A case of fungal otitis externa caused by coinfection of Candida auris and Aspergillus flavus

Fungal otitis externa is a disease encountered occasionally and is caused mostly by Aspergillus or Candida spp. We report a woman with fungal otitis externa who also had typical findings in the external auditory canal. The results of a culture showed coinfection with Candida auris and Aspergillus flavus. Identification of both species was performed by sequencing analysis of the 26S rDNA (D1/D2) and β-tubulin regions. Additionally, the newly developed CHROMagar™ Candida Plus medium was a useful tool for the easy and rapid identification of C. auris. To the best of our knowledge, this is the first report of fungal otitis externa caused by coinfection with C. auris and A. flavus. This case showed good susceptibility to many antifungal drugs and fortunately had a good clinical course with 1% bifonazole cream, which was applied to the fungal coinfection. Notably, C. auris is a multidrug-resistant yeast-like fungus. The increase in drug-resistant fungi and co-infections caused by these pathogens can make the diagnosis and treatment more complex and difficult. To solve these problems, performing rapid and accurate identification and susceptibility testing using chromogenic medium and molecular biological analysis would be useful.