Korean J Clin Microbiol.  2007 Oct;10(2):128-134.

Prevalence of Carbapenemase and Integrase Genes in Imipenem-resistant Acinetobacter baumannii and Pseudomonas aeruginosa Collected over Several Years in a University Hospital

• Oh HR
• Jang SJ
• Yu FN
• Park G
• Li XM
• Shin SH
• Kim WY
• Moon DS
• Park YJ

Abstract

BACKGROUND: The incidence of infections with imipenem- resistant Acinetobacter baumannii (IRAB) and Pseudomonas aeruginosa (IRPA) is increasing worldwide, and recent molecular studies indicate that the prevalence of carbapenemases is increasing in various parts of the world. However, few long-term longitudinal studies have assessed the prevalence of IRAB- and IRPA-derived carbapenemases and integrases in a hospital setting in Korea.
METHODS
The carbapenemase genes (blaOXA-23, blaOXA-24, blaOXA-58, blaIMP-1, blaVIM-2, blaSIM-1, blaSPM-1) and integrase genes (intI1, intI2, intI3) produced by 46 IRAB strains and 51 IRPA strains collected at Chosun University Hospital between 2003 and 2006 were determined by PCR.
RESULTS
The IRAB strains produced class 1 integrases more often than did the IRPA strains. However, the incidence increased steadily in both strains, reaching 100% in 2006. Carbapenemases of blaIMP-1 and blaVIM-2 types were found in 57% and 64% of the IRAB strains, respectively, in 2003. However, only one strain with blaVIM-2 was found in 2004 and another one with blaIMP-1 in 2005. The prevalence of carbapenemases was very low in the IRPA strains, just one strain with blaVIM-2 in 2005 and another one with blaoxa-23 in 2006. No other types of carbapenemase genes were detected in both strains. Rep-PCR of IRAB strains in 2003 showed different patterns.
CONCLUSION
The incidence of carbapenemase varied by year but was generally low, except in 2003. The prevalence of class 1 integrases was consistently high and increased every year. The reason for the high prevalence of carbapenemases in 2003 is still unknown, but we assumed that it was not from the spread of a clone containing either blaIMP-1 or blaVIM-2 because the strains exhibited different rep-PCR patterns.

Keyword

Imipenem; Pseudomonas aeruginosa; Acinetobacter baumannii; Carbapenemase; Integrase; Metallo-beta-lactamase

MeSH Terms

Acinetobacter baumannii*
Acinetobacter*
Clone Cells
Imipenem
Incidence
Integrases*
Korea
Polymerase Chain Reaction
Prevalence*
Pseudomonas aeruginosa*
Pseudomonas*
Imipenem
Integrases