Clark, Harold W. (The George Washington University, Washington, D.C.), Jack S. Bailey, Richard C. Fowler, and Thomas McP. Brown. Identification of Mycoplasmataceae by the fluorescent antibody method. J. Bacteriol. 85:111-118. 1963.-The conditions of the fluorescent antibody reactions were studied in relation to their application to Mycoplasmataceae or pleuropneumonia-like organisms (PPLO). Mycoplasma hominis type 1 and 2 antigens and their homologous antisera were used to determine the activity and specificity of these and other strains. Fluorescein isothiocyanate conjugated antiserum globulin preparations were used in both the direct and indirect fluorescent antibody methods. A direct tube technique was used for the detection and measurement of growth in broth cultures by the addition of conjugated antiserum. The specific fluorescent staining and recognition of hot water fixed M. hominis colonies was presented as a suitable identification standard. The antigenic activity was found to remain in the insoluble residue after exposure of M. hominis strains to sonic vibration (9 kc) for 30 min and centrifugation. Brief 2-min exposures of tissue cells to vibration (9 kc) caused the disruption of tissues, with the release of viable and "bound" nonwashable strains that reacted specifically with fluorescent antibody. It is proposed to apply both the sonic vibration and the fluorescent antibody techniques for the identification of Mycoplasmataceae in human tissues.