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


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pISSN 2288-0585 eISSN 2288-6850

Characteristics of Acquired β-lactamase Gene in Clinical Isolates of Multidrug-resistant Pseudomonas aeruginosa

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2008 December Volume 11, Issue 2, pages 98-106.

Characteristics of Acquired β-lactamase Gene in Clinical Isolates of Multidrug-resistant Pseudomonas aeruginosa

Sun Yang Chung1, Ji Youn Sung2, Kye Chul Kwon2, Jong Woo Park2, Chi Seon Ko2, So Youn Shin2, Jeong Hoon Song2, Sun Hoe Koo2

1Health Promotion Center, Samsung Medical Center, Seoul, 2Department of Laboratory Medicine, Chungnam National University College of Medicine, Daejeon, Korea


Background: Recently, there have been reports of infections with multidrug-resistant Pseudomonas aeruginosa. To determine the mechanism of the resistance, we investigated the prevalence of Ambler class A and D β-lactamases, their extended-spectrum derivatives, and class B and D carbapenemase in multidrug-resistant P. aeruginosa isolates.

Methods: During the period of March 2006 to May 2007, clinical isolates of multidrug-resistant P. aeruginosa were collected from patients in Chungnam National University Hospital, Daejeon, Korea. Inhibitor-potentiated disk diffusion tests were used for the screening of metallo-β-lactamase (MBL) production. PCR and DNA sequencing were conducted for the detection of β-lactamase genes. We also employed the enterobacterial repetitive intergenic consensus (ERIC)- PCR method for an epidemiologic study.

Results: A total of 37 consecutive, non-duplicate, multidrug-resistant P. aeruginosa were isolated. Twenty- nine of 37 isolates harbored blaOXA-10 (56.8%), blaOXA-2 (18.9%), and blaOXA-1 (5.4%). Only one isolate produced IMP-1, and it also harbored blaOXA-1. None harbored Ambler class A β-lactamase or class D carbapenemase. The strains producing OXA type β-lactamases showed a significantly higher resistance to aminoglycoside compared to non-producers. The ERIC-PCR pattern of the 19 OXA-10 producing strains indicated that the isolates were closely related in terms of clonality.

Conclusion: OXA type β-lactamases are the most prevalent among the acquired β-lactamases produced by multidrug-resistant P. aeruginosa isolated at a university hospital in Chungcheong Province. Besides β-lactam antibiotics, the strains harboring OXA type β-lactamase showed a significantly higher resistance to aminoglycoside and qunolone. (Korean J Clin Microbiol 2008;11:98-106)


Multidrug resistance, Pseudomonas aeruginosa, OXA type β-lactamase, Metallo-β– lactamase (MBL)