GENETIC STUDIES ON THE DEVELOPMENT OF STREPTOMYCIN RESISTANCE IN PASTEURELLA PESTIS

Abstract

P. pestis is very sensitive to streptomycin in vitro and in vivo. A concn. of 1 U./ml. of medium was sufficient to produce 1000-fold reduction in the no. of viable cells on solid medium, and a concn. of 2 U./ml. to sterilize liquid cultures. The mutation rate from streptomycin sensitivity to resistance was low: about 10-11 in avirulent strains and about 10-12 in a virulent strain, 139-L. Streptomycin resistance and virulence were not correlated absolutely in resistant mutants derived from a virulent strain. Streptomycin therapy effective for mice inoculated with a sensitive, virulent strain was ineffective for mice inoculated with a resistant, virulent strain.