الفهرس 
CORNEAL ULCERSOnly 14 pages are availabe for public view
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Abstract
F
ungal keratitis is a leading cause of serious ocular morbidity and blindness. It is worldwide in distribution, but is more common in the tropics and subtropical regions. The incidence of fungal keratitis in Egypt is 20-55% and it is increasing.
Various factors are implicated in increased incidence of fungal keratitis including widespread use of antibiotics and steroids, use of contact lenses, ocular trauma with agricultural materials, systemic immunosuppression, diabetes and postoperative infection.
Fusarium and Aspergillus are the most important causes of fungal keratitis that has been recognized in industrialized countries, especially in hot and humid areas.
The diagnosis of fungal keratitis continues to be problematic. Many clinical characteristics are not specific to fungal ulcers; therefore, antifungal therapy should be withheld until a diagnosis is confirmed by laboratory studies.
The gold standard of laboratory diagnosis is still the routine microbiological method including microscopic examination and culture. Direct microscopic examination of a corneal scraping sample provides great information for immediate diagnosis.
Treatment remains limited by the scarcity of effective antifungal drugs and the serious resistance of some pathogens. Therefore, establishing a rapid specific method to diagnose fungal keratitis, as well as understanding the etiological and epidemiological characteristics of it, is significant for early diagnosis, effective treatment and prognosis after recovery.
This study aims to measure the value of Calcofluor white (CFW) stain for the rapid detection of fungal keratitis and to compare the positive rates, sensitivity and specificity with those of a 10% Potassium hydroxide (KOH)-based smears and culture technique.
During this study, thirty corneal scraping samples were collected from patients attending ophthalmology outpatient clinics in Ain Shams University Hospitals were included. They were subjected to 10% KOH wet mount examination, Calcofluor white stain examination and cultivation on Blood agar and Sabouraud dextrose agar in C-shaped manner.
Eleven 11/30 (36.7%) cases were diagnosed as fungal keratitis, thirteen 13/30 (43.3%) cases were diagnosed as bacterial keratitis and the remaining six 6/30 (20%) cases showed no growth.
Fusarium was the most common fungal isolate (36.4%), followed by Aspergillus spp (27.3%) while Staphylococcus aureus was the most common bacterial isolate (46.2%) followed by Pseudomonas (38.4%).
10% KOH wet mount examination showed a sensitivity, specificity, PPV, NPV and accuracy of 72.7%, 100%, 100%, 86.4% and 90% respectively compared to culture on SDA.
Calcofluor white stain showed a sensitivity, specificity, PPV, NPV and accuracy 90.9%, 100%, 100%, 95% and 96.7% respectively compared to culture on SDA.
Calcofluor white stain is a rapid true positive test to diagnose fungal keratitis and it is the most sensitive method and superior to 10% KOH wet mount when using direct microscopy examination.
Although culture helps in definite diagnosis and identification, direct microscopic detection of fungal structures in corneal scrapings permits a rapid presumptive diagnosis.
CONCLUSION AND RECOMMENDATIONS
T
he following are the conclusions derived from the present study:
• A variety of fungal isolates can cause infectious corneal ulceration.
• Among the various predisposing factors, trauma in farm workers plays a major role in producing corneal ulceration with seasonal variation.
• Microscopy and culture (gold standard) should be the dictum for every case of corneal ulcer investigation in the laboratory.
• Precise identification of the causative organisms and timely institution of appropriate antifungal therapy based on the prevailing sensitivity pattern of the fungal isolates could save the eye from this preventable cause of blindness which was carried out by Media education and audio visual aids to create public awareness regarding vision and vulnerability to infection.
• Calcofluor white stain is a rapid true positive test to diagnose fungal keratitis and it is the most sensitive method and superior to 10% KOH wet mount when using direct microscopy examination.
• The microbiological profile helps the ophthalmologists to start the specific treatment directed against the causative organisms as corneal ulcer is a medical emergency.
Therefore, we strongly recommend the following:
• The diagnosis of fungal keratitis must be confirmed prior to initiating the antifungal treatment.
• Using Calcofluor white stain as a rapid, simple and sensitive method for early diagnosis of fungal keratitis.
• Further studies on the using of polymerase chain reaction (PCR) in the diagnosis of fungal keratitis are recommended to be compared with direct microscopy as a rapid and sensitive method.
• Further studies, like in vivo fluorescent imaging technology are recommended to be compared with direct microscopy as it is a noninvasive and rapid procedure.
• Further studies on broad scales with large sample size are recommended to evaluate the value of calcofluor white stain in the rapid diagnosis of fungal keratitis.