FIG 2.

Biofilm formation capabilities and serum bactericidal resistance of E. coli strains NA114 and NA097. (a) Specific biofilm formation (SBF) after 48 h of incubation. (b) Resistance to human serum, as determined by CFU counting after 3 h of incubation. Strain DH5α was used as a negative control for both experiments, and NA434 served as a positive control (+ve) for the determination of SBF. The experiment was performed in nine replicates for analysis of biofilm formation and six replicates for the serum assay, and statistical values were obtained with the nonparametric Mann-Whitney U test, using GraphPad Prism 5.01. ns, nonsignificant; **, P < 0.01; ***, P < 0.001.