Postcesarean section wound infection caused by Mycobacterium massiliense

Background/Purpose Mycobacterium abscessus subsp. massiliense (a subspecies of the M. abscessus complex) is a rare causative agent of surgical site infection after cesarean section (C section). We tried to seek the common source of infection and unravel the optimal treatment modalities. Methods From September 2009 to October 2012, four postpartum women developed C-section wound infections caused by M. massiliense. Speciation of the four isolates was identified using of hsp65, rpoB, and secA1 partial gene sequencing and the Basic Local Alignment Search Tool. The erm(41) and rrl genes were detected for the possibility of inducible macrolide resistance. Pulsed-field gel electrophoresis was used as a tool of molecular epidemiology. All patients underwent intensive intravenous and oral antimycobacterial regimens. Of these patients, three underwent debridement at least once. Results All four isolates were identified as M. abscessus subsp. massiliense. All of the isolates harbored a truncated erm(41) gene without rrl gene mutations, which explains the susceptibility to clarithromycin and azithromycin. Three isolates were indistinguishable by DNA strain typing, and the fourth strain was clonal with the other three strains. Their infections were not improved in spite of teicoplanin treatment initially. These patients underwent antimycobacterial regimens with/without surgery and were all cured. Discussion Teicoplanin treatment failure, painful cutaneous nodules, and persistent wound drainage alerted us to the possibility of nontuberculous mycobacterial skin and soft tissue infection. Accurate identification of subspecies, detection of drug resistance genes, susceptibility testing, and optimal antimycobacterial agents with/without surgical debridement are warranted for successful treatment.