Purpose: The purpose of this study is to determine the prevalence of E. coli non-O157:H7 STECs in beef in Mexico.
Methods: Samples were collected at beef processing plants in three major cities in Mexico. In addition to market samples collected in one city, hide, pre-evisceration, and post-evisceration samples were collected using sponges hydrated with buffered peptone water. All samples were then enriched in Tryptic Soy Broth (TSB), incubated at 37°C for 18 h, and processed in accordance with standard BAX protocols (Dupont Qualicon).
Results: The hide, pre-evisceration, and post-evisceration prevalence varied by city with rates in city one being 96.9% (n = 65), 76.9% (n = 65), and 80.8% (n = 65), respectively; city two 100% (n = 25), 50% (n = 25), and 0% (n = 25); and city three 100% (n = 20), 100% (n = 20), and 75% (n = 20). The prevalence in market samples from city three was 5.7% (n = 105). Serogroups O121, O126, and O103 were the most common, with prevalence rates as high as 96.7% in city two’s hide samples, while O111 was the least common serogroup with prevalence rates of 0%-30%.
Significance: Contamination of food animals and food products with E. coli non-O157:H7 STECs can pose an important public health risk, especially to populations most susceptible to E. coli infections. While E. coli O157 has been reported at low prevalence in Mexico, this study effectively establishes that other STECs need to be addressed and controlled in Mexico.