Penicillin and beta-lactam allergy: epidemiology and diagnosis.

Science.gov (United States)

Macy, Eric

2014-11-01

Penicillin is the most common beta-lactam antibiotic allergy and the most common drug class allergy, reported in about 8% of individuals using health care in the USA. Only about 1% of individuals using health care in the USA have a cephalosporin allergy noted in their medical record, and other specific non-penicillin, non-cephalosporin beta-lactam allergies are even rarer. Most reported penicillin allergy is not associated with clinically significant IgE-mediated reactions after penicillin rechallenge. Un-verified penicillin allergy is a significant and growing public health problem. Clinically significant IgE-mediated penicillin allergy can be safely confirmed or refuted using skin testing with penicilloyl-poly-lysine and native penicillin G and, if skin test is negative, an oral amoxicillin challenge. Acute tolerance of an oral therapeutic dose of a penicillin class antibiotic is the current gold standard test for a lack of clinically significant IgE-mediated penicillin allergy. Cephalosporins and other non-penicillin beta-lactams are widely, safely, and appropriately used in individuals, even with confirmed penicillin allergy. There is little, if any, clinically significant immunologic cross-reactivity between penicillins and other beta-lactams. Routine cephalosporin skin testing should be restricted to research settings. It is rarely needed clinically to safely manage patients and has unclear predictive value at this time. The use of alternative cephalosporins, with different side chains, is acceptable in the setting of a specific cephalosporin allergy. Carbapenems and monobactams are also safely used in individuals with confirmed penicillin allergy. A certain predictable, but low, rate of adverse reactions will occur with all beta-lactam antibiotic use both pre- and post-beta-lactam allergy evaluations.

Collateral sensitivity between aminoglycosides and beta-lactam antibiotics depends on active proton pumps.

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Azimi, Leila; Rastegar Lari, Abdolaziz

2017-11-01

Selection inversion is the hypothesis for antibiotic resistant inhabitation in bacteria and collateral sensitivity is one of the proposed phenomena for achievement of this hypothesis. The presence of collateral sensitivity associated with the proton motivation pump between the aminoglycosides and beta-lactam group of antibiotics is one of the examples of collateral sensitivity in some studies. The aim of this study was to demonstrate that collateral sensitivity between aminoglycosides and beta-lactam antibiotics associated with proton motivation pump may not be true in all cases. In this study, 100 Pseudomonas aeruginosa were surveyed. Gentamicin and imipenem-resistant strains were confirmed by disc diffusion method and MIC. Active proton motivation pumps were screened by pumps inhibitor. Semi-quantitative Real-Time PCR assay was used to confirm gene overexpression. Seventy-six and 79 out of 100 strains were resistant to gentamicin and imipenem, respectively. Seventy-five strains were resistant to both gentamicin and imipenem. The results of proton pump inhibitor test showed the involvement of active proton motivation pump in 22 of 75 imipenem- and gentamicin-resistant strains. According to Real - Time PCR assay, mexX efflux gene was overexpressed in the majority of isolates tested. The collateral sensitivity effect cannot explain the involvement of active proton motivation pumps in both imipenem and gentamicin-resistant strains simultaneously. Active and/or inactive proton pump in gentamicin-sensitive and/or resistant strains cannot be a suitable example for explanation of collateral sensitivity between aminoglycosides and beta-lactam antibiotics. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mechanism of activity, biosynthesis and identification of beta-lactam antimicrobial drugs

Directory of Open Access Journals (Sweden)

Marija Sedak

2011-01-01

Full Text Available Antimicrobal drugs are chemotherapeutics with a wide spectrum of use in human and veterinary medicine and livestock practice. Beta-lactams are the most widespread group of antimicrobal drugs and are most often used in human and veterinary medicine in the treatment of bacterial infections due to their powerful antimicrobial activity and very low toxicity. They are divided into the groups of penicillins, cefalosporins and monobactams. Penicillins are obtained from the filtrate of the mould cultures Penicillium notatum and Penicillium chrysogenum, while cefalosporins are obtained from the filtrate of the actinomycete cultures (Cephalosporium acremonium. Research has lead to the discovery of active groups of 6-amino-penicillin acids, whose isolation has made it possible to produce semi-synthetic penicillins that have surpassed the limitations of natural penicillin G. The physico-chemical properties of the beta-lactams can be altered by substituting hydrogen in the carboxyl group of penicillins, i.e. in modifying the side chain of cefalosporin. This increases the resistance to the activity of β-lactamase and expands the spectrum of activity. Beta-lactams, in therapy concentrations, act as a bacteriocide by inhibiting the synthesis of bacterial cell walls. Penicillins are important for antibacterial chemotherapy, often in combination with other antimicrobal drugs. Cefalosporins are usually used as a replacement for penicillin in treating infections caused by gram-negative bacteria and in prophylaxis for surgery. The use of beta-lactams in animals used for food can result in the residues of these drugs in meat and meat products or milk and eggs. The introduction of antimicrobal drugs in the human body via food is particularly dangerous due to their direct toxicity or carcinogenicity, influences on the composition of the intestinal microflora, possible allergic reactions in sensitive people, and the appearance of resistance of individual pathogenic

[Influence of testing conditions on the susceptibility results of Staphylococcus cohnii to beta-lactams].

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Nowak, Tonmasz; Szewczyk, Eligia M

2006-01-01

The high occurence of coagulase-negative staphylococci among bacteria responsible for hospital infections is unquestioned. Studies on the poorly-known novobiocin-resistant, coagulase-negative Staphylococcus cohnii were undertaken. The possibilities of optimizing conditions for determination of susceptibility to beta-lactam antibiotics of this species were researched. In the case of S. cohnii the new cefoxitin test for detection of methicillin resistant strains, introduced by the National Reference Centre for Antibiotics in Poland was found as a good and of credible quality. It was also shown, that application in in vitro examination conditions stimulating the mechanisms of resistance to beta-lactam antibiotics, supplies credible results relating to their true susceptibility. The necessity of establishing individual conditions for susceptibility determination in different species of coagulase-negative staphylococci was suggested.

Activity of beta-lactam beta-lactamase inhibitor combinations against extended spectrum beta-lactamase producing enterobacteriaceae in urinary isolates

International Nuclear Information System (INIS)

Iqbal, F.I.; Farooqi, B.J.

2012-01-01

Objective: To determine the susceptibility pattern of beta-lactam beta-lactamase inhibitor combinations against extended-spectrum beta-lactamase (ESBL) producing Enterobacteriaceae in urinary isolates. Study Design: Observational study. Place and Duration of Study: Ziauddin University Hospital, Karachi, from February to October 2008. Methodology: A total of 190 consecutive non-duplicate isolates of ESBL producing Enterobacteriaceae from urine samples of in-patients were included in the study. Urinary samples from out-patients, repeat samples and non-ESBL producing isolates were excluded. Detection of ESBL was carried out by double disk diffusion technique. Antimicrobial susceptibility testing was performed using modified Kirby Bauer's disk diffusion method according to CLSI guidelines. Statistical analysis was performed by SPSS version 10. Results: Of the 190 ESBL isolates tested, 88 cases (46.31%) were sensitive and 6 cases (3.15%) were resistant to all three combinations, the rest 96 cases (50.52%) were resistant to at least one of the combinations. Susceptibility pattern of cefoperazone/sulbactam, piperacillin/tazobactam, and amoxicillin/clavulanic acid was 95.26, 92.10, and 44.31 percent respectively. Conclusion: Cefoperazone/sulbactam exhibited the best activity against ESBL producing Enterobacteriaceae followed by piperacillin/tazobactam. Hospital antibiotic policies should be reviewed periodically to reduce the usage of extended spectrum cephalosporins and replace them with beta-lactam beta-lactamase inhibitor combinations agent for treating urinary tract infections. (author)

Continuous infusion vs. bolus dosing: implications for beta-lactam antibiotics.

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Mohd Hafiz, Abdul-Aziz; Staatz, C E; Kirkpatrick, C M J; Lipman, J; Roberts, J A

2012-01-01

Beta-lactam antibiotics display time-dependant pharmacodynamics whereby constant antibiotic concentrations rather than high peak concentrations are most likely to result in effective treatment of infections caused by susceptible bacteria. Continuous administration has been suggested as an alternative strategy, to conventional intermittent dosing, to optimise beta-lactam pharmacokinetic/pharmacodynamic (PK/PD) properties. With the availability of emerging data, we elected to systematically investigate the published literature describing the comparative PK/PD and clinical outcomes of beta-lactam antibiotics administered by continuous or intermittent infusion. We found that the studies have been performed in various patient populations including critically ill, cancer and cystic fibrosis patients. Available in vitro PK/PD data conclusively support the administration of beta-lactams via continuous infusion for maximizing bacterial killing from consistent attainment of pharmacodynamic end-points. In addition, clinical outcome data supports equivalence, even with the use of a lower dose by continuous infusion. However, the present clinical data is limited with small sample sizes common with insufficient power to detect advantages in favour of either dosing strategy. With abundant positive pre-clinical data as well as document in vivo PK/PD advantages, large multi-centre trials are needed to describe whether continuous administration of beta-lactams is truly more effective than intermittent dosing.

Effects of beta-lactamases and omp mutation on susceptibility to beta-lactam antibiotics in Escherichia coli.

Science.gov (United States)

Hiraoka, M; Okamoto, R; Inoue, M; Mitsuhashi, S

1989-01-01

Four types of beta-lactamases consisting of a penicillinase type I (TEM-1), a penicillinase type II (OXA-1), a cephalosporinase of Citrobacter freundii, and a cephalosporinase of Proteus vulgaris were introduced into Escherichia coli MC4100 and its omp mutants, MH1160 (MC4100 ompR1) and MH760 (MC4100 ompR2), by transformation. Effects of the combination of the omp mutations and these beta-lactamases on the susceptibility of E. coli strains were studied with 15 beta-lactam antibiotics including cephalosporins, cephamycins, penicillins, imipenem, and aztreonam. The ompR1 mutant, MH1160, lacks OmpF and OmpC, and it showed reduced susceptibility to 11 of the 15 beta-lactam agents. The reduction in susceptibility to cefoxitin, moxalactam, and flomoxef was much greater than reduction in susceptibility to the other agents. When the ompR1 mutant produced the cephalosporinase of C. freundii, the susceptibility of the mutant to 12 of the 15 beta-lactam antibiotics decreased. The reduction in susceptibility of MH1160 to 10 of the 12 agents affected by the enzyme was two- to fourfold greater than that observed in MC4100. Such a synergistic effect was also observed with the cephalosporinase of P. vulgaris and ompR1 mutation against six cephalosporins, moxalactam, and aztreonam. Images PMID:2658786

Case Study of Intrapartum Antibiotic Prophylaxis and Subsequent Postpartum Beta-Lactam Anaphylaxis.

Science.gov (United States)

Stark, Mary Ann; Ross, Mary Frances; Kershner, Wendy; Searing, Kimberly

2015-01-01

Universal screening for maternal group B Streptococcus (GBS) in the prenatal period has led to administration of intrapartum antibiotic prophylaxis (IAP). Although IAP decreased the rate of early neonatal GBS disease, exposure of childbearing women to penicillin and other beta-lactam antibiotics has increased. Beta-lactam-induced anaphylaxis in the breastfeeding woman during the postpartum period illustrates risk factors for beta-lactam allergy and anaphylaxis. Treatment and nursing implications for this adverse reaction are suggested. © 2015 AWHONN, the Association of Women's Health, Obstetric and Neonatal Nurses.

Beta-Lactams combinations with Vancomycin provide synergy against VSSA, hVISA, and VISA.

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Tran, Kieu-Nhi; Rybak, Michael J

2018-03-19

Background: Increasing utilization of vancomycin due to the high prevalence of methicillin-resistant S. aureus (MRSA) infections has lead to the emergence of vancomycin-intermediate S. aureus (VISA) and heterogeneous VISA (hVISA). In vitro data suggest the potential for potent synergy between several beta-lactams and vancomycin. The objective of this study is to evaluate the synergy between beta-lactams and vancomycin against MRSA that is vancomycin susceptible, vancomycin susceptible Staphylococcus aureus (VSSA), hVISA, and VISA. Methods: Fifty randomly selected clinical MRSA strains with varying susceptibility to vancomycin were evaluated for vancomycin alone and vancomycin in combination with varying concentrations of cefazolin (CFZ), cefepime (FEP), ceftaroline (CPT), and nafcillin (NAF) minimum inhibitory concentration (MIC). The potential for synergy was assessed by 24h time-kills. Results: Beta-lactams reduced vancomycin MIC values against all strains (4-16 fold reduction). In time-kill studies against MRSA, CFZ, FEP, CPT, and NAF all demonstrated a similar extent of killing at 24h, and all showed synergistic activity with vancomycin against VSSA, hVISA, and VISA. Each of these combinations was also superior to any single agent against isolates of all three phenotypes, and each was bactericidal (P synergy of vancomycin against these Staphylococcus strains. Copyright © 2018 American Society for Microbiology.

Validation of the BetaStar® Advanced for Beta-lactams Test Kit for the Screening of Bulk Tank and Tanker Truck Milks for the Presence of Beta-lactam Drug Residues.

Science.gov (United States)

Denhartigh, Andrew; Reynolds, Lindsay; Palmer, Katherine; Klein, Frank; Rice, Jennifer; Rejman, John J

2018-05-18

A validation study was conducted for an immunochromatographic method (BetaStar ® Advanced for Beta-lactams) for the detection of beta-lactam residues in raw, commingled bovine milk. The assay detected amoxicillin, ampicillin, cloxacillin, penicillin, cephapirin, and ceftiofur below the U.S. Food and Drug Administration tolerance levels but above the maximum sensitivity thresholds established by the National Conference on Interstate Milk Shipments. The results of internal and independent laboratory dose-response studies employing spiked samples were in agreement. The test detected all six drugs at the approximate 90/95% sensitivity levels in milk from cows treated with each drug. Selectivity of the assay was 100%, as no false-positive results were obtained in testing 1148 control milk samples. Testing the estimated 90/95% sensitivity level for amoxicillin (8.5 ppb), ampicillin (6.9 ppb), cloxacillin (8.9 ppb), penicillin (4.2 ppb), and cephapirin (17.6 ppb), and at 100 ppb for each antibiotic, resulted in 94-100% positive tests for each of the beta-lactam drugs. The results of ruggedness experiments established the operating parameter tolerances for the assay. Cross-reactivity testing established that the assay detects other certain beta-lactam drugs, but it does not cross-react with any of 30 drugs belonging to seven different drug classes. Abnormally high bacterial or somatic cell counts in raw milk produced no assay interference.

NADPH-dependent glutamate dehydrogenase in Penicillium chrysogenum is involved in regulation of beta-lactam production

DEFF Research Database (Denmark)

Thykær, Jette; Kildegaard, Kanchana Rueksomtawin; Noorman, H.

2008-01-01

was detected in either of the Delta gdhA strains. Supplementation with glutamate restored growth but no beta-lactam production was detected for the constructed strains. Cultures with high ammonium concentrations (repressing conditions) and with proline as nitrogen source (de-repressed conditions) showed......The interactions between the ammonium assimilatory pathways and beta-lactam production were investigated by disruption of the NADPH-dependent glutamate dehydrogenase gene (gdhA) in two industrial beta-lactam-producing strains of Penicillium chrysogenum. The strains used were an adipoyl-7-ADCA...... continued beta-lactam production for the reference strains whereas the Delta gdhA strains remained non-productive under all conditions. By overexpressing the NAD-dependent glutamate dehydrogenase, the specific growth rate could be restored, but still no beta-lactam production was detected. The results...

Designing Predictive Models for Beta-Lactam Allergy Using the Drug Allergy and Hypersensitivity Database.

Science.gov (United States)

Chiriac, Anca Mirela; Wang, Youna; Schrijvers, Rik; Bousquet, Philippe Jean; Mura, Thibault; Molinari, Nicolas; Demoly, Pascal

Beta-lactam antibiotics represent the main cause of allergic reactions to drugs, inducing both immediate and nonimmediate allergies. The diagnosis is well established, usually based on skin tests and drug provocation tests, but cumbersome. To design predictive models for the diagnosis of beta-lactam allergy, based on the clinical history of patients with suspicions of allergic reactions to beta-lactams. The study included a retrospective phase, in which records of patients explored for a suspicion of beta-lactam allergy (in the Allergy Unit of the University Hospital of Montpellier between September 1996 and September 2012) were used to construct predictive models based on a logistic regression and decision tree method; a prospective phase, in which we performed an external validation of the chosen models in patients with suspicion of beta-lactam allergy recruited from 3 allergy centers (Montpellier, Nîmes, Narbonne) between March and November 2013. Data related to clinical history and allergy evaluation results were retrieved and analyzed. The retrospective and prospective phases included 1991 and 200 patients, respectively, with a different prevalence of confirmed beta-lactam allergy (23.6% vs 31%, P = .02). For the logistic regression method, performances of the models were similar in both samples: sensitivity was 51% (vs 60%), specificity 75% (vs 80%), positive predictive value 40% (vs 57%), and negative predictive value 83% (vs 82%). The decision tree method reached a sensitivity of 29.5% (vs 43.5%), specificity of 96.4% (vs 94.9%), positive predictive value of 71.6% (vs 79.4%), and negative predictive value of 81.6% (vs 81.3%). Two different independent methods using clinical history predictors were unable to accurately predict beta-lactam allergy and replace a conventional allergy evaluation for suspected beta-lactam allergy. Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Synthetic Beta-Lactam Antibiotic as a Selective Breast Cancer Cell Apoptosis Inducer: Significance in Breast Cancer Prevention and Treatment

Science.gov (United States)

2005-04-01

methylthiolated beta-lactams has been discovered that have potent activity against methicillin resistant Staphylococcus aureas . Most recently, we...2.40 (s, 3H); 13C NMR (CDCI3, 63 MHz) 6 170.4, 133.8, 131.4, 129.6, 128.9, 126.8, 86.7, 62.7, 58.9, 21.8. See References 15-20. This section is... section is directly related to Task 1 outlined in the Statement of Work, "To evaluate requirements of the C3 ring substituents of beta-lactams as a

Beta-lactam antibiotics during pregnancy: a cross-sectional comparative study Zagreb-Novi Sad.

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Erić, M; Leppée, M; Sabo, A; Culig, J

2012-01-01

During pregnancy, a number of changes occur in women's body, and some medications are safe and some are not. The aim of our study was to establish the possible correlation between use of beta-lactam antibiotics in pregnancy and occurrence of congenital malformations. The study included 893 pregnant women from Zagreb and 6099 pregnant women from Novi Sad. 527 pregnant women used beta-lactams. First part of the study (one month study) was performed at four maternity hospitals in Zagreb, Croatia. Second part were collected as a part of the study analysing the teratogenicity of drugs used in pregnancy, a longitudinal study performed in Novi Sad district. Pregnant women most frequently used antibacterial agents in the first trimester of pregnancy. They used 15 different antibacterial medications, most often beta-lactams. In Zagreb arm, out of the total number of pregnant women that used medications during pregnancy (859), 231 (26.9%) used beta-lactam antibiotics. Malformations were detected in 8 (3.5%) cases. The prevalence of malformations in newborns whose mothers did not take beta-lactam antibiotics in pregnancy (662) was 2.7% (18 newborns with malformations). In Novi Sad arm, out of the total number of pregnant women that used medications during pregnancy (2013), 296 (14.7%) used beta-lactam antibiotics. Malformations were detected in 14 (4.7%) cases. The prevalence of malformations in newborns whose mothers did not take beta-lactam antibiotics in pregnancy (5803) was 1.7% (99 newborns with malformations). The results show possible teratogenic potential even with those antibacterials which are considered safe (amoxicillin) but as those are usually minor malformations they often pass undetected. International pharmacoepidemiological studies of drug use in pregnancy could substantially contribute to the improvement of pharmacotherapy, and could be of great help in assessing the fetal risks.

CesRK, a two-component signal transduction system in Listeria monocytogenes, responds to the presence of cell wall-acting antibiotics and affects beta-lactam resistance

DEFF Research Database (Denmark)

Kallipolitis, Birgitte H; Ingmer, Hanne; Gahan, Cormac G

2003-01-01

Listeria monocytogenes is a food-borne pathogen that can cause a variety of illnesses ranging from gastroenteritis to life-threatening septicemia. The beta-lactam antibiotic ampicillin remains the drug of choice for the treatment of listeriosis. We have previously identified a response regulator...... of L. monocytogenes to tolerate ethanol and cell wall-acting antibiotics of the beta-lactam family. Furthermore, CesRK controls the expression of a putative extracellular peptide encoded by the orf2420 gene, located immediately downstream from cesRK. Inactivation of orf2420 revealed that it contributes...... to ethanol tolerance and pathogenesis in mice. Interestingly, we found that transcription of orf2420 was strongly induced by subinhibitory concentrations of various cell wall-acting antibiotics, ethanol, and lysozyme. The induction of orf2420 expression was abolished in the absence of CesRK. Our data suggest...

Point-of-care Beta-lactam Allergy Skin Testing by Antimicrobial Stewardship Programs: A Pragmatic Multicenter Prospective Evaluation.

Science.gov (United States)

Leis, Jerome A; Palmay, Lesley; Ho, Grace; Raybardhan, Sumit; Gill, Suzanne; Kan, Tiffany; Campbell, Jackie; Kiss, Alex; McCready, Janine B; Das, Pavani; Minnema, Brian; Powis, Jeff E; Walker, Sandra A N; Ferguson, Heather; Wong, Benny; Weber, Elizabeth

2017-06-01

Beta-lactam allergy skin testing (BLAST) is recommended by antimicrobial stewardship program (ASP) guidelines, yet few studies have systematically evaluated its impact when delivered at point-of-care. We conducted a pragmatic multicenter prospective evaluation of the use of point-of-care BLAST by ASPs. In staggered 3-month intervals, ASP teams at three hospitals received training by allergists to offer BLAST for eligible patients with infectious diseases receiving non-preferred beta-lactam therapy due to severity of their allergy. The primary outcome was the proportion of patients receiving the preferred beta-lactam therapy. Of 827 patients with reported beta-lactam allergy over 15-months, beta-lactam therapy was preferred among 632(76%). During baseline periods, 50% (124/246) received preferred beta-lactam therapy based on history, compared with 60% (232/386) during the intervention periods (p=0.02), which improved further to 81% (313/386) upon provision of BLAST (pcare across three hospital ASPs resulted in greater use of preferred beta-lactam therapy without increasing the risk of adverse drug reactions. Longer term studies are needed to better assess the safety and clinical impact of this ASP intervention. © 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.

Beta-lactam combination therapy for the treatment of Staphylococcus aureus and Enterococcus species bacteremia: A summary and appraisal of the evidence

Directory of Open Access Journals (Sweden)

Rachel Bartash

2017-10-01

Full Text Available Staphylococcal bacteremia and enterococcal bacteremia are prevalent in hospitalized or recently instrumented patients, and are associated with significant morbidity and mortality. They are often difficult to treat due to the pathogenicity of the organisms, poor response to antibiotics, and increasing development of multidrug resistance. Therefore, there has been increasing interest in combination therapy for the treatment of these infections. The aim of this review was to summarize and assess the evidence supporting combination beta-lactam therapy for both Staphylococcus aureus and Enterococcus species blood stream infections. Currently, there is promising in vitro data but little clinical evidence supporting combination beta-lactam therapy for this indication. Further clinical investigations are needed to elucidate the potential benefits of beta-lactam combination therapy over monotherapy for Gram-positive bacteremia, although combination therapy may be useful in refractory cases of bacteremia that do not respond to standard antibiotic therapy.

Is the addition of aminoglycosides to beta-lactams in cancer patients with febrile neutropenia needed?

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Contreras, Valeria; Sepúlveda, Sebastián; Heredia, Ana

2016-02-24

It is still controversial if the combined use of beta-lactam antibiotics and aminoglycosides has advantages over broad-spectrum beta-lactam monotherapy for the empirical treatment of cancer patients with febrile neutropenia. Searching in Epistemonikos database, which is maintained by screening 30 databases, we identified three systematic reviews including 14 pertinent randomized trials. We combined the evidence using meta-analysis and generated a summary of findings table following the GRADE approach. We concluded the combination of beta-lactam antibiotics and aminoglycosides probably does not lead to a reduced mortality in febrile neutropenic cancer patients and it might increase nephrotoxicity.

Sensor histidine kinase is a β-lactam receptor and induces resistance to β-lactam antibiotics

OpenAIRE

Li, Lu; Wang, Qiyao; Zhang, Hui; Yang, Minjun; Khan, Mazhar I.; Zhou, Xiaohui

2016-01-01

Bacteria can produce β-lactamases, enzymes that destroy β-lactam antibiotics and thereby resist these potent antibiotics that target cell wall synthesis. Production of β-lactamases is often controlled by β-lactam-induced perturbations in the cell wall. Here, we have identified a new mechanism controlling β-lactamase production. We found a signaling system in which a membrane-associated histidine kinase directly binds β-lactams, triggering the expression of a β-lactamase and resistance to β-la...

Sensor histidine kinase is a β-lactam receptor and induces resistance to β-lactam antibiotics.

Science.gov (United States)

Li, Lu; Wang, Qiyao; Zhang, Hui; Yang, Minjun; Khan, Mazhar I; Zhou, Xiaohui

2016-02-09

β-Lactams disrupt bacterial cell wall synthesis, and these agents are the most widely used antibiotics. One of the principle mechanisms by which bacteria resist the action of β-lactams is by producing β-lactamases, enzymes that degrade β-lactams. In Gram-negative bacteria, production of β-lactamases is often induced in response to the antibiotic-associated damage to the cell wall. Here, we have identified a previously unidentified mechanism that governs β-lactamase production. In the Gram-negative enteric pathogen Vibrio parahaemolyticus, we found a histidine kinase/response regulator pair (VbrK/VbrR) that controls expression of a β-lactamase. Mutants lacking either VbrK or VbrR do not produce the β-lactamase and are no longer resistant to β-lactam antibiotics. Notably, VbrK autophosphorylation is activated by β-lactam antibiotics, but not by other lactams. However, single amino acid substitutions in the putative periplasmic binding pocket of VbrK leads its phosphorylation in response to both β-lactam and other lactams, suggesting that this kinase is a β-lactam receptor that can directly detect β-lactam antibiotics instead of detecting the damage to cell wall resulting from β-lactams. In strong support of this idea, we found that purified periplasmic sensor domain of VbrK binds penicillin, and that such binding is critical for VbrK autophosphorylation and β-lactamase production. Direct recognition of β-lactam antibiotics by a histidine kinase receptor may represent an evolutionarily favorable mechanism to defend against β-lactam antibiotics.

Development of a new family of conformationally restricted peptides as potent nucleators of beta-turns. Design, synthesis, structure, and biological evaluation of a beta-lactam peptide analogue of melanostatin.

Science.gov (United States)

Palomo, Claudio; Aizpurua, Jesus M; Benito, Ana; Miranda, José Ignacio; Fratila, Raluca M; Matute, Carlos; Domercq, Maria; Gago, Federico; Martin-Santamaria, Sonsoles; Linden, Anthony

2003-12-31

Novel enantiopure (i)-(beta-lactam)-(Gly)-(i+3) peptide models, defined by the presence of a central alpha-alkyl-alpha-amino-beta-lactam ring placed as the (i+1) residue, have been synthesized in a totally stereocontrolled way by alpha-alkylation of suitable N-[bis(trimethylsilyl)methyl]-beta-lactams. The structural properties of these beta-lactam pseudopeptides have been studied by X-ray crystallography, Molecular Dynamics simulation, and NOESY-restrained NMR simulated annealing techniques, showing a strong tendency to form stable type II or type II' beta-turns either in the solid state or in highly coordinating DMSO solutions. Tetrapeptide models containing syn- or anti-alpha,beta-dialkyl-alpha-amino-beta-lactam rings have also been synthesized and their conformations analyzed, revealing that alpha-alkyl substitution is essential for beta-turn stabilization. A beta-lactam analogue of melanostatin (PLG amide) has also been prepared, characterized as a type-II beta-turn in DMSO-d6 solution, and tested by competitive binding assay as a dopaminergic D2 modulator in rat neuron cultured cells, displaying moderate agonist activity in the micromolar concentration range. On the basis of these results, a novel peptidomimetic design concept, based on the separation of constraint and recognition elements, is proposed.

Beta lactam antibiotics residues in cow's milk: comparison of efficacy of three screening tests used in Bosnia and Herzegovina.

Science.gov (United States)

Fejzic, Nihad; Begagic, Muris; Šerić-Haračić, Sabina; Smajlovic, Muhamed

2014-08-27

Beta lactam antibiotics are widely used in therapy of cattle, particularly for the treatment of mastitis.  Over 95% of residue testing in dairies in Bosnia and Herzegovina is for Beta lactams. The aim of this paper is to compare the efficacy of three most common screening tests for Beta lactam residues in cow's milk in our country. The tests used in the study are SNAP β Lactam test (Idexx), Rosa Charm β Lactam test and Inhibition MRL test. Study samples included: standardized concentrations of penicillin solution (0, 2, 3, 4, 5 and 6 ppb). In addition we tested milk samples from three equal size study groups (not receiving any antibiotic therapy, treated with Beta lactams for mastitis and treated with Beta lactams for diseases other than mastitis). Sensitivity and specificity were determined for each test, using standard penicillin concentrations with threshold value set at concentration of 4 ppb (Maximum residue level - MLR). Additionally we determined proportions of presumably false negative and false positive results for each test using results of filed samples testing. Agreement of test results for each test pair was assessed through Kappa coefficients interpreted by Landis-Koch scale. Detection level of all tests was shown to be well below MRL. This alongside with effects of natural inhibitors in milk contributed to finding of positive results in untreated and treated animals after the withholding period. Screening tests for beta lactam residues are important tools for ensuring that milk for human consumption is free from antibiotics residues.

Beta lactam antibiotics residues in cow's milk: comparison of efficacy of three screening tests used in Bosnia and Herzegovina

Directory of Open Access Journals (Sweden)

Nihad Fejzic

2014-08-01

Full Text Available Beta lactam antibiotics are widely used in therapy of cattle, particularly for the treatment of mastitis.  Over 95% of residue testing in dairies in Bosnia and Herzegovina is for Beta lactams. The aim of this paper is to compare the efficacy of three most common screening tests for Beta lactam residues in cow’s milk in our country. The tests used in the study are SNAP β Lactam test (Idexx, Rosa Charm β Lactam test and Inhibition MRL test. Study samples included: standardized concentrations of penicillin solution (0, 2, 3, 4, 5 and 6 ppb. In addition we tested milk samples from three equal size study groups (not receiving any antibiotic therapy, treated with Beta lactams for mastitis and treated with Beta lactams for diseases other than mastitis. Sensitivity and specificity were determined for each test, using standard penicillin concentrations with threshold value set at concentration of 4 ppb (Maximum residue level – MLR. Additionally we determined proportions of presumably false negative and false positive results for each test using results of filed samples testing. Agreement of test results for each test pair was assessed through Kappa coefficients interpreted by Landis-Koch scale. Detection level of all tests was shown to be well below MRL. This alongside with effects of natural inhibitors in milk contributed to finding of positive results in untreated and treated animals after the withholding period. Screening tests for beta lactam residues are important tools for ensuring that milk for human consumption is free from antibiotics residues.

Pseudomonas aeruginosa chromosomal beta-lactamase in patients with cystic fibrosis and chronic lung infection. Mechanism of antibiotic resistance and target of the humoral immune response

DEFF Research Database (Denmark)

Ciofu, Oana

2003-01-01

the development of resistance to beta-lactam antibiotics and the occurrence of high beta-lactamase producing strains and between the MIC of the beta-lactams and the levels of beta-lactamase expression. Partially derepressed mutants, characterized by high basal levels of beta-lactamase with the possibility...... of induction to even higher levels during treatment with beta-lactam antibiotics, were the most frequent phenotype found among resistant Danish P. aeruginosa CF isolates. We have also shown that the high alginate producing P. aeruginosa isolates, that characterize the chronic lung infection in CF patients......, are more susceptible to antibiotics and produce less beta-lactamase than the non-mucoid paired isolates. We propose that the non-mucoid isolates are exposed to a relatively higher antibiotic pressure than the mucoid isolates and therefore, they become easily antibiotic resistant and in consequence produce...

Lactam hydrolysis catalyzed by mononuclear metallo-beta-lactamases: A density functional study

DEFF Research Database (Denmark)

Hemmingsen, Lars Bo Stegeager; Olsen, L.; Antony, J.

2003-01-01

Two central steps in the hydrolysis of lactam antibiotics catalyzed by mononuclear metallo-beta-lactamases, formation of the tetrahedral intermediate and its breakdown by proton transfer, are studied for model systems using the density functional B3LYP method. Metallo-beta-lactamases have two metal...

A systematic review on clinical benefits of continuous administration of beta-lactam antibiotics.

Science.gov (United States)

Roberts, Jason A; Webb, Steven; Paterson, David; Ho, Kwok M; Lipman, Jeffrey

2009-06-01

The clinical benefits of extended infusion or continuous infusion of beta-lactam antibiotics remain controversial. We systematically reviewed the literature to determine whether any clinical benefits exist for administration of beta-lactam antibiotics by extended or continuous infusion. PubMed (January 1950 to November 2007), EMBASE (1966 to November 2007), and the Cochrane Controlled Trial Register were searched (updated November 2007). Randomized controlled trials (RCTs) were meta-analyzed, and observational studies were described by two unblinded reviewers. A total of 846 patients from eligible prospective randomized controlled studies were included in the meta-analysis. Two observational studies were deemed appropriate for description. A meta-analysis of prospective RCTs was undertaken using Review Manager. Among a total of 59 potentially relevant studies, 14 RCTs involving a total of 846 patients from nine countries were deemed appropriate for meta-analysis. The use of continuous infusion of a beta-lactam antibiotic was not associated with an improvement in clinical cure (n = 755 patients; odds ratio: 1.04, 95% confidence interval: 0.74-1.46, p = 0.83, I = 0%) or mortality (n = 541 patients; odds ratio: 1.00, 95% confidence interval: 0.48-2.06, p = 1.00, I = 14.8%). All RCTs except one used a higher antibiotic dose in the bolus administration group. Two observational studies, not pooled because they did not meet the a priori criteria for meta-analysis, showed that beta-lactam administration by extended or continuous infusion was associated with an improvement in clinical cure. The difference in the results between the meta-analysis results and the observational studies could be explained by the bias created by a higher dose of antibiotic in the bolus group in the RCTs and because many of the RCTs only recruited patients with a low acuity of illness. The limited data available suggest that continuous infusion of beta-lactam antibiotics leads to the same

Dissemination and genetic support of broad-spectrum beta-lactam-resistant Escherichia coli strain isolated from two Tunisian hospitals during 2004-2012.

Science.gov (United States)

Ayari, Khaoula; Bourouis, Amel; Chihi, Hela; Mahrouki, Sihem; Naas, Thierry; Belhadj, Omrane

2017-06-01

The dissemination of extended-spectrum β-lactamase (ESBL)-producing bacteria presented a great concern worldwide. Gram-negative organisms such as Escherichia coli and Klebsiella pneumoniae are the most frequently isolated pathogens responsible for nosocomial infections. The aim of this study was to investigate and to follow the emergence of resistance and the characterization of Extended-Spectrum Beta-Lactamases (ESBL) among broad-spectrum beta-lactam- Escherichia coli clinical isolates recovered from the military hospital and Habib Thameur hospital in Tunisia. A total of 113 E.coli isolates obtained during the period 2004 through 2012 showed a significant degree of multi-resistance. Among these strains, the double-disk synergy test confirmed the ESBL phenotype in 46 isolates. These included 32(70%) strains from Hospital A and 14(30%) from Hospital B. The ESBL was identified as CTX-M-15. The ESBL resistance was transferred by a 60 kb plasmid CTXM-15-producing isolates were unrelated according to the PFGE analysis and characterization of the regions surrounding the blaCTX-M-15 showed the ISEcp1 elements located in the upstream region of the bla gene and 20 of them truncated by IS26. ESBL producing E. coli strains are a serious threat in the community in Tunisia and we should take into consideration any possible spread of such epidemiological resistance.

Beta lactam antibiotics residues in cow’s milk: comparison of efficacy of three screening tests used in Bosnia and Herzegovina

Science.gov (United States)

Fejzić, Nihad; Begagić, Muris; Šerić-Haračić, Sabina; Smajlović, Muhamed

2014-01-01

Beta lactam antibiotics are widely used in therapy of cattle, particularly for the treatment of mastitis. Over 95% of residue testing in dairies in Bosnia and Herzegovina is for Beta lactams. The aim of this paper is to compare the efficacy of three most common screening tests for Beta lactam residues in cow’s milk in our country. The tests used in the study are SNAP β Lactam test (Idexx), Rosa Charm β Lactam test (Charm Sciences) and Inhibition MRL test (A&M). Study samples included: standardized concentrations of penicillin solution (0, 2, 3, 4, 5 and 6 ppb). In addition we tested milk samples from three equal size study groups (not receiving any antibiotic therapy, treated with Beta lactams for mastitis and treated with Beta lactams for diseases other than mastitis). Sensitivity and specificity were determined for each test, using standard penicillin concentrations with threshold value set at concentration of 4 ppb (Maximum residue level – MLR). Additionally we determined proportions of presumably false negative and false positive results for each test using results of filed samples testing. Agreement of test results for each test pair was assessed through Kappa coefficients interpreted by Landis-Koch scale. Detection level of all tests was shown to be well below MRL. This alongside with effects of natural inhibitors in milk contributed to finding of positive results in untreated and treated animals after the withholding period. Screening tests for beta lactam residues are important tools for ensuring that milk for human consumption is free from antibiotics residues. PMID:25172975

Resistance of Pseudomonas aeruginosa PAO to nalidixic acid and low levels of beta-lactam antibiotics: mapping of chromosomal genes.

Science.gov (United States)

Rella, M; Haas, D

1982-01-01

Resistance to high concentrations of nalidixic acid in Pseudomonas aeruginosa PAO was due to mutations in one locus designated nalA, which was mapped by transduction between hex-9001 and leu-10. The nalA mutants were cross-resistant to pipemidic acid, a nalidixic acid analog, at relatively low concentrations. Replicative DNA synthesis was resistant to both drugs in permeabilized cells of nalA mutants. A locus coding for low-level resistance to nalidixic acid, nalB, was cotransducible with pyrB, proC, and met-28. The nalB mutants were also resistant to low levels of pipemidic acid, novobiocin, and beta-lactam antibiotics (e.g., carbenicillin, azlocillin, and cefsulodin), but not to other drugs, such as gentamicin, rifampin, kanamycin, or tetracycline. In nalB mutants, DNA replication showed wild-type sensitivity to nalidixic acid, whereas carbenicillin-induced filamentation required higher drug levels than in the wild-type strain. Thus, nalB mutations appear to decrease cell permeability to some antibiotics. The sensitivity of replicative DNA synthesis to nalidixic acid and novobiocin was very similar in P. aeruginosa and Escherichia coli; by contrast, the concentrations of these drugs needed to inhibit growth of P. aeruginosa were higher than those reported for E. coli by one or two orders of magnitude. PMID:6821455

[The outpatient use of beta lactam antibiotics in Montenegro before the introduction of new reform strategy on drug market].

Science.gov (United States)

Duborija-Kovacević, Natasa

2006-01-01

The study represents the first investigation of outpatient use of beta lactam antibiotics in Montenegro carried out in accordance with internationally approved methodology (DDD/ATC). The objective of our study was to establish both the scope and overall use of beta lactam antibiotics, and to assess their compatibility with current pharmacotherapeutic guidelines and their use in developed countries. The retrospective pharmaco-epidemiological study comprised a 100%-sample of beta lactams that were used in the period prior to introduction of new reform strategy on drug market. Beta lactam antibiotics (J01C, J01D) were the most frequently applied anti-infectives for systemic use (ATC group J) in 2000 (11.3 DDD/1000 inh./day, 61%). Penicillins (J01C) were the most utilized (8.0 DDD/1000 inh./day, 71%). Cephalosporin derivatives (cephalexin and cefaclor) accounted for the remaining 29% (3.3 DDD/1000 inh./day). Aminopenicillins were prevailing among penicillins (85%). Beta lactamase sensitive penicillins were in the second place and approximately accounted for 14%. The results of our study showed that the use of beta lactam antibacterials could be estimated as partially satisfactory. There is a need to make additional efforts with a view of further rationalization.

Beta-lactamic resistance profiles in Porphyromonas, Prevotella, and Parvimonas species isolated from acute endodontic infections.

Science.gov (United States)

Montagner, Francisco; Jacinto, Rogério Castilho; Correa Signoretti, Fernanda Graziela; Scheffer de Mattos, Vanessa; Grecca, Fabiana Soares; Gomes, Brenda Paula Figueiredo de Almeida

2014-03-01

Susceptibility to beta-lactamic agents has changed among anaerobic isolates from acute endodontic infections. The aim of the present study was to determine the prevalence of the cfxA/cfxA2 gene in Prevotella spp., Porphyromonas spp., and Parviomonas micra strains and show its phenotypic expression. Root canal samples from teeth with acute endodontic infections were collected and Porphyromonas, Prevotella, and Parvimonas micra strains were isolated and microbiologically identified with conventional culture techniques. The susceptibility of the isolates was determined by the minimum inhibitory concentration of benzylpenicillin, amoxicillin, and amoxicillin + clavulanate using the E-test method (AB BIODISK, Solna, Sweden). The presence of the cfxA/cfxA2 gene was determined through primer-specific polymerase chain reaction. The nitrocefin test was used to determine the expression of the lactamase enzyme. Prevotella disiens, Prevotella oralis, Porphyromonas gingivalis, and P. micra strains were susceptible to benzylpenicillin, amoxicillin, and amoxicillin + clavulanate. The cfxA/cfxA2 gene was detected in 2 of 29 isolates (6.9%). Simultaneous detection of the cfxA/cfxA2 gene and lactamase production was observed for 1 Prevotella buccalis strain. The gene was in 1 P. micra strain but was not expressed. Three strains were positive for lactamase production, but the cfxA/cfxA2 gene was not detected through polymerase chain reaction. There is a low prevalence of the cfxA/cfxA2 gene and its expression in Porphyromonas spp., Prevotella spp., and P. micra strains isolated from acute endodontic infections. Genetic and phenotypic screening must be performed simultaneously to best describe additional mechanisms involved in lactamic resistance for strict anaerobes. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

"Click" saccharide/beta-lactam hybrids for lectin inhibition.

Science.gov (United States)

Palomo, Claudio; Aizpurua, Jesus M; Balentová, Eva; Azcune, Itxaso; Santos, J Ignacio; Jiménez-Barbero, Jesús; Cañada, Javier; Miranda, José Ignacio

2008-06-05

Hybrid glycopeptide beta-lactam mimetics designed to bind lectins or carbohydrate recognition domains in selectins have been prepared according to a "shape-modulating linker" design. This approach was implemented using the azide-alkyne "click" cycloaddition reaction, and as shown by NMR/MD experiments, binding of the resulting mimetics to Ulex Europaeus Lectin-1 (UEL-1) occurred after a "bent-to-extended" conformational change around a partially rotatable triazolylmethylene moiety.

Sensitivity and specificity of various beta-lactam antibiotics and phenotypical methods for detection of TEM, SHV and CTX-M extended-spectrum beta-lactamases.

Science.gov (United States)

Bedenic, B; Vranes, J; Mihaljevic, Lj; Tonkic, M; Sviben, M; Plecko, V; Kalenic, S

2007-04-01

The aim of this study was to compare the sensitivity and specificity of six different beta-lactam antibiotics using five phenotypical tests for detection of extended spectrum beta-lactamases (ESBLs) based on synergism of beta-lactam antibiotics and clavulanate. Experiments were performed on a set of 80 Klebsiella pneumoniae strains and 105 Escherichia coli strains with previously characterized ESBLs (SHV, TEM and CTX-M). ESBLs were detected by five different phenotypical methods: MIC (minimum inhibitory concentration) determination of beta-lactam antibiotics with and without clavulanate, double-disk synergy test (DDST), inhibitor-potentiated disk-diffusion test (IPDDT), CLSI-Clinical and Laboratory Standard Institution (former NCCLS) combined-disk-test, and modified MAST-disk-diffusion test (MAST-DD-test). Seven antibiotics were tested as indicators of ESBL production: ceftazidime, cefotaxime, ceftriaxone, aztreonam, ceftibuten, cefpodoxime and cefepime. Ceftazidime and aztreonam were the best indicators for SHV-5, SHV-12 and TEM beta-lactamases whereas cefotaxime and ceftriaxone were the most sensitive in detection of SHV-2 and CTX-M beta-lactamases in DDST, IPDDT and CLSI test. MIC determination of beta-lactam antibiotics with and without clavulanate was the most sensitive method. DDST was the least sensitive test. Double-disk synergy test, which is the most frequently used test for detection of ESBLs in routine laboratories, was the least sensitive independently of the indicator antibiotic. Since MIC determination is a very laborious and time consuming method, we would recommend the NCCLS combined disk test or IPDD test for detection of ESBLs in routine laboratories with 5 mm zone augmentation breakpoint.

Characterization of Coagulase-Negative Staphylococci and pheno-genotypic beta lactam resistance evaluation in samples from bovine Intramammary infection

Directory of Open Access Journals (Sweden)

D.A. Melo

Full Text Available ABSTRACT This study aimed to identify Coagulase-Negative Staphylococci (CoNS species isolated from bovine mastitis, through phenotypic and PCR-RFLP (Restriction Fragment Length Polymorphism-Polimerase Chain Reaction methods and to compare both techniques to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS technique. Among them, the PCR-RFLP method, using a partially conserved sequence of the groEL gene, is a promising alternative, because of its reproducibility and reliability. On the other hand, the proteomic technique MALDI-TOF MS provides an accurate and much faster diagnosis and has been increasingly employed in microbiological identification. The pheno-genotypic profiles of beta-lactam resistance were also investigated, this characterization is important, considering that the use of antimicrobials is a key element for mastitis control in dairy farms. The concordance of the phenotypic, PCR-RFLP and MALDI-TOF MS assays to identify CoNS species was 77,5% (31/40. S. chromogenes was the species most frequently isolated. Antibiotic resistance rate was relatively low, registering values of 25.5% to penicillin, 9.6% to oxacillin and 6.2% to cefoxitin. Resistance to imipenem, cephalotin and amoxicillin+clavulanate was not observed. The mecA gene and its variant were detected in 7.6% and 4,1% of the isolates respectively. The blaZ gene was found in 43.2% of the strains resistant to penicillin.

Beta- Lactam Antibiotics Stimulate Biofilm Formation in Non-Typeable Haemophilus influenzae by Up-Regulating Carbohydrate Metabolism

Science.gov (United States)

Wu, Siva; Li, Xiaojin; Gunawardana, Manjula; Maguire, Kathleen; Guerrero-Given, Debbie; Schaudinn, Christoph; Wang, Charles; Baum, Marc M.; Webster, Paul

2014-01-01

Non-typeable Haemophilus influenzae (NTHi) is a common acute otitis media pathogen, with an incidence that is increased by previous antibiotic treatment. NTHi is also an emerging causative agent of other chronic infections in humans, some linked to morbidity, and all of which impose substantial treatment costs. In this study we explore the possibility that antibiotic exposure may stimulate biofilm formation by NTHi bacteria. We discovered that sub-inhibitory concentrations of beta-lactam antibiotic (i.e., amounts that partially inhibit bacterial growth) stimulated the biofilm-forming ability of NTHi strains, an effect that was strain and antibiotic dependent. When exposed to sub-inhibitory concentrations of beta-lactam antibiotics NTHi strains produced tightly packed biofilms with decreased numbers of culturable bacteria but increased biomass. The ratio of protein per unit weight of biofilm decreased as a result of antibiotic exposure. Antibiotic-stimulated biofilms had altered ultrastructure, and genes involved in glycogen production and transporter function were up regulated in response to antibiotic exposure. Down-regulated genes were linked to multiple metabolic processes but not those involved in stress response. Antibiotic-stimulated biofilm bacteria were more resistant to a lethal dose (10 µg/mL) of cefuroxime. Our results suggest that beta-lactam antibiotic exposure may act as a signaling molecule that promotes transformation into the biofilm phenotype. Loss of viable bacteria, increase in biofilm biomass and decreased protein production coupled with a concomitant up-regulation of genes involved with glycogen production might result in a biofilm of sessile, metabolically inactive bacteria sustained by stored glycogen. These biofilms may protect surviving bacteria from subsequent antibiotic challenges, and act as a reservoir of viable bacteria once antibiotic exposure has ended. PMID:25007395

Redeploying β-Lactam Antibiotics as a Novel Antivirulence Strategy for the Treatment of Methicillin-Resistant Staphylococcus aureus Infections

Energy Technology Data Exchange (ETDEWEB)

Waters, Elaine M.; Rudkin, Justine K.; Coughlan, Simone; Clair, Geremy C.; Adkins, Joshua N.; Gore, Suzanna; Xia, Guoqing; Black, Nikki S.; Downing, Tim; O' Neill, Eoghan; Kadioglu, Aras; O' Gara, James P.

2016-11-14

Innovative approaches to the use of existing antibiotics is an important strategy in efforts to address the escalating antimicrobial resistance crisis. Here, the beta-lactam antibiotic oxacillin was shown to significantly attenuate the virulence of MRSA despite the pathogen being resistant to this drug. Oxacillin-mediated repression of the Agr quorum-sensing system and altered cell wall architecture, was associated with reduced cytolytic activity and increased susceptibility to host killing. These findings support the inclusion of -lactam antibiotics as an adjunctive anti-virulence therapy in the treatment of MRSA infections, with the potential to significantly improve patient outcomes in a safe, cost effective manner.

Properties of immobilised penicillin G Acylase in beta-lactam antibiotic synthesis

NARCIS (Netherlands)

Janssen, M.H.A.

2006-01-01

The beta-lactam antibiotics are the most important class of antibiotics used today. In the last decade the production routes of these antibiotics have shifted from chemical routes to more environmentally benign routes using the enzyme penicillin G acylase. For both practical and economical reasons

Beta- lactam antibiotics stimulate biofilm formation in non-typeable haemophilus influenzae by up-regulating carbohydrate metabolism.

Directory of Open Access Journals (Sweden)

Siva Wu

Full Text Available Non-typeable Haemophilus influenzae (NTHi is a common acute otitis media pathogen, with an incidence that is increased by previous antibiotic treatment. NTHi is also an emerging causative agent of other chronic infections in humans, some linked to morbidity, and all of which impose substantial treatment costs. In this study we explore the possibility that antibiotic exposure may stimulate biofilm formation by NTHi bacteria. We discovered that sub-inhibitory concentrations of beta-lactam antibiotic (i.e., amounts that partially inhibit bacterial growth stimulated the biofilm-forming ability of NTHi strains, an effect that was strain and antibiotic dependent. When exposed to sub-inhibitory concentrations of beta-lactam antibiotics NTHi strains produced tightly packed biofilms with decreased numbers of culturable bacteria but increased biomass. The ratio of protein per unit weight of biofilm decreased as a result of antibiotic exposure. Antibiotic-stimulated biofilms had altered ultrastructure, and genes involved in glycogen production and transporter function were up regulated in response to antibiotic exposure. Down-regulated genes were linked to multiple metabolic processes but not those involved in stress response. Antibiotic-stimulated biofilm bacteria were more resistant to a lethal dose (10 µg/mL of cefuroxime. Our results suggest that beta-lactam antibiotic exposure may act as a signaling molecule that promotes transformation into the biofilm phenotype. Loss of viable bacteria, increase in biofilm biomass and decreased protein production coupled with a concomitant up-regulation of genes involved with glycogen production might result in a biofilm of sessile, metabolically inactive bacteria sustained by stored glycogen. These biofilms may protect surviving bacteria from subsequent antibiotic challenges, and act as a reservoir of viable bacteria once antibiotic exposure has ended.

Prevalence of beta-lactamases among ampicillin-resistant Escherichia coli and Salmonella isolated from food animals in Denmark

DEFF Research Database (Denmark)

Olesen, Inger; Hasman, Henrik; Aarestrup, Frank Møller

2004-01-01

The genetic background for beta-lactamase-mediated resistance to beta-lactam antibiotics was examined by PCR and sequencing in 160 ampicillin-resistant isolates (109 Escherichia coli and 51 Salmonella) obtained from healthy and diseased food animals in Denmark. Sequencing revealed three different...... leading to increased production of the AmpC beta-lactamase were demonstrated in 11 cefoxitin-resistant or intermediate E. coli isolates. Nine of these isolates did not contain any bla(TEM) genes, whereas the remaining two did. No genes encoding SHV or extended-spectrum beta-lactamases were detected. Two...

[Antimicrobial activity of fosfomycin under various conditions against standard strains, beta-lactam resistant strains, and multidrug efflux system mutants].

Science.gov (United States)

Mikuniya, Takeshi; Hiraishi, Toru; Maebashi, Kazunori; Ida, Takashi; Takata, Toshihiko; Hikida, Muneo; Yamada, Sakuo; Gotoh, Naomasa; Nishino, Takeshi

2005-04-01

The purpose of this study was to evaluate the possible benefit of fosfomycin (FOM) as prophylactic antibiotic in terms of antimicrobial activity and the potential of inducibility of beta-lactamase, compared with cefazolin, cefotiam, cefmetazole, and piperacillin that are commonly used as perioperative agents. The in vitro activity of FOM against aerobic Gram-negative bacteria using Mueller-Hinton agar or nutrient agar supplemented with glucose-6-phosphate (G6P) as tested medium increased within a range from 2 to 256 times the activity in the medium without G6P. However, the susceptibility of Gram-positive bacteria to FOM remained largely unchanged with or without G6P. There was no aerobic- or anaerobic-bacteria which changed susceptibility against beta-lactam antibiotics under various tested medium conditions. FOM demonstrated strong bactericidal activity against Escherichia coli and Pseudomonas aeruginosa in a dose dependent manner, and decreased viable cell counts of Staphylococcus aureus. In the case of P. aeruginosa, transmission electron micrographs study revealed that numerous lysed cells were present 2 hours after treatment with FOM at four times the MIC. First and second generation cephalosporins induced AmpC-type beta-lactamase in a dose dependent manner among beta-lactamase inducible strains of P. aeruginosa and Enterobacter cloacae. On the other hand, inducible activity of FOM on beta-lactamase production was less than 1/25 to 1/65 compared with those of cephalosporins. In addition, FOM maintained strong antimicrobial activity for over then 20 years after marketing, because of the excellent stability against various types of beta-lactamase produced by plasmid-carrying bacteria and clinical isolates. FOM was not extruded by four types of efflux systems, such as MexAB-OprM, MexCD-OprJ, MexXY/ OprM and MexEF-OprN, however beta-lactam antibiotics were substrates of MexAB-OprM and MexCD-OprJ. In conclusion, FOM provides adequate coverage for both aerobic Gram

Abundances of tetracycline, sulphonamide and beta-lactam antibiotic resistance genes in conventional wastewater treatment plants (WWTPs with different waste load.

Directory of Open Access Journals (Sweden)

Mailis Laht

Full Text Available Antibiotics and antibiotic resistant bacteria enter wastewater treatment plants (WWTPs, an environment where resistance genes can potentially spread and exchange between microbes. Several antibiotic resistance genes (ARGs were quantified using qPCR in three WWTPs of decreasing capacity located in Helsinki, Tallinn, and Tartu, respectively: sulphonamide resistance genes (sul1 and sul2, tetracycline resistance genes (tetM and tetC, and resistance genes for extended spectrum beta-lactams (blaoxa-58, blashv-34, and blactx-m-32. To avoid inconsistencies among qPCR assays we normalised the ARG abundances with 16S rRNA gene abundances while assessing if the respective genes increased or decreased during treatment. ARGs were detected in most samples; sul1, sul2, and tetM were detected in all samples. Statistically significant differences (adjusted p<0.01 between the inflow and effluent were detected in only four cases. Effluent values for blaoxa-58 and tetC decreased in the two larger plants while tetM decreased in the medium-sized plant. Only blashv-34 increased in the effluent from the medium-sized plant. In all other cases the purification process caused no significant change in the relative abundance of resistance genes, while the raw abundances fell by several orders of magnitude. Standard water quality variables (biological oxygen demand, total phosphorus and nitrogen, etc. were weakly related or unrelated to the relative abundance of resistance genes. Based on our results we conclude that there is neither considerable enrichment nor purification of antibiotic resistance genes in studied conventional WWTPs.

The order of administration of macrolides and beta-lactams may impact the outcomes of hospitalized patients with community-acquired pneumonia: results from the community-acquired pneumonia organization.

Science.gov (United States)

Peyrani, Paula; Wiemken, Timothy L; Metersky, Mark L; Arnold, Forest W; Mattingly, William A; Feldman, Charles; Cavallazzi, Rodrigo; Fernandez-Botran, Rafael; Bordon, Jose; Ramirez, Julio A

2018-01-01

The beneficial effect of macrolides for the treatment of community-acquired pneumonia (CAP) in combination with beta-lactams may be due to their anti-inflammatory activity. In patients with pneumococcal meningitis, the use of steroids improves outcomes only if they are administered before beta-lactams. The objective of this study was to compare outcomes in hospitalized patients with CAP when macrolides were administered before, simultaneously with, or after beta-lactams. Secondary data analysis of the Community-Acquired Pneumonia Organization (CAPO) International Cohort Study database. Study groups were defined based on the sequence of administration of macrolides and beta-lactams. The study outcomes were time to clinical stability (TCS), length of stay (LOS) and in-hospital mortality. Accelerated failure time models were used to evaluate the adjusted impact of sequential antibiotic administration and time-to-event outcomes, while a logistic regression model was used to evaluate their adjusted impact on mortality. A total of 99 patients were included in the macrolide before group and 305 in the macrolide after group. Administration of a macrolide before a beta-lactam compared to after a beta-lactam reduced TCS (3 vs. 4 days, p = .011), LOS (6 vs. 7 days, p = .002) and mortality (3 vs. 7.2%, p = .228). The administration of macrolides before beta-lactams was associated with a statistically significant decrease in TCS and LOS and a non-statistically significant decrease in mortality. The beneficial effect of macrolides in hospitalized patient with CAP may occur only if administered before beta-lactams.

Novel Ambler class A beta-lactamase LAP-1 and its association with the plasmid-mediated quinolone resistance determinant QnrS1.

Science.gov (United States)

Poirel, Laurent; Cattoir, Vincent; Soares, Ana; Soussy, Claude-James; Nordmann, Patrice

2007-02-01

The plasmid-mediated quinolone resistance determinant QnrS1 was identified in non-clonally related Enterobacter cloacae isolates in association with a transferable narrow-spectrum beta-lactam resistance marker. Cloning experiments allowed the identification of a novel Ambler class A beta-lactamase, named LAP-1. It shares 62 and 61% amino acid identity with the most closely related beta-lactamases, TEM-1 and SHV-1, respectively. It has a narrow-spectrum hydrolysis of beta-lactams and is strongly inhibited by clavulanic acid and sulbactam and, to a lesser extent, by tazobactam. Association of the blaLAP-1 gene with the qnrS1 gene was identified in E. cloacae isolates from France and Vietnam. These genes were plasmid located and associated with similar insertion sequences but were not associated with sul1-type class 1 integrons, as opposed to the qnrA genes.

Analysis of profitability in the diagnosis of allergy to beta-lactam antibiotics.

Science.gov (United States)

Ferré-Ybarz, L; Salinas Argente, R; Gómez Galán, C; Duocastella Selvas, P; Nevot Falcó, S

2015-01-01

Drug allergy is the third most common reason for allergy consultations. There is a tendency to call any adverse drug reaction (ADR) allergic, even without confirmatory allergy study. (1) Evaluate time of resolution allergy to beta-lactam's study in a sample of 100 patients. (2) Analyse cost-effectiveness of current diagnostic study (skin tests, specific IgE and drug provocation test (DPT)). (3) Describe type and frequency of ADRs in adult/paediatric patients. (4) Compare cost of complete study with DPT. (5) Assess the need to restructure current study methodology according to results obtained. The study is part of a strategic plan of the allergy department (2005-2010). Patients with suspected allergy to beta-lactams were included. Procedures performed: medical history, specific IgE, skin tests and DPT. Cost/patient analysis. Cost of protocol analysis for current diagnostic/direct DPT. 100 patients were studied, 52 females/48 males; 43 children/57 adults. 89 cutaneous, 4 anaphylaxis, 3 vasovagal reactions, 6 non-specific symptoms and 4 not recalled. Allergy was confirmed in six patients (only one child). Complete-study cost: 149.3 Euros/patient. DPT-study cost: 97.19 Euros/patient (34.9% less). Resolution time 9-13 months, absenteeism 28.04%. In the series studied, diagnosis of allergy to beta-lactams was confirmed in 6% of patients (2.3% of paediatric patients). After analysing results and cost of the study we believe that we should propose a specific diagnostic algorithm in those paediatric patients without suspected IgE-mediated ADR, and for those patients direct DPT should be conducted. This will reduce cost/patient (-34.9%), time of resolution and absenteeism. Copyright © 2014 SEICAP. Published by Elsevier Espana. All rights reserved.

Zinc Finger Nuclease: A New Approach to Overcome Beta-Lactam Antibiotic Resistance

Science.gov (United States)

Shahbazi Dastjerdeh, Mansoureh; Kouhpayeh, Shirin; Sabzehei, Faezeh; Khanahmad, Hossein; Salehi, Mansour; Mohammadi, Zahra; Shariati, Laleh; Hejazi, Zahra; Rabiei, Parisa; Manian, Mostafa

2016-01-01

Background: The evolution of antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs) has been accelerated recently by the indiscriminate application of antibiotics. Antibiotic resistance has challenged the success of medical interventions and therefore is considered a hazardous threat to human health. Objectives: The present study aimed to describe the use of zinc finger nuclease (ZFN) technology to target and disrupt a plasmid-encoded β-lactamase, which prevents horizontal gene transfer-mediated evolution of ARBs. Materials and Methods: An engineered ZFN was designed to target a specific sequence in the ampicillin resistance gene (ampR) of the pTZ57R plasmid. The Escherichia coli bacteria already contained the pZFN kanamycin-resistant (kanaR) plasmid as the case or the pP15A, kanaR empty vector as the control, were transformed with the pTZ57R; the ability of the designed ZFN to disrupt the β-lactamase gene was evaluated with the subsequent disturbed ability of the bacteria to grow on ampicillin (amp) and ampicillin-kanamycin (amp-kana)-containing media. The effect of mild hypothermia on the ZFN gene targeting efficiency was also evaluated. Results: The growth of bacteria in the case group on the amp and amp-kana-containing media was significantly lower compared with the control group at 37°C (P < 0.001). Despite being more efficient in hypothermic conditions at 30°C (P < 0.001), there were no significant associations between the incubation temperature and the ZFN gene targeting efficiency. Conclusions: Our findings revealed that the ZFN technology could be employed to overcome ampicillin resistance by the targeted disruption of the ampicillin resistance gene, which leads to inactivation of β-lactam synthesis. Therefore, ZFN technology could be engaged to decrease the antibiotic resistance issue with the construction of a ZFN archive against different ARGs. To tackle the resistance issue at the environmental level, recombinant phages

Saturation mutagenesis reveals the importance of residues alpha R145 and alpha F146 of penicillin acylase in the synthesis of beta-lactam antibiotics

NARCIS (Netherlands)

Jager, Simon A. W.; Shapovalova, Irina V.; Jekel, Peter A.; Alkema, Wynand B. L.; Svedas, Vytas K.; Janssen, Dick B.; Švedas, Vytas K.

2008-01-01

Penicillin acylase (PA) from Escherichia coli can catalyze the coupling of an acyl group to penicillin- and cephalosporin-derived beta-lactam nuclei, a conversion that can be used for the industrial synthesis of beta-lactam. antibiotics. The modest synthetic properties of the wild-type enzyme make

Trans-Cinnamaldehyde and Eugenol Increase Acinetobacter baumannii Sensitivity to Beta-Lactam Antibiotics

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Deepti P. Karumathil

2018-05-01

Full Text Available Multi-drug resistant (MDR Acinetobacter baumannii is a major nosocomial pathogen causing a wide range of clinical conditions with significant mortality rates. A. baumannii strains are equipped with a multitude of antibiotic resistance mechanisms, rendering them resistant to most of the currently available antibiotics. Thus, there is a critical need to explore novel strategies for controlling antibiotic resistance in A. baumannii. This study investigated the efficacy of two food-grade, plant-derived antimicrobials (PDAs, namely trans-cinnamaldehyde (TC and eugenol (EG in decreasing A. baumannii’s resistance to seven β-lactam antibiotics, including ampicillin, methicillin, meropenem, penicillin, aztreonam, amoxicillin, and piperacillin. Two MDR A. baumannii isolates (ATCC 17978 and AB 251847 were separately cultured in tryptic soy broth (∼6 log CFU/ml containing the minimum inhibitory concentration (MIC of TC or EG with or without the MIC of each antibiotic at 37°C for 18 h. A. baumannii strains not exposed to the PDAs or antibiotics served as controls. Following incubation, A. baumannii counts were determined by broth dilution assay. In addition, the effect of PDAs on the permeability of outer membrane and efflux pumps in A. baumannii was measured. Further, the effect of TC and EG on the expression of A. baumannii genes encoding resistance to β-lactam antibiotics (blaP, efflux pumps (adeABC, and multi-drug resistant protein (mdrp was studied using real-time quantitative PCR (RT-qPCR. The experiment was replicated three times with duplicate samples of each treatment and control. The results from broth dilution assay indicated that both TC and EG in combination with antibiotics increased the sensitivity of A. baumannii to all the tested antibiotics (P < 0.05. The two PDAs inhibited the function of A. baumannii efflux pump, (AdeABC, but did not increase the permeability of its outer membrane. Moreover, RT-qPCR data revealed that TC and EG

Trans-Cinnamaldehyde and Eugenol Increase Acinetobacter baumannii Sensitivity to Beta-Lactam Antibiotics.

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Karumathil, Deepti P; Nair, Meera Surendran; Gaffney, James; Kollanoor-Johny, Anup; Venkitanarayanan, Kumar

2018-01-01

Multi-drug resistant (MDR) Acinetobacter baumannii is a major nosocomial pathogen causing a wide range of clinical conditions with significant mortality rates. A. baumannii strains are equipped with a multitude of antibiotic resistance mechanisms, rendering them resistant to most of the currently available antibiotics. Thus, there is a critical need to explore novel strategies for controlling antibiotic resistance in A. baumannii . This study investigated the efficacy of two food-grade, plant-derived antimicrobials (PDAs), namely trans -cinnamaldehyde (TC) and eugenol (EG) in decreasing A. baumannii 's resistance to seven β-lactam antibiotics, including ampicillin, methicillin, meropenem, penicillin, aztreonam, amoxicillin, and piperacillin. Two MDR A. baumannii isolates (ATCC 17978 and AB 251847) were separately cultured in tryptic soy broth (∼6 log CFU/ml) containing the minimum inhibitory concentration (MIC) of TC or EG with or without the MIC of each antibiotic at 37°C for 18 h. A. baumannii strains not exposed to the PDAs or antibiotics served as controls. Following incubation, A. baumannii counts were determined by broth dilution assay. In addition, the effect of PDAs on the permeability of outer membrane and efflux pumps in A. baumannii was measured. Further, the effect of TC and EG on the expression of A. baumannii genes encoding resistance to β-lactam antibiotics ( blaP ), efflux pumps ( adeABC ), and multi-drug resistant protein ( mdrp ) was studied using real-time quantitative PCR (RT-qPCR). The experiment was replicated three times with duplicate samples of each treatment and control. The results from broth dilution assay indicated that both TC and EG in combination with antibiotics increased the sensitivity of A. baumannii to all the tested antibiotics ( P increase the permeability of its outer membrane. Moreover, RT-qPCR data revealed that TC and EG down-regulated the expression of majority of the genes associated with β-lactam antibiotic

Antimicrobial Effects of β-Lactams on Imipenem-Resistant Ceftazidime-Susceptible Pseudomonas aeruginosa.

