Molecular basis of AmpC hyperproduction in clinical isolates of Escherichia coli.

Prevalence and molecular characterization of clinical isolates of Escherichia coli expressing an AmpC phenotype.

OBJECTIVES To establish the prevalence of the AmpC beta-lactamase phenotype in clinical isolates of Escherichia coli and characterize the genetic resistance mechanisms causing the observed phenotype. METHODS Clinical E. coli (n = 74) with reduced susceptibility to third-generation cephalosporins and resistance to cefoxitin were collected from the Department of Clinical Microbiology at Hvidovr...

Characterization co-existence of ESBLs, AmpC and MBLs in Escherichia coli and Klebsiella pneumoniae isolates from Khorramabad Hospitals

Background: Prevalence of co-existence of extended-spectrum β-lactamases (ESBLs), metallo-beta-lactamase (MBLs) and AmpC-β-lactamases producing isolates in these bacteria is a serious problem in treatment of infections. The aim of this study was to characterization co-existence of ESBLs, AmpC and MBLs in Escherichia coli and Klebsiella pneumoniae isolates from Khorramabad hospitals. Materials ...

Phenotypic Identification and Antibiotic Susceptibility Pattern of AmpC beta-Lactamase Producing Escherichia coli and Klebsiella pneumoniae Isolated from Urinary Tract Infections from a Tertiary Care Hospital of Rawalpindi, Pakistan

Introduction: This study is aimed to compare phenotypic test methods and determine antibiotic susceptibility pattern of AmpC beta-lactamase producing uropathogenic Escherichia coli and Klebsiella pneumoniae in clinical isolates. Method: E. coli and K. pneumoniae were identified by standard microbiological procedures. Screening of AmpC beta-lactamase production was done by using cefoxitin disc (...

PCR Detection of Plasmid Mediated TEM, SHV and AmpC β-Lactamases in Community and Nosocomial Urinary Isolates of Escherichia coli

ampC beta-lactamase hyperproduction in Escherichia coli: natural ampicillin resistance generated by horizontal chromosomal DNA transfer from Shigella.

Six ampicillin-resistant clinical isolates of Escherichia coli that hyperproduced the chromosomal ampC beta-lactamase were studied. By DNA sequence analysis, we found that five of them were identical over an entire 449-base-pair sequence and carried a novel strong ampC promoter [Olsson, O., Bergström, S. & Normark, S. (1982) EMBO J. 1, 1411-1416]. Except for one base pair this sequence was iden...