Evaluation of Germicidal Efficiencies of a Group of Antibiotics Tested by Tissue Culture Technic

Summary A new method was proposed recently for the evaluation of germicides intended for clinical application. Iodine, with a toxicity index of 0.10 exhibited the greatest degree of germicidal efficiency. The same procedure was followed for the evaluation of a group of antibiotics. Penicillin G sodium gave an index of 0.0024 which indicated that it was more than 400 times more toxic to the test organism, Micrococcus pyogenes var. al-bus, than to the tissue cells, and approximately 42 times more efficient than iodine. Results on other antibiotics in order of decreasing efficiency are: Streptomycin sulfate, 0.02—; Polymyxin B sulfate, 0.63—, Terra-mycin, 0.67. Bacitracin and Chlorampheni-col were bacteriostatic and could not be evaluated. Likewise, Aureomycin HC1, Achro-mycin HC1, and Erythromycin could not be evaluated; the former two precipitated from solution shortly after being prepared, and the latter failed to dissolve in saline.