title: Occurrence of extended-spectrum beta-lactamases among chromosomal AmpC-producing Enterobacter cloacae, Citrobacter freundii, and Serratia marcescens in Korea and investigation of screening criteria.
abstract: We assessed the occurrence and screening criterion for extended-spectrum beta-lactamases (ESBLs) among AmpC-producing Enterobacter cloacae, Citrobacter freundii, and Serratia marcescens. The 413 isolates (158 E. cloacae, 126 C. freundii, and 129 S. marcescens) isolated from 11 clinical laboratories in Korea were investigated. ESBL production was confirmed by double-disk synergy test and inhibitor-potentiated diffusion test using ceftazidime (CAZ), cefotaxime (CTX), aztreonam (AZT), and cefepime (FEP) with or without clavulanic acid. One hundred seven isolates (25.9%) were as ESBL producers. Of them, resistance was transferred by conjugation in 82 isolates. In transconjugants, structural genes for CTX-M (53.7%), TEM (46.3%), SHV (29.3%) were found. To evaluate the ESBL screening minimum inhibitory concentration (MIC) criteria, MICs for cefuroxime, CAZ, CTX, AZT, and FEP were determined and cutoff value was selected using receiver operator characteristic curve. The FEP MIC > or = 1 microg/mL had the highest sensitivity (95.3%), specificity (82.7%), and positive (65.8%) and negative predictive values (98.3%).
authors.affiliation: Department of Clinical Pathology, College of Medicine, The Catholic University of Korea, Kangnam St. Mary's Hospital, Seoul 137-040, Korea. yjpk@catholic.ac.kr
authors.forename: Yeon-Joon
authors.initials: YJ
authors.lastname: Park
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Park
authors.forename: Eun-Jee
authors.initials: EJ
authors.lastname: Oh
authors.forename: Jung-Jun
authors.initials: JJ
authors.lastname: Park
authors.forename: Kyo-Young
authors.initials: KY
authors.lastname: Lee
authors.forename: Gun-Jo
authors.initials: GJ
authors.lastname: Woo
authors.forename: Kyungwon
authors.initials: K
authors.lastname: Lee
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000096:biosynthesis*; D000077723:Cefepime; D002511:Cephalosporins / Q000494:pharmacology; D002876:Chromosomes, Bacterial; D016971:Citrobacter freundii / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D003227:Conjugation, Genetic; D016972:Enterobacter cloacae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D006801:Humans; D007723:Korea; D008826:Microbial Sensitivity Tests / Q000379:methods / Q000592:standards; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D012706:Serratia marcescens / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002511:Cephalosporins; D000077723:Cefepime; C048795:AmpC beta-lactamases; D001618:beta-Lactamases