Prevalence and antimicrobial susceptibility of major foodborne pathogens in imported seafood

Extended Spectrum β-Lactamase-Producing Enterobacterales of Shrimp and Salmon Available for Purchase by Consumers in Canada-A Risk Profile Using the Codex Framework

The extended-spectrum β-lactamase (ESBL)-producing Enterobacterales (ESBL-EB) encompass several important human pathogens and are found on the World Health Organization (WHO) priority pathogens list of antibiotic-resistant bacteria. They are a group of organisms which demonstrate resistance to third-generation cephalosporins (3GC) and their presence has been documented worldwide, including in aquaculture and the aquatic environment. This risk profile was developed following the Codex Guidelines for Risk Analysis of Foodborne Antimicrobial Resistance with the objectives of describing the current state of knowledge of ESBL-EB in relation to retail shrimp and salmon available to consumers in Canada, the primary aquacultured species consumed in Canada. The risk profile found that Enterobacterales and ESBL-EB have been found in multiple aquatic environments, as well as multiple host species and production levels. Although the information available did not permit the conclusion as to whether there is a human health risk related to ESBLs in Enterobacterales in salmon and shrimp available for consumption by Canadians, ESBL-EB in imported seafood available at the retail level in Canada have been found. Surveillance activities to detect ESBL-EB in seafood are needed; salmon and shrimp could be used in initial surveillance activities, representing domestic and imported products.

Antimicrobial Resistance, Virulence Properties and Genetic Diversity of Salmonella Typhimurium Recovered from Domestic and Imported Seafood

The quantity of seafood imported and produced by domestic aquaculture farming has increased. Recently, it has been reported that multidrug-resistant (MDR) Salmonella Typhimurium may be associated with seafood. However, information is limited to the antimicrobial resistance, virulence properties, and genetic diversity of S. Typhimurium recovered from imported and domestic seafood. This study investigated the antimicrobial resistance, virulence properties, and genetic diversity of S. Typhimurium isolated from domestic and imported catfish, shrimp, and tilapia. A total of 127 isolates were tested for the presence of multidrug-resistance (MDR), virulence genes (invA, pagC, spvC, spvR), and genetic diversity using the Sensititre micro-broth dilution method, PCR, and pulsed-field gel electrophoresis (PFGE), respectively. All isolates were uniformly susceptible to six (amoxicillin/clavulanic acid, ceftiofur, ceftriaxone, imipenem, nitrofurantoin, and trimethoprim/sulfamethoxazole) of the 17 tested antimicrobials and genetically diverse. Fifty-three percent of the Salmonella isolates were resistant to at least one antimicrobial and 49% were multidrug resistant. Ninety-five percent of the isolates possessed the invA gene, 67% pagC, and 43% for both spvC, and spvR. The results suggest that S. Typhimurium recovered from seafood is frequently MDR, virulent, and have the ability to cause salmonellosis.

Prevalence and antimicrobial resistance profiles of Vibrio spp. and Enterococcus spp. in retail shrimp in Northern California

Shrimp is one of the most consumed seafood products globally. Antimicrobial drugs play an integral role in disease mitigation in aquaculture settings, but their prevalent use raises public health concerns on the emergence and spread of antimicrobial resistant microorganisms. Vibrio spp., as the most common causative agents of seafood-borne infections in humans, and Enterococcus spp., as an indicator organism, are focal bacteria of interest for the monitoring of antimicrobial resistance (AMR) in seafood. In this study, 400 samples of retail shrimp were collected from randomly selected grocery stores in the Greater Sacramento, California, area between September 2019 and June 2020. The prevalence of Vibrio spp. and Enterococcus spp. was 60.25% (241/400) and 89.75% (359/400), respectively. Subsamples of Vibrio (n = 110) and Enterococcus (n = 110) isolates were subjected to antimicrobial susceptibility testing (AST). Vibrio isolates had high phenotypic resistance to ampicillin (52/110, 47.27%) and cefoxitin (39/110, 35.45%). Enterococcus were most frequently resistant to lincomycin (106/110, 96.36%), quinupristin-dalfopristin (96/110, 87.27%), ciprofloxacin (93/110, 84.55%), linezolid (86/110, 78.18%), and erythromycin (58/110, 52.73%). For both Vibrio and Enterococcus, no significant associations were observed between multidrug resistance (MDR, resistance to ≥3 drug classes) in isolates from farm raised and wild caught shrimp (p > 0.05) and in isolates of domestic and imported origin (p > 0.05). Whole genome sequencing (WGS) of a subset of Vibrio isolates (n = 42) speciated isolates as primarily V. metschnikovii (24/42; 57.14%) and V. parahaemolyticus (12/42; 28.57%), and detected 27 unique antimicrobial resistance genes (ARGs) across these isolates, most commonly qnrVC6 (19.05%, 8/42), dfrA31 (11.90%, 5/42), dfrA6 (9.5%, 4/42), qnrVC1 (9.5%, 4/42). Additionally, WGS predicted phenotypic resistance in Vibrio isolates with an overall sensitivity of 11.54% and specificity of 96.05%. This study provides insights on the prevalence and distribution of AMR in Vibrio spp. and Enterococcus spp. from retail shrimp in California which are important for food safety and public health and exemplifies the value of surveillance in monitoring the spread of AMR and its genetic determinants.

