Shiga Toxin-Producing (STEC) Associated with Calf Mortality in Uruguay.

In Uruguay, the mortality of dairy calves due to infectious diseases is high. is a natural inhabitant of the intestinal microbiota, but can cause several infections. The aim of the work was to characterize isolates from intestinal and extraintestinal origin of dead newborn calves. Using PCR, virulence gene characteristics of pathogenic were searched. The pathogenic were molecularly characterized and the phylogroup, serogroup and the Stx subtype were determined. Antibiotic susceptibility was determined using the Kirby-Bauer disk diffusion method and plasmid-mediated quinolone resistance (PMQR) genes with PCR. Finally, clonal relationships were inferred using PFGE. Gene characteristics of the Shiga toxin-producing (STEC), Enteropathogenic (EPEC) and Necrotoxigenic (NTEC) were identified. The prevalence of the , , , , , and genes was high and no , , , , , , or were detected. The prevalence of STEC gene in the dead calves stood out and was higher compared with previous studies conducted in live calves, and STEC LEE+ (Enterohemorrhagic (EHEC)) isolates with // genotypes were more frequently identified in the intestinal than in the extraintestinal environment. isolates were assigned to phylogroups A, B1, D and E, and some belonged to the O111 serogroup. and subtypes were determined in STEC. A high prevalence of multi-resistance among STEC and genes was determined. The PFGE showed a high diversity of pathogenic strains with similar genetic profiles. It can be speculated that EHEC (/) could play an important role in mortality. The , and genes could also have a role in calf mortality. Multidrug resistance defies disease treatment and increases the risk of death, while the potential transmissibility of genes to other species constitutes a threat to public health.