Food And Drug Administration Bacteriological Analytical Manual Research Articles

Modeling Preharvest Cyclospora cayetanensis Sampling and Testing for Various Water and Produce Sampling Plans

As of August 2023, the two U.S. Food and Drug Administration (FDA) official detection methods for C. cayetanensis are outlined in the FDA Bacteriological Analytical Manual (BAM) Chapters 19b (produce testing) and 19c (agricultural water testing). These newly developed detection methods have been shown to not always detect contamination when present at low levels. Yet, industry and regulators may choose to use these methods as part of their monitoring and verification activities while detection methods continue to be improved. This study uses simulation to better understand the performance of these methods for various produce and water sampling plans. To do so, we used published FDA test validation data to fit a logistic regression model that predicts the methods’ detection rate given the number of oocysts present in a 10-L agricultural water or 25 g produce sample. By doing so, we were able to determine contamination thresholds at which different numbers of samples (n = 1, 2, 4, 8, 16, and 32) would be adequate for detecting contamination. Furthermore, to evaluate sampling plans in use cases, a simulation was developed to represent C. cayetanensis contamination in agricultural water and on cilantro throughout a 45-day growth cycle. The model included uncertainty around the contamination sources, including scenarios of unintentionally contaminated irrigation water or in-field contamination. The results demonstrate that in cases where irrigation water was the contamination source, frequent water testing proved to be more powerful than produce testing. In scenarios where contamination occurred in-field, conducting frequent produce testing or testing produce toward the end of the season more reliably detected contamination. This study models the power of C. cayetanensis detection methods to understand the sampling plan performance and how these methods can be better used to monitor this emerging food safety hazard.

Evaluation of the Thermo Scientific SureTectTM Listeria Species PCR Assay in a Broad Range of Foods and Selected Environmental Surfaces: Pre-Collaborative and Collaborative Study, First Action 2021.06.

BackgroundThe Thermo Scientific SureTect™ Listeria species PCR assay utilizes SolarisTM reagents for performing PCR for the rapid and specific detection of Listeria species in a broad range of foods and selected environmental surfaces.ObjectiveTo demonstrate reproducibility of the Thermo Scientific SureTect Listeria species PCR assay in a collaborative study using a challenging matrix, full-fat cottage cheese (25 g), to extend the scope of the method.MethodsIn the collaborative study, the candidate method was compared to the US Food and Drug Administration/Bacteriological Analytical Manual (FDA/BAM) Ch. 10 Listeria reference method. The candidate method used two PCR thermocyclers, the Applied Biosystems QuantStudio™ 5 Real-Time PCR instrument (QS5) and the Applied Biosystems 7500 Fast Real-Time PCR instrument (7500 Fast). The candidate method included its own confirmation procedure. Eighteen participants from 10 laboratories located within the United States and Europe were solicited for the collaborative study, with 12 participants submitting valid data. Statistical analysis was conducted according to the probability of detection (POD) statistical model. In addition, in order to extend the scope of the method, seven matrix studies were performed comparing the candidate method to the FDA/BAM reference method. One of these matrixes was also compared to the ISO 11290–1:2017 Microbiology of the food chain—Horizontal method for the detection and enumeration of Listeria monocytogenes and of Listeria spp.—Part 1: Detection method reference method.ResultsIn the collaborative study, the difference in laboratory results indicates equivalence between the candidate method and reference method for the matrix evaluated and the method demonstrated acceptable inter-laboratory reproducibility as determined in the collaborative evaluation. The two PCR instruments used in the study performed equivalently. All presumptive positives were confirmed via the alternative confirmation procedure. In the pre-collaborative studies, the results showed comparable performances between the candidate method and the reference method for all matrixes tested.ConclusionBased on the data generated, the method demonstrated acceptable inter-laboratory reproducibility data and statistical analysis.HighlightsDue to the COVID-19 pandemic, some participants had to be trained remotely. Additionally, 25 g full-fat cottage cheese is known to be a challenging matrix to test. No unusual cross-contamination, or false-positive/negative data was reported, highlighting the ease of use, reproducibility, and robustness of the candidate method.

Validation Study for PathogenDx EnviroX-F Assay for the Detection of Listeria, L. monocytogenes, and Salmonella in Environmental Surface Samples: AOAC Performance Tested MethodSM 092001.

