Korean J Clin Microbiol.  2005 Apr;8(1):26-33.

Prevalence of Imipenem-Resistant Pseudomonas aeruginosa Isolates and Mechanisms of Resistance

Affiliations
  • 1Department of Pediatrics, Kosin University College of Medicine, Busan, Korea.
  • 2Department of Laboratory Medicine, Kosin University College of Medicine, Busan, Korea.
  • 3Department of Quality Improvement, Kosin University Gospel Hospital, Busan, Korea.

Abstract

BACKGROUND
Spread of imipenem-resistant Pseudomonas aeruginosa isolates is an important clinical threat. The aim of this study is to survey the prevalence of carbapenem-resistant P.aeruginosa isolates in a university hospital, Busan, Korea, and to determine the mechanisms of the resistance.
METHODS
P.aeruginosa isolates from the patients in Kosin University Gospel Hospital were collected during the period of June through September, 2004. Antimicrobial susceptibilities were tested by the disk diffusion method, and production of carbapenemase and metallo-beta-lactamase was determined by the modified Hodge and EDTA-disk synergy tests, respectively. MICs were determined by the agar dilution method, and pIs of beta-lactamases were determined by the isoelectric focusing. Genotypes of carbapenemases were determined by direct sequencing of amplified products.
RESULTS
A total of 77 clinical isolates of P.aeruginosa were collected. Twenty-two (55.0%) and 15 (37.5%) isolates showed positive results in the modified Hodge and EDTA-disk synergy tests, re-spectively. Searches for bla OXA-23 and bla IMP-1 genes showed positive results in 15 and 12 isolates, respectively. MIC ranges of imipenem and meropenem to OXA-23-producing isolates were 8-16 microgram/mL and 2-32 microgram/mL, respectively, and those to IMP-1-producing isolates were 2-> or =256 microgram/mL and 2-128 microgram/mL, respectively.
CONCLUSION
Production of OXA-23 or IMP-1 is the most prevalent mechanism of imipenem-resistance in P.aeruginosa isolates in a university hospital, Busan, Korea. Periodical surveys are necessary to monitor the spreading of imipenem-resistant isolates and emerging new mechanisms of imipenem-resistance.

Keyword

Pseudomonas aeruginosa; IMP-1; OXA-23; Imipenem-resistance

MeSH Terms

Agar
beta-Lactamases
Busan
Diffusion
Genotype
Humans
Imipenem
Isoelectric Focusing
Korea
Prevalence*
Pseudomonas aeruginosa*
Pseudomonas*
Agar
Imipenem
beta-Lactamases
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