[Antigenic study of "Serratia marcescens" isolated in France.II.--Characterization of O antigens and description of 5 new O factors, occurrence of serotypes and labelling of new H factors (author's transl)].

The somatic O-antigens of 583 French isolates of Serratia marcescens were studied with the aid of the tube O-agglutination technique sensitized by centrifugation. Flagella antigens were identified by the H-immobilization test. Five new O-antigens (O16 to O20) were found. An antigenic factor (Co) common to isolates of serotypes O12:H9, O14:H12, O14:H20, and O13:H17 is described. Agar cultures of serotypes O12:H9 and O14:H12 dissociated into two colonial types: iridescent colonies, and non-iridescent colonies. Non-iridescent colonies, heated at 100 degrees C, are agglutinated by anti-Co serum, whereas heat-treated iridescent colonies are not. Close relationship between serogroup antigens O6 and O14 observed by traub and Kleber is confirmed. Serogroup O9 was subdivided into two subgroups. In France, 49 different serotypes were identified, with a predominance of serotypes O14:H12, O13:H17 and O3:H12. Recently, several new H-antigens were independently described by Traub and Kleber, and by us. To avoid confusion, these new H-antigens have been herein redesignated in accord with Dr Traub.