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.