Specific staining of bacilli by means of immuno-indian-ink method and immunofluorescent method.

The possibilities for identification of B. anthracis are investigated by means of the Immuno-Indian-ink method (IIIM) and the immunofluorescent method (IFM) in their direct and indirect modifications. The specifity of sera against noncapsulated cells of B. anthrasis increases by their adsorption with antigenically related strains of B. cereus as their vegetative cells and spores are killed beforehand with performic acid. Repeated uses of the bacillus suspension for adsorption is possible by treating it with hydrochloric acid in order to restore its antigenic properties. The adsorbed sera against noncapsulated cells of B. anthracis in the direct and indirect modifications of IIIM and IFM stain specifically the 19 investigated B. anthracis strains but none of the 152 strains of saprophytic bacilli. In addition to that the possibility for differentiation of B. anthracis from saprophytic bacilli is established also by combination of cultivation on selective medium, facilitating the capsule formation of B. anthracis with IIIM and IFM, performed with sera against capsule antigens of the anthrax agent.