Inactivation of Escherichia coli, Salmonella enterica, and Listeria monocytogenes using the Contamination Sanitization Inspection and Disinfection (CSI-D) device.

The Contamination Sanitization Inspection and Disinfection (CSI-D) device is a handheld fluorescence-based imaging system designed to disinfect food contact surfaces using ultraviolet-C (UVC) illumination. This study aimed to determine the optimal CSI-D parameters (i.e., UVC exposure time and intensity) for the inactivation of the following foodborne bacteria plated on non-selective media: generic Escherichia coli (indicator organism) and the pathogens enterohemorrhagic E. coli, enterotoxigenic E. coli, Salmonella enterica, and Listeria monocytogenes. Each bacterial strain was spread-plated on non-selective agar and exposed to high-intensity (10 mW/cm2) or low-intensity (5 mW/cm2) UVC for 1-5 s. Control plates were not exposed to UVC. The plates were incubated overnight at 37 °C and then enumerated. Three trials for each bacterial strain were conducted. Statistical analysis was carried out to determine if there were significant differences in bacterial growth between UVC intensities and exposure times. Overall, exposure to low or high intensity for 3-5 s resulted in consistent inhibition of bacterial growth, with reductions of 99.9-100 % for E. coli, 96.8-100 % for S. enterica, and 99.2-100 % for L. monocytogenes. The 1 s exposure time showed inconsistent results, with a 66.0-100 % reduction in growth depending on the intensity and bacterial strain. When the results for all strains within each species were combined, the 3-5 s exposure times showed significantly greater (p < 0.05) growth inhibition than the 1 s exposure time. However, there were no significant differences (p > 0.05) in growth inhibition between the high and low UVC intensities. The results of this study show that, in pure culture conditions, exposure to UVC with the CSI-D device for ≥3 s is required to achieve consistent reduction of E. coli, S. enterica, and L. monocytogenes.

DNA barcoding of herbal supplements on the US commercial market associated with the purported treatment of COVID-19.

INTRODUCTION: The COVID-19 pandemic was associated with an increased global use of traditional medicines, including Ayurvedic herbal preparations. Due to their growing demand, their processed nature, and the complexity of the global supply chain, there is an increased risk of adulteration in these products. OBJECTIVES: The objective of this study was to assess the use of DNA barcoding for species identification in herbal supplements on the US market associated with the Ayurvedic treatment of respiratory symptoms. METHODS: A total of 54 commercial products containing Ayurvedic herbs were tested with four DNA barcoding regions (i.e., rbcL, matK, ITS2, and mini-ITS2) using two composite samples per product. Nine categories of herbs were targeted: amla, ashwagandha, cinnamon, ginger, guduchi, tribulus, tulsi, turmeric, and vacha. RESULTS: At least one species was identified in 64.8% of products and the expected species was detected in 38.9% of products. Undeclared plant species, including other Ayurvedic herbs, rice, and pepper, were detected in 19 products, and fungal species were identified in 12 products. The presence of undeclared plant species may be a result of intentional substitution or contamination during harvest or processing, while fungal DNA was likely associated with the plant material or the growing environment. The greatest sequencing success (42.6-46.3%) was obtained with the matK and rbcL primers. CONCLUSION: The results of this study indicate that a combination of genetic loci should be used for DNA barcoding of herbal supplements. Due to the limitations of DNA barcoding in identification of these products, future research should incorporate chemical characterization techniques.

A Novel Machine-Learning Framework Based on a Hierarchy of Dispute Models for the Identification of Fish Species Using Multi-Mode Spectroscopy.

