Effects of griseoviridin and viridogrisein against swine dysentery in experimental infection by using mice and pigs.

Griseoviridin, a known antibiotic produced by Streptomyces cacaoi subsp. cacaoi, was found to be active against Brachyspira hyodysenteriae--the bacterium causing swine dysentery. An in vitro synergism is observed when it is used in combination with viridogrisein--a simultaneously produced antibiotic. In mouse experiments, the effect of griseoviridin alone was less than that of lincomycin--a commercially available swine dysentery medication. However, a 1:1 mixture of griseoviridin and viridogrisein revealed a noticeable synergistic effect. In an evaluation using pigs artificially infected with B. hyodysenteriae, a large difference was not observed between the effect of griseoviridin alone and that in combination with viridogrisein. Nevertheless, griseoviridin alone exhibited a therapeutic effect superior to that of lincomycin.