The nature and epidemiology of OqxAB, a multidrug efflux pump.

Background: OqxAB efflux pump has been found to mediate multidrug resistance (MDR) in various bacteria over the past decades. The updates on the nature and epidemiology of OqxAB efflux pump need to be fully reviewed to broaden our understanding of this MDR determinant.

Methods: A literature search using the keyword of "oqxAB" was conducted in the online databases of Pubmed and ISI Web of Science with no restriction on the date of publication. The 87 publications were included into this review as references due to their close relevance to the nature and/or epidemiology of OqxAB efflux pump.

Results: The gene generally locates on chromosome and/or plasmids flanked by IS26-like elements in clinical isolates of and , conferring low to intermediated resistance to quinoxalines, quinolones tigecycline, nitrofurantoin, several detergents and disinfectants (benzalkonium chloride, triclosan and SDS). It could co-spread with other antimicrobial resistance genes (, and etc.), virulence genes and heavy metal resistance genes ( and operons). Both RarA (activator) and OqxR (repressor) play important roles on regulation of the expression of OqxAB.

Conclusions: The dissemination of gene may pose a great risk on food safety and public health. Further investigation and understanding of the natural functions, horizontal transfer, and regulation mechanism of the OqxAB efflux pump will aid in future strategies of antimicrobial usage.