Mycobacterium avium (MAC) lung disease in post-COVID-19 bronchiectasis: a need for caution as a potential risk factor for MAC infection

Bronchiectasis due to previous tuberculosis is known to precede Mycobacterium avium (MAC) lung disease. Coronavirus disease 2019 (COVID-19) is an emerging infectious disease, and residual bronchiectasis following COVID-19 is common as well as tuberculosis. However, there have been no reports documenting MAC lung disease secondary to bronchiectasis post-COVID-19 until now. We present the case of an 84-year-old patient on steroid therapy for alveolar hemorrhage who developed COVID-19, resulting in residual bronchiectasis. Despite no evidence of chronic airway infection immediately prior to the COVID-19 infection, the patient developed pulmonary MAC disease 2 years later. This is the first report of MAC lung disease secondary to bronchiectasis following COVID-19. Similar cases are likely to occur in the future, necessitating caution.