Utilization and yield of the ocular microbiology laboratory in the diagnosis of visually threatening keratitis

Purpose. With the advent of readily available broad spectrum topical antibiotics, ophthalmologists may be less inclined to perform corneal smears and cultures. The purpose of this study is to investigate the diagnostic capability and utilization of a university-based ocular microbiology laboratory. Methods. A retrospective review was performed examining 164 consecutive corneal cultures performed on patients with visually threatening keratitis submitted to our ocular microbiology laboratory from October 1994 through October 1995. Results. Seventy-five isolates were obtained with 6% of eyes (10/164) yielding multiple organisms. 42% of cultures were positive (69/164). There were 52 bacterial organisms, 16 fungal organisms and 7 parasitic organisms recovered. All isolates were examined by our ocular microbiologist, who was able to correctly identify 12% (9/75) of organisms with gram and giemsa staining alone. Conclusions. The ocular microbiologist remains an important consultant for the proper diagnosis of visually threatening keratitis. The low diagnostic yield of gram and giemsa staining suggest that smears alone are not sufficient. As ophthalmologists, we should concentrate our efforts on better specimen collection and organism identification.