ABSTRACT
Escherichia coli productor de toxina Shiga (STEC) es el patógeno emergente en alimentos de mayor impacto, siendo su principal reservorio el ganado bovino. STEC puede causar diarrea, colitis hemorrágica y síndrome urémico hemolítico. El presente trabajo estudió la acción citotóxica de dos cepas de STEC aisladas de heces de terneros diarreicos en colon humano in vitro. Los fragmentos se montaron como un diafragma en una cámara de Ussing y se incubaron con las cepas patógenas. El flujo neto absortivo de agua (Jw) disminuyó y la corriente de cortocircuito (Isc) aumentó significativamente (P < 0,01) con respecto al control negativo. Los tejidos presentaron erosión de la mucosa, exfoliación del epitelio, y presencia de pseudomembranas en el lumen. A nivel de la lámina propia se observaron lesiones circulatorias leves. Una moderada infiltración de neutrófilos se observó en el lumen y en las células epiteliales. Las criptas colónicas no se vieron afectadas. El grado de lesión fue similar en ambas cepas experimentales. Este es el primer estudio que demuestra que cultivos de cepas de STEC aisladas de ganado bovino producen efectos citotóxicos en colon humano in vitro.
Shiga toxin-producing E. coli (STEC) is one of the most important emergent pathogen in foods, being its main reservoir bovine cattle. STEC can cause diarrhea, hemorrhagic colitis and hemolytic-uremic syndrome. The present work have studied the cytotoxic action in human colon of cultures of two STEC strains isolated from faeces of calves with bloody diarrhea. Colonic mucosa was mounted as a diaphragm in a Ussing chamber and incubated with the cultures of pathogenic strains. Net water flow (Jw) decreased and the short-circuit current (Isc) increased significantly (p < 0,01) compared to negative control. Tissues showed an erosion of the mucose, epithelial exfoliation, and presence of pseudo-membranes in the lumen. Mild circulatory lesions were observed in the lamina propia. A moderate neutrophils infiltration was observed in the lumen and into the epithelial cells. Colonic crypts were not disrupted. Both experimental strains caused a similar lesion on colon tissues. This is the first study that shows that cultures of STEC strains isolated from bovine cattle produce cytotoxic effects in vitro in human colon.
Subject(s)
Animals , Cattle , Humans , Cattle Diseases/microbiology , Colon/microbiology , Diarrhea/veterinary , Escherichia coli Infections/veterinary , /pathogenicity , In Vitro Techniques , Intestinal Mucosa/microbiology , Biological Transport , Body Water/metabolism , Colon/metabolism , Colon/pathology , Diarrhea/microbiology , Epithelial Cells/metabolism , Epithelial Cells/microbiology , Epithelial Cells/pathology , Escherichia coli Infections/microbiology , /isolation & purification , /physiology , Intestinal Mucosa/metabolism , Intestinal Mucosa/pathology , Neutrophils/pathology , Species Specificity , VirulenceABSTRACT
Thirty-five samples of eviscerated poultry from processing plants in greater Buenos Aires were examined for the presence of Salmonella. Eighteen samples (51.2
) were found to be contaminated with salmonellae on testing with the non-destructive rinse method. Out of 7 plants investigated, 6 exhibited the presence of Salmonella in the product. A total of 6 confirmed species were found, S. infantis being the most frequently isolated. Rappaport-Vassiliadis and Tetrathionate-Brilliant Green broths were used as enrichment media, combined with Bismuth Sulphite or Brilliant Green-Phenol Red-Lactose-Sucrose-Deoxycholate agars as isolations media. The combination Rappaport-Vassiliadis broth and Bismuth Sulphite agar, was the only one that allowed the detection of all positive samples, including the six confirmed Salmonella species. Taking in to account the percentage of presumed colonies that were later confirmed, the Rappaport-Vassiliadis broth/Bismuth Sulphite agar proved the most specific.