 despite adhering to cleaning and disinfection strategies meeting or exceeding manufacturers instructions for use various water based heater cooler devices have been implicated in nontuberculous mycobacteria ntm outbreaks ongoing rigorous surveillance for healthcare associated ntm alerted investigators to a cluster of three extrapulmonary m abscessus infections among patients who had undergone cardiothoracic surgery this outbreak investigation highlighted the need for additional heater cooler device design modifications to better contain aerosols or filter exhaust during device operation to prevent ntm transmission 