Screening and Identification of Metallo-beta-Lactamase Gene in Clinical Isolates of Imipenem-Resistant Pseudomonas Aeruginosa

Kim, In Suk; Oh, Won Il; Song, Jae Hoon; Lee, Nam Yong

Abstract

BACKGROUND
The therapeutic difficulty due to wide-spread emergence of multiply resistant strains is a major problem in Pseudomonas aeruginosa infection. Carbapenem-resistant P. aeruginosa strains are being isolated with increasing frequency. Clinical isolates of P. aeruginosa with transferable imipen-em resistance due to production of metallo-beta-lactamase (MBL) have been reported. This study was performed to determine the usefulness of the imipenem-EDTA disk test to detect MBL, to examine the prevalence of MBL in a tertiary care hospital in Korea. METHODS: One hundred sixteen P. aeruginosa isolates with reduced susceptibilities to imipenem were collected during the period of 2000-2003 in the Samsung Medical Center. Imipenem-resistant P. aeruginosa isolates were examined for MBL production by imipenem-EDTA disk tests. To detect of blaIMP-1 , blaVIM-1, and blaVIM-2 genes, polymerase chain reactions (PCR) were performed and the positive isolates were confirmed by sequencing. RESULTS: Among 116 clinical isolates of P. aeruginosa, 20 isolates (17.2%) were positive for the imipenem-EDTA disk tests. Nineteen isolates (16.4%) carried VIM-2. Accoroding to PCR results, the sensitivity, specificity, and test efficiency of the imipenem-EDTA disk tests were 89%, 97%, and 96%, respectively. CONCLUSIONS: The imipenem-EDTA disk test is sensitive and specific for detecting VIM producer. VIM-2 may be an important MBL in P. aeruginosa in tertiary care hospitals the Korea. The spread of MBL genes could compromise the future usefulness of carbapenem for the treatment of gram-neg-ative bacilli infections.