Nontuberculous mycobacterial infection after lung transplantation: a report of four cases

Nontuberculous mycobacterium (NTM) infection in a patient in an immunosuppressed state caused by increased use of immunosuppressive or biological agents is a serious clinical problem. Mycobacterium avium complex is the most common involved pathogen, followed by Mycobacterium abscessus (MABSC), while Mycobacterium kansasii is not a major concern. The rate of infection rate in lung transplant recipients is reported to range from 1.5-22.4%.

We report here four cases of NTM pulmonary infection and disease among 63 patients who underwent lung or heart-lung transplantation at our hospital. Those four occurred following living-donor transplantation in two patients, one with pulmonary arterial hypertension and one with bronchiectasia, and deceased donor lung transplantation in two patients, lymphangioleiomyomatosis and interstitial pneumonia, respectively. NTM was not detected in any of the patients prior to transplantation. The involved pathogens were Mycobacterium gordonae in one, MAC in one, and MABSC in two of these patients, which were isolated from broncho-alveolar lavage (BAL) in two and sputum in two. The one case of MAC and two of MABSC were symptomatic with consolidation shown in chest CT images indicating possible pneumonia, while the one with M. gordonae had no symptoms and was detected by surveillance BAL. Onset time from detection of NTM was greater than 3 years in the three with MABSC and M. gordonae and less than 3 years in the one with MAC. Each patient required a decrease in immunosuppressive agents according to their condition, while antibiotics therapy was performed in the three who were symptomatic. Sputum culture findings became negative after several months and were maintained thereafter in all.

An NTM infection leading to pulmonary disease can occur at any time following lung transplantation. Treatment should be considered depending on the involved pathogens, individual status, and disease severity.