A functional classification scheme for beta-lactamases and its correlation with molecular structure

Bush, Karen; Jacoby, George A.; Medeiros, A A

doi:10.1128/aac.39.6.1211

Cited by 2,225 publications

(1,876 citation statements)

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“…Resistance to β-lactam antibiotics is mainly mediated by a large number of β-lactamases which differ in their abilities to hydrolyse the various β-lactam antibiotics [2,9,38,71]. Other resistance mechanisms include the acquisition of penicillinbinding proteins (PBPs) with reduced affinity to β-lactams, mutations in the PBPs [24,26], but also reduced β-lactam uptake due to alterations in the outer membrane of gramnegative bacteria or export by multidrug transporters [44,48].…”

Section: Resistance To β-Lactam Antibioticsmentioning

confidence: 99%

“…Enzymatic inactivation of β-lactam antibiotics is achieved by β-lactamases [2,9,38,71]. On the basis of their substrate spectra and their inhibition by clavulanic acid (CA), β-lactamases are classified into at least four classes (1-4), one of which, class 2, consists of eight subclasses [9].…”

Section: Resistance To β-Lactam Antibioticsmentioning

confidence: 99%

“…On the basis of their substrate spectra and their inhibition by clavulanic acid (CA), β-lactamases are classified into at least four classes (1-4), one of which, class 2, consists of eight subclasses [9]. It is noteworthy that single amino acid exchanges may result in changes of the substrate spectrum.…”

Section: Resistance To β-Lactam Antibioticsmentioning

confidence: 99%

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Use of antimicrobials in veterinary medicine and mechanisms of resistance

2001

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-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, β-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.antibiotic therapy / growth promotion / resistance mechanism / resistance gene / gene transfer Résumé -Utilisation d'agents antimicrobiens en médecine vétérinaire et mécanismes de résis-tance. Cette revue présente les différents buts pour lesquels les agents antimicrobiens sont utilisés en médecine vétérinaire, dans les élevages d'animaux entrant dans la chaîne alimentaire et les possibles conséquences de cette large utilisation. Une synthèse est faite des différents mécanismes de résis-tance développés par les bactéries, comme l'inactivation enzymatique, la diminution de la concentration intracellulaire de l'antibiotique, les modification/protection/déplacement de cible, qui permettent d'échapper à l'action des antibiotiques les plus fréquemment utilisés dans le domaine vétérinaire :

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Section: Resistance To β-Lactam Antibioticsmentioning

confidence: 99%

Section: Resistance To β-Lactam Antibioticsmentioning

confidence: 99%

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Use of antimicrobials in veterinary medicine and mechanisms of resistance

2001

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“…Emergence of plasmid-mediated AmpC b-lactamase producing strains is well recognized [6][7][8]. Phenotypically bacteria resemble chromosomal class C b-lactamase producers in that they confer resistance to cephalosporins and cephamycins such as, cefoxitin, and are not inhibited by b-lactam/b-lactamase inhibitors [9].…”

Section: Introductionmentioning

confidence: 99%

Occurrence of Plasmid-Mediated AmpC β-Lactamases Among Escherichia coli and Klebsiella pneumoniae Clinical Isolates in a Tertiary Care Hospital in Bangalore

Sasirekha

Shivakumar

2011

Indian J Microbiol

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Therapeutic options for infections caused by gram-negative organisms expressing plasmid-mediated AmpC b-lactamases are limited because these organisms are usually resistant to all the b-lactam antibiotics, except for cefepime, cefpirome and the carbapenems. These organisms are a major concern in nosocomial infections and should therefore be monitored in surveillance studies. Hence, this study was aimed out to determine the prevalence of plasmid-mediated AmpC b-lactamases in E. coli and K. pneumoniae from a tertiary care in Bangalore. A total of 63 E. coli and 27 K. pneumoniae were collected from a tertiary care hospital in Bangalore from February 2008 to July 2008. The isolates with decreased susceptibility to cefoxitin were subjected to confirmation test with three dimensional extract tests. Minimum inhibitory concentrations (MICs) were determined by agar dilution method. Conjugation experiments, plasmid profiling and susceptibility testing were carried out to investigate the underlying mechanism of resistance. In our study, 52 (57.7%) isolates showed resistance to cefoxitin, the occurrence of AmpC was found to be 7.7% of the total isolates. Plasmid analysis of the selected isolates showed the presence of a single plasmid of 26 kb in E. coli and 2 Kb in K. pneumoniae. Plasmid-mediated AmpC b-lactamases were found in 11.1% of K. pneumoniae and in 6.3% of E. coli. Curing and conjugation experiments showed that resistance to cephamycins and cephalosporins was plasmid-mediated. Our study has demonstrated the occurrence of plasmid-mediated AmpC in E. coli and K. pneumoniae which illustrates the importance of molecular surveillance in tracking AmpC-producing strains at general hospitals and emphasizes the need for epidemiological monitoring.

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“…To date, more than 100 different SHV-type β-lactamases have been described which differ at one or more amino acid positions (www.lahey.org/studies). Originally, the SHV-1 β-lactamase, first described by Pitton in 1972 as Pit-2 [2], was considered to be a plasmid-encoded enzyme, belonging to class A, group 2b β-lactamases [3]. However, using more sensitive nucleic acid-based assays, the chromosomal location of the SHV-1 gene in all K. pneumoniae isolates could be demonstrated but not in Klebsiella oxytoca isolates [4][5][6].…”

Section: Introductionmentioning

confidence: 99%