FIG. 6.

Fecal shedding of E. coli O157:H7 by mice. Three groups of six mice received a single oral dose of 10⁸ CFU E. coli O157:H7 strain ATCC 43895 (wild type), the O-antigen-negative mutant (Δper), or the complemented strain (compl). The geometric means of log-transformed viable counts (CFU/fecal pellet) are shown for each strain cultured from fecal samples on the indicated days. E+, fecal cultures positive for E. coli O157:H7 only as determined by using enrichment cultures and containing <10 E. coli O157 CFU/pellet; Neg, feces cultures that were negative as determined by both direct and enrichment culture procedures. The error bars indicate standard errors of the means.