Nontubercular mycobacteria (NTM) in fistula-in-ano: A new finding and its implications.

OBJECTIVE/BACKGROUND: Nontubercular mycobacteria (NTM) is not known to be associated with fistula-in-ano.

METHODS: A total of 311 consecutive fistula-in-ano patients operated on over 2years were analyzed. The histopathology of fistula-in-ano tract lining was performed in all the cases and other tests [real-time polymerase chain-reaction (RT-PCR), Gene Xpert, mycobacterial culture] were completed in patients with a high index of suspicion of having mycobacterial disease.

RESULTS: Two patients had histopathological features suggestive of mycobacterial disease. Out of these, one patient had NTM and another had mycobacterium tuberculosis (MTB) on RT-PCR. Four patients had normal histopathology features but tested positive on RT-PCR (two for NTM and two for MTB). Therefore, a total of six patients tested for mycobacterial disease (three for NTM and three for MTB). Mycobacterium culture was studied in two patients (both NTM) but was negative. Five out of six patients (two NTM and three MTB) presented with delayed recurrences after operations (6-18months after complete healing).

CONCLUSION: Nontubercular mycobacteria can cause fistula-in-ano. It could be an undiagnosed contributory factor in fistula recurrence. Mycobacterial disease (both tubercular and nontubercular) may be associated with delayed recurrence of fistula. RT-PCR is a highly sensitive test and can differentiate between NTM and MTB. It should perhaps be performed in all recurrent and refractory cases.