Point-of-use water filtration reduces healthcare-associated infections in bone marrow transplant recipients

Gram-negative bacteria (GNB) are major contributors to serious morbidity and mortality in hospitalized patients. Immunocompromised individuals, such as recipients of bone marrow transplants (BMT) are at particularly high risk. Outbreaks of infection with GNB have been linked to hospital water. We sought to determine whether point-of-use (POU) water filtration might result in decreased risk of infection in hospitalized BMT recipients in the absence of any recognized outbreak. Unfiltered water was sampled from taps in the BMT unit of a major U.S. teaching hospital, and cultured at a reference laboratory for selected waterborne pathogens. POU bacterial-retentive filters (0.2 µm) were installed on sinks, showers and ice machines throughout the unit, and replaced every 14 days. Infection rates were tracked over a nine-month period, and compared with rates for a 16-month period prior to POU filtration. Unfiltered water samples from 50% (2 of 4) outlets sampled grew P. aeruginosa (2 of 4) and S. maltophilia (1 of 4). Clinical infection rates in the unit were significantly reduced from 1.4 total and 0.4 GNB infections per 100 patient days in the period prior to POU filtration to 0.18 total and 0.09 GNB infections per 100 patient days (p=0.0068 and p=0.0431, respectively) in the 9-month period for which filters were in place. No infections were noted in eight of those nine months; and, all infections during the POU filtration period were due to non-waterborne organisms. POU water filtration may significantly reduce infection rates in BMT recipients in the absence of any recognized outbreak.