NOVEL ANTIBIOTICS, A PROCESS FOR PRODUCING THE SAME, MEDICAL COMPOSITIONS CONTAINING THE SAME, AND A NOVEL STRAIN OF THE GENUS STREPTOMYCES FOR USE IN PRODUCING THE SAME

摘要

A KA-6643-series antibiotic comprising at least one substance represented by any of the following formulae, or a salt or ester thereof:

is effectively useful as an antibacterial and beta -lactamase inhibiting agent and can be produced by culturing a strain belonging to the genus Streptomyces which can produce the KA-6643 substances, and isolating the antibiotic from the culture broth.