Mycobacterium chimaera encephalitis following cardiac surgery in three adult immunocompetent patients: first detailed neuropathological report

• Published in: Canadian journal of neurological sciences 2019-09, Vol.46 (s2), p.S65-S66
• Main Authors: Das, SK, Lau, D, Cooper, R, Chen, J, Sim, VL, McCombe, JA, Tyrrell, GJ, Bhargavi, R, Adam, B, Chapman, E, Garady, C, Antonation, K, Ip, S, Saxinger, L, van Landeghem, FKH
• Format: Article
• Language: English
• Subjects: Abstracts; Encephalitis; Heart surgery; Immunocompetence; Infections; Neuropathology; Session 4: Infectious/Immune mediated Neuropathology sand Neuromuscular Neuropathology
• ISSN: 0317-1671; 2057-0155
• DOI: 10.1017/cjn.2019.270

Non-tuberculous mycobacterium encephalitis is rare. Since 2013, a global outbreak of Mycobacterium chimaera infection has been attributed to point-source contamination of heater cooler units used in cardiac surgery. Disseminated M. chimaera infection has presented many unique challenges, including non-specific clinical presentations with delays in diagnosis, and a high mortality rate among predominantly immunocompetent adults. Here, we describe three patients with fatal disseminated Mycobacterium chimaera infection showing initially non-specific, progressively worsening neurocognitive decline, including confusion, delirium, depression and apathy. Autopsy revealed widespread granulomatous encephalitis of the cerebrum, brain stem and spinal cord, along with granulomatous chorioretinitis. Cerebral involvement and differentiation between mycobacterial granulomas and microangiopathic changes can be assessed best on MRI with contrast enhancement. The prognosis of M. chimaera encephalitis appears to be very poor, but might be improved by increased awareness of this new syndrome and timely antimicrobial treatment.