Figure 4. FXIIIA contributes to GBS entrapment within fibrin clots.

(A–C) WT GBS COH1 (10⁷ CFU) in 100 μL was incubated with normal human plasma (Normal plasma) or plasma obtained from patients with congenital FXIIIA deficiency (FXIIIA-deficient plasma). Thrombin was added to induce clotting. (A) GBS CFU that were entrapped within the fibrin clot were enumerated. Data are shown as percentage of initial inoculum. n > 5. *P <0.05, unpaired t test. Data are represented as mean ± SEM. (B) Representative scanning electron micrograph showing GBS entrapped in normal plasma or FXIIIA-deficient plasma. Scale bars: 2 μm. (C) In separate experiments, clots obtained from normal or FXIIIA-deficient plasma containing entrapped GBS were washed and incubated in buffer at 37°C for 2 hours. At t = 0 and 2 hours, the number of bacteria released into the supernatant was determined. Data represent mean ± SEM of 4 independent experiments. **P < 0.01, Šidák’s multiple-comparison test following 2-way ANOVA. (D) WT GBS COH1 (10⁷ CFU) was incubated with male or female mouse (B6) plasma. Thrombin was added to induce clotting. GBS CFU that were entrapped within the fibrin clot were enumerated, and data are shown as percentages of initial inoculum. n = 7–10. *P <0.05, unpaired t test. Data are represented as mean ± SEM.