Seafood mislabeling rates of approximately 20% have been reported globally. Traditional methods for fish species identification, such as DNA analysis and polymerase chain reaction (PCR), are expensive and time-consuming, and require skilled technicians and specialized equipment. The combination of spectroscopy and machine learning presents a promising approach to overcome these challenges. In our study, we took a comprehensive approach by considering a total of 43 different fish species and employing three modes of spectroscopy: fluorescence (Fluor), and reflectance in the visible near-infrared (VNIR) and short-wave near-infrared (SWIR). To achieve higher accuracies, we developed a novel machine-learning framework, where groups of similar fish types were identified and specialized classifiers were trained for each group. The incorporation of global (single artificial intelligence for all species) and dispute classification models created a hierarchical decision process, yielding higher performances. For Fluor, VNIR, and SWIR, accuracies increased from 80%, 75%, and 49% to 83%, 81%, and 58%, respectively. Furthermore, certain species witnessed remarkable performance enhancements of up to 40% in single-mode identification. The fusion of all three spectroscopic modes further boosted the performance of the best single mode, averaged over all species, by 9%. Fish species mislabeling not only poses health-related risks due to contaminants, toxins, and allergens that could be life-threatening, but also gives rise to economic and environmental hazards and loss of nutritional benefits. Our proposed method can detect fish fraud as a real-time alternative to DNA barcoding and other standard methods. The hierarchical system of dispute models proposed in this work is a novel machine-learning tool not limited to this application, and can improve accuracy in any classification problem which contains a large number of classes.

Microbiological safety and quality of ceviche, poke, and sushi dishes sold at retail outlets in Orange County, CA.

Raw, ready-to-eat (RTE) seafood products, such as ceviche, poke, and sushi, have experienced growing demand globally; however, these products have the potential to be contaminated with foodborne pathogens. The objective of this study was to determine the prevalence of Escherichiacoli/coliforms, Salmonella, and Listeria in ceviche, poke, and sushi dishes sold at the retail level in Orange County, CA, USA. Additional organisms detected during testing were also considered in the results. A total of 105 raw, RTE samples of ceviche, poke, and sushi were collected from restaurants and grocery stores in Orange County, CA. Samples were tested for Salmonella and Listeria utilizing methods from the Food and Drug Administration (FDA) Bacteriological Analytical Manual (BAM). E. coli and total coliforms were enumerated utilizing 3 M Petrifilm plates. Overall, two samples (1.9%) were positive for generic E. coli, with a range of 5-35 CFU/g. Coliforms were detected in 85 samples (81%), with a range of 5-1710 CFU/g. The average coliform levels in ceviche samples (259 CFU/g) were significantly higher than the levels in sushi samples (95 CFU/g), according to a Kruskal-Wallis H test followed by the Dunn test (p < 0.05). The coliform levels in poke samples (196 CFU/g) were not significantly different from those in ceviche or sushi. All levels of E. coli and coliforms were considered acceptable or satisfactory/borderline according to standards for RTE seafood. None of the samples tested positive for Salmonella or Listeria monocytogenes; however, other microorganisms were detected in 17 samples, including Listeria spp., Proteus mirabilis, Providencia rettgeri, and Morganella morganii. The results of this study are novel in that they present data on the microbiological safety and quality of ceviche, poke, and sushi dishes sold at retail in the United States, as well as provide a comparison across the three categories of raw, RTE seafood.

Rapid Assessment of Fish Freshness for Multiple Supply-Chain Nodes Using Multi-Mode Spectroscopy and Fusion-Based Artificial Intelligence.

This study is directed towards developing a fast, non-destructive, and easy-to-use handheld multimode spectroscopic system for fish quality assessment. We apply data fusion of visible near infra-red (VIS-NIR) and short wave infra-red (SWIR) reflectance and fluorescence (FL) spectroscopy data features to classify fish from fresh to spoiled condition. Farmed Atlantic and wild coho and chinook salmon and sablefish fillets were measured. Three hundred measurement points on each of four fillets were taken every two days over 14 days for a total of 8400 measurements for each spectral mode. Multiple machine learning techniques including principal component analysis, self-organized maps, linear and quadratic discriminant analyses, k-nearest neighbors, random forest, support vector machine, and linear regression, as well as ensemble and majority voting methods, were used to explore spectroscopy data measured on fillets and to train classification models to predict freshness. Our results show that multi-mode spectroscopy achieves 95% accuracy, improving the accuracies of the FL, VIS-NIR and SWIR single-mode spectroscopies by 26, 10 and 9%, respectively. We conclude that multi-mode spectroscopy and data fusion analysis has the potential to accurately assess freshness and predict shelf life for fish fillets and recommend this study be expanded to a larger number of species in the future.

