ANSR® - A nicking enzyme amplification reaction for rapid detection of foodborne pathogens

ANSR® is an isothermal nucleic acid amplification technology developed for rapid detection of pathogenic bacteria in food and environmental samples.  The ANSR chemistry utilizes a specific DNA nicking enzyme and DNA polymerase to produce copies of target DNA sequence, which are detected in real time using molecular beacon probes.  RNA sequences are  targeted by addition of reverse transcriptase to the reaction mix.   ANSR^TM produces results within 30-50 minutes following sample enrichment and requires limited equipment.   The ANSR Salmonella assay  was shown to detect all but one of 109 serovars of S. enterica and S. bongori tested.  No cross-reactivity with any non-salmonellae was observed.  The limit of detection is 10³-10⁴ cfu/mL of enrichment culture.  In testing of 10 foods inoculated with low levels of sublethally-injured Salmonella spp., the ANSR method was found to be as sensitive as the reference FDA and USDA culture procedures.  The ANSR Listeria assay, targeting a genus-specific rRNA sequence, was found to detect the 6 common Listeria species, with no cross-reactivity with non-listeriae.  The limit of detection is ~ 10² cfu/mL.  The test was validated for detection of Listeria spp. in a variety of food types and found to be as productive as the FDA and USDA reference culture procedures.       

ANSR®  can also be utilized as a confirmation tool from a colony pick.  Pre-collaborative and collaborative studies were conducted to assess the inclusivity and exclusivity characteristics of the test from a variety of selective/differential agar media, and to evaluate performance of the test in a multi-laboratory trial.  Accuracy with inclusivity and exclusivity strains was 99.1% and 98.8% and 99.9% and 96.5% in the precollaborative and collaborative studies respectively.  Based on these data, the method has been granted AOAC Official Method status (method 2013.14). 

ANSR® provides food testing laboratories a rapid, simple solution for pathogen analysis and confirmation.