A Comparative Evaluation of the Invisible Sentinel Campylobacter Assay for the Detection of Campylobacter Species in Chicken Carcass Rinsates

Introduction: The Invisible Sentinel (IS) Campylobacter assay is a molecular-based test designed to detect the presence of Campylobacter jejuni and Campylobacter coli from chicken carcass rinsates, after 24 hours of enrichment, without the need for growth in a specialized anaerobic chamber. The assay utilizes a PCR-based detection method coupled with a rapid vertical flow-based assay and eliminates the need for gel electrophoresis or fluorophore-based analysis of target amplification. This new method provides the specificity and sensitivity of PCR-based amplification in a cost-efficient and easy-to-use format with presumptive results in as little as 26 hours.

Purpose: The purpose of this independent evaluation was to compare the new method to the USDA/FSIS-MLG 41.01 for chicken carcass rinsates and conduct Inclusivity and Exclusivity testing as part of the AOAC Research Institute™ validation process.

Methods: The method comparison analyzed two lots of chicken carcass rinsate for the presence of naturally occurring Campylobacter species. For the new method, chicken carcasses were rinsed and enriched with IS Bolton’s Broth.  After incubation, samples were lysed and the target DNA was amplified using a thermocycler.  The amplified DNA was mixed with a proprietary buffer, transferred to a cassette and results were obtained.  Samples were confirmed following procedures outlined in the USDA/FSIS-MLG.  For the inclusivity and exclusivity evaluation, 50 Campylobacter isolates and 30 closely related non-Campylobacter isolates were evaluated.

Results: A POD statistical analysis indicated no significant differences observed between the new method and the reference method. For inclusivity, 50 out of 50 strains of Campylobacter species (38 Campylobacter jejuni and 12 Campylobacter coli) were correctly identified.  All 30 exclusivity organisms were correctly excluded.  

Significance: This new method demonstrated reliability as a rapid qualitative method for the detection of Campylobacter species in chicken carcass rinse.