title: 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.
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 Method(SM) 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.
authors.affiliation: BioControl Systems, Inc., 12822 SE 32nd St, Bellevue, WA 98005, USA.
authors.forename: Philip
authors.initials: P
authors.lastname: Feldsine
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Lienau
authors.forename: Khyati
authors.initials: K
authors.lastname: Shah
authors.forename: Amy
authors.initials: A
authors.lastname: Immermann
authors.forename: Khanh
authors.initials: K
authors.lastname: Soliven
authors.forename: Mandeep
authors.initials: M
authors.lastname: Kaur
authors.forename: David E
authors.initials: DE
authors.lastname: Kerr
authors.forename: Markus
authors.initials: M
authors.lastname: Jucker
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5100 Paint Branch Pkwy, College Park, MD 20740, USA.
authors.forename: Tom
authors.initials: T
authors.lastname: Hammack
authors.affiliation: Brodsky Consultants, 73 Donnamora Crescent, Thornhill, ON L3T 4K6, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Brodsky
authors.affiliation: Q Laboratories, Inc., 1400 Harrison Ave, Cincinnati, OH 45214, USA.
authors.forename: James
authors.initials: J
authors.lastname: Agin
mesh_terms: D000818:Animals; D002417:Cattle; D005504:Food Analysis; D005516:Food Microbiology; D018189:Immunomagnetic Separation; D008460:Meat / Q000382:microbiology; D054323:Shiga-Toxigenic Escherichia coli / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification*; D018724:Spinacia oleracea / Q000382:microbiology; D013193:Stainless Steel
chemical_list: D013193:Stainless Steel