Consumers and health professionals are advised that a total of seven Australians have been confirmed with Mycobacterium chimaera infections following heart surgery involving heater-cooler devices. NSW Health has reported four Mycobacterium chimaera patient infections, Victoria has reported two and Queensland has one reported case. There has been one confirmed report of death related to the infection in NSW.
The TGA has been conducting a product safety review into all heater-cooler devices supplied in Australia.
The above confirmed cases of infection are associated with contaminated Stöckert Heater-Cooler 3T heater-cooler units that were manufactured before September 2014.
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 focus of the review is those heater-cooler devices intended to be used for cardiac bypass surgery and extracorporeal membrane oxygenation (ECMO).
The TGA previously published advice 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.
The latest recall for product correction by LivaNova, the Sponsor of the Stöckert 3T devices in Australia, was published on the TGA Recall actions website on 27 October 2017. The correction was to install a modification that reduces the risk of potential patient infection by preventing dispersion of contaminated aerosols in the operating room. This correction was implemented by onsite modification of units currently in hospital use. The servicing was undertaken in the field by LivaNova service personnel or a local agent. Although the potential for infection is less likely when the 3T device’s water system is maintained according to the current Instructions for Use (IFU), the disinfectant required to undertake the maintenance was not included in the appropriate category of the Australian Register of Therapeutic Goods (ARTG). Therefore, the TGA suspended the supply of new 3T devices until the disinfectant could be suitably accessed to ensure adequate maintenance; and the instructions for use were updated to reflect the disinfectant use and the physical changes to the device. The disinfectant was included in the ARTG on 9 August 2018. The suspension of the 3T device from the ARTG entry did not preclude LivaNova from undertaking the modifications to existing 3T devices. Additionally, any remaining 1T devices were replaced with 3T devices as the 1T devices were unable to be modified to prevent aerosol dispersion.
There are more than 100 patients worldwide identified as being 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 TGA safety review will investigate all heater-cooler devices included in the Australian Register of Therapeutic Goods (ARTG) that are 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.
Contamination found in devices
There was a report earlier this year 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 eight 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, as reported in our previous web statement below. All patient 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.
(Source: Therapeutic Goods Administration, The Lancet)