Fred R. Evans

Stimulation of Sporogenic and Nonsporogenic Bacteria by Traces of Penicillin or Streptomycin

Summary Suitable, low concentrations of penicillin or streptomycin in sterile milk (autoclaved) stimulated the growth of many spore-formers and Staphylococcus aureus and Streptococcus agalactiae. The degree of stimulation differed with the organism and with some cultures was not apparent in the range of concentrations used; some of the practical implications of growth stimulation by penicillin and streptomycin are briefly discussed.

Penicillin as a Sporicidal Agent

Summary Under suitable conditions of incubation, penicillin in relatively low concentration is actively sporicidal against many aerobic species of bacteria. In sensitive species the sporicidal activity of penicillin is much greater in milk than in water and is usually enhanced by sublethal heating of the spores before treatment with penicillin.