ISO 16654 - Searching for Escherichia coli O157

ISO 16654: Microbiology of food and animal feeding stuffs — Horizontal method for the detection of Escherichia coli 0157

Searching for Escherichia coli O157 for human consumption or animal feed by horizontal method is carried out within the scope of the “ISO 16654” standard. Escherichia coli O157 definition within the scope of ISO 16654 standard: Microorganisms that form typical colonies on the surface of the plating medium used in the standard, produce indole, and are agglutinated with antiserum, especially against the O157 antigen.

Principle of Analysis
Detection of Escherichia coli O157 under ISO 16654 is carried out in four steps:
a) 41.5 °C ± 1 °C' Enrichment of the homogenized test portion in modified tryptone soybean broth containing novobiocin (mTSB + N) by incubation for 6 hours followed by 12 hours - 18 hours.
b) Microorganisms through immunomagnetic particles coated with antibodies against E. coli O157 separation and concentration.
c) Isolation by subculture of immunomagnetic particles with adherent bacteria on CT-SMAC (Cefixime tellurite sorbitol MacConkey agar) and the user's choice of a second selective isolation agar.
d) sorbitol from CT-SMAC -confirmation of negative colonies and typical E. coli O157 colonies on second isolation agar by indole production and agglutination with E. coli O157 antiserum.

Normative Standards
ISO 6887- 1, Microbiology of food and animal feed - Preparation of test samples for microbiological examination, initial suspension and decimal dilutions - Part 1: General rules for the preparation of initial suspension and decimal dilutions.
ISO 7218, Microbiology of food and animal feed - For microbiological studies general rules.

You can contact Nanolab Food Analysis Laboratory for the detection of Escherichia coli 0157 in food and feed.