Cross-reactions betweenCorynebacterium sepedonicum andArthrobacter polychromogenes in immunofluorescence staining

Summary In a comparative serological study using indirect fluorescence antibody staining (IFAS) on three strains ofCorynebacterium sepedonicum and eleven strains of the genusArthrobacter, onlyA. polychromogenes cross-reacted withC. sepedonicum. The antiserum titre was 1∶2000 and its dilution was critical for identifying cross-reactions. At dilutions higher than 1∶500, onlyC. sepedonicum showed intense fluorescence and sharp edges of the walls; species ofArthrobacter gave reactions of uncertain interpretations. Some aspects of the immunofluorescence staining technique, the nature of common antigenic determinants, and the applicability of the immunofluorescence staining for detectingC. sepedonicum are discussed. Work supported by grant No 80.00458.06 from the Consiglio Nazionale delle Ricerche, Rome, Italy, Publication No 127.