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