Foodborne Outbreaks Research Articles

Minimally Processed Vegetables in Brazil: An Overview of Marketing, Processing, and Microbiological Aspects.

The global demand for minimally processed vegetables (MPVs) has grown, driven by changes in the population's lifestyle. MPVs are fresh vegetables that undergo several processing steps, resulting in ready-to-eat products, providing convenience for consumers and food companies. Among the processing steps, washing-disinfection plays an important role in reducing the microbial load and eliminating pathogens that may be present. However, poor hygiene practices can jeopardize the microbiological quality and safety of these products, thereby posing potential risks to consumer health. This study provides an overview of minimally processed vegetables (MPVs), with a specific focus on the Brazilian market. It includes information on the pricing of fresh vegetables and MPVs, as well as an examination of the various processing steps involved, and the microbiological aspects associated with MPVs. Data on the occurrence of hygiene indicators and pathogenic microorganisms in these products are presented. The focus of most studies has been on the detection of Escherichia coli, Salmonella spp., and Listeria monocytogenes, with prevalence rates ranging from 0.7% to 100%, 0.6% to 26.7%, and 0.2% to 33.3%, respectively. Foodborne outbreaks associated with the consumption of fresh vegetables in Brazil between 2000 and 2021 were also addressed. Although there is no information about whether these vegetables were consumed as fresh vegetables or MPVs, these data highlight the need for control measures to guarantee products with quality and safety to consumers.

Whole-genome sequencing of Listeria monocytogenes isolated from the first listeriosis foodborne outbreak in South Korea.

Listeria monocytogenes is a foodborne pathogen that causes listeriosis in humans with severe symptoms. In South Korea, listeriosis had only been reported sporadically among hospitalized patients until the first foodborne outbreak occurred in 2018. In this study, a L. monocytogenes strain responsible for this outbreak (FSCNU0110) was characterized via whole genome sequencing and compared with publicly available L. monocytogenes genomes of the same clonal complex (CC). Strain FSCNU0110 belonged to multilocus sequence typing (MLST)-based sequence type 224 and CC224, and core genome MLST-based sublineage 6,178. The strain harbored tetracycline resistance gene tetM, four other antibiotic resistance genes, and 64 virulence genes, including Listeria pathogenicity island 1 (LIPI-1) and LIPI-3. Interestingly, llsX in LIPI-3 exhibited a characteristic SNP (deletion of A in position 4, resulting in a premature stop codon) that was missing among all CC224 strains isolated overseas but was conserved among those from South Korea. In addition, the tetM gene was also detected only in a subset of CC224 strains from South Korea. These findings will provide an essential basis for assessing the characteristics of CC224 strains in South Korea that have shown a potential to cause listeriosis outbreaks.

Tolerance Increase in Escherichia coli O157:H7 and Methicillin-Resistant Staphylococcus Aureus USA300 Exposed to Low-Power Continuous Ultraviolet Radiation from Narrow-Wavelength Sources

Escherichia coli O157:H7 is a major cause of foodborne disease outbreaks throughout the world, while methicillin-resistant Staphylococcus aureus (MRSA) is responsible for many difficult-to-treat infections in humans. Ultraviolet (UV) irradiation is commonly used for disinfection in food processing, medical facilities, and water treatment to prevent the transmission of these pathogen. With increased use of UV disinfection technologies over the last few years because of COVID-19 and concerns about other communicable disease, it has become a concern that microbial species could develop tolerance to UV irradiation, especially when it is applied continuously. To elucidate the effect of continuous UV exposure at different wavelengths and power levels on the tolerance development of bacteria, Escherichia coli O157:H7 and MRSA)USA300 growths were investigated by continuously exposing inoculated agar plates to six different commercially available UV sources at wavelengths of 222 nm, 254 nm, 275 nm, and 405 nm. The agar plates in these experiments were partially covered by a thin acrylic sheet, which provided either complete protection from the UV to the cells directly under the sheet, no protection if significantly away from the sheet, or partial protection near the edges of the sheet due to shading or small amounts of UV reflection under the sheet at the edges. In these experiments, tolerant cells of E. coli and S. aureus were found from the 222 nm, the 405 nm, and one of the 254 nm sources. Upon examination of the power of each UV source, it was shown that the 275 nm and 254 nm sources that resulted in no tolerant cells had surface power densities [at 25 cm (10 in.)] that were more than 10–200 times greater than those that had tolerant cells. These results suggests that bacterial cells have a higher chance to develop UV tolerance under lower power UV sources (under the experimental conditions in our laboratory). Genome investigation of the tolerant colonies revealed that there are no significant differences between the cells that developed tolerance and the original organism, hinting at the need to explore the role of epigenetics mechanisms in the development of UV tolerance in these bacteria.

