Evaluation of the 3M™ Petrifilm™ Rapid E. coli/Coliform Count Plate for the Enumeration of E. coli and Coliforms: Collaborative Study, First Action: 2018.13.

BACKGROUND: The 3M™ Petrifilm™ Rapid E. coli/Coliform Count Plate is a selective and differential sample-ready-culture medium designed for the rapid enumeration of Escherichia coli (E. coli) and coliforms in the food and beverage industries. OBJECTIVE: The 3M Petrifilm Rapid E. coli/Coliform Count Plate was compared to the U.S. Food and Drug Administration Bacteriological Analytical Manual (BAM) Chapter 4 Enumeration of Escherichia coli and the Coliform Bacteria, the International Organization of Standards (ISO) 4832:2006 Microbiology of food and animal feeding stuffs - Horizontal method for the enumeration of coliforms-Colony-count technique, and ISO 16649-2:2017 Microbiology of food and animal feeding stuffs-Horizontal method for the enumeration of beta-glucuronidase-positive Escherichia coli-Part 2 Colony-count technique at 44 degrees C using bromo-4-chloro-3- indolyl beta-D-glucuronide methods for the enumeration of E. coli and coliforms in dry dog kibble. METHOD: The candidate method was evaluated using two diluents, Butterfield's phosphate buffered diluent and peptone salt solution, in a paired study design with each reference method in a multi-laboratory collaborative study following the current AOAC Validation Guidelines. Three target contamination levels and an uninoculated control level were evaluated. RESULTS: The candidate and reference methods were not statistically different at each contamination level. Reproducibility values obtained during the collaborative study were similar between the candidate and reference methods. CONCLUSION: These results demonstrate that the candidate method is equivalent to the reference methods. HIGHLIGHT: 3M Petrifilm Rapid E. coli/Coliform Count Plate was recommended for Official First Action status for enumeration of E. coli and coliforms in a broad range of foods and environmental surfaces.

Validation of the Reveal® 3-D for Peanut Lateral Flow Test: AOAC Performance Tested MethodSM 111901.

BACKGROUND: Reveal® 3-D for Peanut is an immunochromatographic, lateral flow test for qualitative detection of peanut residue in food manufacturing and food preparation settings. The test can detect low ppm levels of peanut in clean-in-place (CIP) rinses and in swabs from environmental surfaces and can serve as a tool in managing allergen risk. OBJECTIVE: The objective of the study was to validate the lateral flow method for detection of peanut in CIP rinses, specifically water, peroxyacetic acid/hydrogen peroxide, and quaternary ammonium compound rinses, and in swabs taken from stainless steel and plastic surfaces. METHODS: CIP rinses spiked with low levels of peanut were tested, as were surfaces inoculated with peanut. Specificity and assay interference were assessed in testing of food commodities with and without added peanut. Assay robustness and test kit stability and consistency testing were also performed. RESULTS: Results demonstrated that the lateral flow test can detect peanut in CIP rinses in the range of 2-4 ppm and in environmental surface swabs in the range of 3-4 µg/100 cm2. Results of specificity testing with 29 common food items showed lack of cross-reactivity, and potential assay interference only from walnut. Data from stability trials supports expiration dating for the kit of up to 23 months post-manufacture. CONCLUSIONS AND HIGHLIGHTS: The lateral flow test is a sensitive, specific, and rapid method for detection of low levels of peanut residue in CIP rinses and environmental samples and can be an important component in a comprehensive allergen risk management program.

Evaluation of the CERTUS Environmental Listeria Species Detection Kit for the Detection of Listeria Species on Environmental Surfaces: AOAC Performance Tested MethodSM 101802.

BACKGROUND: CERTUS Environmental Listeria species Detection Kit (CERTUS EL Detection Kit) is a real-time, bio-contained assay designed to accurately detect Listeria species (L. grayi, L. innocua, L. ivanovii, L. marthii, L. monocytogenes, L. seeligeri, and L. welshimeri) from environmental surface matrixes using an antibody-coupled magnetic microparticle with a Surface Enhanced Raman Spectroscopy (SERS) nanoparticle technology test system paired with proprietary CERTUS EL Selective Growth Media and CERTUS Detection Unit. OBJECTIVE: The method was evaluated for AOAC®Performance Tested MethodSM certification. METHODS: Inclusivity and exclusivity, matrix studies, product consistency and stability were conducted to evaluate the CERTUS EL Detection Kit. RESULTS: In the matrix studies, stainless steel, ceramic tile, plastic (polystyrene) and sealed concrete environmental surfaces (4 × 4" test areas) were tested. No statistically significant differences were found by Probability of Detection analysis (POD) in any of the matrixes when results were compared to the U.S. Food and Drug Administration cultural microbiology reference method for Listeria. The CERTUS EL Detection Kit correctly identified all 50 target Listeria isolates and correctly excluded all 30 non-target strains that were analyzed. Probability of Detection analysis of CERTUS EL Detection Kit robustness, product consistency (lot-to-lot) and stability studies demonstrated no statistically significant differences, and no variation was observed between instruments. CONCLUSIONS: The data collected in these studies demonstrate that the CERTUS EL Detection Kit is a reliable method for the rapid and specific detection of Listeria from stainless steel, ceramic tile, plastic (polystyrene) and sealed concrete environmental surfaces.

