This study investigated the antimicrobial activities of Oriental medicinal plant extracts against four Shigella species, i.e., Shigella sonnei, Shigella flexneri, Shigella boydii and Shigella dysenteriae. Twelve Oriental medicinal plants were extracted with 80% ethanol. When the Rhus javanica extract was used at 0.01% concentration, 98.09% of the S. sonnei cells were injured. And S. boydii showed significantly different percentages of injured cells at 0.01% and 0.5% of R. javanica extracts, and S. dysenteriae at 0.01%, 0.1% and 0.5% concentrations of the extracts (P < 0.05). Among the tested Shigella species, S. sonnei was the most easily injured, showing a higher percentage of injured cells at low R. javanica extract concentrations. The growth inhibitory effects of the R. javanica and Terminalia chebula extracts on the Shigella species at different concentrations (i.e., 1, 10 and 100 ppm) were calculated using the modified Gompertz equation. R. javanica extracts used at 100 ppm inhibited the growth of S. flexneri and S. dysenteriae for the entire cultivation period (>48 h). However, the T. chebula extract used at the same concentration did not completely inhibit the growth and caused an increased lag time corresponding to 227.0% and 174.4% for S. flexneri and S. dysenteriae, respectively.
Shigellosis results in at least 600,000 deaths worldwide each year. And in the U.S.A., it is a major bacteria involved in food poisoning, reported in 10,000–20,000 patients (Centers for Disease Control and Prevention). In the present study, ethanol extracts of oriental medicinal plants were used as basic materials for controlling Shigella species, and there are potentials for medicinal plants, as a natural antimicrobial agent, to be used in the development of eco-friendly reduction technology on Shigella species.