ARS Research Brief Highlights E. coli Seasonality, Traceability
The U.S. Department of Agriculture’s Agricultural Research Service (USDA’s ARS) recently published a Research Brief that highlights two food safety studies published in 2022. The first study relates to the traceability of Shiga toxin-producing Escherichia coli O157:H7 (STEC), and the second study discusses the autumn seasonal affects connected to STEC in bagged romaine lettuce.
In the first study, ARS scientists observed a population of 181 STEC strains over a period of 23 years at a at U.S. Meat Animal Research Center closed-system feedlot. The 181 strains collected in the study were subjected to whole genome sequencing (WGS). The study’s findings suggest that diverse subpopulations of STEC can coexist in the same ecological niche, and that strains may be persistent for a long period of time within the same feedlot. Four distinct clades (groups) of the pathogen were observed, which shared a portion of their genetic composition while also containing unique, ‘mobile’ elements. Interpretation of mobile elements during an outbreak investigation may help reveal relationships between human and environmental STEC isolates.