bla(VIM-2) cassette-containing novel integrons in metallo-beta-lactamase-producing Pseudomonas aeruginosa and Pseudomonas putida isolates disseminated in a Korean hospital.
We investigated the phenotypic and genetic properties of metallo-beta-lactamase-producing Pseudomonas isolates collected at a tertiary-care hospital in Korea since 1995. The prevalence of imipenem resistance among Pseudomonas aeruginosa isolates reached 16% in 1997, when 9% of the resistant organisms were found to produce VIM-2 beta-lactamase, a class B enzyme previously found only in P. aeruginosa isolates from Europe. VIM-2-producing isolates of Pseudomonas putida were also detected. Resistance was transferable from both these species to P. aeruginosa PAO4089Rp by filter mating, although the resistance determinant could not be found on any detectable plasmid. Serotyping showed that many of the VIM-2-producing P. aeruginosa isolates belonged to serotypes O:11 and O:12, and pulsed-field gel electrophoresis of XbaI-digested genomic DNA revealed that many had identical profiles, whereas the P. putida isolates were diverse. Sequencing showed that the bla(VIM-2) genes resided as cassettes in class 1 integrons. In contrast to previous VIM-encoding integrons, the integron sequenced from a P. aeruginosa isolate had bla(VIM) located downstream of a variant of aacA4. bla(VIM) also lay in a class 1 integron in a representative P. putida strain, but the organization of this integron was different from that sequenced from the P. aeruginosa strain. In conclusion, the metallo-beta-lactamase produced by these imipenem-resistant Pseudomonas isolates was VIM-2, and the accumulation of producers reflected clonal dissemination as well as horizontal spread. Strict measures are required in order to control a further spread of resistance.
Lee
Kyungwon
K
Department of Clinical Pathology and Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Korea.
Lim
Jong Back
JB
Yum
Jong Hwa
JH
Yong
Dongeun
D
Chong
Yunsop
Y
Kim
June Myung
JM
Livermore
David M
DM
D003227:Conjugation, Genetic / Q000235:genetics; D004352:Drug Resistance, Microbial; D015378:Imipenem / Q000494:pharmacology; D016023:Integrins / Q000235:genetics*; D007525:Isoelectric Focusing; D007723:Korea; D008826:Microbial Sensitivity Tests; D009693:Nucleic Acid Hybridization; D010641:Phenotype; D010957:Plasmids / Q000235:genetics; D011552:Pseudomonas Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D016958:Pseudomonas putida / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012703:Serotyping; D001618:beta-Lactamases / Q000235:genetics*
D016023:Integrins; D015378:Imipenem; C425108:beta-lactamase bla(vim-2); D001618:beta-Lactamases