Relative Gene Expression of RND-Type Efflux Pumps in Tigecycline Resistant Acinetobacter Baumannii Isolated from Training Hospitals in Tehran, Iran

Background: Appearance of multi-drug resistance (MDR) Acinetobacter baumannii imposes limitation on antibiotic therapy in patients. Detection of MDR A. baumannii can play a crucial role to prevent MDR strains spreading in hospitals. The aim of this study was determination the efflux pumps gene expression in tigecyclin resistance strains in collected isolates from selected training hospitals in Tehran, Iran.  Materials and Methods: In this cross sectional study, A. baumannii was collected from July to February 2014. Tigecycline susceptibility testing has been prepared according to CLSI guide- lines after identification. Active efflux pumps have been detected by Carbonyl cyanide m-chlorophenyl hydrazone (CCCP) as an efflux pumps inhibitor. Gene expressions of these efflux pumps have been determined by Real- Time PCR. Results: In this study 80 A. baumannii have been confirmed by conventional phenotypic methods. Tigecyclin resistant was confirmed according to antibiotic susceptibility testing results. The results of CCCP indicated that 22.5% of tigecycline resistant A. baumannii could include active efflux pumps. The results of Real- Time PCR indicated that abeM gene expression has been observed in the most of CCCP positive A. baumannii and adeB has been observed in the minimum number of strains. Conclusion According to the results of this study,Efflux pumps can play an important role in appearance of cross resistance and make MDR strains. Thus, the detection of antibiotic resistance related to active efflux pumps may be crucial to find a composition with efflux pump inhibitor effect by clinical usage.