Corneal biopsy with tissue micro-homogenisation for isolation of organismsin bacterial keratitis

Purpose To evaluate a novel two-stage technique to increase yield of bacter ia isolated from infected corneal ulcers. Methods A new blade was designed to remove friable material from infected c orneal ulcers. The new blade was used in combination with standard tissue m icro-homogenisation equipment in a two-stage technique intended to distribu te biopsy samples evenly between relevant agar plates. Patients with presum ed-bacterial corneal ulcers underwent sequential corneal sampling using the new two-stage technique and a scalpel blade, used without micro-homogenisa tion (the order of sampling was varied between two groups). Bacterial isola tion rates were compared using the chi-squared test. Results Twenty-four patients with presumed-bacterial conceal ulcers were st udied. The overall positive bacterial isolation rate was 88%, with identica l bacterial isolation rates for the new two-stage technique and the scalpel blade (71%). The new technique isolated bacteria from three ulcers that ha d initially been 'sterile' when sampled with a scalpel blade. Polymicrobial infections were identified in two ulcers with the new blade where only a s ingle organism had been identified using the scalpel blade (not significant ly different). Conclusions The new two-stage technique shows promise for improving bacteri al isolation rates from presumed-bacterial corneal ulcers.