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Wi, Yu Mi; Choi, Ji-Young; Lee, Ji-Young; Kang, Cheol-In; Chung, Doo Ryeon; Peck, Kyong Ran; Song, Jae-Hoon; Ko, Kwan Soo

2017-06-01

We studied the resistance mechanism and antimicrobial effects of β-lactams on imipenem-resistant Pseudomonas aeruginosa isolates that were susceptible to ceftazidime as detected by time-kill curve methods. Among 215 P. aeruginosa isolates from hospitalized patients in eight hospitals in the Republic of Korea, 18 isolates (23.4% of 77 imipenem-resistant isolates) were imipenem resistant and ceftazidime susceptible. Multilocus sequence typing revealed diverse genotypes, which indicated independent emergence. These 18 isolates were negative for carbapenemase genes. All 18 imipenem-resistant ceftazidime-susceptible isolates showed decreased mRNA expression of oprD , and overexpression of mexB was observed in 13 isolates. In contrast, overexpression of ampC , mexD , mexF , or mexY was rarely found. Time-kill curve methods were applied to three selected imipenem-resistant ceftazidime-susceptible isolates at a standard inoculum (5 × 10 5 CFU/ml) or at a high inoculum (5 × 10 7 CFU/ml) to evaluate the antimicrobial effects of β-lactams. Inoculum effects were detected for all three β-lactam antibiotics, ceftazidime, cefepime, and piperacillin-tazobactam, against all three isolates. The antibiotics had significant killing effects in the standard inoculum, but no effects in the high inoculum were observed. Our results suggest that β-lactam antibiotics should be used with caution in patients with imipenem-resistant ceftazidime-susceptible P. aeruginosa infection, especially in high-inoculum infections such as endocarditis and osteomyelitis. Copyright © 2017 American Society for Microbiology.

In Silico Assigned Resistance Genes Confer Bifidobacterium with Partial Resistance to Aminoglycosides but Not to Β-Lactams

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Fouhy, Fiona; O’Connell Motherway, Mary; Fitzgerald, Gerald F.; Ross, R. Paul; Stanton, Catherine; van Sinderen, Douwe; Cotter, Paul D.

2013-01-01

Bifidobacteria have received significant attention due to their contribution to human gut health and the use of specific strains as probiotics. It is thus not surprising that there has also been significant interest with respect to their antibiotic resistance profile. Numerous culture-based studies have demonstrated that bifidobacteria are resistant to the majority of aminoglycosides, but are sensitive to β-lactams. However, limited research exists with respect to the genetic basis for the resistance of bifidobacteria to aminoglycosides. Here we performed an in-depth in silico analysis of putative Bifidobacterium-encoded aminoglycoside resistance proteins and β-lactamases and assess the contribution of these proteins to antibiotic resistance. The in silico-based screen detected putative aminoglycoside and β-lactam resistance proteins across the Bifidobacterium genus. Laboratory-based investigations of a number of representative bifidobacteria strains confirmed that despite containing putative β-lactamases, these strains were sensitive to β-lactams. In contrast, all strains were resistant to the aminoglycosides tested. To assess the contribution of genes encoding putative aminoglycoside resistance proteins in Bifidobacterium sp. two genes, namely Bbr_0651 and Bbr_1586, were targeted for insertional inactivation in B. breve UCC2003. As compared to the wild-type, the UCC2003 insertion mutant strains exhibited decreased resistance to gentamycin, kanamycin and streptomycin. This study highlights the associated risks of relying on the in silico assignment of gene function. Although several putative β-lactam resistance proteins are located in bifidobacteria, their presence does not coincide with resistance to these antibiotics. In contrast however, this approach has resulted in the identification of two loci that contribute to the aminoglycoside resistance of B. breve UCC2003 and, potentially, many other bifidobacteria. PMID:24324818

In silico assigned resistance genes confer Bifidobacterium with partial resistance to aminoglycosides but not to β-lactams.

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Fiona Fouhy

Full Text Available Bifidobacteria have received significant attention due to their contribution to human gut health and the use of specific strains as probiotics. It is thus not surprising that there has also been significant interest with respect to their antibiotic resistance profile. Numerous culture-based studies have demonstrated that bifidobacteria are resistant to the majority of aminoglycosides, but are sensitive to β-lactams. However, limited research exists with respect to the genetic basis for the resistance of bifidobacteria to aminoglycosides. Here we performed an in-depth in silico analysis of putative Bifidobacterium-encoded aminoglycoside resistance proteins and β-lactamases and assess the contribution of these proteins to antibiotic resistance. The in silico-based screen detected putative aminoglycoside and β-lactam resistance proteins across the Bifidobacterium genus. Laboratory-based investigations of a number of representative bifidobacteria strains confirmed that despite containing putative β-lactamases, these strains were sensitive to β-lactams. In contrast, all strains were resistant to the aminoglycosides tested. To assess the contribution of genes encoding putative aminoglycoside resistance proteins in Bifidobacterium sp. two genes, namely Bbr_0651 and Bbr_1586, were targeted for insertional inactivation in B. breve UCC2003. As compared to the wild-type, the UCC2003 insertion mutant strains exhibited decreased resistance to gentamycin, kanamycin and streptomycin. This study highlights the associated risks of relying on the in silico assignment of gene function. Although several putative β-lactam resistance proteins are located in bifidobacteria, their presence does not coincide with resistance to these antibiotics. In contrast however, this approach has resulted in the identification of two loci that contribute to the aminoglycoside resistance of B. breve UCC2003 and, potentially, many other bifidobacteria.

An investigation of resistance to β-lactam antimicrobials among staphylococci isolated from pigs with exudative epidermitis.

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Park, Jeonghwa; Friendship, Robert M; Weese, J Scott; Poljak, Zvonimir; Dewey, Cate E

2013-10-17

A high proportion of staphylococci isolated from pigs affected with exudative epidermitis were found to be resistant to β-lactam antimicrobials. The primary objective of this research was to investigate and characterize β-lactam resistance in Staphylococcus hyicus, Staphylococcus aureus and other staphylococci isolated from these pigs. The antimicrobial resistance patterns of 240 staphylococci isolates were determined by disk diffusion, of which 176 (73.3%) of the isolates were resistant to 3 β-lactams (penicillin G, ampicillin, and ceftiofur). The presence of mecA gene was identified in 63 staphylococci isolates from skin samples by PCR. The mecA gene was identified in 19 S. aureus, 31 S. hyicus, 9 Staphylococcus chromogenes, 2 Staphylococcus pseudintermedius isolates, and in 1 isolate each of Staphylococcus arlettae, and Staphylococcus cohnii subspecies urealyticus. From SCCmec typing results, the majority (45/63, 71.4%) were shown to be SCCmec type V. One isolate was SCCmec III. Fourteen isolates were detected as mec class A, mec class C or ccr type 5. The ccr complex and mec complex was not detected in 3 isolates of methicillin resistant S. hyicus (MRSH) based on multiplex PCR. Of the 30 isolates of MRSA identified from nasal samples of the pigs, 29 isolates were SCCmec type V and 1 isolate was SCCmec type II. Staphyloccoci isolates that were mecA negative but resistant to β-lactam antimicrobials were further examined by screening for mecC, however all were negative. Furthermore, the majority of mecA negative β-lactam resistant staphylococci isolates were susceptible to oxacillin and amoxicillin-clavulanic acid in a double disk diffusion test. Methicillin resistance can be identified in a variety of staphylococcal species isolated from pigs. In this study there was a great deal of similarity in the SCCmec types between staphylococcal species, suggesting that resistance may be passed from one species of staphylococci to another species of staphylococci

Prevalence of quinolone resistance determinant qnrA6 among broad- and extended-spectrum beta-lactam-resistant Proteus mirabilis and Morganella morganii clinical isolates with sul1-type class 1 integron association in a Tunisian Hospital.

Science.gov (United States)

Mahrouki, Sihem; Perilli, Mariagrazia; Bourouis, Amel; Chihi, Hela; Ferjani, Mustapha; Ben Moussa, Mohamed; Amicosante, Gianfranco; Belhadj, Omrane

2013-08-01

The aim of this study was to investigate the prevalence and the emergence of plasmid-mediated quinolone resistance among broad-spectrum beta-lactam-resistant Proteus mirabilis and Morganella morganii clinical isolates recovered in the Military Hospital in Tunisia. Of 200 strains examined, 50 exhibited resistance to quinolones. Quinolone resistance determinants (qnr and aac(6')-Ib-cr) were characterized by multiplex PCR and sequencing. Chromosomal quinolone resistance mutations in the quinolone resistance-determining region (QRDR) and class 1 integron characterization were analysed by PCR and sequencing. The clonal relationship between the isolates was studied by pulsed-field gel electrophoresis (PFGE). Fourteen isolates harboured qnrA6 and among them 8 (57%) were extended-spectrum beta-lactamase (ESBL) producers, whilst 12 (85%) isolates harboured blaDHA-1. Mutations in the QRDR were detected in gyrA (Ser83Ile, Glu87Lys), gyrB (Ser464Phe), and parC (Ser80Ile). qnrA6 and blaDHA-1 genes were found embedded in complex sul1-type class 1 integrons. A gene cassette carrying aac(6')-Ib-cr was found located in the class 1 integron upstream of the qacEΔ1 gene. According to the PFGE analysis, the isolates were clonally unrelated. This is the first description in North Africa of class 1 integrons carrying blaDHA-1, qnrA6 gene, and aac(6')-Ib-cr determinants in clinical strains of Proteus mirabilis and Morganella morganii.

Detection of Beta-lactamase gene in the culturable bacteria isolated from agricultural, pasture and mining soils around mines in Hamedan, Iran

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Nayereh Younessi

2017-09-01

Full Text Available Introduction: Growing evidence exists that agriculture affects antibiotic resistance in human pathogens. Beta-lactam antibiotics are the most commonly used antimicrobial agents in many countries. The abundance of beta-lactamase encoding genes can be used as an indicator of antibiotic resistance in the environment. So, to determine the beta-lactamase resistance genes, the abundance of culturable bacteria having bla-TEM genesin the soils under different land uses wasexamined. Materials and methods: 44 Gram-positive and 34 Gram-negative bacteria plated on nutrient agar were isolated from agricultural, pasture and mining soils and selected to study the presence of TEM-class gene using PCR amplification. Antibiotic sensitivity test of bla-TEM+isolateswas done adopting the Kirby-Bauer disk diffusion method and antibiotic discs used were: ampicillin, amoxicillin, vancomicin, streptomycin, tetracycline and gentamicin. Finally, five multi-drug resistant and bla-TEM+ isolates were identified using universal primers. Results: The highest level of beta-lactamase genes was observed in the Gram-positive and Gram-negative isolates from the pasture soils. In the agricultural and mining soils, a high abundance of bla-TEM+ isolateswasfound which also showed resistance to beta-lactam antibiotics. The identified multi-drug resistant and bla-TEM+ isolates were from these genera: Achromobacter, Bacillus, Brevibacillus, Aminobacter and Brevundimonas. Discussion and conclusion: The high number of bla-TEM+ bacteria in all the soils may be attributed to the other important feature of bla genes which is their capability to extrude toxic compounds like heavy metals in contaminated environments. Sensitivity of some bla-TEM+ bacteria to beta-lactam antibiotics was interesting. This result shows that bla-TEM genes confer resistance to beta-lactamase inhibitors in a different degree. Some of the identified isolates were pathogen. These pathogens in soils can transfer to plants

The effect of mutations in the AmpC promoter region on β-lactam ...

African Journals Online (AJOL)

STORAGESEVER

2008-08-04

Aug 4, 2008 ... between the -10 and -35 boxes affects the resistance of bacteria to β-lactam antibiotics. .... The chromosomal cephalosporinase gene, ampC, of E. .... mutation in the ampC promoter increasing resistance to β-lactams in.

Emergence of colistin resistance in extended-spectrum beta lactamase producing Enterobacteriaceae isolated from food animals and its public health implication: A review

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Asinamai Athliamai Bitrus

2018-03-01

Full Text Available Antimicrobial resistance as a result of emergence of extended-spectrum beta lactamase producing Enterobacteriaceae is a major health problem of human and animal that requires an intensive global attention. The production of beta lactamase enzymes remains as one of the major factors contributing to the development of resistance to beta lactams. These enzymes hydrolyze the beta lactam ring of the antibiotic and render it ineffective. Extended-spectrum beta lactamase producing bacteria have the ability to develop resistance to a number of antibiotics including the carbapenem and other third generation cephalosporins. In addition, the recent emergence and dissemination of the colistin resistance determinants mcr-1, mcr-2 and mcr-3 poses a serious threat to colistin as a drug of last resort in human medicine. In this review, we utilized words such as “colistin resistance and Escherichia coli”, “Klebsiella and colistin resistance”, “colistin resistance and Salmonella” as well as “detection of mcr-1 genes in Salmonella and E. coli”. The extended-spectrum beta lactamase producing bacteria under Enterobacteriaceae that are resistant to colistin possess the ability to be transferred resistant determinants to other susceptible cells at a higher frequency. In this paper, the role of manure from food animals and how air travel contributes to the dissemination of mcr-1 haboring bacteria, resistance determinants and other metabolites that constitute a public health problem was also reviewed. It is concluded that these pathogens have significant consequences to the control of infection and plays key roles in treatment failure with colistin. [J Adv Vet Anim Res 2018; 5(1.000: 1-11

Evaluation of sensitivity of modified star protocol microbiological method for beta-lactame antibiotics detection in raw cow milk

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Borović Branka

2013-01-01

Full Text Available Antibiotic residues when present in animal tissues, through food chain, can enter human body, causing allergic reactions or facilitating the development of resistant bacterial strains. In order to determine the presence of antibiotics in animal tissues, it is appropriate to use convenient, reliable and sensitive methods. Microbiological methods applied for the detection of antibiotic residues in primary products of animal origin are based on the sensitivity of specific bacterial strains to a particular group of antibiotics. Regulatives on the amount of pesticides, metals and metalloids and other toxic substances, chemotherapeutics, anabolics and other substances which can be found in food ("Off. Gazette", No. 5/92, 11/92 - corr. and 32/02, state that milk and milk products can be used in commercial purposes only if not contain antibiotics in quantities that can be detected by reference methods. The applied method is modified STAR (Screening test for detection of antibiotics protocol, regulated by the CRL (Community Reference Laboratory Fougeres, France, in which the initial validation of the method had been carried out. In accordance with the demands of Regulative Commission EC No657/2002, the sensitivity of modified STAR protocol for beta lactam antibiotics group was examined , that is, there was carried out a contracted validation of the method, which initial validation had been performed at CRL. In a couple of series of experiments, 20 blank samples of raw cow milk originating from animals not treated by antibiotics, had been examined. By the beginning of the experiment samples were stored in a freezer at -20ºC. Samples of raw cow milk enriched by working solutions of seven beta-lactam antibiotics, in order to obtain concentrations at the level of 0.5, 1 and 1.5 MRL (Maximmum Residue Limit for each given antibiotic (Commission Regulation EC No. 37/2010. For detection of beta-lactam antibiotics, there was used Kundrat agar test with

Penicillin-Binding Protein Transpeptidase Signatures for Tracking and Predicting β-Lactam Resistance Levels in Streptococcus pneumoniae

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Yuan Li

2016-06-01

Full Text Available β-Lactam antibiotics are the drugs of choice to treat pneumococcal infections. The spread of β-lactam-resistant pneumococci is a major concern in choosing an effective therapy for patients. Systematically tracking β-lactam resistance could benefit disease surveillance. Here we developed a classification system in which a pneumococcal isolate is assigned to a “PBP type” based on sequence signatures in the transpeptidase domains (TPDs of the three critical penicillin-binding proteins (PBPs, PBP1a, PBP2b, and PBP2x. We identified 307 unique PBP types from 2,528 invasive pneumococcal isolates, which had known MICs to six β-lactams based on broth microdilution. We found that increased β-lactam MICs strongly correlated with PBP types containing divergent TPD sequences. The PBP type explained 94 to 99% of variation in MICs both before and after accounting for genomic backgrounds defined by multilocus sequence typing, indicating that genomic backgrounds made little independent contribution to β-lactam MICs at the population level. We further developed and evaluated predictive models of MICs based on PBP type. Compared to microdilution MICs, MICs predicted by PBP type showed essential agreement (MICs agree within 1 dilution of >98%, category agreement (interpretive results agree of >94%, a major discrepancy (sensitive isolate predicted as resistant rate of <3%, and a very major discrepancy (resistant isolate predicted as sensitive rate of <2% for all six β-lactams. Thus, the PBP transpeptidase signatures are robust indicators of MICs to different β-lactam antibiotics in clinical pneumococcal isolates and serve as an accurate alternative to phenotypic susceptibility testing.

Phage Conversion for β-Lactam Antibiotic Resistance of Staphylococcus aureus from Foods.

Science.gov (United States)

Lee, Young-Duck; Park, Jong-Hyun

2016-02-01

Temperate phages have been suggested to carry virulence factors and other lysogenic conversion genes that play important roles in pathogenicity. In this study, phage TEM123 in wild-type Staphylococcus aureus from food sources was analyzed with respect to its morphology, genome sequence, and antibiotic resistance conversion ability. Phage TEM123 from a mitomycin C-induced lysate of S. aureus was isolated from foods. Morphological analysis under a transmission electron microscope revealed that it belonged to the family Siphoviridae. The genome of phage TEM123 consisted of a double-stranded DNA of 43,786 bp with a G+C content of 34.06%. A bioinformatics analysis of the phage genome identified 43 putative open reading frames (ORFs). ORF1 encoded a protein that was nearly identical to the metallo-β-lactamase enzymes that degrade β-lactam antibiotics. After transduction to S. aureus with phage TEM123, the metallo-β-lactamase gene was confirmed in the transductant by PCR and sequencing analyses. In a β-lactam antibiotic susceptibility test, the transductant was more highly resistant to β-lactam antibiotics than S. aureus S133. Phage TEM123 might play a role in the transfer of β-lactam antibiotic resistance determinants in S. aureus. Therefore, we suggest that the prophage of S. aureus with its exotoxin is a risk factor for food safety in the food chain through lateral gene transfer.

Overcoming resistance to beta-lactamase inhibitors: comparing sulbactam to novel inhibitors against clavulanate resistant SHV enzymes with substitutions at Ambler position 244.

Science.gov (United States)

Thomson, Jodi M; Distler, Anne M; Bonomo, Robert A

2007-10-09

Amino acid changes at Ambler position R244 in class A TEM and SHV beta-lactamases confer resistance to ampicillin/clavulanate, a beta-lactam/beta-lactamase inhibitor combination used to treat serious infections. To gain a deeper understanding of this resistance phenotype, we investigated the activities of sulbactam and two novel penem beta-lactamase inhibitors with sp2 hybridized C3 carboxylates and bicyclic R1 side chains against a library of SHV beta-lactamase variants at the 244 position. Compared to SHV-1 expressed in Escherichia coli, all 19 R244 variants exhibited increased susceptibility to ampicillin/sulbactam, an important difference compared to ampicillin/clavulanate. Kinetic analyses of SHV-1 and three SHV R244 (-S, -Q, and -L) variants revealed the Ki for sulbactam was significantly elevated for the R244 variants, but the partition ratios, kcat/kinact, were markedly reduced (13 000 --> beta-lactamase was unmodified at 15 min. A parallel experiment with R244S demonstrated 70 and 88 +/- 3 Da fragments of sulbactam covalently attached to the beta-lactamase. We also observed that the Ki values of penems 1 and 2 were increased for R244 variants compared to those for SHV; however, these inhibitors effectively restored ampicillin susceptibility in vitro. Compared to that of sulbactam, the kcat/kinact values of penems for SHV-1 and R244S were low (affects beta-lactamase inactivators differently, but resistance can be overcome by designing penem inhibitors with strategic chemical properties that improve affinity and impair turnover.

Expression, purification, crystallization, and preliminary X-ray crystallographic analysis of OXA-17, an extended-spectrum {beta}-lactamase conferring severe antibiotic resistance

Energy Technology Data Exchange (ETDEWEB)

Lee, J. H., E-mail: msgjhlee@mju.ac.kr; Sohn, S. G., E-mail: sgsohn@mju.ac.kr; Jung, H. I., E-mail: jhinumber1@hanmail.net; An, Y. J., E-mail: anyj0120@hanmail.net; Lee, S. H., E-mail: sangheelee@mju.ac.kr [Myongji University, Drug Resistance Proteomics Laboratory, Department of Biological Sciences (Korea, Republic of)

2013-07-15

OXA-17, an extended-spectrum {beta}-lactamase (ESBL) conferring severe antibiotic resistance, hydrolytically inactivates {beta}-lactam antibiotics, inducing a lack of eradication of pathogenic bacteria by oxyimino {beta}-lactams and not helping hospital infection control. Thus, the enzyme is a potential target for developing antimicrobial agents against pathogens producing ESBLs. OXA-17 was purified and crystallized at 298 K. X-ray diffraction data from OXA-17 crystal have been collected to 1.85 A resolution using synchrotron radiation. The crystal of OXA-17 belongs to space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 48.37, b = 101.12, and c = 126.07 A. Analysis of the packing density shows that the asymmetric unit probably contains two molecules with a solvent content of 54.6%.

Immunological aspects of nonimmediate reactions to beta-lactam antibiotics.

Science.gov (United States)

Rodilla, Esther Morena; González, Ignacio Dávila; Yges, Elena Laffond; Bellido, Francisco Javier Múñoz; Bara, María Teresa Gracia; Toledano, Félix Lorente

2010-09-01

beta-lactam antibiotics are the agents most frequently implied in immune drug adverse reactions. These can be classified as immediate or nonimmediate according to the time interval between the last drug administration and their onset. Mechanisms of immediate IgE-mediated reactions are widely studied and are therefore better understood. Nonimmediate reactions include a broad number of clinical entities like mild maculopapular exanthemas, the most common, and other less frequent but more severe reactions such as Stevens-Johnson syndrome, toxic epidermal necrolysis, acute exanthematic pustulosis or cytopenias. These nonimmediate reactions are mainly mediated by T cells but the precise underlying mechanisms are not well elucidated. This fact complicates the allergological evaluation of patients with this type of reaction and available tests have demonstrated poor sensitivity and specificity.

Beta-lactam resistance among Enterobacteriaceae in Cambodia: The four-year itch

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Yannick Caron

2018-01-01

Full Text Available Although antibiotics are too often used inappropriately in Cambodia, published data on antimicrobial resistance in this country are scarce. Epidemic dissemination and the transfer of resistance genes to other bacterial species put the population at risk. The aim of this study was to evaluate the frequency and characteristics of extended-spectrum beta-lactamase (ESBL-producing Enterobacteriaceae (ESBL-E isolated in consecutive samples tested at Institut Pasteur du Cambodge over a 4-year period (2012–2015. Antimicrobial susceptibility testing was performed by disk diffusion on agar technique and the results were read automatically using an OSIRIS system. The Etest was used to determine minimum inhibitory concentrations (MIC for some resistance phenotypes. The strain most commonly identified was Escherichia coli (63.9%. The proportion of ESBL-E increased gradually over the study period, from 23.8% to 38.4%. ESBL was detected in 42.7% of the E. coli strains and 33.7% of all Klebsiella pneumoniae isolated. The proportion of ESBL-producing E. coli increased significantly from 28.9% in 2012 to 48.2% in 2015, while the increase for K. pneumoniae remained non-significant. Multidrug resistance was high in this Cambodian series, with some strains displaying resistance to all antibiotics available in the country. There is currently no established system for the surveillance of antimicrobial resistance in Cambodia. Collecting samples from clinical settings throughout the country is critical to assess the impact of antimicrobial drug use in patients in Cambodia and in the Mekong Region.

Beta-lactam resistance among Enterobacteriaceae in Cambodia: The four-year itch.

Science.gov (United States)

Caron, Yannick; Chheang, Rattanak; Puthea, Nop; Soda, Meng; Boyer, Sébastien; Tarantola, Arnaud; Kerléguer, Alexandra

2018-01-01

Although antibiotics are too often used inappropriately in Cambodia, published data on antimicrobial resistance in this country are scarce. Epidemic dissemination and the transfer of resistance genes to other bacterial species put the population at risk. The aim of this study was to evaluate the frequency and characteristics of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-E) isolated in consecutive samples tested at Institut Pasteur du Cambodge over a 4-year period (2012-2015). Antimicrobial susceptibility testing was performed by disk diffusion on agar technique and the results were read automatically using an OSIRIS system. The Etest was used to determine minimum inhibitory concentrations (MIC) for some resistance phenotypes. The strain most commonly identified was Escherichia coli (63.9%). The proportion of ESBL-E increased gradually over the study period, from 23.8% to 38.4%. ESBL was detected in 42.7% of the E. coli strains and 33.7% of all Klebsiella pneumoniae isolated. The proportion of ESBL-producing E. coli increased significantly from 28.9% in 2012 to 48.2% in 2015, while the increase for K. pneumoniae remained non-significant. Multidrug resistance was high in this Cambodian series, with some strains displaying resistance to all antibiotics available in the country. There is currently no established system for the surveillance of antimicrobial resistance in Cambodia. Collecting samples from clinical settings throughout the country is critical to assess the impact of antimicrobial drug use in patients in Cambodia and in the Mekong Region. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Coexistence of Extended Spectrum Beta-Lactamases, AmpC Beta-Lactamases and Metallo-Beta-Lactamases in Acinetobacter baumannii from burns patients: a report from a tertiary care centre of India

OpenAIRE

Gupta, V.; Garg, R.; Garg, S.; Chander, J.; Attri, A.K.

2013-01-01

Multidrug-resistant Acinetobacter baumanii is a major pathogen encountered in pyogenic infections, especially from burns patients in hospital settings. Often there is also coexistence of multiple beta-lactamase enzymes responsible for beta-lactam resistance in a single isolate, which further complicates treatment options. We conducted a study on burn wound pus samples obtained from the burns unit of our hospital. Phenotypic tests were used to determine the Extended Spectrum Beta-Lactamase, Am...

Phenotypic and Genotypic Detection of Metallo-beta-lactamases among Imipenem-Resistant Gram Negative Isolates

Directory of Open Access Journals (Sweden)

Mohammad Mohammadzadeh

2016-08-01

Full Text Available Background:   Imipenem-resistant gram negative bacteria, resulting from metallo-beta-lactamase (MBLs-producing strains have been reported to be among the important causes of nosocomial infections and of serious therapeutic problem worldwide. Because of their broad range, potent carbapenemase activity and resistance to inhibitors, these enzymes can confer resistance to almost all beta-lactams. The prevalence of metallo-beta-lactamase among imipenem-resistant Acinetobacter spp., Pseudomonas spp. and Enerobacteriaceae isolates is determined.Methods:   In this descriptive study 864 clinical isolates of Acinetobacter spp., Pseudomonas spp. and Enterobacteriaceae, were initially tested for imipenem susceptibility. The metallo-beta-lactamase production was detected using combined disk diffusion, double disk synergy test, and Hodge test. Then all imipenem resistant isolates were tested by PCR for imp, vim and ndm genes. Results:   Among 864 isolates, 62 (7.17 % were imipenem-resistant. Positive phonetypic test for metallo-beta-lactamase was 40 (64.5%, of which 24 (17.1% and 16 (9.2% isolates were Acinetobacter spp. and Pseudomonas spp., respectively. By PCR method 30 (48.4% of imipenem resistant Acinetobacter, and Pseudomonas isolates were positive for MBL-producing genes. None of the Enterobacteriaceae isolates were positive for metallo-beta-lactamase activity. Conclusion:   The results of this study are indicative of the growing number of nosocomial infections associated with multidrug-resistant gram negative bacteria in this region leading to difficulties in antibiotic therapy. Thereby, using of phenotypic methods can be helpful for management of this problem.

Extended spectrum beta-lactamase-producing Escherichia coli forms filaments as an initial response to cefotaxime treatment

DEFF Research Database (Denmark)

Kjeldsen, Thea S. B.; Sommer, Morten Otto Alexander; Olsen, John E.

2015-01-01

Background: beta-lactams target the peptidoglycan layer in the bacterial cell wall and most beta-lactam antibiotics cause filamentation in susceptible Gram-negative bacteria at low concentrations. The objective was to determine the initial morphological response of cephalosporin resistant CTX-M-1......-producing E. coli to cefotaxime and to determine whether the response depended on the growth phase of the bacterium and the concentration of antibiotic. Results: Two antibiotic resistant strains carrying bla(CTX-M-1) on the chromosome and on an IncI1 plasmid and three sensitive strains were used...... to cefotaxime. The filament formation was restricted to early growth phases and the time the cells grew as filaments was antibiotic concentration dependent. This indicates that antibiotic resistant E. coli undergo the same morphological changes as sensitive bacteria in the presence of beta-lactam antibiotic...

Quantification and characterization of β-lactam resistance genes in 15 sewage treatment plants from East Asia and North America.

Science.gov (United States)

Yang, Ying; Zhang, Tong; Zhang, Xu-Xiang; Liang, Da-Wei; Zhang, Ming; Gao, Da-Wen; Zhu, He-Guang; Huang, Qing-Guo; Fang, Herbert H P

2012-09-01

The emerging antibiotic resistance genes in the aquatic environment have aroused public concern. As β-lactam is the most widely used group of antibiotics, β-lactam resistance genes were selected to investigate their distribution and diversity in the activated sludge from 15 geographically different sewage treatment plants (STPs) of China, Singapore, USA, and Canada. Specific PCR and quantitative real-time PCR (q-PCR) were used to investigate the occurrence and abundance of nine β-lactam resistance genes. Five genes (OXA-1, OXA-2, OXA-10, ampC, and TEM-1) were detected in most of the sludge collected, while three genes (mecA, CTX-M-1, and SME) were not found in any sludge sample. The total abundances of the six detected β-lactam resistance genes in the 15 STPs varied from 5.34 × 10(1) copies/ng DNA (ampC) to 5.49 × 10(4) copies/ng DNA (OXA-1). Overall, OXA-1 had the highest total concentration, followed by IMP and OXA-10. Noticeably, the abundances of TEM-1 in Chinese STPs were generally higher than those in the STPs of other countries, while the abundances of OXA-2 and IMP in the STPs of North America were much greater than those of East Asia. A total of 78 clones carrying β-lactam resistance genes were randomly selected from six clone libraries for phylogenetic diversity analysis; the similarity of these cloned genes to known β-lactam resistance genes with sequence identities ranged from 96% to 100%. Furthermore, OXA-1, ampC, and IMP were found to be more diverse than the other β-lactam resistance genes.

An international multicenter study of antimicrobial consumption and resistance in Staphylococcus aureus isolates from 15 hospitals in 14 countries

DEFF Research Database (Denmark)

Westh, Henrik Torkil; Zinn, Christina Scheel; Rosdahl, Vibeke Thamdrup

2004-01-01

of therapeutical subgroups of antimicrobials varied significantly between hospitals. A positive correlation was found between S. aureus resistance to methicillin (MRSA) and consumption of beta-lactam combinations, between resistance to quinolones and consumption of beta-lactam combinations and carbapenems....... Consumption of beta-lactamase-sensitive antibiotics (penicillin) was positively correlated to consumption of beta-lactamase-resistant penicillins and negatively correlated to consumption of carbapenems, quinolones, and glycopeptides, whereas consumption of cephalosporins was positively correlated...

Exposure to β-lactams results in the alteration of penicillin-binding proteins in Clostridium perfringens.

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Park, Miseon; Rafii, Fatemeh

2017-06-01

Clostridium perfringens causes a variety of mild to severe infections in humans and other animals. A decrease in the affinity of penicillin-binding protein (PBP) transpeptidases for β-lactams is considered one of the mechanisms of β-lactam resistance in bacteria. Two strains of C. perfringens isolated from bovines and one isolated from a chicken, which had decreased susceptibility to β-lactams, had variations in the amino acid sequences of the central penicillin-binding regions of the PBPs. β-Lactam-resistant mutants of another C. perfringens strain, ATCC 13124, were selected in vitro to determine the effects of exposure to β-lactams on the PBP genes. Cultures of the wild type rapidly developed resistance to penicillin G, cephalothin and ceftriaxone. The susceptibilities of all of the selected mutants to some other β-lactams also decreased. The largest PBP found in C. perfringens, CPF_2395, appeared to be the primary target of all three drugs. Strain resistant to penicillin G had mutation resulting in the substitution of one amino acid within the central penicillin-binding/transpeptidase domain, but the ceftrioxane and cephalothin-resistant strains had mutations resulting in the substitution of two amino acids in this region. The cephalothin-resistant mutant also had additional mutations in the CPF_0340 and CPF_2218 genes in this critical region. No other mutations were observed in the three other PBPs of the in vitro resistant mutants. Resistance development also altered the growth rate and cell morphology of the mutants, so in addition to the PBPs, some other genes, including regulatory genes, may have been affected during the interaction with β-lactam antibiotics. This is the first study showing the effects of β-lactam drugs on the substitution of amino acids in PBPs of C. perfringens and points to the need for studies to detect other unknown alterations affecting the physiology of resistant strains. Published by Elsevier Ltd.

Inoculum effect of high concentrations of methicillin-susceptible Staphylococcus aureus on the efficacy of cefazolin and other beta-lactams.

Science.gov (United States)

Saeki, Masachika; Shinagawa, Masaaki; Yakuwa, Yuki; Nirasawa, Shinya; Sato, Yuki; Yanagihara, Nozomi; Takahashi, Satoshi

2018-03-01

The existence of a cefazolin inoculum effect (InE) of methicillin-susceptible Staphylococcus aureus (MSSA), which is speculated to be a reason for cefazolin treatment failure in MSSA infections, is controversial. In Japan, although cefazolin is one of the therapeutic choices for patients with MSSA infection, there are few reports of this effect. Additionally, the association between InE and blaZ type in beta-lactams other than cefazolin has not been well documented. In this study, we confirmed an MSSA InE in several beta-lactams, including cefazolin, and its relationship with blaZ, using 52 MSSA isolates from blood cultures. Three isolates (5.8%) that possessed type A blaZ showed a pronounced cefazolin InE. Five isolates (9.6%) showed pronounced InE with sulbactam/ampicillin; four isolates had type C blaZ and one had type A blaZ. However, we confirmed InE in MSSA isolates with blaZ not only type A and C but also B and D. For cefotaxime, ceftriaxone, imipenem, and meropenem, regardless of the presence of blaZ, we did not observe a significant increase in MICs at a high inoculum of MSSA. Hence, our results suggest that the above four beta-lactams are good alternatives to cefazolin if InE leads to treatment failure in a patient. Copyright © 2017 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Self-resistance in Streptomyces, with Special Reference to β-Lactam Antibiotics.

Science.gov (United States)

Ogawara, Hiroshi

2016-05-10

Antibiotic resistance is one of the most serious public health problems. Among bacterial resistance, β-lactam antibiotic resistance is the most prevailing and threatening area. Antibiotic resistance is thought to originate in antibiotic-producing bacteria such as Streptomyces. In this review, β-lactamases and penicillin-binding proteins (PBPs) in Streptomyces are explored mainly by phylogenetic analyses from the viewpoint of self-resistance. Although PBPs are more important than β-lactamases in self-resistance, phylogenetically diverse β-lactamases exist in Streptomyces. While class A β-lactamases are mostly detected in their enzyme activity, over two to five times more classes B and C β-lactamase genes are identified at the whole genomic level. These genes can subsequently be transferred to pathogenic bacteria. As for PBPs, two pairs of low affinity PBPs protect Streptomyces from the attack of self-producing and other environmental β-lactam antibiotics. PBPs with PASTA domains are detectable only in class A PBPs in Actinobacteria with the exception of Streptomyces. None of the Streptomyces has PBPs with PASTA domains. However, one of class B PBPs without PASTA domain and a serine/threonine protein kinase with four PASTA domains are located in adjacent positions in most Streptomyces. These class B type PBPs are involved in the spore wall synthesizing complex and probably in self-resistance. Lastly, this paper emphasizes that the resistance mechanisms in Streptomyces are very hard to deal with, despite great efforts in finding new antibiotics.

Synthesis of 5/7-, 5/8- and 5/9-bicyclic lactam templates as constraints for external beta-turns.

Science.gov (United States)

Duggan, Heather M E; Hitchcock, Peter B; Young, Douglas W

2005-06-21

The 5/7-, 5/8- and 5/9-bicyclic lactams 3, 17, 5 and 6 have been synthesised as single diastereoisomers by a route involving ring closing olefin metathesis. The X-ray crystal structure of the amino acid hydrochloride has been carried out and compared to that of the saturated external beta-turn constraint 18.

Subinhibitory Concentrations of Bacteriostatic Antibiotics Induce relA-Dependent and relA-Independent Tolerance to beta-Lactams

Czech Academy of Sciences Publication Activity Database

Kudrin, P.; Varik, V.; Oliveira, S. R. A.; Beljantseva, J.; Del Peso Santos, T.; Dzhygyr, I.; Rejman, Dominik; Cava, F.; Tenson, T.; Hauryliuk, V.

2017-01-01

Roč. 61, č. 4 (2017), č. článku e02173-16. ISSN 0066-4804 R&D Projects: GA ČR GA15-11711S Institutional support: RVO:61388963 Keywords : beta-lactam * RelA * antibiotics * mupirocin * persistence * ppGpp Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 4.302, year: 2016 http://aac.asm.org/content/61/4/e02173-16.full

Characterization of Multidrug Resistant Extended-Spectrum Beta-Lactamase-Producing Escherichia coli among Uropathogens of Pediatrics in North of Iran

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Mohammad Sadegh Rezai

2015-01-01

Full Text Available Escherichia coli remains as one of the most important bacteria causing infections in pediatrics and producing extended-spectrum beta-lactamases (ESBLs making them resistant to beta-lactam antibiotics. In this study we aimed to genotype ESBL-producing E. coli isolates from pediatric patients for ESBL genes and determine their association with antimicrobial resistance. One hundred of the E. coli isolates were initially considered ESBL producing based on their MIC results. These isolates were then tested by polymerase chain reaction (PCR for the presence or absence of CTX, TEM, SHV, GES, and VEB beta-lactamase genes. About 30.5% of isolated E. coli was ESBL-producing strain. The TEM gene was the most prevalent (49% followed by SHV (44%, CTX (28%, VEB (8%, and GES (0% genes. The ESBL-producing E. coli isolates were susceptible to carbapenems (66% and amikacin (58% and showed high resistance to cefixime (99%, colistin (82%, and ciprofloxacin (76%. In conclusion, carbapenems were the most effective antibiotics against ESBl-producing E. coli in urinary tract infection in North of Iran. The most prevalent gene is the TEM-type, but the other resistant genes and their antimicrobial resistance are on the rise.

Evidence for the evolutionary steps leading to mecA-mediated β-lactam resistance in staphylococci

DEFF Research Database (Denmark)

Rolo, Joana; Worning, Peder; Boye Nielsen, Jesper

2017-01-01

the most primitive staphylococci. In this study we aimed to identify evolutionary steps linking these mecA precursors to the β-lactam resistance gene mecA and the resistance phenotype. We sequenced genomes of 106 S. sciuri, S. vitulinus and S. fleurettii strains and determined their oxacillin...

Lactam hydrolysis catalyzed by mononuclear metallo-ß-bactamases

DEFF Research Database (Denmark)

Olsen, Lars; Antony, J; Ryde, U

2003-01-01

Two central steps in the hydrolysis of lactam antibiotics catalyzed by mononuclear metallo-beta-lactamases, formation of the tetrahedral intermediate and its breakdown by proton transfer, are studied for model systems using the density functional B3LYP method. Metallo-beta-lactamases have two metal...

The effect of a beta-lactamase inhibitor peptide on bacterial membrane structure and integrity: a comparative study.

Science.gov (United States)

Alaybeyoglu, Begum; Uluocak, Bilge Gedik; Akbulut, Berna Sariyar; Ozkirimli, Elif

2017-05-01

Co-administration of beta-lactam antibiotics and beta-lactamase inhibitors has been a favored treatment strategy against beta-lactamase-mediated bacterial antibiotic resistance, but the emergence of beta-lactamases resistant to current inhibitors necessitates the discovery of novel non-beta-lactam inhibitors. Peptides derived from the Ala46-Tyr51 region of the beta-lactamase inhibitor protein are considered as potent inhibitors of beta-lactamase; unfortunately, peptide delivery into the cell limits their potential. The properties of cell-penetrating peptides could guide the design of beta-lactamase inhibitory peptides. Here, our goal is to modify the peptide with the sequence RRGHYY that possesses beta-lactamase inhibitory activity under in vitro conditions. Inspired by the work on the cell-penetrating peptide pVEC, our approach involved the addition of the N-terminal hydrophobic residues, LLIIL, from pVEC to the inhibitor peptide to build a chimera. These residues have been reported to be critical in the uptake of pVEC. We tested the potential of RRGHYY and its chimeric derivative as a beta-lactamase inhibitory peptide on Escherichia coli cells and compared the results with the action of the antimicrobial peptide melittin, the beta-lactam antibiotic ampicillin, and the beta-lactamase inhibitor potassium clavulanate to get mechanistic details on their action. Our results show that the addition of LLIIL to the N-terminus of the beta-lactamase inhibitory peptide RRGHYY increases its membrane permeabilizing potential. Interestingly, the addition of this short stretch of hydrophobic residues also modified the inhibitory peptide such that it acquired antimicrobial property. We propose that addition of the hydrophobic LLIIL residues to the peptide N-terminus offers a promising strategy to design novel antimicrobial peptides in the battle against antibiotic resistance. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd. Copyright © 2017 European

Penicillin G acylase from Achromobacter sp CCM 4824 An efficient biocatalyst for syntheses of beta-lactam antibiotics under conditions employed in large-scale processes

Czech Academy of Sciences Publication Activity Database

Bečka, Stanislav; Štěpánek, Václav; Vyasarayani, W. R.; Grulich, Michal; Maršálek, Jaroslav; Plháčková, Kamila; Dobišová, Marie; Marešová, Helena; Plačková, Martina; Valešová, Renata; Palyzová, Andrea; Datla, A.; Ashar, T. K.; Kyslík, Pavel

2014-01-01

Roč. 98, č. 3 (2014), s. 1195-1203 ISSN 0175-7598 Institutional support: RVO:61388971 Keywords : Achromobacter sp. * Penicillin G acylase * beta-Lactam antibiotics Subject RIV: EE - Microbiology, Virology Impact factor: 3.337, year: 2014

Neutron Diffraction Studies of a Class A beta-Lactamase Toho-1 E166A/R274N/R276N Triple Mutant

International Nuclear Information System (INIS)

Blakeley, Matthew P.; Chen, Yu; Afonine, Pavel

2010-01-01

beta-Lactam antibiotics have been used effectively over several decades against many types of bacterial infectious diseases. However, the most common cause of resistance to the beta-lactam antibiotics is the production of beta-lactamase enzymes that inactivate beta-lactams by rapidly hydrolyzing the amide group of the beta-lactam ring. Specifically, the class A extended-spectrum beta-lactamases (ESBLs) and inhibitor-resistant enzymes arose that were capable of hydrolyzing penicillins and the expanded-spectrum cephalosporins and monobactams in resistant bacteria, which lead to treatment problems in many clinical settings. A more complete understanding of the mechanism of catalysis of these ESBL enzymes will impact current antibiotic drug discovery efforts. Here, we describe the neutron structure of the class A, CTX-M-type ESBL Toho-1 E166A/R274N/R276N triple mutant in its apo form, which is the first reported neutron structure of a beta-lactamase enzyme. This neutron structure clearly reveals the active-site protonation states and hydrogen-bonding network of the apo Toho-1 ESBL prior to substrate binding and subsequent acylation. The protonation states of the active-site residues Ser70, Lys73, Ser130, and Lys234 in this neutron structure are consistent with the prediction of a proton transfer pathway from Lys73 to Ser130 that is likely dependent on the conformation of Lys73, which has been hypothesized to be coupled to the protonation state of Glu166 during the acylation reaction. Thus, this neutron structure is in agreement with a proposed mechanism for acylation that identifies Glu166 as the general base for catalysis.

Validation of the charm 3 SL3 beta-lactam test for screening raw milk in compliance with the U.S. pasteurized milk ordinance. Performance Tested Method 071002.

Science.gov (United States)

Salter, Robert S; Douglas, David; McRobbie, Lindsey; Quintana, Julio; Legg, David; Schwartz, Janine; Conaway, David; McPhee, Carla; Saul, Steven; Markovsky, Robert

2011-01-01

The Charm 3 SL3 beta-Lactam Test is a 3 min receptor-based lateral-flow Rapid One-Step Assay (ROSA) that detects the six beta-lactam drugs of concern approved for dairy cattle in the United States. The method is a biochemical formulation change of the SL3 beta-Lactam Test evaluated and approved in 2007. The Charm 3 SL3 was evaluated under the AOAC Research Institute Performance Tested Method (PTM) program following the protocol of the U.S. Food and Drug Administration, Center for Veterinary Medicine. The method was approved as PTM 071002 on May 8, 2009. The following drugs were detected in three combined lots: penicillin G at 3.8 ppb, ampicillin at 8.0 ppb, amoxicillin at 8.4 ppb, cephapirin at 20.0 ppb, ceftiofur (total metabolites) at 79 ppb, and cloxacillin at 8.6 ppb > or = 90% of the time with 95% confidence. These detection levels are lower than, but within 75% of, the U.S. Safe Level/Tolerances. Lot-to-lot repeatability was typically within 20% of these determined levels. The test kit was found to be suitable for testing thawed frozen samples. It was also found to respond with equal or better sensitivity to samples that contained incurred analytes, i.e., both the microbiologically active parent drug and its active metabolites. There were no interferences from somatic cells at 1.1 million/mL, bacterial cells at 300 000 CFU/mL, or 32 other non-beta-lactam drugs at 100 ppb. Ruggedness experiments indicated that the test procedure is robust. These results meet the fit-for-purpose approval criteria for inclusion in the National Conference for Interstate Milk Shipments milk testing program.

Production of low-affinity penicillin-binding protein by low- and high-resistance groups of methicillin-resistant Staphylococcus aureus.

Science.gov (United States)

Murakami, K; Nomura, K; Doi, M; Yoshida, T

1987-01-01

Methicillin- and cephem-resistant Staphylococcus aureus (137 strains) for which the cefazolin MICs are at least 25 micrograms/ml could be classified into low-resistance (83% of strains) and high-resistance (the remaining 17%) groups by the MIC of flomoxef (6315-S), a 1-oxacephalosporin. The MICs were less than 6.3 micrograms/ml and more than 12.5 micrograms/ml in the low- and high-resistance groups, respectively. All strains produced penicillin-binding protein 2' (PBP 2'), which has been associated with methicillin resistance and which has very low affinity for beta-lactam antibiotics. Production of PBP 2' was regulated differently in low- and high-resistance strains. With penicillinase-producing strains of the low-resistance group, cefazolin, cefamandole, and cefmetazole induced PBP 2' production about 5-fold, while flomoxef induced production 2.4-fold or less. In contrast, penicillinase-negative variants of low-resistance strains produced PBP 2' constitutively in large amounts and induction did not occur. With high-resistance strains, flomoxef induced PBP 2' to an extent similar to that of cefazolin in both penicillinase-producing and -negative strains, except for one strain in which the induction did not occur. The amount of PBP 2' induced by beta-lactam antibiotics in penicillinase-producing strains of the low-resistance group correlated well with resistance to each antibiotic. Large amounts of PBP 2' in penicillinase-negative variants of the low-resistance group did not raise the MICs of beta-lactam compounds, although these strains were more resistant when challenged with flomoxef for 2 h. Different regulation of PBP 2' production was demonstrated in the high- and low-resistance groups, and factor(s) other than PBP 2' were suggested to be involved in the methicillin resistance of high-resistance strains. Images PMID:3499861

CLONING, SEQUENCE ANALYSIS, AND CHARACTERIZATION OF PUTATIVE BETA-LACTAMASE OF STENOTROPHOMONAS MALTOPHILIA

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Chong Seng Shueh

2012-10-01

Full Text Available The main objective of current study was to explore the function of chromosomal putative beta-lactamase gene (smlt 0115 in clinical Stenotrophomonas maltophilia. Antibiotic susceptibility test (AST screening for current antimicrobial drugs was done and Minimum Inhibitory Concentration (MIC level towards beta-lactams was determined by E-test. Putative beta-lactamase gene of S. maltophilia was amplified via PCR, with specific primers, then cloned into pET-15 expression plasmid and transformed into Escherichia coli BL21. The gene was sequenced and analyzed. The expressed protein was purified by affinity chromatography and the kinetic assay was performed. S. maltophilia ATCC 13637 was included in this experiment. Besides, a hospital strain which exhibited resistant to a series of beta-lactams including cefepime was identified via AST and MIC, hence it was named as S2 strain and was considered in this study. Sequencing result showed that putative beta-lactamase gene obtained from ATCC 13637 and S2 strains were predicted to have cephalosporinase activity by National Center for Biotechnology Information (NCBI blast program. Differences in the sequences of both ATCC 13637 and S2 strains were found via ClustalW alignment software. Kinetic assay proved a cephalosporinase characteristic produced by E. coli BL21 clone that overexpressed the putative beta-lactamase gene cloned under the control of an external promoter. Yet, expressed protein purified from S2 strain had high catalytic activity against beta-lactam antibiotics which was 14-fold higher than expressed protein purified from ATCC 13637 strain. This study represents the characterization analysis of putative beta-lactamase gene (smlt 0115 of S. maltophilia. The presence of the respective gene in the chromosome of S. maltophilia suggested that putative beta-lactamase gene (smlt 0115 of S. maltophilia plays a role in beta-lactamase resistance.

Metalo-beta-lactamases Metallo-beta-lactamases

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Rodrigo Elisandro Mendes

2006-04-01

Full Text Available Nos últimos anos tem sido observada maior incidência de bacilos Gram-negativos resistentes a cefalosporinas de espectro ampliado no ambiente hospitalar, ocasionando, assim, maior uso de betalactâmicos mais potentes, como os carbapenens. A utilização de carbapenens exerce maior pressão seletiva sobre a microbiota hospitalar, o que pode ocasionar aumento da resistência a esses agentes. Entre os mecanismos de resistência a carbapenens mais comumente identificados estão a produção de betalactamases, como, por exemplo, as pertencentes à classe D de Ambler e as que pertencem à classe B de Ambler, ou metalo-beta-lactamases (MbetaL. Essas últimas hidrolisam todos betalactâmicos comercialmente disponíveis, sendo a única exceção o monobactam aztreonam. Desde o início da década de 1990, novos genes que codificam MbetaLs têm sido descritos em microrganismos clinicamente importantes, como Pseudomonas spp., Acinetobacter spp. e membros da família Enterobacteriaceae. O encontro desses microrganismos não-sensíveis a carbapenens pode ser submetido a metodologias fenotípicas para detecção da produção de MbetaL com o intuito de auxiliar a Comissão de Controle de Infecção Hospitalar (CCIH e prevenir a disseminação desses determinantes de resistência, uma vez que genes que codificam MbetaLs estão contidos em estruturas genéticas que propiciam sua mobilidade de forma muito efetiva, sendo então facilmente disseminados.Increase isolation of Gram-negative bacilli resistant to broad-spectrum cephalosporin has been observed during the last few years, thus determining the use of more potent beta-lactams, such as carbapenems. The use of these antimicrobial agents may lead to the emergence of carbapenem resistant Gram-negative bacilli in the nosocomial environment. Carbapenem resistance may be due to the production of Ambler class D beta-lactamase or Ambler class B beta-lactamase, also called metallo-beta-lactamase (MbetaL. Apart from

The road to avibactam: the first clinically useful non-β-lactam working somewhat like a β-lactam.

Science.gov (United States)

Wang, David Yuxin; Abboud, Martine I; Markoulides, Marios S; Brem, Jürgen; Schofield, Christopher J

2016-06-01

Avibactam, which is the first non-β-lactam β-lactamase inhibitor to be introduced for clinical use, is a broad-spectrum serine β-lactamase inhibitor with activity against class A, class C, and, some, class D β-lactamases. We provide an overview of efforts, which extend to the period soon after the discovery of the penicillins, to develop clinically useful non-β-lactam compounds as antibacterials, and, subsequently, penicillin-binding protein and β-lactamase inhibitors. Like the β-lactam inhibitors, avibactam works via a mechanism involving covalent modification of a catalytically important nucleophilic serine residue. However, unlike the β-lactam inhibitors, avibactam reacts reversibly with its β-lactamase targets. We discuss chemical factors that may account for the apparently special nature of β-lactams and related compounds as antibacterials and β-lactamase inhibitors, including with respect to resistance. Avenues for future research including non-β-lactam antibacterials acting similarly to β-lactams are discussed.

Genotypic and phenotypic β-lactam resistance and presence of PVL gene in Staphylococci from dry bovine udder.

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Vinodkumar Kulangara

Full Text Available Dairy cows affected with subclinical mastitis can be sources of virulent, antimicrobial-resistant Staphylococci to humans because of the excretion of the bacteria through their milk. This study focussed on the phenotypic and genotypic antibiotic resistance patterns of Staphylococci isolated from dairy cows in early dry period. Among 96 isolates of Gram positive cocci from 157 cows, 76 were identified as Coagulase Negative Staphylococci and the remaining 20 were Staphylococcus aureus. Typical amplicons of coagulase gene were obtained for all 20 samples of S. aureus with three major coagulase types being identified as giving 627 bp (40%, 910 bp (35% and 710 bp (25% long PCR products. The groEL gene was amplified in PCR of all 76 isolates of Coagulase Negative Staphylococci, and incubation of PCR products with restriction enzyme PvuII yielded three distinct PCR-RFLP fragment patterns bearing resemblance to S. chromogenes and S. hyicus. Highest sensitivity of Coagulase Negative Staphylococci was noted for Azithromycin (92.5% and the least to Tetracyclines (76.3%, whereas for S. aureus, it was Cefoperazone (95% and Azithromycin (72.2% respectively. Phenotypic resistance to Oxacillin (25 isolates, and Cefoxitin (11 isolates was detected by dilution method with a commercial strip (Ezy MICTM. Genotypic resistance to β-Lactam antibiotics was found in 65 (34 with mecA gene and 31 with blaZ gene isolates. Eighteen isolates possessed both the genes, with the PVL gene for virulence being detected in five of them. Nine isolates which had mecA gene were phenotypically susceptible to oxacillin while phenotypic resistance to oxacillin was observed in seven isolates that did not have either mecA or blaZ gene. This is the first report of persistent Staphylococcal infections possessing PVL gene and high level of genotypic resistance to β-Lactam antibiotics in small- holder dairy cattle from India.

Genotypic and phenotypic β-lactam resistance and presence of PVL gene in Staphylococci from dry bovine udder

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Sivasailam, Asok; Sasidharan, Suchithra; Kollannur, Justin Davis; Syam, Radhika

2017-01-01

Dairy cows affected with subclinical mastitis can be sources of virulent, antimicrobial-resistant Staphylococci to humans because of the excretion of the bacteria through their milk. This study focussed on the phenotypic and genotypic antibiotic resistance patterns of Staphylococci isolated from dairy cows in early dry period. Among 96 isolates of Gram positive cocci from 157 cows, 76 were identified as Coagulase Negative Staphylococci and the remaining 20 were Staphylococcus aureus. Typical amplicons of coagulase gene were obtained for all 20 samples of S. aureus with three major coagulase types being identified as giving 627 bp (40%), 910 bp (35%) and 710 bp (25%) long PCR products. The groEL gene was amplified in PCR of all 76 isolates of Coagulase Negative Staphylococci, and incubation of PCR products with restriction enzyme PvuII yielded three distinct PCR-RFLP fragment patterns bearing resemblance to S. chromogenes and S. hyicus. Highest sensitivity of Coagulase Negative Staphylococci was noted for Azithromycin (92.5%) and the least to Tetracyclines (76.3%), whereas for S. aureus, it was Cefoperazone (95%) and Azithromycin (72.2%) respectively. Phenotypic resistance to Oxacillin (25 isolates), and Cefoxitin (11 isolates) was detected by dilution method with a commercial strip (Ezy MICTM). Genotypic resistance to β-Lactam antibiotics was found in 65 (34 with mecA gene and 31 with blaZ gene) isolates. Eighteen isolates possessed both the genes, with the PVL gene for virulence being detected in five of them. Nine isolates which had mecA gene were phenotypically susceptible to oxacillin while phenotypic resistance to oxacillin was observed in seven isolates that did not have either mecA or blaZ gene. This is the first report of persistent Staphylococcal infections possessing PVL gene and high level of genotypic resistance to β-Lactam antibiotics in small- holder dairy cattle from India. PMID:29091956

In vitro interactions between different beta-lactam antibiotics and fosfomycin against bloodstream isolates of enterococci.

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Pestel, M; Martin, E; Aucouturier, C; Lemeland, J F; Caron, F

1995-01-01

The effects of 16 different beta-lactam-fosfomycin combinations against 50 bloodstream enterococci were compared by a disk diffusion technique. Cefotaxime exhibited the best interaction. By checkerboard studies, the cefotaxime-fosfomycin combination provided a synergistic bacteriostatic effect against 45 of the 50 isolates (MIC of cefotaxime at which 90% of the isolates were inhibited, >2,048 micrograms/ml; MIC of fosfomycin at which 90% of the isolates were inhibited, 128 micrograms/ml; mean of fractional inhibitory concentration indexes, 0.195). By killing curves, cefotaxime (at 64 micrograms/ml) combined with fosfomycin (at > or = 64 micrograms/ml) was bactericidal against 6 of 10 strains tested. PMID:8619593

The role of outer membrane in Serratia marcescens intrinsic resistance to antibiotics.

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Sánchez, L; Ruiz, N; Leranoz, S; Viñas, M; Puig, M

1997-09-01

Three different porins from Serratia marcescens were described. They were named Omp1, Omp2 and Omp3 and their molecular weights were 42, 40 and 39 kDa respectively. Omp2 and Omp3 showed osmoregulation and thermoregulation in a similar way to OmpC and OmpF of Escherichia coli. Permeability coefficients of the outer membrane of this species were calculated following the Zimmermann and Rosselet method. P values were similar to those obtained in Escherichia coli, which suggests that the chromosomal beta-lactamase would play a major role in the resistance of Serratia marcescens to beta-lactam antibiotics. Both MIC values and permeabilities were modified by salycilates and acetylsalycilate. Synergism between the outer membrane and the beta-lactamase was also evaluated. When bacteria grew in the presence of a beta-lactam in the medium, the beta-lactamase accounted for most of the resistance.

Correlation between antimicrobial consumption and antimicrobial resistance of Pseudomonas aeruginosa in a hospital setting: a 10-year study.

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Mladenovic-Antic, S; Kocic, B; Velickovic-Radovanovic, R; Dinic, M; Petrovic, J; Randjelovic, G; Mitic, R

2016-10-01

Antimicrobial resistance is one of the greatest threats to human health. One of the most important factors leading to the emergence of resistant bacteria is overuse of antibiotics. The purpose of this study was to investigate the correlation between antimicrobial usage and bacterial resistance of Pseudomonas aeruginosa (P. aeruginosa) over a 10-year period in the Clinical Center Niš, one of the biggest tertiary care hospitals in Serbia. We focused on possible relationships between the consumption of carbapenems and beta-lactam antibiotics and the rates of resistance of P. aeruginosa to carbapenems. We recorded utilization of antibiotics expressed as defined daily doses per 100 bed days (DBD). Bacterial resistance was reported as the percentage of resistant isolates (percentage of all resistant and intermediate resistant strains) among all tested isolates. A significant increasing trend in resistance was seen in imipenem (P resistance to amikacin (P resistance to imipenem in P. aeruginosa shows significance (P resistance to meropenem showed a trend towards significance (P > 0·05, Pearson r = 0·607). We found a very good correlation between the use of all beta-lactam and P. aeruginosa resistance to carbapenems (P antimicrobial resistance to carbapenems, significant correlations between the consumption of antibiotics, especially carbapenems and beta-lactams, and rates of antimicrobial resistance of P. aeruginosa to imipenem and meropenem. © 2016 John Wiley & Sons Ltd.

Differential fate of erythromycin and beta-lactam resistance genes from swine lagoon waste under different aquatic conditions

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Knapp, Charles W., E-mail: charles.knapp@strath.ac.u [David Livingstone Centre for Sustainability, Department of Civil Engineering, University of Strathclyde, 50 Richmond Street, Glasgow, G1 1XN (United Kingdom); School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, NE1 7RU (United Kingdom); Zhang, Wen; Sturm, Belinda S.M. [Department of Civil, Environmental and Architectural Engineering, University of Kansas, Lawrence, KS 66045 (United States); Graham, David W. [School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, NE1 7RU (United Kingdom); Department of Civil, Environmental and Architectural Engineering, University of Kansas, Lawrence, KS 66045 (United States)

2010-05-15

The attenuation and fate of erythromycin-resistance-methylase (erm) and extended-spectrum beta-lactamse (bla) genes were quantified over time in aquatic systems by adding 20-L swine waste to 11,300-L outdoor mesocosms that simulated receiving water conditions below intensive agricultural operations. The units were prepared with two different light-exposure scenarios and included artificial substrates to assess gene movement into biofilms. Of eleven genes tested, only erm(B), erm(F), bla{sub SHV} and bla{sub TEM} were found in sufficient quantity for monitoring. The genes disappeared rapidly from the water column and first-order water-column disappearance coefficients were calculated. However, detected gene levels became elevated in the biofilms within 2 days, but then disappeared over time. Differences were observed between sunlight and dark treatments and among individual genes, suggesting that ecological and gene-specific factors play roles in the fate of these genes after release into the environment. Ultimately, this information will aid in generating better predictive models for gene fate. - The disappearance and fate of erythromycin-resistance-methylase and beta-lactamase genes were monitored in outdoor mesocosms under different light conditions.

A fitness cost associated with the antibiotic resistance enzyme SME-1 beta-lactamase.

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Marciano, David C; Karkouti, Omid Y; Palzkill, Timothy

2007-08-01

The bla(TEM-1) beta-lactamase gene has become widespread due to the selective pressure of beta-lactam use and its stable maintenance on transferable DNA elements. In contrast, bla(SME-1) is rarely isolated and is confined to the chromosome of carbapenem-resistant Serratia marcescens strains. Dissemination of bla(SME-1) via transfer to a mobile DNA element could hinder the use of carbapenems. In this study, bla(SME-1) was determined to impart a fitness cost upon Escherichia coli in multiple genetic contexts and assays. Genetic screens and designed SME-1 mutants were utilized to identify the source of this fitness cost. These experiments established that the SME-1 protein was required for the fitness cost but also that the enzyme activity of SME-1 was not associated with the fitness cost. The genetic screens suggested that the SME-1 signal sequence was involved in the fitness cost. Consistent with these findings, exchange of the SME-1 signal sequence for the TEM-1 signal sequence alleviated the fitness cost while replacing the TEM-1 signal sequence with the SME-1 signal sequence imparted a fitness cost to TEM-1 beta-lactamase. Taken together, these results suggest that fitness costs associated with some beta-lactamases may limit their dissemination.

Molecular Level Investigation of Staphylococci’s Resistance Mechanisms to Antibiotics

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Lavinia Lorena PRUTEANU

2017-09-01

Full Text Available Polymerase chain reaction (PCR techniques development allows elaboration of many assays for identification of bacteria’s resistance mechanisms to antibiotics. Following this idea, the results of molecular level investigation of bacteria’s resistance mechanisms to antibiotics may give many opportunities to find more rapid methods for identifying the genes which are responsible for antibiotic resistance induction. The aim of this study was to investigate antibiotic resistance genes in Staphylococcus bacteria on molecular level. As classes of antibiotics it was used macrolides-lincosamides-streptogramin B (MLSB and beta-lactams. In the proposed study the bacterial strains are represented by 50 isolates of Staphylococcus. The bacterial strains were analyzed using polymerase chain reaction to identify the nuc, tuf, tst, sea, pathogenic activity genes. After this, the bacteria were tested for ermA, ermB, ermC genes and for mecA, femA which are involved in resistance to macrolides, lincosamides, streptogramin B and to beta-lactams, respectively. The presence or the absence of these genes confirms that tested strains are resistant to specific antibiotic or not. Bacteria pathogenic activity was emphasized by genes as follows: sea (enterotoxin which was found at all isolates, tst (toxic shock toxin gene was not detected in any of isolates and tuf gene (elongation factor was obtained with one pair of primers. Resistance to beta-lactams was evidenced by the presence of mecA in all isolates and femA in some strains. Each of ermC, ermA and ermB, macrolides-lincosamides-streptogramin B resistance genes, were detected.

Resistência a β-lactâmicos em Acinetobacter spp isolados de efluente hospitalar no sul do Brasil Resistance to β-lactams among Acinetobacter spp isolated from hospital sewage in southern Brazil

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Carolina de Souza Gusatti

2009-04-01

Full Text Available Acinetobacter spp é um importante patógeno causador de infecções nosocomiais que acomete pacientes imunocomprometidos e capaz de adquirir resistência a antimicrobianos com facilidade. Os esgotos hospitalares são importantes disseminadores de genes de resistência a antimicrobianos para a microbiota ambiental. Neste contexto, 30 cepas de Acinetobacter spp provenientes de efluente de um hospital em Porto Alegre, RS, foram analisados quanto ao perfil de susceptibilidade a β-lactamases, quinolonas e aminoglicosídeos através de antibiograma e testes de triagem para metalo beta-lactamases e β-lactamases de espectro estendido. O perfil encontrado revela cepas multi-resistentes e que mecanismos de resistência como a produção de β-lactamases de espectro estendido e bombas de efluxo podem estar presentes nesses isolados.Acinetobacter spp is an important pathogen that is responsible for nosocomial infections affecting immunocompromised patients, and it can easily acquire resistance to antimicrobial agents. Hospital sewage is an important means for disseminating genes for resistance to antimicrobial agents, to the microbiota of the environment. Within this context, 30 strains of Acinetobacter spp from the sewage of a hospital in Porto Alegre, Rio Grande do Sul, were analyzed regarding their profile of susceptibility to β-lactams, quinolones and aminoglycosides, by means of an antibiogram and tests to screen for metallo-β-lactamases and extended-spectrum β-lactamases. The profile obtained revealed the presence of multidrug-resistant strains and showed that resistance mechanisms such as the production of extended-spectrum β-lactamases and efflux pumps may be present in these strains.

