Characterization and molecular subtyping of Shiga toxin-producing Escherichia coli strains in provincial abattoirs from the Province of Buenos Aires, Argentina, during 2016-2018.

We characterized Shiga toxin-producing Escherichia coli (STEC) O157 (n = 20) and non-O157 (n = 68) isolated from carcasses (n = 54), the environment (n = 20), head meat (n = 3) and viscera washing and chilling water (n = 11) in provincial abattoirs before and after implementing improvement actions. The strains were tested for eae, saa, ehxA and fliC(H7) genes. Variants stxi and stx(2) were also determined. Pulsed-field gel electrophoresis (PFGE) was carried out with restriction enzymes XbaI and BlnI. All twenty O157 STEC strains [H7; H21; HNM] carried genes rfb(O157) and ehxA; 90.0 % were positive for eae and 15.0 % were negative for fliC(H7) and positive for saa. Results of PFGE showed 17 Xbal patterns, of which 14 were unique and three formed clusters. From the 68 non-0157 STEC strains, 66.2 %, 55.9 % and 2.9 % were positive for ehxA, saa and eae genes, respectively. Fifty-three XbaI patterns were obtained (49 unique and four forming clusters). Cross-contamination between products and between the environment and products was confirmed in all abattoirs. While the proposed improvements reduced the risk of contamination, Good Hygiene Practices and Good Manufacturing Practices should be implemented in provincial abattoirs, stressing the importance of having a uniform national food safety standard.