A systematic review, meta-analysis and meta-regression of the global prevalence of foodborne Vibrio spp. infection in fishes: A persistent public health concern

Human vibriosis, caused by pathogenic Vibrio spp., such as Vibrio parahaemolyticus, Vibrio cholerae and Vibrio vulnificus, has been increasing worldwide, mediated by increasing consumption of seafood. The present study was conducted to examine the global prevalence of V. vulnificus, V. parahaemolyticus and V. cholerae in fishes. We searched PubMed, Web of Science, Scopus, and CNKI for peer-reviewed articles and dissertations prior to December 31, 2021. A total of 24,831 articles were retrieved, and 82 articles contained 61 fish families were included. The global pooled prevalence of V. cholerae, V. parahaemolyticus and V. vulnificus in fishes was 9.56 % (95 % CI: 2.12-20.92), 24.77 % (95 % CI: 17.40-32.93) and 5.29 % (95 % CI: 0.38-13.61), respectively. Subgroup and meta-regression analyses showed that study-level covariates, including temperature, country, continent, origin and detection methods partly explained the between-study heterogeneity. These heterogeneities were underpinned by differences of the three Vibrio spp. in fishes at geographical and climatic scales. These results reveal a high global prevalence of pathogenic Vibrio spp. in fishes and highlight the need for implementation of more effective prevention and control measures to reduce food-borne infection in humans.

Prevalence and Abundance of Bacterial Pathogens of Concern in Shrimp, Catfish and Tilapia Obtained at Retail Stores in Maryland, USA

Outbreaks of human gastroenteritis have been linked to the consumption of contaminated domestic and imported seafood. This study investigated the microbiological quality of seafood obtained from retail stores on the Eastern Shore of Maryland. A total of 440 samples of domestic and imported frozen shrimp, catfish and tilapia samples were analyzed for aerobic plate count (APC), total coliforms, Escherichia coli and seafood-borne-pathogens (Vibrio parahaemolyticus, Vibrio vulnificus, Salmonella, Campylobacter jejuni). The prevalence of APC, coliforms and E. coli positive samples was 100%, 43% and 9.3%, respectively. Approximately 3.2%, 1.4%, 28.9% and 3.6% of the samples were positive for V. parahaemolyticus, V. vulnificus, Salmonella and Campylobacter jejuni, respectively. The MPN/g ranges were 150-1100 MPN/g for vibrios, 10-1100 MPN/g for Salmonella and 93-460 MPN/g for C. jejuni in seafood, respectively. Comparing bacterial prevalence by type or source of seafood, the only significant difference identified was Salmonella-positive imported tilapia (33.3%) versus domestic tilapia (19.4%). The quantitative data on pathogen levels in the present study provide additional information for quantitative risk assessment not available in previous surveys. The findings of this study suggest the association of potential food safety hazards with domestic and imported seafood and warrant further large-scale studies and risk assessment.

Salmonella spp. in Aquaculture: An Exploratory Analysis (Integrative Review) of Microbiological Diagnoses between 2000 and 2020

The present study aimed to characterize, through descriptive statistics, data from scientific articles selected in a systematic integrative review that performed a microbiological diagnosis of Salmonella spp. in aquaculture. Data were obtained from research articles published in the BVS, Scielo, Science Direct, Scopus and Web of Science databases. The selected studies were published between 2000 and 2020 on samples of aquaculture animal production (fish, shrimp, bivalve mollusks, and other crustaceans) and environmental samples of aquaculture activity (farming water, soil, and sediments). After applying the exclusion criteria, 80 articles were selected. Data such as country of origin, categories of fish investigated, methods of microbiological diagnosis of Salmonella spp., sample units analyzed and most reported serovars were mined. A textual analysis of the word cloud and by similarity and descending hierarchical classification with the application of Reinert's algorithm was performed using R® and Iramuteq® software. The results showed that a higher percentage of the selected articles came from Asian countries (38.75%). Fish was the most sampled category, and the units of analysis of the culture water, muscle and intestine were more positive. The culture isolation method is the most widespread, supported by more accurate techniques such as PCR. The most prevalent Salmonella serovars reported were S. Typhimurium, S. Weltevreden and S. Newport. The textual analysis showed a strong association of the terms "Salmonella", "fish" and "water", and the highest hierarchical class grouped 25.4% of the associated text segments, such as "aquaculture", "food" and "public health". The information produced characterizes the occurrence of Salmonella spp. in the aquaculture sector, providing an overview of recent years. Future research focusing on strategies for the control and prevention of Salmonella spp. in fish production are necessary and should be encouraged.

