Enterotoxigenic and enteroinvasive Escherichia coli strains belonging to a new O group, O167.

A new Escherichia coli O group, O167, is described. Its O antigen is related to that of Shigella boydii 3. A total of 29 strains belonging to the new O group were examined. Three strains were determined to be invasive by the Sereny test and by tissue culture tests and were non-enterotoxigenic. All three were nonmotile and failed to decarboxylate lysine. A total of 26 strains were noninvasive. Of these, 25 were motile, 24 decarboxylated lysine, and 19 were enterotoxigenic, 17 producing heat-stable enterotoxin only and 2 producing heat-labile enterotoxin only. This is the first description of the occurrence of enterotoxigenic and enteroinvasive strains in the same E. coli O group.