Somatic (O) group tests. Test as in E-6a, above, using individual group somatic (O) antisera including Vi, if available, in place of Salmonella polyvalent somatic (O) antiserum. For special treatment of cultures giving positive Vi agglutination reaction, refer to sec. 967.28B in Official Methods of Analysis (1). Record cultures that give positive agglutination with individual somatic (O) antiserum as positive for that group. Record cultures that do not react with individual somatic (O) antiserum as negative for that group.