Inhibits bacterial protein biosynthesis by binding to ribosomes. Specifically, binds to the complex of 23S rRNA and ribosomal protein L11 (RPLK) in the 50S ribosomal subunit. While allowing a weak binding of elongation factor G (EF-G) to the ribosome and subsequent GTP-hydrolysis, probably impairs conformational changes in both the ribosome and EF-G which are necessary for translocation. In vitro, inhibits Gram-positive bacteria S.aureus strain 209P (MIC=0.0009 µg,ml), S.aureus strain 133 (MIC=0.0019 µg,ml), S.aureus strain B3 (MIC=0.003 µg,ml), S.aureus strain Hb (MIC=0.003 µg,ml), M.citreus strain ATCC 8411 (MIC=0.0038 µg,ml), M.lysodeikticus strain ATCC 4698 (MIC=0.003 µg,ml), S.lutea strain ATCC 9341 (MIC=0.0011 µg,ml), S.faecalis strain ATCC 9790 (MIC=0.0007 µg,ml), S.viridans (MIC=0.0065 µg,ml), S.pyogenes holyticus strain Dig7 (MIC=0.00028 µg,ml), D.pneumoniae strain Til (MIC=0.00015 µg,ml), N.catrrhalis (MIC=0.0017 µg,ml), L.casei strain ATCC 6633 (MIC=0.003 µg,ml), B.cereus strain ATCC 6630 (MIC=0.0071 µg,ml) and various isolates of L.monocytogenes. In vitro, inhibits Gram-negative bacterium P.multocida strain A125 (MIC=0.0024 µg,ml) but not M.smegmatis strain ATCC 6630, S.typhimurium, A.aerogenes strain ATCC 8308, P.vulgaris, K.pneumoniae strain ATCC 10031, S.marcescens strain A476, P.aeruginosa strain Bass or B.bronchiseptica strain CN387. Does not inhibit Gram-negative bacterium E.coli strain ATCC 9637 but does inhibit purified ribosomes from E.coli. In vivo, has no systic effect in mice infected with staphylococci or streptococci when applied orally or subcutaneously. Has a local effect in mice infected subcutaneously or intraperitoneally with staphylococci when applied immediately afterwards. Is not toxic to mice