Different Immunological Types of B. Pertussis. 201 



being taken to have them free of vitamines. These hydrolysates 

 were tested on the growth of streptococci and yeast cells. The 

 bacterial growth was measured by the increase in the acidity of 

 the medium, by means of the Sorensen Indicator method. The 

 action on yeast was not constant, and in most cases showed a 

 growth inhibition due to the known inhibiting action of certain 

 amino acids. 



The results on streptococci, which are summarized in Table 

 III, strongly suggest that the growth-stimulating action of protein 

 hydrolysates is not due to a constituent part of the protein mole- 

 cule, but to a vitamine-like substance, probably similar to vita- 

 mine D, which is present as an impurity, and which cannot be 

 removed by the known methods of protein purification. 



93 (1840) 



The existence of different immunological types of B. pertussis. 



By CHARLES KRUMWIEDE and LUCY MISHULOW. 



[From the Bureau of Laboratories, Department of Health, 

 New York City.] 



Twenty-two strains having the typical morphological and 

 cultural characteristics of B. pertussis have been studied by means 

 of the agglutination and agglutinin absorption reactions. These 

 tests have demonstrated that the cultures studied fall into two 

 serological groups. If the two groups are tentatively designated 

 as "a" and u b" the results may be briefly described as follows: 

 Anti-serums for group u b" agglutinate the strains of group "b" 

 but agglutinate the strains of group "a" very slightly or not at 

 all. The absorption of group "b" serum by group "a" strains 

 does not appreciably reduce the agglutinins for group "b." 

 Group "a" serum, however, agglutinates group "b" strains to 

 a considerable extent. The absorption of group "a" serum by 

 group "b" strains results in a reduction of the agglutinins for 

 strain "a." The serological differences, therefore, are sharply 

 defined in one direction, but group relationship is shown in the 

 reverse direction. These findings are of immediate interest 

 because of their possible bearing on the use of pertussis vaccines. 



