Serological identification of Shigella flexneri strains by the coagglutination reaction.

Several variants of reagents were prepared by coupling type (I, II III, IV, V and VI) and group (3, 4, 6 and 7, 8, 9) anti-Shigella flexneri sera with protein A--containing staphylococcal suspension. For most serum lots coagglutination led to a 1/10 minimum dilution. However, different efficiencies were reported between serum lots and even within the same type or group. No improvement by the coagglutination reaction could be obtained for one lot from group 3, 4 and 7, 8, 9 sera and for both type IV serum lots. The coagglutination reactions were specific both with collection strains and with recently isolated strains and the two staphylococcal suspension lots showed an identical behaviour. Coagglutination may be used for obtaining a better efficiency of type and group. Shigella flexneri sera but this varies in terms of the serum lot and the serum/Staphylococcus combination used.