The PathogenDx EnviroX-F uses microarray technology to simultaneously detect Listeria species, Listeria monocytogenes, and Salmonella species from environmental samples without the need for enrichment. The validation study included a matrix study of four matrices (stainless steel, plastic, rubber, and sealed concrete) comparing the PathogenDx EnviroX-F assay to the US Food and Drug Administration (FDA) Bacteriological Analytical Manual (BAM) Chapter 10, "Detection of L. monocytogenes in Foods and Environmental Samples, and Enumeration of L. monocytogenes in Foods" (revised March 2017), and FDA BAM Chapter 5,"Salmonella" (revised February 2020). Other required Performance Tested MethodSM parameters evaluated included: inclusivity and exclusivity, robustness, instrument variation, and product consistency and stability. The PathogenDx EnviroX-F assay was evaluated with 30 unpaired replicate surface areas for each environmental surface. The candidate method was evaluated without an enrichment step. In the inclusivity and exclusivity study 50 out of 50 Listeria isolates were detected, 50 out of 50 L. monocytogenes strains were detected, 108 out of 108 Salmonella strains were detected, and 95 out of 95 exclusivity strains were correctly excluded. In the matrix study, the PathogenDx EnviroX-F assay showed no significant differences between confirmed results or between candidate and reference method results for 4" × 4" environmental surface areas for each matrix. The PathogenDx EnviroX-F assay is an effective method for the qualitative detection of Listeria spp., L. monocytogenes, and Salmonella spp. from environmental surface swabs. The PathogenDx EnviroX-F assay will be the first PTM-approved multiplex assay for Listeria spp., L. monocytogenes, and Salmonella without the need for an environment step.

Evaluation of the Thermo ScientificTM SureTectTMListeria monocytogenes PCR Assay in a Broad Range of Foods and Selected Environmental Surfaces: Pre-Collaborative and Collaborative Study, First Action 2021.05.

BackgroundThe Thermo Scientific™ SureTect™ Listeria monocytogenes PCR Assay uses Solaris reagents for performing PCR for the rapid and specific detection of Listeria monocytogenes in a broad range of foods and selected environmental surfaces.ObjectiveTo demonstrate reproducibility of the SureTect Listeria monocytogenes PCR Assay in a collaborative study using a challenging matrix, full-fat cottage cheese (25 g). To extend the scope of the method.MethodIn the collaborative study, the candidate method was compared to the United States Food and Drug Administration/Bacteriological Analytical Manual (FDA/BAM) Chapter 10 Listeria reference method. The candidate method used two PCR thermocyclers, the Applied Biosystems™ QuantStudio™ 5 Real-Time PCR instrument (QS5) and the Applied Biosystems 7500 Fast Real-Time PCR instrument (7500 Fast). Eighteen participants from 10 laboratories located within the United States and Europe were solicited for the collaborative study, with 12 participants submitting valid data. Three levels of contamination were evaluated for each matrix. Statistical analysis was conducted according to the probability of detection (POD) statistical model. In addition, to extend the scope, six matrix studies were performed comparing the candidate method to the FDA/BAM reference method. One of these matrixes was also compared to the ISO 11290–1:2017 Microbiology of the Food Chain—Horizontal Method for the Detection and Enumeration of Listeria monocytogenes and of Listeria spp.—Part 1: Detection Method Reference Method.ResultsIn the collaborative study, the difference in laboratory results indicates equivalence between the candidate method and reference method for the matrix evaluated, and the method demonstrated acceptable inter-laboratory reproducibility as determined in the collaborative evaluation. The two PCR instruments used in the study performed equivalently. All presumptive positives were confirmed via the alternative confirmation procedure. In the pre-collaborative studies, the results showed comparable performances between the candidate method and the reference method for all matrixes tested.ConclusionsBased on the data generated, the method demonstrated acceptable inter-laboratory reproducibility data and statistical analysis.HighlightsDue to the COVID-19 pandemic, some participants had to be trained remotely. Additionally, 25 g full-fat cottage cheese is known to be a challenging matrix to test. No unusual cross-contamination or false positive/negative data were reported, highlighting the ease of use, reproducibility, and robustness of the method.

Comparison of Commercial Test Kits for Detection of Salmonella and E. coli O157:H7 in Alfalfa Spent Sprout Irrigation Water.

