Experimental guinea pig ocular infection by Salmonella typhimurium

The clinical, microbiologic, and cytologic features of the guinea pig model of keratoconjunctivitis with enterobacteria, Salmonella typhimurium were elucidated. Guinea pig eyes were instilled with S. typhimurium and the eyes were studied by biomicroscopy, culture, cytology, pathology, and electron microscopy. All animals developed moderate to severe conjunctivitis that was present in 18% of the animals on day 1. It became more intense, appearing in all of the eyes on day 10 and disappeared before day 30. The cultures for S. typhimurium were almost all positive on days 1 and 2, declined steadily to 10% on day 10, and were negative after that. A coarse, epithelial punctate keratitis was present in more than 90% of the infected eyes at some time during the experiment. The keratitis had a biphasic clinical course. The first peak correlated with the maximum culture results, but during the second peak only 10% of the cultures were positive. Electron microscopy of the cornea showed the S. typhimurium at the epithelial surface within surface epithelial cells during the early phases of infection. The later phase keratitis, with negative culture results, resembles the keratitis of Reiter's syndrome.