Corneal biopsy with tissue micro-homogenisation for isolation of organisms in bacterial keratitis.
OBJECTIVE
To evaluate a novel two-stage technique to increase yield of bacteria isolated from infected corneal ulcers.


METHODS
A new blade was designed to remove friable material from infected corneal ulcers. The new blade was used in combination with standard tissue micro-homogenisation equipment in a two-stage technique intended to distribute biopsy samples evenly between relevant agar plates. Patients with presumed-bacterial corneal ulcers underwent sequential corneal sampling using the new two-stage technique and a scalpel blade, used without micro-homogenisation (the order of sampling was varied between two groups). Bacterial isolation rates were compared using the chi-squared test.


RESULTS
Twenty-four patients with presumed-bacterial corneal ulcers were studied. The overall positive bacterial isolation rate was 88%, with identical bacterial isolation rates for the new two-stage technique and the scalpel blade (71%). The new technique isolated bacteria from three ulcers that had initially been 'sterile' when sampled with a scalpel blade. Polymicrobial infections were identified in two ulcers with the new blade where only a single organism had been identified using the scalpel blade (not significantly different).


CONCLUSIONS
The new two-stage technique shows promise for improving bacterial isolation rates from presumed-bacterial corneal ulcers.
Diamond
J
J
Bristol Eye Hospital, UK. j.p.diamond@bris.ac.uk
Leeming
J
J
Coombs
G
G
Pearman
J
J
Sharma
A
A
Illingworth
C
C
Crawford
G
G
Easty
D
D
D001419:Bacteria / Q000302:isolation & purification*; D001424:Bacterial Infections / Q000175:diagnosis*; D001431:Bacteriological Techniques / Q000295:instrumentation; D001706:Biopsy / Q000295:instrumentation / Q000379:methods; D003315:Cornea / Q000382:microbiology*; D003320:Corneal Ulcer / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male