Unraveling the hazardous impact of diverse contaminants in the marine environment: Detection and remedial approach through nanomaterials and nano-biosensors

Marine pollution is one of the most underlooked forms of pollution as it affects most aquatic lives and public health in the coastal area. The diverse form of the hazardous pollutant in the marine ecosystem leads the serious genetic level disorders and diseases which include cancer, diabetes, arthritis, reproductive, and neurological diseases such as Parkinson's, Alzheimer's, and several microbial infections. Therefore, a recent alarming study on these pollutants, the microplastics have been voiced out in many countries worldwide, it was even found to be in the human placenta. In recent times, nanomaterials have demonstrated their potential in the detection and remediation of sensitive contaminants. In this review, we presented a comprehensive overview of the source, and distribution of diverse marine pollution on both aquatic and human health by summarizing the concentration of diverse pollutions (heavy metals, pesticides, microbial toxins, and micro/nano plastics) in marine samples such as soil, water, and seafood. Followed by emphasizing its ecotoxicological impact on aquatic animal life and coastal public health. Also discussed are the applicability and advancements of nanomaterials and nano-based biosensors in the detection, prevention, and remediation of diverse pollution in the marine ecosystem.

Carbapenem-resistant Escherichia coli from shrimp and salmon available for purchase by consumers in Canada: a risk profile using the Codex framework

Resistance to carbapenems in human pathogens is a growing clinical and public health concern. The carbapenems are in an antimicrobial class considered last-resort, they are used to treat human infections caused by multidrug-resistant Enterobacterales, and they are classified by the World Health Organization as 'High Priority Critically Important Antimicrobials'. The presence of carbapenem-resistant Enterobacterales (CREs) of animal-origin is of concern because targeted studies of Canadian retail seafood revealed the presence of carbapenem resistance in a small number of Enterobacterales isolates. To further investigate this issue, a risk profile was developed examining shrimp and salmon, the two most important seafood commodities consumed by Canadians and Escherichia coli, a member of the Enterobacterales order. Carbapenem-resistant E. coli (CREc) isolates have been identified in shrimp and other seafood products. Although carbapenem use in aquaculture has not been reported, several classes of antimicrobials are utilised globally and co-selection of antimicrobial-resistant microorganisms in an aquaculture setting is also of concern. CREs have been identified in retail seafood purchased in Canada and are currently thought to be uncommon. However, data concerning CRE or CREc occurrence and distribution in seafood are limited, and argue for implementation of ongoing or periodic surveillance.

Prevalence of Antimicrobial Resistance in Select Bacteria From Retail Seafood—United States, 2019

In 2019, the United States National Antimicrobial Resistance Monitoring System (NARMS) surveyed raw salmon, shrimp, and tilapia from retail grocery outlets in eight states to assess the prevalence of bacterial contamination and antimicrobial resistance (AMR) in the isolates. Prevalence of the targeted bacterial genera ranged among the commodities: Salmonella (0%–0.4%), Aeromonas (19%–26%), Vibrio (7%–43%), Pseudomonas aeruginosa (0.8%–2.3%), Staphylococcus (23%–30%), and Enterococcus (39%–66%). Shrimp had the highest odds (OR: 2.8, CI: 2.0–3.9) of being contaminated with at least one species of these bacteria, as were seafood sourced from Asia vs. North America (OR: 2.7; CI: 1.8–4.7) and Latin America and the Caribbean vs. North America (OR: 1.6; CI: 1.1–2.3) and seafood sold at the counter vs. sold frozen (OR: 2.1; CI: 1.6–2.9). Isolates exhibited pan-susceptibility (Salmonella and P. aeruginosa) or low prevalence of resistance (<10%) to most antimicrobials tested, with few exceptions. Seafood marketed as farm-raised had lower odds of contamination with antimicrobial resistant bacteria compared to wild-caught seafood (OR: 0.4, CI: 0.2–0.7). Antimicrobial resistance genes (ARGs) were detected for various classes of medically important antimicrobials. Clinically relevant ARGs included carbapenemases (bla_IMI-2, bla_NDM-1) and extended spectrum β-lactamases (ESBLs; bla_CTX-M-55). This population-scale study of AMR in seafood sold in the United States provided the basis for NARMS seafood monitoring, which began in 2020.

