Taxonomic Relationships in the Genus Proteus

Recently Cope and Kilander 1 described 83 strains isolated from gastroenteritis patients, contacts and foodhandlers with suggestive or definite history of enteric disorders as “atypical enteric organisms of the Shigella group.” Stuart et al. 2 reported 19 comparable strains tentatively classed as “anaerogenic paracolon” cultures which were isolated in this laboratory or received from the laboratories of several states. To date the number of strains studied by us has increased to 48, including 5 strains kindly furnished by Dr. E. J. Cope. Forty-three of the strains were isolated from fecal specimens of gastroenteritis patients or foodhandlers, one from the blood of a patient and 4 from apparently normal contacts. To facilitate discussion the cultures studied in this laboratory will be called, type 33111. Cultural Characteristics. Type 33111 cultures grew readily on eosin methylene blue agar and on Salmonella Shigella agar forming transparent and colorless colonies. All strains isolated in this laboratory were motile in semisolid, tryptone agar (0.25% agar) at 25 °C. Several strains received from different laboratories as nonmotile on isolation were motile under the conditions specified. The motility of type 33111 cultures was usually poor and sometimes negative at 37°C. On agar slants an occasional strain showed slight spreading. On nutrient agar lates (1.0% agar) inoculated by touching the center of the plate with a needle, the growth of some strains covered the entire surface of the plate, others partially, others spread slightly while a few showed no tendency to spread after 48 hours at 25°C. The swarming characteristic of some strains was suggestive of the genus Proteus and flagella stains were made on representative strains of each species in this genus. Pr. vulgaris, Pr. mirabilis, Pr. morganii and type 33111 cultures showed peritrichous flagellation.