title: Corneal biopsy with tissue micro-homogenisation for isolation of organisms in bacterial keratitis.
abstract: 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.
authors.affiliation: Bristol Eye Hospital, UK. j.p.diamond@bris.ac.uk
authors.forename: J
authors.initials: J
authors.lastname: Diamond
authors.forename: J
authors.initials: J
authors.lastname: Leeming
authors.forename: G
authors.initials: G
authors.lastname: Coombs
authors.forename: J
authors.initials: J
authors.lastname: Pearman
authors.forename: A
authors.initials: A
authors.lastname: Sharma
authors.forename: C
authors.initials: C
authors.lastname: Illingworth
authors.forename: G
authors.initials: G
authors.lastname: Crawford
authors.forename: D
authors.initials: D
authors.lastname: Easty
mesh_terms: 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