserved.

Susceptibilities to carbapenems and presence of cphA gene on food-borne Aeromonas

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Bibiana María Martín Talavera

2006-07-01

Full Text Available The purpose of this study was to determine the susceptibilities of food-borne Aeromonas to carbapenems, as well as to investigate the presence of a metallo carbapenemase-encoding gene, named cphA. Minimum Inhibitory Concentration (MIC was determined following NCCLS standards. All the tested microorganisms were susceptible to imipenem, meropenem and biapenem. However, a strong inoculum size effect on carbapenem MICs was observed for most of the strains. Six strains, out of seven, showed the presence of metallo--beta-lactamases but cphA gene was detected in only two strains of A. veronii bv. sobria.O objetivo deste estudo foi determinar a suscetibilidade de aeromonas de origem alimentar a carbapenems bem como investigar a presença de um gene codificante de metalocarbapenemase, denominado "cph A". A suscetibilidade in vitro foi determinada pelo metodo de diluição em agar. Todas as cepas foram suscetíveis a Imipenem, Meropenem e Biapenem. Porém foi observado um forte efeito de tamanho do inóculo sobre as CIM das carbapenems na maioria das cepas. A detecção de metalo-beta-lactamase foi realizada pelo metodo lodometrico. Seis cepas das sete testadas demostraron a presença da enzima. A presença do gene cphA foi determinada por PCR e foi detectada em duas cepas de A veronii bv. sobria.

Angiotensin I-Converting Enzyme (ACE Inhibitory Activity and ACE Inhibitory Peptides of Salmon (Salmo salar Protein Hydrolysates Obtained by Human and Porcine Gastrointestinal Enzymes

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Małgorzata Darewicz

2014-08-01

Full Text Available The objectives of the present study were two-fold: first, to detect whether salmon protein fractions possess angiotensin I-converting enzyme (ACE inhibitory properties and whether salmon proteins can release ACE inhibitory peptides during a sequential in vitro hydrolysis (with commercial porcine enzymes and ex vivo digestion (with human gastrointestinal enzymes. Secondly, to evaluate the ACE inhibitory activity of generated hydrolysates. A two-step ex vivo and in vitro model digestion was performed to simulate the human digestion process. Salmon proteins were degraded more efficiently by porcine enzymes than by human gastrointestinal juices and sarcoplasmic proteins were digested/hydrolyzed more easily than myofibrillar proteins. The ex vivo digested myofibrillar and sarcoplasmic duodenal samples showed IC50 values (concentration required to decrease the ACE activity by 50% of 1.06 and 2.16 mg/mL, respectively. The in vitro hydrolyzed myofibrillar and sarcoplasmic samples showed IC50 values of 0.91 and 1.04 mg/mL, respectively. Based on the results of in silico studies, it was possible to identify 9 peptides of the ex vivo hydrolysates and 7 peptides of the in vitro hydrolysates of salmon proteins of 11 selected peptides. In both types of salmon hydrolysates, ACE-inhibitory peptides IW, IY, TVY and VW were identified. In the in vitro salmon protein hydrolysates an ACE-inhibitory peptides VPW and VY were also detected, while ACE-inhibitory peptides ALPHA, IVY and IWHHT were identified in the hydrolysates generated with ex vivo digestion. In our studies, we documented ACE inhibitory in vitro effects of salmon protein hydrolysates obtained by human and as well as porcine gastrointestinal enzymes.

Impact of carbapenem resistance on the outcome of patients' hospital-acquired bacteraemia caused by Klebsiella pneumoniae.

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Hussein, K; Raz-Pasteur, A; Finkelstein, R; Neuberger, A; Shachor-Meyouhas, Y; Oren, I; Kassis, I

2013-04-01

Carbapenem-resistant Enterobacteriaceae, especially Klebsiella spp., have become a major health problem recently worldwide. Since 2006 the incidence of carbapenem-resistant Klebsiella pneumoniae (CRKP) infections has increased substantially in Israel. Bloodstream infections (BSIs) caused by these strains have been associated with high rates of treatment failure and mortality. This study was designed to identify risk factors for carbapenem resistance among patients with healthcare-related (HCR) K. pneumoniae bacteraemia and predictors of mortality associated with HCR-CRKP bacteraemia compared with carbapenem-susceptible K. pneumoniae (CSKP). In this retrospective case-control study, all cases of K. pneumoniae bacteraemia during 2006-2008 were identified. Resistance patterns, underlying morbidities, risk factors for drug resistance and mortality rates were compared for patients with CRKP and CSKP bacteraemia. Two hundred and fourteen patients with CSKP bacteraemia were compared with 103 patients with CRKP bacteraemia. Severe, chronic comorbidities and prior antibiotic use were more frequent among patients with CRKP bacteraemia. On multivariate analysis prior use of macrolides and antibiotic exposure for ≥14 days remained the only independent factors associated with CRKP bacteraemia. Mortality rates of CRKP patients were significantly higher than those of CSKP patients. On multivariate analyses: bedridden status, chronic liver disease, Charlson comorbidity index ≥5, mechanical ventilation, and haemodialysis remained independently associated with mortality among patients with K. pneumoniae bacteraemia. Carbapenem resistance was not a risk factor for mortality. Previous antibiotic exposure is a risk factor for CRKP-BSI. Mortality among patients with K. pneumoniae bacteraemia is associated with serious comorbidities, but not with carbapenem resistance. Copyright © 2012 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

NO EVIDENCE FOR A DARK MATTER DISK WITHIN 4 kpc FROM THE GALACTIC PLANE

International Nuclear Information System (INIS)

Moni Bidin, C.; Carraro, G.; Mendez, R. A.; Van Altena, W. F.

2010-01-01

We estimated the dynamical surface mass density (Σ) at the solar Galactocentric distance between 2 and 4 kpc from the Galactic plane, as inferred from the observed kinematics of the thick disk. We find Σ(z = 2 kpc) = 57.6 ± 5.8 M sun pc -2 , and it shows only a tiny increase in the z range considered by our investigation. We compared our results with the expectations for the visible mass, adopting the most recent estimates in the literature for contributions of the Galactic stellar disk and interstellar medium, and proposed models of the dark matter distribution. Our results match the expectation for the visible mass alone, never differing from it by more than 0.8 M sun pc -2 at any z, and thus we find little evidence for any dark component. We assume that the dark halo could be undetectable with our method, but the dark disk, recently proposed as a natural expectation of the ΛCDM models, should be detected. Given the good agreement with the visible mass alone, models including a dark disk are less likely, but within errors its existence cannot be excluded. In any case, these results put constraints on its properties: thinner models (scale height lower than 4 kpc) reconcile better with our results and, for any scale height, the lower-density models are preferred. We believe that successfully predicting the stellar thick disk properties and a dark disk in agreement with our observations could be a challenging theoretical task.

Quantitative Structure-Activity Relationship Modeling Coupled with Molecular Docking Analysis in Screening of Angiotensin I-Converting Enzyme Inhibitory Peptides from Qula Casein Hydrolysates Obtained by Two-Enzyme Combination Hydrolysis.

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Lin, Kai; Zhang, Lanwei; Han, Xue; Meng, Zhaoxu; Zhang, Jianming; Wu, Yifan; Cheng, Dayou

2018-03-28

In this study, Qula casein derived from yak milk casein was hydrolyzed using a two-enzyme combination approach, and high angiotensin I-converting enzyme (ACE) inhibitory activity peptides were screened by quantitative structure-activity relationship (QSAR) modeling integrated with molecular docking analysis. Hydrolysates (casein presents an excellent source to produce ACE inhibitory peptides.

Antibacterial activity of exogenous glutathione and its synergism on antibiotics sensitize carbapenem-associated multidrug resistant clinical isolates of Acinetobacter baumannii.

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Alharbe, Roaa; Almansour, Ayidh; Kwon, Dong H

2017-10-01

A major clinical impact of A. baumannii is hospital-acquired infections including ventilator-associated pneumonia. The treatment of this pathogen is often difficult due to its innate and acquired resistance to almost all commercially available antibiotics. Infections with carbapenem-associated multidrug resistant A. baumannii is the most problematic. Glutathione is a tripeptide thiol-antioxidant and antibacterial activity of exogenous glutathione was reported in some bacteria. However, clinical relevance and molecular details of the antibacterial activity of glutathione are currently unclear. Seventy clinical isolates of A. baumannii including 63 carbapenem-associated multidrug resistant isolates and a type strain A. baumannii ATCC 19606 were used to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Fractional inhibitory concentration (FIC) and time-killing activity with meropenem and/or glutathione were also determined in the carbapenem-associated multidrug resistant isolates. In addition, the roles of exogenous glutathione in multidrug efflux pumps and β-lactamase production were examined. Levels of MIC and MBC were ranged from 10 to 15mM of exogenous glutathione. All tested carbapenem-associated multidrug resistant isolates were sensitized by all tested antibiotics in combination with subinhibitory concentrations of glutathione. FIC levels of glutathione with carbapenem (meropenem) were allcarbapenem-associated multidrug resistant isolates were killed by subinhibitory concentrations of both glutathione and meropenem at>2log10 within 12h, suggesting glutathione synergistically interacts with meropenem. The roles of multidrug efflux pumps and β-lactamase production were excluded for the glutathione-mediated antibiotic susceptibility. Overall results demonstrate that the antibacterial activity of glutathione is clinically relevant and its synergism on antibiotics sensitizes clinical isolates of A. baumannii regardless

Treatment of ESBL-producing Klebsiella pneumoniae bacteraemia with carbapenems or flomoxef: a retrospective study and laboratory analysis of the isolates.

