background :    unfortunately, antibiotic resistance has become an increasingly critical problem in many countries like iran. since there are very few published data on antibiotics resistance in alborz province, the aim of this study was to survey the pattern of antimicrobial resistance and prevalence detection of tem-type beta-lactamases among clinical isolates of escherichia coli using univer...

Bacterial beta-lactamases are the major causes of resistance to beta-lactam antibiotics. Three classes of these enzymes are believed to have evolved from ancestral penicillin-binding proteins (PBPs), enzymes responsible for bacterial cell wall biosynthesis. Both beta-lactamases and PBPs are able to efficiently form acyl-enzyme species with beta-lactam antibiotics. In contrast to beta-lactamases...

OBJECTIVES To determine if the TEM beta-lactamases of Haemophilus influenzae are TEM-1 or derivatives thereof and associated exclusively with the overlapping Pa/Pb promoters. METHODS Single nucleotide specific PCR was used to discriminate the polymorphic nucleotides at positions 32 and 317 of the bla(TEM) genes of a collection of TEM-positive strains. RESULTS All bla(TEM) genes were found t...

β-lactamases production represents a determining factor in bacterial resistance to β-lactam antimicrobial agents. Over 200 enzymes have been characterized for their nucleotidic sequences and/or biochemical properties [1]. Among class A β-lactamases [2] TEM-1 is the commonest enzyme in Enterobacteriaceae. Because of wide spread use of antibiotics there has been the emergence of different variant...

The first outbreak of carbapenem-resistant Klebsiella pneumoniae isolates producing the plasmid-encoded carbapenem-hydrolyzing oxacillinase OXA-48 is reported. The 39 isolates belonged to two different clones and were collected at the University Hospital of Istanbul, Turkey, from May 2006 to February 2007, and they coproduced various beta-lactamases (SHV-12, OXA-9, and TEM-1 for clone A and CTX...

Escherichia coli is one of the leading causes of nosocomial infections. The most frequent mechanism of resistance to penicillins is the production of the common plasmidmediated TEM-1 -lactamase. Extended-spectrum lactamases of the TEM and SHV families, conferring resistance to newer -lactams such as oxyimino-cephalosporins, have also spread among E. coli clinical isolates. These enzymes are una...

knowledge of antimicrobial resistance patterns in e. coli, the predominant pathogen associated with urinary tract infections (uti) is important as a guide in selecting empirical antimicrobial therapy. methods: to describe the antimicrobial susceptibility of e. coli associated with uti in a major university hospital in tehran (iran), seventy-six clinical isolates of e. coli were studied for susc...

Extended spectrum beta-lactamases (ESBLs) confer bacterial resistance to third-generation cephalosporins, such as cefotaxime and ceftazidime, increasing hospital mortality rates. Whereas these antibiotics are almost impervious to classic beta-lactamases, such as TEM-1, ESBLs have one to four orders greater activity against them. The origins of this activity have been widely studied for the TEM ...

The first betalactamases were identified in a species of E.coli in 1940 (1). However, the ability of bacteria to produce enzymes that destroy the b-lactam ring was noted even before penicillin was developed. In fact, many of the gram-negative bacteria possess chromosomally mediated blactamases, which help the bacteria find a niche when faced with competition from other bacteria that naturally p...