title: Beta-lactamic resistance profiles in Porphyromonas, Prevotella, and Parvimonas species isolated from acute endodontic infections.
abstract: BACKGROUND
  Susceptibility to beta-lactamic agents has changed among anaerobic isolates from acute endodontic infections. The aim of the present study was to determine the prevalence of the cfxA/cfxA2 gene in Prevotella spp., Porphyromonas spp., and Parviomonas micra strains and show its phenotypic expression.
  
  
  METHODS
  Root canal samples from teeth with acute endodontic infections were collected and Porphyromonas, Prevotella, and Parvimonas micra strains were isolated and microbiologically identified with conventional culture techniques. The susceptibility of the isolates was determined by the minimum inhibitory concentration of benzylpenicillin, amoxicillin, and amoxicillin + clavulanate using the E-test method (AB BIODISK, Solna, Sweden). The presence of the cfxA/cfxA2 gene was determined through primer-specific polymerase chain reaction. The nitrocefin test was used to determine the expression of the lactamase enzyme.
  
  
  RESULTS
  Prevotella disiens, Prevotella oralis, Porphyromonas gingivalis, and P. micra strains were susceptible to benzylpenicillin, amoxicillin, and amoxicillin + clavulanate. The cfxA/cfxA2 gene was detected in 2 of 29 isolates (6.9%). Simultaneous detection of the cfxA/cfxA2 gene and lactamase production was observed for 1 Prevotella buccalis strain. The gene was in 1 P. micra strain but was not expressed. Three strains were positive for lactamase production, but the cfxA/cfxA2 gene was not detected through polymerase chain reaction.
  
  
  CONCLUSIONS
  There is a low prevalence of the cfxA/cfxA2 gene and its expression in Porphyromonas spp., Prevotella spp., and P. micra strains isolated from acute endodontic infections. Genetic and phenotypic screening must be performed simultaneously to best describe additional mechanisms involved in lactamic resistance for strict anaerobes.
authors.affiliation: Endodontic Division, Department of Conservative Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil. Electronic address: francisco.montagner@ufrgs.br.
authors.forename: Francisco
authors.initials: F
authors.lastname: Montagner
authors.affiliation: Endodontic Division, Department of Semiology and Clinics, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil.
authors.forename: Rogério Castilho
authors.initials: RC
authors.lastname: Jacinto
authors.affiliation: Endodontic Division, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Fernanda Graziela
authors.initials: FG
authors.lastname: Correa Signoretti
authors.affiliation: Endodontic Division, Department of Conservative Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Scheffer de Mattos
authors.affiliation: Endodontic Division, Department of Conservative Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Fabiana Soares
authors.initials: FS
authors.lastname: Grecca
authors.affiliation: Endodontic Division, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Brenda Paula Figueiredo de Almeida
authors.initials: BP
authors.lastname: Gomes
mesh_terms: D000658:Amoxicillin / Q000494:pharmacology; D019980:Amoxicillin-Potassium Clavulanate Combination / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016866:Bacteroidaceae Infections / Q000382:microbiology; D002511:Cephalosporins; D003788:Dental Pulp Diseases / Q000382:microbiology*; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology; D006801:Humans; D007202:Indicators and Reagents; D008826:Microbial Sensitivity Tests; D010400:Penicillin G / Q000494:pharmacology; D010462:Peptostreptococcus / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D017861:Porphyromonas / Q000235:genetics / Q000502:physiology*; D045202:Porphyromonas endodontalis / Q000235:genetics / Q000502:physiology; D016966:Porphyromonas gingivalis / Q000235:genetics / Q000502:physiology; D018720:Prevotella / Q000235:genetics / Q000502:physiology*; D018713:Prevotella intermedia / Q000235:genetics / Q000502:physiology; D045242:Prevotella nigrescens / Q000235:genetics / Q000502:physiology; D018440:beta-Lactam Resistance / Q000235:genetics / Q000502:physiology*; D065093:beta-Lactamase Inhibitors / Q000494:pharmacology; D001618:beta-Lactamases / Q000032:analysis / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D007202:Indicators and Reagents; D065093:beta-Lactamase Inhibitors; D019980:Amoxicillin-Potassium Clavulanate Combination; D000658:Amoxicillin; C462979:cfxA protein, Prevotella; D001618:beta-Lactamases; C021720:nitrocefin; D010400:Penicillin G
keywords: Anaerobic bacteria; E-test; antimicrobial agents; lactamases; nitrocefin; polymerase chain reaction; susceptibility