Pseudomonas aeruginosa produces a low basal level of beta-lactamase (0.002 to 0.004 IU/mg of protein when benzylpenicillin is used as substrate). The beta-lactamase specific activity can be increased several hundredfold by growing the bacteria in the presence of beta-lactam antibiotics. This induction was studied in Pseudomonas aeruginosa 1822s. The single-cell resistance to benzylpenicillin wa...

A temperature-sensitive mutant, strain SS, which is assumed to be devoid of beta-lactamase activity and deficient in a permeability barrier to antibiotics, was isolated from a beta-lactamase-less mutant, strain L-2, derived from Pseudomonas aeruginosa IFO 3080. By comparing the beta-lactam antibiotic susceptibility between strains IFO 3080, L-2, and SS, the involvement of both beta-lactamase an...

Vaborbactam (formerly RPX7009) is a new beta-lactamase inhibitor based on a cyclic boronic acid pharmacophore. The spectrum of beta-lactamase inhibition by vaborbactam and the impact of bacterial efflux and permeability on its activity were determined using a panel of strains with beta-lactamases cloned from various classes and a panel of Klebsiella pneumoniae carbapenemase 3 (KPC-3)-producing ...

The gene, cblA, encoding the species-specific, clavulanate-susceptible, endogenous cephalosporinase was cloned from Bacteroides uniformis WAL-7088. The nucleotide sequence was determined, and the cblA structural gene was found to be 891 nucleotides, with a 48% G+C composition, which is similar to that of the B. uniformis genome. The cblA open reading frame encoded an Ambler class A beta-lactama...

Staphylococcus aureus produces four types of beta-lactamase (A, B, C, and D). To investigate the effect of specific beta-lactamase type upon staphylococcal resistance, each beta-lactamase was purified to homogeneity, and the Michaelis constants (Km values) and turnover numbers (kcat values) for various penicillin and cephalosporin substrates were determined. Whereas Km values of the four beta-l...

The chromogenic cephalosporin nitrocefin was used to detect the presence of beta-lactamase in cerebrospinal fluid of patients suffering from ampicillin-resistant Haemophilus influenzae meningitis. Five samples of spinal fluid containing ampicillin-resistant isolates were studied, and all had beta-lactamase activity. When samples of spinal fluid containing 33 ampicillin-sensitive isolates and 23...

Canadian invasive Haemophilus influenzae isolates from 1990 to 2006 were examined for antibiotic susceptibility: 42 strains (17.8%) were resistant to ampicillin by beta-lactamase production, 5.5% were beta-lactamase negative ampicillin intermediate, and 2.5% were intermediate to only the 2-microg ampicillin disk. An increase in beta-lactamase-negative ampicillin-intermediate strains has been fo...

Background & objective: Beta-lactam antibiotics resistance specifically Imipenem and Meropenem, the last choices of treatment, causes fatal events in patients with P.aeruginosa infection. The aim of this study was to detect the VIM and IMP of metallo-beta-lactamase genes in 103 isolates of P. aeruginosa in two Iranian hospitals. <strong...