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Contaminated heater-cooler units facilitate invasive nontuberculous mycobacteria infection
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Contaminated heater-cooler units employed during cardiopulmonary bypass procedures appear to have facilitated a cluster of invasive nontuberculous mycobacteria infections among cardiothoracic surgery patients, according to recently presented data.
“Our investigation established an association between serious infections of a slow-growing bacteria and open-heart surgery involving heater-cooler units — temperature-regulating devices used during cardiac surgeries requiring cardiopulmonary bypass,” Meghan Lyman, MD, epidemic intelligence service officer at the CDC, told Infectious Disease News. “Microbiology testing suggested that patients became infected during open-heart surgery because the device caused aerosolization of the bacteria.”
Meghan Lyman
After receiving notification of several nontuberculous mycobacteria (NTM) infections in July 2015, Lyman and colleagues conducted a case-control study among patients of the affected hospital in Pennsylvania. To identify potential risk factors of infection, those with a NTM-positive culture between 2010 and 2015 obtained from a sterile body site 30 days to 3.5 years after cardiothoracic surgery were compared with controls with no NTM-positive cultures after the procedure. In addition, the researchers investigated hospital infection control procedures and analyzed clinical and environmental samples.
Examination of 10 cases and 48 controls revealed that patients who underwent major cardiac surgery involving cardiopulmonary bypass and required body temperature regulation with a heater-cooler unit were at increased risk for NTM infection (OR = 5.6; 95% CI, 1.1-29.2). This risk was further increased among those whose exposure to bypass exceeded 2 hours (OR = 16.5; 95% CI, 3.2-84). Pulsed-field gel electrophoresis testing of three available case-patient isolates produced closely related Mycobacterium chimaera patterns, which were corroborated by water and air samples taken when heater-cooler units were running in a simulated environment.
According to Lyman and colleagues, these findings are the first in the U.S. to implicate heater-cooler units in the development of invasive NTM infections among cardiothoracic surgery patients. The CDC has since released interim practical guidance advising facilities to remove contaminated heater-coolers from operating rooms and ensure that those in service are well maintained.
“CDC is working to increase awareness about these device-related infections among patients and clinical providers to improve diagnosis and treatment and is also working with the FDA on device design issues to reduce the risk of transmission,” Lyman said. – by Dave Muoio
References:
CDC. Non-tuberculous Mycobacterium (NTM) Infections and Heater-Cooler Devices Interim Practical Guidance: Updated October 27, 2015. http://www.cdc.gov/HAI/pdfs/outbreaks/CDC-Notice-Heater-Cooler-Units-final-clean.pdf. Retrieved May 5, 2016.
Lyman M, et al. Invasive nontuberculous mycobacteria infections among cardiothoracic surgery patients — hospital A, Pennsylvania, 2010-2015. Presented at: Epidemic Intelligence Service Conference: May 2-5, 2016; Atlanta.
Disclosure: The researchers report no relevant financial disclosures.