Two clinical isolates of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae were noted to be less susceptible than expected to imipenem. Both were missing outer membrane proteins that serve as channels for antibiotic entry. The role of beta-lactamase in resistance was investigated by eliminating the original ESBL and introducing plasmids encoding various ESBLs and AmpC beta...

Previous studies have reported beta-lactamase-mediated penicillin resistance in Fusobacterium nucleatum, but no beta-lactamase gene has yet been identified in this species. An F. nucleatum subsp. polymorphum strain resistant to penicillin and amoxicillin was isolated from a human periodontitis sample. DNA cloning and sequencing revealed a 765-bp open reading frame encoding a new class D beta-la...

Synthesis and secretion of beta-lactamase were studied in Salmonella typhimurium infected with P22 phage carrying the structural gene for beta-lactamase (the bla gene) in mutant or wild-type form. The wild-type gene was shown to specify two forms of beta-lactamase which differ in molecular weight by about 2500 daltons. This difference is consistent with removal, predicted on other grounds, of 2...

The gene encoding BLIP, a beta-lactamase-inhibitory protein, was disrupted in wild-type Streptomyces clavuligerus and in a clavulanic acid non-producing mutant. The resulting BLIP mutant and BLIP/clavulanic acid double mutant showed no residual proteinaceous beta-lactamase-inhibitory activity, indicating that only a single beta-lactamase-inhibitory protein exists in S. clavuligerus. The lack of...

BACKGROUND & OBJECTIVES AmpC beta-lactamases are Group I cephalosporinases that confer resistance to a wide variety of beta-lactam drugs. Plasmid mediated AmpC beta-lactamases has been discovered most frequently in isolates of Klebsiella pneumoniae, K. oxytoca, Salmonella, Proteus mirabilis and Escherichia coli. The present study was undertaken to study the occurrence of multidrug resistant and...

the nosocomial infections, caused by multi-drug resistant bacteria, are the most important cause of mortality throughout the world. one important mechanism against beta-lactam antibiotics is the production of beta-lactamases. enterobacteriaceae and non-fermentative bacteria, like pseudomonas aeruginosa and acinetobacter baumannnii may produce these enzymes. currently, there is no vaccine to pre...

conclusions despite of high resistance of p. aeruginosa, the resistance rate of p. aeruginosa strains isolated from children in the current study was not high. then accurate prescription of antibiotics can decrease the speed of resistance creation. background the first report of pseudomonas aeruginosa (p. aeruginosa) carbapenem resistant strains, and especially the metallo-beta-lactam (mbl) pro...

conclusions regarding the importance of metallo-beta-lactamase (mbl) produced by pseudomonas spp. isolated from hospitals, quick identification of clinical samples should be considered as an important and basic step to treat and control infections caused by pseudomonas spp. results strains with mic > 4 µg/ml were investigated by phenotypic and genotypic methods. in the current study the rate of...