Serotyping of Serratia marcescens: evaluation of Le Minor's H-immobilization test and description of three new flagellar H antigens.

The H-immobilization test of Le Minor for determining flagellar (H) antigens was evaluated and compared with tube and slide H-agglutination tests. The test proved specific and easy to perform, and titration end points were clearly discernible. The degree of serological cross-reactivity between H antigen reference strains of Serratia marcescens was low. Consequently, this test was adopted for routine serological analysis of H antigens, using unabsorbed rabbit immune anti-H sera. As a result of using this procedure, three new provisional H antignes, designated H14, H15, and H16, are proposed.