Detection of AdeABC efflux pump genes in tetracycline-resistant Acinetobacter baumannii isolates from burn and ventilator-associated pneumonia patients.
OBJECTIVE
Acinetobacter baumannii is the most prevalent nosocomial pathogen which have been emerged in the past three decades worldwide. The aim of this study was to assess the distribution of the AdeABC efflux pump genes, associated with tetracycline resistance in Acinetobacter baumannii isolates collected from burn infection and Ventilator Associated Pneumonia (VAP).


METHODS
Ninety-eight A. baumannii isolates were collected from two different hospitals in Tehran, Iran. Tetracycline susceptibility testing was performed by disk diffusion and agar dilution methods according to the CLSI guidelines. The presence of adeSR, adeB, drug efflux system genes in resistant isolates was assessed by polymerase chain reaction (PCR). Carbonyl cyanide 3-chlorophenylhydrazone (CCCP) was used as a chemical inhibitor agent to assess the contribution of AdeABC efflux pump in tetracycline resistance isolates.


RESULTS
Approximately 48% (47 out of 98) of isolates showed resistance to tetracycline which 14 (14.2%) isolates were corresponded to burn infection and the remaining 33 (33.8%) strains were isolated from VAP. All tetracycline resistant isolates have AdeABC in PCR assay. The reduction of tetracycline MICs by using 50 μg/ml CCCP were as follows: in 18 isolates 2-4 fold reduction in MICs, 26 isolates showed 8 fold reduction,1 isolate showed 16 fold, 1 isolate showed 32 fold and the remaining 1 isolate showed 128 fold reduction in MICs.


CONCLUSIONS
The results showed significant correlation between tetracycline resistance and AdeABC efflux pump genes in resistant A. baumannii isolates.
Department of Microbiology, Iran University of Medical Sciences, Tehran, Iran ; Department of Microbiology, Tehran University of Medical Sciences, Tehran, Iran.
Maryam
M
Beheshti
Department of Microbiology, Iran University of Medical Sciences, Tehran, Iran.
Malihe
M
Talebi
Department of Microbiology, Iran University of Medical Sciences, Tehran, Iran.
Abdollah
A
Ardebili
Department of Microbiology, Tehran University of Medical Sciences, Tehran, Iran.
Abbas
A
Bahador
Department of Microbiology, Iran University of Medical Sciences, Tehran, Iran ; Department of Microbiology, Tehran University of Medical Sciences, Tehran, Iran ; Razi Drug Research Center, Iran University of Medical Sciences, Tehran, Iran.
Abdolaziz Rastegar
AR
Lari
Acinetobacter baumannii; Iran; burns; efflux pump genes; tetracycline; ventilator associated penumonia