TABLE 1.

Detection and quantification of ESBL-producing E. coli in pairs^a

^aDifferent shades of gray indicate the concentration of ESBL-producing E. coli, expressed as the log₁₀ number of CFU per gram of feces; darker colors correspond to higher ESBL-producing E. coli concentrations. I, infected and infectious, ESBL-producing E. coli-challenged chick; S, susceptible chick; ND, not determined; + or − for sentinel chicks, the presence or absence of ESBL-producing E. coli in mixed droppings of sentinel chicks, respectively (+/− represent the results for each sentinel chick in the pair); §, D1 is the day of ESBL-producing E. coli challenge of 5-day-old chicks; cloacal swab specimens were taken right before challenge; ±, 0 values for I or S chicks are not expressed as the log₁₀ number of CFU per gram of feces but indicate no ESBL-producing E. coli detection; ¥, from D4, S, I, and sentinel chicks were housed together; #, days 4 to 6 each had two sampling points (9 a.m. and 4 p.m.); ≠, sentinel chicks were housed in pairs in one cage; results are derived from two mixed droppings from two sentinel chicks, unless otherwise stated; *, single cloacal swab specimens were taken from each sentinel chick per pair.