The Spread of Insertion Sequences Element and Transposons in Carbapenem Resistant Acinetobacter baumannii in a Hospital Setting in Southwestern Iran

BACKGROUND: Acinetobacter baumannii is one of the most important hospital pathogenic bacteria that cause infectious diseases. The present study aimed to determine the frequency of carbapenem resistance genes in association with transposable elements and molecular typing of carbapenem-resistant A. baumannii bacteria collected from patients in Shiraz, Iran. MATERIALS AND METHODS: A total of 170 carbapenem-resistant A. baumannii isolates were obtained from different clinical specimens in two hospitals. The minimum inhibitory concentrations (MIC) of imipenem were determined and the prevalence of OXA Carbapenemases, Metallo-β-lactamases genes, insertion sequences (IS) elements, and transposons were evaluated by the polymerase chain reaction (PCR) method. Finally, molecular typing of the isolates was performed by the Enterobacterial Repetitive Intergenic Consensus-PCR method. RESULTS: The MICs ranged from 16 to 1,024 µg/mL for imipenem-resistant A. baumannii isolates. Out of the 170 carbapenem resistant A. baumannii isolates, bla(OXA-24-like) (94, 55.3%) followed by bla(OXA-23-like) (71, 41.7%) were predominant. In addition, A. baumannii isolates carried bla(VIM) (71, 41.7%), bla(GES) (32, 18.8%), bla(SPM) (4, 2.3%), and bla(KPC) (1, 0.6%). Moreover, ISAba1 (94.2%) and Tn2009 (39.2%) were the most frequent transposable elements. Furthermore, (71, 44.0%) and (161, 94.7%) of the ISAba1 of the isolates were associated with bla(OXA-23) and bla(OXA-51) genes, respectively. Besides (3, 1.7%), (1, 0.6%) and (5, 2.9%) of bla(OXA-23) were associated with IS18, ISAba4, and ISAba2, respectively. Considering an 80.0% cut off, clusters and four singletons were detected. CONCLUSION: According to the results, transposable elements played an important role in the development of resistance genes and resistance to carbapenems. The results also indicated carbapenem-resistant A. baumannii bacteria as a public health concern.