Detection and characterization of class 1 integrons among carbapenem-resistant isolates of Acinetobacter spp. in Malaysia

Background and purpose: To detect and characterize class 1 integrons among carbapenem-resistant strains of Acinetobacter spp. at University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia. Methods: Thirty nine carbapen ern-resistant Acinetobacter strains were obtained from UMMC from August 2003 to March 2004 and analyzed for the presence of b/a(IMP) genes and class 1 integrons. Results: Class 1 integrons were detected in 31 of 39 strains. Two Acinetobacter calcoaceticus strains harbored an integron-borne b/a(IMP-4) metallo-beta-lactamase, 1 of which was located on a 36-kb plasmid. Two different amplified products were found in the 31 isolates with 3 restriction pattern profiles 1, 2, and 3. Correlation was observed between carriage of class 1 integrons and genomic relatedness among these isolates, indicating that particular mechanisms of carbapenem resistance could have been acquired by genotypically distinct clinical isolates of Acinetobacter spp. Conclusion: Although class 1 integrons are widely disseminated among clinical isolates of Acinetobacter spp. they do not play a major role in the spread of carbapenem resistance.