Evaluation of the MC-Media Pad® Rapid Aerobic Count Device for the Enumeration of Total Aerobic Counts in a Variety of Foods: Collaborative Study, First Action Official MethodSM 2019.02.

BACKGROUND: The MC-Media Pad® Rapid Aerobic Count (RAC) is a ready-to-use culture device combining a test pad coated with medium and water absorption polymers that are designed for the rapid quantification of total aerobic bacteria in food products. OBJECTIVE: The MC-Media Pad RAC was compared to the U.S. Department of Agriculture Food Safety and Inspection Service Microbiology Laboratory Guidebook, Chapter 3.02: Quantitative Analysis of Bacteria in Foods as Sanitary Indicators for raw ground pork and the Standard Methods for the Examination of Dairy Products, Chapter 6: Microbial Count Methods for yogurt drink. METHOD: The candidate method was evaluated against the reference methods using a paired study design in a multi-collaborator study, following the current AOAC INTERNATIONAL Official Methods of AnalysisSM Appendix J guidelines. Three target contamination levels (low, medium, and high) were evaluated. MC-Media Pad RAC devices were enumerated after 24 and 48 h of incubation. RESULTS: Plate counts obtained by both methods were log10-transformed and the difference of means (including 95% confidence intervals), repeatability SD, and reproducibility SD were determined for each contamination level. All 95% confidence intervals for mean difference fell easily within ±0.10, the performance requirement being ±0.5. CONCLUSION: The MC-Media Pad RAC (for both 24 and 48 h) and both reference methods for each contamination level were therefore shown to be equivalent, with 97.5% confidence. HIGHLIGHTS: The new method offers a convenient alternative to the reference methods for detection of aerobic plate count in food products, yielding reliable and comparable results in 24 or 48 h compared to 48 h for the reference methods.

BL30SEC Method for Detection of Beta-Lactams in Raw Commingled Cow Milk: AOAC Performance Tested MethodSM 061902.

Testing milk for antibiotics before acceptance into dairies is required by the U.S. Pasteurized Milk Ordinance. Technological advances in tests have reduced screening times and improved detection accuracy. This work describes the validation of the Charm Rapid One Step Assay Beta-Lactam 30 Second Test according to the U.S. Food and Drug Administration Center for Veterinary Medicine protocol for raw commingled milk. Milk is added to the lateral flow test strip in an incubator/reader to deliver a 30 second result. Independent laboratory validation followed sensitivity, interference, and incurred residue protocols. Sensitivity, in parts per billion (ppb = µg/kg), using a probit curve determined 90% percent detection with 95% confidence, which met National Conference of Interstate Milk Shipments (NCIMS) specifications. Six U.S. approved beta-lactam drugs were detected below, but within 50% of, target/tolerance levels for penicillin G 2.9 ppb, ampicillin 5.9 ppb, amoxicillin 5.8 ppb, cephapirin 13 ppb, cloxacillin 8.1 ppb, and ceftiofur metabolites 73 ppb. No interferences were observed from 33 animal drugs at 100 ppb, somatic cells at 1.2 million/mL, or bacterial levels of >300 000 CFU/mL. Incurred residue detection levels were similar to levels determined with the spiked parent compound. The data support NCIMS that the BL30SEC method met U.S. criteria for testing milk for beta-lactams.

Modification of the Bio-Rad iQ-Check Listeria spp. Kit for the Detection of Listeria Species in Environmental Surfaces.

BACKGROUND: The Bio-Rad iQ-Check Listeria spp. Kit uses real-time PCR technology for detection of Listeria species in select food matrixes and environmental surfaces. OBJECTIVE: The iQ-Check Listeria spp. method was modified to reduce the enrichment medium volume for environmental sponges from 225 and 100 to 60 mL and to reduce the enrichment time for sponges and swabs from 25 ± 1 to as short as 18 h. The modified method was validated with stainless steel, polystyrene plastic, and sealed concrete using sponges or swabs with two different neutralizing buffers (Letheen Broth and HiCap™ Neutralizing Broth). In addition, the Bio-Rad Free DNA Removal Solution was used for all environmental samples. METHODS: The iQ-Check Listeria spp. modified method was compared with the reference culture method in the U.S. Department of Agriculture Food Safety and Inspection Service Microbiology Laboratory Guidebook Chapter 8.10 using an unpaired study design. RESULTS: In the method comparison study, the iQ-Check Listeria spp. modified method demonstrated no statistical difference in performance between candidate and reference method results or between presumptive and confirmed results for all environmental surfaces analyzed using HiCap Neutralizing Broth (World Bioproducts LLC) and Letheen broth. CONCLUSIONS: The modified iQ-Check Listeria spp. method is an effective method for the detection of Listeria species in environmental surfaces using both types of neutralizing buffer. HIGHLIGHTS: The method modification was granted based on the data collected.

