Long polar fimbriae contribute to colonization by Escherichia coli O157:H7 in vivo

Abstract

The contribution of long polar fimbriae to intestinal colonization by Escherichia coli O157:H7 was evaluated in sheep, conventional pigs, and gnotobiotic piglets. E. coli O157:H7 strains with lpfA1 and lpfA2 mutated were recovered in significantly lower numbers and caused fewer attachment and effacement lesions than the parent strain.

FIG. 1.

Recovery of E. coli O157:H7 from the feces of sheep inoculated with three isogenic strains. Each symbol represents the geometric mean for one animal over each sampling period. The symbols below the dotted line represent samples that were positive only by enrichment culture. Samples in which no growth was detected by direct plating or enrichment culture are plotted at zero.

FIG. 2.

Recovery of E. coli O157:H7 from the feces of conventional pigs dually inoculated with two isogenic strains. Each symbol represents the geometric mean for one animal over each sampling period. The symbols below the dotted line represent samples that were positive only by enrichment culture. Samples in which no growth was detected by direct plating or enrichment culture are plotted at zero.