Brachyspira hyodysenteriae strain A41 dTDP-glucose 4,6-dehydratase (rfbB), glucose-1-phosphate thymidylyltransferase (rfbA), and dTDP-4-keto-L-rhamnose reductase (rfbD) genes, complete cds; and dTDP-4-dehydrorhamnose 3,5-epimerase (rfbC) gene, partial cds