This paper reports the isolation of strains of elementary bodies from trachoma cases in Saudi Arabia and Egypt by inoculation of the yolk sacs of chick embryos. Nineteen strains were obtained in 45 attempts using conjunctival scrapings from children who were shown to have typical inclusions at the time of the scraping. Nine of the strains were subjected to a series of tests which showed that they were indistinguishable morphologically from the elementary bodies of the psittacosis-lymphogranuloma group of viruses, that they were not sensitive to streptomycin, that they were free of other viruses and of pleuropneumonia-like organisms, that they were toxic for white mice by the intravenous route, and that they contained the heat stable antigen which is common to the psittacosislymphogranuloma group of viruses. Although each strain was capable of multiplication in yolk sac membranes of chick embryos, irregularities of growth were frequently observed, being more characteristic of certain strains, than others.
Viability of the trachoma elementary bodies in conjunctival scrapings persisted at -60°C for many months if the specimens were stored in a medium containing sucrose, glutamate, and phosphate. One of the strains induced conjunctivitis in a chimpanzee whose conjunctival cells showed typical inclusions at the height of the conjunctival reaction. A laboratory worker contracted severe trachoma probably as a consequence of air-borne droplets arising from manipulations of concentrated suspensions of the elementary bodies.