Emergence and dissemination of blaOXA-23-carrying imipenem-resistant Acinetobacter sp in a regional hospital in Taiwan

Abstract

Background: The distribution and characterization of OXA-type carbapenemases in Acinetobacter sp in Taiwan has less been reported. The aim of the study was to investigate the molecular epidemiology and OXA-type carbapenemase genes in a regional hospital in Taiwan.

Methods: Imipenem-resistant Acinetobacter sp were collected between 2005 and 2007 in a regional hospital. Genotyping was performed by pulsed-field gel electrophoresis. OXA-type carbapenemase genes were determined by multiplex polymerase chain reaction (PCR) and gene sequencing.

Results: A total of 136 isolates were collected. Fifty-six pulsotypes were identified. None of the pulsotypes established predominance throughout the 3-year period. Multiplex PCR of blaOXA genes showed that 99% (135/136) of the Acinetobacter sp possessed blaOXA51-like genes. The coexistences of blaOXA51-like/blaOXA-23-like and blaOXA51-like/blaOXA-24-like were detected in 19% (26/136) and 1% (2/136) of the isolates, respectively. Among blaOXA-23-like gene-carrying isolates, two isolates (Pulsotypes 18 and 20) were found in 2006 and the remainder (n=24), including Pulsotypes 27 (n=18), 29 (n=1), 52 (n=3), and 53 (n=2), were found in 2007. Sequencing performed on the 26 representative isolates confirmed the presence of the blaOXA-23 carbapenemase gene. Analysis of the genetic content of blaOXA-23 showed that these genes were presumably chromosomal and associated with the upstream-located insertion sequence ISAba1.

Conclusions: The emergence and imminent widespread of blaOXA-23-carrying imipenem-resistant Acinetobacter sp appeared in Taiwan during the period from 2006 to 2007.