Abstract
In studying the mode of action of penicillin on bacteria, Hobby, Meyer, and Chaffe 1 and Lee, Foley, and Epstein 2 observed that multiplication must take place to get killing action and that the more rapid the growth of bacteria the greater the rate of destruction. Waksman and Woodruff 3 found the reverse to be true in the case of actinomycin and streptothricin. With these two antibiotics it was more difficult to inhibit bacteria on a good medium than it was on a poorer medium. The study reported here is an attempt to determine the action of streptomycin on bacteria and to see if this action was similar to either the action of penicillin or of actinomycin and streptothricin.
The streptomycin was prepared at the University of Illinois in the laboratories of H. W. Anderson and purified and standardized in the laboratories of H. E. Carter. 4 , 5 The unit used is practically the same as the Waksman dilution unit. 6
Eberthella typhosa (Hopkins strain) and Staphylococcus aureus (FDA 209) were used as the test organisms, and were tested against the streptomycin according to the following procedure.
The following media were compared: (1) nutrient broth, (2) nutrient broth diluted with an equal amount of water, and (3) brain heart infusion. Because the presence of phosphate and NaCl might affect the action of streptomycin it was thought not advisable to use Difco brain heart infusion, but instead the brain heart infusion was made according to the following procedure. Five hundred g of ground beef heart were infused with 1000 ml of water and 500 g of beef brain were similarly treated. These infusions were separately filtered through gauze, heated to boiling and filtered again.
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