Interplay between intrinsic and acquired resistance to quinolones in Stenotrophomonas maltophilia

• Published in: Environmental microbiology 2014-05, Vol.16 (5), p.1282-1296
• Main Authors: García‐León, Guillermo, Salgado, Fabiola, Oliveros, Juan Carlos, Sánchez, María Blanca, Martínez, José Luis
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Anti-Bacterial Agents - pharmacology; antibiotic resistance; Antibiotics; bacteria; Bacterial Proteins - metabolism; Bacteriology; batteries; Biological and medical sciences; Drug Resistance, Bacterial - genetics; ecosystems; Fundamental and applied biological sciences. Psychology; gene overexpression; General aspects; genome; Membrane Transport Proteins - metabolism; Microbial ecology; Microbiology; Miscellaneous; mutants; Mutation; phenotype; quinolones; Quinolones - pharmacology; Stenotrophomonas maltophilia; Stenotrophomonas maltophilia - drug effects; Stenotrophomonas maltophilia - genetics; Stenotrophomonas maltophilia - metabolism; transporters
• ISSN: 1462-2912; 1462-2920
• DOI: 10.1111/1462-2920.12408

To analyse whether the mutation‐driven resistance‐acquisition potential of a given bacterium might be a function of its intrinsic resistome, quinolones were used as selective agents and Stenotrophomonas maltophilia was chosen as a bacterial model. S. maltophilia has two elements – SmQnr and SmeDEF – that are important in intrinsic resistance to quinolones. Using a battery of mutants in which either or both of these elements had been removed, the apparent mutation frequency for quinolone resistance and the phenotype of the selected mutants were found to be related to the intrinsic resistome and also depended on the concentration of the selector. Most mutants had phenotypes compatible with the overexpression of multidrug efflux pump(s); SmeDEF overexpression was the most common cause of quinolone resistance. Whole genome sequencing showed that mutations of the SmeRv regulator, which result in the overexpression of the efflux pump SmeVWX, are the cause of quinolone resistance in mutants not overexpressing SmeDEF. These results indicate that the development of mutation‐driven antibiotic resistance is highly dependent on the intrinsic resistome, which, at least for synthetic antibiotics such as quinolones, did not develop as a response to the presence of antibiotics in the natural ecosystems in which S. maltophilia evolved.