title: Evaluation of phenotypic screening methods for detecting plasmid-mediated AmpC beta-lactamases-producing isolates of Escherichia coli and Klebsiella pneumoniae.
abstract: Detection of plasmid-mediated (P-M) AmpC beta-lactamase-producing isolates is considered critical for epidemiologic studies and hospital infection control, but the documents of the Clinical and Laboratory Standards Institute do not contain any recommendation for the phenotypic detection. In this study, phenotypic detection methods, cefoxitin-Hodge test and induction test, were evaluated using cefoxitin-resistant Escherichia coli and Klebsiella pneumoniae isolates. The cefoxitin-Hodge test detected all bla(CMY-10), and 97.4% of bla(CMY-2) allele-positive isolates, but only 57.3% of bla(DHA-1) allele-positive isolates. Induction test with an aztreonam and an amoxicillin-clavulanic acid disk was more sensitive than with cefoxitin disk, which detected 86.6% of bla(DHA-1) allele-positive isolates. These phenotypic tests should be useful to screen P-M AmpC beta-lactamase-producing E. coli and K. pneumoniae isolates.
authors.affiliation: Department of Laboratory Medicine, Yonsei University Hospital, Seoul 120-752, South Korea.
authors.forename: Kyungwon
authors.initials: K
authors.lastname: Lee
authors.forename: Seong Geun
authors.initials: SG
authors.lastname: Hong
authors.forename: Yeon Joon
authors.initials: YJ
authors.lastname: Park
authors.forename: Hye Soo
authors.initials: HS
authors.lastname: Lee
authors.forename: Wonkeun
authors.initials: W
authors.lastname: Song
authors.forename: Joseph
authors.initials: J
authors.lastname: Jeong
authors.forename: Dongeun
authors.initials: D
authors.lastname: Yong
authors.forename: Yunsop
authors.initials: Y
authors.lastname: Chong
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000032:analysis* / Q000235:genetics; D002440:Cefoxitin / Q000494:pharmacology; D004790:Enzyme Induction; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D004927:Escherichia coli Infections / Q000382:microbiology; D006801:Humans; D007710:Klebsiella Infections / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D007723:Korea; D008826:Microbial Sensitivity Tests; D010957:Plasmids; D001618:beta-Lactamases / Q000032:analysis* / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002440:Cefoxitin; C103022:beta-lactamase CMY-2; C048795:AmpC beta-lactamases; C491822:CMY-10 beta-lactamase; D001618:beta-Lactamases