AOAC 133rd Annual Meeting - Final Program

Poster Abstracts | Wednesday

P-W-073 Charlotte Cooper , Katharine Evans , David Crabtree , Annette Hughes , Jessica Williams , Thermo Fisher Scientific, Basingstoke, United Kingdom Superior Detection of Multiple Salmonella Serovars from Meat and Environmental Samples Using a Multiplex PCR Method Salmonella is a common meat contaminant, posing a public health threat. Foods can be contaminated with multiple Salmonella serovars but limitations in standard reference meth- ods may mean only one is confirmed, leading to low accuracy in monitoring of prevalence. The purpose of the studies was to compare co-infection detection capabilities of the Thermo Scientific™ RapidFinder™ Salmonella species, Typhimurium and Enteritidis Multiplex PCR Kit versus ISO and FSIS MLG methods. Fifty-eight samples of 25 g, including pork, poultry and production environment samples, were dual-infected with S . Typhimurium or S . Enteritidis and another Salmonella sero- var. Samples were split equally between the candidate method and ISO 6579-1:2017, and tested alongside 29 unspiked samples per method. In a second unpaired study, 50 samples of 25 g of raw pork sausage were triple-infected with S . Ohio, S. Typhimurium and S . Enteritidis. Samples were split equally between the candidate method and FSIS MLG 4.09, and tested alongside 20 unspiked samples. In the dual-infection study, the candidate and ISO methods detected 21 (72.4%) and 11 (37.9%) co-infected samples respectively. In the triple-infection study, the candidate method detected 12 triple-infected samples while FSIS confirmed one. These studies show the superior detection of Salmonella co-infection by the candidate method versus standard methods, facilitating improved reporting of key Salmonella serovars Typhimurium and Enteritidis. Presenter: Jessica Williams, Thermo Fisher Scientific, Basingstoke, United Kingdom, Email: jessica.williams@thermofisher.com P-W-074 Dean Leak , Jessica Williams , Charlotte Cooper , David Crabtree , Thermo Fisher Scientific, Basingstoke, United Kingdom Improved Confirmation of STEC Contaminants Using the Thermo Scientific™ SureTect™ E. coli O157:H7 and STEC Screening and Identification PCR Assay Food samples high in background microflora pose a challenge for shiga-toxin producing E. coli (STEC) confirmation testing; suspect positives from PCR analysis can remain unconfirmed due to difficulties in isolation of the target organism. An improved protocol could enable STEC to be easily and accurately confirmed, leading to more precise reporting. These studies assessed performance of the Thermo Scientific™ SureTect™ E. coli O157:H7 and STEC Screening and Identification PCR Workflow confirmation method using Thermo Scientific™ Chromogenic Colifrom Agar (CCA) and compared it with confirmation using an alternative plating medium: CHROMagar™ STEC. Thirty-six “Big Six” STEC strains were streaked onto CCA and CHROMagar™ . Plates were incubated at 37°C for 18 hours and the inclusivity of both plating media compared. In a second study, ten vegetable samples with high levels of microflora were spiked with STEC at 0.67-1.79 CFU/25 g and enriched alongside two unspiked samples with the same microflora. These were confirmed via the

SureTect™ confirmation protocol. In the SureTect™ confirmation study, CCA facilitated typical growth for 34 (94.4%) strains, while CHROMagar™ partially or fully inhibited 18 (50%) strains. In the vegetable study, the candidate method confirmed six STEC isolates despite high background growth. These data sets demonstrate the effectiveness of the SureTect™ confirmation plating method, enabling highly contaminated STEC samples to be confirmed rapidly and reliably. Presenter: Jessica Williams, Thermo Fisher Scientific, Basingstoke, United Kingdom, Email: jessica.williams@thermofisher.com P-W-075 Jessica Williams , Simon New , David Crabtree , Agata Dziegiel , Annette Hughes , Thermo Fisher Scientific, Basingstoke, United Kingdom Multiplex PCR for Detection and Differentiation of Campylobacter jejuni , Campylobacter coli , and Campylobacter lari from Poultry Matrices in Less Than 24 Hours Campylobacter jejuni, Campylobacter coli and Campylobacter lari from contaminated poultry are causative agents of campy- lobacteriosis, an invasive infection resulting in 1.3 million cases in the United States annually. It is difficult to differentiate these Campylobacter species due to similar 16s rRNA sequences and phenotypic properties. Here we report a new Thermo Scientific™ SureTect™ real-time, multiplex PCR assay that can reliably differentiate C. jejuni , C. coli and C. lari from poultry matrices with a turnaround time of less than 24 hours in a single reaction. A total of 132 samples were used in the study. 103 samples were used to test inclusivity and exclusivity of the new assay versus the BAX ® System Real-Time PCR Assay for Campylobacter. A total of 28 poultry samples including carcass rinses, raw meat with skin and ready to re-heat meat were spiked with Campylobacter isolates, enriched for 22 hours and again tested via PCR. The new assay demonstrated 100% inclusivity for all three Campylobacter targets. Inclusivity of the BAX ® Campylobacter assay was 100, 84, and 42% for C. jejuni , C. coli and C. lari , respectively. Exclusivity of both assays was 100%. All three target species were recovered after 22 hours enrichment from the poultry matrices. The solution described offers an improvement in both accuracy and workflow efficiency when screening for Campylobacter jejuni, C. coli and C. lari from poultry matrices. Presenter: Jessica Williams, Thermo Fisher Scientific, Basingstoke, United Kingdom, Email: jessica.williams@thermofisher.com P-W-076 Jessica Williams , Charlotte Cooper , David Crabtree , Dean Leak , Thermo Fisher Scientific, Basingstoke, United Kingdom Rapid STEC Detection from Beef Using the Thermo Scientific™ SureTect™ E. coli O157:H7 and STEC Screening and Identification PCR Assay Beef is at high risk of shiga-toxin producing Escherichia coli (STEC) contamination due to the organism’s commensal nature in ruminants. International standard reference methods for STEC detection can be time-consuming and use enrichment protocols that are not fully harmonized with those for other key meat contaminants such as Salmonella . A faster, harmonised

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