Biofilm formation in food processing plants and novel control strategies to combat resistant biofilms: the case of Salmonella spp.

Salmonella is one of the pathogens that cause many foodborne outbreaks throughout the world, representing an important global public health problem. Salmonella strains with biofilm-forming abilities have been frequently isolated from different food processing plants, especially in poultry industry. Biofilm formation of Salmonella on various surfaces can increase their viability, contributing to their persistence in food processing environments and cross-contamination of food products. In recent years, increasing concerns arise about the antimicrobial resistant and disinfectant tolerant Salmonella, while adaptation of Salmonella in biofilms to disinfectants exacerbate this problem. Facing difficulties to inhibit or remove Salmonella biofilms in food industry, eco-friendly and effective strategies based on chemical, biotechnological and physical methods are in urgent need. This review discusses biofilm formation of Salmonella in food industries, with emphasis on the current available knowledge related to antimicrobial resistance, together with an overview of promising antibiofilm strategies for controlling Salmonella in food production environments.

IRIDA-ARIES Genomics, a key player in the One Health surveillance of diseases caused by infectious agents in Italy.

Pathogen genomics is transforming surveillance of infectious diseases, deepening our understanding of evolution and diffusion of etiological agents, host-pathogen interactions and antimicrobial resistance. This discipline is playing an important role in the development of One Health Surveillance with public health experts of various disciplines integrating methods applied to pathogen research, monitoring, management and prevention of outbreaks. Especially with the notion that foodborne diseases may not be transmitted by food only, the ARIES Genomics project aimed to deliver an Information System for the collection of genomic and epidemiological data to enable genomics-based surveillance of infectious epidemics, foodborne outbreaks and diseases at the animal-human interface. Keeping in mind that the users of the system comprised persons with expertise in a wide variety of domains, the system was expected to be used with a low learning curve directly by the persons target of the analyses' results, keeping the information exchange chains as short as possible. As a result, the IRIDA-ARIES platform (https://irida.iss.it/) provides an intuitive web-based interface for multisectoral data collection and bioinformatic analyses. In practice, the user creates a sample and uploads the Next-generation sequencing reads, then an analysis pipeline is launched automatically performing a series of typing and clustering operations fueling the information flow. Instances of IRIDA-ARIES host the Italian national surveillance system for infections by Listeria monocytogenes (Lm) and the surveillance system for infections by Shigatoxin-producing Escherichia coli (STEC). As of today, the platform does not provide tools to manage epidemiological investigations but serves as an instrument of aggregation for risk monitoring, capable of triggering alarms on possible critical situations that might go unnoticed otherwise.

Recent trends in the use of bacteriophages as replacement of antimicrobials against food-animal pathogens.

