Detection of OXA-Type Carbapenemase Genes in Acinetobacter baumannii Isolates from Nosocomial Infections in Isfahan Hospitals, Iran

Acinetobacter baumannii as one of the causes of nosocomial infections has become resistant to almost all antimicrobial agents. The emergence of resistance to carbapenems, one of the last drugs on the shelf, is the major concern about A. baumannii antimicrobial resistance. Resistance to carbapenems is mediated by production of class B and D carbapenemases. The aim of this study was to detect the resistance genes including blaOXA-23, 24, 51, and 58 in A. baumannii isolates from nosocomial infections in Isfahan hospitals. A total number of 456 clinical specimens were collected from nosocomial infections and evaluated in order to isolate A. baumannii strains. After identification of the isolates, the antibiotic sensitivity to carbapenems was assessed using disk diffusion method. The resistance genes of bla OXA-23, 24, 51, and 58 were detected by multiplex PCR method. Fifty A. baumannii isolates were isolated from clinical specimens. Fifty two percent of the isolates showed phenotypic resistance to the carbapenems (imipenem and meropenem). According to PCR results, 88% of resistant isolates had ≥1 blaOXA gene. The frequency of resistant isolates bearing blaOXA-23, blaOXA-24 and blaOXA-58 were 77%, 38% and 15% respectively. This study showed the high frequency of carbapenem resistance genes among A. baumannii isolates. Therefore, adopting an appropriate strategy to confine the spreading of these strains and also implementing new treatment regimens are necessary.