Sprout growers in the United States are required to test spent sprout irrigation water (SSIW) or in-process sprouts for Escherichia coli O157:H7 and Salmonella species. Pathogen screening kits are commercially available; however, few have been validated for analysis of sprouts or SSIW. This study evaluated AOAC-certified test kits (lateral flow devices [LFDs], enzyme immunoassays [EIAs], and molecular assays) in comparison with culture methods described in the U.S. Food and Drug Administration (FDA) Bacteriological Analytical Manual (BAM) for detection of Salmonella and E. coli O157:H7 in alfalfa SSIW. Twenty-five milliliter aliquots of alfalfa SSIW, either uninoculated or inoculated with Salmonella or E. coli O157:H7 at a low (∼0.5-0.7 CFU/25 mL) or high level (∼10-20 CFU/25 mL), were subjected to the enrichment and assay protocols recommended by each test. Pathogen presence was confirmed following FDA BAM procedures and, if applicable, test kit manufacturer protocols. Twelve of the 13 Salmonella test kits evaluated (except VIDAS UP) performed well and detected Salmonella in 100% of SSIW samples contaminated at 0.61 CFU/mL. Performance varied among E. coli O157:H7 test kits, with four (Reveal, MicroSEQ, GDS, MDA) of 12 kits designed for next-day detection, and four (Reveal, VIP Gold, MicroSEQ, GDS) of seven kits designed for same-day detection capable of detecting the pathogen in 100% samples contaminated at 0.90 CFU/mL. Enrichment conditions play a key role in determining the performance of test kits and the success of confirmation. This study is the first to compare a wide range of commercial test kits for detection of Salmonella and E. coli O157:H7 in SSIW.

Validation of the 3M™ Environmental Scrub Sampler with Wide-Spectrum Neutralizer: AOAC Performance Tested MethodSM 022104.

BackgroundThe 3M™ Environmental Scrub Sampler with 10 mL Wide Spectrum Neutralizer is a nonspecific sampling device intended for use for environmental monitoring surface sampling.ObjectiveThe aim was to evaluate 3M Wide Spectrum Neutralizer using the 3M Environmental Scrub Sampler for AOAC® Performance Tested MethodsSM (PTM) certification.MethodsMatrix studies, inclusivity/exclusivity, product consistency/stability, neutralization, and robustness testing were conducted for Salmonella and Listeria species. Stainless steel, sealed concrete, and plastic environmental surfaces were evaluated in the matrix study comparing the performance of the 3M™ method for sample collection to that of the U.S. Food and Drug Administration (FDA) Bacteriological Analytical Manual (BAM) reference methods. Four classes of sanitizers, namely quaternary ammonium, high acid, hydrogen/peroxyacetic acid and chlorine/bleach-based, were assessed in the neutralization study following ASTM E1054 - 08, Standard Test Methods for Evaluation of Inactivators of Antimicrobial Agents. The other testing parameters followed typical PTM study design.ResultsIn matrix studies the 3M sampling device demonstrated no significant differences between candidate and reference sampling method results. All inclusivity organisms were detected, and all exclusivity organisms were excluded, for both Salmonella and Listeria strains when tested by the appropriate FDA BAM detection method. Robustness, product consistency, and stability studies showed that the sampling device is not affected by lot or testing parameter differences. The Wide Spectrum Neutralizer was proven to effectively neutralize sanitizers at the concentrations tested and was itself shown to be nontoxic and did not affect target microorganism recovery.ConclusionsThe 3M Environmental Scrub Sampler with 10 mL Wide Spectrum Neutralizer is an effective, stable, robust sampling device for the recovery of Salmonella spp. and Listeria spp.HighlightThe 3M Environmental Scrub Sampler with 10 mL Wide Spectrum Neutralizer is an acceptable sampling device for use in FDA BAM Salmonella and Listeria reference methods.

Validation of PhageDx™ Cronobacter Assay for the Identification of Cronobacter Spp. in Powdered Infant Formula: AOAC Performance Tested MethodSM 051803.

BackgroundThe PhageDx™Cronobacter Assay is based on the infection of Cronobacter spp. by specific bacteriophages and expression of a luciferase reporter gene. Results are generated in as little as 18.5 h for powdered infant formula (PIF).ObjectiveAn AOAC Performance Tested MethodsSM (PTM) study was conducted to validate the PhageDx Cronobacter Assay for the detection of Cronobacter in 10, 100, and 300 g milk- and soy-based PIF test portions.MethodThe performance of the PhageDx method was compared to the ISO 22964:2006/2017 Microbiology of the Food Chain—Horizontal Method for the Detection of Cronobacter spp. and the U.S. Food and Drug Administration (FDA) Bacteriological Analytical Manual (BAM) Chapter 29 Cronobacter: 2012. Inclusivity/exclusivity, product consistency and stability, and robustness testing also were conducted.ResultsThere was no significant difference between the 10, 100, or 300 g test portions for the milk and soy PIF matrixes between the PhageDx Cronobacter Assay, the ISO 22964:2006/2017, and the FDA BAM Chapter 29 Cronobacter: 2012 methods. The reporter bacteriophages were specific for Cronobacter and infected 75 strains in inclusivity testing. They did not infect 35 non-Cronobacter bacteria in exclusivity testing. Robustness testing showed that the method performed well with specific deviations from the standard protocol. Consistency and stability testing demonstrated that the recombinant phage gave consistent results across three production lots and was stable when stored under appropriate conditions for at least 3 months.ConclusionsWork in the submitting and independent laboratories demonstrated that the PhageDx Cronobacter Assay meets the qualifications for PTM status.HighlightsThe PhageDx Cronobacter Assay is a rapid, simple, and specific test that has shown equivalence to both the FDA BAM and ISO reference methods for detecting Cronobacter spp. in PIF.

