Polymerase Chain Reaction versus Conventional Laboratory

To compare the value of conventional laboratory methods and polymerase chain reaction (PCR) in the diagnosis of fungal keratitis.

This cross sectional study was conducted at Khalili Hospital, Shiraz, Iran. Samples were taken from thirty-eight patients with findings suspicious for fungal keratitis. Corneal scrapings were used for Gram, Giemsa and KOH stains, culture and PCR analysis.

Of 38 enrolled eyes, 25 eyes (68.5%) were judged to have fungal infection based on positive cultures, staining, PCR or response to antifungal treatment. PCR detected fungi DNA in 17 of 25 samples (68% sensitivity). Staining (Gram, Giemsa and KOH) and culture yielded a positive result in 40% and 24% of samples respectively. Twenty one (84%) of 25 patients showed fungal elements in at least one laboratorywork up and 4 patients were diagnosed as fungal keratitis only based on response to antifungal drugs.

Compared to conventional laboratory methods, PCR based methods offer higher sensitivity and a faster diagnosis in fungal keratitis.