Effects of growth-promoting antimicrobials on inhibition of Yersinia enterocolitica O:3 by porcine ileal microflora.

The survival of Yersinia enterocolitica serotype O:3 was examined in an in vitro model of the porcine ileum in the presence of normal ileal microflora using a medium supplemented with the growth-promoting antimicrobials avoparcin, spiramycin, tylosin, carbadox and olaquindox, or without any antimicrobials, at 39 degrees C for 5 d. Growth of Y. enterocolitica was inhibited in all trials in the following order: avoparcin < carbadox < spiramycin < no feed additives < tylosin < olaquindox. The media supplemented with avoparcin, carbadox and spiramycin supported the survival of Y. enterocolitica up to 5 d. When incubated with the normal ileal microflora without any growth-promoting antimicrobials, Y. enterocolitica could not be isolated after 4 d. With olaquindox and tylosin, Y. enterocolitica was not detected after 3 d.