Fungal Keratitis

Microbiological Culture

Fungal keratitis is best diagnosed using gram culture. Corneal scrapes are taken and cultured with both selective and non-selective media. Blood agar as well as Sabouraud dextrose agar serve as common mediums. Macroscopic and microscopic examination of fungal growth confirms infection. Extraction facilitates the identification of the pathogen, permitting antifungal therapy to be tailored based on susceptibility testing.

Molecular Techniques

The diagnosis of fungal keratitis has been transformed profoundly with the introduction of rapid and ultra-sensitive detection of fungal DNA using polymerase chain reaction (PCR). Unlike culturing which takes days, PCR can identify specific fungal species within hours. This method is especially useful when culture results are negative but there is a strong clinical suspicion. Unfortunately, PCR does not allow antifungal susceptibility testing, and contamination resulting in false positive results need to be carefully controlled.

Direct Microscopy

Direct microscopy like the use of Gram stain, Giemsa stain, KOH, and KOH wet mounts are rapid methods for detecting fungal elements in corneal scraping. KOH wet mount is particularly useful in the visualization of hyphal and yeast forms of fungi. The sensitivity of direct microscopy is aided by the use of additional stains such as trypan blue which aid in staining fungal filaments thereby improving the visualization.

Artificial Intelligence

The advancement of technology has greatly aided in the AI diagnosis of fungal keratitis. Today, AI algorithms analyze clinical data alongside slit-lamp photographs and confocal microscope images, distinguishing fungal keratitis from other infections. In addition, these algorithms predict therapeutic outcomes enabling them to tailor therapeutics, therefore increasing the precision and efficacy of clinical decisions.