Bacterial contamination of new dental unit waterlines and efficacy of shock disinfection

Abstract

Background Bacterial contamination of outlet water from dental unit waterlines (DUWLs) may lead to healthcare-associated infection. The aim of this study was to evaluate the contamination of DUWLs from new dental chairs before and after their initial shock disinfection with ICX Renew® and to determine the efficacy of this method of shock disinfection. Methods The microbiological quality of water samples obtained from the DUWLs of 17 new dental chairs installed at the University Hospital of Nancy, France, was assessed. Water samples were collected before and after an initial shock disinfection with one ICX Renew® treatment. Water analysis was used to assess total culturable aerobic bacteria (TCAB) at 22°C and 36°C, Legionella sp., Pseudomonas aeruginosa and total coliforms. Results All the DUWLs (17/17) were contaminated by viable aerobic bacteria (TCAB at 22°C and 36°C > 300 CFU/mL), including P. aeruginosa, before shock disinfection. After shock disinfection with ICX Renew®, 24% of DUWLs (4/17) remained contaminated by aerobic bacteria (TCAB at 36°C > 300 CFU/mL for 3/17) and P. aeruginosa (> 100 CFU/100 mL for 1/17). Conclusions To reduce the contamination of new dental chairs, initial shock disinfection of DUWLs should be performed to remove biofilms and bacteria from the DUWLs. To ensure the security of care, microbiological analysis of outlet water from DUWLs should be systematically performed before the first clinical use of a new dental chair to determine the efficacy of shock disinfection and the agreement of the results with the dental recommendations for water quality. Clinical trial number Not applicable.