A cluster of three extrapulmonary Mycobacterium abscessusinfections linked to well-maintained water-based heater-cooler devices

AbstractBackground:Various water-based heater-cooler devices (HCDs) have been implicated in nontuberculous mycobacteria outbreaks. Ongoing rigorous surveillance for healthcare-associated M. abscessus(HA-Mab) put in place following a prior institutional outbreak of M. abscessusalerted investigators to a cluster of 3 extrapulmonary M. abscessusinfections among patients who had undergone cardiothoracic surgery.Methods:Investigators convened a multidisciplinary team and launched a comprehensive investigation to identify potential sources of M. abscessusin the healthcare setting. Adherence to tap water avoidance protocols during patient care and HCD cleaning, disinfection, and maintenance practices were reviewed. Relevant environmental samples were obtained. Patient and environmental M. abscessusisolates were compared using multilocus-sequence typing and pulsed-field gel electrophoresis. Smoke testing was performed to evaluate the potential for aerosol generation and dispersion during HCD use. The entire HCD fleet was replaced to mitigate continued transmission.Results:Clinical presentations of case patients and epidemiologic data supported intraoperative acquisition. M. abscessuswas isolated from HCDs used on patients and molecular comparison with patient isolates demonstrated clonality. Smoke testing simulated aerosolization of M. abscessusfrom HCDs during device operation. Because the HCD fleet was replaced, no additional extrapulmonary HA-Mab infections due to the unique clone identified in this cluster have been detected.Conclusions:Despite adhering to HCD cleaning and disinfection strategies beyond manufacturer instructions for use, HCDs became colonized with and ultimately transmitted M. abscessusto 3 patients. Design modifications to better contain aerosols or filter exhaust during device operation are needed to prevent NTM transmission events from water-based HCDs.