Published: March 10th, 2017
Revised: March 29th, 2017
Mycobacterium chimaera (M. chimaera) is a non-tuberculous mycobacteria (NTM) which has been implicated as a causative agent of a small number of infections post-surgery. NTM are common inhabitants of the environment and have been cultured from water, soil, and animal sources worldwide. They are known to be opportunistic pathogens, mostly affecting the immunocompromised or immunodeficient. M. chimaera has been found in heater-cooler devices used to regulate patients’ blood temperature during cardiopulmonary bypass. Alerts from Health Canada, CDC, FDA and other health authorities worldwide have been issued based on reports suggesting that invasive infections have resulted from exposure to aerosolized M. chimaera from heater cooler units during cardiac surgery.
Given the dependency on heater-cooler units for improving surgical outcomes, there is a critical need to reduce downtime. The standard, culture-based analytical techniques are very useful for the identification of Mycobacterium in general, but have the limitations of not always being specific and taking up to four weeks for results. The need arose for a fast testing solution that the traditional culture techniques could not meet; to determine the baseline contamination of devices as well as to confirm disinfection. Polymerase Chain Reaction (PCR) based tests specific for M. chimaera decreases testing time from several weeks to several hours by allowing the direct detection of M. chimaera DNA from mixed samples without the need for culturing.
Mycobacterium chimaera testing by RT-PCR
Real-time PCR (RT-PCR) is a rapid and accurate tool for the detection of M. chimaera DNA. We developed a M. chimaera RT-PCR test based on the methods from a research group at the University of Melbourne. It has been internally validated using the M. chimaera type strain and real-world samples. This method represents the state-of-the-art having been released publicly in February of 2017.
It is important to note that this method cannot distinguish between living and dead cellular material. Analytical results will be reported as positive or negative for M. chimaera DNA.