A major public health impact is associated with foodborne illnesses around the globe. Additionally, bacteria are becoming more resistant to antibiotics, which pose a global threat. Currently, many scientific efforts have been made to develop and implement new technologies to combat bacteria considering the increasing emergence of multidrug-resistant bacteria. In recent years, there has been considerable interest in using phages as biocontrol agents for foodborne pathogens in animals used for food production and in food products themselves. Foodborne outbreaks persist, globally, in many foods, some of which lack adequate methods to control any pathogenic contamination (like fresh produce). This interest may be attributed both to consumers' desire for more natural food and to the fact that foodborne outbreaks continue to occur in many foods. Poultry is the most common animal to be treated with phage therapy to control foodborne pathogens. A large number of foodborne illnesses worldwide are caused by Salmonella spp. and Campylobacter, which are found in poultry and egg products. Conventional bacteriophage-based therapy can prevent and control humans and animals from various infectious diseases. In this context, describing bacteriophage therapy based on bacterial cells may offer a breakthrough for treating bacterial infections. Large-scale production of pheasants may be economically challenging to meet the needs of the poultry market. It is also possible to produce bacteriophage therapy on a large scale at a reduced cost. Recently, they have provided an ideal platform for designing and producing immune-inducing phages. Emerging foodborne pathogens will likely be targeted by new phage products in the future. In this review article, we will mainly focus on the Bacteriophages (phages) that have been proposed as an alternative strategy to antibiotics for food animal pathogens and their use for public health and food safety.

Bacteria and poisonous plants/fungi were the primary causative hazards of foodborne disease outbreaks: A five-year survey from Guangzhou, Guangdong

The burden of foodborne diseases is of serious concern. More effective and localized intervention policies for outbreak prevention and management are required; however, policy modification is hampered due to a lack of information on the epidemiological characteristics of outbreaks in Guangzhou. We collected data from 182 foodborne disease outbreaks reported in Guangzhou, China from 2017 to 2021 to investigate the epidemiological characteristics and associated factors. Nine outbreaks were serious enough to be labelled as level IV public health emergencies, all of which were associated with canteens. In terms of the number of outbreaks, morbidity and clinical medical needs, bacteria and poisonous plants/fungi were the primary causative hazards of outbreaks, and were found mostly in foodservice establishments (96 %, 95/99) and private homes (86 %, 37/43) respectively. Surprisingly, Vibrio parahaemolyticus was primarily identified in meat and poultry products rather than in aquatic products in these outbreaks. Patient specimens and food samples were among the most common sources of detected pathogens in foodservice establishments and private homes. Cross-contamination (35 %), improper processing (32 %) and equipment/utensil contamination (30 %) were the top three risk factors for outbreaks related to foodservice establishments, while accidental ingestion of poisonous food (78 %) was the most common risk factor in private homes. Based on the above epidemiological characteristics of the outbreaks, key foodborne disease intervention policy points should be to raise public awareness of harmful food and avoid risk behaviour, improve handler hygiene training, and strengthen the hygiene management and supervision of kitchens, especially canteens in collective units.

Development and application of fruit and vegetable based green films with natural bio-actives in meat and dairy products: A review.

In recent years, food-borne outbreaks and food plastic waste accumulation in the environment have impelled a hunt for new, sustainable, novel and innovatory food packaging interventions to face microbial contamination, food quality and safety. Pollution caused from wastes generated by agricultural activities is one of chief rising concerns of the environmentalists across the globe. A solution to this problem is effective and economic valorization of residues from agriculture sector. It would ensure that the by-products / residues from one activity act as ingredients/ raw materials for another industry. An example is fruit and vegetable waste based green films for food packaging. Edible packaging is a well-researched area of science where numerous biomaterials have been already explored. Along with dynamic barrier properties, these biofilms often exhibit antioxidant and antimicrobial properties as function of the bioactive additives (like essential oils) often incorporated in them. Additionally, these films are made competent by use of recent technologies (like encapsulation, nano-emulsions, radio-sensors) to ensure high end performance and meet the principles of sustainability. Livestock products like meat, poultry and dairy products are highly perishable and depend largely upon the mercy of packaging materials to enhance their shelf life. In this review, all the above-mentioned aspects are thoroughly covered with a view to project FVBGFs as a potential and viable packaging material for livestock products, along with a discussion on role of bio-additives, technological interventions, properties and potential applications of FVBGFs in livestock products. This article is protected by copyright. All rights reserved.

