title: Antimicrobial resistance and virulence traits of Enterococcus faecalis from primary endodontic infections.
abstract: OBJECTIVE
  To determine the phenotypic and molecular characteristics of Enterococcus faecalis recovered from primary endodontic infections in Brazilian patients.
  
  
  METHODS
  Twenty isolates of E. faecalis recovered from 43 Brazilian patients with primary endodontic infections were identified by biochemical profiling (API20Strep) and 16S rDNA sequencing. Antimicrobial susceptibility was ascertained by agar dilution, using the recommended protocol of the Clinical and Laboratory Standards Institute (CLSI). PCR with validated primers was used to detect genes associated with antibiotic resistance and specific virulence factors.
  
  
  RESULTS
  All isolates were deemed susceptible to penicillin G, erythromycin and vancomycin. However, nine isolates had a minimum inhibitory concentration of 4μg/mL to vancomycin (the resistance breakpoint). Fourteen isolates (70% of isolates) were also resistant to tetracycline with MICs of >64μg/mL. PCR products for tetracycline resistance genes were detected in test isolates, while erythromycin and vancomycin resistance genes were not evident. Gelatinase, aggregation substance and enteroccocal surface protein genes were detected in 20, 18 and 12 isolates, respectively.
  
  
  CONCLUSIONS
  Endodontic E. faecalis isolates exhibit high level of resistance to tetracycline, an antibiotic that has use in local treatment of dental infections. This opens up a much-needed debate on the role and efficacy of this antibiotic for oral infections. Furthermore, these isolates were shown to possess genes that could contribute to pathogenicity in the pulp cavity.
authors.affiliation: School of Dentistry, Rio de Janeiro State University, Rio de Janeiro, Brazil. ximenes@uerj.br
authors.forename: Renata Ximenes
authors.initials: RX
authors.lastname: Lins
authors.forename: Aurimar
authors.initials: A
authors.lastname: de Oliveira Andrade
authors.forename: Raphael
authors.initials: R
authors.lastname: Hirata Junior
authors.forename: Melanie J
authors.initials: MJ
authors.lastname: Wilson
authors.forename: Michael A O
authors.initials: MA
authors.lastname: Lewis
authors.forename: David W
authors.initials: DW
authors.lastname: Williams
authors.forename: Rivail Antonio Sergio
authors.initials: RA
authors.lastname: Fidel
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000032:analysis; D001431:Bacteriological Techniques; D003788:Dental Pulp Diseases / Q000382:microbiology*; D024881:Drug Resistance, Bacterial; D013293:Enterococcus faecalis / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D004917:Erythromycin / Q000494:pharmacology; D018093:Gelatinases / Q000032:analysis; D020869:Gene Expression Profiling; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology*; D008565:Membrane Proteins / Q000032:analysis; D008826:Microbial Sensitivity Tests; D010400:Penicillin G / Q000494:pharmacology; D010641:Phenotype; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013753:Tetracycline Resistance; D014640:Vancomycin / Q000494:pharmacology; D014774:Virulence; D037521:Virulence Factors / Q000032:analysis
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D008565:Membrane Proteins; D012336:RNA, Ribosomal, 16S; D037521:Virulence Factors; C065937:aggregation substance, Enterococcus faecalis; C116707:enterococcal surface protein, esp; D004917:Erythromycin; D014640:Vancomycin; D018093:Gelatinases; D010400:Penicillin G
keywords: Antimicrobial susceptibility; Endodontic infection; Enterococcus faecalis; Genotype