Prevalence and characteristics of ertapenem-nonsusceptible Escherichia coli in a Taiwanese university hospital, 1999 to 2007

Abstract

The present study was conducted to investigate the prevalence and characteristics of ertapenem-nonsusceptible (ETP-NS) Escherichia coli in a Taiwanese university. A total of 9,722 isolates collected in 1999, 2003, 2005, and 2007 were examined. Overall, 1.0% of all isolates from 66 patients were interpreted as ETP-NS on the basis of the disk diffusion test result. Most of these isolates were clonally unrelated and showed low-level ertapenem resistance, the production of CMY-2 cephalosporinase (86.4%), and decreased expression of the OmpF (97.0%) and/or OmpC (56.1%) porins. No carbapenemase was detected. The decreased porin expression was associated with disruptions of ompF or ompC in only about one-third of the ETP-NS isolates. During the study period, the prevalence of ETP-NS strains increased from 0.1 to 1.7%, accompanying an increase (0.8 to 17.6%) in the prevalence of CMY-2 producers. Coexistent or pre-existing clonally related ertapenem-susceptible (ETP-S) E. coli isolates were identified in 47.0% of all case patients, and almost all of the ETP-S isolates had the same β-lactamases as the ETP-NS isolates. Our study results suggest the restricted use of extended-spectrum cephalosporins to hinder the emergence and prevalence of carbapenem resistance in E. coli, which may arise by the accumulation of multiple resistance determinants.

Loss of Outer Membrane Protein C in Escherichia coli Contributes to Both Antibiotic Resistance and Escaping Antibody-Dependent Bactericidal Activity

“…Unlike OmpA, the variation in OmpC may be much higher than we thought. Our previous data showed a higher mutation rate of the ompC gene (truncated forms or insertion) in multidrug-resistant E. coli (23,41). We also found that the OmpC mutant can be detected from natural selection, and these mutants not only had similar carbapenems and cefepime resistance, but also had similar serum bactericidal activities ( Fig.…”

Carbapenem Therapy for Bacteremia Due to Extended-Spectrum-β-Lactamase-Producing Escherichia coli or Klebsiella pneumoniae: Implications of Ertapenem Susceptibility

“…It remains undefined if there is any difference in long-term outcome between different treatment groups. Finally, in Taiwan there are no indigenous isolates with KPC or NDM enzymes, and the mechanisms mediating carbapenem resistance in E. coli isolates were production of AmpC beta-lactamases in conjunction with porin deficiency (2,25). The correlation between clinical outcome and carbapenem susceptibility may not be generalized to Western countries with a variable prevalence of KPC or NDM beta-lactamases among Enterobacteriaceae isolates.…”

Heteroresistance to Cephalosporins and Penicillins in Acinetobacter baumannii

“…Cell debris was removed by centrifugation, and 2 l of supernatant was used as a source of template DNA in a 50-l PCR. Strains were analyzed for ␤-lactamase genes (bla CTX-M , bla OXA , bla SHV , and bla TEM ), using the primers described previously (27,28). The purified PCR products were directly sequenced using the automated ABI Prism 3730 DNA sequencer (Applied Biosystems, Foster City, CA).…”