Characterization of Enterococcus faecalis associated with root canal failures: Virulence and resistance profile

Enterococcus faecalis is a facultative anaerobe frequently associated with chronic root canal infections. Its virulence factors and antimicrobial resistance complicate its elimination. This research aims to analyze the virulence factors and antibiotic resistance profiles of E. faecalis isolates derived from unsuccessful root canal procedures.

A cross-sectional study was conducted with 50 patients who required nonsurgical retreatment due to previous root canal therapy failures. The samples were assessed for biofilm formation and antibiotic resistance, while the production of gelatinase and hemolysin was evaluated through the standard microbiological methods. The correlation between biofilm production and antimicrobial resistance was analyzed using Pearson's correlation coefficient.

Among the 50 E. faecalis isolates, 66% demonstrated biofilm formation, with 24% categorized as strong biofilm producers. Antibiotic susceptibility testing indicated complete resistance to metronidazole, whereas all isolates were sensitive to amoxicillin-clavulanic acid, vancomycin, and piperacillin-tazobactam. Significant resistance rates were observed for ampicillin (44%), erythromycin (60%), tetracycline (64%), and ciprofloxacin (66%). A strong negative correlation (r = -0.88) was found between biofilm formation and antibiotic susceptibility, suggesting that strains capable of biofilm production exhibited greater resistance to antibiotics.

The research underscores the critical importance of the pathogenic traits of E. faecalis, especially its biofilm production potential, in the persistent nature of root canal infections and its association with antibiotic resistance. These results highlight the necessity for enhanced disinfection methods and the exploration of alternative treatment strategies aimed at biofilms to improve the therapeutic outcomes and reduce the risk of reinfection after root canal procedures.