Molecular Detection of blaOXA (-type) Carbapenemase Genes and Antimicrobial Resistance Patterns among Clinical Isolates of Acinetobacter baumannii

Acinetobacter baumannii is a bacterium found in most places, especially in clinics and hospitals, and an important agent of nosocomial infections. The presence of class D enzymes such as OXA-type carbapenemases in A. baumannii is proven to have a key function in resistance to carbapenem. The aim of the current study is to determine the blaOXA (-type) carbapenemase genes and antimicrobial resistance among clinically isolated samples of A. baumannii. We assessed 100 clinically isolated specimens of A. baumannii from patients in intensive care units of educational hospitals of Hamadan, West of Iran. The A. baumannii isolates' susceptibility to antibiotics was performed employing disk diffusion method. Multiplex polymerase chain reaction was used to identify the bla (OXA-24-like) , bla (OXA-23-like) , bla (OXA-58-like) , and bla (OXA-51-like) genes. The bla (OXA-23-like) , bla (OXA-24-like) (,) and bla (OXA-58-like) genes' prevalence were found to be 84, 58, and 3%, respectively. The highest coexistence of the genes was for bla (OXA-51/23) (84%) followed by bla (OXA-51/24-like) (58%). The bla (OXA-51/23-) (like) pattern of genes is a sort of dominant gene in resistance in A. baumannii from Hamadan hospitals. The highest resistance to piperacillin (83%) and ciprofloxacin (81%) has been observed in positive isolates of bla (OXA-23-like) . The A. baumannii isolates with bla (OXA-58-like) genes did not show much resistance to antibiotics. Based on the results of the phylogenetic tree analysis, all isolates have shown a high degree of similarity. This study showed the high frequency of OXA -type carbapenemase genes among A. baumannii isolates from Hamadan hospitals, Iran. Thus, applying an appropriate strategy to limit the spreading of these strains and also performing new treatment regimens are necessary.