Frequently asked questions

Updated: 11 August 2017

What is the issue?
What is Mycobacterium chimaera?
What are heater-cooler devices?
How are heater-cooler devices associated with infection?
Which open-heart surgery patients need to be aware of this risk?
Are certain groups of patients at higher risk of M. chimaera infection?
What has been done in NSW to reduce the risk?
What are the symptoms of M. chimaera infections?
What should I do if I am experiencing symptoms?
Should I be tested even if I don’t have symptoms?
How is it treated?
Can I become infected through contact with someone who is infected with M. chimaera?
What should I discuss with my doctor prior to open-chest surgery?
Further information

What is the issue?

There is a risk that heater-cooler units used in open-heart cardiac surgery may have been contaminated with a rare bacterium called Mycobacterium chimaera (or M. chimaera), and that exposure of patients to these units in the operating theatre may lead to infections that can appear months after the surgery.

Infection of cardiac surgery patients with M. chimaera associated with a particular heater-cooler unit type (made by Sorin) was first recognised in 2012 in Switzerland. These devices, which are widely used around the world including Australia, are thought to have been contaminated during manufacture up until September 2014.

At least 100 patients worldwide have been identified with M. chimaera infections after cardiac surgery, mostly in patients whose surgery included implants such as heart valves.

In December 2016, NSW Health contacted patients who may have been exposed to the M. chimaera infection from contaminated open-heart surgery equipment used in four affected NSW public hospitals. Since that time there have been four cases of M. chimaera infection reported in NSW, all in patients who underwent open-heart valve surgery at Prince of Wales Hospital in 2015.

What is Mycobacterium chimaera?

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

  • There is the potential for M. chimaera or other bacteria to grow in a water tank in the 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 (aerosolize) and then find its way to the patient during the surgery.

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

  • NSW Public Hospitals: Children’s Hospital Westmead, Prince of Wales, St George, Sydney Children’s (all Jan 2012 – Aug 2016)
  • NSW Private Hospitals: Newcastle Private (July 2014 – Sept 2016), Norwest Private (Jan 2012 – August 2016), Prince of Wales Private (Jan 2012 – August 2016), St George Private (Jan 2012 – Jan 2017), The Sydney Adventist Hospital, Wahroonga (between 22 January and 18 June 2015), Westmead Private (June 2014 – Dec 2016)
  • ACT: National Capital Private (Nov 2011-Aug 2016) and Canberra Hospital (Jul 2014 – Nov 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 may cause serious infections in very ill patients including patients with compromised immune systems, underlying lung disease, diabetes, or patients undergoing chemotherapy (cancer treatment).
  • Patients exposed to the bacteria during invasive healthcare procedures, such as heart valve replacement surgery, or also at higher risk of infection.

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 testing revealed that units in four hospitals showed evidence of M. chimaera contamination.
  • All contaminated heater-cooler units in the four affected hospitals were replaced and removed from service in August 2016.
  • Other facilities with these units have reviewed processes to minimise the risk of infection. All heater-cooler units have and are continuing to be cleaned as per the manufacturers’ instructions.
  • Updated guidance on routine microbiological testing of this equipment has also been issued by the Clinical Excellence Commission.

What are the symptoms of M. chimaera infections?

  • M. chimaera infections are slow-growing. Because of this it can take from several months to over a year for an infection to develop.
  • 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

Page Updated: Friday 11 August 2017