[Analysis of the metallo-beta-lactamase gene in multidrug-resistant Pseudomonas aeruginosa isolated at Showa University Hospital].

ABSTRACT

We conducted a molecular epidemiological analysis of multidrug-resistant Pseudomonas aeruginosa (MDRP) isolated at Showa University Hospital. The ratio of MDRP to total P. aeruginosa was 0.8% (1/132 strains) from September to December 1993. This ratio was increased to 1.8% (18/1000 strains) from October 2003 to October 2004. We analyzed the genome type and drug-resistant gene of 18 MDRPs isolated from October 2003 to October 2004, and 6 MDRPs isolated from January to April 2005 in a follow-up survey. Genome-type analysis using pulsed-field gel electrophoresis after SpeI restriction enzyme digestion revealed that 12 of the 24 MDRP strains had an identical genome type, indicating a possible nosocomial infection. In order to analyze the drug resistance mechanism, the 2-mercaptopropionic acid inhibition test was performed. Twenty of 24 MDRP strains were positive for metallo-beta-lactamase. Of all the metallo-beta-lactamase-positive strains, IMP type beta-lactamase was detected by PCR. Sequence analysis of the PCR product of IMP type betalactamase identified that 2 strains were IMP-1 and 18 were IMP-10. Of the 12 strains having an identical genome type, IMP-1 was detected in 1 strain and IMP-10 was detected in 11 strains. From our results, we conclude that P. aeruginosa with the same genome type was continuously colonized in the hospital and independently acquired a drug-resistant gene.