Nontuberculous Mycobacterial Infection Risk Factors Not Easily Characterized

Nontuberculous mycobacterial (NTM) pleural infections with a poor prognosis and high risk of complications can affect patients regardless of whether or not they are immunocompromised, have chronic lung disease, or have concurrent NTM pulmonary infection. These are among the findings of a systematic review and meta-analysis published in Respiratory Medicine.

Previous small case series and case reports depict NTM pleuritis with a highly variable clinical course, suggesting mortality may occur in more than a third of cases.

Investigators in the current review detailed patient characteristics, clinical presentations, and outcomes in those with NTM pleuritis.

The investigators searched the PubMed database for articles in English, Hebrew, and French from 1980 to 2021, ultimately identifying 206 cases of NTM pleural infections (42% women; mean 57.5 years of age [range 9-87 years]) in 59 studies. The meta-analysis included 47 single case reports, 8 small series (33 cases), and 4 series (126 cases). A significant portion of these cases (43%) involved patients who were immunosuppressed, and 43% involved patients with chronic lung disease; however, neither of these factors were present in 32% of NTM pleuritis cases identified. The investigators noted that 27 cases involved a current malignancy, 22 involved patients who were diabetic, 6 involved patients with HIV/AIDS, and patients in 59 of the cases had a history of smoking.

Notably, patients in 67% of the cases had concurrent pulmonary NTM infection in addition to the pleural infection. An extra-pulmonary site of NTM infection was found in 18 cases, and the pleural infection was the sole manifestation of NTM disease in 29% of cases.

Investigators found Mycobacterium avium complex to be the most common mycobacterium (65%) associated with the cases they identified. Affected patients needed anti-NTM chemotherapy (79%), surgical intervention (26%), and pleural effusion drainage (53%). The mortality rate was 24%. There were 16% of cases with empyema, 16.5% of cases with bronco-pleural fistula, and 40% with pneumothorax.

Review limitations include missing data in multiple studies; significant variation in follow-up time leading to underreporting of outcomes; the use of articles published in 3 languages only; and the preponderance of cases (more than 90%) from East Asia, making generalizability difficult.

“Key findings are that while the majority of these infections occur in patients who are immunosuppressed, and/or have chronic lung disease, about a third of cases

occur in individuals who do not have either of these risk factors,” review authors noted. “Most [patients] have a concurrent NTM pulmonary parenchymal infection but some

have isolated NTM pleuritis.” The authors further stressed that the prognosis for these patients was poor, and that the infections carried “a high risk of complications requiring surgical interventions in addition to anti-NTM chemotherapy.”

This article originally appeared on Pulmonology Advisor