Mycobacterium chimaera and heater-cooler devices

​​​​Some heater-cooler devices (HCDs) used in open-heart cardiac surgery have been found to be contaminated with a rare bacterium called Mycobacterium chimaera (or M. chimaera). Exposure of patients to these HCDs during cardiac surgery may lead to infections that can appear months to years after surgery.

In 2015, a cluster of cardiac surgery patients with M. chimaera were reported from Switzerland (ref). Related cases were subsequently reported from Germany, the Netherlands, the United Kingdom, the United States and Australia.

M. chimaera infections in cardiac surgery patients are associated with exposure to a particular HCD - the Stöckert 3T made by Sorin (now known as LivaNova ). These devices, which are widely used around the world, are thought to have been contaminated during manufacture.

M. chimaera are slow-growing bacteria and infections have been diagnosed from months to up to twelve years after open-heart surgery involving the implicated HCDs.

Risk mitigation​​​​

The Therapeutic Good s Administration (TGA) has provided alerts on this issue and the Australian Commission on Safety and Quality in Health Care (ACSQHC) also issued updated National Infection Control Guidance relating to heater-cooler devices in March 2020.

The overall risk to individual patients is thought to be very low. The risk is higher for patients who had prosthetic implants (such as heart valve replacements) during their cardiac surgery compared to those who did not receive implants.

In August 2016, NSW Health undertook the following risk mitigation strategies:

• replaced all Sorin 3T HDCs at NSW public hospitals
• conducted a look-back at Local Health Districts that had confirmed device contamination
• issued alerts to the community and doctors
• circulated new national control guidelines for HCDs that involved strategies such as regular cleaning and testing of the devices.

Eight NSW residents who had open heart surgery at in 2015 have been confirmed to have developed M. chimaera infections. The most recent case was identified in 2022. Clinical presentations included endocarditis, infected sternal wound, and discitis and some of these people have died.

Information on cases in other States and Territories is available via the TGA Infections associated with heater-cooler devices alert site .

Unfortunately, there is no test to tell if a patient has been exposed to the bacteria before symptoms of the infection develop.​