Novel antibiotic U-64,767 producible in a fermentation under controlled conditions using a biologically pure culture of the microorganism Streptomyces macronensis Dietz sp.n., NRRL 12566. This antibiotic is active against various Gram-positive bacteria, for example, Staphylococcus aureus and Streptococcus pyogenes. It is also active against the Gram-negative bacterium Streptococcus pneumoniae. Thus, antibiotic U-64,767 can be used in various environments to eradicate or control such bacteria.