Fungal keratitis in patients with corneal ulcer in Sari, Northern Iran.Arch Iran Med 2006; 9(3):222-7AI
Fungal keratitis is a suppurative, ulcerative, and sight-threatening infection of the cornea that sometimes leads to loss of the eye. The objectives of this study were to improve facilities for laboratory diagnosis, to determine the predominant causative microorganisms, and to identify the predisposing factors of mycotic keratitis patients.
A prospective study of corneal ulcer was conducted in Sari between May 2004 and March 2005. Patients who presented with clinically suspected corneal ulcer to the Ophthalmology Department of Bou-Ali Sina University Hospital in Sari were included in this study. Each patient was examined with slit lamp. Data were collected by examining and questioning the patients. Using standard techniques, corneal scraping was performed by an ophthalmologist. The specimens collected were then smeared on two slides, which were stained with Gram stain (for bacterial keratitis) and 10% potassium hydroxide with or without Calcofluor white stain (for fungal keratitis), and studied under light microscope. The specimens were also inoculated directly on blood agar, Sabouraud dextrose agar, and potato dextrose agar in C-shaped streaks.
A total of 22 patients met the inclusion criteria of this study, among whom 10 (45.5%) were females and 12 (54.5%) were males. The mean +/- SD age of patients was 61.5 +/- 17.7 (range: 15 - 83) years. In direct microscopy, branching, and septate hyphae were identified in 7 (31.8%) patients. Two (28.6%) fungi (Aspergillus fumigatus and Fusarium spp.) were isolated. Five (31.8%) patients with fungal keratitis were males and 2 (28.6%) were females. The mean +/- SD age of patients with fungal keratitis was 60.4 +/- 12.1 (range: 39 - 73) years. Three (42.85%) patients with fungal keratitis were farmers. The mean interval between the onset of symptom and diagnosis was 26.4 (range: 1 - 93) days. Trauma with plant debris and straws were noted in two (28.6%) patients with fungal keratitis. Five (71.4%) patients received topical antibiotics. Analyses, using potassium hydroxide with or without Calcofluor white as the gold-standard test, revealed a sensitivity of 71.4% for potassium hydroxide, and 42.9% for Gram stain.
Infections of the cornea due to filamentous fungi are frequent causes of corneal damage and should always be kept in mind. The direct microscopy method is an essential tool in the diagnosis of fungal keratitis. Therefore, wet mount preparation with potassium hydroxide with or without Calcofluor white or only KOH can be relied upon as the single most important screening test for rapid diagnosis of fungal corneal ulcer.