Beta-lactam antibiotic-induced platelet dysfunction: Evidence for irreversible inhibition of platelet activation in vitro and in vivo after prolonged exposure to penicillin

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Burroughs, S.F.; Johnson, G.J.

1990-01-01

beta-Lactam antibiotics cause platelet dysfunction with bleeding complications. Previous in vitro studies documented reversible inhibition of agonist-receptor interaction. This mechanism is inadequate to explain the effect of beta-lactam antibiotics in vivo. Platelet function does not return to normal immediately after drug treatment, implying irreversible inhibition of platelet function. We report here evidence of irreversible platelet functional and biochemical abnormalities after in vitro and in vivo exposure to beta-lactam antibiotics. Irreversible binding of [14C]-penicillin (Pen) occurred in vitro. After 24 hours' in vitro incubation with 10 to 20 mmol/L Pen, or ex vivo after antibiotic treatment, irreversible functional impairment occurred; but no irreversible inhibition of alpha 2 adrenergic receptors, measured with [3H]-yohimbine, or high-affinity thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptors, measured with agonist [3H]-U46619 and antagonist [3H]-SQ29548, occurred. However, low-affinity platelet TXA2/PGH2 receptors were decreased 40% after Pen exposure in vitro or in vivo, indicating irreversible membrane alteration. Two postreceptor biochemical events were irreversibly inhibited in platelets incubated with Pen for 24 hours in vitro or ex vivo after antibiotic treatment. Thromboxane synthesis was inhibited 28.3% to 81.7%. Agonist-induced rises in cytosolic calcium ([Ca2+]i) were inhibited 40.1% to 67.5% in vitro and 26.6% to 52.2% ex vivo. Therefore, Pen binds to platelets after prolonged exposure, resulting in irreversible dysfunction attributable to inhibition of TXA2 synthesis and impairment of the rise in [Ca2+]i. The loss of low-affinity TXA2/PGH2 receptors suggests that the primary site of action of these drugs is on the platelet membrane

Genetic characterization and plasmid replicon typing of ß-lactam resistant Escherichia coli from humans and companion animals in Egypt

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Limited therapeutic options due to antimicrobial resistance (AR) is a major threat to human and animal health worldwide. There is a paucity of information on ß-lactam resistant Esherichia coli isolated from companion animals in developing countries; therefore their zoonotic impact is unknown. This s...

Draft genome sequence of Pantoea agglomerans JM1, a strain isolated from soil polluted by industrial production of Beta-Lactam antibiotics that exhibits valacyclovir-like hydrolase activity

Czech Academy of Sciences Publication Activity Database

Zahradník, Jiří; Plačková, Martina; Palyzová, Andrea; Marešová, Helena; Kyslíková, Eva; Kyslík, Pavel

2017-01-01

Roč. 5, č. 38 (2017), č. článku e00921-17. ISSN 2169-8287 Institutional support: RVO:61388971 Keywords : 6 nitro 3 (phenylacetamido)benzoic acid * beta lactam antibiotic * topoisomerase (ATP hydrolysing) B Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology

Risk of surgical site infection, acute kidney injury, and Clostridium difficile infection following antibiotic prophylaxis with vancomycin plus a beta-lactam versus either drug alone: A national propensity-score-adjusted retrospective cohort study.

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Branch-Elliman, Westyn; Ripollone, John E; O'Brien, William J; Itani, Kamal M F; Schweizer, Marin L; Perencevich, Eli; Strymish, Judith; Gupta, Kalpana

2017-07-01

The optimal regimen for perioperative antimicrobial prophylaxis is controversial. Use of combination prophylaxis with a beta-lactam plus vancomycin is increasing; however, the relative risks and benefits associated with this strategy are unknown. Thus, we sought to compare postoperative outcomes following administration of 2 antimicrobials versus a single agent for the prevention of surgical site infections (SSIs). Potential harms associated with combination regimens, including acute kidney injury (AKI) and Clostridium difficile infection (CDI), were also considered. Using a multicenter, national Veterans Affairs (VA) cohort, all patients who underwent cardiac, orthopedic joint replacement, vascular, colorectal, and hysterectomy procedures during the period from 1 October 2008 to 30 September 2013 and who received planned manual review of perioperative antimicrobial prophylaxis regimen and manual review for the 30-day incidence of SSI were included. Using a propensity-adjusted log-binomial regression model stratified by type of surgical procedure, the association between receipt of 2 antimicrobials (vancomycin plus a beta-lactam) versus either single agent alone (vancomycin or a beta-lactam) and SSI was evaluated. Measures of association were adjusted for age, diabetes, smoking, American Society of Anesthesiologists score, preoperative methicillin-resistant Staphylococcus aureus (MRSA) status, and receipt of mupirocin. The 7-day incidence of postoperative AKI and 90-day incidence of CDI were also measured. In all, 70,101 procedures (52,504 beta-lactam only, 5,089 vancomycin only, and 12,508 combination) with 2,466 (3.5%) SSIs from 109 medical centers were included. Among cardiac surgery patients, combination prophylaxis was associated with a lower incidence of SSI (66/6,953, 0.95%) than single-agent prophylaxis (190/12,834, 1.48%; crude risk ratio [RR] 0.64, 95% CI 0.49, 0.85; adjusted RR 0.61, 95% CI 0.46, 0.83). After adjusting for SSI risk, no association

Risk of surgical site infection, acute kidney injury, and Clostridium difficile infection following antibiotic prophylaxis with vancomycin plus a beta-lactam versus either drug alone: A national propensity-score-adjusted retrospective cohort study.

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Westyn Branch-Elliman

2017-07-01

Full Text Available The optimal regimen for perioperative antimicrobial prophylaxis is controversial. Use of combination prophylaxis with a beta-lactam plus vancomycin is increasing; however, the relative risks and benefits associated with this strategy are unknown. Thus, we sought to compare postoperative outcomes following administration of 2 antimicrobials versus a single agent for the prevention of surgical site infections (SSIs. Potential harms associated with combination regimens, including acute kidney injury (AKI and Clostridium difficile infection (CDI, were also considered.Using a multicenter, national Veterans Affairs (VA cohort, all patients who underwent cardiac, orthopedic joint replacement, vascular, colorectal, and hysterectomy procedures during the period from 1 October 2008 to 30 September 2013 and who received planned manual review of perioperative antimicrobial prophylaxis regimen and manual review for the 30-day incidence of SSI were included. Using a propensity-adjusted log-binomial regression model stratified by type of surgical procedure, the association between receipt of 2 antimicrobials (vancomycin plus a beta-lactam versus either single agent alone (vancomycin or a beta-lactam and SSI was evaluated. Measures of association were adjusted for age, diabetes, smoking, American Society of Anesthesiologists score, preoperative methicillin-resistant Staphylococcus aureus (MRSA status, and receipt of mupirocin. The 7-day incidence of postoperative AKI and 90-day incidence of CDI were also measured. In all, 70,101 procedures (52,504 beta-lactam only, 5,089 vancomycin only, and 12,508 combination with 2,466 (3.5% SSIs from 109 medical centers were included. Among cardiac surgery patients, combination prophylaxis was associated with a lower incidence of SSI (66/6,953, 0.95% than single-agent prophylaxis (190/12,834, 1.48%; crude risk ratio [RR] 0.64, 95% CI 0.49, 0.85; adjusted RR 0.61, 95% CI 0.46, 0.83. After adjusting for SSI risk, no

Identification of aminoglycoside and β-lactam resistance genes from within an infant gut functional metagenomic library.

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Fiona Fouhy

Full Text Available The infant gut microbiota develops rapidly during the first 2 years of life, acquiring microorganisms from diverse sources. During this time, significant opportunities exist for the infant to acquire antibiotic resistant bacteria, which can become established and constitute the infant gut resistome. With increased antibiotic resistance limiting our ability to treat bacterial infections, investigations into resistance reservoirs are highly pertinent. This study aimed to explore the nascent resistome in antibiotically-naïve infant gut microbiomes, using a combination of metagenomic approaches. Faecal samples from 22 six-month-old infants without previous antibiotic exposure were used to construct a pooled metagenomic library, which was functionally screened for ampicillin and gentamicin resistance. Our library of ∼220Mb contained 0.45 ampicillin resistant hits/Mb and 0.059 gentamicin resistant hits/Mb. PCR-based analysis of fosmid clones and uncloned metagenomic DNA, revealed a diverse and abundant aminoglycoside and β-lactam resistance reservoir within the infant gut, with resistance determinants exhibiting homology to those found in common gut inhabitants, including Escherichia coli, Enterococcus sp., and Clostridium difficile, as well as to genes from cryptic environmental bacteria. Notably, the genes identified differed from those revealed when a sequence-driven PCR-based screen of metagenomic DNA was employed. Carriage of these antibiotic resistance determinants conferred substantial, but varied (2-512x, increases in antibiotic resistance to their bacterial host. These data provide insights into the infant gut resistome, revealing the presence of a varied aminoglycoside and β-lactam resistance reservoir even in the absence of selective pressure, confirming the infant resistome establishes early in life, perhaps even at birth.

Looking for the new preparations for antibacterial therapy. II. Clinical trials; new beta-lactam antibiotics and beta-lactamase inhibitors.

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Karpiuk, Izabela; Tyski, Stefan

2013-01-01

To obtain a status of a medicinal product, a compound possessing potential antimicrobial activity and displaying no cytotoxicity, must undergo three phases of clinical trials to prove its therapeutic efficacy, safety and quality. Properties of the compound should be based on the results of studies meeting specific criteria. Studies should be: randomized, double-blind, involving sufficient number of volunteers, concerning the infections localized in strictly defined area and caused by identified microorganisms. After the medicinal product is authorized to be on the market, clinical trials of the fourth phase are carried out to detect adverse effects, overdose symptoms, interactions of the new drug with other medicinal products and to establish characteristic of activity among groups such as children, elderly, women in pregnancy and patients suffering from other diseases, but only if the benefits of receiving treatment outweigh the risks. This article is a second part of the series associated with searching for new antibacterial agents and it relates to performance of clinical trials and the new compounds belonging to the class of beta-lactams. Among the 9 presented compounds, candidates to become medicinal products, two belong to the cephalosporins (CXA-101, S-649266), one to carbapenems (razupenem), three to monobactams (BAL30072, BAL30376, MC-1) and three to beta-lactamase inhibitors (NXL-104, MK-7655, ME1071).

Cordioxime: a new dioxime gamma-lactam from Cordia platythyrsa.

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Christelle, Tsague Dongmo; Hussainb, Hidayat; Dongo, Etienne; Julius, Oben Enyong; Hussain, Javid

2011-08-01

Cordia platythyrsa Baker is known for its medicinal value. This paper deals with a phytochemical investigation of this species, from which cordioxime (1), a new dioxime y-lactam has been isolated. Its structure was determined by comprehensive analyses of its 1H and 13C NMR, COSY, HMQC, and HMBC spectroscopic, and HREIMS data. The remaining two known compounds were identified as beta-sitosterol, and beta-sitosterol glucopyranoside.

Profiles of phenotype resistance to antibiotic other than β-lactams in Klebsiella pneumoniae ESBLs-producers, carrying blaSHV genes

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Pawel Sacha

2010-04-01

Full Text Available Extended spectrum β-lactamases production is one of the most common mechanism of resistance to extendedspectrum β-lactam antibiotics is increasing worldwide. Twenty five strains of Klebsiella pneumoniae isolated from clinicalspecimens were tested. Based on the phenotypic confirmatory test all these strains were defined as ESBL producers namedESBL(+. The plasmid DNA from each strains was used to investigate the presence of blaSHV genes responsible for extendedspectrum β-lactamases production. Moreover, susceptibility of these strains to antibiotic other than β-lactams in was tested.

The prevalence of nosocomial infections caused by Enterobacter cloacae and antibiotic resistant patterns in samples isolated from patients in two hospitals in Tehran

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Rahbar M

2012-06-01

Conclusion: This study clearly showed the high prevalence of resistance to broad-spectrum beta-lactam antibiotics in the isolated E. cloacae among which 5% were multi drug resistant. All the isolated E. cloacae were susceptible to Colistin. These results can be alarming for physicians treating resistant E. cloacae infections, especially extended-spectrum beta-lactamase producing species.

Phenotypic detection of beta-lactamases production in enterobacteriaceae

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Ćirković Ivana

2014-01-01

Full Text Available Introduction. Beta-lactam antibiotics are the most commonly used antibacterial drugs. However, many bacteria have developed resistance to these antibiotics, and the most common form of resistance is the production of beta-lactamase enzymes. Many members of the Enterobacteriaceae family produce different types of these enzymes. Objective. The aim of this study was to perform phenotypic detection of production and identification of beta-lactamase type in Enterobacteriaceae isolated from different clinical specimens from patients hospitalized in the Clinical Center of Serbia. Methods. The strains of Enterobacteriaceae were collected between November 2011 and January 2012 in the laboratory of the Clinical Center of Serbia. The isolates were identified according to the standard microbiology procedures and confirmed by the Vitek2 automated system. Antimicrobial susceptibility testing was performed by the disk diffusion method, and the phenotypic detection of production and identification of betalactamases was performed according to previously described methodologies. Results. In this study, a total of 172 Enterobacteriaceae strains were isolated. Further testing was performed on 54/145 (37.2% strains showing decreased susceptibility to beta-lactam antibiotics: 13/85 (15.3% Escherichia coli, 31/46 (67.4% Klebsiella pneumoniae and 10/14 (71.4% Proteus mirabilis. Among them, 40/145 (27.6% strains produced extended spectrum betalactamases (ESBLs, 9/145 (6.2% - AmpC, 1/145 (0.7% - K1 beta-lactamase and 4/145 (2.8% - carbapenemases. Carbapenemases were predominantly detected in K. pneumoniae (75%. Conclusion. Enterobacteriaceae produce different types of betalactamases, and the most common type in our study was ESBLs. Production of carbapenemases detected in Enterobacteriaceae is also an associated problem. [Projekat Ministarstva nauke Republike Srbije, br. ON 175039

Comparison of beta-lactam regimens for the treatment of gram-negative pulmonary infections in the intensive care unit based on pharmacokinetics/pharmacodynamics.

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Burgess, David S; Frei, Christopher R

2005-11-01

This study utilized pharmacokinetics/pharmacodynamics to compare beta-lactam regimens for the empirical and definitive treatment of gram-negative pulmonary infections in the ICU. Susceptibility data were extracted from the 2002 Intensive Care Unit Surveillance System (ISS) and pharmacokinetic parameters were obtained from published human studies. Monte Carlo simulation was used to model the free percent time above the MIC (free %T > MIC) for 18 beta-lactam regimens against all gram-negative isolates, Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii. The cumulative fraction of response (CFR) was determined for bacteriostatic and bactericidal targets (free %T > MIC): penicillins (> or = 30/50%), cephalosporins/monobactams (> or = 40/70%) and carbapenems (> or = 20/40%). The 2002 ISS database contained MICs for 2408 gram-negative isolates including 1430 Enterobacteriaceae, 799 P. aeruginosa, and 179 A. baumannii. Imipenem had the highest percentage susceptible for all gram-negatives, Enterobacteriaceae and A. baumannii, while piperacillin/tazobactam had the highest percentage susceptible for P. aeruginosa. For empirical therapy, imipenem 0.5 g every 6 h, cefepime 2 g every 8 h and ceftazidime 2 g every 8 h demonstrated the highest CFR. For definitive therapy, imipenem 0.5 g every 6 h, ertapenem 1 g daily and cefepime 2 g every 8 h, cefepime 1 g every 8 h and cefepime 1 g every 12 h had the highest bactericidal CFR against Enterobacteriaceae; ceftazidime 2 g every 8 h, cefepime 2 g every 8 h, piperacillin/tazobactam 3.375 g every 4 h, ceftazidime 1 g every 8 h and aztreonam 1 g every 8 h against P. aeruginosa; and imipenem 0.5 g every 6 h, ticarcillin/clavulanate 3.1 g every 4 h, ceftazidime 2 g every 8 h, cefepime 2 g every 8 h and ticarcillin/clavulanate 3.1 g every 6 h against A. baumannii. Based on pharmacokinetics/pharmacodynamics, imipenem 0.5 g every 6 h, cefepime 2 g every 8 h and ceftazidime 2 g every 8 h should be the preferred beta-lactam

Genomic Analysis of a Pan-Resistant Isolate of Klebsiella pneumoniae, United States 2016.

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de Man, Tom J B; Lutgring, Joseph D; Lonsway, David R; Anderson, Karen F; Kiehlbauch, Julia A; Chen, Lei; Walters, Maroya Spalding; Sjölund-Karlsson, Maria; Rasheed, J Kamile; Kallen, Alexander; Halpin, Alison Laufer

2018-04-03

Antimicrobial resistance is a threat to public health globally and leads to an estimated 23,000 deaths annually in the United States alone. Here, we report the genomic characterization of an unusual Klebsiella pneumoniae , nonsusceptible to all 26 antibiotics tested, that was isolated from a U.S. The isolate harbored four known beta-lactamase genes, including plasmid-mediated bla NDM-1 and bla CMY-6 , as well as chromosomal bla CTX-M-15 and bla SHV-28 , which accounted for resistance to all beta-lactams tested. In addition, sequence analysis identified mechanisms that could explain all other reported nonsusceptibility results, including nonsusceptibility to colistin, tigecycline, and chloramphenicol. Two plasmids, IncA/C2 and IncFIB, were closely related to mobile elements described previously and isolated from Gram-negative bacteria from China, Nepal, India, the United States, and Kenya, suggesting possible origins of the isolate and plasmids. This is one of the first K. pneumoniae isolates in the United States to have been reported to the Centers for Disease Control and Prevention (CDC) as nonsusceptible to all drugs tested, including all beta-lactams, colistin, and tigecycline. IMPORTANCE Antimicrobial resistance is a major public health threat worldwide. Bacteria that are nonsusceptible or resistant to all antimicrobials available are of major concern to patients and the public because of lack of treatment options and potential for spread. A Klebsiella pneumoniae strain that was nonsusceptible to all tested antibiotics was isolated from a U.S. Mechanisms that could explain all observed phenotypic antimicrobial resistance phenotypes, including resistance to colistin and beta-lactams, were identified through whole-genome sequencing. The large variety of resistance determinants identified demonstrates the usefulness of whole-genome sequencing for detecting these genes in an outbreak response. Sequencing of isolates with rare and unusual phenotypes can provide

Oral Gram-negative anaerobic bacilli as a reservoir of β-lactam resistance genes facilitating infections with multiresistant bacteria.

Science.gov (United States)

Dupin, Clarisse; Tamanai-Shacoori, Zohreh; Ehrmann, Elodie; Dupont, Anais; Barloy-Hubler, Frédérique; Bousarghin, Latifa; Bonnaure-Mallet, Martine; Jolivet-Gougeon, Anne

2015-02-01

Many β-lactamases have been described in various Gram-negative bacilli (Capnocytophaga, Prevotella, Fusobacterium, etc.) of the oral cavity, belonging to class A of the Ambler classification (CepA, CblA, CfxA, CSP-1 and TEM), class B (CfiA) or class D in Fusobacterium nucleatum (FUS-1). The minimum inhibitory concentrations of β-lactams are variable and this variation is often related to the presence of plasmids or other mobile genetic elements (MGEs) that modulate the expression of resistance genes. DNA persistence and bacterial promiscuity in oral biofilms also contribute to genetic transformation and conjugation in this particular microcosm. Overexpression of efflux pumps is facilitated because the encoding genes are located on MGEs, in some multidrug-resistant clinical isolates, similar to conjugative transposons harbouring genes encoding β-lactamases. All these facts lead us to consider the oral cavity as an important reservoir of β-lactam resistance genes and a privileged place for genetic exchange, especially in commensal strictly anaerobic Gram-negative bacilli. Copyright © 2014 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Quantitative assessment of faecal shedding of β-lactam-resistant Escherichia coli and enterococci in dogs

DEFF Research Database (Denmark)

Gongora, Carmen Espinosa; Shah, Syed Qaswar Ali; Jessen, Lisbeth Rem

2015-01-01

Quantitative data on faecal shedding of antimicrobial resistant bacteria are crucial to assess the risk of transmission from dogs to other animals as well as humans. In this study we investigated prevalence and concentrations of β-lactam-resistant Escherichia coli and enterococci in the faeces...... of 108 dogs presenting at a veterinary hospital in Denmark. The dogs had not been treated with antimicrobials for 4 weeks prior to the study. Total E. coli and enterococci were quantified by counts on MacConkey and Slanetz-Bartley, respectively. Resistant E. coli and enterococci were counted on the same...... media containing relevant antibiotic concentrations, followed by species identification using MALDI-TOF. Ampicillin- and cefotaxime-resistant E. coli were detected in 40% and 8% of the dogs, respectively, whereas approximately 15% carried ampicillin-resistant enterococci, mainly Enterococcus faecium...

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

Science.gov (United States)

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

Development of a miniaturised microarray-based assay for the rapid identification of antimicrobial resistance genes in Gram-negative bacteria

DEFF Research Database (Denmark)

Batchelor, Miranda; Hopkins, Katie L; Liebana, Ernesto

2008-01-01

We describe the development of a miniaturised microarray for the detection of antimicrobial resistance genes in Gram-negative bacteria. Included on the array are genes encoding resistance to aminoglycosides, trimethoprim, sulphonamides, tetracyclines and beta-lactams, including extended-spectrum ...

Cloning and sequence of the gene encoding a cefotaxime-hydrolyzing class A beta-lactamase isolated from Escherichia coli.

Science.gov (United States)

Ishii, Y; Ohno, A; Taguchi, H; Imajo, S; Ishiguro, M; Matsuzawa, H

1995-01-01

Escherichia coli TUH12191, which is resistant to piperacillin, cefazolin, cefotiam, ceftizoxime, cefuzonam, and aztreonam but is susceptible to cefoxitin, latamoxef, flomoxef, and imipenem, was isolated from the urine of a patient treated with beta-lactam antibiotics. The beta-lactamase (Toho-1) purified from the bacteria had a pI of 7.8, had a molecular weight of about 29,000, and hydrolyzed beta-lactam antibiotics such as penicillin G, ampicillin, oxacillin, carbenicillin, piperacillin, cephalothin, cefoxitin, cefotaxime, ceftazidime, and aztreonam. Toho-1 was markedly inhibited by beta-lactamase inhibitors such as clavulanic acid and tazobactam. Resistance to beta-lactams, streptomycin, spectinomycin, sulfamethoxazole, and trimethoprim was transferred by conjugational transfer from E. coli TUH12191 to E. coli ML4903, and the transferred plasmid was about 58 kbp, belonging to incompatibility group M. The cefotaxime resistance gene for Toho-1 was subcloned from the 58-kbp plasmid by transformation of E. coli MV1184. The sequence of the gene for Toho-1 was determined, and the open reading frame of the gene consisted of 873 or 876 bases (initial sequence, ATGATG). The nucleotide sequence of the gene (DDBJ accession number D37830) was found to be about 73% homologous to the sequence of the gene encoding a class A beta-lactamase produced by Klebsiella oxytoca E23004. According to the amino acid sequence deduced from the DNA sequence, the precursor consisted of 290 or 291 amino acid residues, which contained amino acid motifs common to class A beta-lactamases (70SXXK, 130SDN, and 234KTG). Toho-1 was about 83% homologous to the beta-lactamase mediated by the chromosome of K. oxytoca D488 and the beta-lactamase mediated by the plasmid of E. coli MEN-1. Therefore, the newly isolated beta-lactamase Toho-1 produced by E. coli TUH12191 is similar to beta-lactamases produced by K. oxytoca D488, K. oxytoca E23004, and E. coli MEN-1 rather than to mutants of TEM or SHV enzymes

Heavy metals in liquid pig manure in light of bacterial antimicrobial resistance

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Hoelzel, Christina S., E-mail: Christina.Hoelzel@wzw.tum.de [Chair of Animal Hygiene, Technische Universitaet Muenchen, Weihenstephaner Berg 3, 85354 Freising (Germany); Mueller, Christa [Institute for Agroecology, Organic Farming and Soil Protection, Bavarian State Research Center for Agriculture (LfL), Lange Point 12, 85354 Freising (Germany); Harms, Katrin S. [Chair of Animal Hygiene, Technische Universitaet Muenchen, Weihenstephaner Berg 3, 85354 Freising (Germany); Mikolajewski, Sabine [Department for Quality Assurance and Analytics, Bavarian State Research Center for Agriculture (LfL), Lange Point 4, 85354 Freising (Germany); Schaefer, Stefanie; Schwaiger, Karin; Bauer, Johann [Chair of Animal Hygiene, Technische Universitaet Muenchen, Weihenstephaner Berg 3, 85354 Freising (Germany)

2012-02-15

Heavy metals are regularly found in liquid pig manure, and might interact with bacterial antimicrobial resistance. Concentrations of heavy metals were determined by atomic spectroscopic methods in 305 pig manure samples and were connected to the phenotypic resistance of Escherichia coli (n=613) against 29 antimicrobial drugs. Concentrations of heavy metals (/kg dry matter) were 0.08-5.30 mg cadmium, 1.1-32.0 mg chrome, 22.4-3387.6 mg copper, <2.0-26.7 mg lead, <0.01-0.11 mg mercury, 3.1-97.3 mg nickel and 93.0-8239.0 mg zinc. Associated with the detection of copper and zinc, resistance rates against {beta}-lactams were significantly elevated. By contrast, the presence of mercury was significantly associated with low antimicrobial resistance rates of Escherichia coli against {beta}-lactams, aminoglycosides and other antibiotics. Effects of subinhibitory concentrations of mercury on bacterial resistance against penicillins, cephalosporins, aminoglycosides and doxycycline were also demonstrated in a laboratory trial. Antimicrobial resistance in the porcine microflora might be increased by copper and zinc. By contrast, the occurrence of mercury in the environment might, due to co-toxicity, act counter-selective against antimicrobial resistant strains.

Development of a novel and automated fluorescent immunoassay for the analysis of beta-lactam antibiotics

NARCIS (Netherlands)

Benito-Pena, E.; Moreno-Bondi, M.C.; Orellana, G.; Maquieira, K.; Amerongen, van A.

2005-01-01

An automated immunosensor for the rapid and sensitive analysis of penicillin type -lactam antibiotics has been developed and optimized. An immunogen was prepared by coupling the common structure of the penicillanic -lactam antibiotics, i.e., 6-aminopenicillanic acid to keyhole limpet hemocyanin.

A response regulator from a soil metagenome enhances resistance to the β-lactam antibiotic carbenicillin in Escherichia coli.

Directory of Open Access Journals (Sweden)

Heather K Allen

Full Text Available Functional metagenomic analysis of soil metagenomes is a method for uncovering as-yet unidentified mechanisms for antibiotic resistance. Here we report an unconventional mode by which a response regulator derived from a soil metagenome confers resistance to the β-lactam antibiotic carbenicillin in Escherichia coli. A recombinant clone (βlr16 harboring a 5,169 bp DNA insert was selected from a metagenomic library previously constructed from a remote Alaskan soil. The βlr16 clone conferred specific resistance to carbenicillin, with limited increases in resistance to other tested antibiotics, including other β-lactams (penicillins and cephalosporins, rifampin, ciprofloxacin, erythromycin, chloramphenicol, nalidixic acid, fusidic acid, and gentamicin. Resistance was more pronounced at 24°C than at 37°C. Zone-of-inhibition assays suggested that the mechanism of carbenicillin resistance was not due to antibiotic inactivation. The DNA insert did not encode any genes known to confer antibiotic resistance, but did have two putative open reading frames (ORFs that were annotated as a metallopeptidase and a two-component response regulator. Transposon mutagenesis and subcloning of the two ORFs followed by phenotypic assays showed that the response regulator gene was necessary and sufficient to confer the resistance phenotype. Quantitative reverse transcriptase PCR showed that the response regulator suppressed expression of the ompF porin gene, independently of the small RNA regulator micF, and enhanced expression of the acrD, mdtA, and mdtB efflux pump genes. This work demonstrates that antibiotic resistance can be achieved by the modulation of gene regulation by heterologous DNA. Functional analyses such as these can be important for making discoveries in antibiotic resistance gene biology and ecology.

Mechanisms of methicillin resistance in Staphylococcus aureus and methods for laboratory detection.

Science.gov (United States)

Jorgensen, J H

1991-01-01

Three distinctly different mechanisms of methicillin resistance have been described in Staphylococcus aureus. The best-documented and probably most important mechanism is production of a unique, low affinity penicillin-binding protein, PBP 2a. Strains possessing PBP 2a are resistant to methicillin, oxacillin, and probably all other currently available beta-lactam antibiotics. Two additional mechanisms of reduced susceptibility to methicillin have been described. Borderline resistance (BORSA) to the semi-synthetic penicillins has been attributed to the hyperproduction of normal staphylococcal beta-lactamase. A third mechanism has recently been advanced that describes an intermediate level of resistance to methicillin due to production of modified, normal PBPs with reduced affinity for beta-lactams (MODSA). Little is known regarding the prevalence or clinical significance of the BORSA and MODSA strains. The most reliable in vitro susceptibility test methods for detecting MRSA (strains possessing PBP 2a) include the microdilution minimum inhibitory concentration (MIC) test (with 2% NaCl supplemented broth), the oxacillin agar screen plate test (incorporating 6 micrograms/ml oxacillin in 4% NaCl supplemented agar), and the National Committee for Clinical Laboratory Standards (NCCLS) disk diffusion test with oxacillin. All three methods use direct inoculum preparation and incubation of tests at 35 degrees C for a full 24 hours.

Detection of Extended Spectrum Beta-Lactamases Resistance Genes among Bacteria Isolated from Selected Drinking Water Distribution Channels in Southwestern Nigeria.

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Adesoji, Ayodele T; Ogunjobi, Adeniyi A

2016-01-01

Extended Spectrum Beta-Lactamases (ESBL) provide high level resistance to beta-lactam antibiotics among bacteria. In this study, previously described multidrug resistant bacteria from raw, treated, and municipal taps of DWDS from selected dams in southwestern Nigeria were assessed for the presence of ESBL resistance genes which include bla TEM, bla SHV, and bla CTX by PCR amplification. A total of 164 bacteria spread across treated (33), raw (66), and municipal taps (68), belonging to α-Proteobacteria, β-Proteobacteria, γ-Proteobacteria, Flavobacteriia, Bacilli, and Actinobacteria group, were selected for this study. Among these bacteria, the most commonly observed resistance was for ampicillin and amoxicillin/clavulanic acid (61 isolates). Sixty-one isolates carried at least one of the targeted ESBL genes with bla TEM being the most abundant (50/61) and bla CTX being detected least (3/61). Klebsiella was the most frequently identified genus (18.03%) to harbour ESBL gene followed by Proteus (14.75%). Moreover, combinations of two ESBL genes, bla SHV + bla TEM or bla CTX + bla TEM, were observed in 11 and 1 isolate, respectively. In conclusion, classic bla TEM ESBL gene was present in multiple bacterial strains that were isolated from DWDS sources in Nigeria. These environments may serve as foci exchange of genetic traits in a diversity of Gram-negative bacteria.

[Beta-lactamic antibiotics allergy in cataract surgery. Prevalence and preoperative characteristics of allergic patients].

Science.gov (United States)

Fernández-Rubio, M E; Cuesta-Rodríguez, T; Urcelay-Segura, J L; Cortés-Valdés, C

2014-03-01

To describe the proportion of patients allergic to β-lactam antibiotics and the prevalence of preoperative conjunctival bacteria among those undergoing cataract surgery in our area. Retrospective cross-sectional study of prevalence of β-lactam allergic patients consecutively scheduled for cataract surgery from 11 July 2005 to November 2012. For studying the prevalence of conjunctival bacteria and clinical characteristics in the patients' preoperative examination, those under 18 years and those with cataract surgery combined with other eye surgeries were excluded. Data from the first preoperative examination of the remaining patients were selected. Clinical data were extracted from the database generated in the evaluation made for anesthetic purposes, and the microbiological data from the laboratory database. Both bases were linked through a patient history code. A comparison was made between the prevalence of conjunctival bacteria and clinical characteristics in allergic and non-allergic patients. From 12,409 adults selected for the bacteriological study, 862 (6.96%) were allergic to β-lactams, their mean age (74.45 years) was higher than that of the non-allergic (P=.005). The proportion of women (71.4%) in the allergic patient group was much higher than that of men. The prevalence of pathogenic bacteria (especially Bacillus spp and Pseudomonas aeruginosa), lung disease and heart failure, was higher in allergic patients. The prevalence of allergy to β-lactams in this study is within the range described in other populations. The higher prevalence of pathogenic bacteria and the predominance of women in those allergic to β-lactams are useful data to guide their surgical prophylaxis. Copyright © 2013 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

Comparison of multilocus sequence typing, RAPD, and MALDI-TOF mass spectrometry for typing of β-lactam-resistant Klebsiella pneumoniae strains.

Science.gov (United States)

Sachse, Svea; Bresan, Stephanie; Erhard, Marcel; Edel, Birgit; Pfister, Wolfgang; Saupe, Angela; Rödel, Jürgen

2014-12-01

Extended spectrum of β-lactam (ESBL) resistance of Klebsiella pneumoniae has become an increasing problem in hospital infections. Typing of isolates is important to establish the intrahospital surveillance of resistant clones. In this study, the discriminatory potential of randomly amplified polymorphic DNA and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) analyses were compared with multilocus sequence typing (MLST) by using 17 β-lactam-resistant K. pneumoniae isolates of different genotypes. MLST alleles were distributed in 8 sequence types (STs). Among ESBL strains of the same ST, the presence of different β-lactamase genes was common. RAPD band patterns also revealed 8 types that corresponded to MLST-defined genotypes in 15 out of 17 cases. MALDI-TOF analysis could differentiate 5 clusters of strains. The results of this work show that RAPD may be usable as a rapid screening method for the intrahospital surveillance of K. pneumoniae, allowing a discrimination of clonally related strains. MALDI-TOF-based typing was not strongly corresponding to genotyping and warrants further investigation. Copyright © 2014 Elsevier Inc. All rights reserved.

Resistance to antimicrobials and biofilm formation in Staphylococcus spp. isolated from bovine mastitis in the Northeast of Brazil.

Science.gov (United States)

da Costa Krewer, Carina; Santos Amanso, Evandro; Veneroni Gouveia, Gisele; de Lima Souza, Renata; da Costa, Mateus Matiuzzi; Aparecido Mota, Rinaldo

2015-03-01

Mastitis is the principal disease affecting dairy herds worldwide. The aim of the present study was to characterize phenotypic and genotypic features associated with resistance to antimicrobials in Staphylococcus spp. isolated from 2064 milk samples of 525 lactating cows in the Northeast of Brazil. Of the 218 isolates analyzed, 57.8% were characterized as Staphylococcus aureus, 28% as coagulase-positive staphylococci other than S. aureus (oCPS), and 14.2% as coagulase-negative staphylococci (CNS). The test for susceptibility to antimicrobials showed amoxicillin (32.6%) to be the less effective drug in vitro, and the multi-drug resistance (MDR) rate for beta-lactams varied from 0 to 0.75. The genotypic characterization showed that 93.1% of the samples were tested positive for the blaZ gene, while none amplified mecA. The antibiotic efflux mechanism was observed in 0.9% of isolates. The biofilm formation was found in 3.7 and 96.3% of samples, respectively, on Congo red agar and on the microplate adhesion test, while the icaD gene was present in 92.2% of Staphylococcus spp. The high frequency of blaZ gene observed in this study was associated with the resistance of most Staphylococcus spp. to one or more of the beta-lactams tested, which are routinely used in Brazilian herds for mastitis treatment. The biofilm formation was also detected in the isolates analyzed being an important characteristic for pathogenicity and antimicrobial resistance of bacteria.

Staphylococcal phenotypes induced by naturally occurring and synthetic membrane-interactive polyphenolic β-lactam resistance modifiers.

Directory of Open Access Journals (Sweden)

Lucia Palacios

Full Text Available Galloyl catechins, in particular (--epicatechin gallate (ECg, have the capacity to abrogate β-lactam resistance in methicillin-resistant strains of Staphylococcus aureus (MRSA; they also prevent biofilm formation, reduce the secretion of a large proportion of the exoproteome and induce profound changes to cell morphology. Current evidence suggests that these reversible phenotypic traits result from their intercalation into the bacterial cytoplasmic membrane. We have endeavoured to potentiate the capacity of ECg to modify the MRSA phenotype by stepwise removal of hydroxyl groups from the B-ring pharmacophore and the A:C fused ring system of the naturally occurring molecule. ECg binds rapidly to the membrane, inducing up-regulation of genes responsible for protection against cell wall stress and maintenance of membrane integrity and function. Studies with artificial membranes modelled on the lipid composition of the staphylococcal bilayer indicated that ECg adopts a position deep within the lipid palisade, eliciting major alterations in the thermotropic behaviour of the bilayer. The non-galloylated homolog (--epicatechin enhanced ECg-mediated effects by facilitating entry of ECg molecules into the membrane. ECg analogs with unnatural B-ring hydroxylation patterns induced higher levels of gene expression and more profound changes to MRSA membrane fluidity than ECg but adopted a more superficial location within the bilayer. ECg possessed a high affinity for the positively charged staphylococcal membrane and induced changes to the biophysical properties of the bilayer that are likely to account for its capacity to disperse the cell wall biosynthetic machinery responsible for β-lactam resistance. The ability to enhance these properties by chemical modification of ECg raises the possibility that more potent analogs could be developed for clinical evaluation.

In vitro and in vivo efficacy of β-lactams against replicating and slowly growing/nonreplicating Mycobacterium tuberculosis.

Science.gov (United States)

Solapure, Suresh; Dinesh, Neela; Shandil, Radha; Ramachandran, Vasanthi; Sharma, Sreevalli; Bhattacharjee, Deepa; Ganguly, Samit; Reddy, Jitendar; Ahuja, Vijaykamal; Panduga, Vijender; Parab, Manish; Vishwas, K G; Kumar, Naveen; Balganesh, Meenakshi; Balasubramanian, V

2013-06-01

Beta-lactams, in combination with beta-lactamase inhibitors, are reported to have activity against Mycobacterium tuberculosis bacteria growing in broth, as well as inside the human macrophage. We tested representative beta-lactams belonging to 3 different classes for activity against replicating M. tuberculosis in broth and nonreplicating M. tuberculosis under hypoxia, as well as against streptomycin-starved M. tuberculosis strain 18b (ss18b) in the presence or absence of clavulanate. Most of the combinations showed bactericidal activity against replicating M. tuberculosis, with up to 200-fold improvement in potency in the presence of clavulanate. None of the combinations, including those containing meropenem, imipenem, and faropenem, killed M. tuberculosis under hypoxia. However, faropenem- and meropenem-containing combinations killed strain ss18b moderately. We tested the bactericidal activities of meropenem-clavulanate and amoxicillin-clavulanate combinations in the acute and chronic aerosol infection models of tuberculosis in BALB/c mice. Based on pharmacokinetic/pharmacodynamic indexes reported for beta-lactams against other bacterial pathogens, a cumulative percentage of a 24-h period that the drug concentration exceeds the MIC under steady-state pharmacokinetic conditions (%TMIC) of 20 to 40% was achieved in mice using a suitable dosing regimen. Both combinations showed marginal reduction in lung CFU compared to the late controls in the acute model, whereas both were inactive in the chronic model.

A possible role for acetylated intermediates in diaminopimelate and tabtoxinine-beta-lactam biosynthesis in Pseudomonas syringae pv. tabaci BR2.024.

Science.gov (United States)

Liu, L; Shaw, P D

1997-01-01

The deduced product of an open reading frame (ORF3) located in the tabtoxinine-beta-lactam (T beta L) biosynthetic region of Pseudomonas syringae pv. tabaci BR2.024 (BR2.024) has significant sequence homology to the dapD products of other bacteria. dapD encodes L-2,3,4,5-tetrahydrodipicolinate succinyl coenzyme A succinyltransferase (THDPA-ST), an enzyme in the diaminopimelate (DAP) and lysine biosynthetic pathway. Complementation studies, in vitro transcription-translation experiments, and enzymatic assays indicated that ORF3 encodes a product with THDPA-ST activity in Escherichia coli dapD mutant beta 274. However, a BR2.024 mutant with an insert in ORF3 was prototrophic, and only basal THDPA-ST activity was detected in extracts of both parent and mutant. This finding suggested that ORF3 was not required for DAP biosynthesis and that it did not encode a product with THDPA-ST activity. The results of enzymatic studies, indicating that BR2.024 uses acetylated intermediates for DAP biosynthesis, are consistent with the hypothesis that BR2.024 does not need THDPA-ST for DAP biosynthesis. The ORF3 mutant produced reduced levels of tabtoxin, indicating that ORF3 may have a role in T beta L biosynthesis. We have named the gene tabB and have proposed a possible function for the gene product. PMID:9294453

Detection of meca gene from methicillin resistant staphylococcus aureus isolates of north sumatera

Science.gov (United States)

Septiani Nasution, Gabriella; Suryanto, Dwi; Lia Kusumawati, R.

2018-03-01

Methicillin Resistant Staphylococcus aureus (MRSA) is a major pathogen associated with hospital-acquired infections (nosocomial infections). MRSA is a type of S. aureus resistant to the sub-group of beta-lactam antibiotics such as penicillin, cephalosporin, monobactam, and carbapenem. MRSA is resistant because of genetic changes caused by exposure to irrational antibiotic therapy. This study aimed to detect mecA gene in North Sumatra isolates of MRSA and to determine the pattern of antibiotic resistance in S.aureus isolates classified as MRSA by Vitek 2 Compact in the Central Public Hospital Haji Adam Malik, Medan. Samples were 40 isolates of S. aureus classified as MRSA obtained from clinical microbiology specimens. DNA isolation of the isolates was conducted by a method of freeze-thaw cycling. Amplification of mecA gene was done by PCR technique using specific primer for the gene. PCR products were visualized using mini-gel electrophoresis. The results showed that all MRSA isolates showed to have 533 bp band of mecA. Antibiotics test of Vitek 2 Compact showed that despite all isolates were resistant to beta-lactam antibiotics groups; the isolates showed multidrug resistant to other common antibiotics, such as aminoglycosides, macrolides, and fluoroquinolones. However, they were still sensitive to vancomycin (82.5% isolates), linezolid (97.5% isolates), and tigecycline (100% isolates).

In-silico modeling of a novel OXA-51 from β-lactam-resistant Acinetobacter baumannii and its interaction with various antibiotics.

Science.gov (United States)

Tiwari, Vishvanath; Nagpal, Isha; Subbarao, Naidu; Moganty, Rajeswari R

2012-07-01

Acinetobacter baumannii, one of the major Gram negative bacteria, causes nosocomial infections such as pneumonia, urinary tract infection, meningitis, etc. β-lactam-based antibiotics like penicillin are used conventionally to treat infections of A. baumannii; however, they are becoming progressively less effective as the bacterium produces diverse types of β-lactamases to inactivate the antibiotics. We have recently identified a novel β-lactamase, OXA-51 from clinical strains of A. baumannii from our hospital. In the present study, we generated the structure of OXA-51 using MODELLER9v7 and studied the interaction of OXA-51 with a number of β-lactams (penicillin, oxacillin, ceftazidime, aztreonam and imipenem) using two independent programs: GLIDE and GOLD. Based on the results of different binding parameters and number of hydrogen bonds, interaction of OXA-51 was found to be maximum with ceftazidime and lowest with imipenem. Further, molecular dynamics simulation results also support this fact. The lowest binding affinity of imipenem to OXA-51 indicates clearly that it is not efficiently cleaved by OXA-51, thus explaining its high potency against resistant A. baumannii. This finding is supported by experimental results from minimum inhibitory concentration analysis and transmission electron microscopy. It can be concluded that carbapenems (imipenem) are presently effective β-lactam antibiotics against resistant strains of A. baumannii harbouring OXA-51. The results presented here could be useful in designing more effective derivatives of carbapenem.

Extended spectrum beta-lactamases in urinary gram-negative bacilli and their susceptibility pattern

International Nuclear Information System (INIS)

Mumtaz, S.

2008-01-01

Beta-lactamases of gram-negative bacteria are the most important mechanism of resistance against beta lactams. Two types of beta-lactamases can confer resistance against third generation cephalosporins inducible Chromosomal beta -lactamases and extended-spectrum beta-lactamases. The extended-spectrum beta lactamases producing Strains of Enterobacteriaceae have emerged as a major problem in hospitalized as well as community based infections resulting in range of infections from uncomplicated urinary tract infection to life threatening sepsis. The study was conducted at the Microbiology Department of Fauji Foundation Hospital, Rawalpindi over a period of two years (April 2004-March 2006). Multidrug resistance and extended spectrum beta-lactamases production was studied in 111 enteric Gram-negative bacilli isolated from urine of symptomatic patients (1- 70 years) including males and females from indoor and outdoor patients by using double disc diffusion technique. Prevalence of extended-spectrum beta-lactamases production was seen in 71 (61.2%) enteric gram-negative organisms, the most prevalent gram-negative organism was Klebsiella pneumoniae 40 (71.4%) followed by Escherichia coli 27 (62.8%) and Pseudomonas aeruginosa 3 (25%). The extended-spectrum beta-lactamases producers were more prevalent in indoor patients 63 (88.7%) compared to outdoor patients 8 (11.3%), more in females 43 (60.6%) than males, 28 (39.4%). The extended-spectrum beta-lactamases producing gram-negative rods had more antibiotic-resistant profile than non-producers. All enteric gram negative rods should be tested for the production of extended-spectrum beta-lactamases in routine microbiology laboratory. (author)

[Beta lactam antibiotics and the question of dose regimen for severe infection. Prolonged infusion theoretically appealing--yet no evidence of clinical benefit].

Science.gov (United States)

Leander, Gunilla; Eliasson, Erik; Hanberger, Håkan; Giske, Christian

2015-03-24

Patients with severe sepsis/septic shock have a high mortality. Beta-lactam antibiotics are normally first line treatment. This antimicrobial class has been associated with time-dependent efficacy. It is therefore plausible that administration as prolonged infusion will increase the therapeutic effect, as compared to short term bolus injections, which is the most common practice today. We have reviewed 14 randomized controlled studies to investigate whether prolonged infusion provides lower mortality and/or increased clinical cure. In summary, convincing advantages with prolonged infusion could not be found, however randomized studies are heterogeneous, and it cannot be excluded that some subgroups of critically ill patients could benefit from such treatment.

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

DEFF Research Database (Denmark)

Bortolaia, Valeria; Guardabassi, Luca; Bisgaard, Magne

An increased concern for the possible transfer of resistant bacteria or mobile resistance elements from food animals to humans has resulted in rigorous legislation preventing i.e. practical use of fluoroquinolones in the Danish broiler industry (Olesen et al., 2004; Petersen et al., 2006...... and nalidixic acid resistances were detected in all flocks. The numbers of E. coli resistant to these drugs were higher in plates from parent flocks than in those from offspring flocks. A broiler parent flock without any history of quinolone usage tested positive for ciprofloxacin-resistant E. coli, although...... and mutations responsible for these types of resistance. References DANMAP 2005. 2006. Use of antimicrobial agents and occurrence of antimicrobial resistance in bacteria from food animals, foods and humans in Denmark. Danish Veterinary Laboratory, Copenhagen, Denmark, ISSN 1600-2032. Olesen, I., H. Hasman...

Burden of different beta-lactamase classes among clinical isolates of AmpC-producing Pseudomonas aeruginosa in burn patients: A prospective study

OpenAIRE

Kumar, V.; Sen, M. R.; Nigam, C.; Gahlot, R.; Kumari, S.

2012-01-01

Background: Pseudomonas aeruginosa is one of the most common pathogens causing infections in burns, and shows increasing resistance to β-lactam antibiotics by producing different classes of beta-lactamases. It is also not unusual to find a single isolate that expresses multiple β-lactamase enzymes, further complicating the treatment options. Thus, in this study, we aimed to determine the coexistence of different beta-lactamase enzymes in clinical isolates of P. aeruginosa in the burn ward. Ma...

Resistance to β-Lactams in Neisseria ssp Due to Chromosomally Encoded Penicillin-Binding Proteins.

Science.gov (United States)

Zapun, André; Morlot, Cécile; Taha, Muhamed-Kheir

2016-09-28

Neisseria meningitidis and Neisseria gonorrhoeae are human pathogens that cause a variety of life-threatening systemic and local infections, such as meningitis or gonorrhoea. The treatment of such infection is becoming more difficult due to antibiotic resistance. The focus of this review is on the mechanism of reduced susceptibility to penicillin and other β-lactams due to the modification of chromosomally encoded penicillin-binding proteins (PBP), in particular PBP2 encoded by the penA gene. The variety of penA alleles and resulting variant PBP2 enzymes is described and the important amino acid substitutions are presented and discussed in a structural context.

The role of a second-shell residue in modifying substrate and inhibitor interactions in the SHV beta-lactamase: a study of ambler position Asn276.

Science.gov (United States)

Drawz, Sarah M; Bethel, Christopher R; Hujer, Kristine M; Hurless, Kelly N; Distler, Anne M; Caselli, Emilia; Prati, Fabio; Bonomo, Robert A

2009-06-02

Inhibitor-resistant class A beta-lactamases of the TEM and SHV families that arise by single amino acid substitutions are a significant threat to the efficacy of beta-lactam/beta-lactamase inhibitor combinations. To better understand the basis of the inhibitor-resistant phenotype in SHV, we performed mutagenesis to examine the role of a second-shell residue, Asn276. Of the 19 variants expressed in Escherichia coli, only the Asn276Asp enzyme demonstrated reduced susceptibility to ampicillin/clavulanate (MIC increased from 50/2 --> 50/8 microg/mL) while maintaining high-level resistance to ampicillin (MIC = 8192 microg/mL). Steady-state kinetic analyses of Asn276Asp revealed slightly diminished k(cat)/K(m) for all substrates tested. In contrast, we observed a 5-fold increase in K(i) for clavulanate (7.4 +/- 0.9 microM for Asn276Asp vs 1.4 +/- 0.2 microM for SHV-1) and a 40% reduction in k(inact)/K(I) (0.013 +/- 0.002 microM(-1 )s(-1) for Asn276Asp vs 0.021 +/- 0.004 microM(-1) s(-1) for SHV-1). Timed electrospray ionization mass spectrometry of clavulanate-inhibited SHV-1 and SHV Asn276Asp showed nearly identical mass adducts, arguing for a similar pathway of inactivation. Molecular modeling shows that novel electrostatic interactions are formed between Arg244Neta2 and both 276AspOdelta1 and Odelta2; these new forces restrict the spatial position of Arg244, a residue important in the recognition of the C(3)/C(4) carboxylate of beta-lactam substrates and inhibitors. Testing the functional consequences of this interaction, we noted considerable free energy costs (+DeltaDeltaG) for substrates and inhibitors. A rigid carbapenem (meropenem) was most affected by the Asn276Asp substitution (46-fold increase in K(i) vs SHV-1). We conclude that residue 276 is an important second-shell residue in class A beta-lactamase-mediated resistance to substrates and inhibitors, and only Asn is able to precisely modulate the conformational flexibility of Arg244 required for successful

Multidrug-Resistant Escherichia fergusonii: a Case of Acute Cystitis▿

Science.gov (United States)

Savini, Vincenzo; Catavitello, Chiara; Talia, Marzia; Manna, Assunta; Pompetti, Franca; Favaro, Marco; Fontana, Carla; Febbo, Fabio; Balbinot, Andrea; Di Berardino, Fabio; Di Bonaventura, Giovanni; Di Zacomo, Silvia; Esattore, Francesca; D'Antonio, Domenico

2008-01-01

We report a case in which Escherichia fergusonii, an emerging pathogen in various types of infections, was associated with cystitis in a 52-year-old woman. The offending strain was found to be multidrug resistant. Despite in vitro activity, beta-lactam treatment failed because of a lack of patient compliance with therapy. The work confirms the pathogenic potential of E. fergusonii. PMID:18256229

Practical Management of Patients with a History of Immediate Hypersensitivity to Common non-Beta-Lactam Drugs.

Science.gov (United States)

Macy, Eric

2016-01-01

Immediate hypersensitivity reactions to medications are among the most feared adverse drug reactions, because of their close association with anaphylaxis. This review discusses a practical management approach for patients with a history of an immediate hypersensitivity to a non-beta-lactam medication, where reexposure to the implicated, or similar, medication is clinically necessary. Mechanisms associated with severe immediate hypersensitivity reactions include IgE-mediated mast cell activation, complement-mediated mast cell activation, and direct mast cell activation. Immediate hypersensitivity reactions may also be mediated by vasodilators, other pharmacologic mechanisms, or be secondary to underlying patient-specific biochemical abnormalities such as endocrine tumors or chronic spontaneous urticaria. The key features in the reaction history and the biochemistry of the implicated medication are discussed. Most individuals with a history of immediate hypersensitivity to a medication, who require reuse of that drug, can be safely retreated with a therapeutic course of the implicated drug after a full-dose challenge, graded challenge, or desensitization, with or without premedication and/or any preliminary diagnostic testing, depending on the specific situation.

Beta limit of resistive plasma in Torsatron / Heliotron

International Nuclear Information System (INIS)

Itoh, K.; Ichiguchi, K.; Itoh, S.I.

1992-02-01

Stability against the interchange mode in the Torsatron / Heliotron device is investigated, taking into account the effects of the resistivity, current diffusivity, ion viscosity and thermal diffusivity. Critical beta for the low-mode-number stability is found at the finite beta value. For the range of plasma parameters of the present experiments, the resistive mode and current diffusive mode set comparable critical beta values, which are consistent with experimental observations. In future high temperature plasmas, the current diffusive mode determines the stability limit for the global mode. (author)

Resistencia a antibióticos no betalactámicos de aislamientos invasores de Streptococcus pneumoniae en niños latinoamericanos: SIREVA II, 2000-2005 Resistance to non-beta-lactam antibiotics in the clinical isolates of Streptococcus pneumoniae of children in Latin America: SIREVA II, 2000-2005

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Clara Inés Agudelo

2009-04-01

susceptibility was determined through the methods established and standardized by the SIREVA project. Multidrug resistance was defined as: resistance to three or more antibiotics of the same class; to the non-beta-lactams analyzed by this study; or, to the beta-lactams evaluated by a previous study, in which 37.8% of these isolates showed decreased susceptibility to penicillin. RESULTS:Some degree of resistance was found to TMP-SMZ and erythromycin (56.4% and 15.4% of the isolates studied, respectively, with 4.6% highly resistant to chloramphenicol. All isolates were susceptible to vancomycin. The highest prevalence of TMP-SMZ resistance was observed in the pneumonia isolates; and that of erythromycin, in cases of sepsis (61.6% and 25.5%, respectively; P < 0.01. The high-est prevalence of TMP-SMZ resistance was found in Brazil (71.9%, and that of erythromycin, in Mexico (38.2% and Venezuela (32.9%. The 14, 6B, 19F, and 23F serotypes were most often associated with resistance to the antibiotics in the study. CONCLUSIONS: High and increasing rates of isolates resistant to TMP-SMZ and erythromycin were observed, as well as a decreasing percentage of isolates resistant to chloramphenicol. These trends highlight differences among the countries studied.

ALK and TGF-Beta Resistance in Breast Cancer

Science.gov (United States)

2017-10-01

Award Number: W81XWH‐15‐1‐0650 TITLE: ALK and TGF-Beta Resistance in Breast Cancer PRINCIPAL INVESTIGATOR: Xin-Hua Feng CONTRACTING...and TGF-Beta Resistance in Breast Cancer 5b. GRANT NUMBER W81XWH‐15‐1‐0650 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Xin-Hua Feng...response is a hallmark in human cancer . However, the mechanisms underlying TGF- resistance in breast cancer have not been elucidated. Anaplastic

Appearance of β-lactam Resistance Genes in Agricultural Soils and Clinical Isolates over the 20th Century

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Graham, David W.; Knapp, Charles W.; Christensen, Bent T.; McCluskey, Seánín; Dolfing, Jan

2016-02-01

Debate exists about whether agricultural versus medical antibiotic use drives increasing antibiotic resistance (AR) across nature. Both sectors have been inconsistent at antibiotic stewardship, but it is unclear which sector has most influenced acquired AR on broad scales. Using qPCR and soils archived since 1923 at Askov Experimental Station in Denmark, we quantified four broad-spectrum β-lactam AR genes (ARG; blaTEM, blaSHV, blaOXA and blaCTX-M) and class-1 integron genes (int1) in soils from manured (M) versus inorganic fertilised (IF) fields. “Total” β-lactam ARG levels were significantly higher in M versus IF in soils post-1940 (paired-t test; p animal manure and humans are historically interconnected. Archive data further show when non-therapeutic antibiotic use was banned in Denmark, blaCTX-M levels declined in M soils, suggesting accumulated soil ARGs can be reduced by prudent antibiotic stewardship. Conversely, int1 levels have continued to increase in M soils since 1990, implying direct manure application to soils should be scrutinized as part of future stewardship programs.

Extended Spectrum Beta-lactamases: Definition, Classification and Epidemiology.

Science.gov (United States)

Ghafourian, Sobhan; Sadeghifard, Nourkhoda; Soheili, Sara; Sekawi, Zamberi

2015-01-01

Extended spectrum beta-lactamases (ESBLs) are defined as enzymes produced by certain bacteria that are able to hydrolyze extended spectrum cephalosporin. They are therefore effective against beta-lactam antibiotics such as ceftazidime, ceftriaxone, cefotaxime and oxyimino-monobactam. The objective of the current review is to provide a better understanding of ESBL and the epidemiology of ESBL producing organisms which are among those responsible for antibiotic resistant strains. Globally, ESBLs are considered to be problematic, particularly in hospitalized patients. There is an increasing frequency of ESBL in different parts of the world. The high risk patients are those contaminated with ESBL producer strains as it renders treatment to be ineffective in these patients. Thus, there an immediate needs to identify EBSL and formulate strategic policy initiatives to reduce their prevalence.

Exposure of clinical MRSA heterogeneous strains to β-lactams redirects metabolism to optimize energy production through the TCA cycle.

Science.gov (United States)

Keaton, Mignon A; Rosato, Roberto R; Plata, Konrad B; Singh, Christopher R; Rosato, Adriana E

2013-01-01

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as one of the most important pathogens both in health care and community-onset infections. The prerequisite for methicillin resistance is mecA, which encodes a β-lactam-insensitive penicillin binding protein PBP2a. A characteristic of MRSA strains from hospital and community associated infections is their heterogeneous expression of resistance to β-lactam (HeR) in which only a small portion (≤ 0.1%) of the population expresses resistance to oxacillin (OXA) ≥ 10 µg/ml, while in other isolates, most of the population expresses resistance to a high level (homotypic resistance, HoR). The mechanism associated with heterogeneous expression requires both increase expression of mecA and a mutational event that involved the triggering of a β-lactam-mediated SOS response and related lexA and recA genes. In the present study we investigated the cellular physiology of HeR-MRSA strains during the process of β-lactam-mediated HeR/HoR selection at sub-inhibitory concentrations by using a combinatorial approach of microarray analyses and global biochemical profiling employing gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS) to investigate changes in metabolic pathways and the metabolome associated with β-lactam-mediated HeR/HoR selection in clinically relevant heterogeneous MRSA. We found unique features present in the oxacillin-selected SA13011-HoR derivative when compared to the corresponding SA13011-HeR parental strain that included significant increases in tricarboxyl citric acid (TCA) cycle intermediates and a concomitant decrease in fermentative pathways. Inactivation of the TCA cycle enzyme cis-aconitase gene in the SA13011-HeR strain abolished β-lactam-mediated HeR/HoR selection demonstrating the significance of altered TCA cycle activity during the HeR/HoR selection. These results provide evidence of both the metabolic cost and the adaptation that He

Exposure of clinical MRSA heterogeneous strains to β-lactams redirects metabolism to optimize energy production through the TCA cycle.

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Mignon A Keaton

Full Text Available Methicillin-resistant Staphylococcus aureus (MRSA has emerged as one of the most important pathogens both in health care and community-onset infections. The prerequisite for methicillin resistance is mecA, which encodes a β-lactam-insensitive penicillin binding protein PBP2a. A characteristic of MRSA strains from hospital and community associated infections is their heterogeneous expression of resistance to β-lactam (HeR in which only a small portion (≤ 0.1% of the population expresses resistance to oxacillin (OXA ≥ 10 µg/ml, while in other isolates, most of the population expresses resistance to a high level (homotypic resistance, HoR. The mechanism associated with heterogeneous expression requires both increase expression of mecA and a mutational event that involved the triggering of a β-lactam-mediated SOS response and related lexA and recA genes. In the present study we investigated the cellular physiology of HeR-MRSA strains during the process of β-lactam-mediated HeR/HoR selection at sub-inhibitory concentrations by using a combinatorial approach of microarray analyses and global biochemical profiling employing gas chromatography/mass spectrometry (GC/MS and liquid chromatography/mass spectrometry (LC/MS to investigate changes in metabolic pathways and the metabolome associated with β-lactam-mediated HeR/HoR selection in clinically relevant heterogeneous MRSA. We found unique features present in the oxacillin-selected SA13011-HoR derivative when compared to the corresponding SA13011-HeR parental strain that included significant increases in tricarboxyl citric acid (TCA cycle intermediates and a concomitant decrease in fermentative pathways. Inactivation of the TCA cycle enzyme cis-aconitase gene in the SA13011-HeR strain abolished β-lactam-mediated HeR/HoR selection demonstrating the significance of altered TCA cycle activity during the HeR/HoR selection. These results provide evidence of both the metabolic cost and the

Lactam inhibiting Streptococcus mutans growth on titanium

International Nuclear Information System (INIS)

Xavier, J.G.; Geremias, T.C.; Montero, J.F.D.; Vahey, B.R.; Benfatti, C.A.M.; Souza, J.C.M.; Magini, R.S.; Pimenta, A.L.

2016-01-01

The aim of this work was to analyze the activity of novel synthetic lactams on preventing biofilm formation on titanium surfaces. Titanium (Ti6Al4V) samples were exposed to Streptococcus mutans cultures in the presence or absence of a synthetic lactam. After 48 h incubation, planktonic growth was determined by spectrophotometry. Biofilm was evaluated by crystal violet staining and colony forming units (CFU·ml −1 ), followed by scanning electron microscopy (SEM). Results showed that the average of adhered viable cells was approximately 1.5 × 10 2 CFU/ml in the presence of lactam and 4 × 10 2 CFU/ml in its absence. This novel compound was considerable active in reducing biofilm formation over titanium surfaces, indicating its potential for the development of antimicrobial drugs targeting the inhibition of the initial stages of bacterial biofilms on dental implants abutments. - Highlights: • A novel synthetic compound is tested on preventing biofilm formation on titanium surfaces • Biofilm inhibition has been achieved on titanium surfaces containing the novel compound. • Planktonic growth of S. mutans was not affected by the presence of lactams on titanium.

Lactam inhibiting Streptococcus mutans growth on titanium

Energy Technology Data Exchange (ETDEWEB)

Xavier, J.G.; Geremias, T.C.; Montero, J.F.D. [Center for Research on Dental Implants (CEPID), School of Dentistry (ODT), Federal University of Santa Catarina - UFSC, Florianópolis/SC, 88040-900 (Brazil); Vahey, B.R. [Herman Ostrow School of Dentistry of USC, 925 W 34 St, Los Angeles, CA 90089 (United States); Benfatti, C.A.M.; Souza, J.C.M.; Magini, R.S. [Center for Research on Dental Implants (CEPID), School of Dentistry (ODT), Federal University of Santa Catarina - UFSC, Florianópolis/SC, 88040-900 (Brazil); Pimenta, A.L., E-mail: andrea@intelab.ufsc.br [Department of Biologia, ERRMECe, Université de Cergy Pontoise, 2, Av. Adolphe Chauvin 95302 Cergy, Pontoise (France); Integrated Laboratories Technologies (InteLab), Dept. Chemical and Food Engineering (EQA), Federal University of Santa Catarina - UFSC, Florianópolis/SC, 88040-970 (Brazil)

2016-11-01

The aim of this work was to analyze the activity of novel synthetic lactams on preventing biofilm formation on titanium surfaces. Titanium (Ti6Al4V) samples were exposed to Streptococcus mutans cultures in the presence or absence of a synthetic lactam. After 48 h incubation, planktonic growth was determined by spectrophotometry. Biofilm was evaluated by crystal violet staining and colony forming units (CFU·ml{sup −1}), followed by scanning electron microscopy (SEM). Results showed that the average of adhered viable cells was approximately 1.5 × 10{sup 2} CFU/ml in the presence of lactam and 4 × 10{sup 2} CFU/ml in its absence. This novel compound was considerable active in reducing biofilm formation over titanium surfaces, indicating its potential for the development of antimicrobial drugs targeting the inhibition of the initial stages of bacterial biofilms on dental implants abutments. - Highlights: • A novel synthetic compound is tested on preventing biofilm formation on titanium surfaces • Biofilm inhibition has been achieved on titanium surfaces containing the novel compound. • Planktonic growth of S. mutans was not affected by the presence of lactams on titanium.

TEM and CTX-M extended-spectrum beta-lactamase in Klebsiella spp and Escherichia coli isolates from inanimate surfaces of hospital environments

OpenAIRE

Rivera-Jacinto, Marco; Facultad de Ciencias de la Salud, Universidad Nacional de Cajamarca. Cajamarca, Perú.; Rodríguez-Ulloa, Claudia; Facultad de Ciencias de la Salud, Universidad Nacional de Cajamarca. Cajamarca, Perú.; Flores Clavo, René; Hospital Regional de Lambayeque. Lambayeque, Perú.; Serquén López, Luis; Hospital Regional de Lambayeque. Lambayeque, Perú.; Arce Gil, Zhandra; Universidad Católica Santo Toribio de Mogrovejo. Lambayeque, Perú.

2015-01-01

The aim of the study was to determine the genotype of 15 ESBL strains of Enterobacteriaceae resistant to beta-lactams, isolated from inanimate surfaces and phenotypically characterized as producing extended-spectrum beta-lactamase. After evaluation and screening of the bacterial strains, a PCR was conducted to amplify fragments of 1078 bp and 544 bp corresponding to type TEM and CTX-M ESBL. Eleven strains presented both fragments at the time and only three had blaCTX-M. In conclusion, the pre...

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

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Frank Thierry

2011-08-01

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

ISAba1 and Tn6168 acquisition by natural transformation leads to third-generation cephalosporins resistance in Acinetobacter baumannii.

