Colostrum as a source of ESBL-Escherichia coli in feces of newborn calves.

The aim of the present study was to determine if colostrum and the equipment for harvesting and feeding colostrum are sources of fecal ESBL/AmpC-producing Escherichia coli (ESBL/AmpC-E. coli) in calves. Therefore, 15 male calves fed with pooled colostrum on a dairy farm and held individually in an experimental barn, the colostrum pool and the equipment for harvesting and feeding colostrum were sampled and analyzed for the occurrence of ESBL/AmpC-E. coli. The ESBL-AmpC-E. coli suspicious isolates were subjected to whole-genome sequence analysis. Forty-three of 45 fecal samples were tested positive for ESBL/AmpC-E. coli. In the colostrum sample and in the milking pot, we also found ESBL/AmpC-E. coli. All 45 E. coli isolates were ESBL-producers, mainly commensal sequence type (ST) 10, but also human-extraintestinal pathogenic E. coli ST131 and ST117 were found. The clonal identity of six fecal isolates with the ESBL-E. coli isolate from the colostrum and of five fecal isolates with the strain from the milking pot demonstrates that the hygiene of colostrum or the colostrum equipment can play a significant role in the spread of ESBL-E. coli. Effective sanitation procedures for colostrum harvesting and feeding equipment are crucial to reduce the ESBL-E. coli shedding of neonatal dairy calves.