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Lee, Chen-Hsiang; Su, Lin-Hui; Tang, Ya-Fen; Liu, Jien-Wei

2006-11-01

To better understand the clinical outcomes of patients with extended-spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBL-KP) bacteraemia treated with either flomoxef or a carbapenem, and to evaluate the in vitro activities of these antibiotics against ESBL-KP. Retrospective analyses to identify risk factors for mortality in patients with flomoxef-susceptible ESBL-KP, especially addressing the therapeutic roles of flomoxef and carbapenem. In vitro activities of flomoxef and carbapenem against flomoxef-susceptible ESBL-KP isolates were evaluated by susceptibility testing and time-kill study. Twenty-seven patients (flomoxef group, n=7; carbapenem group, n=20) were included. Clinical severity reflected by high Pitt bacteraemia score (>or=6) was an independent risk factor for mortality (OR 13.43; 95% CI, 1.08-166.73; P=0.043), while use of flomoxef or a carbapenem was not. The MICs of flomoxef and carbapenem indicated that the tested ESBL-KP were susceptible to these antibiotics regardless of the inoculum size of 10(5) or 10(7) cfu/mL. Time-kill study showed that these antibiotics (flomoxef 8 mg/L and meropenem 4 mg/L) each acted actively against and inhibited the regrowth of the tested ESBL-KP for at least 24 h. Flomoxef might be as clinically effective as a carbapenem in treating flomoxef-susceptible ESBL-KP bacteraemia.

The Fornax Cluster VLT Spectroscopic Survey II - Planetary Nebulae kinematics within 200 kpc of the cluster core

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Spiniello, C.; Napolitano, N. R.; Arnaboldi, M.; Tortora, C.; Coccato, L.; Capaccioli, M.; Gerhard, O.; Iodice, E.; Spavone, M.; Cantiello, M.; Peletier, R.; Paolillo, M.; Schipani, P.

2018-06-01

We present the largest and most spatially extended planetary nebulae (PNe) catalogue ever obtained for the Fornax cluster. We measured velocities of 1452 PNe out to 200 kpc in the cluster core using a counter-dispersed slitless spectroscopic technique with data from FORS2 on the Very Large Telescope (VLT). With such an extended spatial coverage, we can study separately the stellar haloes of some of the cluster main galaxies and the intracluster light. In this second paper of the Fornax Cluster VLT Spectroscopic Survey, we identify and classify the emission-line sources, describe the method to select PNe, and calculate their coordinates and velocities from the dispersed slitless images. From the PN 2D velocity map, we identify stellar streams that are possibly tracing the gravitational interaction of NGC 1399 with NGC 1404 and NGC 1387. We also present the velocity dispersion profile out to ˜200 kpc radii, which shows signatures of a superposition of the bright central galaxy and the cluster potential, with the latter clearly dominating the regions outside R ˜ 1000 arcsec (˜100 kpc).

Emergence of Pseudomonas aeruginosa with KPC-type carbapenemase in a teaching hospital: an 8-year study.

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García Ramírez, Dolores; Nicola, Federico; Zarate, Soledad; Relloso, Silvia; Smayevsky, Jorgelina; Arduino, Sonia

2013-10-01

An outbreak of Klebsiella pneumoniae carbapenamase (KPC)-producing K. pneumoniae occurred at our institution. Multiresistant Pseudomonas aeruginosa could have acquired this transmissible resistance mechanism, going unnoticed because its phenotypic detection in this species is difficult. We compared P. aeruginosa isolates obtained before and after the KPC-producing K. pneumoniae outbreak. No bla(KPC) genes were detected in the isolates obtained before the outbreak, whereas 33/76 (43%) of the isolates obtained after the outbreak harboured the bla(KPC) gene. P. aeruginosa may thus become a reservoir of this transmissible resistance mechanism. It is very important to understand the epidemiology of these multiresistant isolates, in order to achieve early implementation of adequate control measures to contain and reduce their dissemination in the hospital environment.

Structural Studies of Bacterial Enzymes and their Relation to Antibiotic Resistance Mechanisms - Final Paper

Energy Technology Data Exchange (ETDEWEB)

Maltz, Lauren [SLAC National Accelerator Lab., Menlo Park, CA (United States)

2015-08-27

By using protein crystallography and X-ray diffraction, structures of bacterial enzymes were solved to gain a better understanding of how enzymatic modification acts as an antibacterial resistance mechanism. Aminoglycoside phosphotransferases (APHs) are one of three aminoglycoside modifying enzymes that confer resistance to the aminoglycoside antibiotics via enzymatic modification, rendering many drugs obsolete. Specifically, the APH(2”) family vary in their substrate specificities and also in their preference for the phosphate donor (ADP versus GDP). By solving the structures of members of the APH(2”) family of enzymes, we can see how domain movements are important to their substrate specificity. Our structure of the ternary complex of APH(2”)-IIIa with GDP and kanamycin, when compared to the known structures of APH(2”)-IVa, reveals that there are real physical differences between these two enzymes, a structural finding that explains why the two enzymes differ in their preferences for certain aminoglycosides. Another important group of bacterial resistance enzymes are the Class D β- lactamases. Oxacillinase carbapenemases (OXAs) are part of this enzyme class and have begun to confer resistance to ‘last resort’ drugs, most notably carbapenems. Our structure of OXA-143 shows that the conformational flexibility of a conserved hydrophobic residue in the active site (Val130) serves to control the entry of a transient water molecule responsible for a key step in the enzyme’s mechanism. Our results provide insight into the structural mechanisms of these two different enzymes

THE MILKY WAY'S CIRCULAR-VELOCITY CURVE BETWEEN 4 AND 14 kpc FROM APOGEE DATA

Energy Technology Data Exchange (ETDEWEB)

Bovy, Jo [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States); Allende Prieto, Carlos; Meszaros, Szabolcs [Instituto de Astrofisica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain); Beers, Timothy C. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Bizyaev, Dmitry; Ebelke, Garrett L.; Malanushenko, Elena; Malanushenko, Viktor [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349 (United States); Da Costa, Luiz N.; Girardi, Leo; Maia, Marcio A. G. [Laboratorio Interinstitucional de e-Astronomia-LIneA, Rua Gal. Jose Cristino 77, Rio de Janeiro, RJ 20921-400 (Brazil); Cunha, Katia [Observatorio Nacional, Rio de Janeiro, RJ 20921-400 (Brazil); Eisenstein, Daniel J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., MS 20, Cambridge, MA 02138 (United States); Frinchaboy, Peter M. [Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX 76129 (United States); Garcia Perez, Ana Elia; Hearty, Fred R.; Majewski, Steven R.; Nidever, David L. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States); Hogg, David W. [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Holtzman, Jon, E-mail: bovy@ias.edu [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States); and others

2012-11-10

We measure the Milky Way's rotation curve over the Galactocentric range 4 kpc {approx}< R {approx}< 14 kpc from the first year of data from the Apache Point Observatory Galactic Evolution Experiment. We model the line-of-sight velocities of 3365 stars in 14 fields with b = 0 Degree-Sign between 30 Degree-Sign {<=} l {<=} 210 Degree-Sign out to distances of 10 kpc using an axisymmetric kinematical model that includes a correction for the asymmetric drift of the warm tracer population ({sigma} {sub R} Almost-Equal-To 35 km s{sup -1}). We determine the local value of the circular velocity to be V{sub c} (R {sub 0}) = 218 {+-} 6 km s{sup -1} and find that the rotation curve is approximately flat with a local derivative between -3.0 km s{sup -1} kpc{sup -1} and 0.4 km s{sup -1} kpc{sup -1}. We also measure the Sun's position and velocity in the Galactocentric rest frame, finding the distance to the Galactic center to be 8 kpc < R {sub 0} < 9 kpc, radial velocity V {sub R, Sun} = -10 {+-} 1 km s{sup -1}, and rotational velocity V {sub {phi}, Sun} = 242{sup +10} {sub -3} km s{sup -1}, in good agreement with local measurements of the Sun's radial velocity and with the observed proper motion of Sgr A*. We investigate various systematic uncertainties and find that these are limited to offsets at the percent level, {approx}2 km s{sup -1} in V{sub c} . Marginalizing over all the systematics that we consider, we find that V{sub c} (R {sub 0}) < 235 km s{sup -1} at >99 % confidence. We find an offset between the Sun's rotational velocity and the local circular velocity of 26 {+-} 3 km s{sup -1}, which is larger than the locally measured solar motion of 12 km s{sup -1}. This larger offset reconciles our value for V{sub c} with recent claims that V{sub c} {approx}> 240 km s{sup -1}. Combining our results with other data, we find that the Milky Way's dark-halo mass within the virial radius is {approx}8 Multiplication-Sign 10{sup 11} M {sub Sun }.

The Proprotein Convertase KPC-1/Furin Controls Branching and Self-avoidance of Sensory Dendrites in Caenorhabditis elegans

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Bülow, Hannes E.

2014-01-01

Animals sample their environment through sensory neurons with often elaborately branched endings named dendritic arbors. In a genetic screen for genes involved in the development of the highly arborized somatosensory PVD neuron in C. elegans, we have identified mutations in kpc-1, which encodes the homolog of the proprotein convertase furin. We show that kpc-1/furin is necessary to promote the formation of higher order dendritic branches in PVD and to ensure self-avoidance of sister branches, but is likely not required during maintenance of dendritic arbors. A reporter for kpc-1/furin is expressed in neurons (including PVD) and kpc-1/furin can function cell-autonomously in PVD neurons to control patterning of dendritic arbors. Moreover, we show that kpc-1/furin also regulates the development of other neurons in all major neuronal classes in C. elegans, including aspects of branching and extension of neurites as well as cell positioning. Our data suggest that these developmental functions require proteolytic activity of KPC-1/furin. Recently, the skin-derived MNR-1/menorin and the neural cell adhesion molecule SAX-7/L1CAM have been shown to act as a tripartite complex with the leucine rich transmembrane receptor DMA-1 on PVD mechanosensory to orchestrate the patterning of dendritic branches. Genetic analyses show that kpc-1/furin functions in a pathway with MNR-1/menorin, SAX-7/L1CAM and DMA-1 to control dendritic branch formation and extension of PVD neurons. We propose that KPC-1/furin acts in concert with the ‘menorin’ pathway to control branching and growth of somatosensory dendrites in PVD. PMID:25232734

Comparison of Molecular and Phenotypic Methods for the Detection and Characterization of Carbapenem Resistant Enterobacteriaceae.

