Genetic characterization of Shiga toxin-producing Escherichia coli O26:H11strains isolated from animal, food, and clinical samples

KRÜGER, A.; LUCCHESI, P. M. A.; SANSO, A. M.; ETCHEVERRÍA, A. I.; BUSTAMANTE, A.V.; BURGÁN, J.; FERNÁNDEZ, L.; FERNÁNDEZ, D.; LEOTTA, G.; FRIEDRICH, A. W.; PADOLA, N. L.; ROSSEN, J. W. A.

Frontiers in Cellular and Infection Microbiology

Frontiers

Año: 2015 vol. 5 p. 1 - 8

2235-2988

The Shiga-toxin producing Escherichia coli (STEC) may cause serious illness in human.Here we analyze O26:H11 strains known to be among the most reported STEC strainscausing human infections. Genetic characterization of strains isolated from animal,food, and clinical specimens in Argentina showed that most carried either stx1a orstx2a subtypes. Interestingly, stx2a-positive O26:H11 rarely isolated from cattle in othercountries showed to be an important proportion of O26:H11 strains circulating in cattleand food in our region. Seventeen percent of the isolates harbored more than onegene associated with antimicrobial resistance. In addition to stx, all strains contained thevirulence genes eae-β, tir, efa, iha, espB, cif, espA, espF, espJ, nleA, nleB, nleC, and iss;and all except one contained ehxA, espP, and cba genes. On the other hand, toxB andespI genes were exclusively observed in stx2-positive isolates, whereas katP was onlyfound in stx1a-positive isolates. Our results show that O26:H11 STEC strains circulatingin Argentina, including those isolated from humans, cattle, and meat products, present ahigh pathogenic potential, and evidence that cattle can be a reservoir of O26:H11 strainsharboring stx2a.