ศูนย์นวัตกรรมเทคโนโลยีหลังการเก็บเกี่ยว

Isolation and characterization of Shiga toxin-producing Escherichia coli O157:H7 and non-O157 from beef carcasses at a slaughter plant in Mexico

J.J. Varela-Hernández, E. Cabrera-Diaz, M.A. Cardona-López, L.M. Ibarra-Velázquez, H. Rangel-Villalobos, A. Castillo, M.R. Torres-Vitela and A. Ramírez-Álvarez

International Journal of Food Microbiology, Volume 113, Issue 2, 25 January 2007, Pages 237-241

2007

บทคัดย่อ

The contamination of beef carcasses with Shiga toxin-producing O157:H7 and non-O157 Escherichia coli (STEC) obtained from a slaughter plant in Guadalajara, Mexico was investigated. A total of 258 beef carcasses were sampled during a 12-month period. All samples were assayed for STEC by selective enrichment in modified tryptone soy broth supplemented with cefixime, cefsulodin and vancomycin, followed by plating o­n Sorbitol MacConkey Agar supplemented with cefixime and tellurite (CT–SMAC). Simultaneously, all samples were assayed by immunomagnetic separation (IMS) and plated o­n CT–SMAC and CHROMagar®. The presence of the stx1, stx2, eaeA and hly₉₃₃ genes, recognized as major virulence factors of STEC, was tested for O157:H7 and non-O157 E. coli isolates by multiplex polymerase chain reaction (PCR). STEC was detected in two (0.8%) samples. o­ne of these STEC isolates corresponded to the serotype O157:H7 showing stx2, eaeA and hyl₉₃₃ genes. The other isolate corresponded to non-O157 STEC and o­nly had the stx1 gene. Thirteen carcasses (5%) were positive for nonmotile E. coli O157 and 7 (2.7%) were positive for E. coli O157:H7. The presence of O157:H7 and non-O157 STEC o­n beef carcasses in this slaughter plant in Guadalajara, Mexico, emphasizes the importance of implementing the Hazard Analysis and Critical Control Point (HACCP) system, as well as the need for implementing, evaluating, and validating antimicrobial interventions to reduce the presence of potential pathogenic microorganisms.

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