Science.gov (United States)

Somily, Ali M; Garaween, Ghada A; Abukhalid, Norah; Absar, Muhammad M; Senok, Abiola C

2016-03-01

In recent years, there has been a rapid dissemination of carbapenem resistant Enterobacteriaceae (CRE). This study aimed to compare phenotypic and molecular methods for detection and characterization of CRE isolates at a large tertiary care hospital in Saudi Arabia. This study was carried out between January 2011 and November 2013 at the King Khalid University Hospital (KKUH) in Saudi Arabia. Determination of presence of extended-spectrum beta-lactamases (ESBL) and carbapenem resistance was in accordance with Clinical and Laboratory Standards Institute (CLSI) guidelines. Phenotypic classification was done by the MASTDISCS(TM) ID inhibitor combination disk method. Genotypic characterization of ESBL and carbapenemase genes was performed by the Check-MDR CT102. Diversilab rep-PCR was used for the determination of clonal relationship. Of the 883 ESBL-positive Enterobacteriaceae detected during the study period, 14 (1.6%) isolates were carbapenem resistant. Both the molecular genotypic characterization and phenotypic testing were in agreement in the detection of all 8 metalo-beta-lactamases (MBL) producing isolates. Of these 8 MBL-producers, 5 were positive for blaNDM gene and 3 were positive for blaVIM gene. Molecular method identified additional blaOXA gene isolates while MASTDISCS(TM) ID detected one AmpC producer isolate. Both methods agreed in identifying 2 carbapenem resistant isolates which were negative for carbapenemase genes. Diversilab rep-PCR analysis of the 9 Klebsiella pneumoniae isolates revealed polyclonal distribution into eight clusters. MASTDISCS(TM) ID is a reliable simple cheap phenotypic method for detection of majority of carbapenemase genes with the exception of the blaOXA gene. We recommend to use such method in the clinical laboratory.

Effect of steam treatment on the hydrolysis of aspen by commerical enzymes

Energy Technology Data Exchange (ETDEWEB)

Macdonald, D G; Mathews, J F

1979-06-01

Steam treatment renders aspen wood more susceptible to hydrolysis by commerical enzyme preparations such as the Onozuka variety. The main products of enzymatic hydrolysis are glucose, xylose, and xylobiose. Cellobiose may have been another product but it could not be measured due to interference by lactose, a sugar found in the enzyme. The hemicellulose fraction of the wood is relatively more rapidly hydrolyzed by the enzymes than the cellulose fraction.

Influence of enzymes on the oil extraction processes in aqueous media

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Ricochon Guillaume

2010-11-01

Full Text Available The methods of oil aqueous extraction process (AEP assisted by enzymes are, over the last 50 years, an alternative designed to replace traditional methods of extraction using organic solvents. To extract the oil using an AEP, the use of specific enzymes, able to hydrolyze some or all components of seeds, can significantly increase the yields of extraction. Hydrolyzing the different constituents of cell walls (cellulose, hemicellulose, pectins, proteins, etc., enzymes are able to enhance the liberation of the oil. A number of physico-chemical parameters must also be considered for the better expression of the enzymatic mixture, while maintaining the quality of oils and meals. This article presents the various factors influencing the release of oil in aqueous media and the main results obtained by this process on various substrates.

Combined use of the modified Hodge test and carbapenemase inhibition test for detection of carbapenemase-producing Enterobacteriaceae and metallo-β-lactamase-producing Pseudomonas spp.

Science.gov (United States)

Song, Wonkeun; Hong, Seong Geun; Yong, Dongeun; Jeong, Seok Hoon; Kim, Hyun Soo; Kim, Han-Sung; Kim, Jae-Seok; Bae, Il Kwon

2015-03-01

We evaluated the combined use of the modified Hodge test (MHT) and carbapenemase inhibition test (CIT) using phenylboronic acid (PBA) and EDTA to detect carbapenemase-producing Enterobacteriaceae (CPE) and metallo-β-lactamase (MBL)-producing Pseudomonas spp. A total of 49 isolates of CPE (15 Klebsiella pneumoniae carbapenemase [KPC], 5 Guiana extended-spectrum β-lactamase [GES]-5, 9 New Delhi metallo-β-lactamase [NDM]-1, 5 Verona integron-encoded metallo-β-lactamase [VIM]-2, 3 imipenem-hydrolyzing β-lactamase [IMP], and 12 oxacillinase [OXA]-48-like), 25 isolates of MBL-producing Pseudomonas spp. (14 VIM-2 and 11 IMP), and 35 carbapenemase-negative controls were included. The MHT was performed for all isolates as recommended by the Clinical and Laboratory Standards Institute. Enhanced growth of the indicator strain was measured in mm with a ruler. The CIT was performed by directly dripping PBA and EDTA solutions onto carbapenem disks that were placed on Mueller-Hinton agar plates seeded with the test strain. Considering the results of the MHT with the ertapenem disk in Enterobacteriaceae and Pseudomonas spp., the CIT with the meropenem disk in Enterobacteriaceae, and the imipenem disk in Pseudomonas spp., three combined disk tests, namely MHT-positive plus PBA-positive, EDTA-positive, and MHT-positive plus PBA-negative plus EDTA-negative, had excellent sensitivity and specificity for the detection of KPC- (100% sensitivity and 100% specificity), MBL- (94% sensitivity and 100% specificity), and OXA-48-like-producing isolates (100% sensitivity and 100% specificity), respectively. Combined use of the MHT and CIT with PBA and EDTA, for the detection of CPE and MBL-producing Pseudomonas spp., is effective in detecting and characterizing carbapenemases in routine laboratories.

Rapid and Complete Enzyme Hydrolysis of Lignocellulosic Nanofibrils

Science.gov (United States)

Raquel Martin-Sampedro; Ilari Filpponen; Ingrid C. Hoeger; J.Y. Zhu; Janne Laine; Orlando J. Rojas

2012-01-01

Rapid enzymatic saccharification of lignocellulosic nanofibrils (LCNF) was investigated by monitoring nanoscale changes in mass via quartz crystal microgravimetry and also by measuring reducing sugar yields. In only a few minutes LCNF thin films were completely hydrolyzed upon incubation in multicomponent enzyme systems. Conversion to sugars and oligosaccharides of...

County-Scale Spatial Distribution of Soil Enzyme Activities and Enzyme Activity Indices in Agricultural Land: Implications for Soil Quality Assessment

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Xiangping Tan

2014-01-01

Full Text Available Here the spatial distribution of soil enzymatic properties in agricultural land was evaluated on a county-wide (567 km2 scale in Changwu, Shaanxi Province, China. The spatial variations in activities of five hydrolytic enzymes were examined using geostatistical methods. The relationships between soil enzyme activities and other soil properties were evaluated using both an integrated total enzyme activity index (TEI and the geometric mean of enzyme activities (GME. At the county scale, soil invertase, phosphatase, and catalase activities were moderately spatially correlated, whereas urease and dehydrogenase activities were weakly spatially correlated. Correlation analysis showed that both TEI and GME were better correlated with selected soil physicochemical properties than single enzyme activities. Multivariate regression analysis showed that soil OM content had the strongest positive effect while soil pH had a negative effect on the two enzyme activity indices. In addition, total phosphorous content had a positive effect on TEI and GME in orchard soils, whereas alkali-hydrolyzable nitrogen and available potassium contents, respectively, had negative and positive effects on these two enzyme indices in cropland soils. The results indicate that land use changes strongly affect soil enzyme activities in agricultural land, where TEI provides a sensitive biological indicator for soil quality.

High inorganic triphosphatase activities in bacteria and mammalian cells: identification of the enzymes involved.

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Gregory Kohn

Full Text Available BACKGROUND: We recently characterized a specific inorganic triphosphatase (PPPase from Nitrosomonas europaea. This enzyme belongs to the CYTH superfamily of proteins. Many bacterial members of this family are annotated as predicted adenylate cyclases, because one of the founding members is CyaB adenylate cyclase from A. hydrophila. The aim of the present study is to determine whether other members of the CYTH protein family also have a PPPase activity, if there are PPPase activities in animal tissues and what enzymes are responsible for these activities. METHODOLOGY/PRINCIPAL FINDINGS: Recombinant enzymes were expressed and purified as GST- or His-tagged fusion proteins and the enzyme activities were determined by measuring the release of inorganic phosphate. We show that the hitherto uncharacterized E. coli CYTH protein ygiF is a specific PPPase, but it contributes only marginally to the total PPPase activity in this organism, where the main enzyme responsible for hydrolysis of inorganic triphosphate (PPP(i is inorganic pyrophosphatase. We further show that CyaB hydrolyzes PPP(i but this activity is low compared to its adenylate cyclase activity. Finally we demonstrate a high PPPase activity in mammalian and quail tissue, particularly in the brain. We show that this activity is mainly due to Prune, an exopolyphosphatase overexpressed in metastatic tumors where it promotes cell motility. CONCLUSIONS AND GENERAL SIGNIFICANCE: We show for the first time that PPPase activities are widespread in bacteria and animals. We identified the enzymes responsible for these activities but we were unable to detect significant amounts of PPP(i in E. coli or brain extracts using ion chromatography and capillary electrophoresis. The role of these enzymes may be to hydrolyze PPP(i, which could be cytotoxic because of its high affinity for Ca(2+, thereby interfering with Ca(2+ signaling.

