Virulence genes (stx1/stx2/aea) and O serogroups of Escherichia coli strains isolated from the slaughtered cattle and ground meat sold in retail markets in Dakar, Senegal

Abstract

Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen that is involved in foodborne diseases worldwide. In Africa STEC is a concern for food safety, with increasing epidemiological significance. However, data are scarce in countries of sub-Saharan Africa, and particularly in Senegal. The aim of this study was to estimate STEC prevalence and to characterize serogroups and virulence factors in cattle carcasses at slaughterhouse and ground meat sold in retail markets. In total, 298 samples were collected from cattle carcasses (n = 199) and ground meat samples (n = 99). All samples were screened by multiplex PCR for the presence of shiga toxin-encoding genes and intimin. STEC strains (n = 21) identified were characterized for the presence of serogroups, by using agglutination method with specific antisera. The prevalence rates recorded in carcass samples and ground meat were 3.15% and 3.27%, respectively. The O serogroups including O26, O111 and O145 were detected. Among the cattle carcass samples, 1.47% (n = 7) and 2% (n = 8) of the strains carried stx1-stx2 and eae, respectively. Regarding ground meat samples, 2.18% (n = 4) and 1.1% (n = 2) carried stx1-stx2 and eae, respectively. No strain carrying stx/eae association or stx alone was detected in this study. The outcomes of the study shows the need to improve the processing of cattle at slaughterhouses and ground meat, but also to implement routine surveillance of food-borne pathogens throughout the food chain.