title: Antimicrobial Susceptibility and Characterization of Virulence Genes of Enterococcus faecalis Isolates from Teeth with Failure of the Endodontic Treatment.
abstract: BACKGROUND
  The aim of this study was to investigate the prevalence of virulence factors and the antimicrobial resistance of Enterococcus faecalis isolates of teeth with failure of the endodontic treatment.
  
  
  METHODS
  Twenty root canal samples were collected from teeth with apical periodontitis. E. faecalis was firstly identified based on phenotypic features and then by 16S ribosomal RNA gene sequencing. The antimicrobial susceptibility was determined by the minimum inhibitory concentration (MIC) of amoxicillin, amoxicillin + clavulanate, azithromycin, benzylpenicillin, ciprofloxacin, clindamycin, chloramphenicol, doxycycline, erythromycin, gentamicin, metronidazole, moxifloxacin, rifampicin, tetracycline, and vancomycin using the E test method. Virulence factors (ace, asa, asa373, cylA, efaA, esp, and gelE) were detected by polymerase chain reaction assay.
  
  
  RESULTS
  Amoxicillin + clavulanate was effective against all strains. Intermediate and total resistance was found against the majority of the tested antimicrobials. The susceptibility of some microorganisms to some antimicrobial agents changed according to the evaluation time. MIC50 and MIC90 also varied according to the evaluation time. In relation to the virulence factors of the E faecalis isolates, ace was detected in 100% of the strains, asa (60%), asa373 (15%), efaA (95%), esp (70%), and gelE (75%), whereas cylA was not detected.
  
  
  CONCLUSIONS
  It was concluded that E. faecalis isolates from persistent endodontic infections showed varied degrees of intermediate/total resistance to several antimicrobial agents, with amoxicillin + clavulanate being the most effective agent. Moreover, the strains showed different patterns for virulence gene detection.
authors.affiliation: Department of Restorative Dentistry, Endodontic Division, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Marlos
authors.initials: M
authors.lastname: Barbosa-Ribeiro
authors.affiliation: Department of Restorative Dentistry, Endodontic Division, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Adriana
authors.initials: A
authors.lastname: De-Jesus-Soares
authors.affiliation: Department of Restorative Dentistry, Endodontic Division, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Alexandre A
authors.initials: AA
authors.lastname: Zaia
authors.affiliation: Department of Restorative Dentistry, Endodontic Division, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Caio C R
authors.initials: CC
authors.lastname: Ferraz
authors.affiliation: Department of Restorative Dentistry, Endodontic Division, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: José F A
authors.initials: JF
authors.lastname: Almeida
authors.affiliation: Department of Restorative Dentistry, Endodontic Division, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil. Electronic address: bpgomes@unicamp.br.
authors.forename: Brenda P F A
authors.initials: BP
authors.lastname: Gomes
mesh_terms: D000328:Adult; D019980:Amoxicillin-Potassium Clavulanate Combination / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003786:Dental Pulp Cavity / Q000382:microbiology*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D005260:Female; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D017211:Treatment Failure; D014774:Virulence / Q000235:genetics*; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D037521:Virulence Factors; D019980:Amoxicillin-Potassium Clavulanate Combination
keywords: Bacteria; Enterococcus faecalis; microbial sensitivity tests; virulence factor