RR Lyrae star distance scale and kinematics from inner bulge to 50 kpc

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Dambis Andrei

2017-01-01

Full Text Available We use the currently most complete sample of ∼ 3500 type ab RR Lyraes in our Galaxy with available radial-velocity and [Fe/H] measurements to perform a statisticalparallax analysis for a subsample of ∼ 600 type ab RR Lyraes located within 5 kpc from the Sun to refine the parameters of optical and WISE W1-band period-metallicityluminosity relations and adjust our preliminary distances. The new zero point implies the rescaled estimates for the solar Galactocentric distance (RG = 7.99 ± 0.37 kpc and the LMC distance modulus (DMLMC = 18.39 ±0.09. We use the kinematic data for the entire sample to explore the dependence of the halo and thick-disk RR Lyrae velocity ellipsoids on Galactocentric distance from the inner bulge out to R ∼ 50 kpc.

Carbapenem-Resistant Acinetobacter baumannii and Enterobacteriaceae in South and Southeast Asia

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Apisarnthanarak, Anucha; Khan, Erum; Ghafur, Abdul

2016-01-01

SUMMARY Carbapenem-resistant Gram-negative bacteria, in particular the Acinetobacter baumannii-calcoaceticus complex and Enterobacteriaceae, are escalating global public health threats. We review the epidemiology and prevalence of these carbapenem-resistant Gram-negative bacteria among countries in South and Southeast Asia, where the rates of resistance are some of the highest in the world. These countries house more than a third of the world's population, and several are also major medical tourism destinations. There are significant data gaps, and the almost universal lack of comprehensive surveillance programs that include molecular epidemiologic testing has made it difficult to understand the origins and extent of the problem in depth. A complex combination of factors such as inappropriate prescription of antibiotics, overstretched health systems, and international travel (including the phenomenon of medical tourism) probably led to the rapid rise and spread of these bacteria in hospitals in South and Southeast Asia. In India, Pakistan, and Vietnam, carbapenem-resistant Enterobacteriaceae have also been found in the environment and community, likely as a consequence of poor environmental hygiene and sanitation. Considerable political will and effort, including from countries outside these regions, are vital in order to reduce the prevalence of such bacteria in South and Southeast Asia and prevent their global spread. PMID:27795305

Carbapenem-Resistant Acinetobacter baumannii and Enterobacteriaceae in South and Southeast Asia.

Science.gov (United States)

Hsu, Li-Yang; Apisarnthanarak, Anucha; Khan, Erum; Suwantarat, Nuntra; Ghafur, Abdul; Tambyah, Paul Anantharajah

2017-01-01

Carbapenem-resistant Gram-negative bacteria, in particular the Acinetobacter baumannii-calcoaceticus complex and Enterobacteriaceae, are escalating global public health threats. We review the epidemiology and prevalence of these carbapenem-resistant Gram-negative bacteria among countries in South and Southeast Asia, where the rates of resistance are some of the highest in the world. These countries house more than a third of the world's population, and several are also major medical tourism destinations. There are significant data gaps, and the almost universal lack of comprehensive surveillance programs that include molecular epidemiologic testing has made it difficult to understand the origins and extent of the problem in depth. A complex combination of factors such as inappropriate prescription of antibiotics, overstretched health systems, and international travel (including the phenomenon of medical tourism) probably led to the rapid rise and spread of these bacteria in hospitals in South and Southeast Asia. In India, Pakistan, and Vietnam, carbapenem-resistant Enterobacteriaceae have also been found in the environment and community, likely as a consequence of poor environmental hygiene and sanitation. Considerable political will and effort, including from countries outside these regions, are vital in order to reduce the prevalence of such bacteria in South and Southeast Asia and prevent their global spread. Copyright © 2016 American Society for Microbiology.

Could Frequent Carbapenem Use Be a Risk Factor for Colistin Resistance?

Science.gov (United States)

Gundogdu, Aycan; Ulu-Kilic, Aysegul; Kilic, Huseyin; Ozhan, Esra; Altun, Dilek; Cakir, Ozlem; Alp, Emine

2017-10-13

The antibiotic colistin, which had been previously abandoned, is being brought back as a last line of defense against bacterial infection. However, colistin resistance was reported shortly after its reintroduction. This study evaluated the risk factors for colonization/infections due to colistin-resistant Acinetobacter baumannii (ColR-Ab) and Klebsiella pneumoniae (ColR-Kp) strains and characterized the molecular epidemiology of these two strains. Age, previous hospitalization duration, and previous use of carbapenem and colistin were risk factors for ColR-Kp, whereas previous use of carbapenem and colistin was a risk factor for ColR-Ab. According to pulsed-field gel electrophoresis analysis, most ColR-Kp strains could be grouped into two major pulsotypes. This appears to be an indicator of cross contamination of ColR-Kp strain, since different isolates appeared to be belonging to the same clones. The existence of colistin-susceptible (ColS) and colistin-resistant (ColR) strains in the same pulsotypes might also be an indicator of the recent emergence of resistance mechanisms. The results highlight the emergence of ColR pathogens in Turkey, which is considered to be developing country, and that carbapenem use coupled with insufficient infection control measures might increase the risk of ColR outbreaks.

Exploitation of starch industry liquid by-product to produce bioactive peptides from rice hydrolyzed proteins.

Science.gov (United States)

Dei Piu', Lucilla; Tassoni, Annalisa; Serrazanetti, Diana Isabella; Ferri, Maura; Babini, Elena; Tagliazucchi, Davide; Gianotti, Andrea

2014-07-15

Small peptides show higher antioxidant capacity than native proteins and may be absorbed in the intestine without further digestion. In our study, a protein by-product from rice starch industry was hydrolyzed with commercial proteolytic enzymes (Alcalase, Neutrase, Flavourzyme) and microbial whole cells of Bacillus spp. and the released peptides were tested for antioxidant activity. Among enzymes, Alcalase was the most performing, while microbial proteolytic activity was less efficient. Conversely, the antioxidant activity was higher in the samples obtained by microbial hydrolysis and particularly with Bacillus pumilus AG1. The sequences of low molecular weight antioxidant peptides were determined and analyzed for aminoacidic composition. The results obtained so far suggest that the hydrolytic treatment of this industrial by-product, with selected enzymes and microbial systems, can allow its exploitation for the production of functional additives and supplements rich in antioxidant peptides, to be used in new food formulas for human consumption. Copyright © 2014 Elsevier Ltd. All rights reserved.

Site-specific DNA transesterification catalyzed by a restriction enzyme

OpenAIRE

Sasnauskas, Giedrius; Connolly, Bernard A.; Halford, Stephen E.; Siksnys, Virginijus

2007-01-01

Most restriction endonucleases use Mg2+ to hydrolyze phosphodiester bonds at specific DNA sites. We show here that BfiI, a metal-independent restriction enzyme from the phospholipase D superfamily, catalyzes both DNA hydrolysis and transesterification reactions at its recognition site. In the presence of alcohols such as ethanol or glycerol, it attaches the alcohol covalently to the 5′ terminus of the cleaved DNA. Under certain conditions, the terminal 3′-OH of one DNA strand can attack the t...

Emergence of KPC-producing Klebsiella pneumoniae ST512 isolated from cerebrospinal fluid of a child in Algeria

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S. Bakour

2015-01-01

Full Text Available We report class A carbapenemase (KPC-3-producing Klebsiella pneumoniae meningitis in a 6-month-old child in Algeria. Multilocus sequence typing showed that the sequence type obtained corresponded to ST512, an allelic single-locus variant of the pandemic ST258 widely distributed in KPC producers from Europe. To our knowledge, this is the first report of KPC-3-producing K. pneumoniae ST512 in a North African country.

Carbapenem therapy is associated with improved survival compared with piperacillin-tazobactam for patients with extended-spectrum β-lactamase bacteremia.

Science.gov (United States)

Tamma, Pranita D; Han, Jennifer H; Rock, Clare; Harris, Anthony D; Lautenbach, Ebbing; Hsu, Alice J; Avdic, Edina; Cosgrove, Sara E

2015-05-01

The effectiveness of piperacillin-tazobactam (PTZ) for the treatment of extended-spectrum β-lactamase (ESBL) bacteremia is controversial. We compared 14-day mortality of PTZ vs carbapenems as empiric therapy in a cohort of patients with ESBL bacteremia who all received definitive therapy with a carbapenem. Patients hospitalized between January 2007 and April 2014 with monomicrobial ESBL bacteremia were included. A decrease of >3 doubling dilutions in the minimum inhibitory concentration for third-generation cephalosporins tested in combination with 4 µg/mL of clavulanic acid was used to confirm ESBL status. The primary exposure was empiric therapy, defined as antibiotic therapy administered to a patient before ESBL status was known. Patients were excluded if they did not receive a carbapenem after ESBL production was identified. The primary outcome was time to death from the first day of bacteremia. Propensity scores using inverse probability of exposure weighting (IPW) were used to estimate the probability that a patient would receive PTZ vs carbapenems empirically. We calculated overall hazard ratios for mortality censored at 14 days using Cox proportional hazards models on an IPW-adjusted cohort. A total of 331 unique patients with ESBL bacteremia were identified. One hundred three (48%) patients received PTZ empirically and 110 (52%) received carbapenems empirically. The adjusted risk of death was 1.92 times higher for patients receiving empiric PTZ compared with empiric carbapenem therapy (95% confidence interval, 1.07-3.45). PTZ appears inferior to carbapenems for the treatment of ESBL bacteremia. For patients at high risk of invasive ESBL infections, early carbapenem therapy should be considered. Our findings should not be extended to β-lactam/β-lactamase inhibitor combinations in development, as limited clinical data are available for these agents. © The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of

A systematic review and meta-Analyses show that carbapenem use and medical devices are the leading risk factors for carbapenem- resistant pseudomonas aeruginosa

NARCIS (Netherlands)

A.F. Voor (Anne); J.A. Severin (Juliëtte); E.M.E.H. Lesaffre (Emmanuel); M.C. Vos (Margreet)

2014-01-01

textabstractA systematic review and meta-Analyses were performed to identify the risk factors associated with carbapenem-resistant Pseudomonas aeruginosa and to identify sources and reservoirs for the pathogen. A systematic search of PubMed and Embase databases from 1 January 1987 until 27 January

Risk Factors for Carbapenemase-Producing Carbapenem-Resistant Enterobacteriaceae (CP-CRE) Acquisition Among Contacts of Newly Diagnosed CP-CRE Patients.

