Exserohilum keratitis: Clinical profile of nine patients and comparison of morphology versus ITS-Based DNA sequencing for species identification of the fungal isolates.

PURPOSE

The objective of this study was to describe the microbiological and clinical features of nine cases of Exserohilum keratitis.

PATIENTS AND METHODS

Fungal isolates from corneal scrapings were identified based on macroscopic and microscopic characteristics of the colonies and DNA sequencing of ITS1-5.8S-ITS2 region in the rRNA gene. All patients were treated with topical and if required systemic antifungals. Therapeutic penetrating keratoplasty (TPK) was done in case of failed medical therapy.

RESULTS

Morphologically, all fungal isolates were Exserohilum rostratum except one Exserohilum mcginnisii. Based on the BLAST analysis, 6 isolates showed 100% similarity to Setosphaeria rostrata (CBS 112815) and E. mcginnisii (CBS 20308). The other three isolates were Setosphaeria holmii (CBS 128053), not reported earlier in fungal keratitis. Three patients were lost to follow-up and response to medical therapy was good (Healed scar - 4 patients). Two out of nine patients were advised TPK.

CONCLUSIONS

Diagnosis and clinical features of Exserohilum keratitis are akin to other dematiaceous keratitis. The two morphological species of E. mcginnisii and E. rostratum are indistinguishable from Setosphaeria rostratum at DNA sequence level, which justifies the retention of the latter nomenclature.