title: Genome-Wide Identification of Antimicrobial Intrinsic Resistance Determinants inStaphylococcus aureus.
abstract: The emergence of antimicrobial resistance severely threatens our ability to treat bacterial infections. While acquired resistance has received considerable attention, relatively little is known of intrinsic resistance that allows bacteria to naturally withstand antimicrobials. Gene products that confer intrinsic resistance to antimicrobial agents may be explored for alternative antimicrobial therapies, by potentiating the efficacy of existing antimicrobials. In this study, we identified the intrinsic resistome to a broad spectrum of antimicrobials in the human pathogen,Staphylococcus aureus. We screened the Nebraska Transposon Mutant Library of 1920 single-gene inactivations inS. aureusstrain JE2, for increased susceptibility to the anti-staphylococcal antimicrobials (ciprofloxacin, oxacillin, linezolid, fosfomycin, daptomycin, mupirocin, vancomycin, and gentamicin). Sixty-eight mutants were confirmed byE-test to display at least twofold increased susceptibility to one or more antimicrobial agents. The majority of the identified genes have not previously been associated with antimicrobial susceptibility inS. aureus. For example, inactivation of genes encoding for subunits of the ATP synthase,atpA,atpB,atpGandatpH, reduced the minimum inhibitory concentration (MIC) of gentamicin 16-fold. To elucidate the potential of the screen, we examined treatment efficacy in theGalleria mellonellainfection model. Gentamicin efficacy was significantly improved, when treating larvae infected with theatpAmutant compared to wild type cells with gentamicin at a clinically relevant concentration. Our results demonstrate that many gene products contribute to the intrinsic antimicrobial resistance ofS. aureus. Knowledge of these intrinsic resistance determinants provides alternative targets for compounds that may potentiate the efficacy of existing antimicrobial agents against this important pathogen.
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark.
authors.forename: Martin
authors.initials: M
authors.lastname: Vestergaard
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark.
authors.forename: Bingfeng
authors.initials: B
authors.lastname: Leng
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark.
authors.forename: Jakob
authors.initials: J
authors.lastname: Haaber
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark.
authors.forename: Martin S
authors.initials: MS
authors.lastname: Bojer
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark.
authors.forename: Christina S
authors.initials: CS
authors.lastname: Vegge
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark.
authors.forename: Hanne
authors.initials: H
authors.lastname: Ingmer
keywords: Galleria mellonella; Staphylococcus aureus; antimicrobial agents; intrinsic resistance; potentiator targets