The Protective Action of Dysentery Bacteriophage in Experimental Infections in Mice

Abstract

Dysentery bacteriophage shows good protection, prophylactically and therapeutically, against experimental infections in mice produced by Shigella paradysenteriae Flexner. Dysentery-phage exerts a prophylactic action when given as long as 7 days preceding the infecting dose of 10,000 minimum lethal doses of dysentery bacilli. Heat inactivated dysentery-phage shows no prophylactic action when given as long as 5 days preceding the infecting dose of 10,000 M.L.D. of dysentery bacilli. Treatment with dysentery-phage may be delayed 3 hrs. after the infecting dose of organisms is given. If the dysentery-phage is given 6 hrs. after the infecting dose of organisms, little protection is afforded. Untreated control mice die in about 19 hrs. following the injn. of 10,000 M.L.D. of dysentery bacilli. Quantitative studies show that dysentery-phage can protect mice in the ratio of 1 phage particle to 8 dysentery bacilli when doses of 10,000 M.L.D. of organisms are employed. Lysis of dysentery bacilli in vitro by dysentery-phage is an indication of phage activity in vivo.