Molecular epidemiology of carbapenem-resistant Pseudomonas aeruginosa carrying metallo-β-lactamase genes in Taiwan

Seventy-two isolates of carbapenem-resistant Pseudomonas aeruginosa (CRPA) collected through the Taiwan Surveillance of Antimicrobial Resistance (TSAR) program in 2000 and 2002 were studied for carriage of metallo-β-lactamase (MBL), integrase genes, and integrons. Epidemiologic relatedness was determined using pulsed-field gel electrophoresis. The prevalence of the MBL genes among CRPA was 36.0% (9 of 25) in TSAR II and 17.0% (8/47) in TSAR III, with prevalence in surveyed hospitals being 19.1% (4/21, TSAR II) and 23.1% (6 of 26, TSAR III). The blaVIM-3 was detected in 15 of the 17 MBL-positive isolates; the remainder possessed blaVIM-2. The blaIMP was not evident. Class 1 integron was detected in all MBL-positive isolates; amplicon DNA sequences containing the blaVIM-3 regions were all identical. All MBL-positive isolates remained susceptible to colistin. Molecular typing revealed a predominant strain that comprised 14 of the isolates among the various surveyed hospitals.