FIG. 4.

Fluorescence-activated cell sorter analysis of wild-type, mutant, and complemented strains. Wild-type S. saprophyticus strain 7108, the sdrI knockout mutant, and the complemented mutant were grown overnight in TSB. The bacteria were incubated with antiserum against the SdrI A region, and binding of the antiserum was detected with fluorescein isothiocyanate-labeled anti-rabbit immunoglobulin G. Fluorescence intensity (FL1-H) of particles was counted. The wild-type and complemented strains show high proportions of labeled cells, whereas the mutant does not bind the specific antiserum, as shown by the similarity of the reaction to that obtained with preimmune rabbit serum.