Infections associated with heater-cooler devices

In 2019, we completed a product safety review into all heater-cooler devices supplied in Australia. 

The review of the Heater Cooler Devices was based upon reports of Mycobacterium chimera (a type of non-tuberculous mycobacterium) infections which have been associated with the use of heater-cooler devices. 

The devices are characterised as containing water reservoirs that provide temperature-controlled water for the operation of the device and are used in cardiac bypass surgery and extracorporeal membrane oxygenation (ECMO). 

Information about this review can be found in the table below.

Heater-cooler devices are used within operating theatres and intensive care units, to control the temperature of blood, during procedures where heating or cooling of blood is required. 

The devices contain water tanks that provide temperature-controlled water for the operation of the device. 

This water is not intended to come in contact with the patient or their blood.

The TGA previously published advice (see below) regarding the potential for water within heater-cooler units to become contaminated with bacteria, in particular, non-tuberculous mycobacterium (NTM). 

There is evidence to suggest that patients are infected when bacteria in the device's water tank becomes airborne in the operating room during surgery.

During the last quarter of 2025, we have received an increased number of reports of Mycobacterium contamination in heater-cooler units. 

These reports involve two common species, Mycobacterium gordonae and Mycobacterium chimaera. 

No patient infections have been reported. However, this highlights the importance of device users or contracted service providers, to adhere to the Instructions for Use (IFU), particularly regarding regular cleaning and decontamination, including whilst the devices are in storage.

We remind users to review the information in Risk mitigation for all heater-cooler units below, which outlines key steps to help prevent contamination. 

Whether the cleaning and maintenance activities are performed in-house, or outsourced to third-party providers, it is important to ensure that these activities are carried out in strict accordance with the relevant Instructions for Use (IFU) for the device.

We continue to monitor this situation and strongly encourages reports of contamination to be submitted. 

When submitting a Device Incident Report (DIR) for Mycobacterium contamination of a heater-cooler device, providing comprehensive and relevant information enables the TGA to conduct timely risk assessments and determine appropriate action. 

For further guidance on what critical information may be included in a Device Incident Report (DIR), see Reporting problems.

TGA recommendations

The TGA has the following recommendations to reduce the risk of infection to patients when using water-based heater-cooler devices:

• In appropriately selected patients, the benefits of temperature control during open-chest cardiothoracic procedures generally outweighs the risk of infection transmission associated with water-based heater-cooler devices.
• Strictly adhere to the clearing and disinfection instructions provided in the manufacturer’s heater-cooler device labelling. Ensure the most current version of the manufacturer's instructions for use are readily available for staff who use these devices.
• Do not use tap water to rinse, fill, refill or top-off heater-cooler water tanks as this may introduce NTM organisms. Use only sterile water or water that has been passed through a filter of less than or equal to 0.22 microns. When making ice needed for use in the heater-cooler, use only sterile water or water that has been passed through a filter of less than or equal to 0.22 microns. Deionized water and reverse osmosis-treated water are not recommended because they may promote corrosion of the metal components of the system.
• Always direct and/or channel the heater-cooler device's exhaust vent(s) away from the surgical/sterile fields and toward an operating room exhaust vent during device set-up and surgical procedures as well as after use to mitigate the risk of aerosolized heater-cooler tank water reaching the sterile field.
• Establish regular cleaning, disinfection and maintenance schedules for heater-cooler devices according to the manufacturer's instructions to minimize the risk of device contamination and patient infection.
  • Be aware that not following the heater-cooler manufacturer's cleaning instructions (frequency of cleaning and disinfection, strength of disinfectants used, and so forth) can damage the device.
  • Follow a comprehensive quality control program for periodic maintenance, cleaning, and disinfection of heater-cooler devices, including while a device is in long-term storage. This may include written procedures for monitoring adherence to the program and documenting set up, cleaning, and disinfection processes before and after use.
  • Use new accessories, tubing, and connectors to prevent possible recontamination when using a different heater-cooler device.
  • Be aware that device contamination may also occur from other sources such as environmental contamination or device contact with contaminated accessories.
  • Clean, disinfect and exchange heater-cooler and accessory tubing as per the manufacturer recommendations
  • Follow manufacturer instructions for storage of heater-cooler devices and accessories when not in use, which may include removing all water from the device and tubing.
• Immediately remove from service heater-cooler devices that show discoloration or cloudiness in the fluid lines/circuits. This may indicate contamination. Consult your hospital infection control officials to perform the appropriate follow up measures and report events of device contamination to the manufacturer.
• Consider performing environmental, air, and water sampling and monitoring if heater-cooler contamination is suspected. Environmental monitoring requires specialized expertise and equipment to collect and process samples, which may not be feasible in all facilities.
• Patients suspected of an infection associated with heater-cooler devices or exposed to a contaminated heater-cooler device should be notified and evaluated. Health care facilities should follow their internal procedures for notifying and evaluating patients.
• Report any issues with heater-cooler devices to the TGA, including if you suspect heater-cooler devices have led to patient infections or any type of contaminating of a heater-cooler device. See Reporting problems.

