Expression of the adeB gene and responsiveness to 1-(1-naphthylmethyl)-piperazine and phenylalanyl-arginyl-β-naphthylamide in clinical isolates of acinetobacter baumannii

摘要

Sir,AdeABC, a resistance-nodulation-cell division (RND)-type efflux pump, is an attractive research target as a cause of multiple antibiotic resistance in Acinetobocter baumannii. The overexpression of the adeB gene encoding the AdeB efflux protein has previously been associated with multidrug resistance in various A baumannii strains.1"3 These reports led us to perform a study in a group of clinical isolates of A baumannii, to assess the relative expression of the adeB gene and responsiveness to the potential efflux pump inhibitors (EPIs), l-(l-naphthylmethyl)-piperazine (NMP) and phenytalanyl-arginyl-beta-naphthylamide (PA|3N). Fourteen multidrug-resistant A baumannii isolates obtained from different patients in an intensive care unit and grouped previously into three clones were included in the study (Table 1).A baumannii ATCC 19606, A baumannii SBMox2, A baumannii U10247 and Escherichia coli ATCC 25922 were used as reference strains. The MICs of ciprofloxacin, gentamicin, erythromycin, chloram-phenicol, trimethoprim and tetracycline were determined by the broth microdilution test in the absence and presence of NMP and PAbetaN, at final concentrations of 100 mg/L