T-cell receptor Vβ8 for detection of biologically active streptococcal pyrogenic exotoxin type C

Streptococcus pyogenes is an important human pathogen, commonly spread by airborne droplets but also by ingestion of contaminated food. Apart from causing infection, this pathogen produces 13 distinct types of streptococcal pyrogenic exotoxins (SPEs). The current method for detection cannot distinguish between the biologically active form of SPEs that has been reported to cause foodborne outbreaks and the inactivated toxin which poses no health risk. To measure the biological activity of SPE-C, one such toxin that was linked to foodborne outbreaks associated with milk and milk products, we developed a cell-based assay that can discern between biologically active and inactive SPE-C. To the best of our knowledge, this is the first showing that SPE-C activates T-cells expressing Vβ8. With this finding, we used a T-cell line natively expressing Vβ8 that was genetically engineered to also express the luciferase reporter gene under the regulation of nuclear factor of activated T-cells response element (NFAT-RE) in combination with a B-cell line to present the rSPE-C toxin via MHC class II to the Vβ8 TCR in an assay to detect and to discern between biologically active and inactive rSPE-C. By using this system, we demonstrated that SPE-C induced significant IL-2 secretion after 72 h and visible light emission after only 5 h, doubling by 24 h. We utilize this finding to assess the specificity of the assay and the effect of pasteurization on SPE-C activity. We observed no cross reactivity with SPE-B and significant loss of SPE-C biologically activity in spiked PBS while SPE-C spiked into milk is heat stable. Once SPE-C has formed, it is infeasible to eliminate it from milk by thermal treatment.

Classification between live and dead foodborne bacteria with hyperspectral microscope imagery and machine learning

Identifying live foodborne bacteria is essential for ensuring food safety and preventing foodborne illnesses. This study investigated the use of hyperspectral microscope imaging and deep learning methods to accurately distinguish between live and dead foodborne bacteria based on their spectral and morphological features. Three deep learning models, Fusion-Net I, II, and III, were developed and evaluated for their ability to classify live and dead bacterial cells of six pathogenic strains, including Escherichia coli (EC), Listeria innocua (LI), Staphylococcus aureus (SA), Salmonella Enteritidis (SE), Salmonella Heidelberg (SH), and Salmonella Typhimurium (ST). The models utilized both morphological and spectral characteristics of the bacterial cells, with inputs of average spectra and 546 nm band images. Fusion-Net I achieved high accuracy in identifying live bacterial cells, with a classification accuracy of 100% for LI, SE, ST strains and over 92.9% for EC, SA, SH. Fusion-Net II and III models were even more robust, achieving 100% accuracy consistently in classifying dead cells in all six strains. Fusion-Net III also showed the ability to identify bacterial strains with 96.9% accuracy, making it a dual-task model with potential applications in identifying live foodborne bacteria prior to foodborne outbreaks. These findings suggest that the use of hyperspectral microscope imaging and deep learning methods could provide a new tool for quickly and accurately identifying bacterial viability, thereby improving the efficiency and reliability of food safety inspection.

Multinational Outbreak of Listeria monocytogenes Infections Linked to Enoki Mushrooms Imported from the Republic of Korea 2016–2020

Keeping the global food supply safe necessitates international collaborations between countries. Health and regulatory agencies routinely communicate during foodborne illness outbreaks, allowing partners to share investigational evidence. A 2016–2020 outbreak of Listeria monocytogenes infections linked to imported enoki mushrooms required a multinational collaborative investigation among the United States, Canada, Australia, and France. Ultimately, this outbreak included 48 ill people, 36 in the United States and 12 in Canada, and was linked to enoki mushrooms sourced from one manufacturer located in the Republic of Korea. Epidemiologic, laboratory, and traceback evidence led to multiple regulatory actions, including extensive voluntary recalls by three firms in the United States and one firm in Canada. In the United States and Canada, the Korean manufacturer was placed on import alert while other international partners provided information about their respective investigations and advised the public not to eat the recalled enoki mushrooms. The breadth of the geographic distribution of this outbreak emphasizes the global reach of the food industry. This investigation provides a powerful example of the impact of national and international coordination of efforts to respond to foodborne illness outbreaks and protect consumers. It also demonstrates the importance of fast international data sharing and collaboration in identifying and stopping foodborne outbreaks in the global community. Additionally, it is a meaningful example of the importance of food sampling, testing, and integration of sequencing results into surveillance databases.

