Mannitol Negative Varieties of Shigella Flexneri Serotypes

Abstract

Summary The results of biochemical and serological studies with cultures of mannitol negative Shigella flexneri 1b, 2a, 3, and 4a are reported. The results indicated that the mannitol negative variety previously referred to as the Saigon bacillus, S. saigonensis, B. rabaulensis, S. rio, etc., are S. flexneri 4a cultures. Hence, no special epithet nor special subserotype designation is needed for cultures of this serotype. Mannitol negative varieties of S. flexneri 1b and 2a are described, apparently for the first time. It was clear that none of the mannitol negative S. flexneri varieties had claim to separate status in a system of classification and that they should be looked upon as variants of the parent types. Two types of modified form variation in S. flexneri cultures were studied and discussed. Form variation appeared to occur more frequently in S. flexneri 4a strains than in other S. flexneri serotypes. The literature on the subject of mannitol negative varieties of S. flexneri was reviewed.