Do We Need To Modify Our Approach to Legionella Prevention in the Setting of Natural Disasters?

ISSUE: Legionella is an important cause of nosocomial pneumonia, and is associated with high morbidity and mortality in oncology patients. Prior to the opening of a new cancer center (CC) building at our institution in 2000, chlorine dioxide (CD) disinfection of the water system was implemented to be in compliance with CDC and state health department guidelines for water treatment. The CC houses solid tumor, leukemia, and lymphoma patients, as well as bone marrow transplant recipients. Routine surveillance cultures (SCs) of the water (usually 27 sites) is performed quarterly. Although initially SC revealed growth of Legionella and gram-negative species in the water, growth decreased significantly during the first 18 months of implementation of the CD system. No Legionella pneumophila (LP) had ever been isolated. CD levels could be maintained below 0.4ppm (lower than EPA recommendations) without significant growth. After an unusually large amount of rainfall this past spring and summer, followed by flooding and disruption of the cityʹs water supply associated with Hurricane Isabel, scheduled SCs revealed LP type 1 in 9 of 12 sites. LP also grew in the city water. PROJECT: The CC was placed on water restrictions to protect the vulnerable patient population. Patients were given bottled water to drink and bathed with prepackaged clothes; they were not allowed to use the tap water. The water was treated with higher concentrations of CD to supplement the baseline in the system. Water faucets were opened for 10 minutes each day to ensure that CD-treated water reached terminal sites. RESULTS: There were no clinical cases of Legionella identified before or after expanded CD treatments. Follow-up cultures after the first treatment grew LP in 7 of 14 sites. After two additional treatments, SCs revealed successful eradication of Legionella. Routine SCs remain negative for Legionella. LESSONS LEARNED: CD has proven to be an effective method of disinfecting a water system in a CC that houses high risk patients. Institutions should be aware of the potential for increased bioburden in water after heavy rainfall or hurricanes and should consider surveillance or “prophylactic” treatment to protect the water in healthcare systems.