Mycobacterium chimaera: infections linked to heater cooler units

Guidance for healthcare professionals on infection control and clinical aspects of M. chimaera infection associated with cardiopulmonary bypass.

Mycobacterium chimaera (M. chimaera) is an environmental non-tuberculous mycobacteria belonging to the Mycobacterium avium complex. It has been recognised as a cause of endocarditis, severe disseminated infection and chronic sternal wound infection in patients who have undergone cardiothoracic surgery.

M. chimaera may manifest many years after surgery undertaken on bypass. Investigations in multiple countries shows this is likely to be transmitted from heater cooler units, which are part of the cardiopulmonary bypass equipment.

The risk of infection is low and control measures are already in place. However, M. chimaera infection can have an insidious and non-specific presentation, is not always identified through conventional microbiology, and requires specific treatment.

As of 13 November 2020, there were 48 cases of M. chimaera infection following surgery on cardiopulmonary bypass, of which 32 were known to have died. The median interval between surgery and diagnosis is 24 months but ranges from less than 1 to 154 months.

Guidance for healthcare providers and health professionals

NHS.UK has guidance for the public about M. chimaera infection.

Published 9 June 2015
Last updated 7 December 2020 + show all updates
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  9. Confirmed current UK case numbers.

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  13. Added guidance for GPs.

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  15. Investigation reports section updated

  16. Added a link to the finding of a UK investigation.

  17. Updated with latest version of guidance for healthcare providers and added guidance for healthcare professionals in secondary care.

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  20. First published.