Bacteraemia caused by Mycobacterium abscessus subsp. abscessus and M. abscessus subsp. bolletii: Clinical features and susceptibilities of the isolates

Mycobacterium abscessus complex (M. abscessus subsp. abscessus and M. abscessus subsp. bolletii) is an emerging pathogen causing various human infections. However, few studies have focused on M. abscessus complex bacteraemia with detailed species differentiation. The clinical characteristics of patients with bacteraemia due to M. abscessus complex treated at National Taiwan University Hospital from 2005–2012 were evaluated. Species identification was performed by molecular methods, and minimum inhibitory concentrations (MICs) were determined using a Sensititre RAPMYCO Panel Test for preserved M. abscessus complex isolates. During the study period, 15 patients with M. abscessus complex bacteraemia were found but only 14 isolates from 13 patients were preserved for analysis. One patient had two episodes of bacteraemia (one caused by M. abscessus subsp. bolletii and one by M .abscessus subsp. abscessus with a 9-month interval). Of the remaining 12 patients, 9 patients had M. abscessus subsp. bolletii bacteraemia and 3 had M .abscessus subsp. abscessus bacteraemia. Patients were mainly middle-aged adults with various co-morbidities. Steroid usage and malignancy (5/15) were the most common immunocompromised statuses, followed by diabetes mellitus (4/15). Surgical wound infection was the most common infection foci in all patients (5/15), particularly in M. abscessus subsp. bolletii bacteraemia patients. Clarithromycin and tigecycline exhibited good in vitro activities. Overall, the 14-day mortality was 20% (3/15). M. abscessus complex bacteraemia should be considered an emerging opportunistic infection in immunocompromised hosts. Clarithromycin and tigecycline have potent in vitro activities and are promising agents for treating infections due to M. abscessus complex.