Cardiac surgery and Mycobacterium chimaera infection

Recent investigations by Public Health England (PHE), the Medicines and Healthcare Regulatory Authority (MHRA) and NHS England have suggested that an essential device used to heat and cool the blood during some types of heart surgery has been linked to a rare bacterial infection caused by Mycobacterium chimaera.

We currently have no known cases, this includes patients operated on at Southampton General Hospital and Spire Southampton. We routinely monitor our heater-cooler devices to look for contamination and ensure that they are safe to use in accordance with PHE and manufacturers guidance.


The risk of acquiring this infection following cardiac surgery is very low and has been estimated to be less than 1 case per 100,000 coronary artery bypass graft procedures. The highest risk group is patients who have undergone valve replacement or repair, whose risk is currently estimated at 1 case per 5,000 procedures. Risk of infection is also low in non-valve-related congenital heart disease repair.


Symptoms of infection with Mycobacterium chimaera have many of the same features of other illnesses and can be slow to develop and be difficult to diagnose. It requires specific treatment.

Symptoms to be aware of include:

  • unexplained fevers
  • unexplained weight loss
  • increasing shortness of breath
  • waking up with bed sheets showing signs of sweating (night sweats)
  • joint or muscular pain
  • nausea, vomiting or abdominal pain
  • abnormal levels of tiredness / fatigue
  • pain, redness, heat and / or pus around the surgical site.

If you have any of these symptoms you should contact the NHS patient helpline on 111 for further information.

What to do next

If you're well and have no symptoms, you don't need to do anything immediately. Be aware of the symptoms, particularly because the infection can take up to five years after surgery to appear.

If you've had one of the types of open-heart surgery that carries this very low risk of infection, your GP will have been contacted separately and asked to make a note on your records. When you next visit your GP, we recommend you ask your GP to check that the information has been added to your patient record. You don’t need to make an appointment just to do this if you are otherwise well.

If you feel unwell and have one or more of the symptoms listed above, please contact the NHS patient helpline on 111 for further information.

If you're diagnosed with the infection, treatments are available.

In the event that any further heart surgery may be recommended in the future, it's important to stress that the risks of infection from this bacteria are very low and much lower than the risks involved in not having appropriate treatment.

Further information

Find out more on the NHS website, which includes a video featuring a cardiac surgeon explaining the use of the heater cooler device and the risk of infection, or by calling NHS 111.