Dr. Fine, does the positive BAL culture indicate an active MAC infection?
►Dr. Fine. Yes, based on these updated data, the patient has an active MAC infection. Active infection is defined as symptoms or imaging consistent with the diagnosis, supporting microbiology data (either 2 sputum or 1 BAL sample growing MAC) and the exclusion of other causes. Previously, this patient grew MAC in just one expectorated sputum; this did not meet the microbiologic criteria. Now sputum has grown in the BAL sample; along with the CT imaging, this is enough to diagnosis active MAC infection.
Treatment for MAC must consider the details of each case. First, this is not an emergency; treatment decisions should be made with the rheumatologist to consider the planned immunosuppression. For example, we must consider potential drug interactions. A specific point should be made of the use of tumor necrosis factor (TNF)-α inhibition, which data indicate can reactivate TB and may inhibit mechanisms that restrain mycobacterial disease. Serious cases of MAC infection have been reported in the literature in the setting of TNF-α inhibition.5,6 Despite these concerns, there is not a contraindication to using these therapies from the perspective of the active MAC disease. All of these decisions will impact the need to commit the patient to MAC therapy.
►Dr. Swamy. Dr. Fine, what do you consider prior to initiating MAC therapy?
► Dr. Fine. The decision to pursue MAC therapy should not be taken lightly. Therapy often entails prolonged multidrug regimens, usually spanning more than a year, with frequent adverse effects. Outside of very specific cases, such as TNF-β inhibition, MAC is rarely a life-threatening disease, so the benefit may be limited. Treatment for MAC is certainly unlikely to be fruitful without a diligent and motivated patient able to handle the high and prolonged pill burden. Of note, it is also important to keep this patient up-to-date with influenza and pneumonia vaccination given her structural lung disease.
►Dr. Swamy. The decision is made to treat MAC with azithromycin, rifampin, and ethambutol. The disease is noted to be nonfibrocavitary. The patient underwent monthly liver function test monitoring and visual acuity testing, which were unremarkable. Dr. Fine, can you describe the phenotypes of nontuberculous mycobacterial (NTM) disease?
►Dr. Fine. There are 3 main phenotypes of NTM.3 First, we see the elderly man with preexisting lung disease—usually chronic obstructive pulmonary disease—with fibrocavitary and/or reticulonodular appearance. Second, we see the slim, elderly woman often without any preexisting lung disease presenting with focal bronchiectasis and nodular lesions in right middle lobe and lingula—the Lady Windermere syndrome. This eponym is derived from Oscar Wilde’s play “Lady Windermere’s Fan, a Play About a Good Woman,” and was first associated with this disease in 1992.7 At the time, it was thought that the voluntary suppression of cough led to poorly draining lung regions, vulnerable to engraftment by atypical mycobacteria. Infection with atypical mycobacteria are associated with this population; however, it is no longer thought to be due to the voluntary suppression of cough.7,8 Third, we do occasionally see atypical presentations, such as focal masses and solitary nodules.
►Dr. Swamy. At 1-year follow-up she successfully completed MAC therapy and noted ongoing control of rheumatoid symptoms.