Rapidly growing nontuberculous mycobacteria (RGM) can produce numerous types of manifestations including a pulmonary infection. Managing a pulmonary infection due to RGM is unusually difficult to treat because the organism is invariably resistant to traditional antituberculous drugs and has a varying susceptibility to other antibiotics. The experiences of treatments for a RGM pulmonary infection with various antibiotics are also limited. This study evaluated the clinical manifestations, treatment, and the therapeutic outcomes of a RGM pulmonary infection.

Fifty-four cases with RGM from respiratory specimens were identified between November of 1996 and September of 2002 in the Asan medical center. The medical records and radiographic findings in 20 patients who fulfilled the diagnostic criteria of nontuberculous mycobacteria (NTM) pulmonary disease by ATS guidelines. The clinical, laboratory, and radiological parameters between subgroups.

Of the 20 patients, 15 were female. The mean age was 57.7 yrs (±7.5), and all of the patients had a history of pulmonary tuberculosis. Most (90%) had an underlying lung disease. The majority of the isolates (80%) were M. abscessus. Chest radiography showed bilateral involvement in 80% of the patients. Bronchiectasis and multiple nodules were the main findings. Cavitation was present in 35% of the patients. Even though 70 % of the patients received antituberculous drugs prior to the correct diagnosis, all of the patients eventually received antibiotics. A mean of 3.5 antibiotics were given for an average of 439 days(±168). After completing treatment, nine patients showed improvement after a mean 591(±311) days of treatment, whereas the antibiotic treatment was unsuccessful in 2 patients.

Many patients with a RGM pulmonary infection show an atypical pattern of radiological findings (bronchiectasis and multiple centrilobular nodules). It is very important to differentiate between M. tuberculosis and NTM and to identify the causative organisms among the NTM because a misdiagnosis can lead to an inappropriate and prolonged treatment. Combined antibiotic treatment yielded promising results, and is recommended for treating patients with a RGM pulmonary infection.