Potential for nosocomial transmission of Enterococcus faecalis from surfaces in dental operatories

Aim: To assess the potential for nosocomial transmission of Enterococcus faecalis during root canal treatment by measuring its occurrence on surfaces in dental operatories in relation to the efficacy of disinfection routines.

Methodology: Eight dental clinics (two endodontic specialist clinics and six general dentistry clinics) were included. Bacterial sampling was conducted in duplicate after root canal treatment and collected before and after disinfection from four surfaces expected to be frequently disinfected and six surfaces expected to be occasionally disinfected.

Results: A total of 320 samples were collected. Overall, 40.6% (n = 130) exhibited bacterial growth, mostly consisting of environmental bacteria (36.3%) and to a lesser extent of bacteria from salivary contamination (3.4%). Only three surfaces, all of which were probably seldomly disinfected, were positive for E. faecalis (0.9%). Disinfection routines resulted in an increased contamination in the majority of general dentistry clinics: 64% (32/50) of the surfaces were contaminated prior to and 70% (35/50) after disinfection. Conversely, disinfection of surfaces in the specialist clinics reduced contamination levels by 10%.

Conclusions: The origin of E. faecalis in secondary root canal infections remains unclear, as the potential for nosocomial transmission of enterococci from environmental surfaces in dental surgeries appears to be very small. The incorrect or ineffective disinfection procedures in general dentistry clinics needs to be addressed to counteract the risk for bacterial transmission in dental operatories.