Studies on the Reciprocal Action of Antibiotics II. The reciprocal action of antibiotics to Salmonella typhi (S57S)

The author studied about the effect of the combinative administrations of each two of the following antibiotics, streptomycin, aureomycin, terramycin and chloromycetin; the tested combinations were 6 as a whole. Salmonella typhi (S57S) was used as a test organism. The results are as follows: 1) The antibacterial actions are co-operative to each other in each of the following combinations; streptomycin and aureomycin, streptomycin and terramycin, aureomycin and chloromycetin, chloromycetin and terramycin, and terramycin and aureomycin. 2) In the combination of chloromycetin and streptomycin, the action of chloromycetin is inhibited by streptomycin, while the action of streptomycin is enhanced by chloromycetin. 3) Among the group of the tested organism, the individual difference of resistance to antibiotics is observed.