CHEMOTHERAPEUTIC STUDIES ON A NEW ANTIFUNGAL AGENT, X-5079C, EFFECTIVE AGAINST SYSTEMIC MYCOSES

Abstract

A new polypeptide antimicrobial drug, X-5079C, is described which has marked activity against Histoplasma capsulatum and Blastomyces dermatitidis infections in mice. The substance is unusual in that it exerts only slight activity against H. capsulatum and B. dermatitidis in vitro. Its antimicrobial spectrum is limited in vitro and/or in vivo in that it is inactive against nonpatho-genic fungi and bacteria and pathogenic bacteria protozoa, viruses, tumors, and dermatophytes. The antifungal agent is of low toxicity in mice, rats, and monkeys. A method for assaying blood, serum, and urine concentrations using Paecilomyces varioti as a test organism is outlined.