Changing Referral Patterns of Infectious Corneal Ulcers to a Tertiary Care Facility in South India – 7-year analysis

PURPOSE: To report changing trends in referral patterns of microbial keratitis evidenced by laboratory results of culture-positive cases from a tertiary eye-care hospital in south India. METHODS: All patients presenting with microbial (nonviral) keratitis to the cornea services of Aravind Eye Hospital from 2003 to 2009 were identified from a computerized database. Microbiologic characteristics were recorded and annual distributions of causative organisms over the 7-year study period were compared. RESULTS: Out of a total of 3059 cases of presumed microbial keratitis, 1756 had positive cultures (57.4%). Among the culture-positive cases, fungal pathogens were isolated from 1224 cases (70%), 488 (27.7%) showed bacterial growth, 18 (1.03%) grew acanthamoeba species and 26 (1.5%) demonstrated mixed bacterial and fungal growth. The percentage of fungal isolates in culture-positive cases increased gradually over the study period from 59% in 2004 to 78% in 2009. This increase in frequency of fungal keratitis was statistically significant (P = 0.023). A proportionally decreasing trend was seen in the number of bacterial isolates ranging from 31% in 2003-2005 to 22% in 2009 (P = 0.04). CONCLUSIONS: An incremental increase was seen in the number of fungal keratitis cases referred to our institute during the study period. Bacterial keratitis showed a decline. This disconcerting trend may lead to an increase in the incidence of corneal blindness in the developing world and thus warrants further research.