Invasive Nontuberculous Mycobacterial Infections among Cardiothoracic Surgical Patients Exposed to Heater–Cooler Devices1

Abstract

Invasive nontuberculous mycobacteria (NTM) infections may result from a previously unrecognized source of transmission, heater–cooler devices (HCDs) used during cardiac surgery. In July 2015, the Pennsylvania Department of Health notified the Centers for Disease Control and Prevention (CDC) about a cluster of NTM infections among cardiothoracic surgical patients at 1 hospital. We conducted a case–control study to identify exposures causing infection, examining 11 case-patients and 48 control-patients. Eight (73%) case-patients had a clinical specimen identified as Mycobacterium avium complex (MAC). HCD exposure was associated with increased odds of invasive NTM infection; laboratory testing identified patient isolates and HCD samples as closely related strains of M. chimaera, a MAC species. This investigation confirmed a large US outbreak of invasive MAC infections in a previously unaffected patient population and suggested transmission occurred by aerosolization from HCDs. Recommendations have been issued for enhanced surveillance to identify potential infections associated with HCDs and measures to mitigate transmission risk.

Infections and Outbreaks of Nontuberculous Mycobacteria in Hospital Settings

“…In addition, the organism’s propensity towards biofilm formation favors disease outbreaks [44]. In one instance, when a previously utilized HCD was dismantled for investigation, the biofilm was observed on surfaces in contact with the internal water reservoir [45]. This finding highlights the difficulty in achieving eradication of NTM in these settings [33].…”

Mycobacterium chimaera infections in post–operative patients exposed to heater–cooler devices: An overview

“…Patients undergoing cardiac surgery involving cardiopulmonary bypass where body temperature is regulated by HCDs are at risk of exposure and infection (8). Patients undergoing cardiopulmonary bypass for over two hours had higher odds of NTM infection (odds ratio: 16.5; 95% CI: 3.2-84) (8).…”

“…Patients undergoing cardiac surgery involving cardiopulmonary bypass where body temperature is regulated by HCDs are at risk of exposure and infection (8). Patients undergoing cardiopulmonary bypass for over two hours had higher odds of NTM infection (odds ratio: 16.5; 95% CI: 3.2-84) (8). In hospitals where at least one HCD-associated M. chimaera infection was identified, the risk of a patient getting an infection was approximately 0.1-1% (11,30,31).…”

“…Several types of microorganisms have been isolated from contaminated HCDs, including nontuberculous mycobacteria (NTM), which are ubiquitous in soil and water and have been linked to health care-associated infections (6)(7)(8)(9). Investigations of NTM infection clusters following cardiac surgery detected Mycobacterium chimaera as the causative microorganism.…”

“…Transmission was associated with a single model of HCD manufactured by Sorin (now LivaNova) (3,13). Cultures from HCD water tanks, water circuits and air samples taken while HCDs were in use have grown M. chimaera (5,8,9,11).…”