전국 13개 기관에서 분리된 염색체성 AmpC β-lactamase 생성 Enterobacter Cloacae, citrobacter freundii 및 Serratia marcescens의 항균제감수성 양상

Abstract

Background :Antimicrobial resista1ce to third-generation cephalosporins in gram-negative bacteria, especially Enterobaeter, Citrobaeter, and Serratia spp., is increasing. The resistance mechanism of these organisms are hyperproduction of AmpC β-lactamase and plasmid-mediated extended-spectrum β-lactamase (ESBL). This study was to determine the ocgurrence of AmpC hyperproduction and ESBLs in E. cloacae, C. freundii, and S. marcescens over a3-month period in 2002.

Methods :We tested total of 619 consecutive, nonduplicate isolates (229 E. cloacae, 183 C. freundii, 207 S. marcescens) from 12 university hospitals and a commercial laboratory in Korea. Antimicrobial susceptibilities were tested using the disk diffusion method. AmpC hyperproduction was defined as nonsusceptible to cefotaxime or ceftazidime for E. cloacae and C. freundii and as nonsusceptible to cefotaxime for S. marcescens. ESBL production was determined by the double disk synergy test.

Results :Among the E. cloacae, C. freundii and S. marcescens derepressed strains were 20.5%, 30.1 %, and 31.4% and ESBL producers were 23.6%, 10.9%, and 15.5%, respectively. The AmpC derepressed strains and ESBL producers revealed lower susceptibility rates for ciprofloxacin, piperacillin, piperacillin-tazobactam and aminoglycosides

Conclusions :These data reveal that the occurrence of AmpC derepressants and ESBL producers among E. cloacae, C. freundii and S. marceseens is relatively high. Continued nationwide surveillance is necessary to provide information on the spread of these important mechanisms of resistance to β-lactams.