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Comparison of Assurance GDS® MPX ID for Top STEC with Reference Culture Methods for the Detection of E. coli Top 6 STEC; Direct Confirmation of Top 6 STEC from Isolation Plates and Determination of Equivalence of PickPen® and FSIS OctoMACS™ Concentration Protocols
- Source :
- Journal of AOAC INTERNATIONAL. 99:428-443
- Publication Year :
- 2016
- Publisher :
- Oxford University Press (OUP), 2016.
-
Abstract
- Assurance GDS® MPX ID for Top Shiga toxin-producing Escherichia coli (STEC; MPX ID) was validated according to the AOAC INTERNATIONAL Methods Committee Guidelines for Validation of Microbiological Methods for Foods and Environmental Surfaces as (1) a secondary screening method for specific detection of the Top 6 STEC serogroups (O26, O45, O103, O111, O121, and O145) in raw beef trim, raw ground beef, raw spinach, and on stainless steel; and (2) as a confirmatory method for the identification of pure culture isolates as Top 6 STEC. MPX ID is used in conjunction with the upfront BCS Assurance GDS MPX Top 7 STEC assay. This Performance Tested MethodSM validation has two main parts: Method Developer studies and the Independent Laboratory study. A total of 180 samples and controls were analyzed. Results showed that MPX ID had no statistically significant differences with the reference culture methods for the detection of Top 6 STEC in the food matrixes (raw beef trim, raw ground beef, and raw spinach) and environmental sponges (stainless steel) studied. Inclusivity/exclusivity studies were also conducted. One hundred percent inclusivity among the 50 Top 6 STEC serovars tested and 100% exclusivity for the 30 non-Top 6 STEC organisms tested were demonstrated. For validation of MPX ID as a confirmatory method for isolated colonies, all inclusivity and exclusivity organisms were streaked for isolation onto five STEC plating media: modified rainbow agar, Levine's eosin-methylene blue (L-EMB) agar, rainbow agar with novobiocin and cefixime, and enterohemolysin agar with selective agents as well as trypticase soy agar with yeast extract. These isolated colonies were suspended and analyzed by Assurance GDS MPX Top 7 STEC and MPX ID. MPX ID was able to correctly confirm all inclusivity organisms from all plate types, except two STEC isolates from L-EMB agar plates only in the Independent Laboratory study. All exclusivity organisms were correctly determined by MPX ID as non-Top 6 STEC from the STEC plating media. An additional but separate part of these studies was a comparison of immunomagnetic separation (IMS) efficiency using the Assurance GDS procedure with a PickPen® device and the U.S. Department of Agriculture procedure using the OctoMACS™ Separator device for plating onto chromogenic agar. Results demonstrated the equivalence of the two IMS procedures for plate confirmation of Top 7 STEC.
- Subjects :
- 0301 basic medicine
Serotype
Meat
food.ingredient
030106 microbiology
Biology
Immunomagnetic separation
Analytical Chemistry
Agar plate
03 medical and health sciences
chemistry.chemical_compound
food
Spinacia oleracea
Animals
Environmental Chemistry
Food microbiology
Agar
Trypticase soy agar
Food science
Pharmacology
Shiga-Toxigenic Escherichia coli
Immunomagnetic Separation
Stainless Steel
chemistry
Food Microbiology
Pure culture
Cattle
Agronomy and Crop Science
Food Analysis
Food Science
Primary screening
Subjects
Details
- ISSN :
- 19447922 and 10603271
- Volume :
- 99
- Database :
- OpenAIRE
- Journal :
- Journal of AOAC INTERNATIONAL
- Accession number :
- edsair.doi.dedup.....87f0dd93c0e0488b6f3d7591e27c4c61