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Following the reported link between heater–cooler unit (HCU) colonisation with and endocarditis, mycobacterial sampling of all HCUs in use in Western Australia was initiated from August 2015, revealing colonisation in 10 of 15 HCUs. After was isolated from a pleural biopsy from a cardiothoracic patient who may have been exposed to a colonised HCU, a whole genome sequencing investigation was performed involving 65 specimens from 15 HCUs across five hospitals to assess if this infection was related to the HCU. Genetic relatedness was found between the 10 HCU isolates from four hospitals. However the isolate from the cardiothoracic patient was not genetically related to the HCU isolates from that hospital, nor to the other HCU isolates, indicating that the HCUs were not the source of the infection in this patient.


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