Antibiotic 107891, its factors A1 and A2, pharmaceutically acceptable salts and compositions, and use thereof

The invention relates to an antibiotic substance of microbial origin, arbitrarily denominated antibiotic 107891 which is produced by fermentation of Microbispora sp. ATCC PTA-5024, the pharmaceutically acceptable salts and compositions thereof, and their use as an antibacterial agent having inhibitory activity versus susceptible microbes. Antibiotic 107891, which is a complex comprising two Factors, denominated Factors A1 and A2, has a peptide structure containing lanthionine and methyllanthionine as constituents which are typical characteristics of the antibiotics of the lantibiotics group. Antibiotic 107891 and its Factors A1 and A2 show a good antibacterial activity against Gram-positive bacteria including methicillin resistant and vancomycin resistant strains, and is active also against some Gram-negative bacteria such as M. catharralis, Neisseria species and H. influenzae and Mycobacteria.