Escherichia coli (328 isolates), Klebsiella pneumoniae (296), Klebsiella oxytoca (44), and Proteus mirabilis (33) isolates collected during 2012 from the nine U.S. census regions and displaying extended-spectrum-β-lactamase (ESBL) phenotypes were evaluated for the presence of β-lactamase genes, and antimicrobial susceptibility profiles were analyzed. The highest ESBL rates were noted for K. pne...

Background & objectives: Members of the family enterobacteriaceae comprise the most common gram-negative isolates in microbiology laboratories. Amongst these members, multiple antibiotic-resistant isolates including those producing extended spectrum β-lactamases (ESBL) and AmpC β-lactamases (AmpC) have increased steadily. Further, metallo-β-lactamase (MBL) producing strains are also recently de...

Klebsiella pneumoniae strains producing extended-spectrum β-lactamases (ESBL) exhibit resistance to antibiotic classes. The production of ESBLs (TEM-1, TEM-2, SHV-1, OXA-1) results in resistance to ampicillin, ticarcillin, piperacillin and cephalosporins. High levels of β-lactamases leads to development of resistance to β-lactamase inhibitors. The present study deals with characterizing antimic...

A prospective analysis on β-lactam resistance mechanisms and β-lactamase prevalence was conducted on Prevotella intermedia and Prevotella nigrescens recovered from patients with chronic periodontitis and peritonsillar abscesses. Both phenotypic and genotypic methods were performed to characterize the β-lactamases, their coding genes and their genetic contexts. Overall, β-lactamase production wa...

background: organisms producing ctx-m-β-lactamase are emerging around the world as a source of resistance to oxyiminocephalosporins such as cefotaxime. however, the laboratory detection of these strains is not well defined. the aim of this study was to determine the presence and prevalence of known ctx-m-β-lactamases genes in clinical isolates of  escherichia coli from hospitals of tehran. meth...

background and objectives: klebsiella pneumoniae is an opportunistic pathogen responsible for up to 10% of nosocomial infections. the emergence and spread of multidrug resistant k. pneumoniae , mostly due to the production of extended-spec- trum β-lactamases (esbl) and carbapenemases, is often responsible for antibiotic treatment failure of these infections. we compared the antibiotic resistanc...

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...