Science.gov (United States)

Schwartz-Neiderman, Anat; Braun, Tali; Fallach, Noga; Schwartz, David; Carmeli, Yehuda; Schechner, Vered

2016-10-01

OBJECTIVE Carbapenemase-producing carbapenem-resistant Enterobacteriaceae (CP-CRE) are extremely drug-resistant pathogens. Screening of contacts of newly identified CP-CRE patients is an important step to limit further transmission. We aimed to determine the risk factors for CP-CRE acquisition among patients exposed to a CP-CRE index patient. METHODS A matched case-control study was performed in a tertiary care hospital in Israel. The study population was comprised of patients who underwent rectal screening for CP-CRE following close contact with a newly identified CP-CRE index patient. Cases were defined as positive tests for CP-CRE. For each case patient, 2 matched controls were randomly selected from the pool of contacts who tested negative for CP-CRE following exposure to the same index case. Bivariate and multivariate analyses were conducted using conditional logistic regression. RESULTS In total, 53 positive contacts were identified in 40 unique investigations (896 tests performed on 735 contacts) between October 6, 2008, and June 7, 2012. bla KPC was the only carbapenemase identified. In multivariate analysis, risk factors for CP-CRE acquisition among contacts were (1) contact with an index patient for ≥3 days (odds ratio [OR], 9.8; 95% confidence interval [CI], 2.0-48.9), (2) mechanical ventilation (OR, 4.1; 95% CI, 1.4-11.9), and (3) carriage or infection with another multidrug-resistant organism (MDRO; OR, 2.6; 95% CI, 1.0-7.1). Among patients who received antibiotics, cephalosporins were associated with a lower risk of acquisition. CONCLUSIONS Patient characteristics (ventilation and carriage of another MDRO) as well as duration of contact are risk factors for CP-CRE acquisition among contacts. The role of cephalosporins requires further study. Infect Control Hosp Epidemiol 2016;1-7.

Development of methods and systems for preparing hydrolyzates for acetone-butanol fermentation

Energy Technology Data Exchange (ETDEWEB)

Nakhmanovich, B M

1967-01-01

Optimal conditions for hydrolysis of vegetable waste material, e.g., maize stalks, sunflower parings, and hemp wastes, with concentrated or dilute H/sub 2/SO/sub 4/ were established. Hydrolyzates were neutralized with Ca(OH)/sub 2/ to pH 5.5 to 6.0 and the supernatant was sterilized at 110 to 115/sup 0/ for 15 to 20 minutes and used for fermentation in mixtures with molasses or mash. The maximum amount of fermentation inhibitors which can be present in hydrolyzate is: 0.1% furfural, 0.03% HCO/sub 2/H and 0.001% As.

MCR-1 and OXA-48 In Vivo Acquisition in KPC-Producing Escherichia coli after Colistin Treatment.

Science.gov (United States)

Beyrouthy, Racha; Robin, Frederic; Lessene, Aude; Lacombat, Igor; Dortet, Laurent; Naas, Thierry; Ponties, Valérie; Bonnet, Richard

2017-08-01

The spread of mcr-1 -encoding plasmids into carbapenem-resistant Enterobacteriaceae raises concerns about the emergence of untreatable bacteria. We report the acquisition of mcr-1 in a carbapenem-resistant Escherichia coli strain after a 3-week course of colistin in a patient repatriated to France from Portugal. Whole-genome sequencing revealed that the Klebsiella pneumoniae carbapenemase-producing E. coli strain acquired two plasmids, an IncL OXA-48-encoding plasmid and an IncX4 mcr-1 -encoding plasmid. This is the first report of mcr-1 in carbapenemase-encoding bacteria in France. Copyright © 2017 American Society for Microbiology.

Biochemical and mass spectrometric characterization of human N-acylethanolamine-hydrolyzing acid amidase inhibition.

Directory of Open Access Journals (Sweden)

Jay M West

Full Text Available The mechanism of inactivation of human enzyme N-acylethanolamine-hydrolyzing acid amidase (hNAAA, with selected inhibitors identified in a novel fluorescent based assay developed for characterization of both reversible and irreversible inhibitors, was investigated kinetically and using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS. 1-Isothiocyanatopentadecane (AM9023 was found to be a potent, selective and reversible hNAAA inhibitor, while two others, 5-((biphenyl-4-ylmethyl-N,N-dimethyl-2H-tetrazole-2-carboxamide (AM6701 and N-Benzyloxycarbonyl-L-serine β-lactone (N-Cbz-serine β-lactone, inhibited hNAAA in a covalent and irreversible manner. MS analysis of the hNAAA/covalent inhibitor complexes identified modification only of the N-terminal cysteine (Cys126 of the β-subunit, confirming a suggested mechanism of hNAAA inactivation by the β-lactone containing inhibitors. These experiments provide direct evidence of the key role of Cys126 in hNAAA inactivation by different classes of covalent inhibitors, confirming the essential role of cysteine for catalysis and inhibition in this cysteine N-terminal nucleophile hydrolase enzyme. They also provide a methodology for the rapid screening and characterization of large libraries of compounds as potential inhibitors of NAAA, and subsequent characterization or their mechanism through MALDI-TOF MS based bottom up-proteomics.

Substrates and method for determining enzymes

Science.gov (United States)

Smith, R.E.; Bissell, E.R.

1981-10-13

A method is disclosed for determining the presence of an enzyme in a biological fluid, which includes the steps of contacting the fluid with a synthetic chromogenic substrate, which is an amino acid derivative of 7-amino-4-trifluoromethylcoumarin; incubating the substrate-containing fluid to effect enzymatic hydrolysis; and fluorometrically determining the presence of the free 7-amino-4-trifluoromethylcoumarin chromophore in the hydrolyzate. No Drawings

The Epidemiology of Carbapenem-Resistant Enterobacteriaceae: The Impact and Evolution of a Global Menace

Science.gov (United States)

Weinstein, Robert A.

2017-01-01

Abstract Carbapenem-resistant Enterobacteriaceae (CRE) are a serious public health threat. Infections due to these organisms are associated with significant morbidity and mortality. Mechanisms of drug resistance in gram-negative bacteria (GNB) are numerous; β-lactamase genes carried on mobile genetic elements are a key mechanism for the rapid spread of antibiotic-resistant GNB worldwide. Transmissible carbapenem-resistance in Enterobacteriaceae has been recognized for the last 2 decades, but global dissemination of carbapenemase-producing Enterobacteriaceae (CPE) is a more recent problem that, once initiated, has been occurring at an alarming pace. In this article, we discuss the evolution of CRE, with a focus on the epidemiology of the CPE pandemic; review risk factors for colonization and infection with the most common transmissible CPE worldwide, Klebsiella pneumoniae carbapenemase–producing K. pneumoniae; and present strategies used to halt the striking spread of these deadly pathogens. PMID:28375512

Dipeptidyl peptidase IV inhibitory activity of protein hydrolyzates ...

African Journals Online (AJOL)

Background: Type 2 diabetes is a chronic metabolic disorder. Recently, dipeptidyl peptidase IV (DPP-IV) inhibitors that protect incretin hormones from being cleaved by DPP-IV have been used as drugs to control glycemia. This study examined the potential hypoglycemic effect of amaranth grain storage protein hydrolyzates ...

Involvement of Lipid Metabolism in the Action of Phospholipase A2 Neurotoxins

Science.gov (United States)

1992-04-15

activity by 50% toward an egg yolk substrate, but had no effect on hydrolysis of a lecithin substrate (Rosenberg et al., 1989). Lethality was not...etc.) hydrolyzed , not molecular species as evidenced in a recent review (Harris, 1985). The existence of reacylating enzymes in tissues that "restore...34 the hydrolyzed PL by attaching another FFA on to it would mean PLs will appear not to have been hydrolyzed at levels of PLA 2 activity less than the

Carbapenem-resistant Pseudomonas aeruginosa: association with virulence genes and biofilm formation

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Iara Rossi Gonçalves

Full Text Available Abstract Pseudomonas aeruginosa is an opportunistic pathogen that causes frequently nosocomial infections, currently becoming more difficult to treat due to the various resistance mechanisms and different virulence factors. The purpose of this study was to determine the risk factors independently associated with the development of bacteremia by carbapenem-resistant P. aeruginosa, the frequency of virulence genes in metallo-β-lactamases producers and to evaluate their ability to produce biofilm. We conducted a case–control study in the Uberlândia Federal University – Hospital Clinic, Brazil. Polymerase Chain Reaction was performed for metallo-β-lactamases and virulence genes. Adhesion and biofilm assays were done by quantitative tests. Among the 157 strains analyzed, 73.9% were multidrug-resistant, 43.9% were resistant to carbapenems, 16.1% were phenotypically positive for metallo-β-lactamases, and of these, 10.7% were positive for blaSPM gene and 5.3% positive for blaVIM. The multivariable analysis showed that mechanical ventilation, enteral/nasogastric tubes, primary bacteremia with unknown focus, and inappropriate therapy were independent risk factors associated with bacteremia. All tested strains were characterized as strongly biofilm producers. A higher mortality was found among patients with bacteremia by carbapenem-resistant P. aeruginosa strains, associated independently with extrinsic risk factors, however it was not evident the association with the presence of virulence and metallo-β-lactamases genes.

Comparative lipid production by oleaginous yeasts in hydrolyzates of lignocellulosic biomass and process strategy for high titers.

