Frequently asked questions

What is the issue?

Some heater-cooler units used in cardiac surgery were contaminated with a rare bacterium called Mycobacterium chimaera (or M. chimaera), and there is a small risk that exposure to these units in the operating theatre may lead to infections in exposed patients that can appear months to years after surgery.

M. chimaera infections in cardiac surgery patients associated with a particular heater-cooler unit type made by LivaNova (Sorin) were first recognised in Switzerland. These devices, which were widely used around the world including Australia, are thought to have been contaminated during manufacture.

Over 120 patients worldwide have been identified with M. chimaera infections after cardiac surgery, including 7 people in NSW who had open heart surgery at Prince of Wales Hospital in 2015.

Genetic testing of clinical samples strongly links all NSW cases to the worldwide outbreak.

What is Mycobacterium chimaera?

Mycobacterium chimaera (M. chimaera) is one of a group of bacteria called non-tuberculous Mycobacterium bacteria (NTM) that are commonly found in the environment, such as water and soil.

M. chimaera only very rarely causes infections in people. Infections tend to develop very slowly and in people who are more susceptible to infections because of other health conditions.

What are heater-cooler devices?

Heater-cooler devices are often used during cardiac surgery because circulating blood and organs must be maintained at specific temperatures.

How are heater-cooler devices associated with infection?

  • M. chimaera and other bacteria are able to grow in the water tank of heater-cooler units.
  • Although the water in the heater-cooler unit does not come into contact with the patient’s blood or body fluids, contaminated water droplets from the tank may transmit bacteria through the air and then find its way to the patient during the surgery.
  • All current 3T devices in NSW public hospitals are fitted with an approved aerosol collection device which removes exhaust from the machine when it is in use, further reducing the risk to patients.

Which open-heart surgery patients need to be aware of this risk?

Patients who had open-heart surgery at the following locations and in the time periods listed:

NSW public hospitals

  • Children's Hospital Westmead: January 2012 - August 2016
  • Prince of Wales Hospital: January 2012 - August 2016
  • St George Hospital: January 2012 - April 2018

NSW private hospitals

  • Sydney Children's Hospital (Randwick): January 2012 - August 2016
  • Newcastle Private Hospital: July 2014 - September 2016
  • Norwest Private Hospital: January 2012 - August 2016
  • Prince of Wales Private Hospital: January 2012 - August 2016
  • St George Private Hospital: January 2012 - January 2017
  • The Sydney Adventist Hospital (Wahroonga): 22 January 2015 - 18 June 2015
  • Westmead Private Hospital: June 2014 - August 2016

ACT hospitals

  • National Capital Private Hospital: November 2011 - August 2016
  • Canberra Hospital: July 2014 - November 2016

As this is an international problem, patients who had cardiac surgery in other states or territories, or overseas could also have been exposed.

Are certain groups of patients at higher risk of M. chimaera infection?

M. chimaera and other NTM bacteria may cause serious infections in very ill patients including patients with compromised immune systems, underlying lung disease, diabetes, or patients undergoing chemotherapy or certain invasive healthcare procedures, or receiving heart valve surgery.

What has been done in NSW to reduce the risk?

  • Sorin heater-cooler units susceptible to M. chimaera infection were used in the listed hospitals in NSW and some of these were shown to be contaminated with M. chimaera.
  • In NSW, public facilities have reviewed processes to minimise the risk of infection. All affected Sorin heater-cooler units in public hospitals have been replaced or removed from service.
  • All heater-cooler devices in public hospital have testing for Mycobacteria performed every 3 months.
  • All Sorin heater-cooler devices in public hospitals have been retro-fitted with an aerosol collection device.

What are the symptoms of M. chimaera infections?

  • M. chimaera infections are very slow-growing. Because of this it can take from several months to many years for an infection to develop. To date, the longest time after surgery for an infection to be identified is 12 years.
  • The most common symptoms reported by patients with this infection following open heart surgery are persistent fevers, increasing or unusual shortness of breath, and unexplained weight loss.

Other signs of a possible M. chimaera infection may include:

  • fatigue
  • persistent cough or cough with blood
  • night sweats
  • muscle pain
  • abdominal pain
  • nausea
  • redness, heat, or pus at the surgical site
  • joint pain
  • vomiting.

What should I do if I am experiencing symptoms?

Contact your local doctor if you are experiencing symptoms and inform them that you had open-heart surgery.

Should I be tested even if I don’t have symptoms?

No, there is no test to show if people who are well are at risk of developing the infection in the future.

How is it treated?

M. chimaera infections can be treated with combinations of specific antibiotics. Some patients who become infected may need prolonged treatment (from months to years).

Additionally, although rare, some heart valve patients who develop M. chimaera infections after having cardiac surgery may require additional surgery. If untreated, M. chimaera infection could be fatal.

Can I become infected through contact with someone who is infected with M. chimaera?

No, M. chimaera infections are not contagious. They do not spread from person-to-person.

What should I discuss with my doctor prior to open-chest surgery?

Always discuss the benefits and risks of your surgical procedure with your doctor.

For most patients, the benefit of undergoing a cardiac procedure recommended by their doctor far outweighs the risk of infection. Ask your doctor what to expect following your procedure and when to seek medical attention.

Further information

Current as at: Wednesday 8 June 2022
Contact page owner: Communicable Diseases