Science.gov (United States)

Domingues, Sara; Rosário, Natasha; Ben Cheikh, Hadhemi; Da Silva, Gabriela Jorge

2018-05-15

Acinetobacter baumannii has intrinsic beta-lactamase genes, namely ampC and bla OXA-51 -like, which are only strongly expressed when the ISAba1 insertion sequence is upstream the 5' end of the genes. A second ampC gene has also been identified in some clinical A. baumannii strains. The increased expression of these genes leads to resistance to beta-lactams, including third-generation cephalosporins and/or carbapenems. The aim of this work was to assess the involvement of natural transformation in the transfer of chromosomal ampC-associated mobile elements, and related changes in the resistance profile of recipient cells. Natural transformation assays with the naturally competent A. baumannii A118 clinical isolate as recipient cell and the multidrug resistant A. baumannii Ab51 clinical isolate as the source of donor DNA produced transformants. All tested transformants showed integration of the ISAba1 close to the ampC gene. In two transformants, the ISAba1 was acquired by transposition and inserted between the usual folE and the ampC genes. The remaining transformants acquired the ISAba1 adjacent to a second ampC gene, as part of Tn6168, likely by homologous recombination. Our study demonstrates that natural transformation can contribute to the widespread of beta-lactams resistance, and acquisition of non-resistant determinants can lead to changes in the susceptibility profile of A. baumannii strains. Copyright © 2018 Elsevier B.V. All rights reserved.

Longitudinal nasopharyngeal carriage and antibiotic resistance of respiratory bacteria in indigenous Australian and Alaska native children with bronchiectasis.

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Kim M Hare

Full Text Available BACKGROUND: Indigenous children in Australia and Alaska have very high rates of chronic suppurative lung disease (CSLD/bronchiectasis. Antibiotics, including frequent or long-term azithromycin in Australia and short-term beta-lactam therapy in both countries, are often prescribed to treat these patients. In the Bronchiectasis Observational Study we examined over several years the nasopharyngeal carriage and antibiotic resistance of respiratory bacteria in these two PCV7-vaccinated populations. METHODS: Indigenous children aged 0.5-8.9 years with CSLD/bronchiectasis from remote Australia (n = 79 and Alaska (n = 41 were enrolled in a prospective cohort study during 2004-8. At scheduled study visits until 2010 antibiotic use in the preceding 2-weeks was recorded and nasopharyngeal swabs collected for culture and antimicrobial susceptibility testing. Analysis of respiratory bacterial carriage and antibiotic resistance was by baseline and final swabs, and total swabs by year. RESULTS: Streptococcus pneumoniae carriage changed little over time. In contrast, carriage of Haemophilus influenzae declined and Staphylococcus aureus increased (from 0% in 2005-6 to 23% in 2010 in Alaskan children; these changes were associated with increasing age. Moraxella catarrhalis carriage declined significantly in Australian, but not Alaskan, children (from 64% in 2004-6 to 11% in 2010. While beta-lactam antibiotic use was similar in the two cohorts, Australian children received more azithromycin. Macrolide resistance was significantly higher in Australian compared to Alaskan children, while H. influenzae beta-lactam resistance was higher in Alaskan children. Azithromycin use coincided significantly with reduced carriage of S. pneumoniae, H. influenzae and M. catarrhalis, but increased carriage of S. aureus and macrolide-resistant strains of S. pneumoniae and S. aureus (proportion of carriers and all swabs, in a 'cumulative dose-response' relationship

Extended-spectrum beta-lactamases in urinary tract infections caused by Enterobacteria: understanding and guidelines for action.

Science.gov (United States)

García-Tello, A; Gimbernat, H; Redondo, C; Arana, D M; Cacho, J; Angulo, J C

2014-12-01

Beta-lactamases are bacterial enzymes that protect microorganisms from the lethal effects of β-lactam antibiotics. The production of beta-lactamases is the most important mechanism of resistance to these antibiotics, especially in Gram-negative bacteria. Review the magnitude of the problem of extended-spectrum beta-lactamases (ESBL) in the urological setting and present the fundamental action guidelines on the issue, the main risk factors and the prevention strategies. A structured search strategy for patient, problem, intervention, comparison and result was conducted in the PubMed-Medline database to identify the most relevant studies related to the management of patients with urinary tract infection by ESBL-producing microorganisms. We also present a caseload analysis of our center on this issue. ESBL are found in Enterobacteria, mainly Klebsiella sp. and Escherichia coli and are characterized by their hydrolytic ability compared with beta-lactam antibiotics, which entails resistance to penicillin, cephalosporin and aztreonam. They are also associated with resistance to other antibiotics. There is a high risk of infection and colonization by ESBL producers in patients with prolonged hospital stays or who required invasive devices. The prior use of antibiotics and stays in residential care are also risk factors. Prevention programs should focus on preventing nosocomial infection. It is essential that a restrictive policy on the use of antibiotics be implemented. The therapy of choice for severe infections is focused on carbapenems, although their indiscriminate use should be avoided. In uncomplicated lower urinary tract infections, fosfomycin and nitrofurantoin are the best treatment alternatives. ESBL-producing strains constitute a true global health problem. Prevention strategies should focus on nosocomial infection. We should not forget, however, that the appearance of these pathogens in community-acquired infections is increasingly frequent. Therapeutic

Antimicrobial resistance of Staphylococcus spp. from small ruminant mastitis in Brazil

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Chirles A. França

2012-08-01

Full Text Available The study aimed to determine the antimicrobial resistance patterns and to identify molecular resistance markers in Staphylococcus spp. (n=210 isolated from small ruminant mastitis in Brazil. The antimicrobial resistance patterns were evaluated by the disk diffusion test and by detection of the presence of mecA, blaZ, ermA, ermB, ermC and msrA genes by PCR. The efflux pump test was performed using ethidium bromide and biofilm production was determined by Congo red agar test along with PCR for detection of the icaD gene. The isolates were most resistant to amoxicillin (50.0%, streptomycin (42.8%, tetracycline (40.4%, lincomycin (39.0% and erythromycin (33.8%. Pan-susceptibility to all tested drugs was observed in 71 (33.8% isolates and 41 Staphylococcus isolates were positive for the efflux pump. Although phenotypic resistance to oxacillin was observed in 12.8% of the isolates, none harbored the mecA gene. However, 45.7% of the isolates harbored blaZ indicating that beta-lactamase production was the main mechanism associated with staphylococci resistance to beta-lactams in the present study. The other determinants of resistance to antimicrobial agents ermA, ermB, ermC, and msrA were observed in 1.4%, 10.4%, 16.2%, and 0.9% of the isolates, respectively. In addition, the icaD gen was detected in 32.9% of the isolates. Seventy three isolates (54 from goats and 19 from sheep were negative for all resistance genes tested and 69 isolates presented two or more resistance genes. Association among blaZ, ermA, ermB, ermC and efflux pump were observed in 17 isolates, 14 of which originated from goats and three from sheep. The data obtained in this study show the resistance of the isolates to beta-lactamics, which may be associated with the use of antimicrobial drugs without veterinary control.

Beta-lactamases of Mycobacterium tuberculosis and Mycobacterium kansasii.

Science.gov (United States)

Segura, C; Salvadó, M

1997-09-01

Re-emergence of infectious diseases caused by mycobacteria as well as the emergence of multiresistant strains of Mycobacterium has promoted the research on the use of beta-lactames in the treatment of such diseases. Mycobacteria produce beta-lactamases: M. tuberculosis produces a wide-spectrum beta-lactamase whose behaviour mimicks those of Gram-negative bacteria. M. kansasii produces also beta-lactamase which can be inhibited by clavulanic acid. An overview on beta-lactamases from both species is reported.

Meta-genomic analysis of toilet waste from long distance flights; a step towards global surveillance of infectious diseases and antimicrobial resistance

DEFF Research Database (Denmark)

Petersen, Thomas Nordahl; Rasmussen, Simon; Hasman, Henrik

2015-01-01

Human populations worldwide are increasingly confronted with infectious diseases and antimicrobial resistance spreading faster and appearing more frequently. Knowledge regarding their occurrence and worldwide transmission is important to control outbreaks and prevent epidemics. Here, we performed...... for bacteria and antimicrobial resistance genes. An average of 106,839 (0.06%) reads were assigned to resistance genes with genes encoding resistance to tetracycline, macrolide and beta-lactam resistance genes as the most abundant in all samples. We found significantly higher abundance and diversity of genes...

Alergia a beta-lactâmicos na clínica pediátrica: uma abordagem prática Allergy to beta-lactams in pediatrics: a practical approach

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Nelson A. Rosário

2006-11-01

Full Text Available OBJETIVO: Apresentar uma abordagem prática ao diagnóstico e conduta na alergia a antibióticos beta-lactâmicos. FONTES DOS DADOS: Periódicos da área de alergia indexados nas bases MEDLINE e LILACS, além de estudos e textos clássicos que tratam do tema. SÍNTESE DOS DADOS: A alergia à penicilina é relatada com freqüência, em muitos casos resultando na exclusão desse medicamento do arsenal terapêutico. Cerca de 10% dos relatos de alergia a drogas são confirmados. As manifestações clínicas decorrentes da reação alérgica à penicilina são bastante amplas, destacando-se os quadros cutâneos. Os quatro mecanismos de hipersensibilidade de Gell & Coombs estão envolvidos nas reações alérgicas. A penicilina é degradada em determinante maior (95% dos produtos e em determinantes menores (5% dos produtos. As reações imediatas, mediadas por IgE, e que determinam quadros de anafilaxia, estão relacionadas aos determinantes menores em 95% dos casos. A hipersensibilidade a esses produtos pode ser avaliada através de testes cutâneos realizados com os determinantes maior e menores, permitindo, assim, evitar o choque anafilático em indivíduos alérgicos. O texto ressalta conhecimentos básicos sobre a alergia à penicilina, propiciando um diagnóstico mais adequado desse evento e a conduta em casos de suspeita de alergia a beta-lactâmicos. CONCLUSÃO: O diagnóstico de alergia à penicilina tem sido feito de forma inadequada, resultando em sua exclusão do arsenal terapêutico. O melhor reconhecimento dessas condições permitirá o uso da penicilina com diminuição dos riscos decorrentes da hipersensibilidade.OBJECTIVE: To present a practical approach to the diagnosis and management of allergy to beta-lactam antibiotics. SOURCES: Allergy journals indexed in MEDLINE and LILACS, as well as seminal studies and texts. SUMMARY OF THE FINDINGS: Allergy to penicillin is commonly reported. In many cases, this results in the decision not

In Vitro and In Vivo Synergy of the Oxadiazole Class of Antibacterials with β-Lactams.

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Janardhanan, Jeshina; Meisel, Jayda E; Ding, Derong; Schroeder, Valerie A; Wolter, William R; Mobashery, Shahriar; Chang, Mayland

2016-09-01

The oxadiazole antibacterials target the bacterial cell wall and are bactericidal. We investigated the synergism of ND-421 with the commonly used β-lactams and non-β-lactam antibiotics by the checkerboard method and by time-kill assays. ND-421 synergizes well with β-lactam antibiotics, and it also exhibits a long postantibiotic effect (4.7 h). We also evaluated the in vivo efficacy of ND-421 in a murine neutropenic thigh infection model alone and in combination with oxacillin. ND-421 has in vivo efficacy by itself in a clinically relevant infection model (1.49 log10 bacterial reduction for ND-321 versus 0.36 log10 for linezolid with NRS119) and acts synergistically with β-lactam antibiotics in vitro and in vivo, and the combination of ND-421 with oxacillin is efficacious in a mouse neutropenic thigh methicillin-resistant Staphylococcus aureus (MRSA) infection model (1.60 log10 bacterial reduction). The activity of oxacillin was potentiated in the presence of ND-421, as the strain would have been resistant to oxacillin otherwise. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

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.

Epidemiology of infections caused by multiresistant gram-negatives: ESBLs, MBLs, panresistant strains.

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Rossolini, Gian Maria; Mantengoli, Elisabetta; Docquier, Jean-Denis; Musmanno, Rosa Anna; Coratza, Grazietta

2007-07-01

Microbial drug resistance is a growing problem of global magnitude. In gram-negative pathogens, the most important resistance problems are encountered in Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter, with increasing trends observed for all major anti-gram-negative agents (beta-lactams, fluoroquinolones and aminoglycosides). A matter of major concern is the emergence of new beta-lactamases capable of degrading the expanded-spectrum cephalosporins and/or carbapenems, such as the extended-spectrum beta-lactamases (ESBLs) and the carbapenemases. These beta-lactamase genes are often associated with resistance determinants to non-beta-lactam agents (e.g. aminoglycosides and fluoroquinolones), and strains producing ESBLs or carbapenemases often exhibit complex multidrug resistant phenotypes and sometimes are panresistant. The problem is worsened by the dearth of new agents active on multidrug-resistant Gram-negatives in the pipeline. The importance to develop better strategies to control resistance is underscored.

The 1.4 Å Crystal Structure of the Class D [beta]-Lactamase OXA-1 Complexed with Doripenem

Energy Technology Data Exchange (ETDEWEB)

Schneider, Kyle D.; Karpen, Mary E.; Bonomo, Robert A.; Leonard, David A.; Powers, Rachel A.; (Grand Valley); (Case Western U.-Med)

2010-01-12

The clinical efficacy of carbapenem antibiotics depends on their resistance to the hydrolytic action of {beta}-lactamase enzymes. The structure of the class D {beta}-lactamase OXA-1 as an acyl complex with the carbapenem doripenem was determined to 1.4 {angstrom} resolution. Unlike most class A and class C carbapenem complexes, the acyl carbonyl oxygen in the OXA-1-doripenem complex is bound in the oxyanion hole. Interestingly, no water molecules were observed in the vicinity of the acyl linkage, providing an explanation for why carbapenems inhibit OXA-1. The side chain amine of K70 remains fully carboxylated in the acyl structure, and the resulting carbamate group forms a hydrogen bond to the alcohol of the 6{alpha}-hydroxyethyl moiety of doripenem. The carboxylate attached to the {beta}-lactam ring of doripenem is stabilized by a salt bridge to K212 and a hydrogen bond with T213, in lieu of the interaction with an arginine side chain found in most other {beta}-lactamase-{beta}-lactam complexes (e.g., R244 in the class A member TEM-1). This novel set of interactions with the carboxylate results in a major shift of the carbapenem's pyrroline ring compared to the structure of the same ring in meropenem bound to OXA-13. Additionally, bond angles of the pyrroline ring suggest that after acylation, doripenem adopts the {Delta}{sup 1} tautomer. These findings provide important insights into the role that carbapenems may have in the inactivation process of class D {beta}-lactamases.

Development of a Transcription Factor-Based Lactam Biosensor

DEFF Research Database (Denmark)

Zhang, Jingwei; Barajas, Jesus F.; Burdu, Mehmet

2017-01-01

Lactams are an important class of commodity chemicals used in the manufacture of nylons, with millions of tons produced every year. Biological production of lactams could be greatly improved by high-throughput sensors for lactam biosynthesis. To identify biosensors of lactams, we applied a chemoi......Lactams are an important class of commodity chemicals used in the manufacture of nylons, with millions of tons produced every year. Biological production of lactams could be greatly improved by high-throughput sensors for lactam biosynthesis. To identify biosensors of lactams, we applied...... a chemoinformatic approach inspired by small molecule drug discovery. We define this approach as analogue generation toward catabolizable chemicals or AGTC. We discovered a lactam biosensor based on the ChnR/Pb transcription factor-promoter pair. The microbial biosensor is capable of sensing ε-caprolactam, Î......´-valerolactam, and butyrolactam in a dose-dependent manner. The biosensor has sufficient specificity to discriminate against lactam biosynthetic intermediates and therefore could potentially be applied for high-throughput metabolic engineering for industrially important high titer lactam biosynthesis....

Better Renal Resistive Index Profile in Subjects with Beta Thalassemia Minor .

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Basut, Fahrettin; Keşkek, Şakir Özgür; Gülek, Bozkurt

2018-05-03

Beta thalassaemia minor is a common genetic disorder without any characteristic symptoms except mild anemia. It is found to be associated with some cardiovascular risk factors such as insulin resistance and diabetes mellitus. The renal resistive index (RRI) is a measure of renal arterial resistance to blood flow. The aim of this study was to evaluate the renal resistive index in subjects with beta thalassaemia minor (BTM). A total of 253 subjects were included in this cross-sectional study. The study group consisted of 148 subjects with BTM and the control group consisted of 105 healthy subjects. Beta thalassaemia minor was diagnosed by complete blood count and hemoglobin electrophoresis. Blood pressure measurement and biochemical tests were performed. Renal resistive index of all subjects was measured using renal Doppler ultrasonography. Subjects with beta thalassemia minor had lower renal resistive indices compared to healthy subjects (0.58 ± 0.04 vs. 0.60 ± 0.06, p = 0.0016). Additionally, the RRI levels of subjects with BTM were correlated with systolic blood pressure (p = 0.017, r = 0.194). In this study, lower renal resistive index was found in subjects with BTM. This may be associated with decreased vascular resistance and blood viscosity in these subjects. ©2018The Author(s). Published by S. Karger AG, Basel.

Trace determination of 10 beta-lactam antibiotics in environmental and food samples by capillary liquid chromatography.

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Bailón-Pérez, M I; García-Campaña, A M; del Olmo-Iruela, M; Gámiz-Gracia, L; Cruces-Blanco, C

2009-11-20

A sensitive and reliable method using capillary HPLC with UV-diode array detection (DAD) has been developed and validated for the trace determination of residues of 10 beta-lactam antibiotics of human and veterinary use, in milk, chicken meat and environmental water samples. The analytes included ampicillin, amoxicillin, penicillin V, penicillin G, cloxacillin, oxacillin, dicloxacillin, nafcillin, piperacillin and clavulanic acid. Legal levels are regulated by the EU Council regulation 2377/90 in animal edible tissues for these compounds. For food analysis, a solid-phase extraction (SPE) procedure consisting in a tandem of Oasis HLB and Alumina N cartridges was applied for off-line preconcentration and cleanup. For water analysis, the first step was only necessary. The limits of detection for the studied compounds were between 0.04-0.06 microg l(-1) for water samples and 0.80-1.40 microg l(-1) (or microg kg(-1)) in the case of foods derived from animals. Average recoveries for fortified samples at different concentration levels ranged between 82.9% and 98.2%, with relative standard deviations (RSDs) lower than 9%. The method showed the advantages of capillary HPLC for the detection of these widely applied antibiotics in different samples at very low concentration levels.

Glycopeptides versus β-lactams for the prevention of surgical site infections in cardiovascular and orthopedic surgery: a meta-analysis.

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Saleh, Anas; Khanna, Ashish; Chagin, Kevin M; Klika, Alison K; Johnston, Douglas; Barsoum, Wael K

2015-01-01

To compare the efficacy of glycopeptides and β-lactams in preventing surgical site infections (SSIs) in cardiac, vascular, and orthopedic surgery. The cost-effectiveness of switching from β-lactams to glycopeptides for preoperative antibiotic prophylaxis has been controversial. β-Lactams are generally recommended in clean surgical procedures, but they are ineffective against resistant gram-positive bacteria. PubMed, International Pharmaceuticals Abstracts, Scopus, and Cochrane were searched for randomized clinical trials comparing glycopeptides and β-lactams for prophylaxis in adults undergoing cardiac, vascular, or orthopedic surgery. Abstracts and conference proceedings were included. Two independent reviewers performed study selection, data extraction, and assessment of risk of bias. Fourteen studies with a total of 8952 patients were analyzed. No difference was detected in overall SSIs between antibiotic types. However, compared with β-lactams, glycopeptides reduced the risk of resistant staphylococcal SSIs by 48% (relative risk, 0.52; 95% confidence interval, 0.29-0.93; P = 0.03) and enterococcal SSIs by 64% (relative risk, 0.36; 95% confidence interval, 0.16-0.80; P = 0.01), but increased respiratory tract infections by 54% (relative risk, 1.54; 95% confidence interval, 1.19-2.01; P ≤ 0.01). Subgroup analysis of cardiac procedures showed superiority of β-lactams in preventing superficial and deep chest SSIs, susceptible staphylococcal SSIs, and respiratory tract infections. Glycopeptides reduce the risk of resistant staphylococcal SSIs and enterococcal SSIs, but increase the risk of respiratory tract infections. Additional high-quality randomized clinical trials are needed as these results are limited by high risk of bias.

Phenotypic Characterization of Multidrug-resistant Escherichia Coli with Special Reference to Extended-spectrum-beta-lactamases and Metallo-beta-lactamases in a Tertiary Care Center.

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Shrestha, B; Shrestha, S; Mishra, S K; Kattel, H P; Tada, T; Ohara, H; Kirikae, T; Rijal, B P; Sherchand, J B; Pokhrel, B M

2015-01-01

The increasing reports on extended-spectrum-beta-lactamase and metallo-beta-lactamase producing Escherichia coli have addressed a potential threat to global health since it is found to be highly resistance to most of the currently available antibiotics including carbapenems. The present study was aimed to determine the antibiogram of extended-spectrum-beta-lactamase and metallo-beta-lactamase producing MDR E. coli isolates from various clinical samples. This was a cross-sectional study conducted over a period of seven months from December 2013 to July 2014 at bacteriology laboratory of Tribhuvan University Teaching Hospital. A total of 250 clinical specimens (urine, pus, sputum, blood, body fluid, bile, tissue and central venous pressure line tip) were processed from inpatients, with multidrug-resistant Escherichia coli infections. Standard microbiological techniques were used for isolation and identification of the isolates. The presence of extended-spectrum-beta-lactamase was detected by phenotypic confirmatory test recommended by Clinical and Laboratory Standards Institute and imipenem (IMP) /EDTA combined disc method was performed to detect metallo-beta-lactamase mediated resistance mechanism. We found high level of beta lactamase mediated resistance mechanism as part of multidrug resistance. Among 250 MDR isolates, 60% isolates were extended-spectrum-beta-lactamase producers and 17.2% isolates were metallo-beta-lactamase producers. Co-existence of extended-spectrum-beta-lactamase and metallo-beta-lactamase identified in 6.8% isolates. Beta-lactamase mediated resistance mechanisms are accounting very high in the multidrug resistant isolates of E. coli. Therefore, early detection of beta lactamase mediated resistant strains and their current antibiotic susceptibility pattern is necessary to avoid treatment failure and prevent the spread of MDR.

Antibiotic resistance of coagulase-negative staphylococci isolated from artisanal Naples-type salami.

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Mauriello, G; Moschetti, G; Villani, F; Blaiotta, G; Coppola, S

2000-01-01

In the present paper 42 isolates from Italian salami were specified as Staphylococcus xylosus (30), Staph. capitis (1), Staph. saprophyticus (1), Staph. hominis (1), Staph. simulans (1), Staph. cohnii (1) and as Staph. spp. (7). These strains were coagulase-negative and were examined for resistance/sensitivity against 25 antibiotics including beta-lactams (7), macrolides (3), amynoglicosides (5), glycopeptides, lincosamides (4) and novobiocin, fusidic acid, chloramphenicol, rifampicin, tetracycline, minocycline. More than 64% of the strains were resistant to lincomycin, penicillin G, amoxicillin, fusidic acid and novobiocin. All the strains were multiresistant and displayed at least three resistances. Over 75% had a multiple antibiotic resistance (MAR) index between 0.2 and 0.5.

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.

Design, synthesis and bioactivity evaluation of tribactam beta lactamase inhibitors.

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Copar, Anton; Prevec, Tadeja; Anzic, Borut; Mesar, Tomaz; Selic, Lovro; Vilar, Mateja; Solmajer, Tom

2002-03-25

Known carbapenem compounds with inhibitory effect towards beta-lactamase enzymes are formed from bicyclical beta lactam structural scaffolds. On the basis of results from theoretical computational methods and molecular modelling we have designed and developed a synthetic route towards novel, biologically active tricyclic derivatives of carbapenems.

Resistance training & beta-hydroxy-beta-methylbutyrate supplementation on hormones

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Hamid Arazi

2015-10-01

Full Text Available RESUMOIntroduction:In recent years, there was an increased interest on the effects of beta-hydroxy-beta-methylbutyrate (HMB supplementation on skeletal muscle due to its anti-catabolic effects.Objectives:To investigate the effect of HMB supplementation on body composition, muscular strength and anabolic-catabolic hormones after resistance training.Methods:Twenty amateur male athletes were randomly assigned to supplement and control groups in a double-blind crossover design and participated in four weeks resistance training. Before and after the test period fasting blood samples were obtained to determine anabolic (the growth hormone and testosterone and catabolic (cortisol hormones, and fat mass, lean body mass (LBM and muscular strength were measured. Dependent and independent t-tests were used to analyze data.Results:After the training period, there were no significant differen-ces between the groups with respect to fat mass, LBM and anabolic-catabolic hormones. HMB supplementation resulted in a significantly greater strength gain (p≤0.05.Conclusion:Greater increase in strength for HMB group was not accompanied by body composition and basal circulating anabolic-catabolic hormonal changes. It seems that HMB supplementation may have beneficial effects on neurological adaptations of strength gain.

Diversity, distribution and quantification of antibiotic resistance genes in goat and lamb slaughterhouse surfaces and meat products.

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Leyre Lavilla Lerma

Full Text Available The distribution and quantification of tetracycline, sulfonamide and beta-lactam resistance genes were assessed in slaughterhouse zones throughout meat chain production and the meat products; this study represents the first to report quantitatively monitor antibiotic resistance genes (ARG in goat and lamb slaughterhouse using a culture independent approach, since most studies focused on individual bacterial species and their specific resistance types. Quantitative PCR (qPCR revealed a high prevalence of tetracycline resistance genes tetA and tetB in almost all slaughterhouse zones. Sulfonamide resistance genes were largely distributed, while beta-lactam resistance genes were less predominant. Statistical analysis revealed that resistant bacteria, in most cases, were spread by the same route in almost all slaughterhouse zones, except for tetB, blaCTX and blaTEM genes, which occurred in few zones as isolated 'hot spots.' The sum of all analyzed ARG indicated that slaughterhouse surfaces and end products act as reservoirs of ARG, mainly tet genes, which were more prevalent in slaughtering room (SR, cutting room (CR and commercial meat products (MP. Resistance gene patterns suggest they were disseminated throughout slaughterhouse zones being also detected in commercial meat products, with significant correlations between different sampling zones/end products and total resistance in SR, CR and white room (WR zones, and also refrigerator 4 (F4 and MP were observed. Strategically controlling key zones in slaughterhouse (SR, CR and WR by adequate disinfection methods could strategically reduce the risks of ARG transmission and minimize the issues of food safety and environment contamination.

Diversity, distribution and quantification of antibiotic resistance genes in goat and lamb slaughterhouse surfaces and meat products.

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Lavilla Lerma, Leyre; Benomar, Nabil; Knapp, Charles W; Correa Galeote, David; Gálvez, Antonio; Abriouel, Hikmate

2014-01-01

The distribution and quantification of tetracycline, sulfonamide and beta-lactam resistance genes were assessed in slaughterhouse zones throughout meat chain production and the meat products; this study represents the first to report quantitatively monitor antibiotic resistance genes (ARG) in goat and lamb slaughterhouse using a culture independent approach, since most studies focused on individual bacterial species and their specific resistance types. Quantitative PCR (qPCR) revealed a high prevalence of tetracycline resistance genes tetA and tetB in almost all slaughterhouse zones. Sulfonamide resistance genes were largely distributed, while beta-lactam resistance genes were less predominant. Statistical analysis revealed that resistant bacteria, in most cases, were spread by the same route in almost all slaughterhouse zones, except for tetB, blaCTX and blaTEM genes, which occurred in few zones as isolated 'hot spots.' The sum of all analyzed ARG indicated that slaughterhouse surfaces and end products act as reservoirs of ARG, mainly tet genes, which were more prevalent in slaughtering room (SR), cutting room (CR) and commercial meat products (MP). Resistance gene patterns suggest they were disseminated throughout slaughterhouse zones being also detected in commercial meat products, with significant correlations between different sampling zones/end products and total resistance in SR, CR and white room (WR) zones, and also refrigerator 4 (F4) and MP were observed. Strategically controlling key zones in slaughterhouse (SR, CR and WR) by adequate disinfection methods could strategically reduce the risks of ARG transmission and minimize the issues of food safety and environment contamination.

Methicillin-resistant Staphylococcus aureus emerged long before the introduction of methicillin into clinical practice.

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Harkins, Catriona P; Pichon, Bruno; Doumith, Michel; Parkhill, Julian; Westh, Henrik; Tomasz, Alexander; de Lencastre, Herminia; Bentley, Stephen D; Kearns, Angela M; Holden, Matthew T G

2017-07-20

The spread of drug-resistant bacterial pathogens poses a major threat to global health. It is widely recognised that the widespread use of antibiotics has generated selective pressures that have driven the emergence of resistant strains. Methicillin-resistant Staphylococcus aureus (MRSA) was first observed in 1960, less than one year after the introduction of this second generation beta-lactam antibiotic into clinical practice. Epidemiological evidence has always suggested that resistance arose around this period, when the mecA gene encoding methicillin resistance carried on an SCCmec element, was horizontally transferred to an intrinsically sensitive strain of S. aureus. Whole genome sequencing a collection of the first MRSA isolates allows us to reconstruct the evolutionary history of the archetypal MRSA. We apply Bayesian phylogenetic reconstruction to infer the time point at which this early MRSA lineage arose and when SCCmec was acquired. MRSA emerged in the mid-1940s, following the acquisition of an ancestral type I SCCmec element, some 14 years before the first therapeutic use of methicillin. Methicillin use was not the original driving factor in the evolution of MRSA as previously thought. Rather it was the widespread use of first generation beta-lactams such as penicillin in the years prior to the introduction of methicillin, which selected for S. aureus strains carrying the mecA determinant. Crucially this highlights how new drugs, introduced to circumvent known resistance mechanisms, can be rendered ineffective by unrecognised adaptations in the bacterial population due to the historic selective landscape created by the widespread use of other antibiotics.

Multivariable Analysis of the Association Between Antimicrobial Use and Antimicrobial Resistance in Escherichia coli Isolated from Apparently Healthy Pigs in Japan.

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Makita, Kohei; Goto, Masaki; Ozawa, Manao; Kawanishi, Michiko; Koike, Ryoji; Asai, Tetsuo; Tamura, Yutaka

2016-01-01

The objective of this study was to investigate the association between antimicrobial agent use and antimicrobial resistance in Escherichia coli isolated from healthy pigs using data from 2004 to 2007 in the Japanese Veterinary Antimicrobial Resistance Monitoring System (JVARM). Fecal E. coli isolates from 250 pigs (one isolate each from a pig per farm) were examined for antimicrobial resistance. Information on the use of antimicrobials within preceding 6 months and types of farms recorded in JVARM was collected and statistically analyzed against the resistance patterns. In the univariate analysis, associations between both therapeutic and feed additive use of antimicrobials, and resistance to dihydrostreptomycin, gentamicin, kanamycin, ampicillin, cefazolin, ceftiofur, oxytetracycline, chloramphenicol, trimethoprim, nalidixic acid, enrofloxacin, colistin, and bicozamycin, and husbandry factors were investigated. In multivariable analysis, generalized estimating equations were used to control geographical intraclass correlation. Confounding for structurally unrelated associations was tested using generalized linear models. The results suggested direct and cross selections in the associations between use of aminoglycosides in reproduction farms and resistance to kanamycin, use of tetracyclines in larger farms and resistance to oxytetracycline, use of beta-lactams and resistance to ampicillin, use of phenicols and resistance to chloramphenicol, and use of fluoroquinolones and resistance to nalidixic acid and enrofloxacin. Coselection was suggested in the use of tetracyclines and chloramphenicol resistance. The associations between use of beta-lactams and dihydrostreptomycin resistance, use of macrolides and ampicillin and oxytetracycline resistance, and use of colistin and kanamycin resistance were significant, but were confounded by the simultaneous use of homologous antimicrobials.

Aplikace cíleně modifikovaných enzymů v biosyntézách beta-laktamových antibiotik

OpenAIRE

Schneiderová, Michaela

2012-01-01

Nowadays beta-lactam antibiotics are widely used as bacteriostatic agents. The chemical synthesis of antibiotics or its derivatives could be replaced with biocatalysis. This work deals with basics of industrial synthesis beta-lactam antibiotics and, mainly, with used enzymes. This work acquainted with methodes used in enzyme modifications and improving, so they could fit the best for the industrial syntheses.

WCK 5107 (Zidebactam) and WCK 5153 Are Novel Inhibitors of PBP2 Showing Potent "β-Lactam Enhancer" Activity against Pseudomonas aeruginosa, Including Multidrug-Resistant Metallo-β-Lactamase-Producing High-Risk Clones.

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Moya, Bartolome; Barcelo, Isabel M; Bhagwat, Sachin; Patel, Mahesh; Bou, German; Papp-Wallace, Krisztina M; Bonomo, Robert A; Oliver, Antonio

2017-06-01

Zidebactam and WCK 5153 are novel β-lactam enhancers that are bicyclo-acyl hydrazides (BCH), derivatives of the diazabicyclooctane (DBO) scaffold, targeted for the treatment of serious infections caused by highly drug-resistant Gram-negative pathogens. In this study, we determined the penicillin-binding protein (PBP) inhibition profiles and the antimicrobial activities of zidebactam and WCK 5153 against Pseudomonas aeruginosa , including multidrug-resistant (MDR) metallo-β-lactamase (MBL)-producing high-risk clones. MIC determinations and time-kill assays were conducted for zidebactam, WCK 5153, and antipseudomonal β-lactams using wild-type PAO1, MexAB-OprM-hyperproducing ( mexR ), porin-deficient ( oprD ), and AmpC-hyperproducing ( dacB ) derivatives of PAO1, and MBL-expressing clinical strains ST175 ( bla VIM-2 ) and ST111 ( bla VIM-1 ). Furthermore, steady-state kinetics was used to assess the inhibitory potential of these compounds against the purified VIM-2 MBL. Zidebactam and WCK 5153 showed specific PBP2 inhibition and did not inhibit VIM-2 (apparent K i [ K i app ] > 100 μM). MICs for zidebactam and WCK 5153 ranged from 2 to 32 μg/ml (amdinocillin MICs > 32 μg/ml). Time-kill assays revealed bactericidal activity of zidebactam and WCK 5153. LIVE-DEAD staining further supported the bactericidal activity of both compounds, showing spheroplast formation. Fixed concentrations (4 or 8 μg/ml) of zidebactam and WCK 5153 restored susceptibility to all of the tested β-lactams for each of the P. aeruginosa mutant strains. Likewise, antipseudomonal β-lactams (CLSI breakpoints), in combination with 4 or 8 μg/ml of zidebactam or WCK 5153, resulted in enhanced killing. Certain combinations determined full bacterial eradication, even with MDR MBL-producing high-risk clones. β-Lactam-WCK enhancer combinations represent a promising β-lactam "enhancer-based" approach to treat MDR P. aeruginosa infections, bypassing the need for MBL inhibition. Copyright © 2017

Paper analytical devices for fast field screening of beta lactam antibiotics and antituberculosis pharmaceuticals.

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Weaver, Abigail A; Reiser, Hannah; Barstis, Toni; Benvenuti, Michael; Ghosh, Debarati; Hunckler, Michael; Joy, Brittney; Koenig, Leah; Raddell, Kellie; Lieberman, Marya

2013-07-02

Reports of low-quality pharmaceuticals have been on the rise in the past decade, with the greatest prevalence of substandard medicines in developing countries, where lapses in manufacturing quality control or breaches in the supply chain allow substandard medicines to reach the marketplace. Here, we describe inexpensive test cards for fast field screening of pharmaceutical dosage forms containing beta lactam antibiotics or combinations of the four first-line antituberculosis (TB) drugs. The devices detect the active pharmaceutical ingredients (APIs) ampicillin, amoxicillin, rifampicin, isoniazid, ethambutol, and pyrazinamide and also screen for substitute pharmaceuticals, such as acetaminophen and chloroquine that may be found in counterfeit pharmaceuticals. The tests can detect binders and fillers such as chalk, talc, and starch not revealed by traditional chromatographic methods. These paper devices contain 12 lanes, separated by hydrophobic barriers, with different reagents deposited in the lanes. The user rubs some of the solid pharmaceutical across the lanes and dips the edge of the paper into water. As water climbs up the lanes by capillary action, it triggers a library of different chemical tests and a timer to indicate when the tests are completed. The reactions in each lane generate colors to form a "color bar code" which can be analyzed visually by comparison with standard outcomes. Although quantification of the APIs is poor compared with conventional analytical methods, the sensitivity and selectivity for the analytes is high enough to pick out suspicious formulations containing no API or a substitute API as well as formulations containing APIs that have been "cut" with inactive ingredients.

Community-acquired methicillin-resistant Staphylococcus aureus: an emerging pathogen in orthopaedics.

Science.gov (United States)

Marcotte, Anthony L; Trzeciak, Marc A

2008-02-01

Staphylococcus aureus (S aureus) remains one of the most common pathogens for skin and soft-tissue infections encountered by the orthopaedic surgeon. Community-acquired methicillin-resistant S aureus (CA-MRSA) has become increasingly prevalent, particularly among athletes, children in day care, homeless persons, intravenous drug users, men who have sex with men, military recruits, certain minorities (ie, Alaskan Natives, Native Americans, Pacific Islanders), and prison inmates. Risk factors include antibiotic use within the preceding year, crowded living conditions, compromised skin integrity, contaminated surfaces, frequent skin-to-skin contact, shared items, and suboptimal cleanliness. When a patient presents with a skin or soft-tissue infection, the clinician should determine whether an abscess or other infection needs to be surgically incised and drained. Cultures should be performed. When the patient is a member of an at-risk group or has any of the risk factors for CA-MRSA, beta-lactam antibiotics (eg, methicillin) are no longer a reasonable choice for treatment. Empiric treatment should consist of non-beta-lactam antibiotics active against CA-MRSA.

Recent advances in biochemical and molecular diagnostics for the rapid detection of antibiotic-resistant Enterobacteriaceae: a focus on ß-lactam resistance.

Science.gov (United States)

Decousser, Jean-Winoc; Poirel, Laurent; Nordmann, Patrice

2017-04-01

The rapid detection of resistance is a challenge for clinical microbiologists who wish to prevent deleterious individual and collective consequences such as (i) delaying efficient antibiotic therapy, which worsens the survival rate of the most severely ill patients, or (ii) delaying the isolation of the carriers of multidrug-resistant bacteria and promoting outbreaks; this last consequence is of special concern, and there are an increasing number of approaches and market-based solutions in response. Areas covered: From simple, cheap biochemical tests to whole-genome sequencing, clinical microbiologists must select the most adequate phenotypic and genotypic tools to promptly detect and confirm β-lactam resistance from cultivated bacteria or from clinical specimens. Here, the authors review the published literature from the last 5 years about the primary technical approaches and commercial laboratory reagents for these purposes, including molecular, biochemical and immune assays. Furthermore, the authors discuss their intrinsic and relative performance, and we challenge their putative clinical impact. Expert commentary: Until the availability of fully automated wet and dry whole genome sequencing solutions, microbiologists should focus on inexpensive biochemical tests for cultured isolates or monomicrobial clinical specimen and on using the expensive molecular PCR-based strategies for the targeted screening of complex biological environments.

Frequency of resistance to penicillin and erythromycin of pneumococcal strains that caused ottis media

OpenAIRE

Jovanović Luka; Isailović Katarina; Opavski Nataša

2017-01-01

Introduction: Streptococcus pneumoniae is an important human pathogen and the most common cause of acute otitis media (AOM), especially in children. It is also a common cause of community acquired pneumonia, sepsis and bacterial meningitis. Drug of choice in the treatment of these disease are beta lactam antibiotics, and the first alternative are macrolides. The increasing prevalence of resistance to penicillin and macrolides, among pneumococci, has considerably complicated the treatment. Aim...

Molecular epidemiology and antimicrobial resistance of methicillin-resistant Staphylococcus aureus bloodstream isolates in Taiwan, 2010.

Directory of Open Access Journals (Sweden)

Chih-Jung Chen

Full Text Available The information of molecular characteristics and antimicrobial susceptibility pattern of methicillin-resistant Staphylococcus aureus (MRSA is essential for control and treatment of diseases caused by this medically important pathogen. A total of 577 clinical MRSA bloodstream isolates from six major hospitals in Taiwan were determined for molecular types, carriage of Panton-Valentine leukocidin (PVL and sasX genes and susceptibilities to 9 non-beta-lactam antimicrobial agents. A total of 17 genotypes were identified in 577 strains by pulsotyping. Five major pulsotypes, which included type A (26.2%, belonging to sequence type (ST 239, carrying type III staphylococcal chromosomal cassette mec (SCCmec, type F (18.9%, ST5-SCCmecII, type C (18.5%, ST59-SCCmecIV, type B (12.0%, ST239-SCCmecIII and type D (10.9%, ST59-SCCmecVT/IV, prevailed in each of the six sampled hospitals. PVL and sasX genes were respectively carried by ST59-type D strains and ST239 strains with high frequencies (93.7% and 99.1%, respectively but rarely detected in strains of other genotypes. Isolates of different genotypes and from different hospitals exhibited distinct antibiograms. Multi-resistance to ≥3 non-beta-lactams was more common in ST239 isolates (100% than in ST5 isolates (97.2%, P = 0.0347 and ST59 isolates (8.2%, P<0.0001. Multivariate analysis further indicated that the genotype, but not the hospital, was an independent factor associated with muti-resistance of the MRSA strains. In conclusion, five common MRSA clones with distinct antibiograms prevailed in the major hospitals in Taiwan in 2010. The antimicrobial susceptibility pattern of invasive MRSA was mainly determined by the clonal distribution.

Glutamate dehydrogenase affects resistance to cell wall antibiotics in Bacillus subtilis.

Science.gov (United States)

Lee, Yong Heon; Kingston, Anthony W; Helmann, John D

2012-03-01

The glutamate dehydrogenase RocG of Bacillus subtilis is a bifunctional protein with both enzymatic and regulatory functions. Here we show that the rocG null mutant is sensitive to β-lactams, including cefuroxime (CEF), and to fosfomycin but that resistant mutants arise due to gain-of-function mutations in gudB, which encodes an otherwise inactive glutamate dehydrogenase. In the presence of CEF, ΔrocG ΔgudB mutant cells exhibit growth arrest when they reach mid-exponential phase. Using microarray-based transcriptional profiling, we found that the σ(W) regulon was downregulated in the ΔrocG ΔgudB null mutant. A survey of σ(W)-controlled genes for effects on CEF resistance identified both the NfeD protein YuaF and the flotillin homologue YuaG (FloT). Notably, overexpression of yuaFG in the rocG null mutant prevents the growth arrest induced by CEF. The YuaG flotillin has been shown previously to localize to defined lipid microdomains, and we show here that the yuaFGI operon contributes to a σ(W)-dependent decrease in membrane fluidity. We conclude that glutamate dehydrogenase activity affects the expression of the σ(W) regulon, by pathways that are yet unclear, and thereby influences resistance to CEF and other antibiotics.

Industrial enzymatic production of cephalosporin-based beta-lactams.

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Barber, Michael S; Giesecke, Ulrich; Reichert, Arno; Minas, Wolfgang

2004-01-01

Cephalosporins are chemically closely related to penicillins both work by inhibiting the cell wall synthesis of bacteria. The first generation cephalosporins entered the market in 1964. Second and third generation cephalosporins were subsequently developed that were more powerful than the original products. Fourth generation cephalosporins are now reaching the market. Each newer generation of cephalosporins has greater Gram-negative antimicrobial properties than the preceding generation. Conversely, the 'older' generations of cephalosporins have greater Gram-positive (Staphylococcus and Streptococcus) coverage than the 'newer' generations. Frequency of dosing decreases and palatability generally improve with increasing generations. The advent of fourth generation cephalosporins with the launch of cefepime extended the spectrum against Gram-positive organisms without a significant loss of activity towards Gram-negative bacteria. Its greater stability to beta-lactamases increases its efficacy against drug-resistant bacteria. In this review we present the current situation of this mature market. In addition, we present the current state of the technologies employed for the production of cephalosporins, focusing on the new and environmentally safer 'green' routes to the products. Starting with the fermentation and purification of CPC, enzymatic conversion in conjunction with aqueous chemistry will lead to some key intermediates such as 7-ACA, TDA and TTA, which then can be converted into the active pharmaceutical ingredient (API), again applying biocatalytic technologies and aqueous chemistry. Examples for the costing of selected products are provided as well.

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.

In Vitro Activity of the Histatin Derivative P-113 against Multidrug-Resistant Pathogens Responsible for Pneumonia in Immunocompromised Patients

OpenAIRE

Giacometti, Andrea; Cirioni, Oscar; Kamysz, Wojciech; D'Amato, Giuseppina; Silvestri, Carmela; Prete, Maria Simona Del; Licci, Alberto; Riva, Alessandra; Łukasiak, Jerzy; Scalise, Giorgio

2005-01-01

The in vitro activity of the histatin derivative P-113, alone or combined with eight antibiotics, was investigated against multidrug-resistant strains isolated from clinical specimens of immunocompromised patients with pneumonia. The gram-negative isolates were susceptible to P-113. S. aureus showed less susceptibility. Synergy was demonstrated when P-113 was combined with beta-lactams against gram-negative organisms.

Short communication: β-Lactam resistance and vancomycin heteroresistance in Staphylococcus spp. isolated from bovine subclinical mastitis.

Science.gov (United States)

Mello, Priscila Luiza; Pinheiro, Luiza; Martins, Lisiane de Almeida; Brito, Maria Aparecida Vasconcelos Paiva; Ribeiro de Souza da Cunha, Maria de Lourdes

2017-08-01

The use of antimicrobial agents has led to the emergence of resistant bacterial strains over a relatively short period. Furthermore, Staphylococcus spp. can produce β-lactamase, which explains the survival of these strains in a focus of infection despite the use of a β-lactam antibiotic. The aim of this study was to evaluate the resistance of Staphylococcus spp. isolated from bovine subclinical mastitis to oxacillin and vancomycin (by minimum inhibitory concentration) and to detect vancomycin heteroresistance by a screening method. We also evaluated β-lactamase production and resistance due to hyperproduction of this enzyme and investigated the mecA and mecC genes and performed staphylococcal cassette chromosome mec typing. For this purpose, 181 Staphylococcus spp. isolated from mastitis subclinical bovine were analyzed. Using the phenotypic method, 33 (18.2%) of Staphylococcus spp. were resistant to oxacillin. In contrast, all isolates were susceptible to vancomycin, and heteroresistance was detected by the screening method in 13 isolates. Production of β-lactamase was observed in 174 (96%) of the Staphylococcus spp. isolates. The mecA gene was detected in 8 isolates, all of them belonging to the species Staphylococcus epidermidis, and staphylococcal cassette chromosome mec typing revealed the presence of type I and type IV isolates. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Prevalence and antimicrobial susceptibility patterns of extended spectrum beta-lactamase producing Entrobacteriaceae in the University of Gondar Referral Hospital environments, northwest Ethiopia.

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Engda, Tigist; Moges, Feleke; Gelaw, Aschalew; Eshete, Setegn; Mekonnen, Feleke

2018-05-22

This study aimed at assessing the magnitude, distribution, and the antimicrobial susceptibility of the extended spectrum beta-lactamase producing Entrobacteriaceae in the University of Gondar Referral Hospital environments. Out of a total of 384 samples, 14.8% were ESBL producing Entrobacteriaceae, where 42.10% Klebsiella pneumoniae, 35.09% Escherchia coli and 7.01% Proteus mirabilis were the predominant isolates. Most ESBL producing isolates, that is, 24.56, 22.8, and 22.8% were found from waste water, sinks and bedside tables respectively. All ESBL producing Entrobacteriaceae were found to be resistant to ceftriaxone, ceftazidime, cefpirome, cefpodoxime, and amoxicillin with Clavulanic acid. Resistance rate was also high for non-beta-lactam antimicrobials, like chloramphenicol (70.18%), cotrimoxazole (64.91%), norfloxacin (42.10%), ciprofloxacin (43.86%), and gentamicin (19.30%).

Investigation of β-lactam antibacterial drugs, β-lactamases, and penicillin-binding proteins with fluorescence polarization and anisotropy: a review

Science.gov (United States)

Shapiro, Adam B.

2016-06-01

This review covers the uses of fluorescence polarization and anisotropy for the investigation of bacterial penicillin binding proteins (PBPs), which are the targets of β-lactam antibacterial drugs (penicillins, cephalosporins, carbapenems, and monobactams), and of the β-lactamase enzymes that destroy these drugs and help to render bacterial pathogens resistant to them. Fluorescence polarization and anisotropy-based methods for quantitation of β-lactam drugs are also reviewed. A particular emphasis is on methods for quantitative measurement of the interactions of β-lactams and other inhibitors with PBPs and β-lactamases.

Altered membrane permeability in multidrug resistant Escherichia ...

African Journals Online (AJOL)

PRECIOUS

2009-11-02

Nov 2, 2009 ... involvement during the transport of β - lactams in multidrug resistant Escherichia coli isolated from extra-intestinal infections. Also, the ... lactam resistance in multidrug resistant E. coli in ESBL and non-ESBL isolates. .... and decreased susceptibility to carbapenems, particularly ertapenem (Perez et al.,.

Analysis of antibiotic resistance pattern of S. aureus strains isolated from the Orthopedics-Traumatology Section of "Sf. Spiridon" Clinical Emergency Hospital, Iaşi.

Science.gov (United States)

Tucaliuc, D; Alexa, O; Tuchiluş, Cristina Gabriela; Ursu, Ramona Gabriela; Tucaliuc, Elena Simona; Iancu, Luminiţa Smaranda

2014-01-01

The retrospective analysis of antibiotic sensibility of S. aureus strains isolated from infected patients from the Orthopedics-Traumatology Clinic of "Sf. Spiridon" Clinical Emergency Hospital, Iaşi during January 2003-December 2013, in view of determining the evolution trend of the resistance phenomenon and of pinpointing the most useful treatment for these strains. The antibiotic sensitivity test was carried out using two methods: diffusimetric-Kirby-Bauer and the MIC determination by E-test (for the strains isolated in 2013); the interpretation of the sensitivity was made in a standardized manner, in compliance with the CLSI (Clinical and Laboratory Standards Institute) standard for antibiotics testing in force. The sensitivity testing for beta-lactams proved that during the 11 years of the study, the average value of the frequency of resistant strains was of 41.59% +/- 8.68. The highest frequency of MRSA (Methicillin Restant S. aureus) strains was noticed in 2012 (58.6%), followed by 2004 (50.7%). Even if in 2013 it dropped to 38.9%, the trend calculated for 2003-2013 is slightly rising (y = 0.0073x + 0.372). Out of the total of 495 S. aureus strains that were isolated, 164 (33.13%) were completely sensitive to the tested antibiotics and 26 (5.25%) were resistant only to beta-lactams. The other MRSA strains associated multiple resistance and MIC for vancomycin varied between 0.5-2 mg/ml. Two strains whose MIC was of 0.5 mg/ml were sensitive to most classes of tested antibiotics, including beta-lactams, except for macrolides (erythromycin), and the strain whose MIC was of 2 mg/ml, was resistant to all classes of tested antibiotics, except for glycopeptides and oxazolidiones. The other tested strains had a MIC for vancomycin equal to 1 mg/ml. Due to the fact that there are infections with SAMR strains in a rather worrying percentage (53.9%) that are resistant to the other classes of antibiotics, the only therapeutic solution being the vancomycin treatment, its

Characterization of multi-drug resistant ESBL producing nonfermenter bacteria isolated from patients blood samples using phenotypic methods in Shiraz (Iran

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Maneli Amin Shahidi

2015-10-01

Full Text Available Background and Aim: The emergence of  nonfermenter bacteria that are resistant to multidrug resistant ESBL  are  nowadays a principal problem  for hospitalized patients. The present study aimed at surveying the emergence of nonfermenter bacteria resistant to multi-drug ESBL producing isolated from patients blood samples using BACTEC 9240 automatic system in Shiraz. Materials and Methods: In this cross-sectional study, 4825 blood specimens were collected from hospitalized patients in Shiraz (Iran, and positive samples were detected by means of  BACTEC 9240 automatic system. The isolates  containing nonfermenter bacteria were identified based on biochemical tests embedded in the API-20E system. Antibiotic sensitivity  test was performed  and identification of  ESBL producing strains were done  using phenotypic detection of extended spectrum beta-lactamase producing isolates(DDST according to CLSI(2013 guidelines.   Results: Out of 4825 blood samples, 1145 (24% specimen were gram-positive using BACTEC system. Among all isolated microorganisms, 206 isolates were non-fermenting gram- negative bacteria. The most common non-fermenter isolates were Pseudomonas spp. (48%, Acinetobacter spp. (41.7% ,and Stenotrophomonas spp. (8.2%. Seventy of them (81.4% were  Acinetobacter spp. which were ESBL positive. Among &beta-lactam antibiotics, Pseudomonas spp. showed  the best sensitivity to piperacillin-tazobactam (46.5%.  Conclusion: It was found that  &beta-lactam antibiotics are not effective against more than 40% of Pseudomonas spp. infections and 78% Acinetobacter infections. Emergence of multi-drug resistant strains that are resistant to most antibiotic classes is a major public health problem in Iran. To resolve this problem using of practical guidelines is critical.

Quantitative analysis of the IgG and IgG subclass immune responses to chromosomal Pseudomonas aeruginosa beta-lactamase in serum from patients with cystic fibrosis by western blotting and laser scanning densitometry

DEFF Research Database (Denmark)

Petersen, T D; Ciofu, O; Pressler, T

1996-01-01

BACKGROUND: Antibodies against chromosomal beta-lactamase of Pseudomonas aeruginosa (a beta ab) are markers of the development of resistance of P aeruginosa to beta-lactam antibiotics in patients with cystic fibrosis and chronic lung infection. The role of these antibodies in patients with chronic...... of the chronic infection the a beta ab titres were higher in patients with good lung function than in those with poor lung function. CONCLUSIONS: The association of a weak IgG3 and a strong IgG4 a beta ab response suggests that the contribution of a beta ab antibodies to lung diseases mediated by immune...... complexes might be less important than other antipseudomonal antibodies. A beneficial neutralising effect of the a beta ab antibodies on the antibiotic destroying enzymes may be an additional factor....

Determination of Beta-Lactam residues in milk by high performance liquid chromatography

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Roseane Brandão de Brito

2006-01-01

Full Text Available A high performance liquid chromatographic method to assay beta-lactam residues in milk was developed and validated. Milk samples were spiked with standard solutions and deproteinated. The extract was cleaned-up on C18 SPE cartridge, the antibiotics eluted with acetonitrile:water (50:50 v/v and derivatized with acetic anhydride and 1-methyl-imidazole solution containing HgCl2. The chromatographic analysis was performed on C18 column using mobile phase consisting of acetonitrile and phosphate buffer (pH 6.5 in the presence of Na2S2O3 gradient and detection at 325 nm. The method was selective for ampicillin, penicillin G and penicillin V, the latter used as internal standard. Average recoveries for ampicillin and penicillin G ranged, respectively, from 60.0% to 104.9% and from 82.7% to 109.2%, with coefficients of variation from 11.1% to 24.6%, and from 2.1% to 25.2%, indicating accuracy and precision. Detection limit of 4.0 µg/L for ampicillin and 3.0 µg/L for penicillin G, and quantification limits of 4.0 µg/L for both were estimated.Um método para determinar resíduos de antibióticos beta-lactâmicos em leite por cromatografia líquida de alta eficiência (CLAE foi desenvolvido e validado. Amostras brancas foram adicionadas de padrão e desproteinizadas. O extrato foi purificado por extração em fase sólida C18, os antibióticos eluídos com acetonitrila:água (50:50 v/v e posteriormente derivatizados com anidrido acético e solução de 1-metil-imidazol contendo HgCl2. A análise cromatográfica foi realizada utilizando coluna C18, fase móvel composta por acetonitrila e tampão fosfato pH 6,5, na presença de Na2S2O3 em gradiente e detecção a 325 nm. O método foi seletivo para ampicilina, penicilina G e penicilina V, sendo este último utilizado como padrão interno. As médias de recuperação para ampicilina e penicilina G situaram-se, respectivamente, na faixa de 60,0% a 104,9% e de 82,7% a 109,2%, com coeficientes de varia

Ceftriaxone, a beta-lactam antibiotic, reduces ethanol consumption in alcohol-preferring rats.

Science.gov (United States)

Sari, Youssef; Sakai, Makiko; Weedman, Jason M; Rebec, George V; Bell, Richard L

2011-01-01

Changes in glutamatergic transmission affect many aspects of neuroplasticity associated with ethanol and drug addiction. For instance, ethanol- and drug-seeking behavior is promoted by increased glutamate transmission in key regions of the motive circuit. We hypothesized that because glutamate transporter 1 (GLT1) is responsible for the removal of most extracellular glutamate, up-regulation or activation of GLT1 would attenuate ethanol consumption. Alcohol-preferring (P) rats were given 24 h/day concurrent access to 15 and 30% ethanol, water and food for 7 weeks. During Week 6, P rats received either 25, 50, 100 or 200 mg/kg ceftriaxone (CEF, i.p.), a β-lactam antibiotic known to elevate GLT1 expression, or a saline vehicle for five consecutive days. Water intake, ethanol consumption and body weight were measured daily for 15 days starting on Day 1 of injections. We also tested the effects of CEF (100 and 200 mg/kg, i.p.) on daily sucrose (10%) consumption as a control for motivated behavioral drinking. Statistical analyses revealed a significant reduction in daily ethanol, but not sucrose, consumption following CEF treatment. During the post treatment period, there was a recovery of ethanol intake across days. Dose-dependent increases in water intake were manifest concurrent with the CEF-induced decreases in ethanol intake. Nevertheless, CEF did not affect body weight. An examination of a subset of the CEF-treated ethanol-drinking rats, on the third day post CEF treatment, revealed increases in GTL1 expression levels within the prefrontal cortex and nucleus accumbens. These results indicate that CEF effectively reduces ethanol intake, possibly through activation of GLT1, and may be a potential therapeutic drug for alcohol addiction treatment.

Anaerobic bacteria and antibiotics: What kind of unexpected resistance could I find in my laboratory tomorrow?

Science.gov (United States)

Dubreuil, L; Odou, M F

2010-12-01

The purpose of this article is to set out some important considerations on the main emerging antibiotic resistance patterns among anaerobic bacteria. The first point concerns the Bacteroides fragilis group and its resistance to the combination of β-lactam+β-lactamase inhibitor. When there is overproduction of cephalosporinase, it results in increased resistance to the β-lactams while maintaining susceptibility to β-lactams/β-lactamase inhibitor combinations. However, if another resistance mechanism is added, such as a loss of porin, resistances to β-lactam+β-lactamase inhibitor combinations may occur. The second point is resistance to metronidazole occurring due to nim genes. PCR detection of nim genes alone is not sufficient for predicting resistance to metronidazole; actual MIC determinations are required. Therefore, it can be assumed that other resistance mechanisms can also be involved. Although metronidazole resistance remains rare for the B. fragilis group, it has nevertheless been detected worldwide and also been observed spreading to other species. In some cases where there is only a decreased susceptibility, clinical failures may occur. The last point concerns resistance of Clostridium species to glycopeptides and lipopeptides. Low levels of resistance have been detected with these antibiotics. Van genes have been detected not only in clostridia but also in other species. In conclusion, antibiotic resistance involves different mechanisms and affects many anaerobic species and is spreading worldwide. This demonstrates the need to continue with antibiotic resistance testing and surveys in anaerobic bacteria. Copyright © 2010 Elsevier Ltd. All rights reserved.

Insight into the effect of inhibitor resistant S130G mutant on physico-chemical properties of SHV type beta-lactamase: a molecular dynamics study.

Directory of Open Access Journals (Sweden)

Mohd Hassan Baig

Full Text Available Bacterial resistance is a serious threat to human health. The production of β-lactamase, which inactivates β-lactams is most common cause of resistance to the β-lactam antibiotics. The Class A enzymes are most frequently encountered among the four β-lactamases in the clinic isolates. Mutations in class A β-lactamases play a crucial role in substrate and inhibitor specificity. SHV and TEM type are known to be most common class A β-lactamases. In the present study, we have analyzed the effect of inhibitor resistant S130G point mutation of SHV type Class-A β-lactamase using molecular dynamics and other in silico approaches. Our study involved the use of different in silico methods to investigate the affect of S130G point mutation on the major physico-chemical properties of SHV type class A β-lactamase. We have used molecular dynamics approach to compare the dynamic behaviour of native and S130G mutant form of SHV β-lactamase by analyzing different properties like root mean square deviation (RMSD, H-bond, Radius of gyration (Rg and RMS fluctuation of mutation. The results clearly suggest notable loss in the stability of S130G mutant that may further lead to decrease in substrate specificity of SHV. Molecular docking further indicates that S130G mutation decreases the binding affinity of all the three inhibitors in clinical practice.

High beta-Lactamase Levels Change the Pharmacodynamics of beta-Lactam Antibiotics in Pseudomonas aeruginosa Biofilms

DEFF Research Database (Denmark)

Wang, Hengzhuang; Ciofu, Oana; Yang, Liang

2013-01-01

the role of beta-lactamase in the pharmacokinetics (PK) and pharmacodynamics (PD) of ceftazidime and imipenem on P. aeruginosa biofilms. P. aeruginosa PAO1 and its corresponding beta-lactamase-overproducing mutant, PA Delta DDh2Dh3, were used in this study. Biofilms of these two strains in flow chambers......, microtiter plates, and on alginate beads were treated with different concentrations of ceftazidime and imipenem. The kinetics of antibiotics on the biofilms was investigated in vitro by time-kill methods. Time-dependent killing of ceftazidime was observed in PAO1 biofilms, but concentration-dependent killing...... activity of ceftazidime was observed for beta-lactamase-overproducing biofilms of P. aeruginosa in all three models. Ceftazidime showed time-dependent killing on planktonic PAO1 and PA Delta DDh2Dh3. This difference is probably due to the special distribution and accumulation in the biofilm matrix of beta...

Clinical and Microbiological Aspects of β-Lactam Resistance in Staphylococcus lugdunensis.

Science.gov (United States)

McHardy, Ian H; Veltman, Jennifer; Hindler, Janet; Bruxvoort, Katia; Carvalho, Marissa M; Humphries, Romney M

2017-02-01

Antimicrobial susceptibility results from broth microdilution MIC testing of 993 Staphylococcus lugdunensis isolates recovered from patients at a tertiary care medical center from 2008 to 2015 were reviewed. Ninety-two oxacillin-susceptible isolates were selected to assess the accuracy of penicillin MIC testing, the penicillin disk diffusion test, and three β-lactamase tests, including the cefoxitin-induced nitrocefin test, penicillin cloverleaf assay, and penicillin disk zone edge test. The results of all phenotypic tests were compared to the results of blaZ PCR. The medical records of 62 patients from whom S. lugdunensis was isolated, including 31 penicillin-susceptible and 31 penicillin-resistant strains, were retrospectively reviewed to evaluate the clinical significance of S. lugdunensis isolation, the antimicrobial agents prescribed, if any, and the clinical outcome. MIC testing revealed that 517/993 (52.1%) isolates were susceptible to penicillin and 946/993 (95.3%) were susceptible to oxacillin. The induced nitrocefin test was 100% sensitive and specific for the detection of β-lactamase compared to the blaZ PCR results, whereas the penicillin disk zone edge and cloverleaf tests showed sensitivities of 100% but specificities of only 9.1% and 89.1%, respectively. The penicillin MIC test had 100% categorical agreement with blaZ PCR, while penicillin disk diffusion yielded one major error. Only 3/31 patients with penicillin-susceptible isolates were treated with a penicillin family antimicrobial. The majority of cases were treated with other β-lactams, trimethoprim-sulfamethoxazole, or vancomycin. These data indicate that nearly all isolates of S. lugdunensis are susceptible to narrow-spectrum antimicrobial agents. Clinical laboratories in areas with resistance levels similar to those described here can help promote the use of these agents versus vancomycin by effectively designing their antimicrobial susceptibility reports to convey this message. Copyright

A Rapid Phenotypic Whole Cell Screening Approach for the Identification of Small Molecule Inhibitors that Counter Beta-lactamase Resistance in Pseudomonas aeruginosa

Science.gov (United States)

Collia, Deanna; Bannister, Thomas D.; Tan, Hao; Jin, Shouguang; Langaee, Taimour; Shumate, Justin; Scampavia, Louis; Spicer, Timothy P.

2017-01-01

Pseudomonas aeruginosa is an opportunistic human pathogen which is prevalent in hospitals and continues to develop resistance to multiple classes of antibiotics. Historically, β-lactam antibiotics have been the first line of therapeutic defense. However, the emergence of multidrug-resistant (MDR) strains of P. aeruginosa, such as AmpC β-lactamase overproducing mutants, limits the effectiveness of current antibiotics. Among AmpC hyper producing clinical isolates, inactivation of AmpG, which is essential for the expression of AmpC, increases bacterial sensitivity to β-lactam antibiotics. We hypothesize that inhibition of AmpG activity will enhance the efficacy of β-lactams against P. aeruginosa. Here, using a highly drug resistant AmpC inducible laboratory strain PAO1, we describe an ultra-high throughput whole cell turbidity assay designed to identify small molecule inhibitors of the AmpG. We screened 645K compounds to identify compounds with the ability to inhibit bacterial growth in the presence of Cefoxitin; an AmpC inducer, and identified 2,663 inhibitors which were also tested in the absence of Cefoxitin to determine AmpG specificity. The Z′ and S:B were robust at 0.87 ± 0.05 and 2.2 ± 0.2, respectively. Through a series of secondary and tertiary studies, including a novel luciferase based counterscreen, we ultimately identified 8 potential AmpG specific inhibitors. PMID:28850797

Residence of Streptococcus pneumoniae and Moraxella catarrhalis within polymicrobial biofilm promotes antibiotic resistance and bacterial persistence in vivo.

Science.gov (United States)

Perez, Antonia C; Pang, Bing; King, Lauren B; Tan, Li; Murrah, Kyle A; Reimche, Jennifer L; Wren, John T; Richardson, Stephen H; Ghandi, Uma; Swords, W Edward

2014-04-01

Otitis media (OM) is an extremely common pediatric ailment caused by opportunists that reside within the nasopharynx. Inflammation within the upper airway can promote ascension of these opportunists into the middle ear chamber. OM can be chronic/recurrent in nature, and a wealth of data indicates that in these cases, the bacteria persist within biofilms. Epidemiological data demonstrate that most cases of OM are polymicrobial, which may have significant impact on antibiotic resistance. In this study, we used in vitro biofilm assays and rodent infection models to examine the impact of polymicrobial infection with Moraxella catarrhalis and Streptococcus pneumoniae (pneumococcus) on biofilm resistance to antibiotic treatment and persistence in vivo. Consistent with prior work, M. catarrhalis conferred beta-lactamase-dependent passive protection from beta-lactam killing to pneumococci within polymicrobial biofilms. Moreover, pneumococci increased resistance of M. catarrhalis to macrolide killing in polymicrobial biofilms. However, pneumococci increased colonization in vivo by M. catarrhalis in a quorum signal-dependent manner. We also found that co-infection with M. catarrhalis affects middle ear ascension of pneumococci in both mice and chinchillas. Therefore, we conclude that residence of M. catarrhalis and pneumococci within the same biofilm community significantly impacts resistance to antibiotic treatment and bacterial persistence in vivo. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Direct Lactamization of Azido Amides via Staudinger-Type Reductive Cyclization

Energy Technology Data Exchange (ETDEWEB)

Heo, In Jung; Lee, Su Jeong; Cho, Chang Woo [Kyungpook National University, Daegu (Korea, Republic of)

2012-01-15

The direct lactamization of 1,3- and 1,4-azido amides has been achieved using triphenylphosphine and water, affording various γ- and δ-lactams in good to excellent yields. The direct lactamization of the azido amides was performed via the Staudinger-type reductive cyclization in which the amide group acts as the electrophile for lactam synthesis. This lactamization provides a mild, functional group tolerant and efficient route for the synthesis of various γ- and δ-lactams found in natural products and pharmaceuticals. Further studies will be conducted to develop new synthetic routes for the synthesis of various lactams. The lactam ring system is one of the most ubiquitous structural motifs found in natural products and pharmaceuticals. Owing to the prevalence of lactams, their synthesis has attracted considerable attention. Lactams are usually prepared by the coupling of activated carboxylic acid derivatives with amines. Alternative routes include the Beckmann rearrangement of oximes, the Schmidt reaction of cyclic ketones and hydrazoic acid, the Kinugasa reaction of nitrones and terminal acetylenes, the Diels-Alder reaction of cyclopentadiene and chlorosulfonyl isocyanate, transition metal catalyzed lactamization of amino alcohols, and iodolactamization of amides and alkenes. In particular, the intramolecular Staudinger ligation of azides and activated carboxy acids, including esters, is well known as an environmentally friendly and mild protocol for lactam synthesis.