Science.gov (United States)

Slininger, Patricia J; Dien, Bruce S; Kurtzman, Cletus P; Moser, Bryan R; Bakota, Erica L; Thompson, Stephanie R; O'Bryan, Patricia J; Cotta, Michael A; Balan, Venkatesh; Jin, Mingjie; Sousa, Leonardo da Costa; Dale, Bruce E

2016-08-01

Oleaginous yeasts can convert sugars to lipids with fatty acid profiles similar to those of vegetable oils, making them attractive for production of biodiesel. Lignocellulosic biomass is an attractive source of sugars for yeast lipid production because it is abundant, potentially low cost, and renewable. However, lignocellulosic hydrolyzates are laden with byproducts which inhibit microbial growth and metabolism. With the goal of identifying oleaginous yeast strains able to convert plant biomass to lipids, we screened 32 strains from the ARS Culture Collection, Peoria, IL to identify four robust strains able to produce high lipid concentrations from both acid and base-pretreated biomass. The screening was arranged in two tiers using undetoxified enzyme hydrolyzates of ammonia fiber expansion (AFEX)-pretreated cornstover as the primary screening medium and acid-pretreated switch grass as the secondary screening medium applied to strains passing the primary screen. Hydrolyzates were prepared at ∼18-20% solids loading to provide ∼110 g/L sugars at ∼56:39:5 mass ratio glucose:xylose:arabinose. A two stage process boosting the molar C:N ratio from 60 to well above 400 in undetoxified switchgrass hydrolyzate was optimized with respect to nitrogen source, C:N, and carbon loading. Using this process three strains were able to consume acetic acid and nearly all available sugars to accumulate 50-65% of cell biomass as lipid (w/w), to produce 25-30 g/L lipid at 0.12-0.22 g/L/h and 0.13-0.15 g/g or 39-45% of the theoretical yield at pH 6 and 7, a performance unprecedented in lignocellulosic hydrolyzates. Three of the top strains have not previously been reported for the bioconversion of lignocellulose to lipids. The successful identification and development of top-performing lipid-producing yeast in lignocellulose hydrolyzates is expected to advance the economic feasibility of high quality biodiesel and jet fuels from renewable biomass, expanding the market

Modified Carbapenem Inactivation Method for Phenotypic Detection of Carbapenemase Production among Enterobacteriaceae.

Science.gov (United States)

Pierce, Virginia M; Simner, Patricia J; Lonsway, David R; Roe-Carpenter, Darcie E; Johnson, J Kristie; Brasso, William B; Bobenchik, April M; Lockett, Zabrina C; Charnot-Katsikas, Angella; Ferraro, Mary Jane; Thomson, Richard B; Jenkins, Stephen G; Limbago, Brandi M; Das, Sanchita

2017-08-01

The ability of clinical microbiology laboratories to reliably detect carbapenemase-producing carbapenem-resistant Enterobacteriaceae (CP-CRE) is an important element of the effort to prevent and contain the spread of these pathogens and an integral part of antimicrobial stewardship. All existing methods have limitations. A new, straightforward, inexpensive, and specific phenotypic method for the detection of carbapenemase production, the carbapenem inactivation method (CIM), was recently described. Here we describe a two-stage evaluation of a modified carbapenem inactivation method (mCIM), in which tryptic soy broth was substituted for water during the inactivation step and the length of this incubation was extended. A validation study was performed in a single clinical laboratory to determine the accuracy of the mCIM, followed by a nine-laboratory study to verify the reproducibility of these results and define the zone size cutoff that best discriminated between CP-CRE and members of the family Enterobacteriaceae that do not produce carbapenemases. Bacterial isolates previously characterized through whole-genome sequencing or targeted PCR as to the presence or absence of carbapenemase genes were tested for carbapenemase production using the mCIM; isolates with Ambler class A, B, and D carbapenemases, non-CP-CRE isolates, and carbapenem-susceptible isolates were included. The sensitivity of the mCIM observed in the validation study was 99% (95% confidence interval [95% CI], 93% to 100%), and the specificity was 100% (95% CI, 82% to 100%). In the second stage of the study, the range of sensitivities observed across nine laboratories was 93% to 100%, with a mean of 97%; the range of specificities was 97% to 100%, with a mean of 99%. The mCIM was easy to perform and interpret for Enterobacteriaceae , with results in less than 24 h and excellent reproducibility across laboratories. Copyright © 2017 American Society for Microbiology.

Carbapenem-Resistant E. cloacae in Southwest China: Molecular Analysis of Resistance and Risk Factors for Infections Caused by NDM-1-Producers

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Xiaojiong Jia

2018-04-01

Full Text Available Carbapenem-resistant Enterobacteriaceae (CRE has been considered a serious global threat, but carbapenem resistance remains relatively uncommon in E. cloacae, especially in China. The aim of this study was to characterize carbapenem-resistant E. cloacae (CR-ECL isolates from 2012 to 2016 in Southwest China. Our study revealed that 20 (15.2% of the 132 CR-ECL isolates obtained from patients were identified as NDM-1, with most isolates carrying the IncFIIA plasmids. Notably, we initially observed that the E. cloacae strain co-harbored NDM-1 and IMP-8 carbapenemases simultaneously. Analysis of the genetic environment of these two genes has revealed that the highly conserved regions (blaNDM-1-bleMBL-trpF-tat are associated with the dissemination of NDM-1, while IS26, intI1, and tniC could be involved in the spread of IMP-8. Molecular epidemiology studies showed the nosocomial outbreak caused by NDM-1-producing E. cloacae ST88. Transferring from another hospital and previous carbapenem exposure were identified as independent risk factors for the acquisition of NDM-1-producing E. cloacae. These findings emphasize the need for intensive surveillance and precautions to monitor the further spread of NDM-1 in China.

Reconstitution of a thermostable xylan-degrading enzyme mixture from the bacterium Caldicellulosiruptor bescii.

Science.gov (United States)

Su, Xiaoyun; Han, Yejun; Dodd, Dylan; Moon, Young Hwan; Yoshida, Shosuke; Mackie, Roderick I; Cann, Isaac K O

2013-03-01

Xylose, the major constituent of xylans, as well as the side chain sugars, such as arabinose, can be metabolized by engineered yeasts into ethanol. Therefore, xylan-degrading enzymes that efficiently hydrolyze xylans will add value to cellulases used in hydrolysis of plant cell wall polysaccharides for conversion to biofuels. Heterogeneous xylan is a complex substrate, and it requires multiple enzymes to release its constituent sugars. However, the components of xylan-degrading enzymes are often individually characterized, leading to a dearth of research that analyzes synergistic actions of the components of xylan-degrading enzymes. In the present report, six genes predicted to encode components of the xylan-degrading enzymes of the thermophilic bacterium Caldicellulosiruptor bescii were expressed in Escherichia coli, and the recombinant proteins were investigated as individual enzymes and also as a xylan-degrading enzyme cocktail. Most of the component enzymes of the xylan-degrading enzyme mixture had similar optimal pH (5.5 to ∼6.5) and temperature (75 to ∼90°C), and this facilitated their investigation as an enzyme cocktail for deconstruction of xylans. The core enzymes (two endoxylanases and a β-xylosidase) exhibited high turnover numbers during catalysis, with the two endoxylanases yielding estimated k(cat) values of ∼8,000 and ∼4,500 s(-1), respectively, on soluble wheat arabinoxylan. Addition of side chain-cleaving enzymes to the core enzymes increased depolymerization of a more complex model substrate, oat spelt xylan. The C. bescii xylan-degrading enzyme mixture effectively hydrolyzes xylan at 65 to 80°C and can serve as a basal mixture for deconstruction of xylans in bioenergy feedstock at high temperatures.

Interaction between chitosan and its related enzymes: A review.

Science.gov (United States)

Shinya, Shoko; Fukamizo, Tamo

2017-11-01

Chitosan-related enzymes including chitosanases, exo-β-glucosaminidases, and enzymes having chitosan-binding modules recognize ligands through electrostatic interactions between the acidic amino acids in proteins and amino groups of chitosan polysaccharides. However, in GH8 chitosanases, several aromatic residues are also involved in substrate recognition through stacking interactions, and these enzymes consequently hydrolyze β-1,4-glucan as well as chitosan. The binding grooves of these chitosanases are extended and opened at both ends of the grooves, so that the enzymes can clamp a long chitosan polysaccharide. The association/dissociation of positively charged glucosamine residues to/from the binding pocket of a GH2 exo-β-glucosaminidase controls the p K a of the catalytic acid, thereby maintaining the high catalytic potency of the enzyme. In contrast to chitosanases, chitosan-binding modules only accommodate a couple of glucosamine residues, predominantly recognizing the non-reducing end glucosamine residue of chitosan by electrostatic interactions and a hydrogen-bonding network. These structural findings on chitosan-related enzymes may contribute to future applications for the efficient conversion of the chitin/chitosan biomass. Copyright © 2017 Elsevier B.V. All rights reserved.

Action of amylolytic and pullulytic enzymes from various anaerobic thermophiles on linear and branched glucose polymers

Energy Technology Data Exchange (ETDEWEB)

Koch, R [Goettingen Univ. (Germany, F.R.). Inst. fuer Mikrobiologie; Antranikian, G [Technische Univ. Hamburg-Harburg, Hamburg (Germany, F.R.). Arbeitsbereich Biotechnologie 1

1990-10-01

A detailed study has been conducted on the action of starch hydrolyzing enzymes from thermophilic anaerobic bacteria belonging to the genera Clostridium, Thermoanaerobacter and Thermobacteroides. The appearance of multiple bands on polyacrylamide gels with amylolytic as well as pullulytic activities was shown to be a general feature of bacteria investigated. Analysis of the hydrolysis products of each protein band clearly demonstrated the capability of these organisms to hydrolyze {alpha}-1,4-glycosidic bonds in linear oligosaccharides and {alpha}-1,6-glycosidic linkages in pullulan. Furthermore, the enzyme system of thermophilic bacteria investigated was also capable of attacking in the {alpha}-1,6-linkages in branched oligosaccharides. Due to the action of these thermoactive enzymes with multiple specificity an almost complete hydrolysis of raw starch and maltodextrin could be achieved under the same conditions and in one step. (orig.).

