New antibacterial agent (U-24,544) isolated from Streptomyces griseus.

Antibiotic U-24,544 is a new agent isolated from the culture broth of a streptomycete strain. The antibiotic inhibits a variety of gram-positive and gram-negative bacteria in vitro, but is ineffective in treatment of experimental bacterial infections in mice. It is fairly cytotoxic in mammalian cell cultures and remarkably nontoxic in mice.