A Simple Presumptive Test for Toxigenicity of Corynebacteria

Abstract

The cultures to be tested are inoculated on the chorio-allantoic membrane of 9- to 10-day-old embryonated hen''s eggs, after purification by a process descr. After injn. of 0.05 ml. under the otherwise unbroken shell membrane, the latter is then painted with a sterile, melted paraffin-vaseline mixture and the eggs incubated at 37[degree]C. 99% of 444 embryos inoculated with toxigenic strains with Corynebacterium diptheriae were dead in 96 hrs. under the above conditions; 84% of 84 embryos tested with non-toxigenic strains were alive at 96 hrs. 32 strains were tested by this method, 9 being known C. diphtheriae and 23 having been isolated from cases of clinical or suspected diphtheria. Toxigenicity, as detd. in guinea pigs, corresponded exactly with the results in the embryos. Death of 80% or more of the embryos in test lots of 10 or more for each culture may be regarded as a specific indication of toxigenicity, and the method is especially valuable in laboratories not having provisions for care and maintenance of animals.