Labeling compliance and online claims for Ayurvedic herbal supplements on the U.S. market associated with the purported treatment of COVID-19.

During the COVID-19 pandemic, many consumers increased their use of supplements that claimed to support immune health, including Ayurvedic preparations. The goal of this study was to analyze labeling compliance and online claims for Ayurvedic herbal supplements associated with the purported treatment of COVID-19. The physical product labels for 51 herbal supplements labeled as ginger, tulsi/holy basil, amla, vacha/calamus root, guduchi/giloy, cinnamon, ashwagandha, tribulus, or turmeric were assessed for U.S. regulatory compliance. Disease claims, structure/function claims, and general well-being claims were also examined. The online listings for products purchased online (n = 42) were examined for claims and for the presence of the required legal disclaimer. Collectively, 61% of products had at least one instance of noncompliance on the physical label. The most common violations included missing/noncompliant disclaimer (33%), noncompliant "Supplement Facts" label (29%), noncompliant statement of identity (27%) and noncompliant domestic mailing address or phone number (25%). Structure/function claims occurred more frequently in the online product listings (average of 5 claims per product) compared to the physical labels (average of 2 claims per product). Disease claims were observed for 38% of online product listings and on 8% of physical labels. The use of disease claims on herbal supplements is a significant concern for public health because it may lead consumers to delay seeking professional treatment for life-threatening diseases. Overall, this study revealed a lack of labeling compliance among Ayurvedic herbal supplements and a need for greater scrutiny and monitoring of online product listings.

Bovine Liver Supplement Labeling Practices and Compliance With U.S. Regulations.

Bovine liver supplements are sought after by consumers due to their nutrient-dense profile and high protein content. However, there is a lack of information regarding bovine liver supplement labeling practices. The objective of this study was to assess labeling practices and compliance with U.S. regulatory standards among commercially sold bovine liver supplements. The product labels for 49 bovine liver supplements were examined for required information, including a statement of identity; net quantity of contents; "Supplement Facts" label; ingredient statement; and name and place of business of manufacturer, packer, or distributor with domestic address or telephone number. Any claims made on the supplement labels were also reviewed for compliance. Overall, 59% of the products had at least one instance of noncompliance with U.S. labeling regulations. The main categories of noncompliance were missing a domestic mailing address or phone number (39% of products), noncompliant nutrient content claim (31% of products), and missing/noncompliant disclaimer for a nutritional support statement (6% of products). The lack of a mailing address or phone number is problematic because it prevents consumers from being able to report serious adverse events to the manufacturer. The majority (85%) of the nutrient content observed on product labels was found to be noncompliant. Noncompliant nutrient content claims are a major concern for consumers who rely on these claims to assess the nutritional benefits of a product. Overall, the results of this study revealed a lack of labeling compliance in bovine liver supplements, indicating a need for increased awareness and monitoring.

Use of Molecular Methods to Authenticate Animal Species and Tissue in Bovine Liver Dietary Supplements.

