[A clinical study of pulmonary Mycobacterium abscessus infection]

Pulmonary Mycobacterium abscessus infection is resistant to many antibiotics and is difficult to treat. We retrospectively analyzed the clinical characteristics of pulmonary infection due to M. abscessus. Eleven cases diagnosed as having pulmonary M. abscessus infection at Osaka Red Cross Hospital from January. 2008, to June, 2012 were enrolled in this study. The average age of the 11 cases was 63 years (all were females). Nine cases showed underlying diseases, comprising 5 cases with Mycobacterium avium complex lung infection, 3 with old pulmonary tuberculosis, and 3 with bronchiectasis. The radiological examination revealed that 10 cases showed the small nodular type, 7 showed the bronchiectatic type, 4 showed a cavity lesion and 4 showed infiltrative shadows. A microbiological definite diagnosis was made from sputum in 10 cases and bronchial lavage fluid in one. As treatment for M. abscessus pulmonary infection, combined multi-drug chemotherapy was carried out in 7 of the 11 cases. No patients were successfully treated with antibiotics alone, whereas 4 patients had no exacerbation of radiological findings without any treatment. One patient received antibiotics including clarithromycin, amikacin and levofloxacin for 2 to 12 months following surgical excision and her sputum cultures have been maintained as negative over the long-term. During the study, none of the 11 patients were known to have died. In this study, we found that M. abscessus pulmonary infection is more common among females, and is found frequently in patients with M. avium complex lung infection. We also found that the clinical course of M. abscessus pulmonary infection was different among patients. We think this is because M. abscessus was shown to comprise three closely related species. M. abscessus is extremely difficult to eradicate, and surgical resection of localized disease or the main lesion or cavity may be significantly effective in preventing the progression of disease.