FIG. 6.

Serum complement resistance of strains. The survival percentage was determined for each strain following incubation in 90% guinea pig (GP) or chicken (Ch) serum. (A) Bacteria with the wild-type background. (B) Bacteria with the E. coli K-12 background. The data were obtained from at least 3 independent experiments in which each strain was tested in triplicate. The error bars indicate the standard errors of the means. Significant differences are indicated by asterisks (*, P < 0.05 compared to the parent strain; **, P < 0.005 compared to the parent strain). Abbreviations: pAPEC-1,2,3, pAPEC-1, pAPEC-2, and pAPEC-3; pAPEC-1,2, pAPEC-1 and pAPEC-2; pAPEC-1,3, pAPEC-1 and pAPEC-3; −, no plasmids.