Antibiotic Resistance Profile and Distribution of Oxacillinase Genes Among Clinical Isolates of Acinetobacter baumannii in Shiraz Teaching Hospitals, 2012 - 2013

BACKGROUND: The emergence of multidrug-resistant Acinetobacter baumannii complicates the therapy of the related infections. Hospital isolates of A. baumannii are usually multidrug-resistant. The problem is compounded by increasing resistance to broad-spectrum antibiotics including carbapenems. OBJECTIVES: The aim of this study was to determine antimicrobial susceptibility patterns and distribution of bla(OXA-type) carbapenemases genes among A. baumannii isolates from hospitalized patients in Shiraz, Southwest Iran. MATERIALS AND METHODS: Two hundred A. baumannii isolates were recovered from different clinical specimens in four Shiraz teaching hospitals. Isolates were detected as A. baumannii by Microgen kit and PCR with specific primers of bla(OXA-51-like) gene. Antimicrobial susceptibility testing was determined by disk diffusion method for all the isolates. Multiplex PCR assays were performed for detection of bla(OXA-23-like), bla(OXA-24-like) and bla(OXA-58-like) genes. RESULTS: All the isolates were susceptible to colistin and polymyxin B. Moreover, all of them were resistant to piperacillin, piperacillin-tazobactam, ampicillin, ceftazidime, cefoxitin and aztreonam. Eighty (40%) isolates had positive results for bla(OXA-23-like), 14 (7%) for bla(OXA-24-like) and 1 (0.5%) isolate for bla(OXA-58-like). The co-existence of studied genes was detected for bla(OXA-23-like) plus bla(OXA-24-like) in nine (4.5%) isolates. CONCLUSIONS: The prevalence of carbapenem resistant A. baumannii isolates in Shiraz hospitals is high. The bla(OXA-23-like) gene was the most frequent carbapenemase identified among resistant A. baumannii isolated in Shiraz hospitals. The increasing incidence of A. baumannii is a serious concern, therefore control of this pathogen and taking preventive measures are emphasized.