Detection of fungi by conventional metho ds and semi-nested PCR in patients with presumed fungal keratitis

Background and Purpose: Fungal keratitis is a suppurative, ulcerative, and sight-threatening infecti on of the cornea that sometimes leads to blindness. The aims of this study were: recuperating facilities for laboratory diagnosis, determining the causative microorganisms, and comparing conventional laboratory diagnostic tools and semi-nested PCR. Materials and Methods: Sampling was conducted in patients with suspected fungal keratitis. Two corneal scrapings specimens, one for direct smear and culture and the other for semi- nested PCR were obtained. Results: Of the 40 expected cases of mycotic keratitis, calcofluor white staining showed positivity in 25%, culture in 17.5%, KOH in 10%, and semi-nested PCR in 27.5%. The sensitivities of semi-nested PCR, KOH, and CFW were 57.1%, 28.5%, and 42% while the specificities were 78.7%, 94%, and 78.7%, respectively. The time taken for PCR assay was 4 to 8 hours, whereas positive f ungal cultures took at least 5 to 7 days. Conclusion: Due to the increasing incidence of fungal infections in people with weakened immune systems, uninformed using of topical co rticosteroids and improper use of contact lens , fast diagnosis and accurate treatment of keratomycosis seems to be essential . Therefore, according to the current study , molecular methods can detect mycotic keratitis early and correctly leading to appropriate treatment.