Immunological detection of bacterial pathogens with antibody-containing magnetic gel

A process for the immunobacteriological detection of pathogenic germs possessing specific antigenic determinants, in biological media supposedly contaminated by such pathogenic germs, with the aid of a magnetic gel to which are coupled anti-specific antigenic determinant antibodies, which process is characterized by the following steps:

• (a) a biological medium supposedly contaminated by a pathogenic germ possessing a specific antigenic determinant is brought into contact with particles of the magnetic gel to which the said antibodies are coupled for a sufficient time to permit the fixing to the gel of the pathogenic germs possessing the said antigenic determinants contained in the biological medium;
• (b) the particles of magnetic gel are then removed from the mixture by magnetic means and
• (c) are inoculated onto a nutrient agar medium,
• (d) the agar medium containing the magnetic particles is incubated to develop culture colonies of the pathogenic germs;
• (e) areas containing serum containing antibodies specific to the pathogenic germ to be detected are then formed in the agar in the vicinity of the magnetic particles covered with culture colonies, embedded in the agar,
• (f) the germs are lysed by means of lysing agents,
• (g) the lysate is incubated with the serum for a time enabling the serological antibody-antigen reaction to take place by immunodiffusion on the agar, and to form a precipitation band, and
• (h) the quantity of germs contained in the biological medium is read directly, by virtue of the antigen-antibody reaction on the agar.