Dietary supplements containing bovine (subfamily Bovinae) liver are susceptible to fraud due to their high value and the lack of modern detection methods available for processed animal tissues. The objective of this research was to use molecular methods to authenticate dietary supplements claiming to contain bovine liver or beef liver through the verification of animal species and tissue type. A total of 53 bovine/beef liver dietary supplements were purchased from online sources. The presence of liver was verified with reverse transcription and real-time PCR testing for microRNA-122 (miR-122), which is highly expressed in liver tissue. Multiplex real-time PCR targeting domestic cattle (Bos taurus), horse (Equus caballus), sheep (Ovis aries), and pork (Sus scrofa) was used to verify species. Samples that failed species identification with multiplex real-time PCR underwent DNA mini-barcoding. Overall, bovine species were detected in 48/53 liver supplements: 35 samples were confirmed as domestic cattle with multiplex real-time PCR and an additional 13 samples were confirmed as domestic cattle or Bos spp. with DNA mini-barcoding. One of these samples was also positive for sheep/lamb, which was declared on the label. One product contained undeclared pork in addition to beef. MiR-122 was detected in 51 out of 53 supplements, suggesting the presence of liver. While this study demonstrates the potential use of tissue-specific microRNAs in verifying tissues in dietary supplements, more research is needed to evaluate the specificity of these markers.

An investigation into country of origin labeling, species authentication and short weighting of commercially sold frozen fish fillets.

Proper labeling of seafood is important to prevent economic deception and protect public health. The goal of this research was to investigate prepackaged frozen fish for Country of Origin Labeling (COOL) compliance, species labeling, net weights/short weighting, and percent glaze. A total of 111 frozen prepackaged fish fillets were purchased from grocery stores in Southern California (USA). Samples were designated as COOL compliant if they displayed both procurement method and country of origin in accordance with COOL requirements. Species labeling was examined by comparing the species identified with DNA barcoding to the acceptable market names provided in the FDA Seafood List. Net weights and percent glaze were determined by recording the weight of each product before and after deglazing. Of the 111 samples, only 1 was noncompliant with COOL and 10 samples (9%) were short-weighted. The average percent glaze was 5%, with seven samples having >10% glaze. Most fish (95.5%) were correctly labeled with regards to species. Species substitution was discovered in two samples and three samples had unacceptable market names. The results of this study indicate high COOL compliance and minimal species mislabeling in prepackaged frozen fish fillets. However, there is a need for increased focus on short weighting and/or overglazing of frozen fish products.

Application of whole-genome sequencing for norovirus outbreak tracking and surveillance efforts in Orange County, CA.

Noroviruses are the leading cause of acute gastroenteritis and foodborne illness in the United States. Traditional Sanger sequencing of short genomic regions (~300-600 bp) is the primary method for differentiation of this pathogen; however, whole-genome sequencing (WGS) offers a valuable approach to further characterize strains of this virus. The objective of this study was to investigate the ability of WGS compared to Sanger sequencing to differentiate norovirus strains and enhance outbreak investigation and surveillance efforts. WGS results for 41 norovirus-positive stool samples from 15 different outbreaks occurring from 2012 to 2019 in Orange County, CA, were analyzed for this study. All samples were genotyped with both WGS and Sanger sequencing based on the B-C region. WGS generated nearly full-length viral genome sequences (7029-7768 bp) with 4x to 35,378x coverage. Phylogenetic analysis of WGS data enabled differentiation of genotypically similar strains from separate outbreaks. Single nucleotide variation (SNV) analysis on a subset of strains revealed nucleotide variations (15-79 nt) among isolates from multiple outbreaks of GII.4 Sydney_2015[P31] and GII.17[P17]. Overall, the results demonstrated that coupling norovirus genotype identification with WGS enables enhanced genetic differentiation of strains and provides valuable information for outbreak investigation and surveillance efforts.

DNA-based techniques for seafood species authentication.