Direct Lactamization of Azido Amides via Staudinger-Type Reductive Cyclization

International Nuclear Information System (INIS)

Heo, In Jung; Lee, Su Jeong; Cho, Chang Woo

2012-01-01

The direct lactamization of 1,3- and 1,4-azido amides has been achieved using triphenylphosphine and water, affording various γ- and δ-lactams in good to excellent yields. The direct lactamization of the azido amides was performed via the Staudinger-type reductive cyclization in which the amide group acts as the electrophile for lactam synthesis. This lactamization provides a mild, functional group tolerant and efficient route for the synthesis of various γ- and δ-lactams found in natural products and pharmaceuticals. Further studies will be conducted to develop new synthetic routes for the synthesis of various lactams. The lactam ring system is one of the most ubiquitous structural motifs found in natural products and pharmaceuticals. Owing to the prevalence of lactams, their synthesis has attracted considerable attention. Lactams are usually prepared by the coupling of activated carboxylic acid derivatives with amines. Alternative routes include the Beckmann rearrangement of oximes, the Schmidt reaction of cyclic ketones and hydrazoic acid, the Kinugasa reaction of nitrones and terminal acetylenes, the Diels-Alder reaction of cyclopentadiene and chlorosulfonyl isocyanate, transition metal catalyzed lactamization of amino alcohols, and iodolactamization of amides and alkenes. In particular, the intramolecular Staudinger ligation of azides and activated carboxy acids, including esters, is well known as an environmentally friendly and mild protocol for lactam synthesis

Antibiotic resistance patterns and beta-lactamase identification in ...

African Journals Online (AJOL)

Children acquire bacteria from their mother during birth,[3,4] and ... Our results revealed high resistance rates to co-trimoxazole (54.0%), penicillin .... the inclusion of a beta-lactamase inhibitor, clavulanic acid. .... Folate pathway inhibitor/.

Evaluation of prevalence of low and high level mupirocin resistance in methicillin resistant staphylococcus aureus isolates at a tertiary care hospital

International Nuclear Information System (INIS)

Nizamuddin, S.; Irfan, S.; Zafar, A.

2011-01-01

To evaluate the trend of mupirocin resistance in MRSA, isolated at the Clinical Microbiology Laboratory of a tertiary care hospital. Methods: A total of 200 MRSA strains recovered over a 2 year period from various body sites were tested using the 5 and 200 mu g discs of mupirocin to detect its resistance. Results: High level and low level mupirocin resistance were detected in zero and 1 % of MRSA strains, respectively. Resistance to other non beta lactam antibiotics was also high. No MRSA strains were found to be resistant to vancomycin and tegicycline. Conclusion: Mupirocin resistance was found to be very low among local clinical isolates of MRSA. Its judicious use to decolonize nasal carriers should be promoted among hospitalized patients to avoid further transmission and infections due to prevalent endemic MRSA strains in any health care setting. Concomitantly, regular surveillance and effective infection control initiatives are desirable to reduce the incidence of health care associated infections due to MRSA and also of mupirocin resistance. (author)

Comparative analyses of laccase-catalyzed amination reactions for production of novel β-lactam antibiotics.

Science.gov (United States)

Mikolasch, Annett; Manda, Katrin; Schlüter, Rabea; Lalk, Michael; Witt, Sabine; Seefeldt, Simone; Hammer, Elke; Schauer, Frieder; Jülich, Wolf-Dieter; Lindequist, Ulrike

2012-01-01

Seven novel β-lactam antibiotics with activities against Gram-positive bacterial strains, among them methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci, were synthesized by amination of 2,5-dihydroxyphenylacetic acid in usable yields (30-60%). These products protected mice against an infection with S. aureus lethal to the control animals. The results show the usefulness of laccase for the synthesis of potential new antibiotics, in addition to the interdependence of the laccase substrates, the amino coupling partners, and the product formation, yield, and activity. The syntheses of β-lactam antibiotics with 2,5-dihydroxyaromatic acid substructures (para-substituted) are then compared with those of 3,4-dihydroxyaromatic acid substructures (ortho-substituted). Para-substituted laccase substrates were better reaction partners in these syntheses than ortho-substituted compounds. Copyright © 2012 International Union of Biochemistry and Molecular Biology, Inc.

Phenotypic Characterization of Multidrug-resistant Escherichia Coli with Special Reference to Extended-spectrum-beta-lactamases and Metallo-beta-lactamases in a Tertiary Care Center

Directory of Open Access Journals (Sweden)

Basudha Shrestha

2015-06-01

Conclusions: Beta-lactamase mediated resistance mechanisms are accounting very high in the multidrug resistant isolates of E. coli. Therefore, early detection of beta lactamase mediated resistant strains and their current antibiotic susceptibility pattern is necessary to avoid treatment failure and prevent the spread of MDR. Keywords: e. coli; extended-spectrum-β-lactamase; metallo-β-lactamase; multidrug-resistance.

Breast abscess caused by penicillin resistant Pneumococci

Directory of Open Access Journals (Sweden)

Boppe Appalaraju

2011-01-01

Full Text Available Breast abscess is mostly caused by Staphylococcus aureus. A 26-year-old immunocompetent lady was admitted with breast abscess. Incision and drainage (I/D was done and Pneumococci were isolated from the drained pus. The patient was earlier treated with Augmentin which was later changed to linezolid after testing for antibiotic susceptibility. This strain showed a high level of resistance to penicillin. It had been noticed that there was a slow increase in the number of penicillin resistant Pneumococci isolated in our hospitals. The increase in penicillin-resistant Pneumococci correlates with the intensive use of beta-lactam antibiotics. Hence, antibiotics should be used judiciously, avoiding their use particularly in mild self-limiting upper respiratory infections. Attention therefore, should focus on monitoring resistance in Pneumococci to prevent mortality and morbidity associated with this organism, which continues to take a heavy toll on children and the elderly.

Sub-inhibitory cefsulodin sensitization of E. coli to β-lactams is mediated by PBP1b inhibition.

Directory of Open Access Journals (Sweden)

Sujoy K Sarkar

Full Text Available The combination of antibiotics is one of the strategies to combat drug-resistant bacteria, though only a handful of such combinations are in use, such as the β-lactam combinations. In the present study, the efficacy of a specific sub-inhibitory concentration of cefsulodin with other β-lactams was evaluated against a range of Gram-negative clinical isolates. This approach increased the sensitivity of the isolates, regardless of the β-lactamase production. The preferred target and mechanism of action of cefsulodin were identified in laboratory strains of Escherichia coli, by examining the effects of deleting the penicillin-binding protein (PBP 1a and 1b encoding genes individually. Deletion of PBP1b was involved in sensitizing the bacteria to β-lactam agents, irrespective of its O-antigen status. Moreover, the use of a sub-inhibitory concentration of cefsulodin in combination with a β-lactam exerted an effect similar to that one obtained for PBP1b gene deletion. We conclude that the identified β-lactam/cefsulodin combination works by inhibiting PBP1b (at least partially despite the involvement of β-lactamases, and therefore could be extended to a broad range of Gram-negative pathogens.

Surveillance of multidrug resistant suppurative infection causing bacteria in hospitalized patients in an Indian tertiary care hospital

OpenAIRE

Nabakishore Nayak; Rajesh K. Lenka; Rabindra N. Padhy

2014-01-01

Objective: To examine antibiograms of a cohort of suppurative bacteria isolated from wound-swabs from hospitalized patients of all economic groups of a typical Indian teaching hospital. Methods: In surveillance, antibiotic resistance patterns of 10 species of suppurative bacteria isolated from wound-swabs over a period of 24 months were recorded. Those were subjected to antibiotic sensitivity test, using 16 prescribed antibiotics of 5 different groups (3 aminoglycosides, 4 beta-lactams, 3 ...

WCK 5107 (Zidebactam) and WCK 5153 Are Novel Inhibitors of PBP2 Showing Potent “β-Lactam Enhancer” Activity against Pseudomonas aeruginosa, Including Multidrug-Resistant Metallo-β-Lactamase-Producing High-Risk Clones

Science.gov (United States)

Barcelo, Isabel M.; Bhagwat, Sachin; Patel, Mahesh; Bou, German; Papp-Wallace, Krisztina M.; Bonomo, Robert A.; Oliver, Antonio

2017-01-01

ABSTRACT Zidebactam and WCK 5153 are novel β-lactam enhancers that are bicyclo-acyl hydrazides (BCH), derivatives of the diazabicyclooctane (DBO) scaffold, targeted for the treatment of serious infections caused by highly drug-resistant Gram-negative pathogens. In this study, we determined the penicillin-binding protein (PBP) inhibition profiles and the antimicrobial activities of zidebactam and WCK 5153 against Pseudomonas aeruginosa, including multidrug-resistant (MDR) metallo-β-lactamase (MBL)-producing high-risk clones. MIC determinations and time-kill assays were conducted for zidebactam, WCK 5153, and antipseudomonal β-lactams using wild-type PAO1, MexAB-OprM-hyperproducing (mexR), porin-deficient (oprD), and AmpC-hyperproducing (dacB) derivatives of PAO1, and MBL-expressing clinical strains ST175 (blaVIM-2) and ST111 (blaVIM-1). Furthermore, steady-state kinetics was used to assess the inhibitory potential of these compounds against the purified VIM-2 MBL. Zidebactam and WCK 5153 showed specific PBP2 inhibition and did not inhibit VIM-2 (apparent Ki [Ki app] > 100 μM). MICs for zidebactam and WCK 5153 ranged from 2 to 32 μg/ml (amdinocillin MICs > 32 μg/ml). Time-kill assays revealed bactericidal activity of zidebactam and WCK 5153. LIVE-DEAD staining further supported the bactericidal activity of both compounds, showing spheroplast formation. Fixed concentrations (4 or 8 μg/ml) of zidebactam and WCK 5153 restored susceptibility to all of the tested β-lactams for each of the P. aeruginosa mutant strains. Likewise, antipseudomonal β-lactams (CLSI breakpoints), in combination with 4 or 8 μg/ml of zidebactam or WCK 5153, resulted in enhanced killing. Certain combinations determined full bacterial eradication, even with MDR MBL-producing high-risk clones. β-Lactam–WCK enhancer combinations represent a promising β-lactam “enhancer-based” approach to treat MDR P. aeruginosa infections, bypassing the need for MBL inhibition. PMID:28289035

Antibiotic Resistance Patterns in Invasive Group B Streptococcal Isolates

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Mei L. Castor

2008-01-01

Full Text Available Antibiotics are used for both group B streptococcal (GBS prevention and treatment. Active population-based surveillance for invasive GBS disease was conducted in four states during 1996—2003. Of 3813 case-isolates, 91.0% (3471 were serotyped, 77.1% (2937 had susceptibility testing, and 46.6% (3471 had both. All were sensitive to penicillin, ampicillin, cefazolin, cefotaxime, and vancomycin. Clindamycin and erythromycin resistance was 12.7% and 25.6%, respectively, and associated with serotype V (P<.001. Clindamycin resistance increased from 10.5% to 15.0% (X2 for trend 12.70; P<.001; inducible clindamycin resistance was associated with the erm genotype. Erythromycin resistance increased from 15.8% to 32.8% (X2 for trend 55.46; P<.001. While GBS remains susceptible to beta-lactams, resistance to alternative agents such as erythromycin and clindamycin is an increasing concern.

11beta-hydroxysteroid dehydrogenase type 1 regulates glucocorticoid-induced insulin resistance in skeletal muscle.

LENUS (Irish Health Repository)

Morgan, Stuart A

2009-11-01

Glucocorticoid excess is characterized by increased adiposity, skeletal myopathy, and insulin resistance, but the precise molecular mechanisms are unknown. Within skeletal muscle, 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) converts cortisone (11-dehydrocorticosterone in rodents) to active cortisol (corticosterone in rodents). We aimed to determine the mechanisms underpinning glucocorticoid-induced insulin resistance in skeletal muscle and indentify how 11beta-HSD1 inhibitors improve insulin sensitivity.

Occurrence, species distribution, antimicrobial resistance and clonality of methicillin- and erythromycin-resistant staphylococci in the nasal cavity of domestic animals

DEFF Research Database (Denmark)

Bagcigil, Funda A.; Moodley, Arshnee; Baptiste, Keith E.

2007-01-01

beta-Lactams and macrolides are important antibiotics for treatment of staphylococcal infections in both humans and animals. The aim of the study was to investigate the occurrence, species distribution and clonality of methicillin and erythromycin-resistant staphylococci in the nasal cavity of dogs......, horses, pigs, and cattle in Denmark. Nasal swabs were collected from a total of 400 animals, including 100 individuals of each species. Methicillin and erythromycin-resistant staphylococci were isolated on selective media, identified by 16S rDNA sequencing, and typed by pulsed field gel electrophoresis...... (PFGE). Methicillin-resistant coagulase-negative staphylococci (MRCoNS) harbouring mecA were isolated from horses (50%) and dogs (13%), but not from food animals. The species identified were S. haemolyticus (n = 21), S. vitulinus (n = 19), S. sciuri (n = 13), S. epidermidis (n = 8), and S. warneri (n...

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

Science.gov (United States)

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

2015-03-13

-acquired UTI due to PMACBL-producing E. coli were neither hospitalised nor had any antimicrobial treatment in the previous 6 months. The prevalence of PMACBL-producing E. coli was relatively low in the Auckland community, but has increased in recent years. Typing revealed that the majority of the PMACBL-producing E. coli in the Auckland region were genetically unrelated meaning that a point source or direct person to person transmission are not drivers of local community spread currently. The isolates were more resistant to non-beta-lactam antimicrobials than other non-AmpC, non-ESBL-producing E. coli, leaving few treatment options. The majority of the PMACBL-producing E. coli isolates seemed to be acquired in the community and were most frequently isolated from women with UTI. A large proportion of patients with community-acquired UTI had not been hospitalised nor had any antimicrobial treatment in the previous 6 months.

Structural studies on New Delhi Metallo-β-lactamase (NDM-2) suggest old β-lactam, penicillin to be better antibiotic for NDM-2-harbouring Acinetobacter baumanni.

Science.gov (United States)

Tiwari, Vishvanath; Moganty, Rajeswari R

2013-01-01

Acinetobacter baumannii, a Gram-negative pathogen causes nosocomial infections including pneumonia, urinary tract and respiratory infections. Carbapenem group of β-lactam antibiotics are routinely used to treat A. baumannii including multidrug-resistant clinical strains. The emergence of New Delhi Metallo-β-lactamase (NDM-2), a new type of β-lactamase and one of the major resistant determinants in A. baumannii, opened up challenges in the treatment of resistant strains. Thus, understanding the structure-function relationship of NDM-2 with different analogues of β-lactams becomes crucial. We carried out in silico studies on the interaction of various β-lactams with NDM-2 and with OXA-24, a carbapenem hydrolyzing non-NDM type β-lactamase. The binding affinity of the β-lactams to NDM-2 was found to be in the order: ceftazidime ≈ imipenem ≈ doripenem > oxacillin > aztreonam > penicillin; however, the order of their affinity to OXA-24 was quite different: ceftazidime > aztreonam > penicillin > oxacillin > doripenem > imipenem. Further, NDM-2 in comparison to OXA-24 showed stronger interaction (less X-score) with most of the β-lactams except penicillin. This suggests higher lethality posed by clinical strains expressing NDM-2 than those without NDM-2. Weak interaction between NDM-2 and penicillin clearly points out that penicillin is perhaps better option in treating A. baumannii harbouring NDM-2. Present findings provide new insights in drug resistance at the molecular level of NDM-2 and can help in designing structure-based drugs.

Molecular characterization of four beta-tubulin genes from dinitroaniline susceptible and resistant biotypes of Eleusine indica.

Science.gov (United States)

Yamamoto, E; Baird, W V

1999-01-01

Dinitroaniline herbicides are antimicrotubule drugs that bind to tubulins and inhibit polymerization. As a result of repeated application of dinitroaniline herbicides, resistant biotypes of goosegrass (Eleusine indica) developed in previously susceptible wild-type populations. We have previously reported that alpha-tubulin missense mutations correlate with dinitroaniline response phenotypes (Drp) (Plant Cell 10: 297-308, 1998). In order to ascertain associations of other tubulins with dinitroaniline resistance, four beta-tubulin cDNA classes (designated TUB1, TUB2, TUB3, and TUB4) were isolated from dinitroaniline-susceptible and -resistant biotypes. Sequence analysis of the four beta-tubulin cDNA classes identified no missense mutations. Identified nucleotide substitutions did not result in amino acid replacements. These results suggest that the molecular basis of dinitroaniline resistance in goosegrass differs from those of colchicine/dinitroaniline cross-resistant Chlamydomonas reinhardtii and benzimidazole-resistant fungi and yeast. Expression of the four beta-tubulins was highest in inflorescences. This is in contrast to alpha-tubulin TUA1 that is expressed predominantly in roots. Collectively, these results imply that beta-tubulin genes are not associated with dinitroaniline resistance in goosegrass. Phylogenetic analysis of the four beta-tubulins, together with three alpha-tubulins, suggests that the resistant biotype developed independently in multiple locations rather than spreading from one location.

Chronological Change of Resistance to β-Lactams in Salmonella enterica serovar Infantis Isolated from Broilers in Japan.

Science.gov (United States)

Chuma, Takehisa; Miyasako, Daisuke; Dahshan, Hesham; Takayama, Tomoko; Nakamoto, Yuko; Shahada, Francis; Akiba, Masato; Okamoto, Karoku

2013-01-01

Epidemiologic surveillance study was conducted in southern Japan to determine the antimicrobial resistance phenotypes and characterize the β-lactamase genes and the plasmids harboring these genes in Salmonella enterica serovar Infantis (S. Infantis) isolates from broilers. Between January, 2007 and December, 2008, a total of 1,472 fecal samples were collected and examined at the Laboratory of Veterinary Public Health, Kagoshima University, Japan. In 93 (6.3%) isolates recovered, 33 (35.5%) isolates showed resistance to cefotaxime, an extended-spectrum cephalosporin (ESC), conferred by TEM-20, TEM-52 and CTX-M-25 extended-spectrum β-lactamases (ESBLs). In addition to ESC-resistance, eight (8.6%) isolates exhibited resistance to cefoxitin mediated by CMY-2 AmpC β-lactamase. Plasmid analysis and polymerase chain reaction replicon typing revealed the bla TEM-20 and bla CMY-2 genes were associated with IncP plasmids, bla TEM-52 was linked with a non-typable plasmid and bla CTX-M-25 was carried by an IncA/C plasmid. Non-β-lactam resistance to streptomycin, sulfamethoxazole, and oxytetracycline encoded by the aadA1, sul1, and tet(A) genes, respectively, was found in 86 (92.5%) isolates. Resistance to kanamycin and ofloxacin was exhibited in 12 (12.9%) and 11 (11.8%) isolates, respectively, the former was mediated by aphA1-Iab. These data indicate that S. Infantis isolates producing ESBLs and AmpC β-lactamase have spread among broiler farms in Japan. These data demonstrated that the incidence of ESC-resistant S. Infantis carrying bla TEM-52 remarkably increased and S. Infantis strains harboring bla CMY-2, bla TEM-20, or bla CTX-M-25 genes emerged from broilers in Japan for the first time in 2007 and 2008.

MRJP1-containing glycoproteins isolated from honey, a novel antibacterial drug candidate with broad spectrum activity against multi-drug resistant clinical isolates

Directory of Open Access Journals (Sweden)

Katrina eBrudzynski

2015-07-01

Full Text Available The emergence of extended- spectrum β-lactamase (ESBL is the underlying cause of growing antibiotic resistance among Gram-negative bacteria to β-lactam antibiotics. We recently reported the discovery of honey glycoproteins (glps that exhibited a rapid, concentration-dependent antibacterial activity against both Gram-positive Bacillus subtilis and Gram-negative Escherichia coli that resembled action of cell wall-active β-lactam drugs. Glps showed sequence identity with the Major Royal Jelly Protein 1 (MRJP1 precursor that harbors three antimicrobial peptides: Jelleins 1, 2 and 4. Here, we used semi-quantitative radial diffusion assay and broth microdilution assay to evaluate susceptibility of a number of multi-drug resistant (MDR clinical isolates to the MRJP1-contaning honey glycoproteins. The MDR bacterial strains comprised 3 MRSA, 4 Pseudomonas aeruginosa, 2 Klebsiella pneumoniae, 2 VRE and 5 Extended-spectrum beta-lactamase (ESBL identified as 1 Proteus mirabilis, 3 Escherichia coli and 1 Escherichia coli NDM. Their resistance to different classes of antibiotics was confirmed using automated system Vitek 2. MDR isolates differred in their susceptibility to glps with MIC90 values ranging from 4.8μg/ml against B. subtilis to 14.4μg/ml against ESBL K. pneumoniae, Klebsiella spp ESBL and E. coli and up to 33μg/ml against highly resistant strains of P. aeruginosa. Glps isolated from different honeys showed a similar ability to overcome bacterial resistance to β-lactams suggesting that (a their mode of action is distinct from other classes of β-lactams and that (b the common glps structure was the lead structure responsible for the activity. The results of the current study together with our previous evidence of a rapid bactericidal activity of glps demonstrate that glps possess suitable characteristics to be considered a novel antibacterial drug candidate.

Public transport as a reservoir of methicillin-resistant staphylococci.

Science.gov (United States)

Stepanović, S; Cirković, I; Djukić, S; Vuković, D; Svabić-Vlahović, M

2008-10-01

The aim of this study was to explore the occurrence of methicillin-resistant staphylococci in a large urban public transport system. Samples were taken from hand rails, which passengers hold onto when they are standing. In total, 1400 swabs taken from 55 vehicles (trolleybuses, trams and buses) were examined. As many as 30.1% samples were positive for the presence of methicillin-resistant coagulase-negative staphylococci (MRCoNS), but none for methicillin-resistant Staphylococcus aureus (MRSA). MRCoNS were isolated from all 55 vehicles. Nearly 50% of MRCoNS isolates displayed resistance not only to beta-lactams, but at least to two or more other classes of antimicrobials as well. This study demonstrated widespread occurrence of MRCoNS on hand rails in public transport vehicles. MRSA was not detected. The recovery of methicillin-resistant staphylococci from public transport system implies a potential risk for transmission of these bacteria in an out-hospital environment.

Antimicrobial resistance mechanisms among Campylobacter.

Science.gov (United States)

Wieczorek, Kinga; Osek, Jacek

2013-01-01

Campylobacter jejuni and Campylobacter coli are recognized as the most common causative agents of bacterial gastroenteritis in the world. Humans most often become infected by ingesting contaminated food, especially undercooked chicken, but also other sources of bacteria have been described. Campylobacteriosis is normally a self-limiting disease. Antimicrobial treatment is needed only in patients with more severe disease and in those who are immunologically compromised. The most common antimicrobial agents used in the treatment of Campylobacter infections are macrolides, such as erythromycin, and fluoroquinolones, such as ciprofloxacin. Tetracyclines have been suggested as an alternative choice in the treatment of clinical campylobacteriosis but in practice are not often used. However, during the past few decades an increasing number of resistant Campylobacter isolates have developed resistance to fluoroquinolones and other antimicrobials such as macrolides, aminoglycosides, and beta-lactams. Trends in antimicrobial resistance have shown a clear correlation between use of antibiotics in the veterinary medicine and animal production and resistant isolates of Campylobacter in humans. In this review, the patterns of emerging resistance to the antimicrobial agents useful in treatment of the disease are presented and the mechanisms of resistance to these drugs in Campylobacter are discussed.

Determination of Insulin Resistance and Beta Cell Function in Healthy Obese and Non-obese Individuals

International Nuclear Information System (INIS)

Kazmi, A.; Sattar, A.; Tariq, K. M.; Najamussahar; Hashim, R.; Almani, M. I.

2013-01-01

Objective: To determine insulin resistance and beta cell function in healthy obese and nonobese individuals of the local population. Study Design: Case control study. Place and Duration of Study: AFIP Rawalpindi in collaboration with department of medicine military hospital(MH) Rawalpindi, from Aug 2008 to Mar 2009. Methods: Eighty obese(n=40) and non-obese(n=40) subjects were selected by non-probability convenience sampling. Plasma insulin, glucose, and serum total cholestrol were estimated in fasting state. Insulin resistance was calculated by HOMA-IR and beta cell function by HOMA- equation. Results: Significant differences were observed between obese and non-obese individuals regarding insulin resistance, beta cell function, and BMI and serum total cholesterol. Mean insulin resistance in obese group was found to be 11.1 +- 5.1(range 7.0-16.2) and in non-obese group it was 0.9+-0.4 (range 0.5-1.3). This difference was highly significant (p=0.001). There was a highly significant difference between the two groups in term of beta cell function with mean rank 60.1 for obese group and 20.9 non obese groups (Asym sig. 2 tailed 0.000). Also the correlation (r = 0.064) between insulin resistance and beta cell function in obese group is highly significant (p = 0.000). Mean serum leptin levels were lower (6.3 ng/ml) in non-obese, and high (57.2 ng/ml) in the obese group. Conclusions: Insulin resistance is found higher in obese individuals. Beta cell function is significantly different between obese and non-obese groups. (author)

In silico analysis of different generation β lactams antibiotics with penicillin binding protein-2 of Neisseria meningitidis for curing meningococcal disease.

Science.gov (United States)

Tripathi, Vijay; Tripathi, Pooja; Srivastava, Navita; Gupta, Dwijendra

2014-12-01

Neisseria meningitidis is a gram negative, diplococcic pathogen responsible for the meningococcal disease and fulminant septicemia. Penicillin-binding proteins-2 (PBPs) is crucial for the cell wall biosynthesis during cell proliferation of N. meningitidis and these are the target for β-lactam antibiotics. For many years penicillin has been recognized as the antibiotic for meningococcal disease but the meningococcus has seemed to be antibiotic resistance. In the present work we have verified the molecular interaction of Penicillin binding protein-2 N. meningitidis to different generation of β-lactam antibiotics and concluded that the third generation of β-lactam antibiotics shows efficient binding with Penicillin binding protein-2 of N. meningitidis. On the basis of binding efficiency and inhibition constant, ceftazidime emerged as the most efficient antibiotic amongst the other advanced β-lactam antibiotics against Penicillin-binding protein-2 of N. meningitidis.

In vitro activity of three different antimicrobial agents against ESBL producing Escherichia coli and Klebsiella pneumoniae blood isolates.

Science.gov (United States)

Kizirgil, Ahmet; Demirdag, Kutbettin; Ozden, Mehmet; Bulut, Yasemin; Yakupogullari, Yusuf; Toraman, Zulal Asci

2005-01-01

Extended spectrum beta-lactamases (ESBLs) usually associated with multiple drug resistance, including beta-lactam and non-beta-lactam antibiotics. This resistance can cause Limitation in the choice of drugs appropriate for using in clinical practice, especially in life-threatening infections. In this study we aimed to investigate in vitro activity of meropenem, ciprofloxacine and amikacin against ESBL-producing and non-producing blood isolates of Escherichia coli and Klebsiella pneumoniae strains. Fifty-eight E. coli (21 ESBL-producing, 37 non-ESBL producing) and 99 K. pneumoniae (54 ESBL-producing, 45 non-ESBL producing) strains were included in the study. The presence of ESBL was investigated by double disk synergy test and E-test methods. Antibiotic susceptibility test was done by microdilution method according to NCCLS guideline. In vitro susceptibilities of ESBL producing E. coli and K. pneumoniae strains were found as 100% for meropenem, 33.3% and 25.9% for ciprofloxacine, 94.5% and 83.3% for amikacin. It was observed that; meropenem was equally active agent in both ESBL-producing and non-producing strains, and its activity was not affected by ESBL production. Whereas amikacin activity was minimally affected and ciprofloxacine activity was markedly decreased by ESBL production. In conclusion, meropenem seems to be better choice of antibiotic should be used for ESBL positive life-threatening infections, because of remaining highest activity.

Reconceptualizing resistance: sociology and the affective dimension of resistance.

Science.gov (United States)

Hynes, Maria

2013-12-01

This paper re-examines the sociological study of resistance in light of growing interest in the concept of affect. Recent claims that we are witness to an 'affective turn' and calls for a 'new sociological empiricism' sensitive to affect indicate an emerging paradigm shift in sociology. Yet, mainstream sociological study of resistance tends to have been largely unaffected by this shift. To this end, this paper presents a case for the significance of affect as a lens by which to approach the study of resistance. My claim is not simply that the forms of actions we would normally recognize as resistance have an affective dimension. Rather, it is that the theory of affect broadens 'resistance' beyond the purview of the two dominant modes of analysis in sociology; namely, the study of macropolitical forms, on the one hand, and the micropolitics of everyday resistance on the other. This broadened perspective challenges the persistent assumption that ideological forms of power and resistance are the most pertinent to the contemporary world, suggesting that much power and resistance today is of a more affective nature. In making this argument, it is a Deleuzian reading of affect that is pursued, which opens up to a level of analysis beyond the common understanding of affect as emotion. I argue that an affective approach to resistance would pay attention to those barely perceptible transitions in power and mobilizations of bodily potential that operate below the conscious perceptions and subjective emotions of social actors. These affective transitions constitute a new site at which both power and resistance operate. © London School of Economics and Political Science 2013.

Características de la resistencia antimicrobiana de una colección clínica de Strptococcus pyogenes Antimicrobial resistance of Streptococcus pyogenes clinical strains

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Romeo S. Rodríguez

2000-06-01

Full Text Available OBJETIVO: Determinar la susceptibilidad antimicrobiana de Streptococcus pyogenes con el fin de estimar la prevalencia de los fenotipos de resistencia a los macrólidos. MATERIAL Y MÉTODOS: Se realizó un estudio de tipo transversal, en 1999, en el que se evaluaron 100 cepas de S. pyogenes, aislados en el Hospital Infantil de México Federico Gómez, en el lapso comprendido entre 1992 y 1998, procedentes de niños con faringoamigdalitis, conservadas en congelación en el laboratorio de bacteriología hasta su procesamiento. Se determinó la susceptibilidad antimicrobiana a algunos beta-lactámicos, macrólidos y clindamicina. La resistencia a eritromicina se probó por medio de la prueba de difusión de doble disco. Se calcularon medidas de tendencia central. RESULTADOS: Todas las cepas fueron sensibles a los beta-lactámicos y clindamicina; 16% fueron resistentes a los macrólidos, y todas correspondieron al fenotipo M. CONCLUSIONES: Es conveniente realizar periódicamente pruebas de escrutinio para conocer los posibles cambios en los patrones de sensibilidad estreptocócica.OBJECTIVE: To determine the antibiotic susceptibility of recent isolates of Streptococcus pyogenes and to evaluate the prevalence of macrolide-resistant phenotypes. MATERIAL AND METHODS: In 1999, we conducted a cross-sectional study at Mexico Children's Hospital "Federico Gomez", to analyze one hundred strains of S. pyogenes isolated from 1992 to 1998, in children with uncomplicated pharyngotonsillitis. Strains were frozen at the bacteriology lab until they were analyzed. Strains were tested for susceptibility against some beta-lactams, macrolides and clindamycin. Double-disk testing was carried out to evaluate erythromycin-resistant phenotypes. Data are presented using central tendency measures. RESULTS: All tested strains were not resistant to beta-lactams and clindamycin; 16% of the strains were resistant to macrolides and all of them belonged to phenotype M. CONCLUSIONS

Penicillin and Beta-Lactam Hypersensitivity.

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Har, Daniel; Solensky, Roland

2017-11-01

Ten percent of patients report penicillin allergy, but more than 90% of these individuals can tolerate penicillins. Skin testing remains the optimal method for evaluation of possible IgE-mediated penicillin allergy and is recommended by professional societies, as the harms for alternative antibiotics include antimicrobial resistance, prolonged hospitalizations, readmissions, and increased costs. Removal of penicillin allergy leads to decreased utilization of broad-spectrum antibiotics, such as fluoroquinolones and vancomycin. There is minimal allergic cross-reactivity between penicillins and cephalosporins. IgE-mediated allergy to cephalosporins is usually side-chain specific and may warrant graded challenge with cephalosporins containing dissimilar R1 or R2 group side chains. Copyright © 2017 Elsevier Inc. All rights reserved.

Extended spectrum β-lactamase producing Escherichia coli and Klebsiella pneumoniae: critical tools for antibiotic resistance pattern.

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Padmini, Nagarajan; Ajilda, Antony Alex Kennedy; Sivakumar, Natesan; Selvakumar, Gopal

2017-06-01

Drug resistance is a phenomenon where by an organism becomes fully or partially resistant to drugs or antibiotics being used against it. Antibiotic resistance poses an exacting intimidation for people with underlying medical immune conditions or weakened immune systems. Infections caused by the enzyme extended spectrum β-lactamase (ESBL) producing multi drug resistance (MDR) Enterobacteriaceae especially Escherichia coli and Klebsiella pneumoniae are resistant to a broad range of beta lactams, including third generation cephalosporins. Among all the pathogens, these two MDR E. coli and K. pneumoniae have emerged as one of the world's greatest health threats in past two decades. The nosocomial infections caused by these ESBL producing MDR E. coli and K. pneumoniae complicated the therapy and limit treatment options. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Anti-tuberculosis activity of -lactam antibiotics: prospects for the ...

African Journals Online (AJOL)

This review is prepared to show results on the anti-TB activity of -lactam antibiotics. -Lactams are among the oldest drugs with little or no side effects. Both in vitro studies and clinical data indicate that -lactams have a promising activity for use in the management of MDR-TB. More studies are required to define the interaction ...

Impact of the β-Lactam Resistance Modifier (−-Epicatechin Gallate on the Non-Random Distribution of Phospholipids across the Cytoplasmic Membrane of Staphylococcus aureus

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Helena Rosado

2015-07-01

Full Text Available The polyphenol (−-epicatechin gallate (ECg inserts into the cytoplasmic membrane (CM of methicillin-resistant Staphylococcus aureus (MRSA and reversibly abrogates resistance to β-lactam antibiotics. ECg elicits an increase in MRSA cell size and induces thickened cell walls. As ECg partially delocalizes penicillin-binding protein PBP2 from the septal division site, reduces PBP2 and PBP2a complexation and induces CM remodelling, we examined the impact of ECg membrane intercalation on phospholipid distribution across the CM and determined if ECg affects the equatorial, orthogonal mode of division. The major phospholipids of the staphylococcal CM, lysylphosphatidylglycerol (LPG, phosphatidylglycerol (PG, and cardiolipin (CL, were distributed in highly asymmetric fashion; 95%–97% of LPG was associated with the inner leaflet whereas PG (~90% and CL (~80% were found predominantly in the outer leaflet. ECg elicited small, significant changes in LPG distribution. Atomic force microscopy established that ECg-exposed cells divided in similar fashion to control bacteria, with a thickened band of encircling peptidoglycan representing the most recent plane of cell division, less distinct ribs indicative of previous sites of orthogonal division and concentric rings and “knobbles” representing stages of peptidoglycan remodelling during the cell cycle. Preservation of staphylococcal membrane lipid asymmetry and mode of division in sequential orthogonal planes appear key features of ECg-induced stress.

Infusional β-lactam antibiotics in febrile neutropenia: has the time come?

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Abbott, Iain J; Roberts, Jason A

2012-12-01

Febrile neutropenia presents a clinical challenge in which timely and appropriate antibiotic exposure is crucial. In the context of altered pharmacokinetics and rising bacterial resistance, standard antibiotic doses are unlikely to be sufficient. This review explores the potential utility of altered dosing approaches of β-lactam antibiotics to optimize treatment in febrile neutropenia. There is a dynamic relationship between the antibiotic, the infecting pathogen, and the host. Great advancements have been made in the understanding of the pharmacokinetic changes in critical illness and the pharmacodynamic relationships of antibiotics in these settings. Antibiotic treatment in febrile neutropenia is becoming increasingly difficult. Patients are of higher acuity, receive more intensive chemotherapy regimens leading to prolonged neutropenia, and are often exposed to multiple antibiotic courses. These patients display significant variability in antibiotic clearances and increases in volume of distribution compared with standard ward-based patients. Rising antibiotic resistance and a lack of new antibiotics in production have prompted alternative dosing strategies based on pharmacokinetic/pharmacodynamic data, such as extended or continuous infusions of β-lactam antibiotics, to maximize the likelihood of treatment success. A definitive study that describes a mortality benefit of such dosing regimens remains elusive and the theoretical advantages require testing in well designed clinical trials.

In Vitro Synergistic Effects of Double and Triple Combinations of β-Lactams, Vancomycin, and Netilmicin against Methicillin-Resistant Staphylococcus aureus Strains

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Rochon-Edouard, Stéphanie; Pestel-Caron, Martine; Lemeland, Jean-François; Caron, François

2000-01-01

Several studies have previously reported synergistic effects between vancomycin and a given β-lactam or a given aminoglycoside against methicillin-resistant Staphylococcus aureus (MRSA) strains. The aim of our study was to exhaustively compare the effects of different combinations of a β-lactam, vancomycin, and/or an aminoglycoside against 32 clinical MRSA strains with different aminoglycoside susceptibility patterns. The effects of 26 different β-lactam–vancomycin and 8 different aminoglycoside-vancomycin combinations were first studied using a disk diffusion screening method. The best interactions with vancomycin were observed with either imipenem, cefazolin, or netilmicin. By checkerboard studies, imipenem-vancomycin and cefazolin-vancomycin each provided a synergistic bacteriostatic effect against 22 strains; the mean fractional inhibitory concentration (FIC) indexes were 0.35 and 0.46 for imipenem-vancomycin and cefazolin-vancomycin, respectively. The vancomycin-netilmicin combination provided an indifferent effect against all of the 32 strains tested; the mean of FIC index was 1.096. The mean concentrations of imipenem, cefazolin, netilmicin, and vancomycin at which FIC indexes were calculated were clinically achievable. Killing experiments were then performed using imipenem, cefazolin, netilmicin, and vancomycin at one-half of the MIC, alone and in different combinations, against 10 strains. The vancomycin-netilmicin regimen was rarely bactericidal, even against strains susceptible to netilmicin. The imipenem-vancomycin and cefazolin-vancomycin combinations were strongly bactericidal against six and five strains, respectively. The addition of netilmicin markedly enhanced the killing activity of the combination of cefazolin or imipenem plus vancomycin, but only for the MRSA strains against which the β-lactam–vancomycin combinations had no bactericidal effect. It is noteworthy that the latter strains were both susceptible to netilmicin and

Identification of Mycobacterial Genes Involved in Antibiotic Sensitivity: Implications for the Treatment of Tuberculosis with β-Lactam-Containing Regimens

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Viswanathan, Gopinath; Yadav, Sangya

2017-01-01

ABSTRACT In a Mycobacterium smegmatis mutant library screen, transposon mutants with insertions in fhaA, dprE2, rpsT, and parA displayed hypersusceptibility to antibiotics, including the β-lactams meropenem, ampicillin, amoxicillin, and cefotaxime. Sub-MIC levels of octoclothepin, a psychotic drug inhibiting ParA, phenocopied the parA insertion and enhanced the bactericidal activity of meropenem against Mycobacterium tuberculosis in combination with clavulanate. Our study identifies novel factors associated with antibiotic resistance, with implications in repurposing β-lactams for tuberculosis treatment. PMID:28438925

Does prolonged β-lactam infusions improve clinical outcomes compared to intermittent infusions? A meta-analysis and systematic review of randomized, controlled trials

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Van Arendonk Kyle J

2011-06-01

Full Text Available Abstract Background The emergence of multi-drug resistant Gram-negatives (MDRGNs coupled with an alarming scarcity of new antibiotics has forced the optimization of the therapeutic potential of available antibiotics. To exploit the time above the minimum inhibitory concentration mechanism of β-lactams, prolonging their infusion may improve outcomes. The primary objective of this meta-analysis was to determine if prolonged β-lactam infusion resulted in decreased mortality and improved clinical cure compared to intermittent β-lactam infusion. Methods Relevant studies were identified from searches of MEDLINE, EMBASE, and CENTRAL. Heterogeneity was assessed qualitatively, in addition to I2 and Chi-square statistics. Pooled relative risks (RR and 95% confidence intervals (CI were calculated using Mantel-Haenszel random-effects models. Results Fourteen randomized controlled trials (RCTs were included. Prolonged infusion β-lactams were not associated with decreased mortality (n= 982; RR 0.92; 95% CI:0.61-1.37 or clinical cure (n = 1380; RR 1.00 95% CI:0.94-1.06 compared to intermittent infusions. Subgroup analysis for β-lactam subclasses and equivalent total daily β-lactam doses yielded similar results. Most studies had notable methodological flaws. Conclusions No clinical advantage was observed for prolonged infusion β-lactams. The limited number of studies with MDRGNs precluded evaluation of prolonged infusion of β-lactams for this subgroup. A large, multicenter RCT with critically ill patients infected with MDRGNs is needed.

Phenotypic and genomic comparisons of highly vancomycin-resistant Staphylococcus aureus strains developed from multiple clinical MRSA strains by in vitro mutagenesis.

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Ishii, Kenichi; Tabuchi, Fumiaki; Matsuo, Miki; Tatsuno, Keita; Sato, Tomoaki; Okazaki, Mitsuhiro; Hamamoto, Hiroshi; Matsumoto, Yasuhiko; Kaito, Chikara; Aoyagi, Tetsuji; Hiramatsu, Keiichi; Kaku, Mitsuo; Moriya, Kyoji; Sekimizu, Kazuhisa

2015-11-25

The development of vancomycin (VCM) resistance in Staphylococcus aureus threatens global health. Studies of the VCM-resistance mechanism and alternative therapeutic strategies are urgently needed. We mutagenized S. aureus laboratory strains and methicillin-resistant S. aureus (MRSA) with ethyl methanesulfonate, and isolated mutants that exhibited high resistance to VCM (minimum inhibitory concentration = 32 μg/ml). These VCM-resistant strains were sensitive to linezolid and rifampicin, and partly to arbekacin and daptomycin. Beta-lactams had synergistic effects with VCM against these mutants. VCM-resistant strains exhibited a 2-fold increase in the cell wall thickness. Several genes were commonly mutated among the highly VCM-resistant mutants. These findings suggest that MRSA has a potential to develop high VCM resistance with cell wall thickening by the accumulation of mutations.

Synergy of β-Lactams with Vancomycin against Methicillin-Resistant Staphylococcus aureus: Correlation of Disk Diffusion and Checkerboard Methods.

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Sy, Cheng Len; Huang, Tsi-Shu; Chen, Chii Shiang; Chen, Yao-Shen; Tsai, Hung-Chin; Wann, Shue-Renn; Wu, Kuan-Sheng; Chen, Jui-Kuang; Lee, Susan Shin-Jung; Liu, Yung-Ching

2016-03-01

Modified disk diffusion (MDD) and checkerboard tests were employed to assess the synergy of combinations of vancomycin and β-lactam antibiotics for 59 clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and Mu50 (ATCC 700699). Bacterial inocula equivalent to 0.5 and 2.0 McFarland standard were inoculated on agar plates containing 0, 0.5, 1, and 2 μg/ml of vancomycin. Oxacillin-, cefazolin-, and cefoxitin-impregnated disks were applied to the surface, and the zones of inhibition were measured at 24 h. The CLSI-recommended checkerboard method was used as a reference to detect synergy. The MICs for vancomycin were determined using the Etest method, broth microdilution, and the Vitek 2 automated system. Synergy was observed with the checkerboard method in 51% to 60% of the isolates when vancomycin was combined with any β-lactam. The fractional inhibitory concentration indices were significantly lower in MRSA isolates with higher vancomycin MIC combinations (P synergy in MRSA isolates with bacterial inocula equivalent to McFarland standard 0.5 were 33.0% and 62.5% for oxacillin, 45.1% and 52.4% for cefazolin, and 43.1% and 52.4% for cefoxitin when combined with 0.5 and 2 μg/ml of vancomycin, respectively. Based on our study, the simple MDD method is not recommended as a replacement for the checkerboard method to detect synergy. However, it may serve as an initial screening method for the detection of potential synergy when it is not feasible to perform other labor-intensive synergy tests. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Genetic Determinants of High-Level Oxacillin Resistance in Methicillin-Resistant Staphylococcus aureus.

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Pardos de la Gandara, Maria; Borges, Vitor; Chung, Marilyn; Milheiriço, Catarina; Gomes, João Paulo; de Lencastre, Herminia; Tomasz, Alexander

2018-06-01

Methicillin-resistant Staphylococcus aureus (MRSA) strains carry either a mecA - or a mecC -mediated mechanism of resistance to beta-lactam antibiotics, and the phenotypic expression of resistance shows extensive strain-to-strain variation. In recent communications, we identified the genetic determinants associated with the stringent stress response that play a major role in the antibiotic resistant phenotype of the historically earliest "archaic" clone of MRSA and in the mecC -carrying MRSA strain LGA251. Here, we sought to test whether or not the same genetic determinants also contribute to the resistant phenotype of highly and homogeneously resistant (H*R) derivatives of a major contemporary MRSA clone, USA300. We found that the resistance phenotype was linked to six genes ( fruB , gmk , hpt , purB , prsA , and relA ), which were most frequently targeted among the analyzed 20 H*R strains (one mutation per clone in 19 of the 20 H*R strains). Besides the strong parallels with our previous findings (five of the six genes matched), all but one of the repeatedly targeted genes were found to be linked to guanine metabolism, pointing to the key role that this pathway plays in defining the level of antibiotic resistance independent of the clonal type of MRSA. Copyright © 2018 American Society for Microbiology.

Functional characterization of the oxaloacetase encoding gene and elimination of oxalate formation in the beta-lactam producer Penicillium chrysogenum

NARCIS (Netherlands)

Gombert, A. K.; Veiga, T.; Puig-Martinez, M.; Lamboo, F.; Nijland, J. G.; Driessen, A. J. M.; Pronk, J. T.; Daran, J. M.

Penicillium chrysogenum is widely used as an industrial antibiotic producer, in particular in the synthesis of g-lactam antibiotics such as penicillins and cephalosporins. In industrial processes, oxalic acid formation leads to reduced product yields. Moreover, precipitation of calcium oxalate

A putative low-molecular-mass penicillin-binding protein (PBP) of Mycobacterium smegmatis exhibits prominent physiological characteristics of DD-carboxypeptidase and beta-lactamase.

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Bansal, Ankita; Kar, Debasish; Murugan, Rajagopal A; Mallick, Sathi; Dutta, Mouparna; Pandey, Satya Deo; Chowdhury, Chiranjit; Ghosh, Anindya S

2015-05-01

DD-carboxypeptidases (DD-CPases) are low-molecular-mass (LMM) penicillin-binding proteins (PBPs) that are mainly involved in peptidoglycan remodelling, but little is known about the dd-CPases of mycobacteria. In this study, a putative DD-CPase of Mycobacterium smegmatis, MSMEG_2433 is characterized. The gene for the membrane-bound form of MSMEG_2433 was cloned and expressed in Escherichia coli in its active form, as revealed by its ability to bind to the Bocillin-FL (fluorescent penicillin). Interestingly, in vivo expression of MSMEG_2433 could restore the cell shape oddities of the septuple PBP mutant of E. coli, which was a prominent physiological characteristic of DD-CPases. Moreover, expression of MSMEG_2433 in trans elevated beta-lactam resistance in PBP deletion mutants (ΔdacAdacC) of E. coli, strengthening its physiology as a dd-CPase. To confirm the biochemical reason behind such physiological behaviours, a soluble form of MSMEG_2433 (sMSMEG_2433) was created, expressed and purified. In agreement with the observed physiological phenomena, sMSMEG_2433 exhibited DD-CPase activity against artificial and peptidoglycan-mimetic DD-CPase substrates. To our surprise, enzymic analyses of MSMEG_2433 revealed efficient deacylation for beta-lactam substrates at physiological pH, which is a unique characteristic of beta-lactamases. In addition to the MSMEG_2433 active site that favours dd-CPase activity, in silico analyses also predicted the presence of an omega-loop-like region in MSMEG_2433, which is an important determinant of its beta-lactamase activity. Based on the in vitro, in vivo and in silico studies, we conclude that MSMEG_2433 is a dual enzyme, possessing both DD-CPase and beta-lactamase activities. © 2015 The Authors.

Documenting Penicillin Allergy: The Impact of Inconsistency

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Shah, Nirav S.; Ridgway, Jessica P.; Pettit, Natasha; Fahrenbach, John; Robicsek, Ari

2016-01-01

Background Allergy documentation is frequently inconsistent and incomplete. The impact of this variability on subsequent treatment is not well described. Objective To determine how allergy documentation affects subsequent antibiotic choice. Design Retrospective, cohort study. Participants 232,616 adult patients seen by 199 primary care providers (PCPs) between January 1, 2009 and January 1, 2014 at an academic medical system. Main Measures Inter-physician variation in beta-lactam allergy documentation; antibiotic treatment following beta-lactam allergy documentation. Key Results 15.6% of patients had a reported beta-lactam allergy. Of those patients, 39.8% had a specific allergen identified and 22.7% had allergic reaction characteristics documented. Variation between PCPs was greater than would be expected by chance (all ppenicillins”) (24.0% to 58.2%) and documentation of the reaction characteristics (5.4% to 51.9%). After beta-lactam allergy documentation, patients were less likely to receive penicillins (Relative Risk [RR] 0.16 [95% Confidence Interval: 0.15–0.17]) and cephalosporins (RR 0.28 [95% CI 0.27–0.30]) and more likely to receive fluoroquinolones (RR 1.5 [95% CI 1.5–1.6]), clindamycin (RR 3.8 [95% CI 3.6–4.0]) and vancomycin (RR 5.0 [95% CI 4.3–5.8]). Among patients with beta-lactam allergy, rechallenge was more likely when a specific allergen was identified (RR 1.6 [95% CI 1.5–1.8]) and when reaction characteristics were documented (RR 2.0 [95% CI 1.8–2.2]). Conclusions Provider documentation of beta-lactam allergy is highly variable, and details of the allergy are infrequently documented. Classification of a patient as beta-lactam allergic and incomplete documentation regarding the details of the allergy lead to beta-lactam avoidance and use of other antimicrobial agents, behaviors that may adversely impact care quality and cost. PMID:26981866

11beta-hydroxysteroid dehydrogenase type 1 in adipose tissue and prospective changes in body weight and insulin resistance

DEFF Research Database (Denmark)

Koska, Juraj; de Courten, Barbora; Wake, Deborah J

2006-01-01

Increased mRNA and activity levels of 11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD1) in human adipose tissue (AT) are associated with obesity and insulin resistance. The aim of our study was to investigate whether 11betaHSD1 expression or activity in abdominal subcutaneous AT of non-diab......-diabetic subjects are associated with subsequent changes in body weight and insulin resistance [homeostasis model assessment of insulin resistance (HOMA-IR)]....

Antibiotic sensitivity and resistance in Ornithobacterium rhinotracheale strains from Belgian broiler chickens.

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Devriese, L A; De Herdt, P; Haesebrouck, F

2001-06-01

Establishing the antibiotic sensitivity of the avian respiratory pathogen Ornithobacterium rhinotracheale is difficult because of the organism's complex growth requirements and the unusually frequent occurrence of resistance. The minimal inhibitory concentrations of 10 antibiotics were determined for 45 strains of O. rhinotracheale from Belgian broiler chickens collected from 45 farms between 1995 and 1998. They were compared with the type strain, which was isolated from a turkey, and a strain isolated from a rook. All the broiler strains were resistant to lincomycin and to the beta-lactams ampicillin and ceftiofur. Less than 10% of the strains were sensitive to the macrolides tylosin and spiramycin, tilmicosin and flumequine. A few strains were sensitive to enrofloxacin and doxycycline. All strains were sensitive to tiamulin.

Use of antimicrobials in veterinary medicine and mechanisms of resistance.

Science.gov (United States)

Schwarz, S; Chaslus-Dancla, E

2001-01-01

This review deals with the application of antimicrobial agents in veterinary medicine and food animal production and the possible consequences arising from the widespread and multipurpose use of antimicrobials. The various mechanisms that bacteria have developed to escape the inhibitory effects of the antimicrobials most frequently used in the veterinary field are reported in detail. Resistance of bacteria to tetracyclines, macrolide-lincosamide-streptogramin antibiotics, beta-lactam antibiotics, aminoglycosides, sulfonamides, trimethoprim, fluoroquinolones and chloramphenicol/florfenicol is described with regard to enzymatic inactivation, decreased intracellular drug accumulation and modification/protection/replacement of the target sites. In addition, basic information is given about mobile genetic elements which carry the respective resistance genes, such as plasmids, transposons, and gene cassettes/integrons, and their ways of spreading via conjugation, mobilisation, transduction, and transformation.

Failure of daptomycin β-Lactam combination therapy to prevent resistance emergence in Enterococcus faecium.

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Menon, Vidthiya; Davis, Rebecca; Shackel, Nick; Espedido, Bjorn A; Beukers, Alicia G; Jensen, Slade O; van Hal, Sebastiaan J

2018-02-01

Daptomycin β-Lactam combination therapy offers "protection" against daptomycin non-susceptibility (DNS) development in Enterococcus faecium. We report failure of this strategy and the importance of source control. Mutations were detected in the LiaF and cls genes in DNS isolates. A single DNS isolate contained an unrecognized mutation, which requires confirmation. Copyright © 2017 Elsevier Inc. All rights reserved.

Analysis of the effect of diabetes type 2 duration on beta cell secretory function and insulin resistance

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Popović Ljiljana

2006-01-01

Full Text Available Diabetes type 2 is a chronic metabolic disorder. Pathogenesis of diabetes type 2 results from the impaired insulin secretion, impaired insulin action and increased endogenous glucose production. Diabetes evolves through several phases characterized by qualitative and quantitative changes of beta cell secretory function. The aim of our study was to analyze the impact of diabetes duration on beta cell secretory function and insulin resistance. The results indicated significant negative correlation of diabetes duration and fasting insulinemia, as well as beta cell secretory function assessed by HOMA β index. Our study also found significant negative correlation of diabetes duration and insulin resistance assessed by HOMA IR index. Significant positive correlation was established between beta cell secretory capacity (fasting insulinemia and HOMA β and insulin resistance assessed by HOMA IR index, independently of diabetes duration. These results indicate that: beta cell secretory capacity, assessed by HOMA β index, significantly decreases with diabetes duration. In parallel with decrease of fasting insulinemia, reduction of insulin resistance assessed by HOMA IR index was found as well.

Biochemical characterization of CTX-M-15 from Enterobacter cloacae and designing a novel non-β-lactam-β-lactamase inhibitor.

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Mohammad Faheem

Full Text Available The worldwide dissemination of CTX-M type β-lactamases is a threat to human health. Previously, we have reported the spread of bla(CTX-M-15 gene in different clinical strains of Enterobacteriaceae from the hospital settings of Aligarh in north India. In view of the varying resistance pattern against cephalosporins and other β-lactam antibiotics, we intended to understand the correlation between MICs and catalytic activity of CTX-M-15. In this study, steady-state kinetic parameters and MICs were determined on E. coli DH5α transformed with bla(CTX-M-15 gene that was cloned from Enterobacter cloacae (EC-15 strain of clinical background. The effect of conventional β-lactamase inhibitors (clavulanic acid, sulbactam and tazobactam on CTX-M-15 was also studied. We have found that tazobactam is the best among these inhibitors against CTX-M-15. The inhibition characteristic of tazobactam is defined by its very low IC(50 value (6 nM, high affinity (K(i = 0.017 µM and better acylation efficiency (k(+2/K' = 0.44 µM(-1s(-1. It forms an acyl-enzyme covalent complex, which is quite stable (k(+3 = 0.0057 s(-1. Since increasing resistance has been reported against conventional β-lactam antibiotic-inhibitor combinations, we aspire to design a non-β-lactam core containing β-lactamase inhibitor. For this, we screened ZINC database and performed molecular docking to identify a potential non-β-lactam based inhibitor (ZINC03787097. The MICs of cephalosporin antibiotics in combination with this inhibitor gave promising results. Steady-state kinetics and molecular docking studies showed that ZINC03787097 is a reversible inhibitor which binds non-covalently to the active site of the enzyme through hydrogen bonds and hydrophobic interactions. Though, it's IC(50 (180 nM is much higher than tazobactam, it has good affinity for CTX-M-15 (K(i = 0.388 µM. This study concludes that ZINC03787097 compound can be used as seed molecule to design more

Covalent docking of selected boron-based serine beta-lactamase inhibitors

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Sgrignani, Jacopo; Novati, Beatrice; Colombo, Giorgio; Grazioso, Giovanni

2015-05-01

AmpC β-lactamase is a hydrolytic enzyme conferring resistance to β-lactam antibiotics in multiple Gram-negative bacteria. Therefore, identification of non-β-lactam compounds able to inhibit the enzyme is crucial for the development of novel antibacterial therapies. In general, AmpC inhibitors have to engage the highly solvent-exposed catalytic site of the enzyme. Therefore, understanding the implications of ligand-protein induced-fit and water-mediated interactions behind the inhibitor-enzyme recognition process is fundamental for undertaking structure-based drug design process. Here, we focus on boronic acids, a promising class of beta-lactamase covalent inhibitors. First, we optimized a docking protocol able to reproduce the experimentally determined binding mode of AmpC inhibitors bearing a boronic group. This goal was pursued (1) performing rigid and flexible docking calculations aiming to establish the role of the side chain conformations; and (2) investigating the role of specific water molecules in shaping the enzyme active site and mediating ligand protein interactions. Our calculations showed that some water molecules, conserved in the majority of the considered X-ray structures, are needed to correctly predict the binding pose of known covalent AmpC inhibitors. On this basis, we formalized our findings in a docking and scoring protocol that could be useful for the structure-based design of new boronic acid AmpC inhibitors.

Dynamics induced by β-lactam antibiotics in the active site of Bacillus subtilis L,D-transpeptidase.

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Lecoq, Lauriane; Bougault, Catherine; Hugonnet, Jean-Emmanuel; Veckerlé, Carole; Pessey, Ombeline; Arthur, Michel; Simorre, Jean-Pierre

2012-05-09

β-lactams inhibit peptidoglycan polymerization by acting as suicide substrates of essential d,d-transpeptidases. Bypass of these enzymes by unrelated l,d-transpeptidases results in β-lactam resistance, although carbapenems remain unexpectedly active. To gain insight into carbapenem specificity of l,d-transpeptidases (Ldts), we solved the nuclear magnetic resonance (NMR) structures of apo and imipenem-acylated Bacillus subtilis Ldt and show that the cysteine nucleophile is present as a neutral imidazole-sulfhydryl pair in the substrate-free enzyme. NMR relaxation dispersion does not reveal any preexisting conformational exchange in the apoenzyme, and change in flexibility is not observed upon noncovalent binding of β-lactams (K(D) > 37.5 mM). In contrast, covalent modification of active cysteine by both carbapenems and 2-nitro-5-thiobenzoate induces backbone flexibility that does not result from disruption of the imidazole-sulfhydryl proton interaction or steric hindrance. The chemical step of the reaction determines enzyme specificity since no differences in drug affinity were observed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Integrin {alpha}{beta}1, {alpha}{sub v}{beta}, {alpha}{sub 6}{beta} effectors p130Cas, Src and talin regulate carcinoma invasion and chemoresistance

Energy Technology Data Exchange (ETDEWEB)

Sansing, Hope A. [Department of Oral and Craniofacial Biology, Louisiana State University Health Sciences Center-New Orleans, School of Dentistry, New Orleans, LA (United States); Sarkeshik, Ali; Yates, John R. [Department of Chemical Physiology, Scripps Research Institute, La Jolla, CA (United States); Patel, Vyomesh; Gutkind, J. Silvio [Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD (United States); Yamada, Kenneth M. [Laboratory of Cell and Developmental Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD (United States); Berrier, Allison L., E-mail: allison.berrier@gmail.com [Department of Oral and Craniofacial Biology, Louisiana State University Health Sciences Center-New Orleans, School of Dentistry, New Orleans, LA (United States)

2011-03-11

Research highlights: {yields} Proteomics of clustered integrin {alpha}{beta}1, {alpha}{sub v}{beta}, {alpha}{sub 6}{beta} receptors in oral carcinoma. {yields} p130Cas, Dek, Src and talin regulate oral carcinoma invasion. {yields} p130Cas, talin, Src and zyxin regulate oral carcinoma resistance to cisplatin. -- Abstract: Ligand engagement by integrins induces receptor clustering and formation of complexes at the integrin cytoplasmic face that controls cell signaling and cytoskeletal dynamics critical for adhesion-dependent processes. This study searches for a subset of integrin effectors that coordinates both tumor cell invasion and resistance to the chemotherapeutic drug cisplatin in oral carcinomas. Candidate integrin effectors were identified in a proteomics screen of proteins recruited to clustered integrin {alpha}{beta}1, {alpha}{sub v}{beta} or {alpha}{sub 6}{beta} receptors in oral carcinomas. Proteins with diverse functions including microtubule and actin binding proteins, and factors involved in trafficking, transcription and translation were identified in oral carcinoma integrin complexes. Knockdown of effectors in the oral carcinoma HN12 cells revealed that p130Cas, Dek, Src and talin were required for invasion through Matrigel. Disruption of talin or p130Cas by RNA interference increased resistance to cisplatin, whereas targeting Dek, Src or zyxin reduced HN12 resistance to cisplatin. Analysis of the spreading of HN12 cells on collagen I and laminin I revealed that a decrease in p130Cas or talin expression inhibited spreading on both matrices. Interestingly, a reduction in zyxin expression enhanced spreading on laminin I and inhibited spreading on collagen I. Reduction of Dek, Src, talin or zyxin expression reduced HN12 proliferation by 30%. Proliferation was not affected by a reduction in p130Cas expression. We conclude that p130Cas, Src and talin function in both oral carcinoma invasion and resistance to cisplatin.

Production of transgenetic sugarbeet (Beta vulgaris L.) plants resistant to phosphinothricin.

Science.gov (United States)

Kishchenko, E M; Komarnitskii, I K; Kuchuk, N V

2005-01-01

A method of Agrobacterium-mediated genetic transformation of sugarbeet (Beta vulgaris L.) with vacuum infiltration has been developed. Aseptic 3-weeks old etiolated seedlings of two diploid O-type sugarbeet lines (KS3 and KS7) have been used for genetic transformation. Transgenic sugarbeet plants carrying the reporter beta-glucuronidase gene have been selected for their resistance to glufosinate ammonium herbicide. Integration of transgenes into sugarbeet genome was confirmed with GUS assay and PCR using primers for bar and gusA genes.

Extended-spectrum beta-lactamase (ESBL)-positive Enterobacteriaceae in municipal sewage and their emission to the environment.

Science.gov (United States)

Korzeniewska, Ewa; Harnisz, Monika

2013-10-15

The spread of Gram-negative bacteria with plasmid-borne extended-spectrum beta-lactamases (ESBLs) has become a worldwide problem. Their prevalence is increasing, both in hospitals and in the environment. The aim of this study was to investigate the presence of ESBL-positive Enterobacteriaceae in municipal sewage and their emission to the ambient air and the river receiving effluent from wastewater treatment plant (WWTP). In the group of 455 isolated strains, up to 19.8% (90 isolates) were phenotypic ESBL-producers. They were detected in the 63 (100%) of sewage samples analyzed, 7 (33.3%) of river water and in 10 (23.8%) of air samples collected at the WWTP area. The plasmid-mediated genes encoding beta-lactams resistance were detected in almost 10% out of bacteria of the WWTP's final effluents and in above 32% out of bacteria of air at the WWTP area. It confirms that those genes are released into the environment, which might facilitate further dissemination among environmental bacteria. Moreover, genes encoding antibiotic resistance were shown to be transferrable to an Escherichia coli recipient strain, which indicates a high possibility of horizontal gene transfer among strains of different genera within the sewage and environmental samples. This study demonstrated that despite the treatment, the municipal sewage may be a reservoir of antibiotic-resistant microorganisms and plasmid-mediated antibiotic resistance genes. This may pose a public health risk, which requires future evaluation and control. Copyright © 2013 Elsevier Ltd. All rights reserved.

Carbapenem-non-susceptible Enterobacteriaceae in Europe : conclusions from a meeting of national experts

NARCIS (Netherlands)

Grundmann, H.; Livermore, D. M.; Giske, C. G.; Canton, R.; Rossolini, G. M.; Campos, J.; Vatopoulos, A.; Gniadkowski, M.; Toth, A.; Pfeifer, Y.; Jarlier, V.; Carmeli, Y.

2010-01-01

The emergence and global spread of carbapenemase-producing Enterobacteriaceae is of great concern to health services worldwide. These bacteria are often resistant to all beta-lactam antibiotics and frequently co-resistant to most other antibiotics, leaving very few treatment options. The

Prevalence and antimicrobial susceptibility of extended-spectrum beta-lactamase producing urinary isolates of Escherichia coli in outpatients

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Marković Tatjana

2013-01-01

Full Text Available Introduction. In Gram-negative bacteria, the production of beta-lactamases is the most important mechanism of resistance to beta-lactam antibiotics. In the Banja Luka region, there were no extensive researches on the prevalence and antimicrobial resistance of the extended-spectrum beta-lactamase (ESBL producing Escherichia coli (E. coli isolates. Objective. The aim of the present study was to determine the presence of ESBL producing E. coli isolates as the cause of the urinary tract infections in outpatients, the distribution of these ESBL isolates according to age and gender of patients and their susceptibility to antimicrobials. Methods. Urine specimens obtained from outpatients were cultured on chromogenic CPS-ID3 media. All plates showing significant (>105 cfu/ml growth of E. coli in pure culture were further processed. Antimicrobial susceptibility testing was performed on VITEK TWO Compact using AST-GN27 cards for testing Gram negative bacteria and detection of ESBL producers. Results. Out of 2,195 isolates, 177 (8.1% were ESBL producers. Ninety-two isolates were obtained from female patients (5% of E. coli isolated from women and 85 isolates from male patients (23% of E. coli isolated from men. High percentage of ESBL isolates was detected in the infant age group under one year (36.7% and in the age group over 60 years (28.8%. All ESBL isolates were susceptible to imipenem and resistant to ampicillin, piperacillin, cefazolin, cefotaxime, ceftazidime and cefepime. There was a significant resistance to amikacin (79.1%, gentamicin (76.8%, amoxicillin/clavulanate (54.8% and trimethoprim/sulphamethoxazole (45.8%. Resistance to nutrofurantoin was 13.6%. Conclusion. This study has demonstrated the presence of ESBL producing E. coli urinary isolates in outpatients, and their extensive susceptibility to imipenem and nitrofurantoin.

