Antimicrobial Action of Terramycin in Vitro and in Vivo.

Abstract

Discussion and Summary

The data reported in this and in a previous communication by Finlay et al.(1) emphasize the strong antimicrobial activity of terramycin and its salts against a wide variety of aerobic and anaerobic gram-positive and gram-negative bacteria, and against certain of the rickettsiae. In addition, attention is called to the possible tuberculostatic activity of this compound. Terramycin is absorbed readily following oral or parenteral administration and is a highly effective chemotherapeutic agent, active against a variety of experimental infections in mice. A comparative study of the chemotherapeutic activities of terramycin and its salts indicates that the highly insoluble amphoteric form of terramycin as well as its more soluble salts are all chemotherapeutically effective. In most instances, the CD₅₀ of the hydrochloride has been less than that of the other forms of terramycin, especially when administered by the oral route. More satisfactory results, as indicated by lower CD₅₀ values, have been obtained in some in fections, however, with terramycin (amphoteric) when therapy was carried out by means of a single injection. It is possible that this enhanced chemotherapeutic effect, observed in these infections when treatment is carried out by a single injection only, may be a reflection of the low solubility and slow absorption of terramycin in the amphoteric form.

The toxicity of terramycin has been studied extensively by P'an and his associates (12). It is possible that the main virtue of terramycin resides in its remarkably low toxicity and low chemotherapeutic index. Terramycin, however, is a highly effective chemotherapeutic agent against experimental animal infections and it is believed that terramycin may prove of value in the treatment of certain human infections due to terramycin-sensitive organisms. A therapeutic evaluation of terramycin in human infections, therefore, has been initiated.