Clonal spread of both oxyimino-cephalosporin- and cefoxitin-resistant Klebsiella pneumoniae isolates co-producing SHV-2a and DHA-1 beta-lactamase at a burns intensive care unit.
Over a 1-month period, a total of 16 ceftriaxone- and cefoxitin-resistant Klebsiella pneumoniae isolates were isolated from 15 patients hospitalised at a burns intensive care unit (ICU). These isolates showed negative results for extended-spectrum beta-lactamase (ESBL) by the Vitek system and were highly resistant to ceftazidime, aztreonam and cefoxitin (minimum inhibitory concentrations > or =128 microg/mL). The bla(SHV-2a) and bla(DHA-1) genes were detected by polymerase chain reaction and sequence analysis. Pulsed-field gel electrophoresis profiles of the isolates were identical. AmpC disk tests for AmpC enzymes as well as double-disk tests and Clinical and Laboratory Standards Institute (CLSI) confirmatory disk tests for ESBLs yielded positive results for all the isolates. However, only three isolates (18.8%) were shown to produce ESBL by CLSI confirmatory tests using broth microdilution. We report the first outbreak of colonisations and infections due to K. pneumoniae isolates co-producing an SHV-2a ESBL and a DHA-1 AmpC beta-lactamase in a Korean hospital, which were suggested to represent a single clonal spread at a burns ICU. In addition, this report presents problems associated with ESBL detection using broth microdilution in isolates that co-produce an ESBL and an AmpC beta-lactamase.
Song
Wonkeun
W
Department of Laboratory Medicine, Hallym University College of Medicine, Kangnam Sacred Heart Hospital, 948-1 Daelim-dong, Youngdeungpo-gu, Seoul 150-950, South Korea. swonkeun@hallym.or.kr
Lee
Kyu Man
KM
Kim
Han-Sung
HS
Kim
Jae-Seok
JS
Kim
Jonghyun
J
Jeong
Seok Hoon
SH
Roh
Kyoung Ho
KH
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002053:Burn Units; D002440:Cefoxitin / Q000494:pharmacology; D018550:Cephalosporin Resistance; D002511:Cephalosporins / Q000494:pharmacology; D004196:Disease Outbreaks; D006801:Humans; D007710:Klebsiella Infections / Q000453:epidemiology* / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D007723:Korea / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D002440:Cefoxitin; C490029:beta-lactamase SHV-2a; D001618:beta-Lactamases