Shigella dysenteriae strains having a provisional serovar isolated from imported diarrheal cases in Tokyo

Abstract

Two bacterial strains (ME448 and ME474) isolated from stool cultures of imported cases in Tokyo in 1987 had typical biochemical characteristics of Shigella dysenteriae. The results of antigenic analyses showed that they were serologically identical to each other, but did not belong to any of the established Shigella serovars. These strains were positive for Serény test in guinea pig eye and cell-invasion test in HeLa cells. The strains also had virulence-plasmid encoding outer membrane proteins, indicating that they were pathogenic. We then contacted the Centers for Disease Control in the United States and the Central Public Health Laboratory in the United Kingdom and arranged serological examinations of the strain ME448. From the results, the strain was confirmed to have provisional S. dysenteriae serovar E23507. Although the serovar had been isolated from a Swedish patient who developed diarrhea while in India, this is thought to be the first report of its isolation in Japan.