FIG 6.

(a) Hypothetical model of streptococcal pharyngitis. Plasma exudes into the airway lumen and mixes with saliva. The coagulation system is activated, and the bacteria are entrapped in clots. In the absence of a bacterial response, the clots and bacteria are cleared by swallowing, whereas the bacterial response results in plasmin activity, clot dissolution, and counteraction of clearance. The gray line represents the epithelium as well as the time axis. (b) Test of the hypothesis. Fluorescence-labeled G45 bacteria with or without the addition of the protein synthesis inhibitor chloramphenicol were incubated at an epithelial cell surface covered in PBS, saliva, or a saliva-plasma mixture, with or without heparin to inhibit coagulation. The cells were washed, and the fluorescence associated with them was measured. Shown are individual values, median, and 95% CI for four replicates in two blocks with different bacterial cultures for replicates and different donors of saliva and plasma for blocks.