Molecular Characterization of Multidrug Resistant Strains of Acinetobacter baumannii Isolated from Intensive Care Units in West of Iran

Abstract

According to the results of various studies using phenotypic methods, the prevalence of Multidrug Resistant (MDR) Acinetobacter baumannii (A. baumannii) isolates has been increasing worldwide. Pulsed-Field Gel Electrophoresis (PFGE) technique is known as the gold standard method to determine clonal characterization of bacterial species, especially A. baumannii. To determine the clonal relatedness and investigate the prevalence of integron classes 1 and 2 and genes encoding OXA-23 and 24 in A.baumanii isolates. A cross-sectional study was conducted from November 2011 to January 2013. A total of 140 A.baumannii isolates collected from three hospitals of Kermanshah were considered out of which 75 ICU isolates were included in this study. Antibiotics susceptibility test was done by disk diffusion method. Polymerase Chain Reaction (PCR) was performed in order to detect class 1 and 2 integrons and blaOXA-23-like, blaOXA-24-like genes. Isolates identified as MDR from a total of 75 Intensive Care Units (ICU) strains were subjected to genotyping for clonal relatedness. A total of 37 isolates among 75 ICU isolates were identified as MDR. The maximum drug resistance was observed against ceftriaxone, mezlocycline, cefotaxime, piperacilin, ciprofloxacin and imipenem. Frequency of Class 1 and Class 2 Integrons, blaOXA-23-like and blaOXA-24-like genes were 33(44%), 27(36%), 60(80%) and 14(18.6%) respectively. Four clusters with high level of similarity were obtained showing homogeneity among MDR isolates. Significant correlation between presence of integrons and resistance to different classes of antibiotic was observed in this study. Monitoring of drug resistance using gene integrase PCR and blaOXA gene by cluster analysis is very important to plan specific infection control measures due to MDR A. baumannii.