Extended-spectrum beta-lactamases (ESBLs) are widespread in hospital settings worldwide. The present investigation was undertaken to assess the distribution and prevalence of ESBLs belonging to the TEM and SHV families in 448 ESBL-producing clinical isolates of Enterobacteriaceae collected from 10 different Italian hospitals. The natures of TEM and SHV determinants were identified by direct seq...

Extended-spectrum beta-lactamases (ESBLs), e.g., ESBLs of the TEM or SHV type, compromise the efficacies of expanded-spectrum cephalosporins. An SHV non-ESBL that hydrolyzes only narrow-spectrum cephalosporins can be converted into an SHV ESBL through substitutions at three amino acid positions, 179, 238, or 238--240. In order to improve detection of SHV ESBLs, a novel method, based on real-tim...

Nucleotide sequencing is the standard molecular method for determination of the beta-lactamase gene present in an isolate. Using minimal sequence quality values prevents misidentification of bla(SHV) genes, as illustrated by three strains of three different species that each contained two different bla(SHV) alleles, SHV-2 and SHV-12.

A clinical strain of Klebsiella pneumoniae was found to possess the chromosomal gene bla(SHV-56), encoding a new inhibitor-resistant beta-lactamase with a pI of 7.6. SHV-56 is derived from SHV-11 by the single substitution K234R. This mutation therefore evidences a new critical site for inhibitor resistance among SHV enzymes.

BACKGROUND & OBJECTIVE Extended-spectrum beta-lactamases (ESBLs) are rapidly evolving group of beta-lactamase enzymes produced by the Gram negative bacteria. These enzymes have been derived from TEM and SHV genes by mutations and have been well described in Klebsiella pneumoniae. Information on molecular types of ESBL positive Klebsiella sp. is lacking from India. We therefore undertook this st...

SHV extended-spectrum beta-lactamases (ESBLs) arise through single amino acid substitutions in the parental enzyme, SHV-1. In order to evaluate the effect of genetic dissimilarities around the structural gene on MICs, we had previously devised an isogenic system of strains. Here, we present an extended version of the system that now allows assessment of all major types of SHV beta-lactamases as...

Klebsiella pneumoniae ML2011, a multiresistant isolate, was isolated from the Military Hospital of Tunis (Tunisia). The determination of the minimal inhibitory concentrations exhibited by K. pneumoniae ML2011 was performed by Etest. The crude extract of the isolates contains four different β -lactamases with pI 5.5, 7.3, 7.6, and 8.6. Only the β -lactamases with pI 7.3 and pI 8.6 were transferr...

The aim of this study was to investigate the presence and prevalence of bla(TEM), bla(SHV), and bla(CTX-M) and bla(GES)-like genes, responsible for extended spectrum beta-lactamases (ESBLs) production in clinical isolates of Klebsiella pneumoniae collected from a Brazilian tertiary care hospital. Sixty-five ESBL producing K. pneumoniae isolates, collected between 2005 and 2007, were screened by...