RAPID PROTOCOL (5.25 H) FOR THE DETECTION OF ESCHERICHIA COLI O157:H7 IN RAW GROUND BEEF BY AN IMMUNO‐CAPTURE SYSTEM (PATHATRIX) IN COMBINATION WITH COLORTRIX AND CT‐SMAC ¹

Abstract

A same day protocol for the detection of Escherichia coli O157:H7 by Pathatrix (a novel immuno‐capture method) and Colortrix (a rapid ELISA test) was developed. This study indicated that Pathatrix system, which circulated the pre‐enriched (4.5 h) samples over paramagnet beads with antibodies (0.5 h), increased the concentration of E. coli O157:H7 by 1.2–2.6 log CFU/25 g in 0.5 h from enrichment broth (modified EC broth with novobiocin or buffered peptone water). Colortrix, a rapid ELISA system, was used to detect the pathogens in another 0.25 h. Excellent correlation (100%) between positive Pathatrix/Colortrix (5.25 h system) results and positive Pathatrix/plating method with cefixime tellurite sorbitol‐MacConkey agar, with initial concentration of 0.7 to 2.1 log CFU/25 g was obtained. This new protocol offers a significant benefit to the meat industry allowing compliance with a “test” and “hold” program for E. coli O157: H7 in ground beef.

Methods for Detecting EnterohaemorrhagicEscherichia Coliin Food

“…Wu et al (48) designed an efficient protocol to detect one E. coli O157:H7 cell in 25 g of raw ground beef in 5 h combining, after enrichment, an immunomagnetic bead system with an immunological test. This test gives results in less than 15 min after use of the immunomagnetic system, with detection limits of 0.3 and 0.2 log cfu/25 g, respectively, in mEC + n and in BPW.…”

“…They can use polyclonal or monoclonal antibodies and are classified as homogeneous when the antigen-antibody complex formed is directly measurable -agglutination reactions, immunodiffusion -and heterogeneous when the unbound antibody must be separated from the bound antibody using labeled reagents -sandwich assay ( Different type of assays have been developed to give rapid bacteria detection methods (47)(48)(49) such as immunofluorescence, immunocapture, enzyme immunoassay, biosensors, and automated immunoassay that are simple to use having all the reagents placed on strips ready-to-use. To obtain an effective method to detect low concentration of E. coli O157:H7, the flow cytometry using fluorescein-labeled affinity purified specific antibody together with IMS technique has been developed resulting useful in the detection of as few as 4 E. coli cells/g of ground beef in just 7 h of analysis.…”

Chromogenic Agar Medium for Detection and Isolation of Escherichia coli Serogroups O26, O45, O103, O111, O121, and O145 from Fresh Beef and Cattle Feces

“…First, there are no commercial IMS beads available for serogroups 045 and 0121. IMS has been shown to be an A 32 32 21 30 23 14 20 B 32 32 18 32 29 18 32 C 32 30 26 22 27 20 32 Total 96 effective and important tool for the isolation of STEC bacteria, especially E. coli 0157:H7 strains, from complex sample matrices, including bovine feces (19), soils (16), milk (27), and ground beef (2,33). Second, the background flora and/or other serogroups competed with each other either in the enrichment medium or on the chromogenic agar plate.…”

Trends and Perspectives of Biosensors for Food and Environmental Virology

“…Involvement of IMS with standard culture methods for food and environmental virology is found to be a sensitive approach that reduces the detection time (Jackson et al 1993). Automated IMS systems have great promise for isolating pathogens from various food systems including fresh salad (Prentice et al 2006), ground beef (Wu et al 2004), and potato products (Warren et al 2006). Other approaches such as buoyant density gradient centrifugation can also be successfully used for separation of viruses from food matrices before PCR amplification of nucleic acids (Fukushima et al 2007).…”