Hemagglutination by the Koch-Weeks bacillus (Hemophilus aegyptius).

The ability of certain viruses, notably influenza, to agglutinate red blood cells has led to a very useful immunological technique. Certain bacteria also have been reported to possess this capacity by Kraus and Ludwig (1902), Pearce and Winne (1904), Guyot (1908), and Fukuhara (1909). More recently Keogh et al. (1947, 1948) have shown that Hemophilus pertussis, Hemophilus parapertussis, and Hemophilus bronchisepticus also have the ability to clump the erythrocytes of various species of animals and have suggested that the virulence of strains of H. pertuasi is related to their hemagglutinin content. Shigella alkalescens also agglutinates the erythrocytes of humans and of certain other animals, whereas some other species of Shigella fail to do this (Griffitts, 1948). In connection with the study of strains of Hemophilus recovered from cases of acute conjunctivitis in Texas (Pittman and Davis, 1950), an investigation of the capacity of these strains to agglutinate the red blood cells of various species was made. It was found that the strains identified as the Koch-Weeks bacillus possessed a hemagglutinin whereas Hemophilus influenzae did not. In this paper the details of the investigation of this reaction will be described.