Rapid Screening for Salmonella in Raw Pet Food by Loop-Mediated Isothermal Amplification

Raw pet food, composed of raw meat and vegetables, has increased in popularity in recent years. Multiple surveys and frequent recalls indicate that this commodity has a high risk of contamination with Salmonella and other foodborne pathogens. Improved screening methods are needed to meet the growing demand for testing. This matrix verification study aimed to apply a Salmonella loop-mediated isothermal amplification (LAMP) method, recently completed multilaboratory validation in dry dog food, in several raw pet food matrices, following the U.S. Food and Drug Administration (FDA)'s method validation guidelines. Five types of raw pet food, consisting of freeze-dried beef and chicken treats and frozen beef, pork, and turkey complete foods, were evaluated. For each matrix, two sets of ten 25-g test portions (seven inoculated with ≤30 cells of Salmonella Typhimurium and three uninoculated controls) were examined. One set was preenriched in buffered peptone water and the other one was preenriched in lactose broth, which was followed by LAMP screening using two isothermal master mixes (ISO-001 and ISO-004). All results were confirmed by culture as specified in the FDA Bacteriological Analytical Manual (BAM). The LAMP method accurately detected Salmonella in all inoculated test portions of the five raw pet food samples, regardless of the preenrichment broth used. Positive results could be obtained within 4 min of the LAMP run using the ISO-004 master mix. All uninoculated controls tested negative using LAMP or BAM. In addition, one turkey-based complete pet food sample was found to be already contaminated with three Salmonella serovars harboring multiple antimicrobial resistance genes. The Salmonella LAMP method offers a rapid, reliable, and robust tool for routine screening of Salmonella in raw pet food, which will help better ensure product safety and protect public health.

Evaluation of the Solus One Salmonella Assay in Select Foods: Collaborative Study: First Action 2020.03.

The Solus One Salmonella immunoassay utilizes Salmonella specific selective media and automated liquid handling, for the rapid and specific detection of Salmonella species in select food types. The candidate method was evaluated using 375 g test portions in an unpaired study design for a single matrix, instant non-fat dry milk (NFDM) powder. The matrix was compared to the United States Food and Drug Administration/Bacteriological Analytical Manual (FDA/BAM) Chapter 5 Salmonella reference method. Eleven participants from 10 laboratories within academia and industry, located within the United States, Mexico, South Africa, Germany, and the United Kingdom, contributed data for the collaborative study. Three levels of contamination were evaluated for each matrix: an uninoculated control level [0 colony forming units (CFU)/test portion], a low inoculum level (0.2-2 CFU/test portion) and a high inoculum level (2-5 CFU/test portion). Statistical analysis was conducted according to the Probability of Detection (POD) statistical model. Results obtained for the low inoculum level test portions produced a dLPOD value with a 95% confidence interval between the candidate method confirmed (both alternative and conventional confirmation procedures) and the reference method of 0.07 (-0.02, 0.15). The dLPOD results indicate equivalence between the candidate method and the reference method for the matrix evaluated and the method demonstrated acceptable inter-laboratory reproducibility as determined in the collaborative evaluation. False positive and false negative rates were determined for the matrix and produce values of <2%. Based on the data generated, the method demonstrated acceptable inter-laboratory reproducibility data and statistical analysis.

Evaluation of the MC-Media PadTM Yeast and Mold Device for the Enumeration of Yeast and Mold: Collaborative Study, First Action 2018.02.

