In vitro Evaluation of Proton Motive Force-Dependent Efflux Pumps Among Multidrug Resistant Acinetobacter baumannii Isolated From Patients at Tehran Hospitals

AUTHORS

Parisa Nikasa 1 , Ahya Abdi-Ali 1 , * , Azadeh Rahmani-Badi 1 , Arif Al-Hamad 2

1 Department of Biology, Faculty of Science, Al-zahra University, Tehran, IR Iran

2 Divisions of Clinical Microbiology and Infection Prevention and Control, Qatif Central Hospital, Qatif, Saudi Arabia

How to Cite: Nikasa P, Abdi-Ali A, Rahmani-Badi A, Al-Hamad A. In vitro Evaluation of Proton Motive Force-Dependent Efflux Pumps Among Multidrug Resistant Acinetobacter baumannii Isolated From Patients at Tehran Hospitals, Jundishapur J Microbiol. Online ahead of Print ; 6(7):6792. doi: 10.5812/jjm.6792.

ARTICLE INFORMATION

Jundishapur Journal of Microbiology: 6 (7); 6792
Published Online: September 10, 2013
Article Type: Research Article
Received: June 16, 2012
Accepted: August 8, 2012
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Abstract

Background: Multidrug-resistant (MDR) strains of Acinetobacter baumannii have been increasingly reported as a major cause of nosocomial infections, and have created major therapeutic problems worldwide.

Objectives: The aim of the present study was to evaluate the role of proton motive force (PMF)-dependent efflux mechanism in the multiple resistance phenotype of A. baumannii clinical strains.

Materials and Methods: A total of 65 A. baumannii clinical strains were collected from hospitals in Tehran. These were tested for antimicrobial susceptibility using disc agar diffusion and broth microdilution methods. Active efflux was assessed by ethidium bromide accumulation assays. Further evaluations were performed by the determination of the minimum inhibitory concentrations and the accumulation of ciprofloxacin against selected MDR A. baumannii in the presence and absence of carbonyl cyanide m-chlorophenylhydrazone (CCCP), an inhibitor of PMF.

Results: Ninety five percent of strains were MDR, with high rate of resistance to ciprofloxacin (92.3%), gentamicin (89.2%), and ceftazidime (93.8%). Colistin and imipenem were the most effective antibiotics with resistance rates of 1.5% and 44.6%, respectively. MDR strains showed a four-fold reduction in the MIC of ciprofloxacin when tested in the presence of the efflux pump inhibitor. The addition of CCCP led to a significant increase in the accumulation of ethidium bromide and ciprofloxacin.

Conclusions: PMF-dependent efflux mechanism appears to play an important role in the MDR phenotype of A. baumannii clinical strains.

Keywords

Acinetobacter baumannii Multidrug Resistant Efflux Pump Inhibitor Drug Accumulation

© 2013, Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.

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