Information for health professionals and facilities

Consistent with the national guidance issued by the ACSQHC, we recommend baseline testing, then follow-up testing in accordance with the manufacturer's instructions. 

Where information from the manufacturer is not available and the initial sample from the HCD is negative, then follow-up testing should occur at least every three months. 

This testing cycle should be maintained until further information about this situation becomes available.¹ 

The manufacturer's instructions will provide guidance on the type and frequency of testing with common elements being:

• Two microbiological methods are being recommended by some manufacturers - cultures of heterotropic plate counts (HPC) and mycobacterial cultures.
• Environmental samples should be submitted to a suitable laboratory identified in consultation with the jurisdictional public health laboratory and tested using validated culture-based methods.
• Mycobacterial cultures of environmental samples requires specialised expertise, which may not be available in all facilities.
• Hospital protocols should account for the potential delay in receiving results from mycobacterial cultures, a clear result may take 6-8 weeks or longer.

If there are cases of legionellosis in patients, particularly cardiac surgery patients, then health professionals should consider the heater-cooler device as a possible source. 

Routine patient testing for legionellosis is not recommended at this time.

Addressing Mycobacterium chimaera infections

Reported infections overseas include surgical site infection, endocarditis, prosthetic valve infection, para-valvular abscess, graft infection and myocarditis. 

While initial case reports described mostly fatal infections, early recognition of Mycobacterium chimaera as the cause appears to result in better patient outcomes. 

Based on the available data, the case fatality rate is about 50%.

Some patients have presented with non-cardiac disease: granulomas, osteoarthritis, cholestatic hepatitis, nephritis, splenomegaly, or ocular disease.

Patients undergoing heart valve surgery, particularly with prosthetic implants, are considered to be at highest risk.

Based on the currently available data, the risk of infection from contaminated aerosols from heater-cooler devices, in general, is thought to be very low.

Heater-cooler devices are important in patient care and, in appropriately selected patients, the benefits of temperature control necessary during open chest cardiothoracic procedures outweigh the risk of infection transmission associated with using these devices.

TGA product safety review

The TGA safety review investigated all heater-cooler devices included in the Australian Register of Therapeutic Goods (ARTG) that were characterised as containing water reservoirs that provide temperature-controlled water for the operation of the device and are used in cardiac procedures: bypass and ECMO.

There were more than 100 patients worldwide identified as having been infected with one species of NTM, Mycobacterium chimaera, following cardiac surgery. 

These cases of infection with Mycobacterium chimaera have been identified between three months and five years postoperatively.

An article published in The Lancet on 12 July 2017 provides further information about research that is being undertaken to determine the source of contamination and infection.

The risk of Mycobacterium chimaera infection in patients undergoing open-heart surgery has been estimated as 0.4-16 per 10,000 patient-years. 

Given a background risk of 1.2% for surgical site infection in the first year after cardiac valve operations, and a cumulative 5-year incidence of prosthetic valve endocarditis of 3.2-5.7%, the risk of infection by Mycobacterium chimaera is low by comparison.

The table below lists all of the medical devices included in the review that have been on the ARTG and are known to have been supplied in Australia. 

Some devices may no longer be used or are being used as back-up devices. This table is updated when information changes.

Contamination found in devices

There was a report in early 2019 of a new isolate of Mycobacterium chimaera being identified in a heater-cooler unit that had previously tested negative for contamination in 2017 and early 2018. 

The report was considered by a collaborative group of Australian laboratories, the Public Health Laboratory Network, at their meeting on 29 May 2018. 

The heater-cooler unit involved was taken out of service and notification letters were sent to potentially affected patients advising them of the follow-up required. 

In this case, it is believed the most likely cause was the gradual development of a biofilm in the affected heater-cooler unit, which would previously have been below the limit of detection and so was not identifiable earlier. 

A working group to review the testing guidelines has been formed and will meet again in the near future.

The TGA has received reports for Mycobacterium chimaera contamination of eleven Stöckert 3T Heater-Cooler System (3T) devices manufactured after September 2014. 

The investigation into these recent reports did not identify a root cause. However, it is possible for devices to be contaminated via being stored with other contaminated devices and the use of hoses and connectors that have been used on contaminated heater-cooler units as well as the slow growth of biofilm. 

It is recommended that hoses and connectors are not swapped between heater-cooler units. 

Additionally, Liva Nova recommends that health facilities:

• Ensure all fill and emptying tasks be performed outside the operating room.
• Do not perform the external circuit emptying steps until the patient has been discharged from the operating room environment to eliminate the potential of exposure to aerosol.