Background: The MC-Media Pad™ Yeast and Mold (YM) is a ready-to use culture device that combines a test pad coated with medium and water-absorption polymers that is designed for the rapid quantification of yeast and mold in food products. Objective: The MC-Media Pad YM was compared with the U.S. Food and Drug Administration (FDA) Bacteriological Analytical Manual (BAM) for the enumeration of yeast and mold in frozen orange juice concentrate. Methods: The candidate method was evaluated using a paired study design in a multilaboratory collaborative study following the current AOAC Validation Guidelines. Three target contamination levels (low, 10-100 CFU/g; medium, 100-1000 CFU/g; and high 1000-10 000 CFU/g) and an uninoculated control level (0 CFU/g) were evaluated. MC-Media Pad YM devices were enumerated after 48 and 72 h of incubation. Results: Plate count obtained by both methods were log-transformed and the difference of means (including 95% confidence intervals), repeatability SD, and SD were determined for each contamination level. Conclusions: No statistical difference was observed between the MC-Media Pad YM (for both 48 and 72 h) and the FDA BAM for each contamination level. Highlights: The new method offers a convenient alternative to the reference method (FDA BAM) for detection of yeast and mold contamination in food products, yielding reliable and comparable results in 48 h compared to 5 days for the reference method.

Application of an Environmental Phage-Based Assay (Sample6 Detect HT/L) for the Detection of Listeria spp. in Ice Cream.

Background: Dairy products are common sources of Listeria outbreaks, and early detection of the pathogen is critical to prevent outbreaks of illnesses and financial losses for dairy producers. Objective: This study aimed to evaluate Sample6 Detect HT/L for effective detection of Listeria monocytogenes and L. innocua in ice cream. Methods: Performance of the Sample6 DETECT HT/L was compared with U.S. Food and Drug Administration (FDA) Bacteriological Analytical Manual (BAM) Chapter 10 method for detection of Listeria spp. in ice cream using an unpaired study design. Results: R2-enriched samples tested with Sample6 Detect HT/L performed as well as the reference method at all time points tested from 15 to 24 h. R2 is a proprietary blend for use with the test kit that helps with early detection. All the dPODC values (Sample6 Detect HT/L presumptive and confirmed results) equaled zero, indicating 100% concordance between the methods. Both Sample6 Detect HT/L and FDA BAM results showed low dPODC values, with confidence intervals indicating no significant differences between Sample6 Detect HT/L and reference method results. Conclusions: Sample6 Detect HT/L is suitable to detect Listeria spp. in ice cream, even with a 12 h enrichment. Sample6 Detect HT/L demonstrated equivalent detection of L. monocytogenes and L. innocua from R2-enriched samples as expected with 15 and 18 h enrichment when compared with the 24 h FDA BAM method for L. monocytogenes. Highlights: These results indicate that Sample6 Detect HT/L, primarily developed for environmental samples, can be used to detect Listeria spp. in ice cream with less incubation time, resulting in faster detection.

Evaluation of Roka Atlas Salmonella method for the detection of Salmonella in egg products in comparison with culture method, real-time PCR and isothermal amplification assays

With the increasing focus on the food safety, rapid methods for the detection of Salmonella are crucial for both food industry and regulatory agencies. Recently, many molecular methodologies with diverse technologies have been introduced. Roka Atlas®Salmonella Assay (SEN) is a molecular method that uses ribosomal RNA as target for detection, which is theoretically more sensitive than PCR or isothermal amplification methods that target the DNA sequences of single genes. In this study, SEN assay was compared with four PCR- and isothermal amplification-based assays and a culture method, such as the MicroSEQ®Salmonella spp. Detection kit (MicroSEQ), 3M™ Molecular Detection Assay (MDA) Salmonella, ANSRTMSalmonella Assay (ANSR), and Pro-AmpRTTM SALM spp. Kit (Pro-AmpRT). Food samples were prepared and analyzed according to the current U. S. Food and Drug Administration (FDA) Bacteriological Analytical Manual (BAM) Salmonella culture method. A total of 155 bacterial isolates (121 for Salmonella inclusivity and 34 for Salmeonlla exclusivity) and 200 egg product samples inoculated at a level of 1–5 CFU/25 g were analyzed. The study also estimated the limit of detection of these molecular methods, and illustrated their advantages and disadvantages. For exclusivity, all 34 non-Salmonella isolates were negative by all 5 molecular methods studied. For inclusivity, all 121 Salmonella isolates were positive by MDA, ANSR, and Pro-AmpRT methods. However, the SEN and MicroSEQ results were negative for 9 samples inoculated with Salmonella bongori. The detection limit of the 5 molecular methods ranged from 1.76 to 3.76 log CFU/mL pre-enrichment culture, with the SEN assay being the most sensitive (1.76 – 2.64 log CFU/mL). The results indicated that the SEN assay was as effective and sensitive in detecting Salmonella enterica in egg products as was the FDA BAM culture method and the 4 other isothermal amplification and PCR methods evaluated in the study.

