Application of fluorescent antibody methods in the analysis of plaque samples

Direct FA staining for S mutans serotypes may be performed on smears made from plaque or strain isolates and on colonies attached to agar plates of black membrane filters. Staining with single conjugates directed to S mutans serotypes (a to e) as well as with polyvalent a-, b-, d-, f-fluorescein label and c-, e-rhodamine label conjugates indicate that serotype c is the most common. This is in agreement with many reports by other investigators. Cross-reactions with many S mutans conjugates occurred with organisms resembling Lancefield groups C and G streptococci.