The TGA had previously received reports for Mycobacterium chimaera contamination of Stöckert 3T devices manufactured before September 2014, infections have to date been associated with Stöckert 3T heater cooler devices manufactured prior to September 2014.

There have been three reports to date for NTM contamination in Maquet HCU 20 devices. 

Two of the devices tested positive for Mycobacterium gordonae, one of these devices has been disinfected. 

Another device has tested positive for Mycobacterium chimaera; this device has been decommissioned.

There have been three reports for NTM contamination in Maquet HU 35 devices. One of these devices tested positive for Mycobacterium chelonae, this device has been disinfected. 

Another device has tested positive for Mycobacterium abscessus and chelonae complex; this device has been taken out of service until it can be disinfected. 

Another device has tested positive for Mycobacterium chimaera; this device has been disinfected.

Unused units: There have been five reports to date of NTM contamination in unused ParaTherm Heater/Cooler units. In three of these cases Mycobacterium chimaera has been confirmed. In the other two cases the species of NTM was not identified.

ParaTherm Heater/Cooler units are not indicated for use in open-heart surgery, the surgical setting that is believed to pose the greatest risk of NTM infection.

There have been no incidents reported to the manufacturer, Chalice Medical Ltd, of NTM patient infection associated with the use of the ParaTherm Heater/Cooler.

Infections associated with heater-cooler devices

Alert - updated advice for health professionals and facilities

28 October 2016

Consumers and health professionals are advised that the TGA has updated its information about mitigating the risk of Mycobacterium chimaera infections from heater-cooler devices. For more details see 'Information for health professionals and facilities' below.

Heater-cooler devices are used within operating theatres to control the temperature of blood diverted to cardio-pulmonary bypass machines. Heater-cooler devices contain water tanks that provide temperature-controlled water for the operation of the device. This water does not come in contact with the patient.

The TGA published advice about this issue in a web statement on 2 August and in the May edition of Medical Devices Safety Update.

The Australian Commission on Safety and Quality in Health Care (ACSQHC) issued New National Infection Control Guidance relating to heater-cooler devices in September.

More than 50 patients worldwide have been identified with >Mycobacterium chimaera infections after cardiac surgery. Cases of infection with Mycobacterium chimaera have been identified between three months and five years postoperatively. There is evidence to suggest that patients are infected when bacteria in the device's water bath becomes airborne.

There has been a single case report in Australia. The patient involved in this case is recovering.

Infection is a recognised consequence of all surgery and up to 3-5% of patients develop valve infections within the first 5 years after valve surgery. The risk for mycobacterial infection from contaminated aerosols from heater-cooler devices is considered to be very low compared with the overall risk of surgical and valve infection.

The US Food and Drug Administration issued a safety communication on 13 October in relation to contamination with Mycobacterium chimaera of one model of heater-cooler (Stöckert 3T Heater-Cooler System by LivaNova (Sorin)).

Based on the currently available data, and as determined by genomic sequencing of organisms, the Mycobacterium chimaera infections have been identified as a point source outbreak, with the heater-cooler units now believed to have been contaminated at the point of manufacture. 

The product affected is the Stöckert 3T Heater-Cooler System (3T) manufactured in Germany by LivaNova. 

The manufacturer implemented post-production/pre-shipping disinfection procedures on 18 August 2014 that have reduced the risk for units manufactured after September 2014.

Some sponsors of heater-cooler devices are undertaking recall actions in Australia (for example, updating the Instructions for Use regarding disinfection) to mitigate the risk of contamination. Recall actions are published in the System for Australian Recall Actions database.

TGA has received reports for Mycobacteria chimaera contamination of Stöckert 3T Heater-Cooler System (3T) devices.

Testing of Stöckert 3T Heater-Cooler System (3T) devices by hospitals in Australia has identified that 25% of these devices have tested positive for the Mycobacterium chimaera organism or other organisms. All devices that tested positive were manufactured prior to September 2014.

The overall issue of microbial contamination of heater-cooler-units was also highlighted in the United States when the University of Washington Medical Center reported contamination of three heater-cooler devices with Legionella sp. bacteria in September 2016. Four patients were diagnosed with legionellosis (Legionnaires' disease) and two died. The source of the outbreak was linked to the hospital's water supply, as bacteria were also detected in an ice machine and two sinks in the hospital's cardiac unit. There have been no reports in Australia of heater-cooler devices being contaminated with Legionella sp. bacteria.

The TGA will continue to consult with an expert advisory panel regarding the issue of microbiological contamination of heater-cooler devices and to monitor the issue.

Information for users and patients

Based on the currently available data, and following the actions of the post-market review, the risk of patient infection from contaminated aerosols from heater-cooler devices, in general is expected to be very low.

