Objective: To obtain and compare heterotrophic plate count (HPC) and Legionella spp. growing in tap water cultures from newly installed electronic faucets and existing manual faucets. Efficacy of chlorine dioxide disinfection of each type of contaminated faucet was also assessed.
Methods: Water samples were collected from 20 newly installed electronic faucets and 20 manual faucets on three hospital wards at The Johns Hopkins Hospital. Manual faucets were in rooms adjacent to the electronic faucets and received water from the same source. Coincidentally, cultures were obtained after a brief loss of water pressure in the entire hospital system, which historically increases both HPC and Legionella spp. recovery from tap water. Water samples were collected on separate days between December 15, 2008 and January 29, 2009. Four electronic faucets were dismantled, and faucet components were cultured. Legionella spp. and HPC cultures of water samples and faucet components were performed utilizing standard methods. Chlorine dioxide remediation of the water system was performed on January 12th and 13th, 2009.
Results: 54 (50%) of 108 water cultures from electronic faucets grew Legionella spp. compared to 11 (15%) of 75 water cultures from manual faucets (p < 0.001). 15 (26%) of 58 electronic faucet HPC cultures grew > 500 colony forming units (CFU)/ml as compared to 6 (13%) of 45 manual faucet cultures (p = 0.10). After chlorine dioxide remediation, 4 (14%) of 28 electronic faucet and 1 (3%) of 30 manual faucet water cultures grew Legionella spp. (p = 0.14), and 8 (29%) electronic faucet and 2 (7%) manual faucet cultures had HPC growth (p = 0.03). Prior to chlorine dioxide remediation, all 12 (100%) of the faucet components from two electronic faucets had positive Legionella spp. growth and 11 (92%) had positive HPC growth. Post remediation, 2 (15%) of the 13 electronic faucet components had positive Legionella spp. growth and all 13 (100%) had positive HPC growth. The most significant growth was from the hot water check valves before and after chlorine dioxide remediation.
Conclusions: Electronic faucets were more likely to become contaminated with Legionella spp. and other bacteria after water system disruption. Electronic faucets were less likely to be disinfected after chlorine dioxide remediation. Electronic faucet components may provide points of concentrated bacterial growth. These findings led to removal of all electronic faucets from clinical areas in our institution.