New Group of Virulent Bacteriophages showing Differential Affinity for Brucella Species

Abstract

BACTERIOPHAGES isolated from Brucella^1–5 are all closely related^3–6 and can be taken as replicas of the international reference type phage Tb of Popkhadze and Abashidze, which identifies the three main species of Brucella⁷: (1) Br. melitensis, which is unsusceptible (although variants sensitive to phage do occur); (2) Br. abortus, which is susceptible at “routine test dilution”, defined as the highest phage dilution producing a reaction of semi-confluent lysis on an appropriate indicator strain; and (3) Br. suis, which is susceptible only at concentrations ten thousand times greater than the routine test dilution. Highly concentrated suspensions of phage Tb produce ε spot of hazy opalescent lysis on lawns of Br. suis, which helps to distinguish it from the other two species.