Transition Metal-Free Selective Double sp(3) C-H Oxidation of Cyclic Amines to 3-Alkoxyamine Lactams.

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Osorio-Nieto, Urbano; Chamorro-Arenas, Delfino; Quintero, Leticia; Höpfl, Herbert; Sartillo-Piscil, Fernando

2016-09-16

The first chemical method for selective dual sp(3) C-H functionalization at the alpha-and beta positions of cyclic amines to their corresponding 3-alkoxyamine lactams is reported. Unlike traditional Cα-H oxidation of amines to amides mediated by transition metals, the present protocol, which involves the use of NaClO2/TEMPO/NaClO in either aqueous or organic solvent, not only allows the Cα-H oxidation but also the subsequent functionalization of the unreactive β-methylene group in an unprecedented tandem fashion and using environmentally friendly reactants.

Diversity of fecal coliforms and their antimicrobial resistance patterns in wastewater treatment model plant.

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Luczkiewicz, A; Fudala-Ksiazek, S; Jankowska, K; Quant, B; Olańczuk-Neyman, K

2010-01-01

The occurrence of resistance patterns among wastewater fecal coliforms was determined in the study. Susceptibility of the isolates was tested against 19 antimicrobial agents: aminoglycosides, aztreonam, carbapenems, cephalosporines, beta-lactam/beta-lactamase inhibitors, penicillines, tetracycline, trimethoprim/sulfamethoxazole, and fluoroquinolones. Additionally the removal of resistant isolates was evaluated in the laboratory-scale wastewater treatment model plant (M-WWTP), continuously supplied with the wastewater obtained from the full-scale WWTP. Number of fecal coliforms in raw (after mechanical treatment) and treated wastewater, as well as in aerobic chamber effluent was determined using selective medium. The selected strains were identified and examined for antibiotic resistance using Phoenix Automated Microbiology System (BD Biosciences, USA). The strains were identified as Escherichia coli (n=222), Klebsiella pneumoniae ssp. ozaenae (n=9), and Pantoea agglomerans (n=1). The isolate of P. agglomerans as well as 48% of E. coli isolates were sensitive to all antimicrobials tested. The most frequent resistance patterns were found for ampicillin: 100% of K. pneumoniae ssp. ozaenae and 41% of E. coli isolates. Among E. coli isolates 12% was regarded as multiple antimicrobial resistant (MAR). In the studied M-WWTP, the applied activated sludge processes reduced considerably the number of fecal coliforms, but increased the ratio of antimicrobial-resistant E. coli isolates to sensitive ones, especially among strains with MAR patterns.

Oat beta-glucan ameliorates insulin resistance in mice fed on high-fat and high-fructose diet

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Jie Zheng

2013-12-01

Full Text Available Methods: This study sought to evaluate the impact of oat beta-glucan on insulin resistance in mice fed on high-fat and high-fructose diet with fructose (10%, w/v added in drinking water for 10 weeks. Results: The results showed that supplementation with oat beta-glucan could significantly reduce the insulin resistance both in low-dose (200 mg/kg−1 body weight and high-dose (500 mg/kg−1 body weight groups, but the high-dose group showed a more significant improvement in insulin resistance (P<0.01 compared with model control (MC group along with significant improvement in hepatic glycogen level, oral glucose, and insulin tolerance. Moreover, hepatic glucokinase activity was markedly enhanced both in low-dose and high-dose groups compared with that of MC group (P<0.05. Conclusion: These results suggested that supplementation of oat beta-glucan alleviated insulin resistance and the effect was dose dependent.

Are Sewage Treatment Plants Promoting Antibiotic Resistance?

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1. Introduction 1.1. How bacteria exhibit resistance 1.1.1. Resistance to -lactams 1.1.2. Resistance to sulphonamides and trimethoprim 1.1.3. Resistance to macrolides 1.1.4. Resistance to fluoroquinolones 1.1.5. Resistance to tetracyclines 1.1.6. Resistance to nitroimidaz...

Targeted simplification versus antipseudomonal broad-spectrum beta-lactams in patients with bloodstream infections due to Enterobacteriaceae (SIMPLIFY): a study protocol for a multicentre, open-label, phase III randomised, controlled, non-inferiority clinical trial.

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López-Cortés, Luis Eduardo; Rosso-Fernández, Clara; Núñez-Núñez, María; Lavín-Alconero, Lucía; Bravo-Ferrer, José; Barriga, Ángel; Delgado, Mercedes; Lupión, Carmen; Retamar, Pilar; Rodríguez-Baño, Jesús

2017-06-09

Within the context of antimicrobial stewardship programmes, de-escalation of antimicrobial therapy is one of the proposed strategies for reducing the unnecessary use of broad-spectrum antibiotics (BSA). The empirical treatment of nosocomial and some healthcare-associated bloodstream infections (BSI) frequently includes a beta-lactam with antipseudomonal activity as monotherapy or in combination with other drugs, so there is a great opportunity to optimise the empirical therapy based on microbiological data. De-escalation is assumed as standard of care for experts in infectious diseases. However, it is less frequent than it would desirable. The SIMPLIFY trial is a multicentre, open-label, non-inferiority phase III randomised controlled clinical trial, designed as a pragmatic 'real-practice' trial. The aim of this trial is to demonstrate the non-inferiority of de-escalation from an empirical beta-lactam with antipseudomonal activity to a targeted narrow-spectrum antimicrobial in patients with BSI due to Enterobacteriaceae . The primary outcome is clinical cure, which will be assessed at the test of cure visit. It will be conducted at 19 Spanish public and university hospitals. Each participating centre has obtained the approval of the ethics review committee, the agreement of the directors of the institutions and authorisation from the Spanish Regulatory Agency (Agencia Española del Medicamento y Productos Sanitarios). Data will be presented at international conferences and published in peer-reviewed journals. Strategies to reduce the use of BSA should be a priority. Most of the studies that support de-escalation are observational, retrospective and heterogeneous. A recent Cochrane review stated that well-designed clinical trials should be conducted to assess the safety and efficacy of de-escalation. The European Union Clinical Trials Register: EudraCT number 2015-004219-19. Clinical trials.gov: NCT02795949. Protocol version: V.2.0, dated 16 May 2016. All items from

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

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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...

Frecuencia de enzimas asociadas a sensibilidad disminuida a betalactámicos en aislados de enterobacterias, Caracas, Venezuela Frequency of enzymes associated with reduced sensitivity to beta-lactam antibiotics in enterobacteria isolates, Caracas, Venezuela

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Daniel Marcano

2011-12-01

ón adecuada de los perfiles de sensibilidad y la confirmación molecular del mecanismo presente.OBJECTIVE: To determine the frequency of enzymatic mechanisms associated with reduced sensitivity to broad-spectrum beta-lactam antibiotics in enterobacteria isolates obtained at hospital centers in Caracas, Venezuela. METHODS: A cross-sectional study was conducted on enterobacteria isolated from patients at eight hospital centers in Caracas, Venezuela, from 15 October 2009 to 15 January 2010. The species were identified using conventional biochemical tests, and their susceptibility to antimicrobial drugs was assessed by antibiogram (Kirby-Bauer method, using the 2010 performance standards published by the Clinical and Laboratory Standards Institute. Beta-lactam-resistant genes were detected using an enhanced polymerase chain reaction assay. RESULTS: Of 1 235 isolates, 207 (16.8% exhibited resistance to third- and fourth-generation cephalosporins, carbapenems, or both. They presented the following phenotypes: extended-spectrum beta-lactamase (ESBL, 93.8%; depressed AmpC, 4.3%; and carbapenemase, 1.9%. Further characterization of the first two phenotypes yielded the following breakdown of types: SHV, 36.7%; CTX-M-1 group, 22.3%; TEM, 21.7%; CTX-M-1 group with impermeability, 5.2%; two-enzyme combinations, 4.5%; CTX-M-2 group, 4.3%; PER, 3.4%; and KPC, 1.9%. The SHV type was predominant in the public hospital strains, whereas the CTX-M-1 group was most common in the strains from the private hospitals. CONCLUSIONS: Of the enzymatic mechanisms investigated, the SHV type was the most frequent, followed by the CTX-M-1 group and the TEM type. Also, a high percentage of type KPC was found. The research reported here is one of only a few multicenter studies that have been conducted in Venezuela to evaluate the frequency of this type of antimicrobial resistance mechanism, including phenotypical and molecular charac-terization. It was shown that the detection methods require proper

Prevalence and characteristics of methicillin-resistant coagulase-negative staphylococci from livestock, chicken carcasses, bulk tank milk, minced meat, and contact persons

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Zweifel Claudio

2011-01-01

Full Text Available Abstract Background Methicillin-resistant coagulase-negative staphylococci (MR-CNS are of increasing importance to animal and public health. In veterinary medicine and along the meat and milk production line, only limited data were so far available on MR-CNS characteristics. The aim of the present study was to evaluate the prevalence of MR-CNS, to identify the detected staphylococci to species level, and to assess the antibiotic resistance profiles of isolated MR-CNS strains. Results After two-step enrichment and growth on chromogenic agar, MR-CNS were detected in 48.2% of samples from livestock and chicken carcasses, 46.4% of samples from bulk tank milk and minced meat, and 49.3% of human samples. Using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS, 414 selected MR-CNS strains belonged to seven different species (S. sciuri, 32.6%; S. fleurettii, 25.1%; S. haemolyticus, 17.4%; S. epidermidis, 14.5%, S. lentus, 9.2%; S. warneri, 0.7%; S. cohnii, 0.5%. S. sciuri and S. fleurettii thereby predominated in livestock, BTM and minced meat samples, whereas S. epidermidis and S. haemolyticus predominated in human samples. In addition to beta-lactam resistance, 33-49% of all 414 strains were resistant to certain non-beta-lactam antibiotics (ciproflaxacin, clindamycin, erythromycin, tetracycline. Conclusions A high prevalence of MR-CNS was found in livestock production. This is of concern in view of potential spread of mecA to S. aureus (MRSA. Multiresistant CNS strains might become an emerging problem for veterinary medicine. For species identification of MR-CNS isolated from different origins, MALDI-TOF MS proved to be a fast and reliable tool and is suitable for screening of large sample amounts.

Amoxicillin / Clavulanic Acid and Cefotaxime Resistance in Salmonella Minnesota and Salmonella Heidelberg from Broiler Chickens

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Rodrigues IBBE

2017-10-01

Full Text Available This study investigated the resistance of various Salmonella strains to beta-lactam antibiotics. Salmonella Minnesota (36 strains and Salmonella Heidelberg (24 strains were isolated from broiler chickens and carcasses by the Disk Diffusion Test and resistance genes blaCTX-M-8, blaACC-1 and blaCMY-2 were detected by PCR. Of the 60 strains tested, 80% were resistant to at least one antibiotic. Specifically, 66.7% were resistant to amoxicillin/clavulanic acid and 75% were resistant to cefotaxime. Among the amoxicillin/clavulanic acid resistant strains, the blaCMY-2 gene was detected in 40%, blaACC-1 in 37.5% and blaCTX-M-8 in 7.5%. Among the cefotaxime resistant strains, we detected the genes blaCTX-M-8 in 13.3%, blaACC-1 in 33.3%, and blaCMY-2 in 31.1%. The presence of cefotaxime- and amoxicillin/clavulanic acid-resistant Salmonella in poultry, and the prevalence of extended spectrum betalactamases and AmpC-betalactamases in these strains are of huge concern to public health and economy.

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.

Screening of antibiotic susceptibility to β-lactam-induced elongation of Gram-negative bacteria based on dielectrophoresis.

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Chung, Cheng-Che; Cheng, I-Fang; Chen, Hung-Mo; Kan, Heng-Chuan; Yang, Wen-Horng; Chang, Hsien-Chang

2012-04-03

We demonstrate a rapid antibiotic susceptibility test (AST) based on the changes in dielectrophoretic (DEP) behaviors related to the β-lactam-induced elongation of Gram-negative bacteria (GNB) on a quadruple electrode array (QEA). The minimum inhibitory concentration (MIC) can be determined within 2 h by observing the changes in the positive-DEP frequency (pdf) and cell length of GNB under the cefazolin (CEZ) treatment. Escherichia coli and Klebsiella pneumoniae and the CEZ are used as the sample bacteria and antibiotic respectively. The bacteria became filamentous due to the inhibition of cell wall synthesis and cell division and cell lysis occurred for the higher antibiotic dose. According to the results, the pdfs of wild type bacteria decrease to hundreds of kHz and the cell length is more than 10 μm when the bacterial growth is inhibited by the CEZ treatment. In addition, the growth of wild type bacteria and drug resistant bacteria differ significantly. There is an obvious decrease in the number of wild type bacteria but not in the number of drug resistant bacteria. Thus, the drug resistance of GNB to β-lactam antibiotics can be rapidly assessed. Furthermore, the MIC determined using dielectrophoresis-based AST (d-AST) was consistent with the results of the broth dilution method. Utilizing this approach could reduce the time needed for bacteria growth from days to hours, help physicians to administer appropriate antibiotic dosages, and reduce the possibility of the occurrence of multidrug resistant (MDR) bacteria.

Susceptibility of Eikenella corrodens to Newer Beta-Lactam Antibiotics

OpenAIRE

1981-01-01

In vitro susceptibility testing of 28 strains of Eikenella corrodens by the agar dilution technique showed that all strains were uniformly susceptible to penicillin, ticarcillin, cefoxitin, cefotaxime, N-formimidoyl thienamycin, and moxalactam and resistant to clindamycin and cefadroxil. Cefoperazone, piperacillin, and mezlocillin showed good activity, with some strains relatively resistant. Bacampicillin and cefamandole showed relatively poor activity.

Marinopyrrole Derivatives as Potential Antibiotic Agents against Methicillin-Resistant Staphylococcus aureus (II

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Rongshi Li

2013-08-01

Full Text Available Methicillin-resistant Staphylococcus aureus (MRSA continues to be a major problem, causing severe and intractable infections worldwide. MRSA is resistant to all beta-lactam antibiotics, and alternative treatments are limited. A very limited number of new antibiotics have been discovered over the last half-century, novel agents for the treatment of MRSA infections are urgently needed. Marinopyrrole A was reported to show antibiotic activity against MRSA in 2008. After we reported the first total synthesis of (±-marinopyrrole A, we designed and synthesized a series of marinopyrrole derivatives. Our structure activity relationship (SAR studies of these novel derivatives against a panel of Gram-positive pathogens in antibacterial assays have revealed that a para-trifluoromethyl analog (33 of marinopyrrole A is ≥63-, 8-, and 4-fold more potent than vancomycin against methicillin-resistant Staphylococcus epidermidis (MRSE, methicillin-susceptible Staphylococcus aureus (MSSA and MRSA, respectively. The results provide valuable information in the search for new-generation antibiotics.

[Associations of insulin resistance and pancreatic beta-cell function with plasma glucose level in type 2 diabetes].

Science.gov (United States)

Nian, Xiaoping; Sun, Gaisheng; Dou, Chunmei; Hou, Hongbo; Fan, Xiuping; Yu, Hongmei; Ma, Ling; He, Bingxian

2002-06-10

To investigate the influence of insulin resistance and pancreatic beta-cell function on plasma glucose level in type 2 diabetes so as to provide theoretical basis for reasonable selection of hypoglycemic agents. The plasma non-specific insulin (NSINS), true insulin (TI) and glucose in eight-one type 2 diabetics, 38 males and 43 females, with a mean age of 53 years, were examined 0, 30, 60 and 120 minutes after they had 75 grams of instant noodles. The patients were divided into two groups according to their fasting plasma glucose (FPG): group A (FPG = 8.89 mmol/L). The insulin resistance was evaluated by HOMA-IR, the beta-cell function was evaluated by HOMA-beta formula and the formula deltaI(30)/deltaG(30) = (deltaI(30)-deltaI(0))/(deltaG(30)-deltaG(0)). The insulin area under curve (INSAUC) was evaluated by the formula INSAUC=FINS/2+INS(30)+INS(60)+INS(120)/2. The mean FPG was 6.23 mmol/L in group A and 12.6 mmol/L in group B. PG2H was 11.7 mmol/L in group A and 19.2 mmol/L in group B. The TI levels in group B at 0, 30, 60, 120 min during standard meal test were significantly higher than those in group A: 6.15 +/- 1.06 vs 4.77 +/- 1.06, 9.76 +/- 1.1 vs 5.88 +/- 1.1,14.68 +/- 1.11 vs 6.87 +/- 1.1 and 17.13 +/- 1.12 vs 8.0 +/- 1.1 microU/dl (all P< 0.01). The NSINS showed the same trend. The insulin resistance in group B was 1.5 times that in group A. With the insulin resistance adjusted, the beta cell function in group A was 5 to 6 times that in group B. The INSAUC in group A was 1.66 times larger than that in group B, especially the INSAUC for true insulin (2 times larger). The contribution of insulin resistance and beta cell function to PG2H was half by half in group A and 1:8 in group B. beta cell function calculated by insulin (Homa-beta) explained 41% of the plasma glucose changes in group A and 54% of the plasma glucose changes in group B. The contribution of insulin deficiency to plasma glocose was 3.3.times that of insulin resistance in group A and was 9

Extended spectrum beta lactamase (ESBL) producing bacteria urinary tract infections and complex pediatric urology.

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Wragg, Ruth; Harris, Anna; Patel, Mitul; Robb, Andrew; Chandran, Harish; McCarthy, Liam

2017-02-01

Extended spectrum beta lactamase (ESBL) producing bacteria are resistant to most beta-lactam antibiotics including third-generation cephalosporins, quinolones and aminoglycosides. This resistance is plasmid-borne and can spread between species. Management of ESBL is challenging in children with recurrent urinary tract infections (UTIs) and complex urological abnormalities. We aim to quantify the risk in children and specifically in urological patients. Retrospective review of a microbiology database (April 2014 to November 2015). This identified urine isolates, pyuria, ESBL growth and patient demographics. Data analysis was by Chi square, Mann-Whitney U-test and ANOVA. A P value of 10×10 6 WC/L). 136 urine cultures (n=79 patients) grew purely ESBL. Overall, 5.2% of urine isolates were ESBL and 9.5% isolates with pyuria (>100×10 6 WC/L) had ESBL, whereas only 22/1032 (2.1%) with no pyuria, (Pantibiotics). Over the study period, there was no significant rise of the monthly incidence between 2014 and 2015 (ANOVA P=0.1). This study is the first to document the incidence of ESBL in children (5%), and estimate the frequency of possible plasmid transmission between bacterial species in children. This quantifies the risk of ESBL, especially to urology patients, and mandates better antibiotic stewardship. Level IIc. Copyright © 2017. Published by Elsevier Inc.

Type 1 Ig-E mediated allergy to human insulin, insulin analogues and beta-lactam antibiotics Hipersensibilidade imediata a insulina humana, análogos de insulina e a antibióticos beta-lactâmicos

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Pedro Andrade

2012-12-01

Full Text Available Insulin, a crucial therapeutic agent for diabetes mellitus, has been rarely associated with hypersensitivity events. We present a 69-year-old type-2 diabetic patient with urticariform lesions on the sites of subcutaneous injection of insulin. The patient denied any known allergies, except for an unspecific cutaneous reaction after intramuscular penicillin administration in childhood. Prick tests revealed positive reactions to all tested human insulins and insulin analogues. Serum IgE levels were above normal range and RAST tests were positive for human, bovine and porcine insulins, as well as beta-lactams. Type 1 IgEmediated allergy to insulin analogues demands a prompt diagnosis and represents a significant therapeutic challenge in diabetic patients.A insulina é um agente indispensável para o controlo da diabetes mellitus. Os efeitos adversos da sua administração, em particular fenómenos de hipersensibilidade, são raros. Apresentamos um doente de 69 anos, diabético do tipo 2, com episódios recorrentes de lesões urticariformes nos locais de administração subcutânea de insulina. Negava alergias medicamentosas, à excepção de reacção não especificada na infância após penicilina intramuscular. Foram realizados testes cutâneos por puntura (prick tests com diversos tipos de insulina humana e análogos, todos com reacções positivas, associando elevação dos níveis de IgE sérica e provas RAST positivas para as insulinas humana, bovina e porcina e para os antibióticos beta-lactâmicos. A alergia a análogos de insulina exige um diagnóstico precoce, originando um desafio terapêutico importante no doente diabético.

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.

Gold-catalyzed heterocyclizations in alkynyl- and allenyl-β-lactams

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Pedro Almendros

2011-05-01

Full Text Available New gold-catalyzed methods using the β-lactam scaffold have been recently developed for the synthesis of different sized heterocycles. This overview focuses on heterocyclization reactions of allenic and alkynic β-lactams which rely on the activation of the allene and alkyne component. The mechanism as well as the regio- and stereoselectivity of the cyclizations are also discussed.

Antibiotic resistance genes in anaerobic bacteria isolated from primary dental root canal infections.

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Rôças, Isabela N; Siqueira, José F

2012-12-01

Fourty-one bacterial strains isolated from infected dental root canals and identified by 16S rRNA gene sequence were screened for the presence of 14 genes encoding resistance to beta-lactams, tetracycline and macrolides. Thirteen isolates (32%) were positive for at least one of the target antibiotic resistance genes. These strains carrying at least one antibiotic resistance gene belonged to 11 of the 26 (42%) infected root canals sampled. Two of these positive cases had two strains carrying resistance genes. Six out of 7 Fusobacterium strains harbored at least one of the target resistance genes. One Dialister invisus strain was positive for 3 resistance genes, and 4 other strains carried two of the target genes. Of the 6 antibiotic resistance genes detected in root canal strains, the most prevalent were blaTEM (17% of the strains), tetW (10%), and ermC (10%). Some as-yet-uncharacterized Fusobacterium and Prevotella isolates were positive for blaTEM, cfxA and tetM. Findings demonstrated that an unexpectedly large proportion of dental root canal isolates, including as-yet-uncharacterized strains previously regarded as uncultivated phylotypes, can carry antibiotic resistance genes. Copyright © 2012 Elsevier Ltd. All rights reserved.

Molecular determination of extended spectrum b-lactamases antibiotics resistance genes in E.coli isolated from diarrhea in cattle

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Ghassan Khudhair Ismaeel

2017-07-01

Full Text Available None response to the treatment by an antibiotic called antibiotics resistance result from some genes called resistance genes .This mechanism is widespread in most of the bacteria, like E.coli . All of the extended resistance genes called (ESBIS is a typical example for study of some genes that resistance beta-lactam antibiotic is subject of this research. Fifty feces sample were collected from cattle suffering from diarrhea in alqaissiyah city were cultured on selective media for E.coli , then DNA was extracted from all E.coli isolates for antibiotic resistance gene detection by PCR ; The results of this study revealed the prevalence of B-lactamase gene four B-lactamases genes in E.coli blaAmpc gene were (91.4%, the blactx-m gene were (80%, blaTem were (62.8% and finally and blaSHV gene were (22% among isolates E.coli ; blaAMPC gene has high prevalence than others genes while blaSHV was a lower percentage than other genes

A novel chimeric peptide with antimicrobial activity.

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Alaybeyoglu, Begum; Akbulut, Berna Sariyar; Ozkirimli, Elif

2015-04-01

Beta-lactamase-mediated bacterial drug resistance exacerbates the prognosis of infectious diseases, which are sometimes treated with co-administration of beta-lactam type antibiotics and beta-lactamase inhibitors. Antimicrobial peptides are promising broad-spectrum alternatives to conventional antibiotics in this era of evolving bacterial resistance. Peptides based on the Ala46-Tyr51 beta-hairpin loop of beta-lactamase inhibitory protein (BLIP) have been previously shown to inhibit beta-lactamase. Here, our goal was to modify this peptide for improved beta-lactamase inhibition and cellular uptake. Motivated by the cell-penetrating pVEC sequence, which includes a hydrophobic stretch at its N-terminus, our approach involved the addition of LLIIL residues to the inhibitory peptide N-terminus to facilitate uptake. Activity measurements of the peptide based on the 45-53 loop of BLIP for enhanced inhibition verified that the peptide was a competitive beta-lactamase inhibitor with a K(i) value of 58 μM. Incubation of beta-lactam-resistant cells with peptide decreased the number of viable cells, while it had no effect on beta-lactamase-free cells, indicating that this peptide had antimicrobial activity via beta-lactamase inhibition. To elucidate the molecular mechanism by which this peptide moves across the membrane, steered molecular dynamics simulations were carried out. We propose that addition of hydrophobic residues to the N-terminus of the peptide affords a promising strategy in the design of novel antimicrobial peptides not only against beta-lactamase but also for other intracellular targets. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.

Effect of iron on pancreatic beta cell function and insulin resistance ...

African Journals Online (AJOL)

Background: Increase in total body iron store has been reported in the aetiology and development of diabetes mellitus. The effect of iron supplementation in female with respect to the incidence of diabetes mellitus was investigated on the pancreatic beta cell function and insulin resistance in normal female rats. Methods: ...

Investigation of the sensitising and cross-sensitising potential of textile dyes and beta-lactam antibiotics using a biphasic mice local lymph node assay.

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Ahuja, Varun; Schreiber, Clemens; Platzek, Thomas; Stahlmann, Ralf

2009-07-01

We used a modified protocol of the murine local lymph node assay (LLNA) to study the cross-sensitising potential of (a) textile dye disperse yellow 3 and its metabolite 2-amino-p-cresol, (b) two antibiotics, penicillin G and cefotiam. The test substances were applied in a biphasic manner, i.e. first on the shaved skin of the back followed by application on the dorsal side of the ears after 2 weeks. The end-points analysed included thickness and weight of an ear-biopsy, weight and cell number of the draining lymph node, and lymphocyte cell surface markers analysed by flow-cytometry. Disperse yellow 3 and its metabolite significantly altered the various end-points at both the tested concentrations (0.5 and 1%), thus demonstrating the sensitising potential of the two substances. The cross-sensitisation study showed significant modulation in the tested variables in the treated group as compared to the control, signifying cross-sensitisation potential of the two substances. Penicillin G and cefotiam showed significant changes in various end-points, pointing towards their sensitising potential. However, even at 50% concentration of the beta-lactams no significant change in any end-point indicating absence of cross-reactivity of the antibiotics was noticed. We conclude that a biphasic, modified protocol of the LLNA is a suitable approach to test for a cross-reactivity potential of two related compounds.

SHV-type extended-spectrum beta-lactamase (ESBL are encoded in related plasmids from enterobacteria clinical isolates from Mexico beta-Lactamasas de espectro extendido (BLEE tipo SHV están codificadas en plásmidos relacionados en aislamientos clínicos de enterobacterias en México

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Ulises Garza-Ramos

2007-12-01

Full Text Available OBJECTIVE: In this work we report the molecular characterization of beta-lactam antibiotics resistance conferred by genes contained in plasmids from enterobacteria producing extended-spectrum beta-lactamases (ESBL. MATERIAL AND METHODS: Fourteen enterobacterial clinical isolates selected from a group of strains obtained from seven different hospitals in Mexico during 1990-1992 and 1996-1998 were analyzed at the Bacterial Resistance Laboratory (National Institute Public Health, Cuernavaca. Molecular characterization included PFGE, IEF of beta-lactamases, bacterial conjugation, PCR amplification and DNA sequencing, plasmid extraction and restriction. RESULTS: Isolates were genetically unrelated. ESBL identified were SHV-2 (5/14 and SHV-5 (9/14 type. Cephalosporin-resistance was transferable in 9 of 14 (64% clinical isolates with only one conjugative plasmid, DNA finger printing showed a similar band pattern in plasmids. CONCLUSIONS: The dissemination of cephalosporin resistance was due to related plasmids carrying the ESBL genes.OBJETIVO: En este trabajo se reporta la caracterización molecular de la resistencia a antibiótico beta-lactámicos conferida por genes contenidos en plásmidos de enterobacterias productoras de beta-lactamasas de espectro extendido (BLEEs. MATERIAL Y MÉTODOS: Catorce aislamientos clínicos de enterobacterias fueron seleccionados por conveniencia de un banco de cepas obtenidas de siete diferentes hospitales de México durante los periodos 1990-1992 y 1996-1998 y fueron procesados en el Laboratorio de Resistencia Bacteriana (Instituto Nacional de Salud Pública, Cuernavaca. En la caracterización se empleó PFGE, IEF para beta-lactamasas, conjugación bacteriana, amplificación por PCR y secuenciación de DNA, extracción y restricción de plásmidos. RESULTADOS: Las 14 cepas fueron no relacionadas genéticamente. Se identificaron BLEEs tipo SHV-2 (5/14 y SHV-5 (9/14. La resistencia a cefalosporinas fue transferida por

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

Abundances of tetracycline, sulphonamide and beta-lactam antibiotic resistance genes in conventional wastewater treatment plants (WWTPs) with different waste load

DEFF Research Database (Denmark)

Laht, Mailis; Karkman, Antti; Voolaid, Veiko

2014-01-01

Antibiotics and antibiotic resistant bacteria enter wastewater treatment plants (WWTPs), an environment where resistance genes can potentially spread and exchange between microbes. Several antibiotic resistance genes (ARGs) were quantified using qPCR in three WWTPs of decreasing capacity located...... abundances with 16S rRNA gene abundances while assessing if the respective genes increased or decreased during treatment. ARGs were detected in most samples; sul1, sul2, and tetM were detected in all samples. Statistically significant differences (adjusted p... in the relative abundance of resistance genes, while the raw abundances fell by several orders of magnitude. Standard water quality variables (biological oxygen demand, total phosphorus and nitrogen, etc.) were weakly related or unrelated to the relative abundance of resistance genes. Based on our results we...

Old Drugs To Treat Resistant Bugs: Methicillin-Resistant Staphylococcus aureus Isolates with mecC Are Susceptible to a Combination of Penicillin and Clavulanic Acid.

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Ba, Xiaoliang; Harrison, Ewan M; Lovering, Andrew L; Gleadall, Nicholas; Zadoks, Ruth; Parkhill, Julian; Peacock, Sharon J; Holden, Matthew T G; Paterson, Gavin K; Holmes, Mark A

2015-12-01

β-Lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA) is mediated by the expression of an alternative penicillin-binding protein 2a (PBP2a) (encoded by mecA) with a low affinity for β-lactam antibiotics. Recently, a novel variant of mecA, known as mecC, was identified in MRSA isolates from both humans and animals. In this study, we demonstrate that mecC-encoded PBP2c does not mediate resistance to penicillin. Rather, broad-spectrum β-lactam resistance in MRSA strains carrying mecC (mecC-MRSA strains) is mediated by a combination of both PBP2c and the distinct β-lactamase encoded by the blaZ gene of strain LGA251 (blaZLGA251), which is part of mecC-encoding staphylococcal cassette chromosome mec (SCCmec) type XI. We further demonstrate that mecC-MRSA strains are susceptible to the combination of penicillin and the β-lactam inhibitor clavulanic acid in vitro and that the same combination is effective in vivo for the treatment of experimental mecC-MRSA infection in wax moth larvae. Thus, we demonstrate how the distinct biological differences between mecA- and mecC-encoded PBP2a and PBP2c have the potential to be exploited as a novel approach for the treatment of mecC-MRSA infections. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Occurrence of transferable antibiotic resistances in commercialized ready-to-eat mealworms (Tenebrio molitor L.).

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Osimani, Andrea; Cardinali, Federica; Aquilanti, Lucia; Garofalo, Cristiana; Roncolini, Andrea; Milanović, Vesna; Pasquini, Marina; Tavoletti, Stefano; Clementi, Francesca

2017-12-18

The present study aimed to assess the occurrence of transferable determinants conferring resistance to tetracyclines, macrolide-lincosamide-streptogramin B, vancomycin, beta-lactams, and aminoglycosides in 40 samples of commercialized edible mealworms (Tenebrio molitor L.) purchased from European Union (EU) and non-EU producers. A high prevalence of tet(K) was observed in all of the samples assayed, with percentages of PCR-based positivity that ranged from 80% (samples from Thailand) to 100% (samples from the Netherlands, Belgium and France). For macrolides, erm(B) prevailed, being detected in 57.5% of the samples assayed, whereas erm(A) and erm(C) were detected with lower frequencies. Genes for resistance to vancomycin were only detected in samples produced in France and Belgium, with 90% and 10% of the samples being positive for vanA, respectively. Beta-lactamase genes were found with low occurrence, whereas the gene aac-aph, conferring high resistance to aminoglycosides, was found in 40% of the samples produced in the Netherlands and Belgium and 20% of the samples produced in Thailand. The results of Principal Coordinate Analysis and Principal Component Analysis depicted a clean separation of the samples collected from the four producers based on the distribution of the 12 AR determinants considered. Given the growing interest on the use of mealworms as a novel protein source, AR detection frequencies found in the present study suggest further investigation into the use of antibiotics during rearing of this insect species and more extensive studies focused on the factors that can affect the diffusion of transferable ARs in the production chain. Until such studies are completed, prudent use of antibiotics during rearing of edible insects is recommended. Copyright © 2017 Elsevier B.V. All rights reserved.

Structural comparison of 1{beta}-Methylcarbapenem, Carbapenem and Penem: NMR studies and theoretical calculations

Energy Technology Data Exchange (ETDEWEB)

Sunagawa, M.; Sasaki, A.; Igarashi, J.-E.; Nishimura, T. [Research Center, Sumitomo Pharmaceuticals Co., Ltd., 3-1-98 Kasugadenaka, Konohanaku, Osaka (Japan)

1998-04-01

Structural comparisons of meropenem (1), desmethyl meropenem (2) and the penem analogue (3) which contain the same side chains at both C-2 and C-6 were performed using {sup 1}H NMR measurements together with 3-21G* level of ab initio MO and molecular mechanics calculations. The ab initio MO calculations reproduced the skeletons of these strained {beta}-lactam rings in good agreement with the crystallographic data. {sup 1}H NMR measurements in aqueous solution together with molecular modeling studies indicated that there were conformational differences of the C-2 and C-6 side chains in this series of compounds. These observations suggested that the conformational differences could affect their biological activities. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

Prevalence of AmpC type extended spectrum beta lactamases genes in clinical Samples of E.coli Isolated from Poultry and Humans

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Elham Farrokhnazar

2016-07-01

Full Text Available Emergence of antibiotic resistance among pathogens, particularly in health centers and hospitals, has become a major public health problem. This study identified AmpC-type beta-lactamase against the antibiotic ceftazidime, cefotaxime and cefpodoxime in E.coli isolated from human and poultry and types of producing genes were studied by PCR. In this study, 500 clinical human samples of urine from hospitals of Tehran during 5 months as well as 300 poultry samples were collected and transferred to the microbiology laboratory. Biochemical tests such as TSI, Urea and IMViC were performed on suspected colonies with E.coli. To identify ESBL producing strains, beta-lactamase samples were cultured on Mueller-Hinton agar through antimicrobial susceptibility test by disk agar diffusion based on the standard CLSI for initial screening. PCR reactions were done using specific primers CITM, EBCM, DHAM and MOXM to identify the beta-lactamase AmpC. A number of 200 human and 55 poultry E.coli samples were screened. In human samples, 105 (52.5% were resistant and potential producers of ESBL and AmpC; out of those, 102 (51% produced ESBL and 3 (1.5% potentially produced AmpC. In the study on 55 E.coli isolates from poultry samples based on the results of disk agar diffusion test, 4 (7.2% samples were resistant and potential producers of ESBL. None of the samples were AmpC producers. Through PCR, 2 human samples (1% were CITM positive and one sample (0.5% was DHAM positive. Through the PCR carried out on poultry samples, there were no bands with 4 primers. There was AmpC in human samples; while further studies are required for poultry samples, because poultry significantly contribute in production of food for humans and can be an important source for dissemination of antibiotic resistance. Given the significance of Ampc in providing high levels of beta-lactam antibiotic resistance, particularly third generation cephalosporins which are very common treatments, more

Dietary beta-1,3 glucan potentiates innate immunity and disease resistance of Asian catfish, Clarias batrachus (L.).

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Kumari, J; Sahoo, P K

2006-02-01

This study investigated the effects of short and prolonged administration of a yeast beta-glucan on non-specific immune parameters, growth rate and the disease resistance of Asian catfish, Clarias batrachus. Fish fed with a basal diet (control) and test diet (basal diet supplemented with 0.1% glucan) for 1, 2 and 3 weeks were assayed for superoxide production, serum myeloperoxidase (MPO) content, natural haemagglutinin level, complement and lysozyme activities. Fish were weighed at weekly intervals and specific growth rate (SGR, % increase in body weight per day) was determined. After each week, fish were challenged with Aeromonas hydrophila to measure the level of protection. Results showed that glucan administration at 0.1% in feed, significantly (Pcomplement activity and SGR were not affected by the dietary supplementation of yeast glucan. As glucan feeding at 0.1% for 1 week is able to enhance the non-specific immunity and disease resistance of catfish efficiently, short-term feeding might be used in farmed catfish diets to enhance disease resistance.

β-lactam antibiotics promote bacterial mutagenesis via an RpoS-mediated reduction in replication fidelity

Science.gov (United States)

Gutierrez, A.; Laureti, L.; Crussard, S.; Abida, H.; Rodríguez-Rojas, A.; Blázquez, J.; Baharoglu, Z.; Mazel, D.; Darfeuille, F.; Vogel, J.; Matic, I.

2013-01-01

Regardless of their targets and modes of action, subinhibitory concentrations of antibiotics can have an impact on cell physiology and trigger a large variety of cellular responses in different bacterial species. Subinhibitory concentrations of β-lactam antibiotics cause reactive oxygen species production and induce PolIV-dependent mutagenesis in Escherichia coli. Here we show that subinhibitory concentrations of β-lactam antibiotics induce the RpoS regulon. RpoS-regulon induction is required for PolIV-dependent mutagenesis because it diminishes the control of DNA-replication fidelity by depleting MutS in E. coli, Vibrio cholerae and Pseudomonas aeruginosa. We also show that in E. coli, the reduction in mismatch-repair activity is mediated by SdsR, the RpoS-controlled small RNA. In summary, we show that mutagenesis induced by subinhibitory concentrations of antibiotics is a genetically controlled process. Because this mutagenesis can generate mutations conferring antibiotic resistance, it should be taken into consideration for the development of more efficient antimicrobial therapeutic strategies. PMID:23511474

Chromosome-encoded narrow-spectrum Ambler class A beta-lactamase GIL-1 from Citrobacter gillenii.

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Naas, Thierry; Aubert, Daniel; Ozcan, Ayla; Nordmann, Patrice

2007-04-01

A novel beta-lactamase gene was cloned from the whole-cell DNA of an enterobacterial Citrobacter gillenii reference strain that displayed a weak narrow-spectrum beta-lactam-resistant phenotype and was expressed in Escherichia coli. It encoded a clavulanic acid-inhibited Ambler class A beta-lactamase, GIL-1, with a pI value of 7.5 and a molecular mass of ca. 29 kDa. GIL-1 had the highest percent amino acid sequence identity with TEM-1 and SHV-1, 77%, and 67%, respectively, and only 46%, 31%, and 32% amino acid sequence identity with CKO-1 (C. koseri), CdiA1 (C. diversus), and SED-1 (C. sedlaki), respectively. The substrate profile of the purified GIL-1 was similar to that of beta-lactamases TEM-1 and SHV-1. The blaGIL-1 gene was chromosomally located, as revealed by I-CeuI experiments, and was constitutively expressed at a low level in C. gillenii. No gene homologous to the regulatory ampR genes of chromosomal class C beta-lactamases was found upstream of the blaGIL-1 gene, which fits the noninducibility of beta-lactamase expression in C. gillenii. Rapid amplification of DNA 5' ends analysis of the promoter region revealed putative promoter sequences that diverge from what has been identified as the consensus sequence in E. coli. The blaGIL-1 gene was part of a 5.5-kb DNA fragment bracketed by a 9-bp duplication and inserted between the d-lactate dehydrogenase gene and the ydbH genes; this DNA fragment was absent in other Citrobacter species. This work further illustrates the heterogeneity of beta-lactamases in Citrobacter spp., which may indicate that the variability of Citrobacter species is greater than expected.

The role of active efflux in antibiotic - resistance of clinical isolates of Helicobacter pylori

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Falsafi T

2009-01-01

Full Text Available Purpose: In gram-negative bacteria, active efflux pumps that excrete drugs can confer resistance to antibiotics however, in Helicobacter pylori this role is not well established. The purpose of this study is to evaluate the role of active efflux in resistance of H. pylori isolates to antibiotics. Materials and Methods: Twelve multiple antibiotic resistant (MAR isolates resistant to at least four antibiotics, including β-lactams, metronidazole, tetracycline, erythromycin, and ciprofloxacin; three resistant to only β-lactams, and two hyper-susceptible isolates, were obtained from screening of 96 clinical isolates of H. pylori . Their minimal inhibitory concentrations (MICs for antibiotics and ethidium-bromide (EtBr were compared in the presence- and absence of a proton-conductor, carbonyl cyanide-m chlorophenyl-hydrazone (CCCP using agar-dilution and disc diffusion. Drug accumulation studies for EtBr and antibiotics were assessed in the presence and absence of CCCP using spectrofluorometry. Results: MIC of EtBr for eight MAR-isolates was decreased two- to four-folds in the presence of CCCP, of which five showed reduced MICs for β-lactam, metronidazole, tetracycline, and ciprofloxacin with CCCP. Accumulation of EtBr by the MAR-isolates was rapid and not dependant on the pattern of multiple resistance. Antibiotic accumulation assay confirmed the presence of energy-dependant efflux of β-lactam, metronidazole, tetracycline, and ciprofloxacin, but no erythromycin in five MAR isolates. Energy-dependant efflux of EtBr or antibiotics was not observed for four MAR-isolates, and three isolates were resistant only to β-lactams. Conclusion: Energy-dependant efflux plays a role in the resistance of H. pylori clinical isolates to structurally unrelated antibiotics in a broadly specific multidrug efflux manner. Difference in the efflux potential of MAR isolates may be related to the presence or absence of functional efflux-pumps in diverse H. pylori

Population Genomic Analysis of 1,777 Extended-Spectrum Beta-Lactamase-Producing Klebsiella pneumoniae Isolates, Houston, Texas: Unexpected Abundance of Clonal Group 307

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S. Wesley Long

2017-05-01

Full Text Available Klebsiella pneumoniae is a major human pathogen responsible for high morbidity and mortality rates. The emergence and spread of strains resistant to multiple antimicrobial agents and documented large nosocomial outbreaks are especially concerning. To develop new therapeutic strategies for K. pneumoniae, it is imperative to understand the population genomic structure of strains causing human infections. To address this knowledge gap, we sequenced the genomes of 1,777 extended-spectrum beta-lactamase-producing K. pneumoniae strains cultured from patients in the 2,000-bed Houston Methodist Hospital system between September 2011 and May 2015, representing a comprehensive, population-based strain sample. Strains of largely uncharacterized clonal group 307 (CG307 caused more infections than those of well-studied epidemic CG258. Strains varied markedly in gene content and had an extensive array of small and very large plasmids, often containing antimicrobial resistance genes. Some patients with multiple strains cultured over time were infected with genetically distinct clones. We identified 15 strains expressing the New Delhi metallo-beta-lactamase 1 (NDM-1 enzyme that confers broad resistance to nearly all beta-lactam antibiotics. Transcriptome sequencing analysis of 10 phylogenetically diverse strains showed that the global transcriptome of each strain was unique and highly variable. Experimental mouse infection provided new information about immunological parameters of host-pathogen interaction. We exploited the large data set to develop whole-genome sequence-based classifiers that accurately predict clinical antimicrobial resistance for 12 of the 16 antibiotics tested. We conclude that analysis of large, comprehensive, population-based strain samples can assist understanding of the molecular diversity of these organisms and contribute to enhanced translational research.

High beta tokamak operation in DIII-D limited at low density/collisionality by resistive tearing modes

International Nuclear Information System (INIS)

La Haye, R.J.; Lao, L.L.; Strait, E.J.; Taylor, T.S.

1997-01-01

The maximum operational high beta in single-null divertor (SND) long pulse tokamak discharges in the DIII-D tokamak with a cross-sectional shape similar to the proposed International Thermonuclear Experimental Reactor (ITER) device is found to be limited by the onset of resistive instabilities that have the characteristics of neoclassically destabilized tearing modes. There is a soft limit due to the onset of an m/n=3/2 rotating tearing mode that saturates at low amplitude and a hard limit at slightly higher beta due to the onset of an m/n=2/1 rotating tearing mode that grows, slows down and locks. By operating at higher density and thus collisionality, the practical beta limit due to resistive tearing modes approaches the ideal magnetohydrodynamic (MHD) limit. (author). 15 refs, 4 figs

Should the patients colonized with extended-spectrum beta-lactamase-producing Gram-negative bacilli (E-GNB) coming to hospital from the community with pneumonia get anti-E-GNB active empirical treatment?

Science.gov (United States)

Peterlin, Lara; Žagar, Mateja; Lejko Zupanc, Tatjana; Paladin, Marija; Beović, Bojana

2017-10-01

Extended-spectrum beta-lactamases are responsible for resistance of Gram-negative bacilli to several beta-lactam antibiotics, including those prescribed for treatment pneumonia. To evaluate the importance of colonization with E-GNB for the choice of empirical treatment we performed a retrospective case-control study including 156 patients, hospitalized for treatment of pneumonia from 2009 through 2013. Empirical treatment success and in-hospital survival were significantly lower in patients colonized with E-GNB compared to non-colonized (p = 0.002, p = 0.035). When comparing subgroups of colonized patients, treatment success was significantly lower in patients who were colonized with E-GNB resistant to empirical antibiotic (p = 0.010), but not in those colonized by E-GNB susceptible to empirically given antibiotic (p = 0.104). Difference in in-hospital mortality was insignificant in both subgroups (p = 0.056, p = 0.331). The results of study suggest that an anti-E-GNB active antibiotic should be used for empirical treatment of pneumonia in E-GNB colonized patients.

Enzyme activities and antibiotic susceptibility of colonial variants of Bacillus subtilis and Bacillus licheniformis.

OpenAIRE

Carlisle, G E; Falkinham, J O

1989-01-01

A nonmucoid colonial variant of a mucoid Bacillus subtilis strain produced less amylase activity and a transparent colonial variant of a B. licheniformis strain produced less protease activity compared with their parents. Antibiotic susceptibility patterns of the colonial variants differed, and increased resistance to beta-lactam antibiotics was correlated with increased production of extracellular beta-lactamase.

Oxidation of β-lactam antibiotics by peracetic acid: Reaction kinetics, product and pathway evaluation.

Science.gov (United States)

Zhang, Kejia; Zhou, Xinyan; Du, Penghui; Zhang, Tuqiao; Cai, Meiquan; Sun, Peizhe; Huang, Ching-Hua

2017-10-15

Peracetic acid (PAA) is a disinfection oxidant used in many industries including wastewater treatment. β-Lactams, a group of widely prescribed antibiotics, are frequently detected in wastewater effluents and surface waters. The reaction kinetics and transformation of seven β-lactams (cefalexin (CFX), cefadroxil (CFR), cefapirin (CFP), cephalothin (CFT), ampicillin (AMP), amoxicillin (AMX) and penicillin G (PG)) toward PAA were investigated to elucidate the behavior of β-lactams during PAA oxidation processes. The reaction follows second-order kinetics and is much faster at pH 5 and 7 than at pH 9 due to speciation of PAA. Reactivity to PAA follows the order of CFR ∼ CFX > AMP ∼ AMX > CFT ∼ CFP ∼ PG and is related to β-lactam's nucleophilicity. The thioether sulfur of β-lactams is attacked by PAA to generate sulfoxide products. Presence of the phenylglycinyl amino group on β-lactams can significantly influence electron distribution and the highest occupied molecular orbital (HOMO) location and energy in ways that enhance the reactivity to PAA. Reaction rate constants obtained in clean water matrix can be used to accurately model the decay of β-lactams by PAA in surface water matrix and only slightly overestimate the decay in wastewater matrix. Results of this study indicate that the oxidative transformation of β-lactams by PAA can be expected under appropriate wastewater treatment conditions. Copyright © 2017. Published by Elsevier Ltd.

The mecillinam resistome reveals a role for peptidoglycan endopeptidases in stimulating cell wall synthesis in Escherichia coli.

Science.gov (United States)

Lai, Ghee Chuan; Cho, Hongbaek; Bernhardt, Thomas G

2017-07-01

Bacterial cells are typically surrounded by an net-like macromolecule called the cell wall constructed from the heteropolymer peptidoglycan (PG). Biogenesis of this matrix is the target of penicillin and related beta-lactams. These drugs inhibit the transpeptidase activity of PG synthases called penicillin-binding proteins (PBPs), preventing the crosslinking of nascent wall material into the existing network. The beta-lactam mecillinam specifically targets the PBP2 enzyme in the cell elongation machinery of Escherichia coli. Low-throughput selections for mecillinam resistance have historically been useful in defining mechanisms involved in cell wall biogenesis and the killing activity of beta-lactam antibiotics. Here, we used transposon-sequencing (Tn-Seq) as a high-throughput method to identify nearly all mecillinam resistance loci in the E. coli genome, providing a comprehensive resource for uncovering new mechanisms underlying PG assembly and drug resistance. Induction of the stringent response or the Rcs envelope stress response has been previously implicated in mecillinam resistance. We therefore also performed the Tn-Seq analysis in mutants defective for these responses in addition to wild-type cells. Thus, the utility of the dataset was greatly enhanced by determining the stress response dependence of each resistance locus in the resistome. Reasoning that stress response-independent resistance loci are those most likely to identify direct modulators of cell wall biogenesis, we focused our downstream analysis on this subset of the resistome. Characterization of one of these alleles led to the surprising discovery that the overproduction of endopeptidase enzymes that cleave crosslinks in the cell wall promotes mecillinam resistance by stimulating PG synthesis by a subset of PBPs. Our analysis of this activation mechanism suggests that, contrary to the prevailing view in the field, PG synthases and PG cleaving enzymes need not function in multi-enzyme complexes

The mecillinam resistome reveals a role for peptidoglycan endopeptidases in stimulating cell wall synthesis in Escherichia coli.

Directory of Open Access Journals (Sweden)

Ghee Chuan Lai

2017-07-01

Full Text Available Bacterial cells are typically surrounded by an net-like macromolecule called the cell wall constructed from the heteropolymer peptidoglycan (PG. Biogenesis of this matrix is the target of penicillin and related beta-lactams. These drugs inhibit the transpeptidase activity of PG synthases called penicillin-binding proteins (PBPs, preventing the crosslinking of nascent wall material into the existing network. The beta-lactam mecillinam specifically targets the PBP2 enzyme in the cell elongation machinery of Escherichia coli. Low-throughput selections for mecillinam resistance have historically been useful in defining mechanisms involved in cell wall biogenesis and the killing activity of beta-lactam antibiotics. Here, we used transposon-sequencing (Tn-Seq as a high-throughput method to identify nearly all mecillinam resistance loci in the E. coli genome, providing a comprehensive resource for uncovering new mechanisms underlying PG assembly and drug resistance. Induction of the stringent response or the Rcs envelope stress response has been previously implicated in mecillinam resistance. We therefore also performed the Tn-Seq analysis in mutants defective for these responses in addition to wild-type cells. Thus, the utility of the dataset was greatly enhanced by determining the stress response dependence of each resistance locus in the resistome. Reasoning that stress response-independent resistance loci are those most likely to identify direct modulators of cell wall biogenesis, we focused our downstream analysis on this subset of the resistome. Characterization of one of these alleles led to the surprising discovery that the overproduction of endopeptidase enzymes that cleave crosslinks in the cell wall promotes mecillinam resistance by stimulating PG synthesis by a subset of PBPs. Our analysis of this activation mechanism suggests that, contrary to the prevailing view in the field, PG synthases and PG cleaving enzymes need not function in multi

Interaction with beta-arrestin determines the difference in internalization behavor between beta1- and beta2-adrenergic receptors.

Science.gov (United States)

Shiina, T; Kawasaki, A; Nagao, T; Kurose, H

2000-09-15

The beta(1)-adrenergic receptor (beta(1)AR) shows the resistance to agonist-induced internalization. As beta-arrestin is important for internalization, we examine the interaction of beta-arrestin with beta(1)AR with three different methods: intracellular trafficking of beta-arrestin, binding of in vitro translated beta-arrestin to intracellular domains of beta(1)- and beta(2)ARs, and inhibition of betaAR-stimulated adenylyl cyclase activities by beta-arrestin. The green fluorescent protein-tagged beta-arrestin 2 translocates to and stays at the plasma membrane by beta(2)AR stimulation. Although green fluorescent protein-tagged beta-arrestin 2 also translocates to the plasma membrane, it returns to the cytoplasm 10-30 min after beta(1)AR stimulation. The binding of in vitro translated beta-arrestin 1 and beta-arrestin 2 to the third intracellular loop and the carboxyl tail of beta(1)AR is lower than that of beta(2)AR. The fusion protein of beta-arrestin 1 with glutathione S-transferase inhibits the beta(1)- and beta(2)AR-stimulated adenylyl cyclase activities, although inhibition of the beta(1)AR-stimulated activity requires a higher concentration of the fusion protein than that of the beta(2)AR-stimulated activity. These results suggest that weak interaction of beta(1)AR with beta-arrestins explains the resistance to agonist-induced internalization. This is further supported by the finding that beta-arrestin can induce internalization of beta(1)AR when beta-arrestin 1 does not dissociate from beta(1)AR by fusing to the carboxyl tail of beta(1)AR.

Antimicrobial resistance and detection of mecA and blaZ genes in coagulase-negative Staphylococcus isolated from bovine mastitis

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Lidiane C. Soares

2012-08-01

Full Text Available The present study evaluated the pheno- and genotypical antimicrobial resistance profile of coagulase-negative Staphylococcus (CNS species isolated from dairy cows milk, specially concerning to oxacillin. Of 100 CNS isolates, the S. xylosus was the prevalent species, followed by S. cohnii, S. hominis, S. capitis and S. haemolyticus. Only 6% were phenotypically susceptible to the antimicrobial agents tested in disk diffusion assay. Penicillin and ampicillin resistance rates were significantly higher than others antimicrobials. Four isolates were positive to mecA gene (4%, all represented by the S. xylosus species. The blaZ gene was detected in 16% of the isolates (16/100. It was noticed that all mecA + were also positive to this gene and the presence of both genes was correlated to phenotypic beta-lactamic resistance. We conclude that CNS species from bovine milk presented significantly distinct antimicrobial resistance profiles, evaluated by phenotypic and genotypic tests, which has implications for treatment and management decisions.

Intracellular forms of menadione-dependent small-colony variants of methicillin-resistant Staphylococcus aureus are hypersusceptible to β-lactams in a THP-1 cell model due to cooperation between vacuolar acidic pH and oxidant species.

Science.gov (United States)

Garcia, Laetitia G; Lemaire, Sandrine; Kahl, Barbara C; Becker, Karsten; Proctor, Richard A; Tulkens, Paul M; Van Bambeke, Françoise

2012-12-01

Phagocytosed methicillin-resistant Staphylococcus aureus (MRSA) are susceptible to β-lactams because of an acid-induced conformational change of penicillin-binding protein (PBP) 2a within phagolysosomes. We have examined whether this mechanism applies to menD and hemB small-colony variants (SCVs) of the COL MRSA strain, using cloxacillin, meropenem, doripenem, and vancomycin as comparator. Intracellularly, the change in cfu from post-phagocytosis inoculum was measured after 24 h of incubation with antibiotics combined or not with N-acetylcysteine (NAC; oxidant species scavenger); the relative potency (C(s)) was calculated from the Hill equation of concentration-response curves. Extracellularly, the effect of a pre-incubation with H(2)O(2) was determined on MICs and killing at pH 7.4 and 5.5. Intracellularly, the β-lactam C(s) was similar for the COL strain and the hemB mutant and not modified or slightly decreased (2- to 16-fold) by NAC. In contrast, the C(s) was 100- to 900-fold lower for the menD mutant, but similar to that for the COL strain when NAC was present. Extracellularly, β-lactam MICs were markedly reduced at pH 5.5 for the parental strain and the haemin-supplemented hemB mutant, with limited additional effect of pre-incubation with H(2)O(2). In contrast, MICs remained elevated at pH 5.5 for the menD mutant (supplemented with menadione sodium bisulphite or not), but were 7-10 dilutions lower after pre-incubation with H(2)O(2). Vancomycin MICs were unaltered in all conditions, with no marked effect of NAC on C(s). Cooperation between acidic pH and oxidant species confers high potency to β-lactams against intracellular forms of menD SCVs of MRSA.

Homologous expression of a mutated beta-tubulin gene does not confer benomyl resistance on Trichoderma virens.

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Mukherjee, M; Hadar, R; Mukherjee, P K; Horwitz, B A

2003-01-01

To clone the beta-tubulins and to induce resistance to benzimidazoles in the biocontrol fungus Trichoderma virens through site-directed mutagenesis. Two beta-tubulin genes have been cloned using PCR amplification followed by the screening of a T. virens cDNA library. The full-length cDNA clones, coding for 445 and 446 amino acids, have been designated as T. virens tub1 and T. virens tub2. A sequence alignment of these two tubulins with tubulins from other filamentous fungi has shown the presence of some unique amino acid sequences not found in those positions in other beta-tubulins. Constitutive expression of the tub2 gene with a histidine to tyrosine substitution at position 6 (known to impart benomyl/methyl benzimadazol-2-yl carbamate resistance in other fungi), under the Pgpd promoter of Aspergillus nidulans, did not impart resistance to benomyl. The homologous expression of tub2 gene with a histidine to tyrosine mutation at position +6, which is known to impart benomyl tolerance in other fungi, does not impart resistance in T. virens. Unlike other Trichoderma spp., T. virens, has been difficult to mutate for benomyl tolerance. The present study, through site-directed mutagenesis, shows that a mutation known to impart benomyl tolerance in T. viride and other fungi does not impart resistance in this fungus. Understanding the mechanisms of this phenomenon will have a profound impact in plant-disease management, as many plant pathogenic fungi develop resistance to this group of fungicides forcing its withdrawal after a short period of use.

Substrate-induced inactivation of the OXA2 beta-lactamase.

Science.gov (United States)

Ledent, P; Frère, J M

1993-01-01

The hydrolysis time courses of 22 beta-lactam antibiotics by the class D OXA2 beta-lactamase were studied. Among these, only three appeared to correspond to the integrated Henri-Michaelis equation. 'Burst' kinetics, implying branched pathways, were observed with most penicillins, cephalosporins and with flomoxef and imipenem. Kinetic parameters characteristic of the different phases of the hydrolysis were determined for some substrates. Mechanisms generally accepted to explain such reversible partial inactivations involving branches at either the free enzyme or the acyl-enzyme were inadequate to explain the enzyme behaviour. The hydrolysis of imipenem was characterized by the occurrence of two 'bursts', and that of nitrocefin by a partial substrate-induced inactivation complicated by a competitive inhibition by the hydrolysis product. PMID:8240304

Functional Repertoire of Antibiotic Resistance Genes in Antibiotic Manufacturing Effluents and Receiving Freshwater Sediments

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Juan J. González-Plaza

2018-01-01

Full Text Available Environments polluted by direct discharges of effluents from antibiotic manufacturing are important reservoirs for antibiotic resistance genes (ARGs, which could potentially be transferred to human pathogens. However, our knowledge about the identity and diversity of ARGs in such polluted environments remains limited. We applied functional metagenomics to explore the resistome of two Croatian antibiotic manufacturing effluents and sediments collected upstream of and at the effluent discharge sites. Metagenomic libraries built from an azithromycin-production site were screened for resistance to macrolide antibiotics, whereas the libraries from a site producing veterinary antibiotics were screened for resistance to sulfonamides, tetracyclines, trimethoprim, and beta-lactams. Functional analysis of eight libraries identified a total of 82 unique, often clinically relevant ARGs, which were frequently found in clusters and flanked by mobile genetic elements. The majority of macrolide resistance genes identified from matrices exposed to high levels of macrolides were similar to known genes encoding ribosomal protection proteins, macrolide phosphotransferases, and transporters. Potentially novel macrolide resistance genes included one most similar to a 23S rRNA methyltransferase from Clostridium and another, derived from upstream unpolluted sediment, to a GTPase HflX from Emergencia. In libraries deriving from sediments exposed to lower levels of veterinary antibiotics, we found 8 potentially novel ARGs, including dihydrofolate reductases and beta-lactamases from classes A, B, and D. In addition, we detected 7 potentially novel ARGs in upstream sediment, including thymidylate synthases, dihydrofolate reductases, and class D beta-lactamase. Taken together, in addition to finding known gene types, we report the discovery of novel and diverse ARGs in antibiotic-polluted industrial effluents and sediments, providing a qualitative basis for monitoring the

Functional Repertoire of Antibiotic Resistance Genes in Antibiotic Manufacturing Effluents and Receiving Freshwater Sediments

Science.gov (United States)

González-Plaza, Juan J.; Šimatović, Ana; Milaković, Milena; Bielen, Ana; Wichmann, Fabienne; Udiković-Kolić, Nikolina

2018-01-01

Environments polluted by direct discharges of effluents from antibiotic manufacturing are important reservoirs for antibiotic resistance genes (ARGs), which could potentially be transferred to human pathogens. However, our knowledge about the identity and diversity of ARGs in such polluted environments remains limited. We applied functional metagenomics to explore the resistome of two Croatian antibiotic manufacturing effluents and sediments collected upstream of and at the effluent discharge sites. Metagenomic libraries built from an azithromycin-production site were screened for resistance to macrolide antibiotics, whereas the libraries from a site producing veterinary antibiotics were screened for resistance to sulfonamides, tetracyclines, trimethoprim, and beta-lactams. Functional analysis of eight libraries identified a total of 82 unique, often clinically relevant ARGs, which were frequently found in clusters and flanked by mobile genetic elements. The majority of macrolide resistance genes identified from matrices exposed to high levels of macrolides were similar to known genes encoding ribosomal protection proteins, macrolide phosphotransferases, and transporters. Potentially novel macrolide resistance genes included one most similar to a 23S rRNA methyltransferase from Clostridium and another, derived from upstream unpolluted sediment, to a GTPase HflX from Emergencia. In libraries deriving from sediments exposed to lower levels of veterinary antibiotics, we found 8 potentially novel ARGs, including dihydrofolate reductases and beta-lactamases from classes A, B, and D. In addition, we detected 7 potentially novel ARGs in upstream sediment, including thymidylate synthases, dihydrofolate reductases, and class D beta-lactamase. Taken together, in addition to finding known gene types, we report the discovery of novel and diverse ARGs in antibiotic-polluted industrial effluents and sediments, providing a qualitative basis for monitoring the dispersal of ARGs

SME-type carbapenem-hydrolyzing class A beta-lactamases from geographically diverse Serratia marcescens strains.

Science.gov (United States)

Queenan, A M; Torres-Viera, C; Gold, H S; Carmeli, Y; Eliopoulos, G M; Moellering, R C; Quinn, J P; Hindler, J; Medeiros, A A; Bush, K

2000-11-01

Three sets of carbapenem-resistant Serratia marcescens isolates have been identified in the United States: 1 isolate in Minnesota in 1985 (before approval of carbapenems for clinical use), 5 isolates in Los Angeles (University of California at Los Angeles [UCLA]) in 1992, and 19 isolates in Boston from 1994 to 1999. All isolates tested produced two beta-lactamases, an AmpC-type enzyme with pI values of 8.6 to 9.0 and one with a pI value of approximately 9.5. The enzyme with the higher pI in each strain hydrolyzed carbapenems and was not inhibited by EDTA, similar to the chromosomal class A SME-1 beta-lactamase isolated from the 1982 London strain S. marcescens S6. The genes encoding the carbapenem-hydrolyzing enzymes were cloned in Escherichia coli and sequenced. The enzyme from the Minnesota isolate had an amino acid sequence identical to that of SME-1. The isolates from Boston and UCLA produced SME-2, an enzyme with a single amino acid change relative to SME-1, a substitution from valine to glutamine at position 207. Purified SME enzymes from the U. S. isolates had beta-lactam hydrolysis profiles similar to that of the London SME-1 enzyme. Pulsed-field gel electrophoresis analysis revealed that the isolates showed some similarity but differed by at least three genetic events. In conclusion, a family of rare class A carbapenem-hydrolyzing beta-lactamases first described in London has now been identified in S. marcescens isolates across the United States.

Carbapenemase-producerende enterobacteriën in Nederland : Onopgemerkte versprewiding naar verschillende regio's.

NARCIS (Netherlands)

Leenstra, T; Bosch, T; Vlek, A L; Bonten, M J M; van der Lubben, I M; de Greeff, S C

2017-01-01

- Carbapenemase producing Enterobacteriaceae (CPE), including Klebsiella pneumoniae and Escherichia coli, are only sporadically seen in the Netherlands and then mainly in patients who have been transferred from foreign hospitals.- CPE are resistant to virtually all beta-lactam antibiotics, including

Beta Lactamase Producing Clostridium perfringens Bacteremia in an Elderly Man with Acute Pancreatitis

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Rashmi Mishra

2016-01-01

Full Text Available Clostridium perfringens bacteremia is associated with adverse outcomes. Known risk factors include chronic kidney disease, malignancy, diabetes mellitus, and gastrointestinal disease. We present a 74-year-old man admitted with confusion, vomiting, and abdominal pain. Exam revealed tachycardia, hypotension, lethargy, distended abdomen, and cold extremities. He required intubation and aggressive resuscitation for septic shock. Laboratory data showed leukocytosis, metabolic acidosis, acute kidney injury, and elevated lipase. CT scan of abdomen revealed acute pancreatitis and small bowel ileus. He was started on vancomycin and piperacillin-tazobactam. Initial blood cultures were positive for C. perfringens on day five. Metronidazole and clindamycin were added to the regimen. Repeat CT (day 7 revealed pancreatic necrosis. The patient developed profound circulatory shock requiring multiple vasopressors, renal failure requiring dialysis, and bacteremia with vancomycin-resistant enterococci. Hemodynamic instability precluded surgical intervention and he succumbed to multiorgan failure. Interestingly, our isolate was beta lactamase producing. We review the epidemiology, risk factors, presentation, and management of C. perfringens bacteremia. This case indicates a need for high clinical suspicion for clostridial sepsis and that extended spectrum beta lactam antibiotic coverage may be inadequate and should be supplemented with use of clindamycin or metronidazole if culture is positive, until sensitivities are known.

