A recent study published in the Annals of Internal Medicine examined an incident at a New England hospital in which four cardiac surgery patients in one hospital developed Mycobacterium abscessus infections, a multidrug-resistant nontuberculous mycobacteria. 

The patients who contracted the infections were admitted at different times and stayed in different rooms. They were, however, placed on the same floor with a shared water supply. Initial findings included the discovery of heavy mycobacterial growth in ice and water machines on the cluster unit but none in the hospital’s other inpatient towers.

The mycobacteria were most likely introduced into the hospital’s water system via the local water supply. 

“Mycobacterium abscessus is commonly found in municipal water and poses no threat to healthy individuals,” says Michael Klompas, M.D., MPH, lead author of the study. “However, they can cause infections in highly immunocompromised patients.”

The water supplying the unit’s ice and water machines passed through a commercial water purifier installed to improve water palatability, but that inadvertently removed chlorine. The equipment was being cleaned as per the manufacturer’s instructions, but inspection of the internal components of the machines found large amounts of biofilm.

Each hospital should have a comprehensive infection control program that includes measures taken by all front-line providers and the hospital, Klompas says. 

After finding the source of the infections, the hospital in this study overhauled service protocols for the entire facility, which included doubling the manufacturer’s recommendations around maintenance and replacement from twice yearly to quarterly.

High-risk patients were switched to sterile and distilled water, and the commercial purification system was decommissioned. Technicians servicing ice and water machines throughout the entire hospital were trained on best practices to avoid inadvertent contamination, and staff protocols around environmental services were revised to include daily cleaning of ice and water machine drip trays.

A centralized audit system was created to monitor the quality and frequency of preventive maintenance and daily cleaning, and high-efficiency particulate filters were installed in the water lines. The hospital’s water management plan was revised to codify these system-level changes, and water surveillance audits were expanded to include cultures for mycobacteria.

The original, well-intentioned effort demonstrated the risk of unintended consequences for especially vulnerable patients. 

The authors say strict adherence to recommended cleaning and maintenance protocols is imperative in care environments, and the introduction of outside systems that interact with existing internal mechanics make review and creation of new best practices around cleaning processes and protocols crucial to ongoing patient safety.