The effect of climatic and seasonal factors on the microbial keratitis profile

To compare retrospective data on microbial keratitis (MK) from two different climatic regions in Turkey over 11 years.

Retrospective cohort.

This retrospective cohort study included patients diagnosed with presumed MK at two referral centers. Center A was located in the subtropical region of Turkey, whereas Center B was located in a continental temperate climate zone. Clinical and laboratory data were also recorded. The results were evaluated for seasonal variations.

This study included data from 665 patients with presumed MK (351 and 314 patients from centers A and B, respectively). The most common predisposing factors were ocular trauma in Center A, prior ocular surgery, and systemic disease in Center B. Severe keratitis was related to prior ocular surgery, presence of systemic disease, and fungal infection at presentation. The culture positivity rate was higher in spring and lower in summer at both centers. Gram-positive bacteria were the most commonly isolated bacteria in both centers in all seasons. The fungal and mixed keratitis ratios were higher in Center A than in Center B. In Center A, filamentous fungi were common pathogens that were found year-round, and peaks were observed in July and October.

The results of this study show that climatic and seasonal factors may affect the microbial profile of keratitis. Fungal keratitis appears to be a climatic disease. Understanding the regional profile of MK can aid clinicians in their disease management.