Mode of action of the cyclic depsipeptide antibiotic LL-AO34β1 and partial characterization of a Staphylococcus aureus mutant resistant to the antibiotic

The antibacterial activity of the cyclic antibiotic LL-AO341β 1 was examined. The antibiotic was a narrow spectrum agent, effective principally against Gram-positive organisms. The intrinsic insusceptibility of Escherichia coli was due to exclusion of the drug by the outer membrane. The antibiotic was bactericidal against Staphylococcus aureus, and cell death was associated with lysis of the bacteria. The antibiotic did not specifically inhibit the synthesis of DNA, RNA, protein, lipid or peptidoglycan since these synthetic activities continued for several minutes after exposure to lethal concentrations of the antibiotic and then all abruptly ceased between about 8 and 15 minutes post antibiotic exposure