FIG 1.

Effect of cessation of in ovo administration of ceftiofur and replacement with lincomycin-spectinomycin on the proportion of multidrug resistance in ESBL/AmpC resistance gene-positive E. coli isolates in ceftriaxone-enriched samples from newly hatched, broiler, and breeder birds. LS, lincomycin-spectinomycin; No AM, no antimicrobial in ovo; sus, susceptible to all antimicrobial classes; n-sus 1 to n-sus 10, nonsusceptibility to 1 to 10 different antimicrobial classes. 2014 is before and 2015 is after the cessation of ceftiofur in Canada; no isolate was susceptible to fewer than 4 antimicrobial classes in the potential ESBL/AmpC-producing isolate collection.