Chemotherapeutic Evaluation of Rifampicin to Experimental Bacillary Dysentery in Cynomolgus Monkeys

ABSTRACT Chemotherapeutic effect of rifampicin (RFP) and kanamycin (KM) to bacillary dysentery was evaluated using cynomolgus monkeys experimentally infected with Shigella flexneri 2a. Monkeys manifested typical symptoms of the disease after rectal administration of the bacilli. They were orally treated one or two days after challenge with a daily dose of 200 mg of RFP or KM per animal for five consecutive days. These monkeys were investigated clinically, bacteriologically and histopathologically. A more rapid improvement of the stools from a bloody mucous to a normal with disappearance of the bacilli in stools was observed in RFP treatment as compared with KM treatment. Reappearance of bacilli in the stools was observed from six to eight days after the last administration with KM. A more significant inhibitory effect with RFP was observed in penetration and multiplication of the bacilli within host epithelial cells than with KM. A greater part of the animals treated with KM revealed, as seen in non‐treated controls, catarrhalic colitis associated with penetration and multiplication of the bacilli in epithelial cells or in the lamina propria. However, no histological changes were observed in cases treated with RFP with the exception of one case with microfoci in the ileocecal valve.