title: Enterococcus faecalis from Food, Clinical Specimens, and Oral Sites: Prevalence of Virulence Factors in Association with Biofilm Formation.
abstract: Enterococci have gained significance as the cause of nosocomial infections; they occur as food contaminants and have also been linked to dental diseases. E. faecalis has a great potential to spread virulence as well as antibiotic resistance genes via horizontal gene transfer. The integration of food-borne enterococci into the oral biofilm in-vivo has been observed. Therefore, we investigated the virulence determinants and antibiotic resistance of 97 E. faecalis isolates from the oral cavity, food, and clinical specimens. In addition, phenotypic expression of gelatinase and cytolysin were tested, in-vitro biofilm formation was quantified and isolates were compared for strain relatedness via pulsed field gel electrophoresis (PFGE). Each isolate was found to possess two or more virulence genes, most frequently gelE, efaA, and asa1. Notably, plaque/saliva isolates possessed the highest abundance of virulence genes, the highest levels of phenotypic gelatinase and hemolysin activity and concurrently a high ability to form biofilm. The presence of asa1 was associated with biofilm formation. The biofilm formation capacity of clinical and plaque/saliva isolates was considerably higher than that of food isolates and they also showed similar antibiotic resistance patterns. These results indicate that the oral cavity can constitute a reservoir for virulent E. faecalis strains possessing antibiotic resistance traits and at the same time distinct biofilm formation capabilities facilitating exchange of genetic material.
authors.affiliation: Department of Operative Dentistry and Periodontology, Center for Dental Medicine, Medical Center, University of Freiburg Freiburg, Germany.
authors.forename: Annette C
authors.initials: AC
authors.lastname: Anderson
authors.affiliation: Department of Infection Control and Hospital Epidemiology, Institute for Environmental Health Sciences and Hospital Infection Control, Medical Center, University of Freiburg Freiburg, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Jonas
authors.affiliation: Bavarian Health and Food Safety Authority Oberschleissheim, Germany.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Huber
authors.affiliation: Department of Operative Dentistry and Periodontology, Center for Dental Medicine, Medical Center, University of Freiburg Freiburg, Germany.
authors.forename: Lamprini
authors.initials: L
authors.lastname: Karygianni
authors.affiliation: Department of Operative Dentistry and Periodontology, Center for Dental Medicine, Medical Center, University of Freiburg Freiburg, Germany.
authors.forename: Johan
authors.initials: J
authors.lastname: Wölber
authors.affiliation: Department of Operative Dentistry and Periodontology, Center for Dental Medicine, Medical Center, University of Freiburg Freiburg, Germany.
authors.forename: Elmar
authors.initials: E
authors.lastname: Hellwig
authors.affiliation: Department of Periodontology, Philipps-University of Marburg Marburg, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Arweiler
authors.affiliation: Department of Medical Biometry and Statistics, Center for Medical Biometry and Medical Informatics, Medical Center, University of Freiburg Freiburg, Germany.
authors.forename: Kirstin
authors.initials: K
authors.lastname: Vach
authors.affiliation: Department of Medical Microbiology and Hygiene, Center for Microbiology and Hygiene, Medical Center, University of Freiburg Freiburg, Germany.
authors.forename: Annette
authors.initials: A
authors.lastname: Wittmer
authors.affiliation: Department of Operative Dentistry and Periodontology, Center for Dental Medicine, Medical Center, University of Freiburg Freiburg, Germany.
authors.forename: Ali
authors.initials: A
authors.lastname: Al-Ahmad
keywords: PFGE; antibiotic susceptibility; biofilm formation; enterococci; oral cavity; virulence factors