Fecal Carriage and Whole-Genome Sequencing-Assisted Characterization of CMY-2 Beta-Lactamase-Producing Escherichia coli in Calves at Czech Dairy Cow Farm.

The study aimed to monitor the fecal shedding of cefotaxime-resistant Escherichia coli (CREC) in a cohort of healthy calves on a dairy farm with documented antimicrobial usage and to characterize selected AmpC beta-lactamase-producing E. coli isolates. Fecal samples from 13 suckling calves (1-63 d of age; 113 samples in total) were repeatedly collected and cultivated on MacConkey agar with cefotaxime (2 mg/L).