A study was carried out in the Castilla y León region of Spain to investigate the presence of Escherichia coli O157:H7 in raw ewe's milk samples collected from several cheese factories during 1 year. All specimens were examined for E. coli O157:H7 by selective enrichment at 41.5 ± 1.0°C, after both 6 and 22 h of incubation, and then immunomagnetically separated and plated on cefixime–potassium tellurite–sorbitol MacConkey agar. No growth was obtained in the enrichment broth after a 6-h incubation. Presumptive colonies obtained after 22 h of incubation were screened by a multiplex PCR assay for the presence of rfbO157 and fliCH7 genes. Of all the ewe's milk samples studied, three were positive for E. coli O157:H7. The E. coli O157:H7 strains that were positive for the rfbO157 and fliCH7 genes were then analyzed by multiplex PCR for the presence of virulence genes (stx1, stx2, ehxA, and eaeA). All E. coli O157:H7 isolates were Shiga toxigenic and harbored additional genes related to virulence (ehxA and eaeA). The predominant Stx toxin type was stx2. These results demonstrate that raw ewe's milk used in cheesemaking may be sporadically contaminated with E. coli O157:H7 strains that are potentially pathogenic for humans.
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Research Article|
April 01 2006
Detection, Occurrence, and Characterization of Escherichia coli O157:H7 from Raw Ewe's Milk in Spain
IRMA CARO;
IRMA CARO
*
1Research Centre for Food Science and Technology, Autonomous University of Hidalgo State, Tulancingo, Hidalgo 43600, México
* Author for correspondence. Tel: Int-34-987-291120; Fax: Int-34-987-291284; E-mail: dhticc@unileon.es.
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VICTOR M. FERNÁNDEZ-BARATA;
VICTOR M. FERNÁNDEZ-BARATA
2Department of Food Hygiene and Food Technology, University of León, 24071 León, Spain
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ANA ALONSO-LLAMAZARES;
ANA ALONSO-LLAMAZARES
2Department of Food Hygiene and Food Technology, University of León, 24071 León, Spain
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M. ROSARIO GARCÍA-ARMESTO
M. ROSARIO GARCÍA-ARMESTO
2Department of Food Hygiene and Food Technology, University of León, 24071 León, Spain
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J Food Prot (2006) 69 (4): 920–924.
Article history
Received:
August 11 2005
Accepted:
November 01 2005
Citation
IRMA CARO, VICTOR M. FERNÁNDEZ-BARATA, ANA ALONSO-LLAMAZARES, M. ROSARIO GARCÍA-ARMESTO; Detection, Occurrence, and Characterization of Escherichia coli O157:H7 from Raw Ewe's Milk in Spain. J Food Prot 1 April 2006; 69 (4): 920–924. doi: https://doi.org/10.4315/0362-028X-69.4.920
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