Molecular typing and resistance mechanisms of imipenem-non-susceptible Klebsiella pneumoniae in Taiwan: results from the Taiwan surveillance of antibiotic resistance (TSAR) study, 2002–2009

Abstract

We investigated the molecular mechanisms and clonality of imipenem-non-susceptible Klebsiella pneumoniae isolates collected during a Taiwan national surveillance programme, between 2002 and 2009. Genes for carbapenemases, plasmid-borne ampC-type genes and extended-spectrum b-lactamase (ESBL) genes were analysed by PCR. The major porin channels OmpK35 and OmpK36 were studied by SDS-PAGE. Molecular typing was performed with pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Our study revealed that all 29 of the isolates tested were ESBL producers. Of the K. pneumoniae isolates collected in Taiwan from 2002 to 2009, most (84.6 %, 11/13) imipenem-resistant (MIC .2 mg l "1 ) isolates carried the bla IMP-8 gene. Isolates with an imipenem MIC of 2 mg l "1 produced ESBLs 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. The predominant sequence types (ST) were ST11, ST48 and ST101. Two novel STs, ST1033 and ST1034, were found. The dominant clone in Taiwan, ST11, has been reported worldwide to be associated with various resistance mechanisms.

Effect in virulence of switching conserved homologous capsular polysaccharide genes fromKlebsiella pneumoniaeserotype K1 into K20

“…2,17,18 Specific capsular serotypes have been documented with a high frequency to show hyper-virulence in mouse and human infections. 19 A cluster of genes are involved in capsule synthesis and driven by 2 promotors.…”

“…2,10,11 Construction of in-frame deletion mutants in Serotype K20 and CPS gene exchange from serotype K1 to K20…”

“…1 Recently, a new invasive syndrome has been defined in community-acquired liver abscesses with or without complications such as meningitis or endophthalmitis. 2 This invasive syndrome has been mostly attributed to K. pneumoniae with the capsular serotypes K1 or K2. Bacterial cell surface polysaccharides, including both capsular-(K antigen) and lipo-polysaccharides, have been well documented as important virulent factors in the establishment of infection.…”

First Report of bla IMP-8 in Raoultella planticola

“…1A). Detection of carbapenemases (bla KPC , bla NDM , bla VIM , bla IMP , bla NMC , bla SME , bla SPM-1 , bla GIM-1 , bla SIM-1 , bla IMI , bla GES , and bla OXA-48 ) and extendedspectrum ␤-lactamases (ESBLs) and AmpC genes (bla SHV , bla TEM , bla DHA , bla CMY , bla CTX-M-G1 , bla CTX-M-G2 , and bla CTX-M-G9 ) was performed, and only bla IMP-8 was found in these two isolates (8,9). Both isolates contained two plasmids (ca.…”

Novel 16S rRNA Methyltransferase RmtH Produced by Klebsiella pneumoniae Associated with War-Related Trauma

“…The strain was phenotypically confirmed as an ESBL producer, and screening of ␤-lactamase genes with PCR and sequencing showed that it carried bla CTX-M-15 as well as bla SHV-1 and bla OXA-1 . Multilocus sequence typing (www.pasteur.fr/mlst) (5) assigned the strain to sequence type (ST) 48, an ST which has been reported in association with ESBL production worldwide (6)(7)(8)(9)(10). Given the resistance phenotype consistent with 16S RMTase production, the strain was screened for 16S RMTase genes using PCR (2,11,12).…”