Is domestic tap water a risk for infections in neutropenic patients?

Home care has become popular in the management of hemato-oncologic patients. Therefore, we conducted a prospective study to assess whether tap water from the domestic environment of neutropenic patients poses a risk for infections from the waterborne pathogens nontuberculous mycobacteria (NTM), Legionella spp., and Pseudomonas aeruginosa. Tap water samples were taken in the homes of 65 hemato-oncologic patients who were discharged from the hospital whilst neutropenic and had a suspected period of neutropenia of a minimum of 10 days. Selective culture for Legionella, P. aeruginosa, and NTM was performed. Patients who required hospital readmission were monitored for infection with the aforementioned pathogens over the following 3 months. NTM were cultured in 62 (95.4%) households in concentrations from 1 to 1,000 CFU/500 ml. The facultative pathogenic species Mycobacterium chelonae (58.5% of taps) and M. mucogenicum (38.5% of taps) were most frequently detected. Legionella spp. was cultured from six households (9.2%), including five households with L. pneumophila in concentrations from 25 to 2,500 CFU/500 ml. P. aeruginosa was found in seven households (10.8%) in concentrations from 5 to 2,500 CFU/500 ml. While clinical infection with Legionella spp. was not detected in any patients, infection with M. chelonae and P. aeruginosa occurred in one and seven patients, respectively. However, transmission from household water could not be confirmed. Although the risk of infection from household water-borne pathogens appears low, preventive measures may be considered on an individual basis in patients with long-term immunosuppression as well as in patients with long-term central-vascular catheterization.