Therapeutic effects of herbal medicines (Juzen-taiho-to and Ryutan-shakan-to) in a rat intrauterine infection (pyometra) model

The herbal medicines Juzen-taiho-to (Shi-quan-da-bu-tang) and Ryutan-shakan-to (Long-dan-xie-gan-tang) have both been used concurrently for the treatment of infectious diseases. We assessed their bacteriologic efficacy in a rat microbial infection (pyometra) model. Aqueous extracts of the herbal medicines were tested in vitro for minimum inhibitory concentration against Escherichia coli and Bacteroides fragilis strains, whereas an aqueous suspension was given orally for the in vivo studies. In concentrations of more than 100 mu g/mL, neither medicine had any effect on the in vitro growth of either E coli or B fragilis. Rats treated with Juzen-taiho-to and Ryutan-shakan-to had significantly decreased uterine viable bacterial cell counts compared with the controls, despite the absence of in vitro antibacterial effects. Active metabolites, lipid-soluble bactericidal components, or altered host defense may account for the discrepancy between the in vivo and in vitro results.