Demonstration of ECP on UPEC strains.

<p>(A) CFT073 displays peritrichous pili after growth in LB at 26°C with shaking and after incubation with pre-immune serum followed by negative staining and TEM observation. (B–D) Immunogold labeling of ECP (indicated by arrows) produced by F11 (B), CFT073 (C), and UTI89 (D) strains grown in LB at 26°C with anti-ECP antibodies and rabbit anti-IgG gold conjugate. (E) Magnification of labeled ECP on CFT073. Scale bars represent 500 nm. (F–H) Detection of ECP (green) on UPEC strains [F11 (F), CFT073 (G), UTI89 (H)] after 2 h of incubation with HeLa cells at 37°C and reacted with anti-ECP antibodies and Alexa-Fluor 488-conjugated secondary antibody. Cellular and bacterial DNA was stained with propidium iodide (red). Panel I is the negative control CFT073 incubated with preimmune serum. Images were taken with a 60× objective. The insets in panels F and G are high magnifications of the areas within the corresponding panels and show a fibrillar network (green) between bacteria formed by ECP.