Molecular epidemiology of Shiga toxin-producing O113:H21 isolates from cattle and meat

PADOLA, N. L.; CÁCERES, M. E.; KRÜGER, A.; PADOLA, N. L.; CÁCERES, M. E.; KRÜGER, A.; LUCCHESI, P. M. A.; FERNÁNDEZ, D.; CADONA, J. S.; ALFARO, R.; SANSO, A. M.; BUSTAMANTE, A. V.; FERNÁNDEZ, D.; LUCCHESI, P. M. A.; CADONA, J. S.; ALFARO, R.; SANSO, A. M.; BUSTAMANTE, A. V.

ZOONOSES AND PUBLIC HEALTH

WILEY-BLACKWELL PUBLISHING, INC

Año: 2018 vol. 65 p. 569 - 577

1863-1959

The serotype O113:H21 is considered one of the relevant non-O157 STEC serotypesassociated with severe human infections. Due to the increased detection of O113strains and their relationship with clinical cases, which emphasizes the importance ofthis serogroup as an emerging pathogen, our aim was to determine the characteristicsof STEC O113:H21 strains circulating in bovine cattle and retail meat from Argentina.For this purpose, we determined the presence and combinations of various virulencegenes (and their variants) related to adhesion and toxicity in a collection of 34 isolates.Their genetic relatedness using multiple-locus variable-number tandem repeat analysis(MLVA) was also studied. Subtyping of stx genes indicated that O113:H21 strainscirculating in Argentina mainly present stx2a alone or together with stx2c or, less frequent,with stx2d, all of which are subtypes associated with human disease. We foundplasmid markers, such as saa, ehxA and subA, in a higher proportion than previousstudies, and five variants of saa, two of which were novel ones. In relation to MLVAsubtyping, we detected a limited diversity among the isolates considering that severalloci were not discriminative and, that in some farms, the same clone seemed to remaincirculating throughout the year. The O113:H21 strains studied harbour several toxinand adhesion genes (saa, espP, fimCD, ehaA, iha, hcpA, elfA, lpfO113, ecpA, subA, cdt-V)and Stx subtypes associated with human disease. Results also highlighted that subtypingof stx and saa is useful to discriminate O113:H21 strains that share virulencegenes. In conclusion, this study shows that a number of O113:H21 strains that occurin foods and bovines could be pathogenic for humans. This situation calls for furtherattention in the prevention and control of foodborne disease caused by these strains.