Epidemiological and microbiological diagnosis of suppurative keratitis in Gangetic West Bengal, eastern India

To determine the epidemiological pattern and risk factors involved in suppurative corneal ulceration in Gangetic West Bengal, eastern India, and to identify the specific microbial agents responsible for corneal infections.

All patients with suspected microbial keratitis presenting to the corneal clinic at Disha Eye Hospital, Barrackpore, West Bengal, India, from January 2001 to December 2003 were evaluated. Sociodemographic data and information pertaining to the risk factors were recorded. After diagnosing infective corneal ulcer clinically, corneal scraping and cultures were performed.

Over a three-year period, 1198 patients with suppurative keratitis were evaluated. Ocular trauma was the most common predisposing factor in 994 (82.9%) patients (P< 0.0001), followed by use of topical corticosteroids in 231 (19.28%) patients. Cultures were positive in 811 (67.7%) patients. Among these culture positive cases, 509 (62.7%) patients had pure fungal infections (P< 0.001), 184 (22.7%) patients had pure bacterial infections and 114 (14.1%) had mixed fungal with bacterial infections. Acanthamoeba was detected in 4 (0.49%) patients. The most common fungal pathogen was Aspergillus spp representing 373 (59.8%) of all positive fungal cultures (P< 0.0001), followed by Fusarium spp in 132 (21.2%) instances. Most common bacterial isolate was Staphylococcus aureus, representing 127 (42.6%) of all the bacterial culture (P< 0.0001) followed by Pseudomonas spp 63 (21.1%).

Suppurative keratitis in Gangetic West Bengal, most often occurs after a superficial corneal trauma with vegetative or organic materials. Fungal ulcers are more common than bacterial ulcers. Aspergillus spp and Staphylococcus aureus were the most common fungus and bacteria respectively. These "regional" findings have important public health implications for the treatment and prevention of suppurative corneal ulceration in this region of India.