Published: 1 March 2018

Mycobacterial Infections after Cardiac Surgery Using Heater-Cooler Devices

Prescriber Update 39(1): 10
March 2018

Key Messages

  • Cases of non-tuberculous mycobacterial infection have been identified in patients who have undergone cardiac surgery using heater-cooler devices.
  • These infections can manifest many months or years after surgery.
  • Consider non-tuberculous mycobacteria in patients who present with symptoms of an infection, have negative conventional cultures, do not respond to antibiotic treatment and have undergone surgery where heater-cooler devices have been used.
  • Patients with these infections have presented with fatigue, fever, pain, redness, heat or pus at the surgical site, muscle pain, joint pain, night sweats, weight loss, abdominal pain, nausea or vomiting.
  • Medical practitioners with patients who have undergone surgery using affected heater cooler devices have been contacted.

Heater-cooler devices are used during cardiac surgery to maintain the patient’s temperature. Following reports of unusual infections in patients who had undergone cardiac surgery, investigations identified a problem with contamination of heater-cooler devices. Bacterial contamination of the water within the device can result in transmission of bacteria by aerosol from the device’s exhaust vent into the operating theatre. The type of bacteria involved in the infections were non-tuberculous mycobacteria.

Non-tuberculous mycobacteria include a number of different bacterial species, many of which are widespread in nature and can be found in water, including tap water. They are not usually a major cause of infection in the community. However, in rare cases they may cause infection in very ill or immune-compromised patients, or in situations where prosthetic material is implanted.

The organism is slow-growing so may present as infection months or even years after exposure.

Mycobacterial infection should be suspected in patients who have had cardiac surgery who present with any of the following symptoms: fatigue, fever, pain (including muscle or joint pain), redness, heat or pus at the surgical site, night sweats, weight loss, abdominal pain, nausea or vomiting. Cultures will be negative and the patient will not respond to conventional antibiotic treatment.

The exact number of cases worldwide is unclear, but the risk to patients is thought to be very low (roughly 1 in every 5000 procedures or 0.02%). However, these infections can be serious if they are not identified and treated. Due to the slow onset of symptoms, there is the potential for patients to present with these infections in the community.

To date, one case of infection attributable to non-tuberculous mycobacteria has been detected in New Zealand. Approximately 120 such cases have been identified worldwide. The New Zealand case was identified in 2015 and the patient was treated successfully.

Hospitals that use heater-cooler devices have been advised to consult with their infection prevention and control services to ensure that the decontamination and disinfection of these devices is performed according to the manufacturer’s instructions.

The Ministry of Health has asked District Health Boards and private providers to notify patients who underwent surgery at their centre during which cardiac prosthetic material was inserted and a heater-cooler device was used after 1 January 2013.

All adverse events relating to medical devices should be reported to Medsafe. The reporting forms are available on the Medsafe website ( and should be emailed to

Further information about heater-cooler devices used during cardiac surgery is published on the Medsafe website (