[New antibacterial agents on the market and in the pipeline].

Science.gov (United States)

Kern, W V

2015-11-01

After some years of stagnation there have been several new successful developments in the field of antibacterial agents. Most of these new developments have been in conventional antibacterial classes. New drugs among the beta-lactam agents are methicillin-resistant Staphylococcus aureus (MRSA) active cephalosporins (ceftaroline and ceftobiprole) and new combinations of beta-lactam with beta-lactamase inhibitors (ceftolozane/tazobactam, ceftazidime/avibactam, imipenem/relebactam and meropenem/RPX7009). New developments can also be observed among oxazolidinones (tedizolid, radezolid, cadazolid and MRX-I), macrolides/ketolides (modithromycin and solithromycin), aminoglycosides (plazomicin), quinolones (nemonoxacin, delafloxacin and avarofloxacin), tetracyclines (omadacycline and eravacycline) as well as among glycopeptides and lipopeptides (oritavancin, telavancin, dalbavancin and surotomycin). New agents in a very early developmental phase are FabI inhibitors, endolysines, peptidomimetics, lipid A inhibitors, methionyl-tRNA synthetase inhibitors and teixobactin.

High β-Lactamase Levels Change the Pharmacodynamics of β-Lactam Antibiotics in Pseudomonas aeruginosa Biofilms

Science.gov (United States)

Ciofu, Oana; Yang, Liang; Wu, Hong; Song, Zhijun; Oliver, Antonio; Høiby, Niels

2013-01-01

Resistance to β-lactam antibiotics is a frequent problem in Pseudomonas aeruginosa lung infection of cystic fibrosis (CF) patients. This resistance is mainly due to the hyperproduction of chromosomally encoded β-lactamase and biofilm formation. The purpose of this study was to investigate the role of β-lactamase in the pharmacokinetics (PK) and pharmacodynamics (PD) of ceftazidime and imipenem on P. aeruginosa biofilms. P. aeruginosa PAO1 and its corresponding β-lactamase-overproducing mutant, PAΔDDh2Dh3, were used in this study. Biofilms of these two strains in flow chambers, microtiter plates, and on alginate beads were treated with different concentrations of ceftazidime and imipenem. The kinetics of antibiotics on the biofilms was investigated in vitro by time-kill methods. Time-dependent killing of ceftazidime was observed in PAO1 biofilms, but concentration-dependent killing activity of ceftazidime was observed for β-lactamase-overproducing biofilms of P. aeruginosa in all three models. Ceftazidime showed time-dependent killing on planktonic PAO1 and PAΔDDh2Dh3. This difference is probably due to the special distribution and accumulation in the biofilm matrix of β-lactamase, which can hydrolyze the β-lactam antibiotics. The PK/PD indices of the AUC/MBIC and Cmax/MBIC (AUC is the area under concentration-time curve, MBIC is the minimal biofilm-inhibitory concentration, and Cmax is the maximum concentration of drug in serum) are probably the best parameters to describe the effect of ceftazidime in β-lactamase-overproducing P. aeruginosa biofilms. Meanwhile, imipenem showed time-dependent killing on both PAO1 and PAΔDDh2Dh3 biofilms. An inoculum effect of β-lactams was found for both planktonic and biofilm P. aeruginosa cells. The inoculum effect of ceftazidime for the β-lactamase-overproducing mutant PAΔDDh2Dh3 biofilms was more obvious than for PAO1 biofilms, with a requirement of higher antibiotic concentration and a longer period of treatment

Hygiene quality and presence of ESBL-producing Escherichia coli in raw food diets for dogs

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Oskar Nilsson

2015-10-01

CMY-2 group and only one of them was also resistant to a non-beta-lactam antibiotic. Conclusion: The results of this study indicate that raw food diets could be a source of ESC-resistant E. coli to dogs and highlight the need for maintaining good hygiene when handling these products to prevent infection.

Finite beta and compressibility effects on stability of resistive modes in toroidal geometry

International Nuclear Information System (INIS)

Leboeuf, J-N.G.; Kurita, Gen-ichi.

1998-03-01

Linear resistive stability results obtained from the toroidal magnetohydrodynamic codes FAR developed at the Oak Ridge National Laboratory in United States of America and AEOLUS developed at the Japan Atomic Energy Research Institute are compared for carefully constructed benchmark profiles and parameters. These are unstable to a tearing mode with toroidal mode number n=1. The eigenvalues and eigenfunctions calculated with both codes are in close agreement and show that the effect of compressibility is weak for these modes. The effect of finite plasma beta is considered, and the eigenvalues calculated by the FAR and AEOLUS codes also show good agreement. It is shown that the finite beta has a stabilizing effect on the toroidal tearing mode, but that the compressibility also has little effect on finite beta tearing modes. (author)

Digestive tract colonization by multidrug-resistant Enterobacteriaceae in travellers: An update.

Science.gov (United States)

Ruppé, Etienne; Andremont, Antoine; Armand-Lefèvre, Laurence

Enterobacteriaceae have become increasingly resistant, especially due to the acquisition and spread of extended-spectrum beta-lactamases (ESBLs), which confer resistance to the majority of beta-lactams. Multi-resistant Enterobacteriaceae (MRE) were first isolated in hospitals, but now they are disseminating in the community setting, mostly in low and middle income countries. Consequently, the increasing number of international travels leads to the importation of MRE from high-prevalence to low-prevalence countries. The Pubmed database was used to conduct research from 1980 to 2016 by combining the following key words: travel, antibiotic resistance, ESBL, Enterobacteriaceae, genomic, metagenomic, urinary tract infection, infection. The research found that the MRE acquisition rates in healthy travellers from low-prevalence countries ranged from 21% to 51% depending on the study design and the visited geographic regions. After a trip to Asia and especially to South Asia, the acquisition rate could reach 85%. A trip to Africa or to the Middle East was associated with lower rates but still worrisome (13-44%). Digestive disorder, diarrhoea and antibiotics used during travel are major risks factors associated with the acquisition of MRE. Travel to endemic areas has also been identified as a risk factor for MRE infection, including urinary tract infections. Travellers are at high risk of MRE acquisition and consequently of MRE infection. This risk should not be ignored by general practitioners. To reduce the risk of acquisition and subsequent transmission to relatives, travellers should be given recommendations prior to their travel. Copyright © 2017. Published by Elsevier Ltd.

Fermentation conditions that affect clavulanic acid production in Streptomyces clavuligerus: a systematic review

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Hooi-Leng eSer

2016-04-01

Full Text Available The β-lactamase inhibitor, clavulanic acid is frequently used in combination with β-lactam antibiotics to treat a wide spectrum of infectious diseases. Clavulanic acid prevents drug resistance by pathogens against these β-lactam antibiotics by preventing the degradation of the β-lactam ring, thus ensuring eradication of these harmful microorganisms from the host. This systematic review provides an overview on the fermentation conditions that affect the production of clavulanic acid in the firstly described producer, Streptomyces clavuligerus. A thorough search was conducted using predefined terms in several electronic databases (PubMed, Medline, ScienceDirect, EBSCO, from database inception to June 30th 2015. Studies must involve wild-type Streptomyces clavuligerus, and full texts needed to be available. A total of 29 eligible articles were identified. Based on the literature, several factors were identified that could affect the production of clavulanic acid in S. clavuligerus. The addition of glycerol or other vegetable oils (e.g. olive oil, corn oil could potentially affect clavulanic acid production. Furthermore, some amino acids such as arginine and ornithine, could serve as potential precursors to increase clavulanic acid yield. The comparison of different fermentation systems revealed that fed-batch fermentation yields higher amounts of clavulanic acid as compared to batch fermentation, probably due to the maintenance of substrates and constant monitoring of certain entities (such as pH, oxygen availability, etc.. Overall, these findings provide vital knowledge and insight that could assist media optimization and fermentation design for clavulanic acid production in S. clavuligerus.

Antianaerobic Antimicrobials: Spectrum and Susceptibility Testing

Science.gov (United States)

Wexler, Hannah M.; Goldstein, Ellie J. C.

2013-01-01

SUMMARY Susceptibility testing of anaerobic bacteria recovered from selected cases can influence the choice of antimicrobial therapy. The Clinical and Laboratory Standards Institute (CLSI) has standardized many laboratory procedures, including anaerobic susceptibility testing (AST), and has published documents for AST. The standardization of testing methods by the CLSI allows comparisons of resistance trends among various laboratories. Susceptibility testing should be performed on organisms recovered from sterile body sites, those that are isolated in pure culture, or those that are clinically important and have variable or unique susceptibility patterns. Organisms that should be considered for individual isolate testing include highly virulent pathogens for which susceptibility cannot be predicted, such as Bacteroides, Prevotella, Fusobacterium, and Clostridium spp.; Bilophila wadsworthia; and Sutterella wadsworthensis. This review describes the current methods for AST in research and reference laboratories. These methods include the use of agar dilution, broth microdilution, Etest, and the spiral gradient endpoint system. The antimicrobials potentially effective against anaerobic bacteria include beta-lactams, combinations of beta-lactams and beta-lactamase inhibitors, metronidazole, chloramphenicol, clindamycin, macrolides, tetracyclines, and fluoroquinolones. The spectrum of efficacy, antimicrobial resistance mechanisms, and resistance patterns against these agents are described. PMID:23824372

Comparative activities of telavancin combined with nafcillin, imipenem, and gentamicin against Staphylococcus aureus.

Science.gov (United States)

Leonard, Steven N; Supple, Megan E; Gandhi, Ronak G; Patel, Meghna D

2013-06-01

Beta-lactams enhance the killing activity of vancomycin. Due to structural and mechanistic similarities between vancomycin and telavancin, we investigated the activity of telavancin combined with nafcillin and imipenem compared to the known synergistic combination of telavancin and gentamicin. Thirty strains of Staphylococcus aureus, 10 methicillin-susceptible S. aureus (MSSA), 10 methicillin-resistant S. aureus (MRSA), and 10 heterogeneously vancomycin-intermediate S. aureus (hVISA), were tested for synergy by time-kill methodology. Six strains (2 each of MSSA, MRSA, and hVISA) were further evaluated in an in vitro pharmacokinetic/pharmacodynamic (PK/PD) model with simulated regimens of 10 mg/kg of body weight of telavancin once daily alone and combined with 2 g nafcillin every 4 h, 500 mg imipenem every 6 h, or 5 mg/kg gentamicin once daily over 72 h. In the synergy test, 67% of strains displayed synergy with the combination of telavancin and gentamicin, 70% with telavancin and nafcillin, and 63% with telavancin and imipenem. In the PK/PD model, the activities of all three combinations against MRSA and hVISA were superior to all individual drugs alone (P ≤ 0.002) and were similar to each other (P ≥ 0.187). The activities of all three combinations against MSSA were generally similar to each other except for one strain where the combination of telavancin and imipenem was superior to all other regimens (P ≤ 0.011). The activity of the combination of telavancin and beta-lactam agents was similar to that of telavancin and gentamicin against S. aureus, including resistant strains. Because beta-lactam combinations are less likely to be nephrotoxic than telavancin plus gentamicin, these beta-lactam combinations may have clinical utility.

Distinct effects of struvite and biochar amendment on the class 1 integron antibiotic resistance gene cassettes in phyllosphere and rhizosphere.

Science.gov (United States)

An, Xin-Li; Chen, Qing-Lin; Zhu, Dong; Su, Jian-Qiang

2018-08-01

Struvite recovered from wastewater is promising for recycling phosphorus into soil as fertilizers. However, struvite application may prompt the proliferation of antibiotic resistance in soil and plant. This study examined the impacts of struvite application and biochar amendment on integrons abundance and gene cassette contexts in rhizosphere soil and phyllosphere using quantitative PCR and clone library analysis. Microcosm experiments revealed that class 1 integron was the most prevalent in all samples, with higher concentration and higher relative abundance in rhizosphere than those in phyllosphere. The majority of resistance gene cassettes were associated with genes encoding resistance to aminoglycosides, beta-lactams and chloramphenicols. Struvite application significantly increased the genetic diversity of antibiotic resistance gene cassettes in both rhizosphere and phyllosphere. However, biochar amendment attenuated the increasing effect of struvite application exerting on the class 1 integron antibiotic resistance gene cassette pool in phyllosphere. These findings highlighted human activities to be the source of integron gene cassette pool and raised the possibility of using biochar amendment as an alternative mean for mitigating antibiotic resistance in environments. Copyright © 2018 Elsevier B.V. All rights reserved.

Rapid examination of the kinetic process of intramolecular lactamization of gabapentin using DSC-FTIR

International Nuclear Information System (INIS)

Hsu, C.-H.; Lin, S.-Y.

2009-01-01

The thermal stability and thermodynamics of gabapentin (GBP) in the solid state were investigated by DSC and TG techniques, and FTIR microspectroscopy. The detailed intramolecular lactamization process of GBP to form gabapentin-lactam (GBP-L) was also determined by thermal FTIR microspectroscopy. GBP exhibited a DSC endothermic peak at 169 deg. C. The weight loss in TG curve of GBP suggested that the evaporation process of water liberated via intramolecular lactamization was simultaneously combined with the evaporation process of GBP-L having a DSC endothermic peak at 91 deg. C. A thermal FTIR microspectroscopy clearly evidenced the IR spectra at 3350 cm -1 for water liberated and at 1701 cm -1 for lactam structure formed due to the lactam formation of GBP. This study indicates that the activation energy for combined processes of intramolecular lactamization of GBP and evaporation of GBP-L was about 114.3 ± 23.3 kJ/mol, but for the evaporation of GBP-L alone was 76.2 ± 1.5 kJ/mol. A powerful simultaneous DSC-FTIR combined technique was easily used to quickly examine the detailed kinetic processes of intramolecular cyclization of GPB and evaporation of GBP-L in the solid state

Asymmetric Synthesis and Antimicrobial Activity of Some New Mono and Bicyclic β-Lactams

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A. Taslimi

2004-11-01

Full Text Available Reaction of the amino acid D-phenylalanine ethyl ester (4 with cinnamaldehyde gave chiral Schiff base 5, which underwent an asymmetric Staudinger [2+2] cycloaddition reaction with phthalimidoacetyl chloride to give the monocyclic β-lactam 6 as a single stereoisomer. Ozonolysis of 6 followed by reduction with lithium aluminum tri(tert-butoxy hydride afforded the hydroxymethyl β-lactam 8. Treatment of 8 with methansulfonyl chloride gave the mesylated monocyclic β-lactam 9, which was converted to the bicyclic β-lactam 10 upon treatment with 1,8-diazabicyclo[5,4.0] undec- 7-ene (DBU. Deprotection of the phthalimido group in β-lactams 6 and 10 by methylhydrazine and subsequent acylation of the free amino β-lactams with different acyl chlorides in the presence of pyridine afforded mono and bicyclic β-lactams 14a-d and 15a-d respectively. The compounds prepared were tested against Escherichia coli, Staphilococcus citrus, Klebsiella pneumanie and Bacillus subtillis. Some of these compounds showed potential antimicrobial activities.

The causes and consequences of antibiotic resistance evolution in microbial pathogens

DEFF Research Database (Denmark)

Jochumsen, Nicholas

pleiotropy as they conferred a decreased growth rate in the absence of colistin and also rendered the colistin resistant strains susceptible towards all tested classes of β-lactams. The results suggest that colistin/β-lactam combination therapy could be used to reduce the risk of resistance evolution during......The evolution of antimicrobial resistance in bacterial pathogens is a growing global health problem that is gradually making the successful treatment of infectious diseases more difficult. Antimicrobial peptides have been proposed as promising candidates for future drug development as they retain...... activity against bacteria resistant to conventional antibiotics and because resistance evolution is expected to be unlikely since the peptides have complex modes of action due to their interaction with the bacterial membrane. The work presented in this thesis has involved studies to increase our...

Development of SYN-004, an oral beta-lactamase treatment to protect the gut microbiome from antibiotic-mediated damage and prevent Clostridium difficile infection.

Science.gov (United States)

Kaleko, Michael; Bristol, J Andrew; Hubert, Steven; Parsley, Todd; Widmer, Giovanni; Tzipori, Saul; Subramanian, Poorani; Hasan, Nur; Koski, Perrti; Kokai-Kun, John; Sliman, Joseph; Jones, Annie; Connelly, Sheila

2016-10-01

The gut microbiome, composed of the microflora that inhabit the gastrointestinal tract and their genomes, make up a complex ecosystem that can be disrupted by antibiotic use. The ensuing dysbiosis is conducive to the emergence of opportunistic pathogens such as Clostridium difficile. A novel approach to protect the microbiome from antibiotic-mediated dysbiosis is the use of beta-lactamase enzymes to degrade residual antibiotics in the gastrointestinal tract before the microflora are harmed. Here we present the preclinical development and early clinical studies of the beta-lactamase enzymes, P3A, currently referred to as SYN-004, and its precursor, P1A. Both P1A and SYN-004 were designed as orally-delivered, non-systemically available therapeutics for use with intravenous beta-lactam antibiotics. SYN-004 was engineered from P1A, a beta-lactamase isolated from Bacillus licheniformis, to broaden its antibiotic degradation profile. SYN-004 efficiently hydrolyses penicillins and cephalosporins, the most widely used IV beta-lactam antibiotics. In animal studies, SYN-004 degraded ceftriaxone in the GI tract of dogs and protected the microbiome of pigs from ceftriaxone-induced changes. Phase I clinical studies demonstrated SYN-004 safety and tolerability. Phase 2 studies are in progress to assess the utility of SYN-004 for the prevention of antibiotic-associated diarrhea and Clostridium difficile disease. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

THE NEW METALL-BETA-LACTAMASE’S INHIBITOR EFFICACY IN A MODEL SYSTEM IN VITRO

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A. G. Afinogenova

2016-01-01

Full Text Available The Enterobacteriaceae antibiotics resistance depends on a combination of several mechanisms, such as the beta-lactamases overproduction, the microbial cell reduction outer membrane permeability (usually associated with loss of protein porin, the presence of efflux systems. Particularly noteworthy are the metallo-beta-lactamases (MBL whose presence causes resistance of gram-negative microorganisms to all beta-lactam antibiotics (in some cases except aztreonam. Currently there are no MBL inhibitors permitted for use in the clinic. The effective inhibitors search for carbapenem-resistant bacteria’ MBL authorized for use in the clinic and reinforcing effects of carbapenems, served as the basis for the present study. The work was carried out in three stages: 1 creating a model system using a standard enzyme reagent metallo-beta-lactamase P. aeruginosa recombinant expressed in E. coli, to evaluate the increasing of minimal inhibitory concentrations (MIC of carbapenems against previously sensitive Gram-negative microorganisms strains in vitro; 2 evaluation of MBL promising inhibitors in the presence of the same standard enzyme reagent; 3 evaluation of the ability of the identified inhibitors increase the carbapenems effects against clinical isolates of Gram-negative microorganisms producing MBL, in terms of the their MIC and fractional inhibitory concentration index (FIC index. The checkerboard array was modified to evaluate the combined use of carbapenems and potential MBL inhibitor — a drug from the group of bisphosphonates — etidronic acid. Using a standard enzyme reagent metallo-beta-lactamase P. aeruginosa recombinant expressed in E. coli, we created a model system that allows to assess the prospects of new inhibitors MBL gram-negative microorganisms. A dose-dependent effect of increasing the meropenem level MIC from reagent MBL quantity in a model system against previously antibiotic sensitive reference strains of microorganisms was

PEDIATRIC URINARY INFECTIONS, CAUSED BY EXTENDED-SPECTRUM BETA-LACTAMASE - PRODUCING MICROORGANISMS IN VARNA, BULGARIA

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Neli M. Ermenlieva

2016-05-01

Full Text Available Background: Extended-spectrum beta-lactamase (ESBLs producing bacteria are microorganisms which have the ability to hydrolyze β-lactame ring of a large part of the antibiotics, commonly used to treat bacterial infections including urinary tract infections. Purpose: The aim of this study is present the epidemiology of childhood urinary tract infections caused by ESBL-producing strains in Varna, Bulgaria. Material/methods: A total of 3895 urine samples of children patients (aged 0 to 18 years were examined during the period 2010-2012 for presence of ESBL-producing bacteria. Results: Six percent of the tested urinary samples were positive for ESBL production. All of the isolates were resistant to ampicillin, piperacillin, cephalothin, cefprozil, cefuroxime, ceftriaxone, ceftazidime, levofloxacin, cefaclor, but were were sensitive to meropenem and imipenem. Conclusions: Cephalosporins and penicillins are the most used antibiotics in Bulgaria, but they should be very precisely prescribed in medical practice, because otherwise preconditions for maintaining high share of ESBLs are created.

CDK2 phosphorylation of Smad2 disrupts TGF-beta transcriptional regulation in resistant primary bone marrow myeloma cells.

Science.gov (United States)

Baughn, Linda B; Di Liberto, Maurizio; Niesvizky, Ruben; Cho, Hearn J; Jayabalan, David; Lane, Joseph; Liu, Fang; Chen-Kiang, Selina

2009-02-15

Resistance to growth suppression by TGF-beta1 is common in cancer; however, mutations in this pathway are rare in hematopoietic malignancies. In multiple myeloma, a fatal cancer of plasma cells, malignant cells accumulate in the TGF-beta-rich bone marrow due to loss of both cell cycle and apoptotic controls. Herein we show that TGF-beta activates Smad2 but fails to induce cell cycle arrest or apoptosis in primary bone marrow myeloma and human myeloma cell lines due to its inability to activate G(1) cyclin-dependent kinase (CDK) inhibitors (p15(INK4b), p21(CIP1/WAF1), p27(KIP1), p57(KIP2)) or to repress c-myc and Bcl-2 transcription. Correlating with aberrant activation of CDKs, CDK-dependent phosphorylation of Smad2 on Thr(8) (pT8), a modification linked to impaired Smad activity, is elevated in primary bone marrow myeloma cells, even in asymptomatic monoclonal gammopathy of undetermined significance. Moreover, CDK2 is the predominant CDK that phosphorylates Smad2 on T8 in myeloma cells, leading to inhibition of Smad2-Smad4 association that precludes transcriptional regulation by Smad2. Our findings provide the first direct evidence that pT8 Smad2 couples dysregulation of CDK2 to TGF-beta resistance in primary cancer cells, and they suggest that disruption of Smad2 function by CDK2 phosphorylation acts as a mechanism for TGF-beta resistance in multiple myeloma.

Solventless Lactam Synthesis by Intramolecular Cyclizations of α-Iminoester Derivatives under Microwave Irradiation

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Aicha Derdour

2007-03-01

Full Text Available We have previously reported a new synthesis of amides from esters and amines under microwave irradiation, offering much higher yields than those achieved with conventional heating [1]. We have now extended these studies to the ring closure of neat iminoesters I2, I3 and I4-I6 to give five- and six-membered ring lactams L5, L6 and larger lactams L7-L9 (where I means imine and L means lactam, respectively, under both classical heating conditions and microwave irradiation.

Resistance to non-quinolone antimicrobials in commensal Escherichia coli isolates from chickens treated orally with enrofloxacin.

Science.gov (United States)

Jurado, Sonia; Medina, Alberto; de la Fuente, Ricardo; Ruiz-Santa-Quiteria, José A; Orden, José A

2015-11-01

The aim of the present study was evaluate how oral administration of enrofloxacin affected the frequency of resistance to different antimicrobials in commensal Escherichia coli isolates from healthy chickens. A further objective of this study was to characterize the mechanisms of resistance in these isolates. A trend towards increased resistance to enrofloxacin, doxycycline and amoxicillin of E. coli isolates from chickens after enrofloxacin administration was observed. The increase in the resistance to doxycycline and amoxicillin was probably due to a co-selection of tetracycline and β-lactam resistance genes by the administration of enrofloxacin. The detection of tetM was much higher than expected (50%), which indicates that this gene may play an important role in tetracycline resistance in E. coli from chickens.

Effects of inspiratory resistance, inhaled beta-agonists and histamine on canine tracheal blood flow

International Nuclear Information System (INIS)

Kelly, W.T.; Baile, E.M.; Brancatisano, A.; Pare, P.D.; Engel, L.A.

1992-01-01

Tracheobronchial blood flow is potentially important in asthma as it could either influence the clearance of mediators form the airways, thus affecting the duration and severity of bronchoispasm, or enhance oedema formation with a resultant increase in airflow obstruction. In anaesthetized dogs, spontaneously breathing via a tracheostomy, we investigated the effects of three interventions which are relevant to acute asthma attacks and could potentially influence blood flow and its distribution to the mucosa and remaining tissues of the trachea: 1) increased negative intrathoracic pressure swings (-25±1 cmH 2 O) induced by an inspiratory resistance; 2) variable inhaled doses of a beta-adrenoceptor-agonist (terbutaline); and 3) aerosolized histamine sufficient to produce a threefold increase in pulmonary resistance. Microspheres labelled with different radioisotopes were used to measure blood flow. Resistive breathing did not influence tracheobronchial blood flow. Following a large dose of terbutaline, mucosal blood flow (Qmb) increased by 50%. After inhaled histamine, Qmb reached 265% of the baseline value. We conclude that, whereas increased negative pressure swings do not influence tracheobronchial blood flow or its distribution, inhalation of aerosolized terbutaline, corresponding to a conventionally nebulized dose, increases mucosal blood flow. Our results also confirm that inhaled histamine, in a dose sufficient to produce moderate bronchoconstriction, increases tracheal mucosal blood flow in the area of deposition. (au)

Effects of inspiratory resistance, inhaled beta-agonists and histamine on canine tracheal blood flow

Energy Technology Data Exchange (ETDEWEB)

Kelly, W.T.; Baile, E.M.; Brancatisano, A.; Pare, P.D.; Engel, L.A. (Dept. of Respiratory Medicine, Westmead Hospital, Westmead, NSW (Australia))

1992-01-01

Tracheobronchial blood flow is potentially important in asthma as it could either influence the clearance of mediators form the airways, thus affecting the duration and severity of bronchoispasm, or enhance oedema formation with a resultant increase in airflow obstruction. In anaesthetized dogs, spontaneously breathing via a tracheostomy, we investigated the effects of three interventions which are relevant to acute asthma attacks and could potentially influence blood flow and its distribution to the mucosa and remaining tissues of the trachea: (1) increased negative intrathoracic pressure swings (-25[+-]1 cmH[sub 2]O) induced by an inspiratory resistance; (2) variable inhaled doses of a beta-adrenoceptor-agonist (terbutaline); and (3) aerosolized histamine sufficient to produce a threefold increase in pulmonary resistance. Microspheres labelled with different radioisotopes were used to measure blood flow. Resistive breathing did not influence tracheobronchial blood flow. Following a large dose of terbutaline, mucosal blood flow (Qmb) increased by 50%. After inhaled histamine, Qmb reached 265% of the baseline value. We conclude that, whereas increased negative pressure swings do not influence tracheobronchial blood flow or its distribution, inhalation of aerosolized terbutaline, corresponding to a conventionally nebulized dose, increases mucosal blood flow. Our results also confirm that inhaled histamine, in a dose sufficient to produce moderate bronchoconstriction, increases tracheal mucosal blood flow in the area of deposition. (au).

Central infusion of leptin improves insulin resistance and suppresses beta-cell function, but not beta-cell mass, primarily through the sympathetic nervous system in a type 2 diabetic rat model.

Science.gov (United States)

Park, Sunmin; Ahn, Il Sung; Kim, Da Sol

2010-06-05

We investigated whether hypothalamic leptin alters beta-cell function and mass directly via the sympathetic nervous system (SNS) or indirectly as the result of altered insulin resistant states. The 90% pancreatectomized male Sprague Dawley rats had sympathectomy into the pancreas by applying phenol into the descending aorta (SNSX) or its sham operation (Sham). Each group was divided into two sections, receiving either leptin at 300ng/kgbw/h or artificial cerebrospinal fluid (aCSF) via intracerebroventricular (ICV) infusion for 3h as a short-term study. After finishing the infusion study, ICV leptin (3mug/kg bw/day) or ICV aCSF (control) was infused in rats fed 30 energy % fat diets by osmotic pump for 4weeks. At the end of the long-term study, glucose-stimulated insulin secretion and islet morphometry were analyzed. Acute ICV leptin administration in Sham rats, but not in SNSX rats, suppressed the first- and second-phase insulin secretion at hyperglycemic clamp by about 48% compared to the control. Regardless of SNSX, the 4-week administration of ICV leptin improved glucose tolerance during oral glucose tolerance tests and insulin sensitivity at hyperglycemic clamp, compared to the control, while it suppressed second-phase insulin secretion in Sham rats but not in SNSX rats. However, the pancreatic beta-cell area and mass were not affected by leptin and SNSX, though ICV leptin decreased individual beta-cell size and concomitantly increased beta-cell apoptosis in Sham rats. Leptin directly decreases insulin secretion capacity mainly through the activation of SNS without modulating pancreatic beta-cell mass.

Detection of Extended-Spectrum Beta-Lactamase-Producing Escherichia coli in Market-Ready Chickens in Zambia.

Science.gov (United States)

Chishimba, K; Hang'ombe, B M; Muzandu, K; Mshana, S E; Matee, M I; Nakajima, C; Suzuki, Y

2016-01-01

The frequent administering of antibiotics in the treatment of poultry diseases may contribute to emergence of antimicrobial-resistant strains. The objective of this study was to detect the presence of extended-spectrum β-lactamase- (ESBL-) producing Escherichia coli in poultry in Zambia. A total of 384 poultry samples were collected and analyzed for ESBL-producing Escherichia coli. The cultured E. coli isolates were subjected to antimicrobial susceptibility tests and the polymerase chain reaction for detection of bla CTX-M, bla SHV, and bla TEM genes. Overall 20.1%, 77/384, (95% CI; 43.2-65.5%) of total samples analyzed contained ESBL-producing Escherichia coli. The antimicrobial sensitivity test revealed that 85.7% (66/77; CI: 75.7-92) of ESBL-producing E. coli isolates conferred resistance to beta-lactam and other antimicrobial agents. These results indicate that poultry is a potential reservoir for ESBL-producing Escherichia coli. The presence of ESBL-producing Escherichia coli in poultry destined for human consumption requires strengthening of the antibiotic administering policy. This is important as antibiotic administration in food animals is gaining momentum for improved animal productivity in developing countries such as Zambia.

Detection of Extended-Spectrum Beta-Lactamase-Producing Escherichia coli in Market-Ready Chickens in Zambia

Directory of Open Access Journals (Sweden)

K. Chishimba

2016-01-01

Full Text Available The frequent administering of antibiotics in the treatment of poultry diseases may contribute to emergence of antimicrobial-resistant strains. The objective of this study was to detect the presence of extended-spectrum β-lactamase- (ESBL- producing Escherichia coli in poultry in Zambia. A total of 384 poultry samples were collected and analyzed for ESBL-producing Escherichia coli. The cultured E. coli isolates were subjected to antimicrobial susceptibility tests and the polymerase chain reaction for detection of blaCTX-M, blaSHV, and blaTEM genes. Overall 20.1%, 77/384, (95% CI; 43.2–65.5% of total samples analyzed contained ESBL-producing Escherichia coli. The antimicrobial sensitivity test revealed that 85.7% (66/77; CI: 75.7–92 of ESBL-producing E. coli isolates conferred resistance to beta-lactam and other antimicrobial agents. These results indicate that poultry is a potential reservoir for ESBL-producing Escherichia coli. The presence of ESBL-producing Escherichia coli in poultry destined for human consumption requires strengthening of the antibiotic administering policy. This is important as antibiotic administration in food animals is gaining momentum for improved animal productivity in developing countries such as Zambia.

The bactericidal activity of β-lactam antibiotics is increased by metabolizable sugar species

DEFF Research Database (Denmark)

Thorsing, Mette; Bentin, Thomas; Givskov, Michael

2015-01-01

Here, the influence of metabolizable sugars on the susceptibility of Escherichia coli to β-lactam antibiotics was investigated. Notably, monitoring growth and survival of mono- and combination-treated planktonic cultures showed a 1000- to 10 000-fold higher antibacterial efficacy of carbenicillin...... and cefuroxime in the presence of certain sugars, whereas other metabolites had no effect on β-lactam sensitivity. This effect was unrelated to changes in growth rate. Light microscopy and flow cytometry profiling revealed that bacterial filaments, formed due to β-lactam-mediated inhibition of cell division......, rapidly appeared upon β-lactam mono-treatment and remained stable for up to 18 h. The presence of metabolizable sugars in the medium did not change the rate of filamentation, but led to lysis of the filaments within a few hours. No lysis occurred in E. coli mutants unable to metabolize the sugars, thus...

Isolation of methicillin-resistant Staphylococcus pseudintermedius from breeding dogs.

Science.gov (United States)

Rota, Ada; Milani, Chiara; Drigo, Ilenia; Drigo, Michele; Corrò, Michela

2011-01-01

The overuse of antimicrobials can select resistant bacteria strains; staphylococci have the ability to become resistant to all beta-lactam antimicrobials and are a significant concern in human medicine and a growing issue for veterinary medicine. Because antimicrobials are sometimes incorrectly used in breeding kennels, the objective of the work was to assess the occurrence of methicillin-resistant coagulase-positive staphylococci in breeding dogs. The research was carried out in 13 kennels that were allotted to three categories according to the intensity of antimicrobial use. Vaginal and milk swabs were taken from 87 healthy bitches around parturition and also from multiple organs of 27 of their pups that died within the first 2 weeks. Standard bacteriological examinations were carried out and coagulase-positive staphylococci were identified. All the coagulase-positive staphylococci resulted to be Staphylococcus pseudintermedius. Susceptibility to oxacillin and the presence of the mecA gene were tested. Nine out of 89 strains (six isolated from the bitches' milk and three from dead puppies, all belonging to kennels characterized by an excessive use of antimicrobials) were multidrug-resistant, methicillin-resistant and mecA positive. Our results confirm that excessive use of antimicrobials entails the risk of selecting resistant staphylococci strains. Our data also indicate that the bacterial flora of healthy dogs belonging to specific populations may act as a reservoir of resistance genes. Copyright © 2011 Elsevier Inc. All rights reserved.

lactamase in clinical isolates of Escherichia coli

African Journals Online (AJOL)

Jane

2011-08-22

Aug 22, 2011 ... The beta lactamase enzyme producing E. coli, resistant to β-lactam antibiotics, created many problems ... Key words: Escherichia coli, β-lactamase enzymes, TEM-type extended spectrum ... difficulties in treatment using antibiotics that are currently ... and chloramphenicol (30 µg) (Mast Diagnostics Ltd., UK).

[Resistance of gonococci in the Netherlands; results of a survey of medical microbiology laboratories].

Science.gov (United States)

van Loo, I H M; Spaargaren, J; van de Laar, M J W

2005-05-28

To collect information about the incidence ofgonorrhoea and gonococcal resistance in the Netherlands. A questionnaire was sent to 39 medical microbiology laboratories to obtain information on current diagnostics and the susceptibility testing method, and on the number of positive results and the susceptibility pattern of gonococcal isolates in 2002 and 2003 (up to and including November). 32 laboratories participated in this survey. 13 laboratories used culture alone and 19 laboratories used culture and/or a molecular test. Gonorrhoea was diagnosed 2,666 times in 2002 and 2,190 times in 2003, with an incidence of 33.5 and 27.0 per 100,000 inhabitants, respectively. The rate of resistance to beta-lactam antibiotics (penicillin and amoxicillin) was 12.2% and 10.7% in 2002 and 2003, respectively, and the rates of resistance to tetracycline were 18.5% and 20.6%. An increase in the resistance to quinolones was observed from 6.6% in 2002 to 9.5% in 2003. Resistance to cephalosporins was low (0.5% in 2002 and 1.2% in 2003). Furthermore, regional differences in susceptibility were found within the Netherlands. The observed gonococcal incidence and resistance form the basis for a gonorrhoea prevention and treatment programme in the Netherlands.

Methicillin-resistant Staphylococcus aureus containing mecC in Swedish dairy cows

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Unnerstad Helle Ericsson

2013-01-01

Full Text Available Abstract Background Hitherto, methicillin-resistant Staphylococcus aureus (MRSA has not been detected in Swedish cattle. However, due to the report of mecC, a novel homologue to the mecA gene, there was reason to re-evaluate susceptibility results from strain collections of Staphylococcus aureus and test suspected isolates for the presence of mecC. Findings Bovine isolates of S. aureus with elevated minimum inhibitory concentrations of beta-lactams were retrospectively tested for presence of mecC. In four of the isolates mecC was detected. Conclusion In Sweden, this is the first finding of MRSA in cattle and the first detection of MRSA harbouring mecC of domestic animal origin. MRSA in animal populations has implications as a potential reservoir with risk for spread to humans. Occurrence of MRSA among Swedish cattle appears still very limited.

Involvement of AmpG in mediating a dynamic relationship between serine beta-lactamase induction and biofilm-forming ability of Escherichia coli.

Science.gov (United States)

Mallik, Dhriti; Pal, Shilpa; Ghosh, Anindya S

2018-04-01

AmpG permease is implicated both in beta-lactamase induction and peptidoglycan recycling in enterobacterial isolates. Here, physiological studies using molecular genetics show that deletion of AmpG permease dramatically increases beta-lactam susceptibility even in the presence of AmpC, TEM-1 and OXA beta-lactamases. Also, there is an appreciable decrease in the biofilm-forming ability of strains lacking this protein. Expression of this permease in excess probably compromises the integrity of the bacterial cells, leading to cell lysis. Based on these results, we propose that AmpG permease may be used as a potential antibiotic target and its suppression could efficiently inhibit both beta-lactamase induction and biofilm formation.

Sublethal Ciprofloxacin Treatment Leads to Rapid Development of High-Level Ciprofloxacin Resistance during Long-Term Experimental Evolution of Pseudomonas aeruginosa

Science.gov (United States)

Jørgensen, Karin Meinike; Wassermann, Tina; Jensen, Peter Østrup; Hengzuang, Wang; Molin, Søren; Høiby, Niels

2013-01-01

The dynamics of occurrence and the genetic basis of ciprofloxacin resistance were studied in a long-term evolution experiment (940 generations) in wild-type, reference strain (PAO1) and hypermutable (PAOΔmutS and PAOMY-Mgm) P. aeruginosa populations continuously exposed to sub-MICs (1/4) of ciprofloxacin. A rapid occurrence of ciprofloxacin-resistant mutants (MIC of ≥12 μg/ml, representing 100 times the MIC of the original population) were observed in all ciprofloxacin-exposed lineages of PAOΔmutS and PAOMY-Mgm populations after 100 and 170 generations, respectively, and in one of the PAO1 lineages after 240 generations. The genetic basis of resistance was mutations in gyrA (C248T and G259T) and gyrB (C1397A). Cross-resistance to beta-lactam antibiotics was observed in the bacterial populations that evolved during exposure to sublethal concentrations of ciprofloxacin. Our study shows that mutants with high-level ciprofloxacin resistance are selected in P. aeruginosa bacterial populations exposed to sub-MICs of ciprofloxacin. This can have implications for the long-term persistence of resistant bacteria and spread of antibiotic resistance by exposure of commensal bacterial flora to low antibiotic concentrations. PMID:23774442

Treatment Modalities and Antimicrobial Stewardship Initiatives in the Management of Intra-Abdominal Infections

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Charles Hoffmann

2016-02-01

Full Text Available Antimicrobial stewardship programs (ASPs focus on improving the utilization of broad spectrum antibiotics to decrease the incidence of multidrug-resistant Gram positive and Gram negative pathogens. Hospital admission for both medical and surgical intra-abdominal infections (IAIs commonly results in the empiric use of broad spectrum antibiotics such as fluoroquinolones, beta-lactam beta-lactamase inhibitors, and carbapenems that can select for resistant organisms. This review will discuss the management of uncomplicated and complicated IAIs as well as highlight stewardship initiatives focusing on the proper use of broad spectrum antibiotics.

Synthesis of novel spiro-β-lactams

Indian Academy of Sciences (India)

Administrator

pathogenesis of Alzheimer's disease has also been shown to be coupled with cholesterol regulation. 4 ...... jected to dehalogenation studies. Treatment of these halospiro-β-lactams with n-Bu3SnH (1⋅2 equiv.) in the presence of catalytic amount of AIBN in reflux- ing benzene clearly afforded the dehalogenated product 13 ...

Enhancement of wear and corrosion resistance of beta titanium alloy by laser gas alloying with nitrogen

Science.gov (United States)

Chan, Chi-Wai; Lee, Seunghwan; Smith, Graham; Sarri, Gianluca; Ng, Chi-Ho; Sharba, Ahmed; Man, Hau-Chung

2016-03-01

The relatively high elastic modulus coupled with the presence of toxic vanadium (V) in Ti6Al4V alloy has long been a concern in orthopaedic applications. To solve the problem, a variety of non-toxic and low modulus beta-titanium (beta-Ti) alloys have been developed. Among the beta-Ti alloy family, the quaternary Ti-Nb-Zr-Ta (TNZT) alloys have received the highest attention as a promising replacement for Ti6Al4V due to their lower elastic modulus and outstanding long term stability against corrosion in biological environments. However, the inferior wear resistance of TNZT is still a problem that must be resolved before commercialising in the orthopaedic market. In this work, a newly developed laser surface treatment technique was employed to improve the surface properties of Ti-35.3Nb-7.3Zr-5.7Ta alloy. The surface structure and composition of the laser-treated TNZT surface were examined by grazing incidence X-ray diffraction (GI-XRD) and X-ray photoelectron spectroscopy (XPS). The wear and corrosion resistance were evaluated by pin-on-plate sliding test and anodic polarisation test in Hanks' solution. The experimental results were compared with the untreated (or base) TNZT material. The research findings showed that the laser surface treatment technique reported in this work can effectively improve the wear and corrosion resistance of TNZT.

Conversion of beta-methylbutyric acid to beta-hydroxy-beta-methylbutyric acid by Galactomyces reessii.

OpenAIRE

Lee, I Y; Nissen, S L; Rosazza, J P

1997-01-01

beta-Hydroxy-beta-methylbutyric acid (HMB) has been shown to increase strength and lean mass gains in humans undergoing resistance-exercise training. HMB is currently marketed as a calcium salt of HMB, and thus, environmentally sound and inexpensive methods of manufacture are being sought. This study investigates the microbial conversion of beta-methylbutyric acid (MBA) to HMB by cultures of Galactomyces reessii. Optimal concentrations of MBA were in the range of 5 to 20 g/liter for HMB produ...

Antibiotic resistance in Burkholderia species.

Science.gov (United States)

Rhodes, Katherine A; Schweizer, Herbert P

2016-09-01

The genus Burkholderia comprises metabolically diverse and adaptable Gram-negative bacteria, which thrive in often adversarial environments. A few members of the genus are prominent opportunistic pathogens. These include Burkholderia mallei and Burkholderia pseudomallei of the B. pseudomallei complex, which cause glanders and melioidosis, respectively. Burkholderia cenocepacia, Burkholderia multivorans, and Burkholderia vietnamiensis belong to the Burkholderia cepacia complex and affect mostly cystic fibrosis patients. Infections caused by these bacteria are difficult to treat because of significant antibiotic resistance. The first line of defense against antimicrobials in Burkholderia species is the outer membrane penetration barrier. Most Burkholderia contain a modified lipopolysaccharide that causes intrinsic polymyxin resistance. Contributing to reduced drug penetration are restrictive porin proteins. Efflux pumps of the resistance nodulation cell division family are major players in Burkholderia multidrug resistance. Third and fourth generation β-lactam antibiotics are seminal for treatment of Burkholderia infections, but therapeutic efficacy is compromised by expression of several β-lactamases and ceftazidime target mutations. Altered DNA gyrase and dihydrofolate reductase targets cause fluoroquinolone and trimethoprim resistance, respectively. Although antibiotic resistance hampers therapy of Burkholderia infections, the characterization of resistance mechanisms lags behind other non-enteric Gram-negative pathogens, especially ESKAPE bacteria such as Acinetobacter baumannii, Klebsiella pneumoniae and Pseudomonas aeruginosa. Copyright © 2016 Elsevier Ltd. All rights reserved.

Resistance to oral antibiotics in 4569 Gram-negative rods isolated from urinary tract infection in children.

Science.gov (United States)

Calzi, Anna; Grignolo, Sara; Caviglia, Ilaria; Calevo, Maria Grazia; Losurdo, Giuseppe; Piaggio, Giorgio; Bandettini, Roberto; Castagnola, Elio

2016-09-01

To investigate antibiotic resistance among pathogens isolated from urines in a tertiary care children's hospital in Italy. Retrospective analysis of prospectively collected data on antibiotic susceptibility of Gram-negatives isolated from urines at the Istituto Giannina Gaslini, Genoa - Italy from 2007 to 2014. Antibiotic susceptibility was evaluated. By means of CLSI criteria from 2007 to 2010, while from 2011 EUCAST criteria were adopted. Data on susceptibility to amoxicillin-clavulanate, co-trimoxazole, cefuroxime, nitrofurantoin, fosfomycin and ciprofloxacin were evaluated for Escherichia coli, while for other Enterobacteriaceae data were collected for amoxicillin-clavulanate, co-trimoxazole and ciprofloxacin and for ciprofloxacin against Pseudomonas aeruginosa. Univariate and multivariable analyses were performed for risk factors associated with resistance. A total of 4596 Gram-negative strains were observed in 3364 patients. A significant increase in the proportion of resistant strains was observed for E.coli against amoxicillin-clavulanate, cefuroxime and ciprofloxacin and for others Enterobacteriaceae against co-trimoxazole and ciprofloxacin. Resistance to nitrofurantoin and fosfomycin was very infrequent in E.coli. Logistic regression analysis showed that repeated episode of urinary tract infections was a risk factor for E.coli resistance to amoxicillin-clavulanate, co-trimoxazole and cefuroxime, while admission in one of the Units usually managing children with urinary tract malformations was significantly associated to resistance to amoxicillin-clavulanate and cefuroxime. In conclusion the present study shows an increase in antibiotic resistance in pediatric bacteria isolated from urines in children, especially in presence of repeated episodes and/or urinary tract malformations. This resistance is worrisome for beta-lactams and cotrimoxazole, and start to increase also for fluoroquinolones while nitrofurantoin and fosfomycin still could represent useful

Diversity and antibiotic resistance patterns of Sphingomonadaceae isolates from drinking water.

Science.gov (United States)

Vaz-Moreira, Ivone; Nunes, Olga C; Manaia, Célia M

2011-08-15

Sphingomonadaceae (n = 86) were isolated from a drinking water treatment plant (n = 6), tap water (n = 55), cup fillers for dental chairs (n = 21), and a water demineralization filter (n = 4). The bacterial isolates were identified based on analysis of the 16S rRNA gene sequence, and intraspecies variation was assessed on the basis of atpD gene sequence analysis. The isolates were identified as members of the genera Sphingomonas (n = 27), Sphingobium (n = 28), Novosphingobium (n = 12), Sphingopyxis (n = 7), and Blastomonas (n = 12). The patterns of susceptibility to five classes of antibiotics were analyzed and compared for the different sites of isolation and taxonomic groups. Colistin resistance was observed to be intrinsic (92%). The highest antibiotic resistance prevalence values were observed in members of the genera Sphingomonas and Sphingobium and for beta-lactams, ciprofloxacin, and cotrimoxazole. In tap water and in water from dental chairs, antibiotic resistance was more prevalent than in the other samples, mainly due to the predominance of isolates of the genera Sphingomonas and Sphingobium. These two genera presented distinct patterns of association with antibiotic resistance, suggesting different paths of resistance development. Antibiotic resistance patterns were often related to the species rather than to the site or strain, suggesting the importance of vertical resistance transmission in these bacteria. This is the first study demonstrating that members of the family Sphingomonadaceae are potential reservoirs of antibiotic resistance in drinking water.

Diversity and Antibiotic Resistance Patterns of Sphingomonadaceae Isolates from Drinking Water▿

Science.gov (United States)

Vaz-Moreira, Ivone; Nunes, Olga C.; Manaia, Célia M.

2011-01-01

Sphingomonadaceae (n = 86) were isolated from a drinking water treatment plant (n = 6), tap water (n = 55), cup fillers for dental chairs (n = 21), and a water demineralization filter (n = 4). The bacterial isolates were identified based on analysis of the 16S rRNA gene sequence, and intraspecies variation was assessed on the basis of atpD gene sequence analysis. The isolates were identified as members of the genera Sphingomonas (n = 27), Sphingobium (n = 28), Novosphingobium (n = 12), Sphingopyxis (n = 7), and Blastomonas (n = 12). The patterns of susceptibility to five classes of antibiotics were analyzed and compared for the different sites of isolation and taxonomic groups. Colistin resistance was observed to be intrinsic (92%). The highest antibiotic resistance prevalence values were observed in members of the genera Sphingomonas and Sphingobium and for beta-lactams, ciprofloxacin, and cotrimoxazole. In tap water and in water from dental chairs, antibiotic resistance was more prevalent than in the other samples, mainly due to the predominance of isolates of the genera Sphingomonas and Sphingobium. These two genera presented distinct patterns of association with antibiotic resistance, suggesting different paths of resistance development. Antibiotic resistance patterns were often related to the species rather than to the site or strain, suggesting the importance of vertical resistance transmission in these bacteria. This is the first study demonstrating that members of the family Sphingomonadaceae are potential reservoirs of antibiotic resistance in drinking water. PMID:21705522

Epidemiology and resistance patterns in urinary pathogens from long-term care facilities and GP populations.

LENUS (Irish Health Repository)

Brabazon, E D

2012-06-01

Urinary tract infections (UTIs) are a major source of antimicrobial prescribing in the clinical setting and a potential reservoir for the emergence of resistant organisms. Although studies have been published on resistance rates for urinary pathogens from both hospital and general practitioner (GP) settings, there is little information from Long-Term Care Facilities (LTCFs) in Ireland. This study aimed to document the epidemiology and resistance rates in urinary isolates, in the LTCF and GP setting, from samples submitted to a typical microbiology laboratory. In 2010, there were 963 urinary isolates from LTCFs and 1,169 urinary isolates from GPs, identified from patients 65 years and over, with cytology suggestive of infection. E. coil was the most common causative organism identified. There were significantly higher levels of resistance to ampicillin, co-amoxiclav, ciprofloxacin, nitrofurantoin, trimethoprim, and piperacillin\\/tazobactam in the LTCF population compared to the GP population (e.g. for E. coli, 86%-v-69%; 30%-v- 21%; 58%-v-26%, 10%-v-3%, 68%-v-48%, 10%-v- 4% respectively). Isolates with resistance mechanisms to beta-lactams, were identified in both populations. Results presented in this paper demonstrate significant differences between resistance rates in LTCF and GP populations which suggest that there are implications for empiric antimicrobial prescribing for UTIs in the LTCF setting.

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

Science.gov (United States)

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

Application of Nanoparticle Technology to Reduce the Anti-Microbial Resistance through β-Lactam Antibiotic-Polymer Inclusion Nano-Complex.

Science.gov (United States)

Salamanca, Constain H; Yarce, Cristhian J; Roman, Yony; Davalos, Andrés F; Rivera, Gustavo R

2018-02-10

Biocompatible polymeric materials with potential to form functional structures in association with different therapeutic molecules have a high potential for biological, medical and pharmaceutical applications. Therefore, the capability of the inclusion of nano-Complex formed between the sodium salt of poly(maleic acid- alt -octadecene) and a β-lactam drug (ampicillin trihydrate) to avoid the chemical and enzymatic degradation and enhance the biological activity were evaluated. PAM-18Na was produced and characterized, as reported previously. The formation of polymeric hydrophobic aggregates in aqueous solution was determined, using pyrene as a fluorescent probe. Furthermore, the formation of polymer-drug nano-complexes was characterized by Differential Scanning Calorimetry-DSC, viscometric, ultrafiltration/centrifugation assays, zeta potential and size measurements were determined by dynamic light scattering-DLS. The PAM-18Na capacity to avoid the chemical degradation was studied through stress stability tests. The enzymatic degradation was evaluated from a pure β-lactamase, while the biological degradation was determined by different β-lactamase producing Staphylococcus aureus strains. When ampicillin was associated with PAM-18Na, the half-life time in acidic conditions increased, whereas both the enzymatic degradation and the minimum inhibitory concentration decreased to a 90 and 75%, respectively. These results suggest a promissory capability of this polymer to protect the β-lactam drugs against chemical, enzymatic and biological degradation.

Population Genomic Analysis of 1,777 Extended-Spectrum Beta-Lactamase-Producing Klebsiella pneumoniae Isolates, Houston, Texas: Unexpected Abundance of Clonal Group 307.

Science.gov (United States)

Long, S Wesley; Olsen, Randall J; Eagar, Todd N; Beres, Stephen B; Zhao, Picheng; Davis, James J; Brettin, Thomas; Xia, Fangfang; Musser, James M

2017-05-16

Klebsiella pneumoniae is a major human pathogen responsible for high morbidity and mortality rates. The emergence and spread of strains resistant to multiple antimicrobial agents and documented large nosocomial outbreaks are especially concerning. To develop new therapeutic strategies for K. pneumoniae , it is imperative to understand the population genomic structure of strains causing human infections. To address this knowledge gap, we sequenced the genomes of 1,777 extended-spectrum beta-lactamase-producing K. pneumoniae strains cultured from patients in the 2,000-bed Houston Methodist Hospital system between September 2011 and May 2015, representing a comprehensive, population-based strain sample. Strains of largely uncharacterized clonal group 307 (CG307) caused more infections than those of well-studied epidemic CG258. Strains varied markedly in gene content and had an extensive array of small and very large plasmids, often containing antimicrobial resistance genes. Some patients with multiple strains cultured over time were infected with genetically distinct clones. We identified 15 strains expressing the New Delhi metallo-beta-lactamase 1 (NDM-1) enzyme that confers broad resistance to nearly all beta-lactam antibiotics. Transcriptome sequencing analysis of 10 phylogenetically diverse strains showed that the global transcriptome of each strain was unique and highly variable. Experimental mouse infection provided new information about immunological parameters of host-pathogen interaction. We exploited the large data set to develop whole-genome sequence-based classifiers that accurately predict clinical antimicrobial resistance for 12 of the 16 antibiotics tested. We conclude that analysis of large, comprehensive, population-based strain samples can assist understanding of the molecular diversity of these organisms and contribute to enhanced translational research. IMPORTANCE Klebsiella pneumoniae causes human infections that are increasingly difficult to

Fighting infections due to multidrug-resistant Gram-positive pathogens.

Science.gov (United States)

Cornaglia, G

2009-03-01

Growing bacterial resistance in Gram-positive pathogens means that what were once effective and inexpensive treatments for infections caused by these bacteria are now being seriously questioned, including penicillin and macrolides for use against pneumococcal infections and-in hospitals-oxacillin for use against staphylococcal infections. As a whole, multidrug-resistant (MDR) Gram-positive pathogens are rapidly becoming an urgent and sometimes unmanageable clinical problem. Nevertheless, and despite decades of research into the effects of antibiotics, the actual risk posed to human health by antibiotic resistance has been poorly defined; the lack of reliable data concerning the outcomes resulting from antimicrobial resistance stems, in part, from problems with study designs and the methods used in resistence determination. Surprisingly little is known, too, about the actual effectiveness of the many types of intervention aimed at controlling antibiotic resistance. New antibiotics active against MDR Gram-positive pathogens have been recently introduced into clinical practice, and the antibiotic pipeline contains additional compounds at an advanced stage of development, including new glycopeptides, new anti-methicillin-resistant Staphylococcus aureus (MRSA) beta-lactams, and new diaminopyrimidines. Many novel antimicrobial agents are likely to be niche products, endowed with narrow antibacterial spectra and/or targeted at specific clinical problems. Therefore, an important educational goal will be to change the current, long-lasting attitudes of both physicians and customers towards broad-spectrum and multipurpose compounds. Scientific societies, such as the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), must play a leading role in this process.

Insulin resistance and beta-cell function in different ethnic groups in Kenya: the role of abdominal fat distribution

DEFF Research Database (Denmark)

Christensen, D.L.; Faurholt-Jepsen, D.; Faerch, K.

2014-01-01

Little is known about the pathophysiology of diabetes in Africans. Thus, we assessed whether insulin resistance and beta-cell function differed by ethnicity in Kenya and whether differences were modified by abdominal fat distribution. A cross-sectional study in 1,087 rural Luo (n = 361), Kamba (n...... to the Luo and Kamba, respectively. Adjustments of SAT (range 0.1–7.1 cm) and VAT (range 1.5–14.2 cm) largely explained these inter-group differences with the Maasai having the highest combined abdominal fat accumulation. The Maasai had the highest insulin resistance and secretion, but the lowest relative...... beta-cell function compared to the Luo and Kamba. These differences were primarily explained by abdominal fat distribution....

Allostery, Recognition of Nascent Peptidoglycan, and Cross-linking of the Cell Wall by the Essential Penicillin-Binding Protein 2x of Streptococcus pneumoniae

Czech Academy of Sciences Publication Activity Database

Bernardo-Garcia, N.; Mahasenan, K.V.; Batuecas, M.T.; Lee, M.; Hesek, D.; Petráčková, Denisa; Doubravová, Linda; Branny, Pavel; Mobashery, S.; Hermoso, J. A.

2018-01-01

Roč. 13, č. 3 (2018), s. 694-702 ISSN 1554-8929 R&D Projects: GA ČR GAP207/12/1568 Institutional support: RVO:61388971 Keywords : RESISTANT STAPHYLOCOCCUS-AUREUS * BETA-LACTAM-BINDING * KINASE STKP Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 4.995, year: 2016

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

DEFF Research Database (Denmark)

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....

Acquisition and clearance of multidrug resistant Acinetobacter baumannii on healthy young adults concurrently burned in a dust explosion in Taiwan: the implication for antimicrobial stewardship.

Science.gov (United States)

Huang, Po-Yen; Shie, Shian-Sen; Ye, Jung-Jr; Lin, Shih-Pin; Liu, Tsui-Ping; Wu, Ting-Shu; Wu, Tsu-Lan; Chuang, Shiow-Shuh; Cheng, Ming-Huei; Hsieh, Yu-Chia; Huang, Ching-Tai

2017-08-30

Information is limited about the effect of restricted carbapenem use on clearance of multi-drug resistant Acinetobacter baumannii (MDRAB). We sought to determine the time effect of antibiotic exposure on multi-drug resistant Acinetobacter baumannii (MDRAB) acquisition and clearance. We conducted a retrospective observational study at the intensive care units of a tertiary medical center. Forty-two of a cohort of previously healthy young adults who were concurrently burned by a dust explosion was included. Cases consisted of those from whom MDRAB was isolated during hospitalization. Controls consisted of patients from whom MDRAB was not isolated in the same period. Use of antimicrobial agents was compared based on days of therapy per 1,000 patient-days (DOT/1,000PD). A 2-state Markov multi-state model was used to estimate the risk of acquisition and clearance of MDRAB. MDRAB was discovered in 9/42 (21.4%) individuals. The cases had significantly higher use of carbapenem (652 DOT/1,000PD vs. 385 DOT/1,000PD, P < 0.001) before MDRAB isolation. For the cases, clearance of MDRAB was associated with lower use of carbapenem (469 DOT/1,000PD vs. 708 DOT/1,000PD, P = 0.003) and higher use of non-carbapenem beta-lactam (612 DOT/1,000PD vs. 246 DOT/1,000PD, P <0.001). In multi-state model, each additional DOT of carbapenem increased the hazard of acquiring MDRAB (hazard ratio (HR), 1.08; 95% confidence interval (CI) 1.01-1.16) and each additional DOT of non-carbapenem beta-lactam increased the protection of clearing MDRAB (HR, 1.25; 95% CI 1.07-1.46). Both acquisition and clearance of MDRAB were related to antibiotic exposure in a homogeneous population. Our findings suggest that early discontinuation of carbapenem could be an effective measure in antibiotic stewardship for the control of MDRAB spreading.

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.

Science.gov (United States)

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

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 Å 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. IMPORTANCE Antibiotic resistance is emerging at unprecedented rates and threatens to reach crisis levels. One key

Subtleties in practical application of prolonged infusion of β-lactam antibiotics.

Science.gov (United States)

De Waele, Jan J; Lipman, Jeffrey; Carlier, Mieke; Roberts, Jason A

2015-05-01

Prolonged infusion (PI) of β-lactam antibiotics is increasingly used in order to optimise antibiotic exposure in critically ill patients. Physicians are often not aware of a number of subtleties that may jeopardise the treatment. In this clinically based paper, we stress pragmatic issues, such as the importance of a loading dose before PI, and discuss a number of important practicalities that are mandatory to benefit from the pharmacokinetic advantages of prolonged β-lactam antibiotic administration. Copyright © 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Multidrug Resistance in Infants and Children

Directory of Open Access Journals (Sweden)

Gian Maria Pacifici

2018-02-01

Full Text Available Bacterial infections may cause disease and death. Infants and children are often subject to bacterial infections. Antimicrobials kill bacteria protecting the infected patients andreducing the risk of morbidity and mortality caused by bacteria. The antibiotics may lose their antibacterial activity when they become resistant to a bacteria. The resistance to different antibiotics in a bacteria is named multidrug-resistance. Gram-negative bacilli, especially Escherichia coli, Klebsiella, Enterobacter, Salmonella, Shigella, Pseudomonas, Streptococcus, and Haemophilus influenzae type b, may become resistant. Amikacin ampicillin, amoxicillin, amoxiclav, cefuroxime, cefotaxime, ceftazidime, cefoperazone tetracycline, chloramphenicol, ciprofloxacin, and gentamicin may cause bacterial-resistance. Resistance to bacteria for several pathogens makes complications in the treatment of infections caused by them. Salmonella strains may become resistant to ampicillin, cephalotin, ceftriaxone, gentamicin, amikacin, trimethoprim-sulfamethoxazole, chloramphenicol, and tetracycline. Shigella strains may become resistant to ampicillin, cotrimoxazole, chloramphenicol, and streptomycin. Multidrug-resistance of Streptococcus pneumoniae may be due to β-lactams, macrolides, tetracycline, chloramphenicol, and trimethoprim-sulfamethoxazole. Multidrug-resistance of Pseudomonas aeruginosa may become resistant to β-lactams, chloramphenicol, trimethoprim-sulfamethoxazole, and tetracycline. The antibacterial activity against Haemophilus strains may occur with ampicillin, sulbactam-ampicillin, trimethoprim-sulfamethoxazole, gentamicin, chloramphenicol, and ciprofloxacin. Multidrug-resistance of the Klebsiella species may be due with ampicillin, cefotaxime, cefuroxime, co-amxilav, mezlocillin, chloramphenicol, gentamicin, and ceftazidime. Multidrug-resistance of Escherichia coli may be caused by ampicillin, cotrimoxazole, chloramphenicol, ceftriaxone, and ceftazidime. Vibrio

Enhancement of wear and corrosion resistance of beta titanium alloy by laser gas alloying with nitrogen

International Nuclear Information System (INIS)

Chan, Chi-Wai; Lee, Seunghwan; Smith, Graham; Sarri, Gianluca; Ng, Chi-Ho; Sharba, Ahmed; Man, Hau-Chung

2016-01-01

Graphical abstract: - Highlights: • Laser technology is a fast, clean and flexible method for surface hardening of TNZT. • Laser can form a protective hard layer on TNZT surface without altering surface roughness. • The laser-formed layer is metallurgically bonded to the substrate. • Laser-treated TNZT is highly resistant to corrosion and wear in Hank's solution. - Abstract: The relatively high elastic modulus coupled with the presence of toxic vanadium (V) in Ti6Al4V alloy has long been a concern in orthopaedic applications. To solve the problem, a variety of non-toxic and low modulus beta-titanium (beta-Ti) alloys have been developed. Among the beta-Ti alloy family, the quaternary Ti–Nb–Zr–Ta (TNZT) alloys have received the highest attention as a promising replacement for Ti6Al4V due to their lower elastic modulus and outstanding long term stability against corrosion in biological environments. However, the inferior wear resistance of TNZT is still a problem that must be resolved before commercialising in the orthopaedic market. In this work, a newly developed laser surface treatment technique was employed to improve the surface properties of Ti–35.3Nb–7.3Zr–5.7Ta alloy. The surface structure and composition of the laser-treated TNZT surface were examined by grazing incidence X-ray diffraction (GI-XRD) and X-ray photoelectron spectroscopy (XPS). The wear and corrosion resistance were evaluated by pin-on-plate sliding test and anodic polarisation test in Hanks’ solution. The experimental results were compared with the untreated (or base) TNZT material. The research findings showed that the laser surface treatment technique reported in this work can effectively improve the wear and corrosion resistance of TNZT.

Frequency of resistance to penicillin and erythromycin of pneumococcal strains that caused ottis media

Directory of Open Access Journals (Sweden)

Jovanović Luka

2017-01-01

Full Text Available Introduction: Streptococcus pneumoniae is an important human pathogen and the most common cause of acute otitis media (AOM, especially in children. It is also a common cause of community acquired pneumonia, sepsis and bacterial meningitis. Drug of choice in the treatment of these disease are beta lactam antibiotics, and the first alternative are macrolides. The increasing prevalence of resistance to penicillin and macrolides, among pneumococci, has considerably complicated the treatment. Aim: The aim of this study was to determine susceptibility of pneumococcal isolates from pediatric AOM in Serbia to antibiotics. Material and methods: Antimicrobial susceptibility testing of 61 pneumococcal AOM was performed, collected from December 2014 to December 2015, using disk diffusion method and E test. Macrolide resistance profile was determined by double disk diffusion test. Results: In our study, 40 strains (65.6% showed reduced sensitivity to penicillin and erythromycin. There were 9 (14.8% high resistant isolates to penicillin, while 31 (50.8% showed reduced susceptibility. The most frequent resistance phenotype was cMLS. Co-resistance to penicillin and macrolides was found in 14.8% strains. Conclusion: Our results showed high resistance rate of S. pneumoniae, which causes AOM among children, to penicillin and macrolides. Further active surveillance of pneumococcal susceptibility to antibiotics is necessary, and use of these medications in empirical therapy should be limited.

Recent independent emergence of multiple multidrug-resistant Serratia marcescens clones within the United Kingdom and Ireland.

Science.gov (United States)

Moradigaravand, Danesh; Boinett, Christine J; Martin, Veronique; Peacock, Sharon J; Parkhill, Julian

2016-08-01

Serratia marcescens, a member of the Enterobacteriaceae family, is a Gram-negative bacterium responsible for a wide range of nosocomial infections. The emergence of multidrug-resistant strains is an increasing danger to public health. To design effective means to control the dissemination of S. marcescens, an in-depth analysis of the population structure and variation is required. Utilizing whole-genome sequencing, we characterized the population structure and variation, as well as the antimicrobial resistance determinants, of a systematic collection of antimicrobial-resistant S. marcescens associated with bloodstream infections in hospitals across the United Kingdom and Ireland between 2001 and 2011. Our results show that S. marcescens is a diverse species with a high level of genomic variation. However, the collection was largely composed of a limited number of clones that emerged from this diverse background within the past few decades. We identified potential recent transmissions of these clones, within and between hospitals, and showed that they have acquired antimicrobial resistance determinants for different beta-lactams, ciprofloxacin, and tetracyclines on multiple occasions. The expansion of these multidrug-resistant clones suggests that the treatment of S. marcescens infections will become increasingly difficult in the future. © 2016 Moradigaravand et al.; Published by Cold Spring Harbor Laboratory Press.

