COHEN, JAY 0. (Communicable Disease Center, Atlanta, Ga.) AND PER OEDING. Serological typing of staphylococci by means of fluorescent antibodies. I. Development of specific reagents for seven serological factors. J. Bacteriol. 84:735-741. 1962-Fluorescent antibody reagents for identifying seven antigenic factors of staphylococci have been prepared. The fluorescent staining reactions of these reagents were compared to the agglutination reactions with diagnostic cultures of coagulase-positive staphylococci. Correlation between the two serological tests was almost complete with factors a, b, i, and k. The c fluorescent antibody reagent had a somewhat broader spectrum of activity than the corresponding agglutination serum, whereas the m fluorescent antibody reagent stained fewer strains than were agglutinated in m serum. The fluorescent antibody reagent for h factor stained strains possessing hi factor but not strains possessing only h2 factor. Fluorescent antibody reagents for specific staphylococcal factors did not stain strains of group A streptococci. Research into methods of differentiating strains of coagulase-positive staphylococci has received new impetus with the emergence of reservoirs of antibiotic-resistant organisms in hospitals throughout the world. Although phage typing has served as an epidemiological tool in the last decade, its limitations have stimulated research into other means of typing staphylo