Inhibitory Effect of Sulfamonomethoxine on Capsule Antigen Formation of Bordetella bronchiseptica

Abstract

The authors reported that K antigen formation of sulfamonomethoxine (SMMX)-resistant Bordetella bronchiseptica is inhibited by SMMX in vitro. The present study was conducted to determine whether inhibition occurs also on the pig's concha nasalis in vivo, using experimentally infected pigs. SMMX in form of a feed added at the rate of 500 ppm was administered consecutively from one day before bacterial inoculation to the day of autopsy, which was performed 11 and 25 days after bacterial inoculation. The SMMX-administered group showed distinct inhibition of bone atrophy of the concha nasalis (AR lesion) both macroscopically and electron microscopically, in contrast to the control group. Decrease in viable cell count of B. bronchiseptica in the concha nasalis was noted in the former group. The serum agglutination titer in the former group decreased to a low value. K antigen formation of SMMX-resistant B. bronchispetica would thus appear to be inhibited in the presence of SMMX on the pig's concha nasalis, leading to inhibition of AR lesions.