| 16816399 |
Yan JJ, Hsueh PR, Lu JJ, Chang FY, Ko WC, Wu JJ: Characterization of acquired beta-lactamases and their genetic support in multidrug-resistant Pseudomonas aeruginosa isolates in Taiwan: the prevalence of unusual integrons. J Antimicrob Chemother. 2006 Sep;58(3):530-6. Epub 2006 Jul 1.
OBJECTIVES: The present study was conducted to investigate acquired beta-lactamases and their genetic support in 26 Pseudomonas aeruginosa isolates that were resistant to nearly all antipseudomonal drugs from six medical centres in Taiwan. METHODS: Acquired beta-lactamases and their genetic support were determined by PCR-based strategies. RESULTS: Four and 16 of the 26 isolates were found to produce VIM-2 and VIM-3 metallo-beta-lactamases (MBLs), respectively, and 1, 1 and 2 isolates produced OXA-17, OXA-10 and PSE-1, respectively. These bla genes are all in class 1 integrons that are probably chromosomally located. The bla (VIM-3)-containing integron, with a deletion between int1 and the bla (VIM-3) structural gene, has six gene cassettes, bla (VIM-3), a probable fosfomycin resistance determinant, aacA4, aacA4, aadB and aacA4. The bla (VIM-2)-containing integron, without detectable 5'-conserved segment, contains four genes cassettes (aacA7-bla (VIM-2)-dhfr-aacA5) and is ended by tniC. The bla (OXA-10)-containing integron includes a catB3 cassette and a fused gene cassette, which is made up of bla (OXA-17) and a novel streptomycin-spectinomycin gene, designated aadA15. The bla (OXA-17)-containing integron has three gene cassettes (aacA4-catB2-bla (OXA-17)) but the 59-base element of the bla (OXA-17) cassette is interrupted by a putative transposase gene. The bla (PSE-1)-containing integron has three gene cassettes, aacA4, an aadA3-related gene designated aadA3b and bla (PSE-1). PFGE revealed genetic diversity among the multidrug-resistant isolates from different hospitals. CONCLUSIONS: This study demonstrated the high prevalence of VIM-type MBLs and the presence of unusual bla-encoding integrons in multidrug-resistant P. aeruginosa isolates in Taiwan. The spread of bla (VIM-2)-related genes by horizontal transfer might have occurred. |
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