The characteristics of keratomycosis by Beauveria bassiana and its successful treatment with antimycotic agents

Hiroko Sonoyama¹, Kaoru Araki-Sasaki¹, Shigeyasu Kazama¹, Tsutomu Kawasaki¹, Hidenao Ideta¹, Atsuko Sunada², Seishi Asari², Yoshitsugu Inoue³, Kozaburo Hayashi⁴

¹Ideta Eye Hospital, Kumamoto, Kumamoto, Japan; ²Department of Laboratory for Clinical Investigation, Osaka University Hospital, Suita, Osaka, Japan; ³Division of Ophthalmology and Visual Science, Department of Medicine of Sensory and Motor Organ, Tottori University, Yonago, Tottori, Japan; ⁴Immunology and Virology Section Lab, Immunology, NEI, NIH, Bethesda, MD, USA

Abstract: Clinical findings and treatment of keratomycosis caused by Beauveria bassiana, an entomopathogenic filamentous fungus, are described for an 80-year-old woman, who was referred to the hospital for ocular pain and redness on the 9th day after an ocular injury caused by the frame of her glasses. She had a long history of recurrent diabetic iritis and continuously used topical antibiotics and corticosteroids. At her first visit, a slit-lamp examination indicated a corneal ulcer confined within the superficial stromal layer, along with a slight infiltration and edema. Only a very few inflammatory cells were seen in the anterior chamber. Direct microscopic examination of corneal scrapings revealed septate fungal hyphae with zig-zag rachis and budding that was subsequently identified as B. bassiana by slide culture. Topical voriconazole with miconazole, pimaricin and oral itraconazole were effective and the lesion disappeared leaving only a mild scar at 2 months. The sensitivity of B. bassiana to various antimycotic agents was confirmed by broth microdilution, agar dilution with the Clinical Laboratory Standard Institute standard, and a disk method using topically applied concentrations. B. bassiana, which exhibits a characteristic appearance in smears and causes superficial keratomycosis, is sensitive to voriconazole with miconazole, pimaricin, and itraconazole.

Keywords: Beauveria bassiana, keratomycosis, filamentous fungus, voriconazole, corneal infection