[New O (O21) and H (H21-H25) antigenic factors of "Serratia marcescens": subdivision of O factors 5, 10 and 16 (author's transl)].

Five new H factors (H21 to H25) and a new O factor (O21) of Serratia marcescens are described. Factors O5, O10 and O16 were subdivided, and a factor common to groups O2 and O3 was specified. The methods used to prepare specific antisera for O and H identification are also described. Antigenic formula of actually known serovars are reported.