This study was performed to assess the prevalence and genotypes of plasmid-borne extended-spectrum beta-lactamases (ESBLs) and AmpC beta-lactamases in Escherichia coli in Korea. A total of 576 isolates of E. coli was collected from 12 Korean hospitals during May and July 2007. A phenotypic confirmatory test detected ESBLs in 82 (14.2 %) of the 576 E. coli isolates. The most common types of ESBL...

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...

We document the first report of plasmid-encoded CMY-2-type AmpC beta-lactamase identified among Shigella sonnei isolates resistant to ceftriaxone and obtained after an outbreak of bacillary dysentery in Taiwan. One hundred eighty-two children in two elementary schools in Yu-Li, Taiwan, where an outbreak occurred after a typhoon hit this area in 2001, were enrolled in this study. Clinical and ep...

Six Escherichia coli and 12 Klebsiella pneumoniae isolates from a single hospital expressed a common beta-lactamase with a pI of approximately 9.0 and were resistant to cefoxitin and cefotetan (MIC ranges, 64 to > 128 and 16 to > 128 micrograms/ml, respectively). Seventeen of the 18 strains produced multiple beta-lactamases. Most significantly, three K. pneumoniae strains were also resistant to...

OBJECTIVES To characterize the AmpC-type beta-lactamases produced by Escherichia coli clinical isolates. METHODS E. coli isolates recovered in a French hospital in 2006 were selected on the basis of a resistance phenotype consistent with increased AmpC production. The presence of genes coding for plasmid-mediated cephalosporinases as well as the existence of mutations in the chromosome-borne ...

Many clinical laboratories have problems detecting extended-spectrum beta-lactamases (ESBLs) and plasmid-mediated AmpC beta-lactamases. Confusion exists about the importance of these resistance mechanisms, optimal test methods, and appropriate reporting conventions. Failure to detect these enzymes has contributed to their uncontrolled spread and sometimes to therapeutic failures. Although Natio...

Starting from a clinical isolate of Serratia marcescens that produced a chromosomally encoded AmpC beta-lactamase inducibly, we isolated by stepwise selection two laboratory mutants that showed high levels of resistance to some cephalosporins. The 98R mutant apparently overproduced the unaltered beta-lactamase constitutively, but the 520R mutant produced an altered enzyme, also constitutively. ...

DHA-1, a plasmid-mediated cephalosporinase from a single clinical Salmonella enteritidis isolate, conferred resistance to oxyimino-cephalosporins (cefotaxime and ceftazidime) and cephamycins (cefoxitin and moxalactam), and this resistance was transferable to Escherichia coli HB101. An antagonism was observed between cefoxitin and aztreonam by the diffusion method. Transformation of the transcon...

Resistance to broad spectrum β lactams, mediated by extended spectrum beta lactamase (ESβL) and AmpC βL enzymes is fast spreading in Nigerian hospitals. Production of these enzymes has resulted in treatment failure especially if one of the second or third generation cephalosporins is used. A study was undertaken to determine the prevalence of each enzyme and coproduction of the two enzymes amon...

Environmental microorganisms represent the most relevant reservoir of resistance to antibiotics in the community, and this is due in part to the undue exposure of these organisms to antimicrobial agents. AmpC β-lactamases are clinically important cephalosporinases encoded on the chromosomes of bacteria in the Enterobacteriaceae family and some non-enteric bacteria including Pseudomonas aerugino...