Comparison of techniques for culturing corneal ulcers

Ophthalmology. 1992 May;99(5):800-4. doi: 10.1016/s0161-6420(92)31897-4.

Abstract

All consecutive cases of presumed microbial keratitis were cultured with both a platinum spatula and calcium alginate swab moistened with trypticase soy broth. Ten (77%) of the 13 culture-proven ulcers in this series showed a greater number of colonies and more confluent growth on the agar plates inoculated with a moistened swab compared with a much lower yield obtained using a platinum spatula. All culture-positive bacterial ulcers showed growth when cultured with a swab. Two ulcers that were partially treated before culturing yielded very light growth from those rows inoculated with a swab and no growth from those rows inoculated with a spatula. Two ulcers showed equal growth between the two methods. One ulcer (Actinomycetes-Streptomyces/Nocardia) had greater growth obtained with a spatula compared with a swab. This series demonstrated a significantly greater retrieval of organisms from bacterial keratitis when a calcium alginate swab moistened with trypticase soy broth was used to rub the ulcer and directly inoculate the solid agar media. The single case of filamentous bacteria suggests that a spatula may yield better organism retrieval from ulcers caused by filamentous organisms.

Publication types

  • Comparative Study

MeSH terms

  • Bacteria / growth & development
  • Bacteria / isolation & purification*
  • Bacteriological Techniques*
  • Colony Count, Microbial
  • Corneal Ulcer / microbiology*
  • Culture Media
  • Eye Infections, Bacterial / microbiology*
  • Humans

Substances

  • Culture Media