Optimized Culture Conditions for the Detection of Selected Strains of Bacillus in Eye Creams

Although eye area cosmetics contain preservatives, contamination can still occur during or after manufacture or through use. Understanding the likelihood of bacterial survival in eye creams begins with sensitive and accurate methods for the detection of bacterial contamination; therefore, we investigated optimal culture conditions, including neutralizers, dilution broths, and selective media for the detection of Bacillus in eye cream. Samples of three different brands of eye creams were first mixed with Tween 80, Tween 20, or a blend of Tween 60 and Span 80, then neutralized and non-neutralized samples were individually inoculated with B. cereus strains, B. mycoides, a mislabeled B. megaterium, B. subtilis or B. thuringiensis at a final concentration of 5 log CFU/g. The inoculated samples, with and without neutralizers, were spiral-plated and incubated at 30 °C for 24 h to 48 h. Presumptive colonies of Bacillus were enumerated on U. S. Food and Drug Administration Bacteriological Analytical Manual (FDA-BAM) referenced agars Bacillus cereus rapid agar (BACARA) and mannitol-egg yolk-polymixin agar (MYP). Our results show significant differences among the neutralizers, plates, and products. The combination of Tryptone- Azolectin-Tween and Tween 80 (TAT and T80) produced higher levels of Bacillus, estimated at 4.18 log CFU/g compared to growth on Modified letheen broth and Tween 80, which produced 3.97 log CFU/g (P &lt; 0.05). Colony counts of B. cereus cells on MYP agar were significantly higher, than those on BACARA agar, showing an average of 4.25 log CFU/g versus 3.84 log CFU/g, respectively (P &lt; 0.05). The growth of the strain mislabeled B. megaterium ATCC 6458 on B. cereus selective agars BACARA and MYP agar led us to further investigations. We identified bi-pyramidal crystals among colonies of the strain, and subsequent PCR identified the cry 1 gene, indicating that strain was actually B. thuringiensis subps. kurstaki.

Prevalence and Antibiotic Susceptibility of Salmonella species Isolated from Beef and its Related Samples in Techiman Municipality of Ghana

Salmonella species are important foodborne pathogens that have been implicated in a number of foodborne outbreaks. A total of 240 beef and its related samples obtained from the Techiman Municipality of Ghana were screened using the conventional method in the Food and Drug Administration-Bacteriological Analytical Manual (FDA-BAM)-USA. The overall prevalence of Salmonella species was 57.08%. The prevalence of Salmonella species ranged from 33.30% to 75.00% in the meat and its related samples (table, knife and apron), and 6.30% to 93.80% at the various meat sale points (locations where meat is sold). Prevalence of Salmonella species was significantly higher in meat (75.00%), table (60.00%) and knife (60.00%), than apron (33.33%). The most contaminated meat sale point was Kenten and Main markets (93.75%) and the least contaminated sale point was Sansema junction (6.25%). All the Salmonella species were susceptible to ciprofloxacin but resistant to vancomycin. Intermediate resistances occur for all the antibiotics except ciprofloxacin and vancomycin. The Salmonella species also exhibited 23 antibiotic resistant patterns with the pattern EVa (erythromycin and vancomycin) being the commonest (exhibited by nine different isolates). Multiple antibiotic index (MAR index) ranged from 0.11 to 0.67. This study revealed that beef and its related samples in Techiman markets are contaminated with Salmonella.

Evaluation of the 3M™ Petrifilm™ Salmonella express system for the detection of Salmonella species in selected foods: collaborative study.

The 3M™ Petriflm™ Salmonella Express (SALX) System is a simple, ready-to-use chromogenic culture medium system for the rapid qualitative detection and biochemical confirmation of Salmonella spp. in food and food process environmental samples. The 3M Petrifilm SALX System was compared using an unpaired study design in a multilaboratory collaborative study to the U.S. Department of Agriculture/Food Safety and Inspection Service (USDA/FSIS) Microbiology Laboratory Guidebook (MLG) 4.07 (2013) Isolation and Identification of Salmonella from Meat, Poultry, Pasteurized Egg and Catfish Products and Carcass and Environmental Sponges for raw ground beef and the U.S. Food and Drug Administration Bacteriological Analytical Manual (FDA/BAM) Chapter 5, Salmonella (2011) reference method for dry dog food following the current AOAC validation guidelines. For this study, a total of 17 laboratories located throughout the continental United States evaluated 1872 test portions. For the 3M Petrifilm SALX System, raw ground beef was analyzed using 25 g test portions, and dry dog food was analyzed using 375 g test portions. For the reference methods, 25 g test portions of each inatrix were analyzed. The two matrices were artificially contaminated with Salmonella at three inoculation levels: an uninoculated control level (0 CFU/test portion), a low inoculum level (0.2-2 CFU/test portion), and a high inoculum level (2-5 CFU/test portion). Each inoculation level was statistically analyzed using the probability of detection statistical model. For the raw ground beef and dry dog food test portions, no significant differences at the 95% confidence interval were observed in the number of positive samples detected by the 3M Petrifilm SALX System versus either the USDA/FSIS-MLG or FDA/BAM methods.