Bioethanol from lignocellulose - pretreatment, enzyme immobilization and hydrolysis kinetics

DEFF Research Database (Denmark)

Tsai, Chien Tai

, the cost of enzyme is still the bottle neck, re-using the enzyme is apossible way to reduce the input of enzyme in the process. In the point view of engineering, the prediction of enzymatic hydrolysis kinetics under different substrate loading, enzyme combination is usful for process design. Therefore...... lignocellulose is the required high cellulase enzyme dosages that increase the processing costs. One method to decrease the enzyme dosage is to re-use BG, which hydrolyze the soluble substrate cellobiose. Based on the hypothesis that immobilized BG can be re-used, how many times the enzyme could be recycled...... liquid and pretreatment time can be reduced, the influence of substrate concentration, pretreatment time and temperature were investigated and optimized. Pretreatment of barley straw by [EMIM]Ac, correlative models were constructed using 3 different pretreatment parameters (temperature, time...

Novel photoluminescence enzyme immunoassay based on supramolecular host-guest recognition using L-arginine/6-aza-2-thiothymine-stabilized gold nanocluster.

Science.gov (United States)

Wang, Youmei; Lu, Minghua; Tang, Dianping

2018-06-30

A new photoluminescence (PL) enzyme immunoassay was designed for sensitive detection of aflatoxin B 1 (AFB 1 ) via an innovative enzyme substrate, 6-aza-2-thiothymine-stabilized gold nanocluster (AAT-AuNC) with L-arginine. The enzyme substrate with strong PL intensity was formed through supramolecular host-guest assembly between guanidine group of L-arginine and AAT capped on the surface of AuNC. Upon arginase introduction, the captured L-arginine was hydrolyzed into ornithine and urea, thus resulting in the decreasing PL intensity. Based on this principle, a novel competitive-type immunoreaction was first carried out on AFB 1 -bovine serum albumin (AFB 1 -BSA) conjugate-coated microplate, using arginase-labeled anti-AFB 1 antibody as the competitor. Under the optimum conditions, the PL intensity increased with the increment of target AFB 1 , and allowed the detection of the analyte at concentrations as low as 3.2 pg mL -1 (ppt). Moreover, L-arginine-AAT-AuNC-based PL enzyme immunoassay afforded good reproducibility and acceptable specificity. In addition, the accuracy of this methodology, referring to commercial AFB 1 ELISA kit, was evaluated to analyze naturally contaminated or spiked peanut samples, giving well-matched results between two methods, thus representing a useful scheme for practical application in quantitative monitoring of mycotoxins in foodstuff. Copyright © 2018 Elsevier B.V. All rights reserved.

Cohnella amylopullulanases: Biochemical characterization of two recombinant thermophilic enzymes.

Directory of Open Access Journals (Sweden)

Fatemeh Zebardast Roodi

Full Text Available Some industries require newer, more efficient recombinant enzymes to accelerate their ongoing biochemical reactions in harsh environments with less replenishment. Thus, the search for native enzymes from extremophiles that are suitable for use under industrial conditions is a permanent challenge for R & D departments. Here and toward such discoveries, two sequences homologous to amylopullulanases (EC 3.2.1.41, GH57 from an endogenous Cohnella sp., [Coh00831 (KP335161; 1998 bp and Coh01133 (KP335160: 3678 bp] were identified. The genes were heterologously expressed in E. coli to both determine their type and further characterize their properties. The isolated DNA was PCR amplified with gene specific primers and cloned in pET28a, and the recombinant proteins were expressed in E. coli BL21 (DE3. The temperatures and pH optima of purified recombinants Coh 01133 and Coh 00831 enzymes were 70°C and 8, and 60°C and 6, respectively. These enzymes are stable more than 90% in 60°C and 50°C for 90 min respectively. The major reactions released sugars which could be fractionated by HPLC analysis, from soluble starch were mainly maltose (G2, maltotriose (G3 and maltotetraose (G4. The enzymes hydrolyzed pullulan to maltotriose (G3 only. Enzyme activities for both proteins were improved in the availability of Mn2+, Ba2+, Ca2+, and Mg2+ and reduced in the presence of Fe2+, Li2+, Na2+, Triton X100 and urea. Moreover, Co2+, K+, and Cu2+ had a negative effect only on Coh 01133 enzyme.

Cohnella amylopullulanases: Biochemical characterization of two recombinant thermophilic enzymes.

Science.gov (United States)

Zebardast Roodi, Fatemeh; Aminzadeh, Saeed; Farrokhi, Naser; Karkhane, AliAsghar; Haghbeen, Kamahldin

2017-01-01

Some industries require newer, more efficient recombinant enzymes to accelerate their ongoing biochemical reactions in harsh environments with less replenishment. Thus, the search for native enzymes from extremophiles that are suitable for use under industrial conditions is a permanent challenge for R & D departments. Here and toward such discoveries, two sequences homologous to amylopullulanases (EC 3.2.1.41, GH57) from an endogenous Cohnella sp., [Coh00831 (KP335161; 1998 bp) and Coh01133 (KP335160: 3678 bp)] were identified. The genes were heterologously expressed in E. coli to both determine their type and further characterize their properties. The isolated DNA was PCR amplified with gene specific primers and cloned in pET28a, and the recombinant proteins were expressed in E. coli BL21 (DE3). The temperatures and pH optima of purified recombinants Coh 01133 and Coh 00831 enzymes were 70°C and 8, and 60°C and 6, respectively. These enzymes are stable more than 90% in 60°C and 50°C for 90 min respectively. The major reactions released sugars which could be fractionated by HPLC analysis, from soluble starch were mainly maltose (G2), maltotriose (G3) and maltotetraose (G4). The enzymes hydrolyzed pullulan to maltotriose (G3) only. Enzyme activities for both proteins were improved in the availability of Mn2+, Ba2+, Ca2+, and Mg2+ and reduced in the presence of Fe2+, Li2+, Na2+, Triton X100 and urea. Moreover, Co2+, K+, and Cu2+ had a negative effect only on Coh 01133 enzyme.

A coarse-grained model for synergistic action of multiple enzymes on cellulose

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Asztalos Andrea

2012-08-01

Full Text Available Abstract Background Degradation of cellulose to glucose requires the cooperative action of three classes of enzymes, collectively known as cellulases. Endoglucanases randomly bind to cellulose surfaces and generate new chain ends by hydrolyzing β-1,4-D-glycosidic bonds. Exoglucanases bind to free chain ends and hydrolyze glycosidic bonds in a processive manner releasing cellobiose units. Then, β-glucosidases hydrolyze soluble cellobiose to glucose. Optimal synergistic action of these enzymes is essential for efficient digestion of cellulose. Experiments show that as hydrolysis proceeds and the cellulose substrate becomes more heterogeneous, the overall degradation slows down. As catalysis occurs on the surface of crystalline cellulose, several factors affect the overall hydrolysis. Therefore, spatial models of cellulose degradation must capture effects such as enzyme crowding and surface heterogeneity, which have been shown to lead to a reduction in hydrolysis rates. Results We present a coarse-grained stochastic model for capturing the key events associated with the enzymatic degradation of cellulose at the mesoscopic level. This functional model accounts for the mobility and action of a single cellulase enzyme as well as the synergy of multiple endo- and exo-cellulases on a cellulose surface. The quantitative description of cellulose degradation is calculated on a spatial model by including free and bound states of both endo- and exo-cellulases with explicit reactive surface terms (e.g., hydrogen bond breaking, covalent bond cleavages and corresponding reaction rates. The dynamical evolution of the system is simulated by including physical interactions between cellulases and cellulose. Conclusions Our coarse-grained model reproduces the qualitative behavior of endoglucanases and exoglucanases by accounting for the spatial heterogeneity of the cellulose surface as well as other spatial factors such as enzyme crowding. Importantly, it captures

Thermostable enzymes as biocatalysts in the biofuel industry.

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Yeoman, Carl J; Han, Yejun; Dodd, Dylan; Schroeder, Charles M; Mackie, Roderick I; Cann, Isaac K O

2010-01-01

Lignocellulose is the most abundant carbohydrate source in nature and represents an ideal renewable energy source. Thermostable enzymes that hydrolyze lignocellulose to its component sugars have significant advantages for improving the conversion rate of biomass over their mesophilic counterparts. We review here the recent literature on the development and use of thermostable enzymes for the depolymerization of lignocellulosic feedstocks for biofuel production. Furthermore, we discuss the protein structure, mechanisms of thermostability, and specific strategies that can be used to improve the thermal stability of lignocellulosic biocatalysts. Copyright 2010 Elsevier Inc. All rights reserved.

