Genes encoding a novel multidrug efflux pump, AadT, from the Drug:H+antiporter 2 family, were discovered inAcinetobactermultidrug resistance plasmids. Here, we profiled the antimicrobial resistance potential, and examined the distribution of these genes.aadThomologs were found in manyAcinetobacterand other Gram-negative species and were typically adjacent to novel variants ofadeAB(C), which encodes a major tripartite efflux pump inAcinetobacter. The AadT pump decreased bacterial susceptibility to at least eight diverse antimicrobials, including antibiotics (erythromycin and tetracycline), biocides (chlorhexidine), and dyes (ethidium bromide and DAPI) and was able to mediate ethidium transport. These results show that AadT is a multidrug efflux pump in theAcinetobacterresistance arsenal and may cooperate with variants of AdeAB(C).