RESUMEN
Shiga toxin-producing Escherichia coli (STEC) O157:H7 is a worldwide concern. Cattle are their main reservoir and may contaminate watercourses through manure. We characterized a collection of 38 STEC O157:H7 strains isolated from surface water in feedlots areas (puddles inside pens formed after the rainfall or by spill around drinking troughs, and small water courses and lagoons, formed by runoff). Nineteen (50·0%) strains harboured stx2a /stx2c genes, 18 (47·4%) stx2c and one stx1a /stx2c . All strains harboured eae, ehxA, rfbO157 and fliCH7 genes, and the putative virulence determinants ECSP_0242, ECSP_2687 and ECSP_3620. All isolates tested as Lineage I/II by lineage-specific polymorphism assay-6. Nineteen (50%) belonged to the high virulent clade 8. The q21 allele was found in all strains and q933 /q21 alleles in 17 (44·7%). By XbaI-pulsed-field gel electrophoresis, 29 strains were grouped into seven clusters. Four clusters grouped isolates from distant places separated by 150-250 km. This may be related to vectors, like birds, involved in their spread. Otherwise, three clusters contained isolates recovered at same places with intervals of 1-9 months. This could be explained by the high environmental persistence of STEC O157:H7. These strains recovered from surface water showed similar genotypes to those found in the bovine reservoir and in human diseases, and could be linked to the high incidence of haemolytic uremic syndrome in Argentina. SIGNIFICANCE AND IMPACT OF THE STUDY: The challenge for the growing global demand for food is to find sustained production strategies without collateral effects. Intensive livestock operations generate large volumes of manure that can contaminate a finite resource, the water. This study shows how water contaminated by confined feeding operations can transport dangerous pathogens and warns to pay more attention to control and sanitation systems to prevent this type of pollution.
Asunto(s)
Infecciones por Escherichia coli/veterinaria , Escherichia coli O157/aislamiento & purificación , Escherichia coli O157/patogenicidad , Factores de Virulencia/genética , Microbiología del Agua , Animales , Argentina , Bovinos , Electroforesis en Gel de Campo Pulsado , Infecciones por Escherichia coli/microbiología , Escherichia coli O157/genética , Genotipo , Síndrome Hemolítico-Urémico/microbiología , Humanos , Salud Pública , AguaRESUMEN
Cystic echinococcosis caused by Echinococcus granulosus sensu lato is one of the most important helminth zoonoses in the world; it affects both humans and livestock. The disease is endemic in Argentina and highly endemic in the province of Neuquén. Considerable genetic and phenotypic variation has been demonstrated in E. granulosus, and ten different genotypes (G1-G10) have been identified using molecular tools. Echinococcus granulosus sensu lato may be considered a species complex, comprised of E. granulosus sensu stricto (G1-G3), E. equinus (G4), E. ortleppi (G5) and E. canadensis (G6-G10). In endemic areas, the characterization of cystic echinococcosis molecular epidemiology is important in order to apply adequate control strategies. A cut-off value for larval large hook total length to distinguish E. granulosus sensu stricto isolates from those produced by other species of the complex was defined for the first time. Overall, 1780 larval hooks of 36 isolates obtained from sheep (n= 11, G1), goats (n= 10, G6), cattle (n= 5, G6) and pigs (n= 10, G7) were analysed. Validation against molecular genotyping as gold standard was carried out using the receiver operating characteristic (ROC) curve analysis. The optimum cut-off value was defined as 26.5 µm. The proposed method showed high sensitivity (97.8%) and specificity (91.1%). Since in most endemic regions the molecular epidemiology of echinococcosis includes the coexistence of the widely distributed E. granulosus sensu stricto G1 strain and other species of the complex, this technique could be useful as a quick and economical tool for epidemiological and surveillance field studies, when fertile cysts are present.