EOC 75 - Routine Maintenance Treatment of Hospital Water Systems with Monochloramine Effectively Controls Legionella Growth

Background: Legionella pneumophilia is a bacterium that can cause serious lung infections. Exposures can occur from ill-managed man-made water systems or heating, ventilation, and air conditioning systems. Legionella is a pathogen of concern in healthcare systems due to pervasive aged plumbing infrastructure, and dependence on the municipality’s water treatment protocols. Identification of hospital-associated infections (HAIs) with Legionella is of significant concern to both the healthcare facility and the state public health department. Therefore, when a Food and Nutrition employee of a 500-bed hospital presented to the Emergency Department with respiratory symptoms and a positive Legionella pneumophilia Serotype 1 antigen result, an investigation was initiated to determine if this was an HAI.

Methods: A focused Water Management team was formed. Team members included a third-party water management vendor, Infection Prevention, Environmental Services, Hospital Leadership, and Facilities. Baseline environmental water sampling for Legionella was performed. A monochloramine injection system was installed, and the water system was treated for 30 consecutive days. Due to subsequent actionable levels (>1 Colony Forming Unit/milliliter), several variations of monochloramine treatment protocols were performed. Continued detection of actionable levels led to the development of a schedule to proactively administer monochloramine for 5 consecutive days per month.

Results: Baseline environmental water samples from the kitchen where the employee worked were above the actionable level for Legionella. After a 30-day cycle of monochloramine treatment, actionable levels were detected at 60 days. After implementing the routine treatment schedule of 5 consecutive days each month, environmental water cultures for Legionella have remained below the actionable level for the period of January 2023 through November 2023.

Conclusions: Legionella can persist in the healthcare setting despite targeted treatment. Monthly maintenance treatment of the hospital water system with monochloramine for 5 days has been successful in keeping Legionella growth below actionable levels.