Abstract
In a previous communication 1 a comparison was made of the resistance of Staphylococcus aureus, Eberthella typhi and embryonic chick heart tissue to Merthiolate and phenol. Toxicity indices were determined by dividing the highest dilution of the germicide that killed the tissue by the highest dilution of the chemical showing no growth of the test organism. Using Staphylococcus aureus as the test organism the toxicity index for phenol was found to be 12 and for Merthiolate about 35. It was concluded that phenol possessed a lower toxicity index than Merthiolate when tested by the tissue culture method. Theoretically the smaller the toxicity index the more nearly perfect the chemotherapeutic agent.
In the present paper a comparison was made of the resistance of Staphylococcus aureus and embryonic chick heart tissue to Metaphen and phenol. The methods employed were the same as those given in the first paper.
A Staphylococcus aureus phenol coefficient was determined for aqueous Metaphen∗ by the method of Reddish. 2 Phenol killed Staphylococcus aureus in a dilution of 1–65 in 10 minutes but not in 5 minutes. The highest dilution of Metaphen killing Staphylococcus aureus under the same conditions was found to be 1–6,000. Therefore, the Staphylococcus aureus phenol coefficient was 92.
Birkhaug 3 reported a phenol coefficient of 1500. We are at a loss to explain such a great difference in the Staphylococcus aureus phenol coefficients of Metaphen when tested by the same method.
Buchsbaum and Bloom 4 reported that Metaphen killed Staphylococcus aureus in a concentration of 1–100,000 in cultures of chick periosteal cells. Since their methods differed widely from those employed here no comparisons can be made with their work.
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