Prevalence and Antimicrobial Resistance of Bacteria Isolated from Marine and Freshwater Fish in Tanzania

This study aimed to determine the prevalence and antimicrobial resistance of bacteria isolated from retail fish and shrimp in Tanzania. A total of 92 fish and 20 shrimp samples were analyzed. Fish samples consisted of 24 Nile tilapia, 24 Nile perch, and 24 red snapper. The isolates were identified by their morphological characteristics, conventional biochemical tests, and analytical profile index test kits. The antibiotic susceptibility of selected bacteria was determined by the disc diffusion method. Out of the 92 samples analyzed, 96.7% were contaminated with 7 different bacterial species. E. coli was the most prevalent bacteria (39%), followed by Klebsiella spp. (28%) and Salmonella spp. (16%). Other species isolated from this study were Staphylococcus spp. (8%), Citrobacter (4%), Shigella spp. (3%), and Pseudomonas spp. (1%). All samples were analyzed for Campylobacter spp.; however, none of the samples tested were positive for Campylobacter spp. Fish from the open-air market were contaminated by six bacterial species: E. coli (40%), Klebsiella spp. (26%), Salmonella spp. (24%), Shigella spp. (6.7%), Citrobacter spp. (6.5%), and Pseudomonas spp. (2%), while E. coli (37%), Klebsiella spp. (33%), Staphylococcus spp. (23%), and Shigella spp. (2%) were isolated in supermarket samples. According to the International Commission on Microbiological Specifications for Foods criteria, 54 (58.7%) and 38 (41.3%) samples were good and marginally acceptable, respectively. E. coli isolates were resistant to penicillin (PEN), erythromycin (ERY), gentamicin (GEN), azithromycin (AZM), and tetracycline (TET), while Salmonella spp. isolates exhibited resistance to gentamicin (CN), tetracycline (TET), penicillin (PEN), and erythromycin (ERY). These results suggest that the presence of these bacteria might cause a health risk/hazard to human beings and may cause disease to susceptible individuals, especially immune-compromised consumers.

A review of antimicrobial resistance in imported foods

Antimicrobial resistance is one of the most serious threats to medical science. Food supply is recognized as a potential source of resistant bacteria, leading to the development of surveillance programs targeting primarily poultry, pork, and beef. These programs are limited in scope, not only in the commodities tested, but also in the organisms targeted (Escherichia coli, Salmonella, and Campylobacter); consequently, neither the breadth of food products available nor the organisms that may harbour clinically relevant and (or) mobile resistance genes are identified. Furthermore, there is an inadequate understanding of how international trade in food products contributes to the global dissemination of resistance. This is despite the recognized role of international travel in disseminating antimicrobial-resistant organisms, notably New Delhi metallo-beta-lactamase. An increasing number of studies describing antimicrobial-resistant organisms in a variety of imported foods are summarized in this review.

Antimicrobial Blue Light versus Pathogenic Bacteria: Mechanism, Application in the Food Industry, Hurdle Technologies and Potential Resistance

Blue light primarily exhibits antimicrobial activity through the activation of endogenous photosensitizers, which leads to the formation of reactive oxygen species that attack components of bacterial cells. Current data show that blue light is innocuous on the skin, but may inflict photo-damage to the eyes. Laboratory measurements indicate that antimicrobial blue light has minimal effects on the sensorial and nutritional properties of foods, although future research using human panels is required to ascertain these findings. Food properties also affect the efficacy of antimicrobial blue light, with attenuation or enhancement of the bactericidal activity observed in the presence of absorptive materials (for example, proteins on meats) or photosensitizers (for example, riboflavin in milk), respectively. Blue light can also be coupled with other treatments, such as polyphenols, essential oils and organic acids. While complete resistance to blue light has not been reported, isolated evidence suggests that bacterial tolerance to blue light may occur over time, especially through gene mutations, although at a slower rate than antibiotic resistance. Future studies can aim at characterizing the amount and type of intracellular photosensitizers across bacterial species and at assessing the oxygen-independent mechanism of blue light-for example, the inactivation of spoilage bacteria in vacuum-packed meats.

