EXPERIMENTAL SHIGELLA INFECTIONS: CHARACTERISTICS OF A FATAL INFECTION PRODUCED IN GUINEA PIGS

Abstract

As long as man, the chimpanzee and the monkey are the only species in which enteric shigella infections can be studied, progress in problems concerning the pathogenesis of and im-munity to bacillary dysentery will be seriously hanmpered. In recent years, successful attempts have been made to modify small laboratory animals in such ways as to make them susceptible to orally administered enteric pathogens. Thus Freter (1955) and Lowenthal (1953, personal communication), working independently, em-ployed virtually identical methods to produce fatal infections in guinea pigs with orally ad-ministered cultures of Vibrio comma. The pro-cedure involved starving the animal for four days and administering calcium carbonate prior to, and opium following, oral challenge. To modify the normal intestinal flora further, Freter treated his animals with streptomycin and used a strep-tomycin-resistant culture for challenge. Lowen-thal found, however, that with the bacterial cultures and animals which he employed, treat-ment with streptomycin did not render the animals more susceptible. More recently Freter (1956) has described a long-term, nonfatal in-fection with either V. comma or Shigella flexneri 2a in guinea pigs which had been both (a) starved for 36 of the 48 hr prior to challenge, and (b) treated with antibiotics to alter the normal intestinal flora. No examination for intestinal lesions is mentioned in this report. Using Lowenthal's method, we have produced a fatal infection in guinea pigs with an orally administered suspension of S. flexneri 2a. This communication describes some of the character-istics of this infection.