Observations on the Action of Streptomycin in vitro (II). ∗

Abstract

Summary

1. The presence of 1 to 5% or more horse or human serum enhances the resistance of Streptococcus hemolyticus, Streptococcus viridans, Diplococcus pneumoniae, and certain strains of Staphylococcus aureus.

2. Serum in concentrations of 1 to 5% has no effect on the sensitivity of E. coli, E. typhosa, K. pneumoniae, or Aer. aero genes to streptomycin. Higher concentrations of serum may at times enhance the action of streptomycin on certain of these organisms.

3. Streptomycin is effective under certain conditions against stationary or slowly dividing cells, as well as against rapidly dividing cells, provided a sufficient concentration of the drug is used.

4. No direct correlation between the rate of growth of an organism with or without serum and the effect of serum on the sensitivity of an organism to streptomycin can be made at this time.