β-lac·ta·mase

(lak'tă-mās),

An enzyme produced by many species of bacteria that disrupts the four-membered β-lactam ring of penicillin and cephalosporin groups of antibiotics, destroying their antimicrobial activity. The ability of an organism to produce a β-lactamase may be chromosomal and constitutive or a plasmid-associated acquired property.

Synonym(s): cephalosporinase, lactamase, penicillinase (1)

Farlex Partner Medical Dictionary © Farlex 2012

beta-lactamase

(bā′tə-lăk′tə-mās′, -māz′, bē′-)

Any of various enzymes that hydrolyze and inactivate beta-lactam antibiotics such as penicillin, found in many antibiotic-resistant bacteria.

be·ta-lac·ta·mase

(bā'tă lak'tā-mās)

Medical Dictionary for the Dental Professions © Farlex 2012

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References in periodicals archive

Acknowledgement: We are grateful to MD Burcin Sener, of Hacettepe University Medical Faculty, Department of Medical Microbiology, Ankara, Turkey, for providing plasmid-mediated AmpC beta-lactamase positive control isolates.

Investigation of plasmid mediated AmpC beta-lactamases in Escherichia coli and Klebsiella pneumoniae isolates by phenotypic and genotypic

Carbapenem resistance and acquired class D beta-lactamases in Acinetobacter baumannii from Croatia 2009-2010.

FALSE POSITIVE PHENOTYPIC DETECTION OF METALLO-BETA-LACTAMASES IN ACINETOBACTER BAUMANNII

Class A, and D beta-lactamases all share a serine residue in the active site, while class B enzymes require the presence of zinc for activity (and hence are referred to as metallo-beta-lactamases).

DISSEMINATION AND DETECTION OF CARBAPENEMASES PRODUCING GRAM-NEGATIVE RODS

(11,12) Extended-spectrum beta-lactamase producers were primerly isolated from the female medical ward (20.2%), male surgical ward (17.7%), and male medical ward and female surgical ward (13.4%) and ICU (12.3%).

Risk factors and molecular features of extended-spectrum beta-lactamase producing bacteria at southwest of Saudi Arabia

However, on genotypic detection, beta-lactamases were observed in 15.6% (n=5), 6.2% (n=2), 3.1% (n=1) and 28.1% (n=9) isolates showing presence of [bla.sub.CTX-M], [bla.sub.TEM], [bla.sub.SHV] and [bla.sub.ampC] genes, respectively.

Co-occurrence of extended-spectrum- and AmpC-[beta]-lactamase-encoding genes in Enterobacteriaceae isolated from sewage and drinking water from North-India: analyzing the genetic environment with special reference to insertion sequences, integrase, and integrons

Emergence of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae in Danish hospitals; this is in part explained by spread of two CTX-M-15 clones with multilocus sequence types 15 and 16 in Zealand.

Prevalence of [bla.sub.CTX-M] Gene among Extended-Spectrum [beta]-Lactamases Producing Klebsiella pneumoniae Clinical Isolates in Iran: A Meta-Analysis

(4,5) The production of some MDR enzymes such as extendedspectrum beta-lactamases (ESBLs) by gram-negative bacteria can be masked by the coexpression of AmpC in the same organism.

First Detection of FOX-1 AmpC [beta]-lactamase Gene Expression Among Escherichia coli Isolated from Abattoir Samples in Abakaliki, Nigeria

The ratio of extended spectrum beta-lactamase production and antibiotic resistance in Escherichia coli and Klebsiella pneumoniae.

Evaluation of Antimicrobial Resistance Rates in Klebsiella Isolates/Klebsiella Izolatlarinin Antimikrobiyal Direnc Oranlarinin Degerlendirilmesi

Duo et al., "DHA-1 plasmid-mediated AmpC beta-lactamase expression and regulation of Klebsiella pnuemoniae isolates," Molecular Medicine Reports, vol.

The Structure of ampG Gene in Pseudomonas aeruginosa and Its Effect on Drug Resistance

Results were interpreted according to the guidelines of Clinical and Laboratory Standards Institute (CLSI), where interpretive criteria for ESBL activity were based on an increase of more than 5 mm in the diameter of the inhibition zone around disks containing clavulanic acid as compared to the diameters of the inhibition zone around disks free of this beta-lactamase inhibitor [18].

Prevalence of Extended-Spectrum Beta-Lactamases-Producing Microorganisms in Patients Admitted at KRRH, Southwestern Uganda

Boronic acid can be used as AmpC beta-lactamase inhibitor.4 Multidrug resistance can be avoided by the restricted use of third-generation cephalosporins in neonatal sepsis.6

Detection of AmpC b-lactamase producing bacteria isolated in neonatal sepsis

Phenotypic detection of extended-spectrum beta-lactamase production in Enterobacteriaceae: review and bench guide.

Detection and molecular characterization of [beta]-lactamase genes in clinical isolates of Gram-negative bacteria in Southern Ecuador