Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology


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pISSN 2288-0585 eISSN 2288-6850

Characterization of Class 1 Integrons in Metallo-βlactamase-producing Pseudomonas aeruginosa

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2009 March, Volume 12, Issue 1, pages 17-23.

Characterization of Class 1 Integrons in Metallo-βlactamase-producing Pseudomonas aeruginosa

Ji Youn Sung, Sun Hoe Koo, Kye Chul Kwon, Jong Woo Park, Chi Seon Ko, So Youn Shin, Jeong Hoon Song

Department of Laboratory Medicine, College of Medicine, Chungnam National University, Daejeon, Korea


Background: The genes of metallo-β-lactamase (MBL), a powerful carbapenemase, are carried as a part of the mobile gene cassettes inserted into integrons playing an important role in rapid dissemination of antibiotic resistance genes among bacterial isolates. In this study, we investigated carbapenemase genes and class 1 integrons integrated into the gene cassettes in imipenem-non susceptible P. aeruginosa.

Methods: From July 2006 to March 2008, 81 consecutive, non-duplicate, imipenem-non susceptible P. aeruginosa were isolated at Chungnam National University Hospital in Chungcheong province of Korea. The modified Hodge and double disk synergy tests were conducted for the screening of carbapenemase and MBL production, respectively, and PCR and DNA sequencing were performed for the detection of carbapenemase genes and class 1 integron gene cassettes. We also employed the repetitive element sequence-based (Rep)-PCR method for an epidemiologic study.

Results: MBLs were detected in 13.6% (11/81) of imipenem-non susceptible P. aeruginosa. Ten isolates were found to carry blaIMP-1, whereas 1 isolate was found to carry a blaVIM-2. All of the IMP-1-producing strains harbored 4.0 kb class 1 integron containing chloramphenicol, aminoglycoside, and β-lactam- resistant genes. However, blaIMP-1 was not detected at class 1 integron. A 2.5 kb class 1 integron harboring blaVIM-2 was detected in a VIIM-2- producing strain. One identical pattern was observed in ten IMP-1 producing strains.

Conclusion: IMP-1 producing P. aeruginosa strains are currently distributed throughout Chungcheong province of Korea. In particular, all of the strains harbored class 1 integrons containing variant antibiotic resistance gene cassettes. (Korean J Clin Microbiol 2009;12:17-23)


Metallo-β-lactamase (MBL), Class 1 integron, Multidrug resistance Pseudomonas aeruginosa