Australian implementation of NeoSeek for molecular detection and confirmation of Shiga toxin producing Escherichia coli

Summary

Australian meat samples for export to the United States of America are required to undergo microbiological testing for certain Escherichia coli strains that can cause disease in humans. E. coli that produce Shiga toxins (stx) are termed Shiga toxigenic E. coli (STEC). E. coli O157:H7 was the first STEC required by the US for export testing in 2007, however an additional six serogroups, including O26, O45, O103, O111, O121 and O145 (commonly referred to as non-O157) were added to testing requirements in 2012.

NeoSeek is a multiplexed polymerase chain reaction (PCR) of 89 targets followed by analysis of Matrix assisted laser desorption ionisation - time of flight (MALDI-TOF) mass spectrometry of the PCR products to determine the presence of harmful Shiga toxin-producing Escherichia coli.

This project achieved site acceptance testing of the NeoSeek testing protocol, verification of laboratory quality systems and production of data on Australian samples that will further enable the Australian industry to make informed choice of testing method.

Objectives

This project aimed to determine that the NeoSeek service in Gatton:

• meets the precision, specificity, and accuracy previously attained in the Lincoln, NE USA laboratory
• meets proficiency requirements
• is added to the ISO 17025 accreditation scope
• completes an application to AOAC for acceptance of the method as a screening test
• completes an application to DAWR for acceptance of the method for export purpose
• is compared in performance to common testing methods used in Australia.

Key findings

• The NeoSeek technology develops a genetic profile for bacteria in a meat sample and then compares those results with the known genetic makeup of the reference E. coli strains to identify and differentiate the target strains.
• NeoSeek assays more than 86 specific genetic markers to provide faster results than conventional culture methods.
• The NeoSeek STEC test has received AOAC approval (#081901) and is an accepted method in the US with FSIS.
• NeoSEEK will be offered in Australia as both a screening test (NeoSEEK Screen) and a confirmation test (NeoSEEK Confirm).
• The screening test will have a 24 hour turnaround, as will the confirmation. 
• If the screening test has been performed with NeoSEEK, then the confirmation results can be processed within 2 hours. If the test is screened elsewhere and run on NeoSeek Confirm, the results can be processed in 24 hours. 

Benefits to industry

Of most value to the Australian meat export industry is a test that is able to minimize the amount of PP samples, whilst maintaining a high power of discrimination in detecting STEC samples. NeoSeek STEC can be run as a single-step confirmatory method, with a proven high rate of accuracy and low rate of false potential positives.

MLA action

MLA will take opportunities to inform processor laboratories about this new option for testing.