18 Cases of pulmonary Mycobacterium abscessus: Clinical difference depending on the presence or absence of Mycobacterium avium complex.

ABSTRACT

BACKGROUND AND OBJECTIVES: It can be difficult to treat respiratory tract infections caused by Mycobacterium abscessus (M. abscessus) as there is no established treatment strategy. Complications involving other nontuberculous mycobacterial infections such as Mycobacterium avium complex (MAC) are also commonly observed. METHODS: We investigated the clinical background and course of 18 cases of pulmonary M. abscessus infection treated over 8 years at Kurashiki Central Hospital. Radiological evaluation was performed using NICE scoring system, a method of semi-quantitative evaluation of imaging findings of pulmonary MAC infection. RESULTS: The mean age of the 18 patients (males, 6; females, 12) was 74.7 years. The median follow-up period was 1316 days (95% confidence interval; 720-1675 days), and 11 patients were concomitantly infected with pulmonary MAC. Among the patients that underwent antibacterial treatment for M. abscessus, there was one MAC-complication case and one non-MAC-complication case. All MAC-complication cases underwent antibacterial treatment including clarithromycin. Chest X-ray NICE scores for all cases were 8.50 ± 5.45 and 10.94 ± 6.03 at baseline and follow-up, respectively (p = 0.0063). For MAC-complication cases, scores were 8.36 ± 4.74 and 12.00 ± 6.02 at baseline and follow-up, respectively (p = 0.00818), and for non-MAC-complication cases, scores were 8.71 ± 6.82 and 9.29 ± 6.13 at baseline and follow-up, respectively (p = 0.356). MAC-complication cases were significantly further exacerbated than non-MAC-complication cases (p = 0.027). CONCLUSIONS: Some cases of pulmonary M. abscessus infection progressed well without undergoing antibacterial treatment. In particular, results suggested that the clinical course of MAC-complication and non-MAC-complication cases differs.