In our database, there were 745 patients meeting ATS criteria for diagnosis of atypical mycobacterial pulmonary infection, of which 554 (74%) were infected with MAC based on available microbiologic data. A total of 98 patients met criteria for radiographically localized MAC infection and received medical treatment. Of these, 16 underwent surgical resection. Table 1 outlines demographics, comorbidities, medical treatment administered, and information regarding surgical resection. Table 2 outlines complications and outcomes for 16 surgically treated patients. Overall, surgical resection was performed rarely: in 16/554 (2.9%) of MAC patients meeting ATS criteria and 16/98 (16%) of the subset with localized disease requiring medical treatment. Of the 16 surgically treated patients, 13 underwent one lung resection. The remaining three patients underwent two resections at separate time intervals for progression of disease. The majority 10/16 (63%) of patients had surgical resection of disease from one lobe and the other six patients had a multi-lobar resection. The indication for surgery was listed as disease refractory to medical therapy in 9/16 (56%) patients and in 6/16 (38%) surgical resection was described as adjunct to medical therapy. For the remaining patient, the indication for surgery was described as hemoptysis with perioperative antimycobacterial administration. Eleven patients had cavitary lesions resected, 4 had bronchiectasis resected, 2 had consolidation resected, and 1 had an abscess resected. Postoperatively there were no bleeding events requiring repeat surgery. Only one of the 16 patients developed a bronchopleural fistula (6%) and another developed a chyle leak (6%).
The baseline characteristics of the surgically treated groups are compared to the medically treated group with disease in Table 2. In univariate analysis on treatment outcome there was no significant difference in microbiologic response rate (odds ratio 0.49, 0.1-2.41) and 2-year all-cause mortality (odds ratio 0.87, 0.18-4.32) between surgical and medical cohorts. The composite outcome of 2-year mortality and lack of microbiological response showed no significant difference between the two groups after adjustment for age and gender (multivariate logistic regression OR=0.45, 0.09-1.57).
Brief Case Presentation
A 30 to 40-year-old patient with a 25 pack-year history of smoking, hypertension, seasonal allergies, and gastroesophageal reflux disease presented with 5-6 months of night sweats, associated weight loss, and chronic productive cough with brown sputum. Prior evaluations for these symptoms about a month prior to presentation were notable for chest radiograph initially visualizing left upper lobe opacities, but interval imaging at the time of presentation showed progression to left upper lobe cavitary lesion. Subsequently, this was confirmed on computed tomography of the chest with revisualization of left upper lobe cavitary lesion, with multiple satellite nodules. Initial induced sputum was notable for abundant 3-4+ acid fast bacilli on two subsequent days. Follow-up bronchoscopy and bronchioalveolar lavage with cultures confirmed a diagnosis of Mycobacterium Avium Complex pulmonary infection. Additional etiologies of cavitary lesions were excluded with negative tuberculin skin testing, negative coccidiosis serum titers, and negative ANCA testing. Susceptibility testing showed MAC susceptibility to clarithromycin.
About a month after initial presentation the decision was made to initiate medical therapy with Azithromycin, Ethambutol, and Rifampin. She tolerated medical therapy well with no hearing problems, no tinnitus, no imbalance, no visual changes, no color vision problems, no nausea, no vomiting, and no diarrhea. About 2 months after initiation of medical therapy surveillance mycobacterial cultures were negative. Initial surveillance chest computed tomography 4 months after therapy initiation showed an interval response to therapy, marked by decrease in the number of satellite nodules and improvement in the cavitary wall thickness and reduced inflammation. Interval imaging 11 months after initiation of therapy, however, showed a persistence of the cavitary lesion. Given persistent unresolved symptoms and the radiographic findings she was referred for surgical evaluation.
With well localized disease, she was deemed a candidate for limited parenchymal surgical resection with curative intent. She underwent a surgical wedge resection of the left upper lobe cavitary 14 months after therapy initiation without any post-operative complications. She received 4 weeks of preoperative and postoperative intravenous amikacin. On pathologic examination, the cavitary lesion was tan-white with a firm wall containing necrotic debris; margins were 0.4 cm and the uninvolved parenchyma was normal without masses. Mycobacterial organisms were visible with Acid fast stain.
In addition to 4 weeks of post-operative intravenous amikacin, a plan was made to continue Azithromycin, Ethambutol, and Rifampin for 1 year post-operatively, but the patient terminated therapy at 6 months for non-medical reasons. Intermittent surveillance cultures were obtained for 16 months after resection remained negative. At the time of follow-up 16 months of after resection she remained asymptomatic without cough, night sweats, or weight loss.