Characterization of the etiological structure and genotypically determined phenotypic resistance to carbapenems of infectious complications leading pathogens in critically ill patients

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O. A. Nazarchuk

2018-06-01

Full Text Available The aim is to investigate the genotypically determined phenotypic resistance to carbapenems of gram-negative microorganisms isolated from patients with critical states. Material and methods. Microbiological etiology of infectious complications in critically ill patients (n = 726 was investigated. In total, during the years 2011–2016, 933 clinical strains of infectious complications pathogens from patients with severe burns (n = 435 and from patients treated in intensive care units (n = 291 were isolated and identified. The sensitivity of microorganisms clinical isolates to antibiotics was investigated by means of the standard microbiological methods. In gram-negative bacteria resistant to carbapenems, a molecular genetic study of mechanisms of resistance, determined by the presence of VIM genes, was carried out using the method of real-time polymerase chain reaction. Results. Studies have shown that gram-negative microorganisms (Acinetobacter spp. – 36.3 %, P. aeruginosa – 31.7 %, Enterobacter spp. – 13.5 %, Proteus spp. – 7.9 %, E. coli – 3.8 %; K. pneumoniae – 3.6 %, etc. account for a significant part of infectious complications pathogens structure in critically ill patients. A. baumannii strains (67 % have expressed phenotypic resistance to most antibiotics, in particular to carbapenems (up to 63.2 %. Poly-antibiotic resistance was also found in P. aeruginosa (72 %, and above one the 3rd part of strains of this pathogen was found to have phenotypic resistance to carbapenems. In-depth study of molecular genetic determinants of the resistance mechanism to β-lactam antibiotics among clinical strains of gram-negative bacteria there was proved VIM-induced resistance to carbapenems in A. baumannii, P. aeruginosa, P. mirabilis. Conclusions. Enterobacteriaceae and non-fermenting gram-negative microorganisms (P. aeruginosa, P. mirabilis, A. baumannii, which are the leading causative agents of infectious complications in patients with

Carbapenem inactivation: a very affordable and highly specific method for phenotypic detection of carbapenemase-producing Pseudomonas aeruginosa isolates compared with other methods.

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Akhi, Mohammad Taghi; Khalili, Younes; Ghotaslou, Reza; Kafil, Hossein Samadi; Yousefi, Saber; Nagili, Behroz; Goli, Hamid Reza

2017-06-01

This investigation was undertaken to compare phenotypic and molecular methods for detection of carbapenemase-producing Pseudomonas aeruginosa. A total of 245 non-duplicated isolates of P. aeruginosa were collected from hospitalized patients. Disc diffusion method was used to identify carbapenem-resistant bacteria. Three phenotypic methods, including Modified Hodge Test (MHT), Modified Carba NP (MCNP) test and Carbapenem Inactivation Method (CIM) were used for investigation of carbapenemase production. In addition, polymerase chain reaction (PCR) was used to detect carbapenemase encoding genes. Of 245 P. aeruginosa isolates investigated, 121 isolates were carbapenem-resistant. Among carbapenem-resistant isolates, 40, 39 and 35 isolates exhibited positive results using MHT, MCNP test and CIM, respectively. PCR indicated the presence of carbapenemase genes in 35 of carbapenem-resistant isolates. MHT showed low sensitivity and specificity for carbapenemase detection among P. aeruginosa isolates in comparison to PCR. CIM was most affordable and highly specific than MCNP test compared with the molecular method.

Feasibility test of utilizing Saccharophagus degradans 2-40(T) as the source of crude enzyme for the saccharification of lignocellulose.

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Jung, Young Hoon; Kim, Hyun Kyung; Song, Du-Sup; Choi, In-Geol; Yang, Taek Ho; Lee, Hee Jong; Seung, Doyoung; Kim, Kyoung Heon

2014-04-01

In the conversion of lignocellulose into high-value products, including fuels and chemicals, the production of cellulase and the enzymatic hydrolysis for producing fermentable sugar are the largest contributors to the cost of production of the final products. The marine bacterium Saccharophagus degradans 2-40(T) can degrade more than ten different complex polysaccharides found in the ocean, including cellulose and xylan. Accordingly, S. degradans has been actively considered as a practical source of crude enzymes needed for the saccharification of lignocellulose to produce ethanol by others including a leading commercial company. However, the overall enzyme system of S. degradans for hydrolyzing cellulose and hemicellulose has not been quantitatively evaluated yet in comparison with commercial enzymes. In this study, the inductions and activities of cellulase and xylanase of cell-free lysate of S. degradans were investigated. The growth of S. degradans cells and the activities of cellulase and xylanase were promoted by adding 2 % of cellulose and xylan mixture (cellulose:xylan = 4:3 in mass ratio) to the aquarium salt medium supplemented with 0.2 % glucose. The specific cellulase activity of the cell-free lysate of S. degradans, as determined by the filter paper activity assay, was approximately 70 times lower than those of commercial cellulases, including Celluclast 1.5 L and Accellerase 1000. These results imply that significant improvement in the cellulase activity of S. degradans is needed for the industrial uses of S. degradans as the enzyme source.

Process for preventing discoloration in hydrolyzed ethylene-vinyl acetate copolymers by exposure to radiation

International Nuclear Information System (INIS)

Hoyt, J.M.; Koch, K.; Williams, M. Jr.

1975-01-01

A process for the hydrolysis of a solid interpolymer of an ethylenically unsaturated hydrocarbon and a vinyl ester of a 2 to 6 carbon atom aliphatic carboxylic acid to products having a low yellowness index involves contacting of the solid interpolymer with a substantially anhydrous hydrolyzing agent and subjecting at least one of said interpolymer and said hydrolyzing agent to radiation. (U.S.)

THE EFFECTIVITY TEST OF SHEEP RUMEN LIQUOR ENZYME ADDED TO PALM KERNEL MEAL ON ITS DECREASE OF CRUDE FIBER AND APPARENT DIGESTIBILITY COEFFICIENT FOR CATFISH Pangasius hypophthalmus DIET

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Wahyu Pamungkas

2011-12-01

Full Text Available Two experiments were conducted to evaluate the hydrolysis of fiber content in palm kernel meal (PKM by sheep rumen liquor enzyme and to know the apparent digestibility coefficient of hydrolyzed PKM for catfish Pangasius hypophthalmus. The first trial examined effectivity of sheep rumen liquor enzyme to decrease crude fiber content of PKM. The added volume of sheep rumen liquor enzyme was 0, 20, 40, 60, 80, and 100 mL/kg PKM and then it was incubated for 0, 12, and 24 hours. A factorial completely randomized experimental design consisted of 2 variables and triplicates were selected. The second trial was conducted to evaluate the apparent digestibility coefficients of hydrolized PKM for catfish. Apparent digestibility coefficients were determined using chromic oxide indicator added to both reference and test diets. The feed ingredients used in the trial were hydrolyzed PKM (PKMe and unhydrolyzed PKM (PKM. Ten fishes with weighing around 20 g were used in the trial and held in 80 l tanks. Feces were collected from three replicate groups of fish using a fecal collection column attached to fish rearing tank. PKM hydrolyzed with 100 mL/kg and incubated for 24 hour showed the lowest crude fiber content (6.99% among the treatments (P<0.05. Apparent digestibility coefficient of hydrolyzed PKM was 57.57% compared with unhydrolyzed PKM 15.31%. Based on the evaluation in those parameters it was concluded that sheep rumen liquor enzyme added to PKM was effective to decrease crude fiber content of PKM and improve apparent digestibility coefficient of PKM for catfish.

Emergence and outbreak of carbapenemase-producing KPC-3 Klebsiella pneumoniae in Spain, September 2009 to February 2010: control measures.

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Robustillo Rodela, A; Díaz-Agero Pérez, C; Sanchez Sagrado, T; Ruiz-Garbajosa, P; Pita López, M J; Monge, V

2012-02-16

This report describes the epidemiological features of the first outbreak caused by KPC3 carbapenemase-producing Klebsiella pneumoniae (KPC-3-KP) in Spain and how it was effectively controlled. From 16 September 2009 to the end of February 2010, seven patients infected or colonised with KPC-3-KP were detected. Stool surveillance cultures were recovered from patients, doctors, nurses, nursing assistants, cleaners and hospital porters working in the affected units. Hand swabs were taken from workers and patients’ relatives for culturing. Environmental samples were also taken. Patients infected or colonised with KPC-3-KP were placed in single rooms under contact precautions and 4% chlorhexidine soap was used for their daily hygiene. Staff attended educational seminars and workshops on hand hygiene and isolation of patients. An alcohol-based disinfectant was used for surface cleaning and disinfecting. The floor was cleaned with a disinfectant containing benzalkonium chloride and didecyldimethylammonium. All samples collected were negative for KPC-3-KP. After implementing the control measures, no further cases were reported in the affected units. All cases had comorbidities, long hospital stay and aggressive/intensive antimicrobial treatment. This study emphasises the importance of early intensification of infection control to interrupt the transmission of KPC-producing organisms.

Two cases of monomicrobial intraabdominal abscesses due to KPC - 3 Klebsiella pneumoniae ST258 clone

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Madonia Simona

2011-09-01

Full Text Available Abstract Background Knowledge of the etiology of pyogenic liver and pancreatic abscesses is an important factor in determining the success of combined surgical and antibiotic treatment. Literature shows geographical variations in the prevalence and distribution of causative organisms, and the spread of Klebsiella pneumoniae carbapenemase-producing bacteria is an emerging cause of abdominal infections. Case presentation We herein describe two cases of intra-abdominal abscesses due to monomicrobial infection by Klebsiella pneumoniae Sequence Type 258 producing K. pneumoniae carbapenemase 3 (KPC-Kp. In case 1, a 50-year-old HIV-negative Italian woman with chronic pancreatitis showed infection of a pancreatic pseudocystic lesion caused by KPC-Kp. In case 2, a 64-year-old HIV- negative Italian woman with pancreatic neoplasm and liver metastases developed a liver abscess due to KPC after surgery. Both women were admitted to our hospital but to different surgical units. The clonal relationship between the two isolates was investigated by pulsed-field gel electrophoresis (PFGE. In case 2, the patient was already colonized at admission and inter-hospital transmission of the pathogen was presumed. A long-term combination regimen of colistin with tigecycline and percutaneous drainage resulted in full recovery and clearance of the multidrug-resistant (MDR pathogen. Conclusions Timely microbiological diagnosis, the combined use of new and old antibiotics and radiological intervention appeared to be valuable in managing these serious conditions. The emergence and dissemination of MDR organisms is posing an increasing challenge for physicians to develop new therapeutic strategies and control and prevention frameworks.