Global trade of seafood has increased in the last decade, leading to significant concerns associated with seafood fraud. Seafood fraud involves the intentional misrepresentation of fish or shellfish for the purpose of economic gain and includes acts such as species substitution, illegal transshipment, overtreatment/short weighting, and mislabeling country of origin or production method. These fraudulent acts have had economic, environmental, and public health consequences on a global level. DNA-based techniques for seafood authentication are utilized by regulatory agencies and can be employed as part of a food fraud risk mitigation plan. This chapter will focus specifically on the use of DNA-based methods for the detection of seafood species substitution. Various methods have been developed for DNA-based species identification of seafood, including polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), species-specific PCR, real-time PCR, Sanger sequencing, microarrays, and high-resolution melting (HRM). Emerging techniques for seafood authentication include droplet digital PCR, isothermal amplification, PCR-enzyme-linked immunosorbent assay (ELISA), and high-throughput or next-generation sequencing. Some of these DNA-based methods target specific species, such as real-time PCR and droplet digital PCR, while other methods allow for simultaneous differentiation of a wide range of fish species, including Sanger sequencing and high-throughput sequencing. This chapter will begin with an introduction on seafood fraud and species substitution, followed by an analysis of the main DNA-based authentication methods and emerging techniques for species identification.

Use of DNA Barcoding Combined with PCR-SFLP to Authenticate Species in Bison Meat Products.

American bison (Bison bison) meat is susceptible to species mislabeling due to its high value and similar appearance to meat from domestic cattle (Bos taurus). DNA barcoding is commonly used to identify animal species. However, as a result of the historical hybridization of American bison and domestic cattle, additional genetic testing is required for species confirmation. The objective of this study was to perform a market survey of bison meat products and verify the species using DNA barcoding combined with polymerase chain reaction-satellite fragment length polymorphism (PCR-SFLP). Bison products (n = 45) were purchased from a variety of retailers. Samples that were positive for domestic cattle with DNA barcoding were further analyzed with PCR-SFLP. DNA barcoding identified bison in 41 products, red deer (Cervus elaphus) in one product, and domestic cattle in three products. PCR-SFLP confirmed the identification of domestic cattle in two samples, while the third sample was identified as bison with ancestral cattle DNA. Overall, mislabeling was detected in 3 of the 45 samples (6.7%). This study revealed that additional DNA testing of species that have undergone historical hybridization provides improved identification results compared to DNA barcoding alone.

Shark Cartilage Supplement Labeling Practices and Compliance with U.S. Regulations.

The objective of this study was to analyze labeling practices and compliance with regulatory standards for shark cartilage supplements sold in the United States. The product labels of 29 commercial shark cartilage supplements were assessed for compliance with U.S. regulations. Claims, including nutrient content, prohibited disease, and nutritional support statements, were examined for compliance and substantiation. Overall, 48.3% of the samples had at least one instance of noncompliance with labeling regulations. The most common labeling violations observed were: missing a domestic address/phone number, non-compliant nutrient content claim, missing/incomplete disclaimer, missing statement of identity, prohibited disease claims, and incomplete "Supplement Facts" label. The use of prohibited disease claims and nutritional support statements without the required disclaimer is concerning from a public health standpoint because consumers may delay seeking professional treatment for a disease. The results of this study indicate a need for improved labeling compliance among shark cartilage supplements.

Microplate immunocapture coupled with the 3M molecular detection system and selective plating for the rapid detection of Salmonella infantis in dry dog food and treats.

The objective of this study was to use microplate immunocapture (IC) to reduce the enrichment time required for detection of Salmonella in pet food with the 3 M Molecular Detection System (MDS) or selective plating on XLD. Dog food and pig ear treats were inoculated with Salmonella Infantis at concentrations of 100-104 CFU/25 g, followed by a 3-h enrichment, then microplate IC and 3 M MDS or microplate IC and selective plating on XLD. Another set of samples underwent a traditional 24-h enrichment followed by 3 M MDS or selective plating. Based on the results of three independent trials, microplate IC followed by selective plating enabled detection of Salmonella in 100% of dog food and treat samples tested, including at levels as low as 100 CFU/25 g. Microplate IC coupled with 3 M MDS enabled detection of Salmonella in dog food and treat samples down to levels of 100 CFU/25 g, with an overall detection rate of 92%. These results indicate high potential for microplate IC to be used in place of the traditional 24-h enrichment step, enabling detection of Salmonella in complex matrices when coupled with 3 M MDS or selective plating.