Matrix Extension Study: Listeria Right Now™ Test for Detection of Listeria spp. from Selected Environmental Surfaces Without Enrichment: AOAC Performance Tested MethodSM 081802.

BACKGROUND: Listeria Right Now™ is a novel, enrichment-free test for the detection of Listeria spp. in swab samples taken from environmental surfaces. Results are available in less than 1 h. In a previous Performance Tested MethodSM (PTM) study, the test was validated for swab samples from stainless-steel and sealed concrete surfaces. OBJECTIVE: A PTM matrix extension study was conducted to validate the method for the detection of Listeria spp. in swab samples from ceramic tile, plastic, and rubber surfaces. METHODS: Performance of the Listeria Right Now method was compared to that of the U.S. Food and Drug Administration Bacteriological Analytical Manual reference culture procedure for the detection of Listeria spp. in swab samples taken from inoculated ceramic tile, plastic, and rubber surfaces. Data were analyzed using a probability of detection model. RESULTS: There were no significant differences in performance between the Listeria Right Now and reference culture methods for any of the three surfaces tested, as determined by probability of detection analysis. CONCLUSIONS: The Listeria Right Now method is an effective procedure for the detection of Listeria spp. from a variety of environmental surfaces. HIGHLIGHTS: Listeria Right Now provides accurate results, without enrichment, in real time. This enables food industry personnel to react swiftly to suspected Listeria contamination incidents.

The Validation of the RIDA®QUICK Gliadin for AOAC Research Institute.

RIDA®QUICK Gliadin is an immuno-chromatographic test for the detection of gluten in foods, on surfaces, and in Cleaning-in-Place (CIP) waters. This test kit has been adopted as Final Action AOAC INTERNATIONAL Official Methods of AnalysisSM 2015.16 for gluten in corn products. The assay is based on the monoclonal antibody R5, which recognizes gluten in wheat, barley, and rye. Four different surfaces were contaminated with a gliadin material and analyzed by a direct swabbing of the surface with the dip-stick. The outcome was an LOD95% concentration of the assay between 1.6 and 3.0 µg/100 cm2 gluten. For CIP waters that contain cleansing reagents, 100% positive results were obtained for minimum gluten concentration between 50 and 100 ng/mL. If the CIP water does not contain these reagents, the minimum detectable gluten level is 10 ng/mL. The independent validation study consisted of a method comparison study of recovery from a CIP solution and from a stainless-steel surface. The test kit was evaluated at six different concentration levels for both matrices, with 20 or 30 replicates per concentration level. The probability of detection was calculated for each contamination level. Additionally, the LOD95% concentration was estimated for each matrix analyzed.

The Validation of the Sample6 DETECTTM HT/L for AOAC Research Institute.

BACKGROUND: Listeria spp. are an important foodborne human pathogen because of their ability to cause disease and high mortality in individuals, particularly pregnant women, neonates, the elderly, immunocompromised individuals, and children. The Sample6 DETECTTM HT/L Kit is a semi-automated qualitative pathogen detection system designed to detect Listeria spp. (L. monocytogenes, L. innocua, L. ivanovii, L. seeligeri, L. welshimeri, and L. marthii) in environmental samples using the Sample6 BioIlluminationTM technology. OBJECTIVE: The study was done to evaluate the Sample6 DETECT HT/L Kit. The assay was evaluated for inclusivity, exclusivity, robustness, product consistency, and stability, and a matrix study of one environmental surface. METHODS: The performance of the Sample6 DETECT HT/L was compared with U.S. Food and Drug Administration reference culture method for Listeria using an unpaired study design. RESULTS: The Sample6 DETECT HT/L assay correctly identified all 50 inclusivity isolates and correctly excluded all 30 nontarget strains evaluated. The assay was not affected by minor variations in incubation temperature and time, or sample volume. Results across three production lots spanning the shelf life of the assay were consistent. In the matrix study, the Sample6 DETECT HT/L for Listeria correctly identified each test portion for the presence or absence of Listeria, and there were no statistically significant differences between candidate and reference method results. CONCLUSIONS: The data collected in this study demonstrate that the Sample6 DETECT HT/L assay is a reliable method for the detection of Listeria spp. on stainless-steel environmental surfaces after 22 h of enrichment.