Updates in Nontuberculous Mycobacterial Lung Infections

Nicholas Gross, MD, PhD


December 18, 2015

Pulmonary Disease Due to Nontuberculous Mycobacteria: Current State and New Insights

McShane PJ, Glassroth J
Chest. 2015;148:1517-1527

Study Summary

Nontuberculous mycobacterial (NTM) infections of the lungs are seldom effectively diagnosed and treated before much time has passed, and ineffective medications have been tried. The symptoms, cough, and fatigue resemble those of more common respiratory conditions.

In a recent study,[1] Medicare claims data were used to compare the demographics, treatment characteristics, and utilization patterns of 738 patients with NTM infections with a matched control group of 5166 otherwise similar persons. Prediagnosis comorbid conditions were up to 35 times more common, respiratory symptoms and signs were 16 times more common, and prediagnostic resource utilization was 11 times more common in the NTM group than the control group (all P <.001). The delay in diagnosis is typified by the results.


The term "nontuberculous mycobacteria" encompasses more than 140 species and subspecies of mycobacteria—Mycobacterium avium complex, Mycobacterium kasasii, and Mycobacterium abscessus being the most common. The lungs can be infected, presumably by inhalation, but humans can also be infected in a variety of other ways. There are reports of postoperative infections and infections of the skin, uterus, joints, middle ear, lymph nodes, and indwelling catheters. Infection can occur in immune-competent as well as immunocompromised patients.

The prevalence of NTM-related lung disease appears to be increasing.[1] Recently, a cluster of NTM infections related to heater/cooler devices was reported to the Centers for Disease Control and Prevention,[2] and the US Food and Drug Administration issued a safety communication.[3] NTM infections occurred in patients who had undergone cardiopulmonary bypass involving a heater/cooler device within the previous 4 years.

The current report illustrates the typical delay in diagnosing and treating NTM-related lung infections, and the need for awareness of the problem and institution of appropriate diagnostic tests and treatment. Diagnosis is typically made from microbiologic tests; like Mycobacterium tuberculosis, NTM organisms are slow growers. Final species identification may require nucleic acid probes. Treatment guidelines are available[4] and recommend triple therapy with the same drugs as for M tuberculosis, namely a combination of three drugs from the list of azithromycin or clarithromycin, ethambutol, rifampin, and amikacin. Poor compliance and noncompliance with therapy are major concerns.


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