Abstract
Attempts to classify certain paradysentery-like bacteria have indicated a possible antigenic relationship between Shigella dispar and Shigella paradysenteriae, type P143. 1 In particular, a culture (No. 2-193) isolated by Major William H. Ewing, Sanitary Corps, United States Army, has been classified on various grounds as Sh. Paradysenteriae, type P143, 2 Sh. Alkalescens, 3 , 4 and Sh. dispar. 2 The present investigation was undertaken to attempt to clarify the relationship between Sh. dispar and type P143.
Four serotypes and several subtypes of Sh. dispar were previously reported. 5 Representative strains of these were employed. Type P143 was secured through the courtesy of Dr. K. M. Wheeler of the Connecticut Public Health Laboratories as his culture No. 573. 6 Antiserums were prepared by immunizing rabbits with living vaccines of this and of the type and subtype strains of Sh. dispar.
Cross agglutination tests indicated the existence of antigens common to type P143 and Sh. dispar, types I and II. This was confirmed by reciprocal adsorption of the cross-reacting serums, as shown in Table I. From these data were derived the partial antigenic formulae listed in Table II. The relationship between Sh. dispar, types I and II, and Sh. paradysenteriae, type P143, is apparent. While antigens B, C and D are apparently minor factors in P143, nevertheless, they appear to account for the strong agglutination (to titers of 1280 or 2560) of types I and II in antiserum PI43.
Culture 2-193 is biochemically like Sh. alkalescens.
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