The persistence of Stenotrophomonas maltophilia, especially in hospital environments where disinfectants are used intensively, is one of the important factors that allow this opportunistic pathogen to establish nosocomial infections. In the present study, we illustrated that S. maltophilia possesses adaptive resistance to the disinfectant benzalkonium chloride (BAC). This BAC adaptation was abolished in the ΔmfsQ mutant, in which a gene encoding an efflux transporter belonging to the major facilitator superfamily (MFS) was deleted. The ΔmfsQ mutant also showed increased susceptibility to BAC and chlorhexidine gluconate compared with a parental wild type. The expression of mfsQ increased upon exposure to quaternary ammonium compounds, including BAC. Thus, the results of this study suggest that mfsQ plays a role in both adaptive and nonadaptive protection of S. maltophilia from the toxicity of the disinfectant BAC.
Keywords: MFS; Stenotrophomonas maltophilia; composés d’ammonium quaternaire; mfsQ; quaternary ammonium compounds.