Failure among Patients with Non-Tuberculous Mycobacterial Infections in Skin, Soft Tissue, and Musculoskeletal System in Southern Taiwan, 2012-2015

Background: The incidence of non-Tuberculous mycobacterial (NTM) infections of the skin, soft tissue, and musculoskeletal system (SSTI) has increased over the past two decades, however, relatively few studies have documented the reasons for the reported increase. Specifically, no standardized treatment protocols have been adopted, therefore, clinical prognosis of the patients with NTM SSTI has thus far remained uncertain. In our study, we sought to identify risk factors for treatment failure in southern Taiwan. Methods: Patients with NTM SSTI, who received treatment between 2012 and 2015 were included in this retrospective study; detailed medical records, images, tissue specimens for culture, and pathology reports were collected for further analysis. Risk factors for treatment failure were determined using multivariable logistic regression. Results: Forty-Two patients (16 females, 26 males; aged 58 ± 14 years) with NTM SSTI were included in the study. Isolated mycobacterial species included Mycobacterium abscessus complex, Mycobacterium marinum, Mycobacterium kansasii, Mycobacterium avium-intracellulare complex (MAC), Mycobacterium fortuitum, Mycobacterium gordonae, Mycobacterium haemophilum, Mycobacterium peregrinum, and Mycobacterium chelonae. The incidence of NTM SSTI was 23.6 per 100,000 inpatients. The sites of infection included the hand/wrist areas, spine, feet, lower legs, femur, knees, shoulders, and elbows, in 15, 6, 5, 5, 4, 3, 2, and 1 patients, respectively. The time interval between culturing the specimens and diagnosis averaged 21.2 ± 11.4 days. The main risk factors for treatment failure included treatment delays exceeding two months and infection with Mycobacterium abscessus complex. Conclusions: Improved clinical outcome of NTM with STI may be achieved by identifying the causative NTM species, and by initializing appropriate pharmacotherapy and surgical intervention. Non-Tuberculous mycobacterial infection should be included in the differential diagnosis of SSTI and it is recommended that patients with an increased risk of treatment failure should receive prolonged antibiotic treatment and prompt surgical intervention upon diagnosis or indication of NTM infections.