Fig. 1

In vitro and in vivo detection of pneumococci with fluorescently-labelled antibodies. Strain TIGR4 (A) was mixed with anti S4-A488 (green) antibody and observed under a epifluorescence microscope within five minutes. (B) Spn serotype 19F strain 4924 was cultured for four h in a 8-well slide and pneumococci attached to the substratum were stained with an anti S19-A555 (red) antibody and the DNA was stained with DAPI. (C-D) Human pharyngeal cells grown to confluence were inoculated with (C) strain D39 or (D) a mixture of strain D39 and strain TIGR4 and incubated for four hours. D39 was stained with S2-A555 (red) and TIGR4 was stained with S4-A488. In panel C, DNA was stained with TO-PRO-3, while in panel D, it was stained with DAPI. (E-F) C57BL/6 mice (N = 11) were intranasally inoculated with serotype 19F strain EF3030. After 48 h, mice were euthanized, and the nasal bone was removed. Nasopharyngeal tissue was collected, sectioned (∼5 μm), or homogenized. Nasopharyngeal homogenate (E) or tissue sections (F) were stained with DAPI and with an anti S19-A555 antibody. Arrows point out Spn. In panels B-F, micrographs were obtained by confocal microscopy, and the projection of z-stacks is shown. (G) Nasopharyngeal homogenates were diluted and plated to obtain the bacterial density. The density in the plot was grouped according to whether the samples yielded a positive reaction with Spn-FLUO or were not detected (ND). Student t test, **p = 0.01