If you, or somebody you provide care for, has undergone cardiac surgery in the previous 5 years, be aware of the possible signs and symptoms of Mycobacterium chimaera infection. These may include:

• fatigue
• fever
• pain
• redness, heat, or pus at the surgical site
• muscle pain
• joint pain
• night sweats
• weight loss
• abdominal pain
• nausea
• vomiting

If you, or somebody you provide care for, is experiencing any of the signs and symptoms above following cardiac surgery, contact your doctor as soon as possible.

Stratified risk mitigation for Stöckert 3T Heater-Cooler System (3T) devices

Risk mitigation advice for Stöckert 3T Heater-Cooler System (3T) devices manufactured before September 2014:

• Consider transitioning away from reliance on and the use of these devices (regardless of contamination status) for open-chest cardiac surgery until the manufacturer has implemented strategies for these devices to mitigate the risks of patient infection.
  • Use of these devices should be limited to emergent and/or life-threatening situations if no other heater cooler devices are available.
  • Follow the recommendations for all heater-cooler units (detailed below) to help mitigate the risks of patient infection.
  • Be aware that testing of heater-cooler devices to identify units contaminated with Mycobacterium chimaera presents technical challenges related to sample collection, the long culture time, and the possibility of false negative tests.

Risk mitigation for Stöckert 3T Heater-Cooler System (3T) devices manufactured after Sep 2014:

• Follow the recommendations for all heater-cooler units (detailed below) to help mitigate the risks of patient infection.

Risk mitigation for all heater-cooler units

• Strictly adhere to the cleaning and disinfection instructions provided in the manufacturer's device labelling. Ensure you have the most current version of the manufacturers' Instructions for Use readily available to promote adherence.
• Do not use tap water to rinse, fill, refill or top-off water tanks since this may introduce non-tuberculous mycobacterium (NTM) organisms. Use only sterile water or water that has been passed through a filter of less than or equal to 0.22 microns.
• When making ice needed for patient cooling during surgical procedures use only sterile water or water that has been passed through a filter of less than or equal to 0.22 microns.
• Deionized water and sterile water created through reverse osmosis is not recommended because it may promote corrosion of the metal components of the system.
• Direct the heater-cooler's vent exhaust away from the surgical field to mitigate the risk of aerosolising heater-cooler tank water into the sterile field and exposing the patient.
• Establish regular cleaning, disinfection and maintenance schedules for heater-cooler devices according to the manufacturers' instructions to minimise the risk of bacterial growth and subsequent patient infection.
• Develop and follow a comprehensive quality control program for maintenance, cleaning, and disinfection of heater-cooler devices. Your program may include written procedures for monitoring adherence to the program and documenting set up, cleaning, and disinfection processes before and after use.
• Regularly check for and immediately remove from service heater-cooler devices and accessories that show discoloration of internal surfaces or cloudiness in the fluid lines/circuits, which may indicate bacterial growth.
• Consult your hospital infection control officials to perform the appropriate follow up measures and report events of device contamination to the manufacturer and to the TGA.
• Consider performing environmental (water) sampling of the water supply and monitoring if heater-cooler contamination is suspected. Environmental monitoring requires specialised expertise and equipment to collect and process samples, which may not be feasible in all facilities.
• Submit a report to the manufacturer and to the TGA, if you suspect heater-cooler devices have been associated with patient infections.

Patient 'look backs' following exposure

Currently, there are no evidence-based guidelines available on the follow-up of patients who have been exposed to a contaminated device.

Screening asymptomatic patients for NTM is currently not indicated. At this stage, the TGA recommends liaising with the medical director of the health facility and state/territory public health units to determine the most appropriate protocol in your jurisdiction.

Reporting problems

Consumers and health professionals are encouraged to report problems with medical devices. 

Your report will contribute to the TGA's monitoring of these products. For more information see the TGA Incident Reporting and Investigation Scheme (IRIS). 

When submitting a report for a heater-cooler device, some specific information that may assist the TGA in assessing these reports are:

1. Purchase date and serial number/s of the device/s
2. Documentation of contamination results (e.g. pathology reports)
3. Identified Mycobacterium species name/s
4. Documentation demonstrating cleaning and decontamination history (e.g. previous 6 months) of the device/s including all required cleaning and disinfection as per the Instructions of Use
5. Testing dates and results (including details of any repeat tests)
6. Parties responsible for conducting regular maintenance, disinfection and cleaning of devices (if this is conducted by a third-party, advise details)
7. Whether the devices were in clinical use prior to positive water sample testing
8. Any patient harms observed
9. Actions taken since detection (e.g. sponsor notification and timing, further cleaning methods and outcomes) and current device status (e.g. in use or in storage)

The TGA cannot give advice about an individual's medical condition. 

You are strongly encouraged to talk with a health professional if you are concerned about a possible adverse event associated with a medical device.