Legionella Colonization Prevention in Ice Machines

Legionnaires disease is a serious, sometimes lethal pneumonia caused by Legionella. US cases increased 217%, from 2000 to 2009. Legionella can multiply at 20–45°C but is dormant at colder temperatures. Ice machines are typically fed by cold water but water temperature can increase due to proximity of the generator allowing Legionella to amplify. Current ice machine maintenance guidelines include cleaning and descaling but there are no recommendations to prevent Legionella colonization. After identifying ice machines as a source of Legionella infection, filters were added to routine maintenance and evaluated. This method was labor intensive and compliance was challenging so continuous sanitization with monochloramine was implemented. Efficacy was evaluated by culturing ice weekly, capturing all machines quarterly. The objective of this study was to compare the effectiveness of these Legionella prevention interventions. Three Time periods (TP) were evaluated: · TP1 – Pre intervention (11/29/2010–01/09/2014) o Semi-annual cleaning and descaling · TP2–Point-of-use (POU) water filters (01/10/2014–09/30/2015) o Quarterly bleach sanitization and descaling o Pall-Aquasafe™ 0.2u Disposable Water Filters § Validated for up to 31 day use. · TP 3 - Monochloromine 10/01/2015–04/27/2017) o Semi-annual bleach sanitization and descaling Monochloramine treated incoming water During TP-2 the positive ice machines were attributed to a failure in manual process, either not adequate sanitation of the ice machine or the 0.2u filter was not changed within 31 days. · Comparing TP-1 to TP-2, the p-value is 0.1539. · Comparing TP-1 to TP-3, the p-value is <0.0001 · Current ice machine cleaning and descaling guidelines were associated with the highest colonization rates and could lead to increased Legionella hospital acquired infections POU filters had a lower rate of colonization but changing all filters within 31 days is challenging. Manual interventions have the ability to work, but need to be strictly followed and maintained.· Continuous disinfection with Monochloramine was most effective as preventing Legionella colonization and was easiest to maintain All authors: No reported disclosures.