We investigated the molecular mechanisms and clonality of imipenem-non-susceptible Klebsiella pneumoniae isolates in a Taiwan national surveillance from 2002 to 2009. Genes for cabapenemases and plasmidic ampC-type and extended-spectrum beta-lactamases (EBSLs) were analysed by polymerase chain reaction. The major porin channels OmpK35 and OmpK36 were studied by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Molecular typing was performed with pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Our study revealed that all 29 isolates were ESBL producers. For K. pneumoniae in Taiwan from 2002 to 2009, most (84.6%, 11/13) imipenem-resistant (MIC > 2 mg/L) isolates carried bla(IMP-8). Isolates with an imipenem MIC of 2 mg/L produced ESBL with or without DHA-1 in combination with OmpK35/36 loss. PFGE analysis revealed that six small clusters of isolates were clonally related. The MLST grouping results were in concordance with the PFGE results. ST11, ST48 and ST101 were the predominant sequence types. Two novel ST types, ST1033 and ST1034, were found. The dominant clone in Taiwan, ST11, has been reported worldwide to be associated with various resistance mechanisms.
Date:
2013-01
Relation:
Journal of Medical Microbiology. 2013 Jan;63(Pt 1):101-107.
