Hygromycin A, an antitreponemal substance. I. Screening method and therapeutic effect for Treponema hyodysenteriae-caused infection in CF-1 mice.

In vitro and in vivo screening methods were established for the discovery of new active substances against Treponema hyodysenteriae. During the screening methods, hygromycin A produced by Streptomyces hygroscopicus KA-355 was found to be active against T. hyodysenteriae. Hygromycin A did not show high antitreponemal activity in in vitro test using the paper disc method on the agar plate inoculated with T. hyodysenteriae. However, the antibiotic exhibited highly therapeutic effect in CF-1 mice, compared with of lincomycin, tiamulin, lankacidin C or olaquindox drinking water. The effective dose (ED50) of hygromycin A was 1.1 micrograms/ml.