Reduction in Legionella pneumophila through Heat Flushing Followed by Continuous Supplemental Chlorination of Hospital Hot Water

Abstract

An increase in endemic rate of nosocomial Legionella pneumophila pneumonia prompted an investigation that revealed 16.2% (12/74) of patient care hot-water sites surveyed were culture-positive for L. pneumophila. No positive cultures were recovered from cooling towers, air intakes, or construction areas. Heat flushing of hospital hot-water outlets to temperatures greater than 60 degrees C for 30 min achieved a 66% reduction in positive Legionella cultures. After 4 1/2 months, different serotypes recurred in previously eradicated areas and there were new positive cultures. Continuous supplemental chlorination of the hot-water system (2 parts per million [ppm]) significantly reduced the number of culture-positive samples from 37.4% (43/115) to 7.0% (8/115) after 6 weeks (P less than .005). Of 30 sites surveyed 6 months after hot-water chlorination, 67% (20) were still culture-negative. Of those positive, 70% had less than or equal to 150 L. pneumophila/ml and 90% were from bathtubs. Adverse effects of chlorination on users and plumbing have not been seen. There have been no definite cases of nosocomial L. pneumophila in areas served by supplemental chlorine during the first 17 months of the chlorination project. Technology allowing tighter regulation of chlorine and use of silicates to control corrosion have made continuous hot-water chlorination a safe and effective option in Legionella control.

Nosocomial legionellosis outbreak over a three-year period: investigation and control

“…Infection via inhalation of aerosols is a usual route of transmission of legionellae from environmental reservoirs to susceptible patients [18]. Nosocomial legionellosis is generally observed in immunocompromised patients [2–5]; our patients were diabetic or received immunodepressive treatment. All of them but one had received inhalation therapy by aerosols (two cases) or oxygen therapy (three cases).…”

“…Among Legionella spp., Legionella pneumophila serogroup 1 is the most common agent found to be responsible for nosocomial infections [1,2]. Immunocompromised patients are particularly at risk for such infections, especially those undergoing intensive care, organ transplantation or corticosteroid therapy [3–5]. Susceptible patients are infected after inhalation of aerosols containing bacteria from contaminated hospital reservoirs, including potable water, cooling towers, faucets or respiratory therapy devices [1,5–10].…”

“…Immunocompromised patients are particularly at risk for such infections, especially those undergoing intensive care, organ transplantation or corticosteroid therapy [3–5]. Susceptible patients are infected after inhalation of aerosols containing bacteria from contaminated hospital reservoirs, including potable water, cooling towers, faucets or respiratory therapy devices [1,5–10]. However, Legionnaire's disease is often not considered in the differential diagnosis of nosocomial pneumonia, and instead cases are sometimes only identified through routine testing of clinical specimens.…”

Legionella—Every Infection Preventionist's Dream—Or Is It?

“…16,18 Pall filters were placed in the high-risk units for the first 2 weeks. 1,19,20 Beginning June 25, 2006, chlorine was periodically injected through temporary chlorine injectors-no approval from the Texas Center of Environmental Quality was necessary.…”

“…5,21 Ultraviolet radiation is a point of use disinfectant, but there are no distal, residual effects. 20,[24][25][26][27][28][29][30] Chlorine dioxide is an Environmental Protection Agency-approved biocide for potable water, is effective on cold water, is effective against biofilm, is less corrosive than chlorine, and is costly. 19,[24][25][26][27][28][29][30] Ionization works well on copper return loops but is not designed for use on cold water and is costly.…”