Non tuberculous mycobacteria in surgical wounds- a rising cause of concern?

Introduction: The non-tuberculous mycobacteria (NTM) have emerged as important opportunistic pathogens in the recent years. The NTM are rapid growing mycobacteria (RGM), which include Mycobacterium fortuitum and M. chelonae and are grouped as M. fortuitum-chelonae complex. Non-healing postoperative wound infections that do not respond to antibiotics used for pyogenic infections and having sterile routine aerobic cultures should raise a suspicion of NTM.

Patients And Methods: All patients with post operative wound infection over a five year period were included in the study. All wound infections were evaluated with wound culture and sensitivity and treated with appropriate antibiotics. All infections with underlying mesh were initially managed with dressings/debridement, long term antibiotics. Explantation of the mesh was to be used as a last resort.

Results: We analyzed the records of patients with post operative wound infections who had wound cultures taken and found that 16 of our patients had initial sterile cultures. In all these cases, wound infection manifested itself as discharging sinuses between 2-3 weeks after surgery. Of these seven patients grew NTM on their repeat cultures. The commonest organism isolated was M. fortuitum (57%). The commonest antibiotic used for treatment was Tab Clarithromycin and the mean duration of treatment was 6 to 9 months. No patients required debridement or removal of mesh.

Discussion: NTM infections in post operative wound though rare should be suspected in all post operative wound infections which occurs late, lack local and systemic signs of pyogenic infections and have sterile cultures. High index of suspicion for NTM infection will allow identification and treatment of these patients with long-term antimicrobial therapy alone without the need for surgical explantation of the mesh.