Crystal Diagnostics MultiPath System™.

The Crystal Diagnostics MultiPath System™ provides rapid detection of Escherichia coli O157 in fresh raw ground beef, raw beeftrim, and spinach. The Crystal Diagnostics system combines patented Liquid Crystal technology with antibody-coated paramagnetic microspheres to selectively capture and detect E. coli O157 in food matrixes. This is the only liquid crystal-based biosensor commercially available for the detection of pathogens. The Crystal Diagnostics system expeditiously provides the sensitivity and accuracy of the U.S. Department of Agriculture Food Safety Inspection Service (USDA-FSIS) and the U.S. Food and Drug Administration Bacteriological Analytical Manual (FDA-BAM) methods for detecting as low as one CFU of E. coli O157 per 375 g of raw ground beef and raw beef trim, or 200 g of raw spinach. An internal inclusivity validation demonstrated detection of all 50 tested strains of . coli O157. The internal and independent laboratory tests demonstrate that the method is rapid and sensitive for detecting of E. coli O157 in fresh raw ground beef, beef trim, and spinach.

Evaluation of 3M™ Molecular Detection Assay (MDA) Salmonella for the Detection of Salmonella in Selected Foods: Collaborative Study

The 3M Molecular Detection Assay (MDA) Salmonella is used with the 3M Molecular Detection System for the detection of Salmonella spp. in food, food-related, and environmental samples after enrichment. The assay utilizes loop-mediated isothermal amplification to rapidly amplify Salmonella target DNA with high specificity and sensitivity, combined with bioluminescence to detect the amplification. The 3M MDA Salmonella method was compared using an unpaired study design in a multilaboratory collaborative study to the U.S. Department of Agriculture/Food Safety and Inspection Service-Microbiology Laboratory Guidebook (USDA/FSIS-MLG 4.05), Isolation and Identification of Salmonella from Meat, Poultry, Pasteurized Egg and Catfish Products for raw ground beef and the U.S. Food and Drug Administration/Bacteriological Analytical Manual (FDA/BAM) Chapter 5 Salmonella reference method for wet dog food following the current AOAC guidelines. A total of 20 laboratories participated. For the 3M MDA Salmonella method, raw ground beef was analyzed using 25 g test portions, and wet dog food was analyzed using 375 g test portions. For the reference methods, 25 g test portions of each matrix were analyzed. Each matrix was artificially contaminated with Salmonella at three inoculation levels: an uninoculated control level (0 CFU/test portion), a low inoculum level (0.2-2 CFU/test portion), and a high inoculum level (2-5 CFU/test portion). In this study, 1512 unpaired replicate samples were analyzed. Statistical analysis was conducted according to the probability of detection (POD). For the low-level raw ground beef test portions, the following dLPOD (difference between the POD of the reference and candidate method) values with 95% confidence intervals were obtained: -0.01 (-0.14, +0.12). For the low-level wet dog food test portions, the following dLPOD with 95% confidence intervals were obtained: -0.04 (-0.16, +0.09). No significant differences were observed in the number of positive samples detected by the 3M MDA Salmonella method versus either the USDA/FSIS-MLG or FDA/BAM methods.

Atlas™ Salmonella Detection Method Using Transcription Mediated Amplification (TMA) to Detect Salmonella enterica in a Variety of Foods and Select Surfaces

The Atlas Salmonella detection assay was compared to the reference culture methods for 12 foods and three surfaces. Comparison of the Atlas method to the U.S. Food and Drug Administration Bacteriological Analytical Manual (FDA/BAM) and U.S. Department of Agriculture-Food Safety and Inspection Service/Microbiology Laboratory Guidebook (USDA-FSIS/MLG) reference methods required an unpaired approach. Each method had a total of 320 samples inoculated with an S. enterica strain. Each food and surface was inoculated with a different strain of S. enterica at two different levels/ method. Meat and egg products were compared to the USDA-FSIS/MLG 4.05 method. All other foods were compared to the FDA/BAM-5 method. The Atlas method had 148 positives out of 320 total inoculated samples, compared to 119 positives for the reference methods. Overall, the probability of detection analysis of the results showed equivalent or better performance by the Atlas Salmonella detection method compared to the reference methods. The Atlas Salmonella detection assay detected all 100 inclusive organisms and none of the 30 exclusive organisms. The lot-to-lot and kit stability studies showed no statistical differences between lots or over the term of the shelf-life. Instrument-to-instrument testing showed no statistical difference between instruments. Finally, the robustness study showed no difference when the sample volume added to the Atlas Salmonella detection assay varied by 10%, storage time was extended up to 5 days before analysis, or enrichment times were varied from 12 to 24 h.

