Fast update of undetected Mycobacterium chimaera infections to reveal unsuspected cases

Summary Mycobacterium chimaera is involved in a worldwide alert due to contaminated heater–cooler units. A real-time polymerase chain reaction (RT-PCR)-based procedure was implemented to survey undetected cases of M. chimaera infection. PCR was negative in the 59 prosthetic heart valves from patients with PCR-16SrRNA-negative infective endocarditis. PCR identified  M. chimaera in one of 15 clinically significant retrospective Mycobacterium avium–Mycobacterium intracellulare complex isolates, which corresponded to a patient who had undergone heart valve replacement in a different institution. Whole-genome sequencing demonstrated that he was the first case in Spain with involvement of the strain responsible for the global outbreak. These results highlight the relevance of retrospective tracking for undetected M. chimaera infections.