Efficacy of New Point-of-Use Water Filters To Prevent Exposure to Legionella and Waterborne Bacteria

BACKGROUND/OBJECTIVES: Legionella and other waterborne pathogens are the cause of serious hospital-acquired infections, particularly in the immunocompromised patient. The disinfection of water systems to prevent Legionnairesʹ disease has been shown to be an effective approach to prevention. Current guidelines from the Centers for Disease Control and Prevention (CDC) suggest that no Legionella should be detected from water outlets in hospital units housing transplant patients. We evaluated the ability of point-of-use filters to eliminate Legionella and other pathogens from water. METHODS: A hospital building (non-patient care) was colonized with Legionella pneumophila, serogroup 1 (mean 25 CFU/mL). Hot water samples of 100 mL were collected from 7 faucets (four with filters and three without) immediately and after a 1-minute flush. Samples were collected every 2–3 days for 1 week. This cycle was repeated for 12 weeks. Samples were cultured for Legionella, total heterotrophic bacteria (HPC) and Mycobacterium spp. RESULTS: A total of 594 samples were collected over 12 cycles. No Legionella or M. gordonae were isolated from the faucets with filters between Time (T) =0 and T=8d, whereas the mean concentration of L. pneumophila and M. gordonae from the control faucets was 104.5 CFU/mL and 0.44 CFU/mL, respectively. The filters achieved a greater than 99% reduction in HPC bacteria in the immediate and post-flush samples. CONCLUSIONS: Point-of-use filters completely eliminated L. pneumophila and M. gordonae from hot water samples. Point-of-use filter units could be used to prevent exposure of high-risk patients to waterborne pathogens without modification or disinfection of the entire potable water system.