Flushing Out the Culprit: Mycobacterium abscessus as a Cause of Recurrent Fistula-in-ano

Complex fistula-in-ano (FIA) presents significant surgical challenges, with recurrence often driven by inflammatory, anatomical, and microbiological factors. Mycobacterium abscessus, a multidrug-resistant nontuberculous mycobacterium (NTM), is rarely implicated in FIA and is more commonly associated with respiratory and skin infections. A man in his mid 30s with recurrent complex FIA underwent multiple surgeries over four years. Imaging and surgical exploration revealed a left ischiorectal collection and a sinus tract extending to the supralevator space. Tissue cultures grew M. abscessus subspecies massiliense, and histology showed non-necrotising granulomatous inflammation. The patient was a regular bidet user; this was considered the plausible source of inoculation given the organism's presence in water. He was treated with combination antimicrobial therapy comprising concurrent long-term oral azithromycin and clofazimine with an overlapping intravenous regimen including amikacin and imipenem resulting in clinical and radiological resolution. Environmental NTM exposure may underlie refractory FIA. Early recognition and targeted antimicrobial therapy are essential to avoid repeated surgery and prolonged morbidity.