The roles of efflux pumps from different superfamilies in the surface-associated motility and virulence of Acinetobacter baumannii ATCC 17978 [Mechanisms of Resistance]

While the relationship between Acinetobacter baumannii efflux pumps and antimicrobial resistance is well-documented, less is known about the involvement of these proteins in the pathogenicity of this nosocomial pathogen. In previous work, we identified the AbaQ MFS efflux pump and demonstrated its participation in the motility and virulence of A. baumannii. In the present study, we examined the role in these processes of A. baumannii transporters belonging to different superfamilies of efflux pumps. Genes encoding known or putative permeases belonging to efflux pump superfamilies other than MFS were selected and the corresponding knockouts constructed. The antimicrobial susceptibilities of these mutants were consistent with previously reported data. In mutants of A. baumannii strain ATCC 17978 carrying inactivated genes encoding the efflux pumps A1S_2736 (RND), A1S_3371 (MATE) and A1S_0710 (SMR) as well as the newly described ABC permeases A1S_1242 and A1S_2622, both surface-associated motility and virulence were reduced compared to the parental strain. However, inactivation of the genes encoding the known ABC permeases A1S_0536 and A1S_1535, the newly identified putative ABC permeases A1S_0027 and A1S_1057, or the PACE transporters A1S_1503 and A1S_2063 had no effects on bacterial motility or virulence. Our results demonstrate the involvement of antimicrobial transporters belonging at least to five of the six known efflux pump superfamilies in both surface-associated motility and virulence in A. baumannii ATCC 17978.

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