Identification of Actinomyces, Arachnia, Bacterionema, Rothia, and Propionibacterium species by defined immunofluorescence

Fractionated fluorescein-isothiocyanate (FITC)-conjugated immunoglobulin G (dye-to-protein ratio <10), produced against whole cells of Actinomyces spp., Arachnia, Bacterionena, Rothia, and Propionibacterium spp., give species-specific conjugates with controlled nonspecific staining reactions when appropriately diluted on the basis of their antibody content (10 mg/ml). Using this standardization in immunofluorescence, serotype-specific conjugates are also available after dilution for all serotypes of these organisms except for Actinomyces viscosus type 2, and Propionibacterium acnes type 1. Adequately adsorbed conjugates could be used to differentiate these serotypes from A. viscosus type 1 and P. acnes type 2, respectively. A serological classification in defined immunofluorescence corresponded to species and serotype designation proposed on the basis of other serological analysis and biochemical characteristics. This includes a separation in immunofluorescence of two serotypes of Propionibacterium acnes. The detection of certain actinomycetes of the family Actinomycetaceae and Propionibacterium species by the defined immunofluorescence in direct smears prepared from clinical specimens agreed to 88% with parallel culturing when including a prereduced (PRAS) medium technique for isolation. Qualitative studies revealed that single cells of these organisms could be specifically identified by immunofluorescence when admixed with morphologically similar bacteria and a large number of other contaminants.