Microbial Keratitis in Nepal: Predicting the Microbial Aetiology from Clinical Features

Area of Science:

• Ophthalmology
• Medical Mycology
• Infectious Diseases

Background:

• Fungal corneal infection (keratitis) presents diagnostic challenges in South Asia, often mimicking bacterial or acanthamoeba infections.
• Accurate and timely etiological diagnosis is crucial for effective management of microbial keratitis.

Purpose of the Study:

• To identify clinical and epidemiological features predicting the etiology of microbial keratitis in Nepal.
• To develop a predictor score for fungal keratitis based on identified clinical signs.

Main Methods:

• Prospective study involving patients with keratitis at a tertiary eye hospital in Nepal.
• Data collection included demographics, history, clinical signs, in vivo confocal microscopy, and corneal scrapings for microscopy and culture.
• Odds ratios were calculated to develop a predictor score for etiological diagnosis.

Main Results:

• Fungal keratitis accounted for 75.1% of cases (82.9% including mixed infections).
• Dematiaceous fungi, particularly Curvularia spp., were unusually prevalent, causing 50.6% of culture-positive fungal cases.
• Serrated infiltrate margins, patent nasolacrimal duct, raised corneal slough, and organic trauma were independently associated with fungal keratitis (p < 0.01).
• A predictor score combining these features showed increasing probability of fungal keratitis from 30.1% (one feature) to 96.3% (all four features).

Conclusions:

• Certain clinical signs can effectively predict fungal keratitis, aiding presumptive diagnosis and prompt treatment initiation.
• Dematiaceous fungi, specifically Curvularia spp., are identified as a major cause of fungal keratitis in this region.
• Further research is warranted to explore the implications and temporal trends of dematiaceous fungal infections in Nepal.