Survival kinetics of Listeria monocytogenes and Salmonella enterica on dehydrated enoki and wood ear mushrooms during long-term storage

Two specialty mushrooms have recently become novel vectors for foodborne outbreaks in the U.S.: fresh enoki and dried wood ear mushrooms were linked to a listeriosis and salmonellosis outbreak, respectively. The aim of this study was to evaluate the survival kinetics of Listeria monocytogenes and Salmonella enterica on dehydrated enoki and wood ear mushrooms during long-term storage. Following heat dehydration, mushrooms were inoculated with either L. monocytogenes or S. enterica, allowed to dry for 1 h, and then stored for up to 180 d at 25 °C and 33% relative humidity. Both pathogens were enumerated from the mushrooms at intervals during the storage period. Survival kinetics of both pathogens were modeled using both the Weibull and log-linear with tail models. After inoculation and 1 h drying, both pathogen populations decreased 2.26–2.49 log CFU/g on wood ear mushrooms; no decrease was observed on enoki. Both pathogens survived during storage on both mushroom types. On wood ear mushrooms, a 2-log decrease of both pathogens occurred during storage. On enoki mushrooms, 4-log decreases of both pathogens were modeled to occur after 127.50–156.60 d. The results of this study suggest that L. monocytogenes and S. enterica can persist on dehydrated specialty mushrooms during long-term storage.

Salmonella Outbreaks Associated with Not Ready-to-Eat Breaded, Stuffed Chicken Products — United States, 1998–2022

Not ready-to-eat (NRTE) breaded, stuffed chicken products (e.g., chicken stuffed with broccoli and cheese) typically have a crispy, browned exterior that can make them appear cooked. These products have been repeatedly linked to U.S. salmonellosis outbreaks, despite changes to packaging initiated in 2006 to identify the products as raw and warn against preparing them in a microwave oven (microwave) (1-4). On April 28, 2023, the U.S. Department of Agriculture proposed to declare Salmonella an adulterant* at levels of one colony forming unit per gram or higher in these products (5). Salmonella outbreaks associated with NRTE breaded, stuffed chicken products during 1998-2022 were summarized using reports in CDC's Foodborne Disease Outbreak Surveillance System (FDOSS), outbreak questionnaires, web postings, and data from the Minnesota Department of Health (MDH)† and the U.S. Department of Agriculture's Food Safety and Inspection Service (FSIS). Eleven outbreaks were identified in FDOSS. Among cultured samples from products obtained from patients' homes and from retail stores during 10 outbreaks, a median of 57% of cultures per outbreak yielded Salmonella. The NRTE breaded, stuffed chicken products were produced in at least three establishments.§ In the seven most recent outbreaks, 0%-75% of ill respondents reported cooking the product in a microwave and reported that they thought the product was sold fully cooked or did not know whether it was sold raw or fully cooked. Outbreaks associated with these products have occurred despite changes to product labels that better inform consumers that the products are raw and provide instructions on safe preparation, indicating that consumer-targeted interventions are not sufficient. Additional Salmonella controls at the manufacturer level to reduce contamination in ingredients might reduce illnesses attributable to NRTE breaded, stuffed chicken products.

