Epidemics of Shigellosis due to Sorbitol Fermenting Variant of Shigella flexneri 2a in Osaka City

Abstract

A culture of biologically peculiar variant of Shigella flexneri 2a, characterized by sorbitol fermenting property, was encountered at the routine carrier survey performed in this institute on Jan. 31, 1968.
Within supervening two months, there took place three dysentery epidemics in Osaka city, each in a different ward, all of which proved to be caused by the same type as mentioned above.
Positive cultures from these four occasions are totalled in number to 74; one from a carrier, 29 and 40 from two food-borne instances, respectively, and 4 from one intra-familial infection.
Both bacteriological and epidemiological observations were made on it with the following results:
1) Bacteriologically, all 74 cultures of Shigella flexneri 2a were proved to be identical in having. properties of fermenting sorbitol in Barsikows media within 24 hours and requiring cysteine for the growth in Simmons glucose. Further their drug-resistance patterns are all identical, being resistant to SM, and SA and sensitive to TC.
2) On above two epidemics, the authors could trail the sources of infection, a hotel in other prefecture and a restaurant in this city, respectively.
Viewing that incidence of this type of Shigella flexneri 2a, especially of this drug-resistant pattern, . has been very rare (1.3-7.0%), close causative relationship among these four instances and chain-style disseminations of the agents seemed to be highly suggestive.