Adaptive Protection and Cross-Resistance to Antibiotics of Stenotrophomonas maltophilia Mediated by Biocides: Molecular Mechanisms

Stenotrophomonas maltophilia is considered an emerging multidrug-resistant opportunistic pathogen. The prevalence of S. maltophilia community and healthcare-associated infections is increasing, particularly in immunocompromised individuals. The persistence of S. maltophilia in healthcare facilities and hospital environments, where biocides are applied intensively to control microbial contamination and infections, is one of the leading factors that enables its transmission. This bacterium has developed both intrinsic and acquired resistance mechanisms to overcome biocide toxicity. In this review, we describe the function and mechanisms of gene regulation of the different biocide resistance genes that have been reported in S. maltophilia to date. The expression of some biocide resistance genes is controlled by inducible transcrip¬tional regulators, which allow adaptive resistance against biocides. Interestingly, some biocide-inducing genes, such as smeDEF, contribute not only to resistance against biocides but also antibiotics. This raises the concern that the overuse and misuse of biocides in healthcare settings can induce cross-resistance to multiple antibiotics.