Ion transport basis of norovirus diarrhea in a neonatal mouse model

Background: Human Norovirus (HuNoV) is the leading cause of infectious gastroenteritis and food-borne outbreaks, responsible for over 220K deaths annually. Given difficulties studying HuNoV, Murine Norovirus (MNV) has been used as a model for norovirus (NoV) pathophysiology. A major barrier to understand how NoV causes diarrhea is the absence of diarrhea in adult wild-type (WT) mice, which have asymptomatic MNV infections. While several KO mouse strains (e.g., STAT1) have been employed to recapitulate disease, these mice often have exaggerated, systemic, and lethal disease courses that imperfectly match human disease. Very recently, a new model of MNV that appears to recapitulate symptomatic HuNoV infection has been established. This model involves the oral gavage of three- or four-day-old (d.o.) WT BALB/c mice with high-concentrations of MNV resulting in a diarrheal phenotype. Current studies were undertaken to understand the ion transport basis of MNV diarrhea using this novel model. Methods: Three to four d.o. BALB/c pups were gavaged with either 1x10 8 plaque-forming units (PFU) of MNV-1 (CW3) or PBS alone followed by sacrifice at 48 hours-post-gavage (hpg). Small and large intestines were harvested for RNA and immunofluorescence (IF) analysis of multiple ion transporters that have been linked to diarrhea in other disease models. Results: MNV-gavaged pups had loose, orange stools, consistent with a diarrheal phenotype observed previously with this model. MNV RNA was detectable in small and large intestinal tissue for CW3-gavaged vs mock-gavaged pups (p-values <0.05) demonstrating successful infection with MNV. MNV infection had no significant effect on transcript levels of various electrolyte and nutrient transporters including DRA, NHE3, PAT-1, Na-K-ATPase, or SGLT-1. However, we found significant increases in CFTR and Vasoactive intestinal peptide receptor 1 (VPAC1) transcripts (p <0.05 and 0.01, respectively) and a significant increase in CFTR IF staining in frozen sections of the SI over mock (p<0.01). We did not find a significant increase in VIP transcript, VPAC1 protein expression or immunofluorescent staining, nor nuclear localization of pCREB in SI frozen sections. Conclusion: Using this novel neonatal WT BALB/c MNV mouse model to evaluate the effect of infection on gene transcription, and protein expression and localization of ion transporters commonly implicated in diarrhea, we observed significant increases in CFTR and VPAC1 SI gene expression in CW3-gavaged pups with negligible changes in transcription of all other transporters examined in this study. In addition, apical and total CFTR staining increased significantly without changes in VPAC1 or pCREB nuclear localization in frozen SI sections of CW3-gavaged pups compared to mock, suggesting that MNV causes a CFTR-mediated secretory diarrhea in the absence of changes in VPAC1 protein expression, localization, or activation. These studies were supported by the Department of Veterans Affairs, Veterans Heath Administration, Office of Research and Development, Biomedical Laboratory Research and Development: Merit Review Award: BX002011 (PKD), and VA Senior Research Career Scientist Award:1IK6BX005242 (PKD). The studies were also supported by NIH/NIDDK grants, R01 DK54016 and DK92441 (PKD). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Expression of Concern: Comparative phenotypic, genotypic and genomic analyses of Bacillus thuringiensis associated with foodborne outbreaks in France.

Expression of Concern: Comparative phenotypic, genotypic and genomic analyses of Bacillus thuringiensis associated with foodborne outbreaks in France.

Impact of Training on Employees' Handwashing Behaviors in School Nutrition Programs.

School nutrition employee behavior plays an important role in preventing foodborne outbreaks and protecting the almost 30 million children who partake in daily school lunch. The study aim was to compare the impact of using a food safety training program with or without using a realistic-event video on handwashing behavior modification for school nutrition employees. A 2-group (control and experimental) pretest with 2 post-tests design was used. The control group received training without the video and the experimental group received the food safety training with a realistic-event video. Measurements used to address the purpose and objectives of this study included questionnaires and direct observations. The sample consisted of 443 school nutrition employees responsible for food preparation and service affiliated with 21 school districts in 18 states. Approximately half of the sample attended the original unmodified training and the other half attended the modified training. Data were collected in the United States during 2017. A total of 338 employees participated in the observations and 443 participants completed the questionnaires during the 3 phases; 935 questionnaires were used for the analysis. The intervention involved a food safety training program embedded with a realistic-event video related to handwashing. The video used previous research to target antecedents to handwashing behavior among participants. Actual behavior was observed across 3 phases-pretraining, post training, and final-for both the control and experimental groups. In addition, indirect and direct measures of behavioral intentions for handwashing were measured. For the observation data, a 2-way, fixed-effects, mixed-model procedure was used to analyze the data. Simple and multiple linear regression and contingency table analyses looking for differences among phases and treatments were used for questionnaire data analysis. Most practices were reported as in compliance (51.3% to 80.6%) for both the control and experimental groups during all phases. The experimental group had a higher behavioral intention of properly washing their hands than participants in the control group. The results showed that handwashing practices were in compliance most of the time for both the control and experimental groups during all 3 observation periods. Differences among the data collection periods on the theory of planned behavior constructs indicated no statistical effect of the treatment (exposure to the video) between the control and intervention groups.

