The Oxoid combination disk method for detecting extended-spectrum beta-lactamases (ESBLs) depends on comparing the inhibition zones of cefpodoxime (10-microg) and cefpodoxime-plus-clavulanate (10- plus 1-microg) disks. The presence of clavulanate enlarged the zones for all of 180 ESBL-producing klebsiellae by >/=5 mm, whereas zones for cefpodoxime-susceptible isolates and cefpodoxime-resistant ...

Biapenem, formerly LJC 10,627 or L-627, a carbapenem antibiotic, was studied in its interactions with 12 beta-lactamases belonging to the four molecular classes proposed by R. P. Ambler (Philos. Trans. R. Soc. Lond. Biol. Sci. 289:321-331, 1980). Kinetic parameters were determined. Biapenem was readily inactivated by metallo-beta-lactamases but behaved as a transient inhibitor of the active-sit...

Despite the recent global spread of CTX-M beta-lactamases in Escherichia coli isolates from community-acquired urinary tract infections (CA-UTIs), their dissemination has been little studied in developing countries. In a 2-year prospective study, we documented the prevalence of extended-spectrum beta-lactamases (ESBLs) in E. coli that were responsible for CA-UTIs in Phnom-Penh, Cambodia. Ninety...

The beta-lactamase specified by an R(te16) plasmid in Bordetella bronchiseptica was purified 200-fold by carboxymethyl-Sephadex column chromatography and electrofocusing. The enzyme has a molecular weight of 46,000 +/- 3,000 and an isoelectric point of 8.3 and was highly active against phenethicillin, oxacillin, and propicillin. The enzyme activity was inhibited by sodium chloride but not by fe...

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...

The β-lactamases enzymes cleave the amide bond in β-lactam ring, rendering β-lactam antibiotics harmless to bacteria. In this communication we have studied structure-function relationship and phylogenies of class A, B and D beta-lactamases using structure-based sequence alignment and phylip programs respectively. The data of structure-based sequence alignment suggests that in different isolates...

Hydrolysis of beta-lactam antibiotics by beta-lactamase enzymes is the most common mechanism of bacterial resistance to these agents. Several small-molecule, mechanism-based inhibitors of beta-lactamases such as clavulanic acid are clinically available although resistance to these inhibitors has been increasing in bacterial populations. In addition, these inhibitors act only on class A beta-lac...

Imipenem has excellent antimicrobial activity owing in part to beta-lactamase stability. We found that only 2 of over 350 Bacteroides fragilis group clinical isolates were resistant to imipenem, with an MIC of more than 16 micrograms/ml. These two isolates from the Tufts Anaerobe Laboratory (TAL) were resistant to all other beta-lactam agents tested. The organisms were able to inactivate imipen...

Bacteroides fragilis CS30 is a clinical isolate resistant to high concentrations of benzylpenicillin and cephaloridine but not to cephamycin or penem antibiotics. beta-Lactam resistance is mediated by a chromosomally encoded cephalosporinase produced at a high level. The gene encoding this beta-lactamase was cloned from genomic libraries constructed in Escherichia coli and then mated with B. fr...