VIDAS® Listeria species Xpress (LSX)

The AOAC GovVal study compared the VIDAS Listeria species Xpress (LSX) to the Health Products and Food Branch MFHPB-30 reference method for detection of Listeria on stainless steel. The LSX method utilizes a novel and proprietary enrichment media, Listeria Xpress broth, enabling detection of Listeria species in environmental samples with the automated VIDAS in a minimum of 26 h. The LSX method also includes the use of the chromogenic media, chromID Ottaviani Agosti Agar (OAA) and chromID Lmono for confirmation of LSX presumptive results. In previous AOAC validation studies comparing VIDAS LSX to the U.S. Food and Drug Administration's Bacteriological Analytical Manual (FDA-BAM) and the U.S. Department of Agriculture-Food Safety and Inspection Service (USDA-FSIS) reference methods, the LSX method was approved as AOAC Official Method 2010.02 for the detection of Listeria species in dairy products, vegetables, seafood, raw meats and poultry, and processed meats and poultry, and as AOAC Performance Tested Method 100501 in a variety of foods and on environmental surfaces. The GovVal comparative study included 20 replicate test portions each at two contamination levels for stainless steel where fractionally positive results (5-15 positive results/20 replicate portions tested) were obtained by at least one method at one level. Five uncontaminated controls were included. In the stainless steel artificially contaminated surface study, there were 25 confirmed positives by the VIDAS LSX assay and 22 confirmed positives by the standard culture methods. Chi-square analysis indicated no statistical differences between the VIDAS LSX method and the MFHPB-30 standard methods at the 5% level of significance. Confirmation of presumptive LSX results with the chromogenic OAA and Lmono media was shown to be equivalent to the appropriate reference method agars. The data in this study demonstrate that the VIDAS LSX method is an acceptable alternative method to the MFHPB-30 standard culture method for the detection of Listeria species on stainless steel.

Samsung Salmonella Detection Kit

Salmonella, one of the most common causes of foodborne illness, is a significant public health concern worldwide. There is a need in the food industry for methods that are simple, rapid, and sensitive for the detection of foodborne pathogens. In this study, the Samsung Salmonella Detection Kit, a real-time PCR assay for the detection of Salmonella, was evaluated according to the current AOAC guidelines. The validation consisted of lot-to-lot consistency, stability, robustness, and inclusivity/exclusivity studies, as well as a method comparison of 10 different food matrixes. In the validation, the Samsung Salmonella Detection Kit was used in conjunction with the Applied Biosystems StepOnePlus PCR system and the Samsung Food Testing Software for the detection of Salmonella species. The performance of the assays was compared to the U.S. Department of Agriculture/Food Safety and Inspection Service-Microbiology Laboratory Guidebook (USDA/FSIS-MLG) 4.05: Isolation and Identification of Salmonella from Meat, Poultry, Pasteurized Egg, and Catfish and the and U.S. Food and Drug Administration/Bacteriological Analytical Manual (FDA/BAM) Chapter 5 Salmonella reference methods. The validation was conducted using an unpaired study design for detection of Salmonella spp. in raw ground beef, raw pork, raw ground pork, raw chicken wings, raw salmon, alfalfa sprouts, pasteurized orange juice, peanut butter, pasteurized whole milk, and shell eggs. The Samsung Salmonella Detection Kit demonstrated lot-to-lot consistency among three independent lots as well as ruggedness with minor modifications to changes in enrichment incubation time, enrichment incubation temperature, and DNA sample volume for PCR reaction. Stability was observed for 13 months at -20 degrees C and 3 months at 5 degrees C. For the inclusivity/exclusivity study, the Samsung Salmonella Detection Kit correctly identified 147 Salmonella species isolates out of 147 isolates tested from each of three different enrichment broths (a total of 441 isolates detected), and correctly excluded all 31 nontarget strains analyzed. For the method comparison, statistical analysis was conducted according to the Mantel-Haenszel Chi-square formula for unpaired test portions, and there was no significant difference in the number of positive samples detected between the Samsung Salmonella Detection Kit and the USDA/FSIS-MLG and FDA/BAM reference methods for all 10 food matrixes.