Distal Lateral Subungual Onychomycosis Owing to Tritirachium oryzae: A Bystander or Invader?

The genus Tritirachium is a mitosporic fungus which inhabits in soil and decaying plant material and also a notable insect pathogen. Human infections with Tritirachium species though rare were previously reported to cause corneal ulcers, otomycosis, onychomycosis, and dermatomycosis of the scalp and hence may be considered as a potential pathogen. Here we report a case of distal lateral subungual onychomycosis involving right great toenail in a 22-year-old female, wherein direct potassium hydroxide preparations, fungal cultures, and molecular sequencing of the isolate established Tritirachium oryzae as the etiological agent. Antifungal susceptibility performed by the microbroth technique of CLSI revealed increased MICs to amphotericin B and low MICs to azoles and echinocandins. The case was managed with surgical nail avulsion followed by topical application of 2% ketoconazole cream resulting regrowth of normal nail. To the best of our knowledge, this is the first report of non-dermatophytic mold T. oryzae causing onychomycosis in India.