The Prevalence of ESBL Isolates of Acinetobacter baumannii Using Pulsed-Field Gel Electrophoresis

Background: Antibiotics such as fluoroquinolones are used for treating infections caused by Gram-negative bacteria, including Acinetobacter baumannii strains some time have extended-spectrum B-lactamase (ESBL), but ESBL production is rather rare. Resistance to fluoroquinolones antibiotics is mediated by lactamases and other mechanisms of resistance. The aim of the present study was to investigate of the prevalence of ESBL production and clonal relatedness of A. baumannii in Iran. Materials and Methods: A. baumannii isolates identified from patients at hospitals in Kermanshah, Iran, were studied. The double disk method was used for detection of ESBL production. The susceptibility to different antibiotics was determined by the disk diffusion method (CLSI). Clonal relatedness was determined by pulsed-field gel electrophoresis (PFGE) and processed by Bionumerics 7.0 software. Statistical analyses were performed using SPSS-16.0. Results: This study showed high prevalence of resistance to ampicillin and cefpodoxim (98.1 and 92.3%). Fifty-two of the 84 isolates were identified as ESBL producers. Only colistin and tigecycline remained active against all isolates tested. The PFGE identified eight distinct pulsotypes: A (N=9), B (N=10), C (N=2), D (N=5), E (N=9), F (N=15), G (N=1) and H (N=1). The PFGE profiles A, B and F were believed to be endemic (specially clone F that was dominant across different wards of the hospitals and appeared to be endemic) in the ICU, emergency, pediatric and infection area throughout the years. Conclusion: Early and timely detection of ESBL-producing A. baumannii clones is useful for preventing their spread within the hospital. PFGE analysis is helpful for detection of common strains in different wards and prevention of further spread of these pulsotypes to other hospital environment.