Mycobacterium avium intracellulare Complex Causes Lung Infection

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A 76-year-old female is admitted to the pulmonary unit in the hospital due to shortness of breath, recurrent cough, fatigue and weight loss. Patient has a past medical history of persistent cough and excess phlegm or sputum (bronchiectasis). Upon her admission a chest x-ray and computerized tomography (CT) scan was performed.  

Lab Testing

Based on the clinical presentation of the patient, a bronchoalveolar lavage (BAL) specimen was obtained for bacterial culture. BAL is a procedure where sterile liquid is injected deep into lung tissue and retrieved for further analysis. Bacteriology culture consisted of plating the BAL on agar media such as chocolate, blood and MacConkey agar for bacteria and 7H11 Middlebrook agar for mycobacteria. Routine bacteriology media was negative for growth, however 7H11 Middlebrook agar was positive for colonies, which were identified as Mycobacterium avium intracellulare Complex (MAI).

Cause of Symptoms

MAI are commonly found in the environment but can cause infections in the human host. Infections typically present in lung, skin and soft tissue but disseminated (blood) infections can also occur. Patients with predisposing medical disease, such as bronchiectasis, are at higher risk for acquiring this infection. MAI infection can cause chronic pulmonary disease, lymphadenitis and disseminated disease especially in immunodeficient patients. Of interest, MAI infection has been seen with frequency in elderly woman who appear to have no predisposing conditions. This is referred to as Lady Windermere’s Syndrome, coined from an Oscar Wilde play which portrayed a woman who involuntarily suppressed her cough. The hypothesis is that cough suppression in this patient population leads to the development of a non-specific inflammatory process in poorly draining lung regions, which predisposes the host to MAI infection. 


Patient was treated with a daily 3 drug regimen (azithromycin, ethambutol, rifampin) for 3 months and after clinical improvement, was transitioned to a therapy interval of 3 times a week. Prolonged therapy is often necessary for complete resolution of MAI infection.  

Contact Information

Nicole Jackson,