Non-spherical gold nanoparticles enhanced fluorescence of carbon dots for norovirus-like particles detection

BackgroundNorovirus is a common pathogen that causes foodborne outbreaks every year and the increasing number of deaths caused by it has become a substantial concern in both developed and underdeveloped countries. To date, no vaccines or drugs are able to control the outbreak, highlighting the importance of finding specific, and sensitive detection tools for the viral pathogen. Current diagnostic tests are limited to public health laboratories and/or clinical laboratories and are time-consuming. Hence, a rapid and on-site monitoring strategy for this disease is urgently needed to control, prevent and raise awareness among the general public.ResultsThe present study focuses on a nanohybridization technique to build a higher sensitivity and faster detection response to norovirus-like particles (NLPs). Firstly, the wet chemical-based green synthesis of fluorescent carbon quantum dots and gold nanoparticles (Au NPs) has been reported. Then, a series of characterization studies were conducted on the synthesized carbon dots and Au NPs, for example, high-resolution transmission emission microscopy, fluorescence spectroscopy, fluorescence life-lime measurement, UV–visible spectroscopy, and X-ray diffraction (XRD). The fluorescence emission of the as-synthesized carbon dots and the absorption of Au NPs were located at 440 nm and 590 nm, respectively. Then, the plasmonic properties of Au NPs were utilized to enhance the fluorescence emission of carbon dots in the presence of NLPs in human serum. Here, the enhanced fluorescence response was linearly correlated up to 1 μg mL−1. A limit of detection (LOD) value was calculated to be 80.3 pg mL−1 demonstrating that the sensitivity of the proposed study is 10 times greater than that of the commercial diagnostic kits.ConclusionsThe proposed exciton-plasmon interaction-based NLPs-sensing strategy was highly sensitive, specific, and suitable for controlling upcoming outbreaks. Most importantly, the overall finding in the article will take the technology a step further to applicable point-of-care (POC) devices.

Irradiation as a Promising Technology to Improve Bacteriological and Physicochemical Quality of Fish.

Fish is an excellent source of protein and other essential minerals and vitamins; nevertheless, several food-borne disease outbreaks have been linked to the consumption of different types of fish. Therefore, we aimed to overcome these health threats by evaluating gamma radiation as a good fish preservation method. The aerobic plate count (APC), identification of most common pathogenic bacteria, organoleptic properties, proximate composition, and other chemical evaluations were detected in both untreated and gamma-treated fish. The overall grades of organoleptic evaluations ranged from good to very good. Fortunately, the overall chemical analysis of all examined fish samples was accepted. For the untreated fish samples, the APC was within and above the permissible limit (5 × 107 CFU/g). Pathogenic bacteria were detected with a high prevalence rate, especially S. aureus, which was found in high percentages among examined untreated fish samples. Regarding the treated fish samples, APC and pathogenic bacterial counts were reduced in a dose-dependent manner, and the irradiation at dose 5 KGy resulted in complete eradication of the aerobic plate count (not detectable) with a mean reduction percentage equal to 100%. However, gamma irradiation has no significant effect on proximate composition; particularly, carbohydrates, proteins, and lipids were not significantly affected by low and medium doses of radiation. Therefore, gamma irradiation is a highly effective fish preservation method without any effect on fish quality. Additionally, gamma irradiation as a cold process is an attractive technology for solving the problem arising from fish-borne pathogens, and it has been purposed in this study as a cheap and safe method for reducing microbial contamination of fish.

