Nontuberculous mycobacteria (NTM) are ubiquitous in the environment and found commonly in respiratory specimens. In many laboratories, the majority of mycobacteria recovered from respiratory samples are NTM. The term colonization has been used when NTM are recovered more than once and no specific pulmonary disease can be demonstrated. It is not clear whether a low-grade infection exists or if the secretions are contaminated by environmental organisms. The clinical presentations of pulmonary MAC may vary. The three most common forms of presentations in immunocompetent host are 1) Preexisting lung disease (COPD, old TB) with fibrocavitory or/and reticulonodular appearance -, 2) No preexisting lung disease: focal bronchiectasis and nodular lesions in right middle lobe and lingula: the “Lady Windermere Syndrome” and 3) Atypical presentations like focal masses and solitary nodules. In severely immunocompromised hosts, disseminated MAC is more common. In 1997, ATS issued a guide to diagnose pulmonary disease caused by NTM and one exclusion criteria was the presence of other diseases such as TB. Studies on coexisting lung infection from NTM and MTB and its complications are limited with no clear guidelines for management.
22 year old African American female without prior medical history presented with a 3 weeks of fever and productive cough. HIV test was negative twice and Tuberculin Skin Test (TST) showed no induration. The patient was cachectic, Chest X-Ray and Chest-CT showed consolidation of the right lung and bronchiectasis. The patient was admitted with diagnosis of pneumonia and started on Ceftriaxone/ Azithromycin which was later changed to Gatifloxacin without improvement of symptoms. Several sputum specimens collected for Acid Fast Bacilli (AFB) smear were negative. Bronchoalveolar lavage (BAL) and trans-bronchial biopsy were smear-positive for AFB and pathology showed granulomatous inflammation. Rifampin, Isoniazid, Pyrazinamide and Ethambutol (RIPE) was started. On day 13 of admission the patient had a right-sided pneumothorax which required a chest tube. Later three sputum and BAL/Biopsy cultures were positive for MAC, all other cultures were positive for MTB(pan-sensitive). Because of the patient’s persistent high-grade fever and hypoxemia after 4 weeks on RIPE,empiric treatment for MAC with Clarithromycin and Rifabutin was added and Rifampin was discontinued. The patient improved with combined treatment for MTB and MAC. She was discharged home after 2 months of treatment. She returned 3 days later with a new right-sided pneumothorax. Chest CT showed development of a bronchopleural fistula. The patient is being evaluated for surgical pleurodesis.
The presence of M. tuberculosis in a pulmonary specimen makes a diagnosis of tuberculosis disease and the presence of MAC in such a setting is assumed to be colonization. The treatment of pulmonary disease caused by NTM in immunocompetent hosts can be difficult because of the length of treatment and side effects, and the addition of medication for MAC when MTB is isolated is usually not recommended. With the rise of awareness of NTM as a pathogen, this concept may change in situations where improvement in symptoms are not seen with anti-TB treatment alone. This patient may represent one of those cases. Most likely the patient improved from the anti-TB treatment but the addition of anti-MAC drugs may have played a role.
Further studies are needed when coinfection with NTM and MTB are present in immunocompetent individuals. Some patients in this setting may require combined treatment. The length of treatment needs to be evaluated case-by-case, until more studies become available.
J. Iqbal, None.