Qom University of Medical Sciences Journal

Background and Objectives: Acinetobacter baumannii is an opportunistic bacterium and a cause of infection in human. This bacterium has complicated the treatment process by becoming resistant to many antibiotics. One of the most important characteristics of this organism is resistance to carbapenems. There has been several reports regarding isolation of carbapenem resistance in A. baumannii in Iran. The aim of this study was to evaluate antibiotic resistance pattern and presence of oxacillinase in Acinetobacter baumannii isolated from clinical specimens.

Methods: In this case cross-sectional study, a total of 140 isolates of Acinetobacter baumannii were collected from clinical specimens in Tehran Imam Khomeini Hospital and Shiraz Namazi Hospital, 2013-2014. The strains were identified using standard culturing, biochemical, and molecular methods. Antibiotic susceptibility test was performed by disk diffusion method against 12 different antibiotics, Then, multiplex PCR assay was used to detect the presence of 4 carbapenemase genes (blaOXA-23, 24, 51, 58).

Results: Among the strains, a resistance above 80% was seen to imipenem, gentamicin, amikacin, co-trimoxazole, cefepime, ceftazidime, tetracycline, and rifampicin antibiotics. Also, the samples isolated from clinical specimens in Namazi Hospital of Shiraz city, showed higher resistance to tigecycline, ampicillin, sulbactam, and ciprofloxacin. The multiplex PCR technique showed that the presence of blaOXA-23, blaOXA-24, and blaOXA-58 genes were, respectively, 82.1%, 4.3%, and 0.7%. All 14 strains identified phenotypically, carried blaOXA-51 gene.

Conclusion: According to the findings of this study, a resistance above 80% to the majority of antibiotics seen in our clinical isolates, emphasizes the necessity of using new drugs, such as tigecycline. Also, high presence (82.1%) of blaOXA-23 among the carbapenem resistant isolates of Acinetobacter baumannii emphasizes the importance of this gene in the induction of resistance.