Amplicon-Based High-Throughput Sequencing Method for Genotypic Characterization of Norovirus in Oysters.

Norovirus is a highly diverse RNA virus often implicated in foodborne outbreaks, particularly those associated with shellfish. Shellfish are filter feeders, and when harvested in bays exposed to wastewater overflow or storm overflows, they can harbor various pathogens, including human-pathogenic viruses. The application of Sanger or amplicon-based high-throughput sequencing (HTS) technologies to identify human pathogens in shellfish faces two main challenges: (i) distinguishing multiple genotypes/variants in a single sample and (ii) low concentrations of norovirus RNA. Here, we assessed the performance of a novel norovirus capsid amplicon HTS method. We generated a panel of spiked oysters containing various norovirus concentrations with different genotypic compositions. Several DNA polymerases and reverse transcriptases (RTs) were compared, and performance was evaluated based on (i) the number of reads passing quality filters per sample, (ii) the number of correct genotypes identified, and (iii) the sequence identity of outputs compared to Sanger-derived sequences. A combination of the reverse transcriptase LunaScript and the DNA polymerase AmpliTaq Gold provided the best results. The method was then employed, and compared with Sanger sequencing, to characterize norovirus populations in naturally contaminated oysters. IMPORTANCE While foodborne outbreaks account for approximately 14% of norovirus cases (L. Verhoef, J. Hewitt, L. Barclay, S. Ahmed, R. Lake, A. J. Hall, B. Lopman, A. Kroneman, H. Vennema, J. Vinjé, and M. Koopmans, Emerg Infect Dis 21:592-599, 2015), we do not have standardized high-throughput sequencing methods for genotypic characterization in foodstuffs. Here, we present an optimized amplicon high-throughput sequencing method for the genotypic characterization of norovirus in oysters. This method can accurately detect and characterize norovirus at concentrations found in oysters grown in production areas impacted by human wastewater discharges. It will permit the investigation of norovirus genetic diversity in complex matrices and contribute to ongoing surveillance of norovirus in the environment.

Insertion sequences mediate clinical ST34 monophasic Salmonella enterica serovar Typhimurium plasmid polymorphism

Hybrid plasmids can combine the genetic elements of multiple plasmids, with the potential to carry a variety of antibiotic resistance genes and virulence genes, causing a great public health concern. Hybrid plasmids formed by fusion events may further exacerbate the spread of antibiotic resistance genes as well as plasmid evolution. Salmonella enterica serovar 4,[5],12:i:- is a monophasic variant of S. Typhimurium, which is one of the major causes of foodborne disease outbreaks worldwide. To assess the risk of transmission due to plasmid structure changes, we investigated the structural diversity of plasmids in two S. 4,[5],12:i:- isolates. Nanopore long-read sequencing was performed for plasmid comparison between original plasmids (donor isolates) and reorganized plasmids. We found that the IncHI2-IncHI2A multidrug resistance (MDR) plasmids in S. 4,[5],12:i:- possessed high plasticity, and could undergo recombination with other plasmids to form fusion plasmids of different sizes. Plasmid structural polymorphisms were mainly mediated by insertion sequences such as IS26 and ISPa40, and led to the rearrangement of the plasmid internal structures. To the best of our knowledge, this is the first report of the fusion of the IncHI2-IncHI2A and IncB/O/K/Z plasmids in S. 4,[5],12:i:- mediated by IS26. In addition, we also found that the mcr-1 gene was able to generate duplication during conjugation. Polymorphic changes in MDR plasmids during conjugation may further reduce the choice of clinical therapeutic agents. Therefore, continuous monitoring regarding plasmid polymorphic changes during transmission in both in vitro and in vivo is urgently needed to decipher the MDR plasmid evolution.