title: The Two-Component System ChtRS Contributes to Chlorhexidine Tolerance in Enterococcus faecium.
abstract: Enterococcus faeciumis one of the primary causes of nosocomial infections. Disinfectants are commonly used to prevent infections with multidrug-resistantE. faeciumin hospitals. Worryingly,E. faeciumstrains that exhibit tolerance to disinfectants have already been described. We aimed to identify and characterizeE. faeciumgenes that contribute to tolerance to the disinfectant chlorhexidine (CHX). We used a transposon mutant library, constructed in a multidrug-resistantE. faeciumbloodstream isolate, to perform a genome-wide screen to identify genetic determinants involved in tolerance to CHX. We identified a putative two-component system (2CS), composed of a putative sensor histidine kinase (ChtS) and a cognate DNA-binding response regulator (ChtR), which contributed to CHX tolerance inE. faeciumTargetedchtRandchtSdeletion mutants exhibited compromised growth in the presence of CHX. Growth of thechtRandchtSmutants was also affected in the presence of the antibiotic bacitracin. The CHX- and bacitracin-tolerant phenotype ofE. faeciumE1162 was linked to a unique, nonsynonymous single nucleotide polymorphism inchtRTransmission electron microscopy showed that upon challenge with CHX, the ΔchtRand ΔchtSmutants failed to divide properly and formed long chains. Normal growth and cell morphology were restored when the mutations were complemented intransMorphological abnormalities were also observed upon exposure of the ΔchtRand ΔchtSmutants to bacitracin. The tolerance to both chlorhexidine and bacitracin provided by ChtRS inE. faeciumhighlights the overlap between responses to disinfectants and antibiotics and the potential for the development of cross-tolerance for these classes of antimicrobials.
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Guzmán Prieto
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Jessica
authors.initials: J
authors.lastname: Wijngaarden
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Johanna C
authors.initials: JC
authors.lastname: Braat
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Malbert R C
authors.initials: MRC
authors.lastname: Rogers
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Eline
authors.initials: E
authors.lastname: Majoor
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Ellen C
authors.initials: EC
authors.lastname: Brouwer
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Xinglin
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Jumamurat R
authors.initials: JR
authors.lastname: Bayjanov
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Marc J M
authors.initials: MJM
authors.lastname: Bonten
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Rob J L
authors.initials: RJL
authors.lastname: Willems
authors.affiliation: Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands w.vanschaik@umcutrecht.nl.
authors.forename: Willem
authors.initials: W
authors.lastname: van Schaik
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001414:Bacitracin / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D002710:Chlorhexidine / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000235:genetics*; D004202:Disinfectants / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D016984:Enterococcus faecium / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D000071677:Histidine Kinase / Q000235:genetics* / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D020641:Polymorphism, Single Nucleotide / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D004202:Disinfectants; D001414:Bacitracin; D000071677:Histidine Kinase; D002710:Chlorhexidine
keywords: Enterococcus; bacitracin; biocides; chlorhexidine; disinfectants; tolerance