DOI: 10.1128/AAC.48.2.626-628.2004
ABSTRACT
Four blaVIM-2 gene-harboring Pseudomonas aeruginosa strains were identified. These strains possessed a class 1 integron harboring ORF1, blaVIM-2, and aacA4 gene cassettes. The transposon-mediated horizontal spread of the blaVIM-2 gene among these strains was suggested, which increases the threat that the blaVIM-2 gene will disseminate among diverse genera of bacteria.
The emergence of metallo-β-lactamase (MBL)-producing bacilli that are resistant to carbapenems is becoming a severe therapeutic problem (9). Two types of MBLs, IMP and VIM, have been reported (13). IMP-1 was identified in Pseudomonas aeruginosa in Japan in 1991 (15). Strains producing IMP-type MBLs have also been reported in Hong Kong (3), Taiwan (17), and Italy (12). Strains producing VIM-type MBLs were originally reported in European countries. VIM-1 was identified in P. aeruginosa in Italy in 1999 (7), and VIM-2 was identified in France (10). Thereafter, VIM-3 was identified in Taiwan (16). However, there have been few reports describing VIM-type-MBL-producing bacteria in Japan. The genes of both IMP- and VIM-type MBLs (blaIMP and blaVIM, respectively) are often encoded on mobile gene cassettes inserted into class 1 integrons (1, 7, 10). The class 1 integrons are genetic elements capable of integrating gene cassettes by a site-specific recombination mechanism (4). Gene cassettes are mobile units composed of a gene, most often an antibiotic resistance gene, and a recombination site, the 59-base element (4). Integrons are sometimes found as a part of transposons (4), which is probably the reason that they are found in many different genetic locations. In this work, we report on the characterization of the blaVIM-2 gene cassette-harboring class 1 integron identified in the P. aeruginosa clinical strains isolated in one hospital in Akita Prefecture, Japan.
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