Resistance-nodulation-cell division type efflux pump AdeDE was identified in acinetobacters belonging to genomic DNA group 3. Inactivation of adeE showed that it may be responsible for reduced susceptibility to amikacin, ceftazidime, chloramphenicol, ciprofloxacin, erythromycin, ethidium bromide, meropenem, rifampin, and tetracycline. However, unlike what was found for other similar efflux systems, the open reading frame for the outer membrane component was not found downstream of the adeDE gene cluster.Acinetobacter species, especially genomic DNA group (GDG) 3, are important nosocomial pathogens in Hong Kong (5). The therapy of Acinetobacter infections can be complicated by multidrug resistance to a range of antimicrobial agents (1). Resistance-nodulation-cell division (RND) type efflux pumps can be responsible for a wide substrate specificity in gramnegative bacteria. AdeABC, shown to contribute to multidrug resistance in Acinetobacter baumannii (GDG 2) by Magnet et al., is the only published efflux system in Acinetobacter (2). The three clustering genes adeA, adeB, and adeC were identified as encoding the membrane fusion, multidrug transporter, and outer membrane components characteristic of the RND efflux pump family, respectively (2). We used the degenerate primers described by these authors to detect adeB-like sequence in acinetobacters isolated from clinical specimens at Prince of Wales Hospital, Hong Kong. An amplicon (1.2 kb) was generated from a 1997 blood culture isolate (strain 4365) belonging to GDG 3. The amplicon was then sequenced, and the theoretical translation revealed 50% amino acid identity to AdeB and 46 to 62% amino acid identity (BlastP; European Bioinformatics Institute, Cambridge, United Kingdom) to other members of the RND efflux protein family. Genome walking utilizing the commercial kit GenomeWalker (BD Biosciences Clontech) was employed to clone the flanking regions of the amplicon. After six rounds of walking with primers based on the sequences obtained in the previous round, 11 contigs were generated. Each round of walking was performed at least twice with amplicons obtained from independent PCRs, and at least two clones were picked from each transformation for sequencing in both directions. Alignment of the 11 contigs yielded two complete open reading frames (ORFs) of 1,125 and 3,111 bp, theoretically encoding two peptides with 375 and 1,037 residues, respectively. While the nucleotide sequences failed to match those of any known genes in GenBank, the two peptide sequences have 28 to 53% identity (ClustalW; EBI) to 10 RND efflux systems (Table 1). The theoretical peptides appeared to resemble MexAB and AcrEF most, and the four known conserved motifs of RND proteins were readily aligned and identifiable (6). The ORFs were designated adeD and adeE (Acinetobacter drug efflux), and the products were designated AdeD and AdeE. The ORF immediately downstream of adeE was partially sequenced and, interestingly, the theoretical translation of this partial ORF resulted in a peptide (400 re...

The in-house qPCR test has high sensitivity in detecting GBS colonization. The high negative predictive value helps to avoid unnecessary use of antibiotics in uncolonized women.

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