title: Evaluation of the Enterococcus faecalis Biofilm-Associated Virulence Factors AhrC and Eep in Rat Foreign Body Osteomyelitis and In Vitro Biofilm-Associated Antimicrobial Resistance.
abstract: Enterococcus faecalis can cause healthcare-associated biofilm infections, including those of orthopedic devices. Treatment of enterococcal prosthetic joint infection is difficult, in part, due to biofilm-associated antimicrobial resistance. We previously showed that the E. faecalis OG1RF genes ahrC and eep are in vitro biofilm determinants and virulence factors in animal models of endocarditis and catheter-associated urinary tract infection. In this study, we evaluated the role of these genes in a rat acute foreign body osteomyelitis model and in in vitro biofilm-associated antimicrobial resistance. Osteomyelitis was established for one week following the implantation of stainless steel orthopedic wires inoculated with E. faecalis strains OG1RF, ΩahrC, and ∆eep into the proximal tibiae of rats. The median bacterial loads recovered from bones and wires did not differ significantly between the strains at multiple inoculum concentrations. We hypothesize that factors present at the infection site that affect biofilm formation, such as the presence or absence of shear force, may account for the differences in attenuation in the various animal models we have used to study the ΩahrC and ∆eep strains. No differences among the three strains were observed in the planktonic and biofilm antimicrobial susceptibilities to ampicillin, vancomycin, daptomycin, linezolid, and tetracycline. These findings suggest that neither ahrC nor eep directly contribute to E. faecalis biofilm-associated antimicrobial resistance. Notably, the experimental evidence that the biofilm attachment mutant ΩahrC displays biofilm-associated antimicrobial resistance suggests that surface colonization alone is sufficient for E. faecalis cells to acquire the biofilm antimicrobial resistance phenotype.
authors.affiliation: Department of Microbiology, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors.forename: Kristi L
authors.initials: KL
authors.lastname: Frank
authors.affiliation: Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Paschalis
authors.initials: P
authors.lastname: Vergidis
authors.affiliation: Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Cassandra L
authors.initials: CL
authors.lastname: Brinkman
authors.affiliation: Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Kerryl E
authors.initials: KE
authors.lastname: Greenwood Quaintance
authors.affiliation: Department of Microbiology, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors.forename: Aaron M T
authors.initials: AM
authors.lastname: Barnes
authors.affiliation: Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Jayawant N
authors.initials: JN
authors.lastname: Mandrekar
authors.affiliation: Department of Microbiology, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Schlievert
authors.affiliation: Department of Microbiology, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors.forename: Gary M
authors.initials: GM
authors.lastname: Dunny
authors.affiliation: Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, United States of America; Division of Infectious Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, United States of America.
authors.forename: Robin
authors.initials: R
authors.lastname: Patel
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D004352:Drug Resistance, Microbial; D013293:Enterococcus faecalis / Q000187:drug effects / Q000502:physiology*; D005547:Foreign Bodies; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy / Q000378:metabolism* / Q000382:microbiology; D066298:In Vitro Techniques; D008297:Male; D010019:Osteomyelitis / Q000188:drug therapy / Q000378:metabolism* / Q000382:microbiology; D051381:Rats; D017208:Rats, Wistar; D037521:Virulence Factors / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D037521:Virulence Factors