Classification of Vibrio cholerae (Vibrio comma), Including El Tor Vibrios, by Infrasubspecific Characteristics

Feeley, John C. (National Institutes of Health, Bethesda, Md.). Classification of Vibrio cholerae (Vibrio comma), including El Tor vibrios, by infrasubspecific characteristics. J. Bacteriol. 89:665–670. 1965.—A study of the properties of 220 serotype O group I vibrios indicated striking similarity in most of their properties. However, by using four tests often applied in the identification of the El Tor vibrio, five types were identified and characterized as follows: type 1 strains, phage IV-sensitive, nonhemolytic by tube and plate methods, unable to agglutinate chicken red cells (CCA), and Voges-Proskauer (VP) negative or weakly positive at 22 C; type 2, same as type 1 except for CCA; type 3, phage IV-resistant, CCA and VP usually positive, and strongly hemolytic by tube and plate methods; type 4, same as type 3, except hemolytic only by plate method unless culture has undergone pronounced rugose variation; and Type 5, same as type 3, except stably nonhemolytic. Type 1 and type 3 strains possess the characteristics usually ascribed to classic cholera vibrios and El Tor vibrios, respectively. Geographical and chronological distribution of the types is discussed. The thesis is presented that it is invalid to recognize two species, V. cholerae and V. eltor, because alleged differences are infrasubspecific. Recognition of a single species, V. cholerae, consisting of several types, is recommended.