Concentration of Listeria monocytogenes in skim milk and soft cheese through microplate immunocapture.

Microplate immunocapture is an inexpensive method for the concentration of foodborne pathogens using an antibody-coated microplate. The objective of this study was to determine the efficacy of microplate immunocapture as an alternative to traditional enrichment for concentrating Listeria monocytogenes to levels detectable with selective plating or real-time PCR. L. monocytogenes isolates serologically characterized as Type 1 (1/2a) and Type 4 (untypeable) were grown overnight and diluted to 100 to 106 colony-forming units (CFU)/mL. The isolates were used to optimize microplate immunocapture in tryptic soy broth with 0.6% yeast extract (TSBYE), skim milk, and queso fresco samples. Following microplate immunocapture, the bacteria were streaked onto polymyxin-acriflavine-LiCl-ceftazidime-aesculin-mannitol (PALCAM) agar, followed by incubation at 37 °C for 24 ±â€¯2 h. The bacteria also underwent real-time polymerase chain reaction (PCR). The optimized microplate immunocapture method was tested in triplicate for its ability to capture L. monocytogenes in broth and food samples. Overall recovery rates for L. monocytogenes in food samples at cell populations of 100, 102, and 104 CFU/25 g using microplate immunocapture with real-time PCR were 88.9%, 94.4%, and 100%, respectively. Recovery in these matrices using microplate immunocapture with selective plating was comparatively lower, at 0%, 44.4%, and 100%, respectively. Conventional culture method showed 100% detection at each inoculation level. Microplate immunocapture combined with real-time PCR shows high potential to reduce the time required for detection, with concentration of L. monocytogenes to detectable levels within 1-4 h. The incorporation of a short enrichment step may improve recovery rates at low cell levels.

Use of enzyme-linked immunosorbent assay to screen for aflatoxins, ochratoxin A, and deoxynivalenol in dry pet foods.

The objective of this study was to perform a market survey on dry pet foods using enzyme-linked immunosorbent assay (ELISA) to detect total aflatoxins (AFs), ochratoxin A (OTA), and deoxynivalenol (DON). Pet food products (n = 58) marketed for dogs, cats, birds, and rabbits were tested in duplicate with ELISA, and results above the limit of quantitation were confirmed using liquid chromatography tandem mass spectrometry (LC-MS/MS). OTA was detected in one product (rabbit food) and AFs were detected in two products (one dog treat and one bird treat). In contrast, DON was detected in the majority (74%) of products tested. Bird and rabbit products were the most affected by DON, with levels above 0.5 µg/g in 50 and 80% of samples, respectively. One rabbit sample tested positive for both OTA and DON. Overall, the findings of this study revealed a low incidence of AFs and OTA in commercial pet food. Although DON was detected in numerous products, the levels were well below those associated with acute toxic effects.

Effects of climate change on the persistence and dispersal of foodborne bacterial pathogens in the outdoor environment: A review.

According to the Intergovernmental Panel on Climate Change (IPCC), warming of the climate system is unequivocal. Over the coming century, warming trends such as increased duration and frequency of heat waves and hot extremes are expected in some areas, as well as increased intensity of some storm systems. Climate-induced trends will impact the persistence and dispersal of foodborne pathogens in myriad ways, especially for environmentally ubiquitous and/or zoonotic microorganisms. Animal hosts of foodborne pathogens are also expected to be impacted by climate change through the introduction of increased physiological stress and, in some cases, altered geographic ranges and seasonality. This review article examines the effects of climatic factors, such as temperature, rainfall, drought and wind, on the environmental dispersal and persistence of bacterial foodborne pathogens, namely, Bacillus cereus, Brucella, Campylobacter, Clostridium, Escherichia coli, Listeria monocytogenes, Salmonella, Staphylococcus aureus, Vibrio and Yersinia enterocolitica. These relationships are then used to predict how future climatic changes will impact the activity of these microorganisms in the outdoor environment and associated food safety issues. The development of predictive models that quantify these complex relationships will also be discussed, as well as the potential impacts of climate change on transmission of foodborne disease from animal hosts.

