Investigation of Beta-lactamases in Carbapenem-resistant A. baumannii Isolates

Objectives: To investigate the prevalence of PER-1, PER-2, GES, IMP-1, VIM-2, OXA-23, and OXA-24 type beta-lactamases in carbapenem-resistant Acinetobacter baumannii isolates, in view of the fact that Beta-lactamase production is the most important mechanism of acquired beta-lactam resistance in Gram-negative pathogens. Design: Experimental study Setting: Department of Medical Microbiology, School of Medicine, Pamukkale University, Denizli, Turkey Subjects: From January 2009 to December 2009, a total of 98 carbapenem-resistant A. baumannii bacteria were isolated from patients. Intervention: In-house PCR was performed for the detection of PER-1, PER-2, GES, IMP-1, VIM-2, OXA-23, and OXA-24 beta-lactamase genes in those clinical carbapenem-resistant A. baumannii isolates. Main Outcome Measure: Prevalence rate of beta-lactamase genes in carbapenem-resistant A. baumannii isolates Results: GES beta-lactamase was found in 59 isolates (60.20%). PER-1 was found in eight isolates (8.16%). IMP-1 was found in five isolates (5.10%). OXA-24 was detected in two isolates (2.04%). No isolate possessed VIM-2, PER-2, or OXA-23 beta-lactamase genes. Conclusion: This study indicates that the GES type beta-lactamases are the most prevalent among carbapenem-resistant A. baumannii isolates in our hospital. Screening for beta-lactamases and strict infection control for these isolates will help prevent further spread of resistance.