On the serological relationship between Salmonella O-groups 48 and 64 and the corresponding Arizona O-groups 5 and 29 which would justify a merger of these groups.

In 1963 Kauffmann divided O-group Y (O:48) of the Kauffmann-White schema into 3 sub-groups, e.g. 48(1),48(2) (S. dahlem), 48(1),48(2),48(3) (S. djakarta), 48(1),48(3),48(4) (Citrobacter 2624/36). He also recommended the use of the two serotypes S. dahlem and S. djakarta for the preparation of a diagnostic group-serum. At that time, serological relations--especially O-antigenic relations (and even some identities)--between the separate Salmonella and Arizona genera were known, viz. between the Salmonella group O:48 and the Arizona group O:5. It has now been found that there exist also close serological relations between the Salmonella O-groups 48 and 64 on the one hand and to the corresponding Arizona O-groups 5 and 29 on the other hand, in connection with which the special factor 48(4) defined by Kauffmann in the Citrobacter culture 2624/36 enbraces the whole Salmonella group O:64 (Arizona group O:29). Therefore, every Salmonella O:64 strain and Arizona O:29 serotype respectively can be agglutinated with factor-serum 48(4), defined by Kauffmann. A special O:64 serum is no longer required. The Salmonella antigen 64 (Arizona O:29 or O:5,29) has as a rule the partial antigens 48(1),48(3),48(4) (Arizona O:29). Only a few serotypes do not possess factor 48(3): their components are 48(1) and 48(4) (Arizona O:29). The evidence of our findings demonstrates that the Salmonella O-group 64 (Arizona O:29) should be combined with O-group 48 (Arizona O:5) and erased from the original Kauffmann-White schema and the Arizona antigenic schema to avoid a wrong diagnosis.