Pathogenicity, Antigenic Relationships and Evolutionary Trends of Shigella Alkalescens

Abstract

From a small population in a restricted area an almost perfect biochemically intergrading series of cultures from Shigella alkalescens to Escherichia coli were isolated which were antigenically identical or closely related. There is some evidence indicating that Shigella alkalescens and antigenically related cultures may have caused an epidemic of gastroenteritis in infants in the nursery of a general hospital. One hundred and forty-one biochemically typical Shigella alkalescens strains and 42 cultures intergrading biochemically from Shigella alkalescens to Escherichia coli possessed somatic antigenic fractions ABCD, ABCDE or ABCE. Major antigen A appears to be a Shigella alkalescens species specific antigen, major antigen B was found in paracolon and coliform bacteria, minor antigen C occurred in Shigella paradysenteriae, paracolon and coliform cultures and minor antigens D and E were found in paracolon and coliform bacteria. One or more untyped minor antigens were found common to Shigella alkalescens and paradysenteriae but not to paracolon or coliform bacteria.