Antibiotic Resistance and Virulence Genes in Enterococcus faecalis Isolated From Human Dental Plaque

Background Enterococcus faecalis causing serious infections have many virulence factors to be involved in the pathogenesis. Its pathogenicity ranges from life-threatening diseases in compromised patients to less severe features, such as infection of acquired root canals with chronic periodontitis. The aim of the present study was to determine the antibiotic resistance patterns and virulence genes in E. faecalis isolated from human dental plaque. Methods The duration of this study was from October 2017 to March 2018. The samples were collected from dental plaques of 207 Iranian patients according to a standard protocol. Enterococcus faecalis strains were identified and confirmed by microbiological and biochemical tests. Antimicrobial susceptibility was ascertained by disk agar diffusion, using the recommended protocol of the Clinical and Laboratory Standards Institute. Finally, polymerase chain reaction for the detection of E. faecalis virulence genes (efaA, ahrC, and eep) was performed with specific primers. Results A total of 43 (76.7%) E. faecalis were identified of which 5 (11.6%), 4 (9.3%), and 1 (2.3%) isolates were resistant against linezolid, chloramphenicol, and teicoplanin, respectively, whereas all isolates were susceptible to penicillin G and amoxicillin-clavulanic acid. Most of the E. faecalis isolates were contained efaA (65.1%), and the frequencies of eep and ahrC were 44.1% and 34.8%, respectively. Conclusions It was concluded that E. faecalis isolated from dental plaques might represent a reservoir of biofilm encoding genes. Further epidemiological studies are necessary to investigate the status of virulence factors in enterococci isolated from dental plaques.