title: Characterization of Class IIa Bacteriocin Resistance in Enterococcus faecium.
abstract: Vancomycin-resistant enterococci, particularly resistantEnterococcus faecium, pose an escalating threat in nosocomial environments because of their innate resistance to many antibiotics, including vancomycin, a treatment of last resort. Many class IIa bacteriocins strongly target these enterococci and may offer a potential alternative for the management of this pathogen. However,E. faecium's resistance to these peptides remains relatively uncharacterized. Here, we explored the development of resistance ofE. faeciumto a cocktail of three class IIa bacteriocins: enterocin A, enterocin P, and hiracin JM79. We started by quantifying the frequency of resistance to these peptides in four clinical isolates ofE. faeciumWe then investigated the levels of resistance ofE. faecium6E6 mutants as well as their fitness in different carbon sources. In order to elucidate the mechanism of resistance ofE. faeciumto class IIa bacteriocins, we completed whole-genome sequencing of resistant mutants and performed reverse transcription-quantitative PCR (qRT-PCR) of a suspected target mannose phosphotransferase (ManPTS). We then verified this ManPTS's role in bacteriocin susceptibility by showing that expression of the ManPTS inLactococcus lactisresults in susceptibility to the peptide cocktail. Based on the evidence found from these studies, we conclude that, in accord with other studies inE. faecalisandListeria monocytogenes, resistance to class IIa bacteriocins inE. faecium6E6 is likely caused by the disruption of a particular ManPTS, which we believe we have identified.
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Geldart
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, USA yiannis@umn.edu.
authors.forename: Yiannis N
authors.initials: YN
authors.lastname: Kaznessis
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001430:Bacteriocins / Q000494:pharmacology; D003001:Cloning, Molecular; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D016984:Enterococcus faecium / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D015870:Gene Expression; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology; D006801:Humans; D013294:Lactococcus lactis / Q000235:genetics / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D009154:Mutation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D065507:Vancomycin-Resistant Enterococci / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001430:Bacteriocins; D011994:Recombinant Proteins; C107799:enterocin A; C417717:enterocin P; C522689:hiracin JM79; D017853:Phosphotransferases (Alcohol Group Acceptor); C032922:mannokinase
keywords: Enterococcus; antibiotic resistance; bacteriocins