RESUMO
OBJECTIVE: To investigate the role of AdeABC efflux pump in carbapenems resistance of Acinetobacter baumannii in light of the phenotype and genetype of the efflux pump. METHODS: The phenotype of the efflux pump was detected in 138 clinical isolates of A.baumannii using the efflux pump inhibitor carbonyl cyanide 3-chlorophenylhydrazone (CCCP). The mRNA expression of pump-encoding gene adeB in the strains was detected using quantitative real-time RT-PCR. RESULTS: Of the 138 strains, 28 showed positivities for AdeABC efflux pump identified by Mueller-Hinton Broth with CCCP. Of the 39 strains resistant to meropenem, 15 (38.4%) showed positive results in CCCP assay, a rate significantly higher than that among the 99 sensitive strains (13.1%, 13/99) (X(2)=12.477(b), P=0.01). The mRNA expression of efflux pump-encoding gene adeB was detected by real-time RT-PCR at a level of 0.899∓∓1.172 in meropenem-sensitive strains, significantly lower than the level of 21.101∓∓21.443 in meropenem-resistant strains (t=4.403, P=0.000). CONCLUSIONS: Efflux plays a role in carbapenems resistance in the clinical isolates of A. baumannii. The AdeABC efflux pump may be an important factor in reducing carbapenems sensitivity in A. baumannii.