Effect of beta-adrenergic blockade on elevated arterial compliance and low systemic vascular resistance in cirrhosis

DEFF Research Database (Denmark)

Møller, Søren; Bendtsen, Flemming; Henriksen, Jens Henrik

2001-01-01

with beta-blockers, but the effect of this treatment on arterial compliance has not been investigated. The aim of the present study was therefore to assess the effects of propranolol on the arterial compliance of patients with cirrhosis. METHODS: Twenty patients with cirrhosis underwent a haemodynamic......) of 17.8 mmHg, and responded to beta-blocker treatment with a significant reduction in the HVPG (-16%; P beta-adrenergic blockade (1.27 versus 1.29 ml/mmHg, +2%, ns), whereas...... with beta-blockers increases small vessel (arteriolar) vascular tone towards the normal level, but does not affect the elevated compliance of the larger arteries in patients with cirrhosis....

Environmental cycle of antibiotic resistance encoded genes: A systematic review

Directory of Open Access Journals (Sweden)

R. ghanbari

2017-12-01

Full Text Available Antibiotic-resistant bacteria and genes enter the environment in different ways. The release of these factors into the environment has increased concerns related to public health. The aim of the study was to evaluate the antibiotic resistance genes (ARGs in the environmental resources. In this systematic review, the data were extracted from valid sources of information including ScienceDirect, PubMed, Google Scholar and SID. Evaluation and selection of articles were conducted on the basis of the PRISMA checklist. A total of 39 articles were included in the study, which were chosen from a total of 1249 papers. The inclusion criterion was the identification of genes encoding antibiotic resistance against the eight important groups of antibiotics determined by using the PCR technique in the environmental sources including municipal and hospital wastewater treatment plants, animal and agricultural wastes, effluents from treatment plants, natural waters, sediments, and drinking waters. In this study, 113 genes encoding antibiotic resistance to eight groups of antibiotics (beta-lactams, aminoglycosides, tetracyclines, macrolides, sulfonamides, chloramphenicol, glycopeptides and quinolones were identified in various environments. Antibiotic resistance genes were found in all the investigated environments. The investigation of microorganisms carrying these genes shows that most of the bacteria especially gram-negative bacteria are effective in the acquisition and the dissemination of these pollutants in the environment. Discharging the raw wastewaters and effluents from wastewater treatments acts as major routes in the dissemination of ARGs into environment sources and can pose hazards to public health.

Trends in Drug Resistance of Acinetobacter baumannii over a 10-year Period: Nationwide Data from the China Surveillance of Antimicrobial Resistance Program.

Science.gov (United States)

Gao, Lei; Lyu, Yuan; Li, Yun

2017-03-20

Acinetobacter baumannii has emerged as an important pathogen causing a variety of infections. Using data from the China Surveillance of Antimicrobial Resistance Program conducted biennially, we investigated the secular changes in the resistance of 2917 isolates of A. baumannii from 2004 to 2014 to differ antimicrobial agents. Pathogen samples were collected from 17 to 20 hospitals located in the eastern, central, and western regions of China. Minimum inhibitory concentrations (MICs) were determined by a 2-fold agar dilution method, and antimicrobial susceptibility was established using the 2014 Clinical Laboratory Standards Institute-approved breakpoints. Isolates not susceptible to all the tested aminoglycosides, fluoroquinolones, β-lactams, β-lactam/β-lactam inhibitors and carbapenems were defined as extensively drug resistant. The rates of nonsusceptibility to common antimicrobial agents remained high (>65%) over the years with some fluctuations to certain agents. The prevalence of imipenem-resistant A. baumannii (IRAB) increased from 13.3% in 2004 to 70.5% in 2014 and that of extensively drug-resistant A. baumannii (XDRAB) increased from 11.1% in 2004 to 60.4% in 2014. The activity of tigecycline was stable with MIC90 ≤4 mg/L against A. baumannii from 2009 to 2014. Susceptibility to colistin remained high (97.0%) from 2009 to 2014. The prevalence of XDRAB increased in all the three surveillance regions over the years and was significantly higher in Intensive Care Unit (ICU) wards than non-ICU wards. This longitudinal multicenter surveillance program revealed the nationwide emergence of A. baumannii in China and showed a significant increase in prevalence from 2004 to 2014. High levels of bacterial resistance were detected among samples collected from clinical settings in China, with IRAB and XDRAB being especially prevalent. This study will help to guide empirical therapy and identify at-risk groups requiring more intense interventional infection control

Treatment and prevention of invasive pneumococcal disease.

Science.gov (United States)

Domínguez-Alegría, A R; Pintado, V; Barbolla, I

2018-02-12

Invasive pneumococcal disease is a severe infection that mainly affects patients with associated comorbidity. The paediatric conjugate vaccination has resulted in a change in the adult vaccination strategy. The antibiotic resistance of pneumococcus is not currently a severe problem. Nevertheless, the World Health Organisation has included pneumococcus among the bacteria whose treatment requires the introduction of new drugs, such as ceftaroline and ceftobiprole. Although the scientific evidence is still limited, the combination of beta-lactams and macrolides is recommended as empiric therapy for bacteraemic pneumococcal pneumonia. Copyright © 2018 Elsevier España, S.L.U. and Sociedad Española de Medicina Interna (SEMI). All rights reserved.

Beta4 integrin-dependent formation of polarized three-dimensionalarchitecture confers resistance to apoptosis in normal and malignantmammary epithelium

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Weaver, Valerie M.; Lelievre, Sophie; Lakins, Johnathon N.; Chrenek, Micah A.; Jones, Jonathan C.R.; Giancotti, Filippo; Werb, Zena; Bissell, Mina J.

2002-08-27

Tumor cells can evade chemotherapy by acquiring resistanceto apoptosis. We investigated the molecular mechanism whereby malignantand nonmalignant mammary epithelial cells become insensitive toapoptosis. We show that regardless of growth status formation ofpolarized, three-dimensional structures driven by basement membraneconfers protection to apoptosis in both nonmalignant and malignantmammary epithelial cells. By contrast, irrespective of their malignantstatus, nonpolarized structures are sensitive to induction of apoptosis.Resistance to apoptosis requires ligation of beta4 integrins, whichregulates tissue polarity, hemidesmosome formation and NFkB activation.Expression of beta4 integrin that lacks the hemidesmosome targetingdomain interferes with tissue polarity and NFkB activation and permitsapoptosis. These results indicate that integrin-induced polarity maydrive tumor cell resistance to apoptosis-inducing agents via effects onNFkB.

Pituitary resistance to thyroid hormone associated with a base mutation in the hormone-binding domain of the human 3, 5,3[prime]-triiodothyronine receptor-[beta

Energy Technology Data Exchange (ETDEWEB)

Sasaki, Shigekazu; Nakamura, Hirotoshi; Tagami, Tetsuya; Miyoshi, Yohzi; Nogimori, Tsuyoshi; Mitsuma, Terunori; Imura, Hiroo (Kyoto Univ. School of Medicine, Aichi (Japan))

1993-05-01

Point mutations in the human T[sub 3] receptor-[beta] (TR[beta]) gene causing single amino acid substitutions have been identified in several different kindred with generalized resistance to thyroid hormone. Until now, no study has been reported on the TR gene in cases of pituitary resistance (PRTH). In the present study, the authors analyzed the TR[beta] gene in a 30-yr-old Japanese female with PRTH. She exhibited clinical features of hyperthyroidism, elevated serum thyroid hormone levels accompanied by inappropriately increased secretion of TSH, mildly elevated basal metabolic rate, and increased urinary excretion of hydroxyproline. No pituitary tumor was detected. DNA fragments of exons 3-8 of the geonomic TR[beta] gene were generated by the polymerase chain reaction and analyzed by a single stranded conformation polymorphism method. Exon 7 of the patient's TR[beta] gene showed an abnormal band, suggesting the existence of mutation(s). By subcloning and sequencing the DNA, a point mutation was identified in one allele at nucleotide 1297 (C to T), which altered the 333rd amino acid, arginine, to tryptophan. Neither of her apparently normal parents had any mutations of the TR[beta] gene. In vitro translation products of the mutant TR[beta] gene showed remarkably decreased T[sub 3]-binding activity (K[sub a], 2.1 [times] 10[sup 8] M[sup [minus]1]; normal TR[beta] K[sub a], 1.1 [times] 10[sup 10] M[sup [minus]1]). Since the molecular defect detected in a patient with PRTH is similar to that seen in subjects with generalized resistance to thyroid hormone, both types of the syndrome may represent a continuous spectrum of the same etiological defect with variable tissue resistance to thyroid hormone.

beta-Lactamases among extended-spectrum beta-lactamase (ESBL)-resistant Salmonella from poultry, poultry products and human patients in The Netherlands

DEFF Research Database (Denmark)

Hasman, Henrik; Mevius, D.; Veldman, K.

2005-01-01

Objectives: The purpose of this work was to study the genetic determinants responsible for extended-spectrum beta-lactamase (ESBL) resistance of Salmonella isolated from Dutch poultry, poultry meat and hospitalized humans. Methods: Thirty-four ESBL-resistant Salmonella isolates from The Netherlands...... were tested towards 21 antimicrobial agents. PCR and sequencing were used to determine the underlying genetic determinants responsible for the ESBL phenotypes. The transferability of the ESBL phenotypes was tested by conjugation to a susceptible Salmonella enterica serovar Dublin and plasmid....... Finally, the bla(ACC-1) gene was cloned from a S. Bareilly isolate and was found to be present on indistinguishable plasmids in all S. Bareilly isolates examined as well as in a S. Braenderup isolate and a S. Infantis isolate. Conclusions: Our data underscore the diversity of ESBL genes in Salmonella...

Synthesis of substituted gamma-lactams through petasis-type addition of boronic acids to N-acyliminium lons

DEFF Research Database (Denmark)

Wu, Peng; Clausen, Mads Hartvig; Nielsen, Thomas Eiland

2014-01-01

Substituted g -lactams are important heterocyclic motifs found in various biologically active compounds and marketed drugs, such as glimepiride, doxapram, and levetiracetam. Among available m ethods for the synthesis of substituted g -lactams, the addition of nucleophiles to N -acyliminium ions...

Effect of long-term transfusion therapy on the glycometabolic status and pancreatic beta cell function in patients with beta Thalassemia major

Directory of Open Access Journals (Sweden)

Kamalakshi G Bhat

2014-01-01

Full Text Available Background: Diabetes mellitus is a major complication of iron overload in patients with beta thalassemia major. Design: This is a descriptive study conducted in a Tertiary Care Teaching Hospital to analyze beta cell function and insulin resistance, and their relation to iron overload status in beta thalassemia major. Fasting glucose, two-hour post load glucose, fasting insulin, alanine amino transaminase (ALT, and ferritin were used as outcome measures. The homeostatic model assessment (HOMA model was used to calculate the beta cell function and insulin resistance index. Results: Of the 30 cases, 20% had impaired fasting glucose, 3.3% had impaired glucose tolerance, and none had diabetes. Fasting glucose was not significant between the cases and controls (P = 0.113. Fasting insulin (P = 0.001, ferritin (P = 0.001, and ALT (P = 0.001 levels were significantly high in the cases. Insulin resistance index was significantly higher in the cases (P = 0.001 as also the beta cell function (P = 0.001. With increase in age and the number of units transfused there is a decline in beta cell function, fasting insulin, and insulin resistance after attaining the maximum level. This suggests that initial insulin resistance is followed by insulin depletion due to loss of beta cell function, leading to diabetes mellitus. Conclusion: Impaired glucose tolerance (IGT and insulin resistance precede the onset of insulin-dependent diabetes and adequate chelation therapy is essential for delaying the onset or for prevention of diabetes.

A General LC-MS/MS Method for Monitoring Potential β-Lactam Contamination in Drugs and Drug-Manufacturing Surfaces.

Science.gov (United States)

Qiu, Chen; Zhu, Hongbin; Ruzicka, Connie; Keire, David; Ye, Hongping

2018-05-15

Penicillins and some non-penicillin β-lactams may cause potentially life-threatening allergic reactions. Thus, possible cross contamination of β-lactams in food or drugs can put people at risk. Therefore, when there is a reasonable possibility that a non-penicillin product could be contaminated by penicillin, the drug products are tested for penicillin contamination. Here, a sensitive and rapid method for simultaneous determination of multiple β-lactam antibiotics using high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and validated. Mass spectral acquisition was performed on a Q-Exactive HF mass spectrometer in positive ion mode with parallel reaction monitoring (PRM). The method was validated for seven β-lactam antibiotics including one or two from each class and a synthetic intermediate. The quantification precision and accuracy at 200 ppb were in the range of ± 1.84 to ± 4.56 and - 5.20 to 3.44%, respectively. The limit of detection (LOD) was 0.2 ppb, and the limit of quantitation (LOQ) was 2 ppb with a linear dynamic range (LDR) of 2-2000 ppb for all eight β-lactams. From various drug products, the recoveries of eight β-lactams at 200 and 2 ppb ranged from 93.8 ± 3.2 to 112.1 ± 4.2% and 89.7 ± 4.6 to 110.6 ± 1.9%, respectively. The application of the method for detecting cross contamination of trace β-lactams (0.2 ppb) and for monitoring facility surface cleaning was also investigated. This sensitive and fast method was fit-for-purpose for detecting and quantifying trace amount of β-lactam contamination, monitoring cross contamination in manufacturing processes, and determining potency for regulatory purposes and for quality control.

Crystal structure of tabtoxin resistance protein complexed with acetyl coenzyme A reveals the mechanism for beta-lactam acetylation.

Science.gov (United States)

He, Hongzhen; Ding, Yi; Bartlam, Mark; Sun, Fei; Le, Yi; Qin, Xincheng; Tang, Hong; Zhang, Rongguang; Joachimiak, Andrzej; Liu, Jinyuan; Zhao, Nanming; Rao, Zihe

2003-01-31

Tabtoxin resistance protein (TTR) is an enzyme that renders tabtoxin-producing pathogens, such as Pseudomonas syringae, tolerant to their own phytotoxins. Here, we report the crystal structure of TTR complexed with its natural cofactor, acetyl coenzyme A (AcCoA), to 1.55A resolution. The binary complex forms a characteristic "V" shape for substrate binding and contains the four motifs conserved in the GCN5-related N-acetyltransferase (GNAT) superfamily, which also includes the histone acetyltransferases (HATs). A single-step mechanism is proposed to explain the function of three conserved residues, Glu92, Asp130 and Tyr141, in catalyzing the acetyl group transfer to its substrate. We also report that TTR possesses HAT activity and suggest an evolutionary relationship between TTR and other GNAT members.

Mixtures of beta distributions in models of the duration of a project affected by risk

Science.gov (United States)

Gładysz, Barbara; Kuchta, Dorota

2017-07-01

This article presents a method for timetabling a project affected by risk. The times required to carry out tasks are modelled using mixtures of beta distributions. The parameters of these beta distributions are given by experts: one corresponding to the duration of a task in stable conditions, with no risks materializing, and the other corresponding to the duration of a task in the case when risks do occur. Finally, a case study will be presented and analysed: the project of constructing a shopping mall in Poland.

[Antibiotic resistance: measures urgently needed].

NARCIS (Netherlands)

Kluytmans, J.; Vandenbroucke-Grauls, C.M.; Meer, J.W.M. van der

2010-01-01

Antimicrobial resistance is increasing rapidly and there are hardly any new antimicrobial agents to be expected in the coming years. The number of patients affected by extended spectrum beta-lactamase producing organisms (ESBLs) is rising and there are strong indications that this is caused in part

ICU Acquisition Rate, Risk Factors, and Clinical Significance of Digestive Tract Colonization With Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae: A Systematic Review and Meta-Analysis.

Science.gov (United States)

Detsis, Marios; Karanika, Styliani; Mylonakis, Eleftherios

2017-04-01

To evaluate the acquisition rate, identify risk factors, and estimate the risk for subsequent infection, associated with the colonization of the digestive tract with extended-spectrum beta-lactamase-producing Enterobacteriaceae during ICU-hospitalization. PubMed, EMBASE, and reference lists of all eligible articles. Included studies provided data on ICU-acquired colonization with extended-spectrum beta-lactamase-producing Enterobacteriaceae in previously noncolonized and noninfected patients and used the double disk synergy test for extended-spectrum beta-lactamase-producing Enterobacteriaceae phenotypic confirmation. Studies reporting extended-spectrum beta-lactamase-producing Enterobacteriaceae outbreaks or data on pediatric population were excluded. Two authors independently assessed study eligibility and performed data extraction. Thirteen studies (with 15,045 ICUs-patients) were evaluated using a random-effect model and a meta-regression analysis. The acquisition rate of digestive tract colonization during ICU stay was 7% (95% CI, 5-10) and it varies from 3% (95% CI, 2-4) and 4% (95% CI, 2-6) in the Americas and Europe to 21% (95% CI, 9-35) in the Western Pacific region. Previous hospitalization (risk ratio, 1.57 [95% CI, 1.07-2.31]) or antibiotic use (risk ratio, 1.65 [95% CI, 1.15-2.37]) and exposure to beta-lactams/beta-lactamase inhibitors (risk ratio, 1.78 [95% CI, 1.24-2.56]) and carbapenems (risk ratio, 2.13 [95% CI, 1.49-3.06]) during the ICU stay were independent risk factors for ICU-acquired colonization. Importantly, colonized patients were more likely to develop an extended-spectrum beta-lactamase-producing Enterobacteriaceae infection (risk ratio, 49.62 [95% CI, 20.42-120.58]). The sensitivity and specificity of prior colonization to predict subsequent extended-spectrum beta-lactamase-producing Enterobacteriaceae infection were 95.1% (95% CI, 54.7-99.7) and 89.2% (95% CI, 77.2-95.3), respectively. The ICU acquisition rate of extended-spectrum beta

Maternal Rat Diabetes Mellitus Deleteriously Affects Insulin Sensitivity and Beta-Cell Function in the Offspring

Directory of Open Access Journals (Sweden)

Abdel-Baset M. Aref

2013-01-01

Full Text Available This study was designed to assess the effect of maternal diabetes in rats on serum glucose and insulin concentrations, insulin resistance, histological architecture of pancreas and glycogen content in liver of offspring. The pregnant rat females were allocated into two main groups: normal control group and streptozotocin-induced diabetic group. After birth, the surviving offspring were subjected to biochemical and histological examination immediately after delivery and at the end of the 1st and 2nd postnatal weeks. In comparison with the offspring of normal control dams, the fasting serum glucose level of offspring of diabetic mothers was significantly increased at the end of the 1st and 2nd postnatal weeks. Serum insulin level of offspring of diabetic dams was significantly higher at birth and decreased significantly during the following 2 postnatal weeks, while in normal rat offspring, it was significantly increased with progress of time. HOMA Insulin Resistance (HOMA-IR was significantly increased in the offspring of diabetic dams at birth and after 1 week than in normal rat offspring, while HOMA insulin sensitivity (HOMA-IS was significantly decreased. HOMA beta-cell function was significantly decreased at all-time intervals in offspring of diabetic dams. At birth, islets of Langerhans as well as beta cells in offspring of diabetic dams were hypertrophied. The cells constituting islets seemed to have a high division rate. However, beta-cells were degenerated during the following 2 post-natal weeks and smaller insulin secreting cells predominated. Vacuolation and necrosis of the islets of Langerhans were also observed throughout the experimental period. The carbohydrate content in liver of offspring of diabetic dams was at all-time intervals lower than that in control. The granule distribution was more random. Overall, the preexisting maternal diabetes leads to glucose intolerance, insulin resistance, and impaired insulin sensitivity and �

In vitro activity and stability against novel beta-lactamases of investigational beta-lactams (cefepime, cefpirome, flomoxef, SCE2787 and piperacillin plus tazobactam) in comparison with established compounds (cefotaxime, latamoxef and piperacillin).

Science.gov (United States)

Bauernfeind, A; Schweighart, S; Eberlein, E; Jungwirth, R

1991-01-01

The therapeutic perspectives of flomoxef, SCE 2787, cefpirome, cefepime, latamoxef, cefotaxime and of piperacillin plus tazobactam were comparatively evaluated by their in vitro activity against 1119 clinical isolates of 83 bacterial species. Escherichia coli, Klebsiella spp. Enterobacter sakazakii, Proteus spp. and Shigella spp. were about equally susceptible to the cephalosporins (MIC90: 0.06 to 0.5 mg/l), while the MIC90 for piperacillin plus tazobactam was between 2 and 16 mg/l. Enterobacter cloacae, Enterobacter aerogenes and Serratia spp. were most susceptible to SCE 2787, cefpirome and cefepime (MIC90: 0.06 to 2 mg/l) followed by latamoxef, cefotaxime, flomoxef and piperacillin plus tazobactam. For Citrobacter spp., Providencia spp. and Yersinia enterocolitica MIC90 were between 0.06 and 0.5 mg/l. Flomoxef was between 2 to 4 log2 less active against these species but more active than piperacillin plus tazobactam (MIC90: 2 and 8 mg/l). Morganella morganii and Hafnia alvei were most susceptible to cefepime, cefpirome and latamoxef (MIC90: 0.13 to 0.5 mg/l) while cefotaxime (MIC90: 8 mg/l) and piperacillin plus tazobactam (MIC90: 8 and greater than 64 mg/l) were the least active compounds. SCE 2787, cefepime and cefpirome were the most potent beta-lactams against the majority of the 13 species of non-fermentative bacilli (NFB) investigated (MIC90: 0.5 to 16 mg/l). The oxacephems were the least active compounds against NFB. Cefepime was the most active of the compounds included against Pseudomonas aeruginosa (MIC90: 16 mg/l). Haemophilus spp., Neisseria gonorrhoeae and Bordetella pertussis were most susceptible to cefotaxime (MIC90: 0.03 to 0.06 mg/l). Latamoxef had the lowest activity of all compounds against gram-positive cocci. Flomoxef was the most active compound against penicillinase producing Staphylococcus aureus and about equally active as the other betalactams against methicillin susceptible staphylococci of other staphylococcal species

Crystal structure of tabtoxin resistance protein complexed with acetyl coenzyme A reveals the mechanism for {beta}-lactam acetylation.

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He, H.; Ding, Y.; Bartlam, M.; Sun, F.; Le, Y.; Qin, X.; Tang, H.; Zhang, R.; Joachimiak, A.; Liu, J.; Zhao, N.; Rao, Z.; Biosciences Division; Tsinghua Univ.; Chinese Academy of Science

2003-01-31

Tabtoxin resistance protein (TTR) is an enzyme that renders tabtoxin-producing pathogens, such as Pseudomonas syringae, tolerant to their own phytotoxins. Here, we report the crystal structure of TTR complexed with its natural cofactor, acetyl coenzyme A (AcCoA), to 1.55 {angstrom} resolution. The binary complex forms a characteristic 'V' shape for substrate binding and contains the four motifs conserved in the GCN5-related N-acetyltransferase (GNAT) superfamily, which also includes the histone acetyltransferases (HATs). A single-step mechanism is proposed to explain the function of three conserved residues, Glu92, Asp130 and Tyr141, in catalyzing the acetyl group transfer to its substrate. We also report that TTR possesses HAT activity and suggest an evolutionary relationship between TTR and other GNAT members.

Virulence and antimicrobial resistance of common urinary bacteria from asymptomatic students of Niger Delta University, Amassoma, Bayelsa State, Nigeria

Directory of Open Access Journals (Sweden)

Adebola Onanuga

2016-01-01

Full Text Available Background: Asymptomatic bacteriuria frequently occurs among all ages with the possibility of developing into urinary tract infections, and the antimicrobial resistance patterns of the etiologic organisms are essential for appropriate therapy. Thus, we investigated the virulence and antimicrobial resistance patterns of common urinary bacteria in asymptomatic students of Niger Delta University, Amassoma, Bayelsa State, Nigeria in a cross-sectional study. Materials and Methods: Clean catch mid-stream early morning urine samples collected from 200 asymptomatic University students of aged ranges 15–30 years were cultured, screened and common bacteria were identified using standard microbiological procedures. The isolates were screened for hemolysin production and their susceptibility to antibiotics was determined using standard disc assay method. Results: A total prevalence rate of 52.0% significant bacteriuria was detected and it was significantly higher among the female with a weak association (χ2 = 6.01, phi = 0.173, P = 0.014. The Klebsiella pneumoniae and Staphylococcus aureus isolates were most frequently encountered among the isolated bacteria and 18 (12.7% of all the bacterial isolates produced hemolysins. All the bacterial isolates exhibited 50–100% resistance to the tested beta-lactam antibiotics, tetracycline and co-trimoxazole. The isolated bacteria were 85-100% multi-drug resistant. However, most of the isolates were generally susceptible to gentamicin and ofloxacin. The phenotypic detection of extended-spectrum beta-lactamases was 9 (9.6% among the tested Gram-negative bacterial isolates. Conclusions: The observed high proportions of multidrug resistant urinary bacteria among asymptomatic University students call for the need of greater control of antibiotic use in this study area.

Monitoring and evaluation of antibiotic resistance genes in four municipal wastewater treatment plants in Harbin, Northeast China.

Science.gov (United States)

Wen, Qinxue; Yang, Lian; Duan, Ruan; Chen, Zhiqiang

2016-05-01

The development and proliferation of antibiotic resistance in pathogenic and environmental microorganisms is of great concern for public health. In this study, the distribution and removal efficiency of intI1 and eight subtypes of antibiotic resistance genes (ARGs) for tetracycline, sulfonamides, beta-lactams resistance in four municipal wastewater treatment plants (WWTPs) in Harbin, which locates in Songhua River basin in cold areas of China, were monitored by real-time fluorescent quantitative PCR. The results showed that intI1 and 6 ARGs except for blaTEM and blaSHV were detected in wastewater and sludge samples and 0.3-2.7 orders of magnitude of ARGs removal efficiency in the four WWTPs were observed. The investigation on the removal of ARGs of different treatment units in one WWTP showed that the biological treatment unit played the most important role in ARGs removal (1.2-1.8 orders of magnitude), followed by UV disinfection, while primary physical treatment units can hardly remove any ARGs. Although all the WWTPs can remove ARGs effectively, ARGs concentrations are still relatively high in the effluent, their further attenuation should be investigated. Copyright © 2016 Elsevier Ltd. All rights reserved.

Current trends of human infections and antibiotic resistance of the genus Shewanella.

Science.gov (United States)

Yousfi, K; Bekal, S; Usongo, V; Touati, A

2017-08-01

Shewanella spp. are commonly known as environmental bacteria and are most frequently isolated from aquatic areas. Currently, diseases syndromes and multidrug resistance have increasingly been reported in the genus Shewanella. Some species are associated with various infections, such as skin and soft tissue infections, as well as bacteremia. Generally, these bacteria are opportunistic and mostly affect people with an impaired immune system. This genus is also a probable vehicle and progenitor of antibiotic resistance genes. In fact, several resistance genes and mobile genetic elements have been identified in some resistant species isolated from environmental or clinical settings. These genes confer resistance to different antibiotic classes, including those used in therapies such as β-lactams and quinolones, and are generally located on the chromosome. Recently, a multidrug-resistant (MDR) plasmid harboring several drug resistance genes associated with transposons and integrons has been identified in Shewanella xiamenensis. These antibiotic resistance genes can circulate in the environment and contribute to the emergence of antibiotic resistance. This review describes different aspects of Shewanella, focusing on the infections caused by this genus, as well as their role in the propagation of antibiotic resistance via mobile genetic elements.

[Molecular and structural-biological analysis of Nicotiana plumbaginifolia mutants for identification of the site of beta-tubulins interaction with dinitroanilines and phosphorotioamidates].

Science.gov (United States)

Emets, A I; Baiard, U V; Nyporko, A Iu; Swire-Clark, G A; Blium, Ia B

2009-01-01

The identification of point mutation locations on beta-tubulin molecules of amiprophosmethyl- and trifluralin-resistant Nicotiana plumbaginifolia lines have described in the work. It was shown that in the first case this mutation is connected with the substitution ofserine residue on proline in position 248; in the second case--with the substitution of phenilalanine on serine in position 317 of beta-tubulin amino acid sequence. Three-dimensional models of beta-tubulin molecule from Chlamydomonas with well-known location of mutations conferring dinitroaniline- and phosphorotioamidate resistance (substitution of lysine residue to methionine on position 350), and beta-tubulin from Nicotiana plumbaginifolia have been reconstructed. On the basis of analysis of site of interaction with dinitroanilines and phosphorotioamides on Chlamydomonas beta-tubulin molecule it was concluded that the revealed mutations on Nicotiana plumbaginifolia beta-tubulin affect amino acid residues participating in formation of this site.

Prevalence and Pattern of Methicillin Resistant Staphylococcus ...

African Journals Online (AJOL)

This trend is on the increase consequently there is prolong hospital stay, increased hospital bills, and increased morbidity and mortality. The widespread use of antimicrobial agents such as the â- lactam antibiotics has contributed to the emergence of Methicillin Resistant Staphylococcus aureus(MRSA); which has become ...

Altered membrane permeability in multidrug resistant Escherichia ...

African Journals Online (AJOL)

The study was conducted with the objective of examining the outer membrane proteins and their involvement during the transport of β - lactams in multidrug resistant Escherichia coli isolated from extra-intestinal infections. Also, the response of gram negative bacterial biomembrane alteration was studied using extended ...

Recommendations for clinical use of data on neutralising antibodies to interferon-beta therapy in multiple sclerosis

DEFF Research Database (Denmark)

Polman, Chris H; Bertolotto, Antonio; Deisenhammer, Florian

2010-01-01

in MS and NAbs to interferon-beta therapy convened in Amsterdam, Netherlands, under the auspices of the Neutralizing Antibodies on Interferon beta in Multiple Sclerosis consortium, a European-based project of the 6th Framework Programme of the European Commission, to review and discuss data on NAbs......The identification of factors that can affect the efficacy of immunomodulatory drugs in relapsing-remitting multiple sclerosis (MS) is important. For the available interferon-beta products, neutralising antibodies (NAb) have been shown to affect treatment efficacy. In June, 2009, a panel of experts...... and their practical consequences for the treatment of patients with MS on interferon beta. The panel believed that information about NAbs and other markers of biological activity of interferons (ie, myxovirus resistance protein A [MxA]) can be integrated with clinical and imaging indicators to guide individual...

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.

Neoplastic progression of rat tracheal epithelial cells involves resistance to transforming growth factor beta

International Nuclear Information System (INIS)

Hubbs, A.F.; Hahn, F.F.; Thomassen, D.G.

1988-01-01

Primary, transformed, and tumor-derived rat tracheal epithelial (RTE) cells were grown in serum-free medium containing 0 to 300 pg/mL transforming growth factor beta (TGFβ) markedly inhibited the growth of primary RTE cells with a 50% drop in the efficiency of colony formation seen at TGFβ concentrations between 10 and 30 pg/ mL. The effect of TGFβ on preneoplastic RTE cells was similar to the effect on normal primary RTE cells. Cell lines established from tumors produced by inoculation of transformed RTE cells into nude mice were relatively resistant to -TGFβ-induced growth inhibition. Resistance to TGFβ-induced growth inhibition, therefore, appears to be a late event in the development of neoplasia. (author)

Antibiotic resistance and virulence genes in coliform water isolates.

Science.gov (United States)

Stange, C; Sidhu, J P S; Tiehm, A; Toze, S

2016-11-01

Widespread fecal pollution of surface water may present a major health risk and a significant pathway for dissemination of antibiotic resistance bacteria. The River Rhine is one of the longest and most important rivers in Europe and an important raw water source for drinking water production. A total of 100 coliform isolates obtained from River Rhine (Germany) were examined for their susceptibility to seven antimicrobial agents. Resistances against amoxicillin, trimethoprim/sulfamethoxazole and tetracycline were detected in 48%, 11% and 9% of isolates respectively. The antibiotic resistance could be traced back to the resistance genes bla TEM , bla SHV , ampC, sul1, sul2, dfrA1, tet(A) and tet(B). Whereby, the ampC gene represents a special case, because its presence is not inevitably linked to a phenotypic antibiotic resistance. Multiple antibiotics resistance was often accompanied by the occurrence of class 1 or 2 integrons. E. coli isolates belonging to phylogenetic groups A and B1 (commensal) were more predominant (57%) compared to B2 and D groups (43%) which are known to carry virulent genes. Additionally, six E. coli virulence genes were also detected. However, the prevalence of virulence genes in the E. coli isolates was low (not exceeding 4.3% per gene) and no diarrheagenic E. coli pathotypes were detected. This study demonstrates that surface water is an important reservoir of ARGs for a number of antibiotic classes such as sulfonamide, trimethoprim, beta-lactam-antibiotics and tetracycline. The occurrence of antibiotic resistance in coliform bacteria isolated from River Rhine provides evidence for the need to develop management strategies to limit the spread of antibiotic resistant bacteria in aquatic environment. Copyright © 2016 Elsevier GmbH. All rights reserved.

Monitoring and evaluation of antibiotic resistance genes in four municipal wastewater treatment plants in Harbin, Northeast China

International Nuclear Information System (INIS)

Wen, Qinxue; Yang, Lian; Duan, Ruan; Chen, Zhiqiang

2016-01-01

The development and proliferation of antibiotic resistance in pathogenic and environmental microorganisms is of great concern for public health. In this study, the distribution and removal efficiency of intI1 and eight subtypes of antibiotic resistance genes (ARGs) for tetracycline, sulfonamides, beta-lactams resistance in four municipal wastewater treatment plants (WWTPs) in Harbin, which locates in Songhua River basin in cold areas of China, were monitored by real-time fluorescent quantitative PCR. The results showed that intI1 and 6 ARGs except for bla_T_E_M and bla_S_H_V were detected in wastewater and sludge samples and 0.3–2.7 orders of magnitude of ARGs removal efficiency in the four WWTPs were observed. The investigation on the removal of ARGs of different treatment units in one WWTP showed that the biological treatment unit played the most important role in ARGs removal (1.2–1.8 orders of magnitude), followed by UV disinfection, while primary physical treatment units can hardly remove any ARGs. Although all the WWTPs can remove ARGs effectively, ARGs concentrations are still relatively high in the effluent, their further attenuation should be investigated. - Highlights: • The distribution of 8 ARGs and intI1 in WWTPs in Harbin in winter were monitored. • ARGs removal in 4 WWTPs with different processes were investigated. • Biological treatment process plays the most important role in ARGs removal. • A relatively high level of ARGs is still present in the effluent after wastewater treatment. • Regional uses of antibiotics other than season temperature affects the fate of ARGs in WWTPs.

Beta-lactamases in Enterobacteriaceae in broilers

NARCIS (Netherlands)

Dierikx, C.M.

2013-01-01

Resistance to cephalosprins due to the production of extended spectrum beta-lactamases (ESBLs) or plasmid mediated AmpC beta-lactamases is increasingly found in infections in humans outside the hospital. The genes encoding for these beta-lactamases are located on mobile DNA (plasmids), which can be

Antimicrobial resistance determinants among anaerobic bacteria isolated from footrot.

Science.gov (United States)

Lorenzo, María; García, Nuria; Ayala, Juan Alfonso; Vadillo, Santiago; Píriz, Segundo; Quesada, Alberto

2012-05-25

Antibiotic resistance has been evaluated among 36 Gram negative and anaerobic bacilli (10 Bacteroides, 11 Prevotella, 7 Porphyromonas and 8 Fusobacterium strains) isolated from clinical cases of caprine and ovine footrot (necrotic pododermatitis). The initial analysis on this bacterial consortium evaluates the relationships existing among antimicrobial resistance determinants, phenotype expression and mobilization potential. The Bacteroides strains were generally resistant to penicillins, first-generation cephalosporins, tetracycline and erythromycin, and expressed low level of β-lactamase activity. The main determinants found among the Bacteroides strains were cepA and tetQ genes, conferring resistance to β-lactams and tetracycline, respectively. A general susceptibility to β-lactams was shown for most Prevotella, Porphyromonas and Fusobacterium strains, where none of the β-lactamase genes described in Bacteroides was detected. Resistance to tetracycline and/or erythromycin was found among the three bacterial groups. Although tetQ genes were detected for several Prevotella and Porphyromonas strains, a unique ermF positive was revealed among Prevotella strains. The expression of resistance markers was not related with the polymorphism of their coding sequences. However, the finding of sequence signatures for conjugative transposons in the vicinities of tetQ and ermF suggests a mobilization potential that might have contributed to the spread of antimicrobial resistance genes. Copyright © 2011 Elsevier B.V. All rights reserved.

Preliminary evaluation of beta-spodumene as a fusion reactor structural material

International Nuclear Information System (INIS)

Kelsey, P.V. Jr.; Schmunk, R.E.; Henslee, S.P.

1982-01-01

Beta-spodumene was investigated as a candidate material for use in fusion reactor environments. Properties which support the use of beta-spodumene include good thermal shock resistance, a very low coefficient of thermal expansion, a low-Z composition which would result in minimum impact on the plasma, and flexibility in fabrication processes. Specimens were irradiated in the Advanced Test Reactor (ATR) to a fluence of 5.3 x 10 22 n/m 2 , E > MeV, and 4.9 x 10 23 n/m 2 thermal fluence in order to obtain a preliminary evaluation of the impact of irradiation on the material. Preliminary data indicate that the mechanical properties of beta-spodumene are little affected by irradiation. Gas production and release have also been investigated. (orig.)

Quantitative studies on resistance to Polymyxa betae and beet necrotic yellow vein virus in beet = Kwantitatief onderzoek naar resistentie tegen Polymyxa betae en het bieterhizomanievirus in de biet

NARCIS (Netherlands)

Paul, H.

1993-01-01

Beet necrotic yellow vein virus (BNYVV) causes rhizomania in sugar beet. The virus is transmitted by the soil-borne fungus Polymyxa betae . Rhizomania in sugar beet can cause serious losses in sugar yield. Breeding for resistance is the most promising way to control the

Plasmid-Mediated Quinolone Resistance in Shigella flexneri Isolated From Macaques

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Anthony J. Mannion

2018-03-01

Full Text Available Non-human primates (NHPs for biomedical research are commonly infected with Shigella spp. that can cause acute dysentery or chronic episodic diarrhea. These animals are often prophylactically and clinically treated with quinolone antibiotics to eradicate these possible infections. However, chromosomally- and plasmid-mediated antibiotic resistance has become an emerging concern for species in the family Enterobacteriaceae. In this study, five individual isolates of multi-drug resistant Shigella flexneri were isolated from the feces of three macaques. Antibiotic susceptibility testing confirmed resistance or decreased susceptibility to ampicillin, amoxicillin-clavulanic acid, cephalosporins, gentamicin, tetracycline, ciprofloxacin, enrofloxacin, levofloxacin, and nalidixic acid. S. flexneri isolates were susceptible to trimethoprim-sulfamethoxazole, and this drug was used to eradicate infection in two of the macaques. Plasmid DNA from all isolates was positive for the plasmid-encoded quinolone resistance gene qnrS, but not qnrA and qnrB. Conjugation and transformation of plasmid DNA from several S. flexneri isolates into antibiotic-susceptible Escherichia coli strains conferred the recipients with resistance or decreased susceptibility to quinolones and beta-lactams. Genome sequencing of two representative S. flexneri isolates identified the qnrS gene on a plasmid-like contig. These contigs showed >99% homology to plasmid sequences previously characterized from quinolone-resistant Shigella flexneri 2a and Salmonella enterica strains. Other antibiotic resistance genes and virulence factor genes were also identified in chromosome and plasmid sequences in these genomes. The findings from this study indicate macaques harbor pathogenic S. flexneri strains with chromosomally- and plasmid-encoded antibiotic resistance genes. To our knowledge, this is the first report of plasmid-mediated quinolone resistance in S. flexneri isolated from NHPs and warrants

Beta-alanine supplementation improves jumping power and affects severe-intensity performance in professional alpine skiers.

Science.gov (United States)

Gross, Micah; Bieri, Kathrin; Hoppeler, Hans; Norman, Barbara; Vogt, Michael

2014-12-01

Supplementation with beta-alanine may have positive effects on severe-intensity, intermittent, and isometric strength-endurance performance. These could be advantageous for competitive alpine skiers, whose races last 45 to 150 s, require metabolic power above the aerobic maximum, and involve isometric muscle work. Further, beta-alanine supplementation affects the muscle force-frequency relationship, which could influence explosiveness. We explored the effects of beta-alanine on explosive jump performance, severe exercise energy metabolism, and severe-intensity ski-like performance. Nine male elite alpine skiers consumed 4.8 g/d beta-alanine or placebo for 5 weeks in a double-blind fashion. Before and after, they performed countermovement jumps (CMJ), a 90-s cycling bout at 110% VO2max (CLT), and a maximal 90-s box jump test (BJ90). Beta-alanine improved maximal (+7 ± 3%, d = 0.9) and mean CMJ power (+7 ± 2%, d = 0.7), tended to reduce oxygen deficit (-3 ± 8%, p = .06) and lactate accumulation (-12 ± 31%) and enhance aerobic energy contribution (+1.3 ± 2.9%, p = .07) in the CLT, and improved performance in the last third of BJ90 (+7 ± 4%, p = .02). These effects were not observed with placebo. Beta-alanine supplementation improved explosive and repeated jump performance in elite alpine skiers. Enhanced muscle contractility could possibly explain improved explosive and repeated jump performance. Increased aerobic energy production could possibly help explain repeated jump performance as well.

Pseudomonas aeruginosa: evaluation of pathogen burden and drug-resistance trends in a tertiary care hospital

International Nuclear Information System (INIS)

Saeed, M.; Hussain, S.; Ahmad, A.

2018-01-01

To evaluate the pathogen burden and antibiotic-resistance trends of Pseudomonas aeruginosa among hospitalised patients at a tertiary care hospital. Study Design:Retrospective, hospital record-based, cross-sectional study. Place and Duration of Study:Microbiology Laboratory, Allama Iqbal Medical College/Jinnah Hospital, Lahore, from January 2014 to December 2016. Methodology:A total of 5,960 samples were collected from clinically suspected cases of bacterial infections, admitted to the hospital. Microbial identification and antibiotic susceptibility pattern were carried out and analysed. Results:Out of a total of 5,960 samples, Pseudomonas aeruginosawas isolated from 1,268 (21.2%) specimens. Department-wise isolation rate was n=600 (42.9%), n=268 (15.4%), n=201 (12.6%), and n=199 (16.0%) from intensive care unit (ICU), surgical units, medical units, and Gynae wards, respectively (p<0.0001). Sample-wise isolation rate was, wound swabs n=448 (35%), urine n=356 (28%), sputum n=187 (14 %), tracheal aspirate n=127 (10%), blood n=99 (7%), and broncho-alveolar lavage n=51 (4%) (p<0.0001). Drug-resistance pattern showed low rates for carbapenems (meropenem n=440 (35%), Imipenem n=436 (34%) and beta-lactam + beta-lactamase inhibitor combination (piperacillin+ tazobactam n=437 (34%) while alarming rates were observed for cephalosporins (ceftazidime n=716 (56%), fluoroquinolones (ciprofloxacin n=690 (54%), cefoperazone+sulbactam n=685 (54%), aminoglycosides (gentamicin, n=669 (53%), amikacin n=608 (48%), and monobactams (aztreonam n=666 (52%). Decreasing trend was observed only for amikacin 63% to 37%, aztreonam showed similar pattern throughout, while there was an increasing trend of drug resistance in all groups of antibiotics. Conclusion:Emerging drug-resistant strains of Pseudomonas aeruginosaare probably linked to the injudicious use of antibiotics, leading to ineffective empirical therapy. Therefore, we suggest that culture and antimicrobial susceptibility testing should

Enantioselective construction of quaternary N-heterocycles by palladium-catalysed decarboxylative allylic alkylation of lactams

KAUST Repository

Behenna, Douglas C.

2011-12-18

The enantioselective synthesis of nitrogen-containing heterocycles (N-heterocycles) represents a substantial chemical research effort and resonates across numerous disciplines, including the total synthesis of natural products and medicinal chemistry. In this Article, we describe the highly enantioselective palladium-catalysed decarboxylative allylic alkylation of readily available lactams to form 3,3-disubstituted pyrrolidinones, piperidinones, caprolactams and structurally related lactams. Given the prevalence of quaternary N-heterocycles in biologically active alkaloids and pharmaceutical agents, we envisage that our method will provide a synthetic entry into the de novo asymmetric synthesis of such structures. As an entry for these investigations we demonstrate how the described catalysis affords enantiopure quaternary lactams that intercept synthetic intermediates previously used in the synthesis of the Aspidosperma alkaloids quebrachamine and rhazinilam, but that were previously only available by chiral auxiliary approaches or as racemic mixtures. © 2012 Macmillan Publishers Limited. All rights reserved.

Effect of atorvastatin on pancreatic Beta-cell function and insulin resistance in type 2 diabetes mellitus patients: a randomized pilot study.

Science.gov (United States)

Goyal, Aman; Singh, Surender; Tandon, Nikhil; Gupta, Nandita; Gupta, Yogendra Kumar

2014-12-01

Statins are commonly used for the management of dyslipidemia in type 2 diabetes mellitus patients. We hypothesized that atorvastatin could modulate the beta-cell function by altering the levels of proapoptotic and antiapoptotic lipoproteins and could also have an effect on insulin resistance. The aim of the present pilot study was to assess the effect of atorvastatin 10 mg on pancreatic beta-cell function and insulin resistance in patients with hyperlipidemia and type 2 diabetes by using the homeostasis model assessment-2 (HOMA2) index. Fifty-one type 2 diabetes patients receiving oral antidiabetes drugs, not taking statins, with baseline low-density lipoprotein cholesterol between 2.6 mmol/L and 4.1 mmol/L were included. Forty-three patients (21 in placebo group and 22 in atorvastatin group) completed the study and were taken up for final analysis. Fasting blood samples were obtained at baseline and at 12 weeks to determine levels of blood glucose, lipid profile, insulin, C-peptide and glycosylated hemoglobin (A1C). Atorvastatin nonsignificantly increased fasting serum insulin (+14.29%, p=0.18), accompanied by marginal nonsignificant increases in fasting plasma glucose and A1C. There was a decrease in HOMA2 percent beta-cell function (-2.9%, p=0.72) and increase in HOMA2 insulin resistance (+14%, p=0.16) in the atorvastatin group as compared with baseline, but the difference was not statistically significant. Atorvastatin in the dose used failed to produce significant change in pancreatic beta-cell function and insulin resistance in type 2 diabetes patients as assessed by the HOMA2 index. The possible explanations include absence of lipotoxicity at prevailing levels of dyslipidemia at baseline or inadequacy of statin dose used in the study. (Clinical Trials Registry-India: CTRI/2008/091/000099). Copyright © 2014 Canadian Diabetes Association. Published by Elsevier Inc. All rights reserved.

Dgroup: DG01212 [KEGG MEDICUS

Lifescience Database Archive (English)

Full Text Available DG01212 Chemical ... DGroup Imipenem ... D04515 ... Imipenem (INN) D00206 ... Imipenem (USP); Imipene...m hydrate (JP17) Antibacterial ... DG01710 ... beta-Lactam antibiotic ... DG01713 ... Penicillin skeleton group ... DG01458 ... Carbapene...m ... beta-Lactam antibiotics, carbapenem penicillin binding protein ...

Risk Factor Analysis of Ciprofloxacin-Resistant and Extended Spectrum Beta-Lactamases Pathogen-Induced Acute Bacterial Prostatitis in Korea.

Science.gov (United States)

Lee, Young; Lee, Dong Gi; Lee, Sang Hyub; Yoo, Koo Han

2016-11-01

The objectives of this study were to investigate risk factors and the incidence of ciprofloxacin resistance and extended-spectrum beta-lactamases (ESBL) in patients with acute bacterial prostatitis (ABP). We reviewed the medical records of 307 patients who were diagnosed with ABP between January 2006 and December 2015. The etiologic pathogens and risk factors for ciprofloxacin-resistant E. coli and ESBL-producing microbes, susceptibility to ciprofloxacin, and the incidence of ESBL in patients with ABP were described. History of prior urologic manipulation was an independent risk factor for ciprofloxacin-resistant (P = 0.005) and ESBL-producing microbes (P = 0.005). Advanced age (over 60 years) was an independent risk factor for ciprofloxacin-resistant microbes (P = 0.022). The ciprofloxacin susceptibility for Escherichia coli in groups without prior manipulation was documented 85.7%. For groups with prior manipulation, the susceptibility was 10.0%. Incidence of ESBL-producing microbes by pathogen was 3.8% for E. coli and 1.0% for Klebsiella pneumonia in the absence of manipulation group, and 20% and 33.3% in the presence of manipulation group, respectively. Initial treatment of ABP must consider patient's age and the possibility of prior manipulation to optimize patient treatment. With the high rate of resistance to fluoroquinolone, cephalosporins with amikacin, or carbapenems, or extended-spectrum penicillin with beta lactamase inhibitor should be considered as the preferred empirical ABP treatment in the patients with history of prior urologic manipulation.

Enzymatic synthesis of ß-lactam antibiotics via direct condensation

NARCIS (Netherlands)

Ulijn, R.V.; Martin, de L.; Halling, P.J.; Moore, B.D.; Janssen, A.E.M.

2002-01-01

In this paper, the feasibility of precipitation driven synthesis of acidic and zwitterionic -lactam antibiotics is studied. As an example of the first type, penicillin G was produced in good yield (160 mmol kg-1) directly from the free acid and amine aqueous substrate suspension, where the synthesis

Adaptive Landscapes of Resistance Genes Change as Antibiotic Concentrations Change.

Science.gov (United States)

Mira, Portia M; Meza, Juan C; Nandipati, Anna; Barlow, Miriam

2015-10-01

Most studies on the evolution of antibiotic resistance are focused on selection for resistance at lethal antibiotic concentrations, which has allowed the detection of mutant strains that show strong phenotypic traits. However, solely focusing on lethal concentrations of antibiotics narrowly limits our perspective of antibiotic resistance evolution. New high-resolution competition assays have shown that resistant bacteria are selected at relatively low concentrations of antibiotics. This finding is important because sublethal concentrations of antibiotics are found widely in patients undergoing antibiotic therapies, and in nonmedical conditions such as wastewater treatment plants, and food and water used in agriculture and farming. To understand the impacts of sublethal concentrations on selection, we measured 30 adaptive landscapes for a set of TEM β-lactamases containing all combinations of the four amino acid substitutions that exist in TEM-50 for 15 β-lactam antibiotics at multiple concentrations. We found that there are many evolutionary pathways within this collection of landscapes that lead to nearly every TEM-genotype that we studied. While it is known that the pathways change depending on the type of β-lactam, this study demonstrates that the landscapes including fitness optima also change dramatically as the concentrations of antibiotics change. Based on these results we conclude that the presence of multiple concentrations of β-lactams in an environment result in many different adaptive landscapes through which pathways to nearly every genotype are available. Ultimately this may increase the diversity of genotypes in microbial populations. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Antibiotic resistance profile and phenotypic detection of beta ...

African Journals Online (AJOL)

Abstract. Background: Cockroaches are carriers of numerous microorganisms. However, there is paucity of information on their role as potential reservoir for beta-lactamase producers. Objectives: This research determined the antibiotics susceptibility profile of Beta-lactamase producing Gram-negative bacteria isolated from ...

Functional Characterization of Bacteria Isolated from Ancient Arctic Soil Exposes Diverse Resistance Mechanisms to Modern Antibiotics

Science.gov (United States)

Perron, Gabriel G.; Whyte, Lyle; Turnbaugh, Peter J.; Goordial, Jacqueline; Hanage, William P.; Dantas, Gautam; Desai, Michael M.

2015-01-01

Using functional metagenomics to study the resistomes of bacterial communities isolated from different layers of the Canadian high Arctic permafrost, we show that microbial communities harbored diverse resistance mechanisms at least 5,000 years ago. Among bacteria sampled from the ancient layers of a permafrost core, we isolated eight genes conferring clinical levels of resistance against aminoglycoside, β-lactam and tetracycline antibiotics that are naturally produced by microorganisms. Among these resistance genes, four also conferred resistance against amikacin, a modern semi-synthetic antibiotic that does not naturally occur in microorganisms. In bacteria sampled from the overlaying active layer, we isolated ten different genes conferring resistance to all six antibiotics tested in this study, including aminoglycoside, β-lactam and tetracycline variants that are naturally produced by microorganisms as well as semi-synthetic variants produced in the laboratory. On average, we found that resistance genes found in permafrost bacteria conferred lower levels of resistance against clinically relevant antibiotics than resistance genes sampled from the active layer. Our results demonstrate that antibiotic resistance genes were functionally diverse prior to the anthropogenic use of antibiotics, contributing to the evolution of natural reservoirs of resistance genes. PMID:25807523

Concentric resistance training increases muscle strength without affecting microcirculation

Energy Technology Data Exchange (ETDEWEB)

Weber, Marc-Andre [Department of Diagnostic and Interventional Radiology, University of Heidelberg, Heidelberg (Germany)], E-mail: MarcAndre.Weber@med.uni-heidelberg.de; Hildebrandt, Wulf [Immunochemistry, German Cancer Research Center (dkfz), Heidelberg (Germany); Schroeder, Leif [Medical Physics in Radiology, German Cancer Research Center (dkfz), Heidelberg (Germany); Kinscherf, Ralf [Department of Anatomy and Developmental Biology, University of Heidelberg, Heidelberg (Germany); Krix, Martin [Radiology, German Cancer Research Center (dkfz), Heidelberg (Germany); Bachert, Peter [Medical Physics in Radiology, German Cancer Research Center (dkfz), Heidelberg (Germany); Delorme, Stefan; Essig, Marco [Radiology, German Cancer Research Center (dkfz), Heidelberg (Germany); Kauczor, Hans-Ulrich [Department of Diagnostic and Interventional Radiology, University of Heidelberg, Heidelberg (Germany); Krakowski-Roosen, Holger [National Center for Tumor Diseases (NCT), Heidelberg (Germany)

2010-03-15

Purpose: While the evidence is conclusive regarding the positive effects of endurance training, there is still some controversy regarding the effects of resistance training on muscular capillarity. Thus, the purpose was to assess whether resistance strength training influences resting skeletal muscle microcirculation in vivo. Materials and methods: Thirty-nine middle-aged subjects (15 female, 24 male; mean age, 54 {+-} 9 years) were trained twice a week on an isokinetic system (altogether 16 sessions lasting 50 min, intensity 75% of maximum isokinetic and isometric force of knee flexors and extensors). To evaluate success of training, cross-sectional area (CSA) of the quadriceps femoris muscle and its isokinetic and isometric force were quantified. Muscular capillarization was measured in biopsies of the vastus lateralis muscle. In vivo, muscular energy and lipid metabolites were quantified by magnetic resonance spectroscopy and parameters of muscular microcirculation, such as local blood volume, blood flow and velocity, by contrast-enhanced ultrasound analyzing replenishment kinetics. Results: The significant (P < 0.001) increase in CSA (60 {+-} 16 before vs. 64 {+-} 15 cm{sup 2} after training) and in absolute muscle strength (isometric, 146 {+-} 44 vs. 174 {+-} 50 Nm; isokinetic, 151 {+-} 53 vs. 174 {+-} 62 Nm) demonstrated successful training. Neither capillary density ex vivo (351 {+-} 75 vs. 326 {+-} 62) nor ultrasonographic parameters of resting muscle perfusion were significantly different (blood flow, 1.2 {+-} 1.2 vs. 1.1 {+-} 1.1 ml/min/100 g; blood flow velocity, 0.49 {+-} 0.44 vs. 0.52 {+-} 0.74 mm s{sup -1}). Also, the intensities of high-energy phosphates phosphocreatine and {beta}-adenosintriphosphate were not different after training within the skeletal muscle at rest ({beta}-ATP/phosphocreatine, 0.29 {+-} 0.06 vs. 0.28 {+-} 0.04). Conclusion: The significant increase in muscle size and strength in response to concentric isokinetic and isometric

Frequency of the Occurence of Methicilin Resistant Staphylococcus aureus (MRSA Infections in Hyderabad, Pakistan

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Nazir Ahmed Brohi

2017-06-01

Full Text Available Staphylococcus aureus is a potential pathogen of hospital and community related infections. It secretes toxins or the enzymes as virulence factor of mild to severe infections and show resistance to beta-lactam antibiotic including penicillin, methicillin, oxacillin and now vancomycin that could alarm of equal risk factors of Methicillin Resistant Staphylococcus aureus (MRSA infections in the patients. The survey report of 381 patients of Hyderabad, Pakistan was collected from March 2013 to June 2014 in which 176 cases were reported for Staphylococcus aureus in both genders of different age groups of 3-15 y kids, 16-45 y adults and 45-70 y olds, which showed 208 and 132 specimens Staphylococcus infection and 16 and 4 cases of MRSA infections in male and female patients, respectively whereas other 31 cases showed no infection. The laboratory diagnosis of the 200 samples from various hospitalized patients revealed the highest percentage of Methicillin Resistant Staphylococcus aureus MRSA in pus and post-operative wounds (17% followed by skin swabs (10%, sputum (7% and blood (0%. The observations revealed greater prevalence of MRSA infection in elderly age 16-45 years males than the females and other age groups. Antibiotic susceptibility test of 26 antibiotics revealed resistance (R-53%, sensitive (S-39 and variable (V-7% sensitivity zones (mm. Amplification of mecA gene was done using PCR reaction that revealed mecA gene bands up to 150-200 base pairs by test resistant strains.

Identification, antimicrobial resistance and genotypic characterization of Enterococcus spp. isolated in Porto Alegre, Brazil

Science.gov (United States)

Bender, Eduardo André; de Freitas, Ana Lúcia Peixoto; Reiter, Keli Cristine; Lutz, Larissa; Barth, Afonso Luís

2009-01-01

In the past two decades the members of the genus Enterococcus have emerged as important nosocomial pathogens worldwide. In the present study, we evaluated the antimicrobial resistance and genotypic characteristics of 203 Enterococcus spp. recovered from different clinical sources from two hospitals in Porto Alegre, Rio Grande do Sul, Brazil. The species were identified by conventional biochemical tests and by an automated system. The genetic diversity of E. faecalis presenting high-level aminoglycoside resistance (HLAR) was assessed by pulsed-field gel electrophoresis of chromosomal DNA after SmaI digestion. The E. faecalis was the most frequent specie (93.6%), followed by E. faecium (4.4%). The antimicrobial resistance profile was: 2.5% to ampicillin, 0.5% to vancomycin, 0.5% teicoplanin, 33% to chloramphenicol, 2% to nitrofurantoin, 66.1% to erythromycin, 66.5% to tetracycline, 24.6% to rifampicin, 30% to ciprofloxacin and 87.2% to quinupristin-dalfopristin. A total of 10.3% of the isolates proved to be HLAR to both gentamicin and streptomycin (HLR-ST/GE), with 23.6% resistant only to gentamicin (HLR-GE) and 37.4% only to streptomycin (HLR-ST). One predominant clonal group was found among E. faecalis HLR-GE/ST. The prevalence of resistance among beta-lactam antibiotics and glycopeptides was very low. However, in this study there was an increased number of HLR Enterococcus which may be spreading intra and inter-hospital. PMID:24031416

Simple and suitable immunosensor for β-lactam antibiotics analysis in real matrixes: milk, serum, urine.

Science.gov (United States)

Merola, Giovanni; Martini, Elisabetta; Tomassetti, Mauro; Campanella, Luigi

2015-03-15

The anti-penicillin G was conjugated to avidin-peroxidase and biotin to obtain immunogen and competitor which were then used to develop a competitive immunosensor assay for the detection of penicillin G and other β-lactam antibiotics, with Kaff values of the order of 10(8) M(-1). The new immunosensor appears to afford a number of advantages in terms of sensitivity, possibility of "in situ" analysis, but especially of simplicity and lower costs, compared with other existing devices, or different chemical instrumental methods reported in the literature and used for the analysis of β-lactam compounds. Satisfactory results were found in the analysis of real matrixes and good recoveries were obtained by applying the standard addition method to spiked milk, urine, serum and drug samples. The new device uses an amperometric electrode for hydrogen peroxide as transducer, the BSA-penicillin G immobilized on polymeric membrane overlapping the amperometric transducer and the peroxidase enzyme as marker. It proved to be highly sensitive, inexpensive and easily reproducible; LOD was of the order of 10(-11)M. Lastly, the new immunosensor displayed low selectivity versus the entire class of β-lactam antibiotics and higher selectivity toward other classes of non-β-lactam antibiotics. Copyright © 2014 Elsevier B.V. All rights reserved.

Beta-Lactam Antibiotic Sensitization and Its Relationship to Allergic Diseases in Tertiary Hospital Nurses

Science.gov (United States)

Han, Eui-Ryoung; Lim, Seong-Wook; Lim, Seong-Ryoon; Kim, Ji-Na; Park, Sin-Young; Chae, Su-Kyoung; Lim, Hye-Hyeun; Seol, Young-Ae; Bae, You-In; Won, Young-Ho

2010-01-01

Purpose Skin allergies through type 1 and 4 hypersensitivity reactions are the most frequent manifestations of drug allergies. We had previously experienced a case of a nurse with cefotiam-induced contact urticaria syndrome. To aid in preventing the progression of drug-induced allergic disease in nurses, we conducted a survey of tertiary hospital nurses who were likely to have been exposed professionally to antibiotics. Methods All 539 staff nurses at a tertiary hospital were asked to respond to a questionnaire regarding antibiotic exposure. Of the 457 nurses (84.8%) who responded, 427 (79.2%) received a physical examination of the hands and 318 (59.0%) received skin prick tests with the β-lactam antibiotics cefotiam, cefoperazone, ceftizoxime, flomoxef, piperacillin and penicillin G. Results A positive response to at least one of the antibiotics occurred in 8 (2.6%) of the 311 subjects included in the analysis and stages 1 and 2 contact urticaria syndrome were observed in 38 (8.9%) and 3 (0.7%) of 427 nurses, respectively. The frequencies of a positive antibiotic skin test (6.9 versus 1.3%, χ2=7.15, P=0.018), stage 1 contact urticaria syndrome (14.4 versus 7.4%, χ2=4.33, P=0.038) and drug allergy (15.3 versus 3.6%, χ2=18.28, P=0.000) were higher in subjects with a positive skin allergy history than in those without. Allergic rhinitis (P=0.02, OR=3.86, CI=1.23-12.06), night cough (P=0.04, OR=3.12, CI=1.03-9.41) and food allergy (P=0.00, OR=9.90, CI=3.38-29.98) were significant risk factors for drug allergy. Conclusions Antibiotic sensitization and drug allergy occurred more frequently in nurses with a positive skin allergy history. Atopy may be an important risk factor for drug allergy. PMID:20358025

Evaluation of frictional resistance between monocrystalline (ICE brakcets and Stainless Steel, Beta TMA and NiTiarch wires

Directory of Open Access Journals (Sweden)

Meysam Mirzaie

2013-09-01

Full Text Available Introduction: When using sliding mechanics for space closure during orthodontic treatment, friction occurs at the bracket-wire interface. The aim of this study was to evaluate the frictional resistance between monocrystalline (ICE brackets and Stainless Steel, Beta TMA and NiTi wires. Methods: In this experimental study, we used 5 different types of orthodontic wires. Brackets and wires were divided in to 5 groups: 1-(monocrystalline+stainless steel 18 2–(monocrystalline+stainless steel 19×25 3-(monocrystalline+Beta-TMA 4–(monocrystalline+Beta TMA 19×25 5-(monocrystalline+NiTi 18. Instron Universal Testing Machine was used to investigate the static frictional resistance. The angulation between bracket and wire was 0 and the wires were pulled through the slots at a speed of 10 mm/min. Tests were performed 10 times for each group in artificial saliva. The average of 10 forces recorded was considered as static friction. One-way ANOVA and SPSS Version 18 and LSD post hoc test were used to evaluate the results of the study. Results: The mean static frictional force for each group was: group1: 0.82 ± 0.14, group 2: 1.09 ± 0.30, group 3: 0.87 ± 0.53, group 4: 1.9 ± 1.16, group 5: 1.42 ± 0.30. There was a significant difference when comparing the two groups of similar wires in terms of shape (round or rectangular cross-section as when comparing Beta TMA 18 and 19×25 arch wires with each other, the obtained p-value was 0.023, while the obtained p-value for the comparison of stainles steel arch wires was 0.034 . Conclusions: The result of this study shows that Stainless Steel 18 wires generate the least amount of friction and round wires produce less friction than the rectangular wires. Beta TMA wires generate the highest amount of friction.

Heavy metals in liquid pig manure in light of bacterial antimicrobial resistance

International Nuclear Information System (INIS)

Hölzel, Christina S.; Müller, Christa; Harms, Katrin S.; Mikolajewski, Sabine; Schäfer, Stefanie; Schwaiger, Karin; Bauer, Johann

2012-01-01

Heavy metals are regularly found in liquid pig manure, and might interact with bacterial antimicrobial resistance. Concentrations of heavy metals were determined by atomic spectroscopic methods in 305 pig manure samples and were connected to the phenotypic resistance of Escherichia coli (n=613) against 29 antimicrobial drugs. Concentrations of heavy metals (/kg dry matter) were 0.08–5.30 mg cadmium, 1.1–32.0 mg chrome, 22.4–3387.6 mg copper, <2.0–26.7 mg lead, <0.01–0.11 mg mercury, 3.1–97.3 mg nickel and 93.0–8239.0 mg zinc. Associated with the detection of copper and zinc, resistance rates against β-lactams were significantly elevated. By contrast, the presence of mercury was significantly associated with low antimicrobial resistance rates of Escherichia coli against β-lactams, aminoglycosides and other antibiotics. Effects of subinhibitory concentrations of mercury on bacterial resistance against penicillins, cephalosporins, aminoglycosides and doxycycline were also demonstrated in a laboratory trial. Antimicrobial resistance in the porcine microflora might be increased by copper and zinc. By contrast, the occurrence of mercury in the environment might, due to co-toxicity, act counter-selective against antimicrobial resistant strains.

[Distribution and removal of anaerobic antibiotic resistant bacteria during mesophilic anaerobic digestion of sewage sludge].

Science.gov (United States)

Tong, Juan; Wang, Yuan-Yue; Wei Yuan, Song

2014-10-01

Sewage sludge is one of the major sources that releasing antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARG) into the environment since it contains large amount of ARB, but there is little information about the fate of the anaerobic ARB in the anaerobic digestion of sewage sludge. Therefore, the distribution, removal and seasonal changes of tetracycline and β-lactam antibiotics resistant bacteria in the mesophilic egg-shaped digesters of a municipal wastewater treatment plant were investigated for one year in this study. Results showed that there were higher amounts of ARB and higher resistance rate of β-lactam antibiotics than that of tetracycline antibiotics in the sewage sludge. All ARB could be significantly reduced during the mesophilic anaerobic digestion process by 1.48-1.64 log unit (P anaerobic digestion by 12.0% and 14.3%, respectively (P bacteria, there were more ARB in the sewage sludge in cold season than in warm season (P < 0.05).