Diagnostic limulus lysate assay for endophthalmitis and keratitis

J. McBeath, R. K. Forster and G. Rebell

The limulus lysate assay is an inexpensive, reliable, and rapid means of detecting and presence of Gram-negative endotoxin. In all ten cases of experimentally induced Proteus endophthalmitis in rabbits, the assay was positive, and the assay was appropriately negative in all ten cases of Staphylococcal endophthalmitis, ten cases of Candida endophthalmitis, and ten cases of sterile endophthalmitis in rabbits. In a clinical assessment of keratitis, the assay of corneal scrapings was positive in 11 of 13 Gram-negative corneal ulcers. In a similar study of clinical endophthalmitis, both Gram-negative cases had a negative limulus assay, but two cases are insufficient to be conclusive. The assay may prove to be a useful adjunct both to standard diagnostic evaluations and in the rapid direction of appropriate therapy for these conditions.