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Mycotic keratitis among sugarcane farmers caused by Fusarium Sacchari

July 11 2016

Mycotic keratitis is an inflammation of the cornea, as a result of infection with yeast or filamentous fungi. Risk factors include ocular trauma, contact lenses, prolonged use of topical steroids, diabetes and pre-existing ocular diseases.

Two of the most common causes of mycotic keratitis are Aspergillus and Fusarium spp., a hyaline filamentous fungi capable of causing superficial infections or more serious, disseminated infections in immunocompromised patients. Fusarium sacchari is one of  11 clinically relevant species grouped under the Fusarium fujikoroi species complex. It was first identified from sugarcane in India and it is widely distributed in sugarcane areas in Asia. There have only been a few case reports of this species causing human infections. Out of 125 patients with suspected keratitis in an outpatient ophthalmology department, 14 were diagnosed with an infection caused by Fusarium spp. Yashik Bansal and colleagues (Department of Microbiology in the Government Medical College Hospital, India) report on four cases caused by Fusarium sacchari in sugarcane farmers in India.

Aspergillus keratitis - Severe Aspergillus infection with large area of corneal ulceration and deep stromal involvement.

Two male and two female patients from Haryana presented with pain, redness and decreased vision after trauma with sugarcane leaf, or vegetative matter while working on a sugarcane farm. In each case, LCB mount preparation of the growth obtained on Sabouraud dextrose agar (SDA) showed the characteristic banana-shaped macroconidia of the genus Fusarium, therefore providing a diagnosis of fusarial keratitis. Microscopic examination is able to identify the causative fungus up to genus level, but species level identification requires molecular methods. The final species identification was therefore carried out by genetic sequencing at CBS-KNAW, Utrecht. All patients received antifungal therapy with topical voriconazole, some received additional treatment, including therapeutic penetrating keratoplasty, oral itraconazole, natamycin and topical amphotericin B.

The incidence of F. sacchari keratitis reported here is higher than previous reports. This may be due to the region studied (sugarcane  region) and full identification of the species using molecular identification. methods .Fusarium spp. shows very high resistance to most antifungals; however the patients in this study all responded well to treatment