Nontuberculous mycobacteria in fistula-in-ano: A new finding and its implications

Objective/background: Nontuberculous mycobacteria (NTM) are not known to be associated with fistula-in-ano. NTM was detected in three fistula-in-ano patients in our series. In this study, related data was reviewed to find the mycobacterial disease in patients in our database. Methods: In this study, 311 consecutive fistula-in-ano patients operated over 2 years were analyzed. The histopathology of anal fistula tract epithelial lining of every operated patient was analyzed and other tests (real-time-polymerase chain reaction [RT-PCR], GeneXpert, and mycobacterial culture) were conducted in patients with high index of suspicion of having mycobacterial disease. Results: Two patients had histopathological features suggestive of mycobacterial disease. Of these, one patient had NTM and the other had Mycobacterium tuberculosis (MTB) on RT-PCR. Four patients had normal histopathology features but tested positive on RT-PCR (2 each for NTM and MTB). Therefore, a total of six patients were tested for mycobacterial disease (3 each for NTM and MTB). Mycobacterium culture was performed in two patients (both NTM) but the result was negative. Five of six patients (NTM = 2, MTB = 3) presented with delayed recurrences after operation (6-18 months after complete healing). Conclusion: NTM can cause fistula-in-ano. It could be an undiagnosed contributory factor in fistula recurrence. Mycobacterial disease (both tuberculous and nontuberculous) may be associated with delayed recurrence of fistula. RT-PCR is highly sensitive and can differentiate between NTM and MTB. It should perhaps be performed in all recurrent and refractory cases.