A DNA Mini-Barcoding System for Authentication of Processed Fish Products.

Species substitution is a form of seafood fraud for the purpose of economic gain. DNA barcoding utilizes species-specific DNA sequence information for specimen identification. Previous work has established the usability of short DNA sequences-mini-barcodes-for identification of specimens harboring degraded DNA. This study aims at establishing a DNA mini-barcoding system for all fish species commonly used in processed fish products in North America. Six mini-barcode primer pairs targeting short (127-314 bp) fragments of the cytochrome c oxidase I (CO1) DNA barcode region were developed by examining over 8,000 DNA barcodes from species in the U.S. Food and Drug Administration (FDA) Seafood List. The mini-barcode primer pairs were then tested against 44 processed fish products representing a range of species and product types. Of the 44 products, 41 (93.2%) could be identified at the species or genus level. The greatest mini-barcoding success rate found with an individual primer pair was 88.6% compared to 20.5% success rate achieved by the full-length DNA barcode primers. Overall, this study presents a mini-barcoding system that can be used to identify a wide range of fish species in commercial products and may be utilized in high throughput DNA sequencing for authentication of heavily processed fish products.

Microbial safety and quality of fresh herbs from Los Angeles, Orange County and Seattle farmers' markets.

BACKGROUND: Farmers' markets have been growing in popularity in the United States, but the microbial quality and safety of the food sold at these markets is currently unknown. The purpose of this study was to assess the microbial safety and quality of fresh basil, parsley and cilantro sold at farmers' markets in the Los Angeles, Orange County and greater Seattle areas. RESULTS: A total of 133 samples (52 basil, 41 cilantro and 40 parsley) were collected from 13 different farmers' markets and tested for Salmonella and generic Escherichia coli. One sample (parsley) was confirmed positive for Salmonella and 24.1% of samples were positive for generic E. coli, with a range of 0.70-3.15 log CFU g(-1) . Among the herbs tested, basil showed the highest percentage of samples with generic E. coli (26.9%), followed by cilantro (24.4%) and then parsley (20.0%). For 12% of samples, the levels of generic E. coli exceeded guidelines established by the Public Health Laboratory Service for microbiological quality of ready-to-eat foods. CONCLUSION: Overall, this study indicates the presence of Salmonella and generic E. coli in fresh herbs sold at farmers' markets; however, additional studies are needed to determine the sources and extent of contamination.

Rapid detection and differentiation of human noroviruses using RT-PCR coupled to electrospray ionization mass spectrometry.

The goal of this study was to develop an assay for the detection and differentiation of noroviruses using RT-PCR followed by electrospray ionization mass spectrometry (ESI-MS). Detection of hepatitis A virus was also considered. Thirteen primer pairs were designed for use in this assay and a reference database was created using GenBank sequences and reference norovirus samples. The assay was tested for inclusivity and exclusivity using 160 clinical norovirus samples, 3 samples of hepatitis A virus and 3 other closely related viral strains. Results showed that the assay was able to detect norovirus with a sensitivity of 92% and a specificity of 100%. Norovirus identification at the genogroup level was correct for 98% of samples detected by the assay and for 75% of a subset of samples (n = 32) compared at the genotype level. Identification of norovirus genotypes is expected to improve as more reference samples are added to the database. The assay was also capable of detecting and genotyping hepatitis A virus in all 3 samples tested. Overall, the assay developed here allows for detection and differentiation of noroviruses within one working day and may be used as a tool in surveillance efforts or outbreak investigations.