Non-O157:H7 Shiga Toxin Producing Escherichia coli in Bovine Rectums and Surface Water Streams on a Beef Cattle Farm in Argentina

The purposes of this study were to detect non-O157 Shiga toxin-producing Escherichia coli (STEC) in bovine rectums and water in a beef cattle farm in Argentina, and to determine the pathogenic potential of the circulating strains. During the study, 292 rectal swabs from healthy animals and 79 environmental water samples were collected. The rectal swabs and one loop of the Moore swabs, enriched in Escherichia coli broth for 24 h at 37°C, were streaked on MacConkey agar plates and incubated overnight at 37°C. The isolates were characterized by biochemical tests and serotyped. Nonmotile STEC strains were typed for their H-specific (fliC) antigens by polymerase chain reaction (PCR). Isolates were characterized by detection of stx1, stx2, and their variants, eae, ehxA, and saa genes. Macrorestriction fragment analysis by pulsed-field gel electrophoresis (PFGE) was performed using the PulseNet standardized protocol. From 371 samples analyzed, 36.6% of rectal swabs and 34.2% of water samples were non-O157 STEC-positive by PCR, and 110 strains from rectal swabs, but only three from water, were isolated. The strains were grouped into 24 different serotypes, from which, O103:[H2] (n = 12), O136:H12 (n = 8), O178:H19 (n = 8), and O103:NM (n = 5) were most prevalent, representing 29.2% of the isolates. Predominant genotypes were stx1/eae/ehxA (16.8%) and stx2/saa/ehxA (15.9%). PFGE analysis revealed 56 different patterns, with 65 strains grouped in 19 clusters of 100% similarity. Two STEC O124:H19 strains isolated from rectal swabs and water with a 5-month interval harbored the stx1/stx2/saa/ehxA genotype, and showed an indistinguishable PFGE profile. By comparison, some XbaI-PFGE patterns identified in the present study were identical to the profiles of strains isolated from human, food, and animal sources included in the Argentine PulseNet database. By PCR, similar non-O157 detection rates were found in rectal swabs and water. However, the methodology for water samples needs to be improved, since only three strains from the total number of positive samples were recovered.Fil: Tanaro, José Daniel. Universidad Nacional de Entre Ríos. Facultad de Bromatología; ArgentinaFil: Galli, Lucía. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; ArgentinaFil: Lound, Liliana Haydee. Universidad Nacional de Entre Ríos. Facultad de Bromatología; ArgentinaFil: Leotta, Gerardo Anibal. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; ArgentinaFil: Piaggio, Mercedes Carolina. Universidad Nacional de Entre Ríos. Facultad de Bromatología; ArgentinaFil: Carbonari, Claudia Carolina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; ArgentinaFil: Kinue, Irino. Escola Nacional de Saude Publica Sergio Arouca; BrasilFil: Rivas, Marta. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud "Dr. C. G. Malbrán"; Argentin

Prevalence of Escherichia Coli O157:H7 in surface water near cattle feedlots

Between April 2009 and July 2011, 311 surface water samples in 48 cattle feedlots distributed in an area of about 67,000 km2 were analyzed to examine the environmental dissemination of Escherichia coli O157:H7. Samples were taken inside and outside the pens, exposed and not exposed to runoff from corrals, near the feedlots. Two types of samples were defined: (1) exposed surface waters (ESW; n = 251), downstream from cattle pens; and (2) nonexposed surface waters (NESW; n = 60), upstream from cattle pens. By multiplex PCR, 177 (70.5%) ESW samples were rfbO157-positive, and 62 (24.7%) E. coli O157, and 32 (12.7%) Shiga toxin-producing E. coli (STEC) O157:H7 strains were isolated. In the NESW samples, 36 (60.0%) were rfbO157- positive, and 9 (15.0%) E. coli O157, and 6 (10.0%) STEC O157:H7 strains were isolated. These results showed that the environmental surface waters exposed to liquid discharges from intensive livestock operations tended to be contaminated with more STEC O157:H7 than NESW. However, no significant difference was found. This fact emphasizes the relevance of other horizontal routes of transmission, as the persistence of E. coli in the environment resulting from extensive livestock farming. By XbaIPFGE, some patterns identified are included in the Argentine Database of E. coli O157, corresponding to strains isolated from hemolytic uremic syndrome and diarrhea cases, food, and animals, such as AREXHX01.0022, second prevalent pattern in Argentina, representing 5.5% of the total database. In the study area, characterized by the abundance of waterways, pathogens contained in feedlot runoff could reach recreational waters and also contaminate produce through irrigation, increasing the potential dissemination of STEC O157:H7 and the risk of human infections. The control of runoff systems from intensive livestock is necessary, but other alternatives should be explored to solve the problem of the presence of E. coli O157 in the aquatic rural environment.Fil: Tanaro, José Daniel. Universidad Nacional de Entre Rios. Facultad de Bromatologia; ArgentinaFil: Piaggio, Mercedes Carolina. Universidad Nacional de Entre Rios. Facultad de Bromatologia; ArgentinaFil: Galli, Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Direccion Nacional de Instituto de Investigacion. Adm.nacional de Laboratorio E Instituto de Salud "dr.c.g.malbran". Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriologia; ArgentinaFil: Gasparovic, Alejandra M. C.. Universidad Nacional de Entre Rios. Facultad de Bromatologia; ArgentinaFil: Procura, Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Entre Rios. Facultad de Bromatologia; ArgentinaFil: Molina, Demián A.. Universidad Nacional de Entre Rios. Facultad de Bromatologia; ArgentinaFil: Vitón, Mauro. Universidad Nacional de Entre Rios. Facultad de Bromatologia; ArgentinaFil: Zolezzi, Gisella. Direccion Nacional de Instituto de Investigacion. Adm.nacional de Laboratorio E Instituto de Salud "dr.c.g.malbran". Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriologia; ArgentinaFil: Rivas, Marta. Direccion Nacional de Instituto de Investigacion. Adm.nacional de Laboratorio E Instituto de Salud "dr.c.g.malbran". Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriologia; Argentin