A Method for Detecting Chemotherapeutic Activity by an in Vivo–in Vitro Test in Mice

Summary: A modification of existing in vivo–in vitro techniques for ‘screening’new chemotherapeutic agents is reported. Examples are given of its assessment with several antibiotics. Serum from mice inoculated intraperitoneally with the antibiotics was serially diluted in an indicator medium and assayed against the Oxford staphylococcus. By means of standards diluted in the same medium the amount of antibiotic/ml. of serum was calculated. Six known antibiotics were used in these investigations and determinations made of the lowest dose that would give a detectable level; the level given over a period of hours by a standard dose, i.e. 40 mg./kg., and a comparison between mice and guinea pigs using the standard dose.