Differentiation by Cataphoretic Velocity of Fresh and Old Laboratory Strains of H. Pertussis. ∗

In connection with studies concerned with the etiology of whooping cough we have examined the serological character of H. pertussis. Krumwiede, Mishulow, and Oldenbusch 1 have described 2 fixed serological varieties which they have designated as types A and B. Very recently Leslie and Gardner 2 have restudied the problem and have concluded that H. pertussis is a uniform species without fixed varieties or types when first isolated from the human subject, but that after subculture upon various laboratory media, it passes through a series of antigenically distinct phases which they have called Phases I, II, III, and IV. They believe the first 2 phases correspond to the smooth, and the last 2 to the rough varieties of other bacteria.

We have isolated H. Pertussis from early typical cases of whooping cough by the cough plate method and have studied 16 such fresh strains. In addition we have made observations on various old stock strains kindly provided us by Dr. Park in New York and Dr. Wads worth in Albany. We have confirmed the observations of Leslie and Gardner to the extent that we have been able by agglutinative, absorptive, and toxicity studies to demonstrate the uniformity of all fresh strains obtained by us in Cleveland and to show that they pass into antigenically different phases upon continued subculture. The determination of the toxicity of strains has been made upon rabbits by the skin test method using filtrates of the organism rather than by the use of guinea pigs as carried out by Leslie and Gardner. We have not been able to divide the later phases into the 3 sharp categories described by these authors. We are still working upon this aspect of the problem.