Crypt colonization profiles in response to strain preexposure. (A) Timeline of a head start cocolonization experiment. Each experiment consisted of a mixed inoculum with CFP- and YFP-labeled strains with (+) or without (−) the initial fluorescently labeled single-strain inoculum. The frequency of crypts with each strain type is shown. Each experiment was performed three times and is presented as an individual trial. (B) Mixed inoculum, CFP- and YFP-labeled ES114; initial inoculum, CFP-labeled ES114. (C) Mixed inoculum, CFP- and YFP-labeled FQ-A001; initial inoculum, YFP-labeled FQ-A001. (D) Mixed inoculum, CFP-labeled ES114 and YFP-labeled FQ-A001; initial inoculum, CFP-labeled ES114.