Isolation of STEC from Goat Feces

In total, 2,896 fecal samples from healthy-looking goats were collected from different family-scale farms in Lanling County, Shandong Province, China, from November 2017 to October 2021. Fecal samples were collected in 2-mL sterile tubes containing Luria-Bertani (LB) medium in 30% glycerol and transported in bags of ice to the laboratory at the National Institute for Communicable Disease Control and Prevention, China CDC, for the isolation of STEC. Strains were isolated and confirmed by methods described previously (40 (link)). Briefly, after enrichment with E. coli broth (EC broth, Land Bridge, Beijing, China), the samples were examined by PCR for the presence of stx (41 (link)). Samples positive for stx were inoculated onto CHROMagar ECC agar (CHROMagar, Paris, France). After overnight incubation at 37°C, green-blue or colorless colonies on agar were picked and tested for stx by a single-colony duplex PCR assay (40 (link)). API 20E biochemical test strips (bioMérieux, Lyon, France) were used to confirm that all stx-containing isolates were E. coli.