A gene (bla) encoding a beta-lactamase is present in the cephamycin gene cluster of Streptomyces clavuligerus, the strain producing clavulanic acid and a beta-lactamase inhibitory protein. The bla gene is located 5.1 kb downstream from and in the opposite orientation to cefE, encoding the deacetoxycephalosporin C synthase. The bla gene encodes a 332-residue protein (Mr, 35,218), similar to othe...

The active-site serine of the extracellular beta-lactamases of Streptomyces cacaoi and Streptomyces albus G has been labelled with beta-iodopenicillanate. The determination of the sequence of the labelled peptides obtained after trypsin digestion of the denatured proteins indicate both enzymes to be class A beta-lactamases. Surprisingly the two Streptomyces enzymes do not appear to be especiall...

A detailed kinetic study of the interactions between BRL 42715, a beta-lactamase-inhibiting penem, and various beta-lactamases (EC 3.5.2.6) and D-alanyl-D-alanine peptidases (DD-peptidases, EC 3.4.16.4) is presented. The compound was a very efficient inactivator of all active-site serine beta-lactamases but was hydrolyzed by the class B, Zn(2+)-containing enzymes, with very different kcat value...

The objective of this study was to investigate the trends and patterns of resistance in beta-lactamase-producing members of the family Enterobacteriaceae in a children's hospital over a 9-year period (1999 to 2007). Clinically significant isolates of the Enterobacteriaceae were screened for patterns of broad-spectrum resistance to beta-lactams. The strains likely to be resistant were subsequent...

To determine the prevalence and genotype of an extended-spectrum beta-lactamase and new chromosomal AmpC beta-lactamases among clinical isolates of Enterobacter species, we performed antibiotic susceptibility testing, pI determination, induction tests, transconjugation, enterobacterial repetitive consensus (ERIC) PCR, sequencing, and phylogenetic analysis. Among the 51 clinical isolates collect...

Enterobacterial strains of Raoultella spp. display a penicillinase-related beta-lactam resistance pattern suggesting the presence of a chromosomal bla gene. From whole-cell DNA of Raoultella planticola strain ATCC 33531(T) and Raoultella ornithinolytica strain ATCC 31898(T), bla genes were cloned and expressed into Escherichia coli. Each gene encoded an Ambler class A beta-lactamase, named PLA-...

Klebsiella pneumoniae strain 11978 was isolated in Turkey in 2001 and was found to be resistant to all beta-lactams, including carbapenems. Cloning and expression in Escherichia coli identified five beta-lactamases, including two novel oxacillinases. The beta-lactamase OXA-48 hydrolyzed imipenem at a high level and was remotely related (less than 46% amino acid identity) to the other oxacillina...