HOME > EDICIONES > Año 2006, Volumen 56 - Número 3
Trabajos de Investigación
Evaluación de la técnica de inmunoseparación magnética para recuperación de Escherichia coli O157:H7 en cremas de leche
Tomás Rojas, Ysvette Vásquez, Doris Reyes, Carlos Martínez, Luís Medina
Unidad de Microbiología Ambiental, Departamento de Microbiología, Facultad de Ciencias de la Salud, Universidad de Carabobo, Venezuela, Laboratorio de Bacteriología, Hospital Estadal los Samanes, Maracay, Edo Aragua, Venezuela
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SUMMARY
Evaluation of the technique of immunomagnetic separation for recovery of Escherichia coli O157:H7 in milk creams
The utility of immunomagnetic separation (IMS) for the recovery of Escherichia coli O157:H7 in milk creams was evaluated. The efficiency of different pre-enrichments broths previous to ISM was determined and different agars were analyzed (differential and/or selective) for plating of the inmunobeads. Portions of 25 g from milk creams were inoculated with pathogen low levels (50, 10 and 1 cell/g) and then, were enriched in buffered peptone water with vancomycin (BPW-V), buffered peptone water with vancomycin and cefixime (BPW-VC) and triptone soya broth with vancomycin, cefixime and tellurite (TSB-VCT) being incubated 35ºC/18 hours. Then, IMS was applied and immunobeads were plated onto sorbitol MacConkey agar (SMA), sorbitol MacConkey agar with cefixime and tellurite (SMA-CT) and chromogenic agar with tellurite and cefixime (CRGA-TC). It was observed significant differences (p<0,05) in the recovery percentages according to the pre-enrichment broth used, being obtained the biggest recovery rates with the use of TSB-VCT for the three inocula levels. The recovery rates did not vary significantly (p<0,05) among the utilized agars, while the number of inoculated cells impacts the recovery percentages, being bigger as it increases the inocula. In conclusion, IMS is a sensitive method for the recovery of Escherichia coli O157:H7 in milk creams, recommending for isolation of this pathogen, the enrichment in TSB-VCT, application of IMS, and plating of immunobeads onto nonselective agar (SMA) and selective agar (SMA-TC or CRGA-TC).
Key words: Escherichia coli O157:H7, immunomagnetic separation, dairy products.
Recibido: 25/04/2006
Aceptado: 14/08/2006
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PRIVACIDAD | ACCESIBILIDAD
ALAN-VE ISSN 0004-0622 - Depósito Legal: pp 199602DF83
Sociedad Latinoamericana de Nutrición
Producción editorial en Venezuela: Capítulo Venezolano - RIF: J-30843129-0
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