The microbial safety of fish and fish products: Recent advances in understanding its significance, contamination sources, and control strategies

Microorganisms play a crucial and unique role in fish and fish product safety. The presence of human pathogens and the formation of histamine caused by spoilage bacteria make the control of both pathogenic and spoilage microorganisms critical for fish product safety. To provide a comprehensive and updated overview of the involvement of microorganisms in fish and fish product safety, this paper reviewed outbreak and recall surveillance data obtained from government agencies from 1998 to 2018 and identified major safety concerns associated with both domestic and imported fish products. The review also summarized all available literature about the prevalence of major and emerging microbial safety concerns, including Salmonella spp., Listeria monocytogenes, and Aeromonas hydrophila, in different fish and fish products and the survival of these pathogens under different storage conditions. The prevalence of antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs), two emerging food safety concerns, is also reviewed. Pathogenic and spoilage microorganisms as well as ARB and ARGs can be introduced into fish and fish products in both preharvest and postharvest stages. Many novel intervention strategies have been proposed and tested for the control of different microorganisms on fish and fish products. One key question that needs to be considered when developing and implementing novel control measures is how to ensure that the measures are cost and environment friendly as well as sustainable. Over the years, regulations have been established to provide guidance documents for good farming and processing practices. To be more prepared for the globalization of the food chain, harmonization of regulations is still needed.

Bacteriophage biocontrol to fight Listeria outbreaks in seafood

Listeria monocytogenes is a well-known pathogen responsible for the severe foodborne disease listeriosis. The control of L. monocytogenes occurrence in seafood products and seafood processing environments is an important challenge for the seafood industry and the public health sector. However, bacteriophage biocontrol shows great potential to be used as safety control measure in seafood. This review provides an update on Listeria-specific bacteriophages, focusing on their application as a safe and natural strategy to prevent L. monocytogenes contamination and growth in seafood products and seafood processing environments. Furthermore, the main properties required from bacteriophages intended to be used as biocontrol tools are summarized and emerging strategies to overcome the current limitations are considered. Also, major aspects relevant for bacteriophage production at industrial scale, their access to the market, as well as the current regulatory status of bacteriophage-based solutions for Listeria biocontrol are discussed.

High-flux simultaneous screening of common foodborne pathogens and their virulent factors

Rapid and sensitive detection techniques for foodborne pathogens are important to the food industry. However, traditional detection methods rely on bacterial culture in combination with biochemical tests, a process that typically takes 4-7 days to complete. In this study, we described a high-flux polymerase chain reaction (PCR) method for simultaneous detection of nine targeted genes (rfbE, stx1, stx2, invA, oprI, tlh, trh, tdh, and hlyA) with multiplex strains. The designed primers were highly specific for their respective target gene fragments. As the selected primers follow the principles of similar melting and annealing temperature, all the targeted genes could be detected for one strain with the same PCR program. Combining with 96-well PCR plate, by adding a single different gene to each well in each row, both the ATCC strains (E. coli, Salmonella spp., V. parahaemolyticus, L. monocytogenes, P. aeruginosa, S. aureus) and the clinical strains (E. coli, P. aeruginosa, S. aureus) were simultaneously detected to carry their specific and virulence genes. Therefore, using 96-well PCR plate for PCR amplification might be applied to high-flux sequencing of specific and virulence genes.

The use of the so-called 'tubs' for transporting and storing fresh fishery products

On-land transport/storage of fresh fishery products (FFP) for up to 3 days in 'tubs' of three-layered poly-ethylene filled with freshwater and ice was compared to the currently authorised practice (fish boxes of high-density poly-ethylene filled with ice). The impact on the survival and growth of biological hazards in fish and the histamine production in fish species associated with a high amount of histidine was assessed. In different modelling scenarios, the FFP are stored on-board in freshwater or seawater/ice (in tubs) and once on-land they are 'handled' (i.e. sorted or gutted and/or filleted) and transferred to either tubs or boxes. The temperature of the FFP was assumed to be the most influential factor affecting relevant hazards. Under reasonably foreseeable 'abusive' scenarios and using a conservative modelling approach, the growth of the relevant hazards (i.e. Listeria monocytogenes, Aeromonas spp. and non-proteolytic Clostridium botulinum), is expected to be < 0.2 log10 units higher in tubs than in boxes after 3 days when the initial temperature of the fish is 0°C ('keeping' process). Starting at 7°C ('cooling-keeping' process), the expected difference in the growth potential is higher (< 1 log10 for A. hydrophila and < 0.5 log10 for the other two hazards) due to the poorer cooling capacity of water and ice (tub) compared with ice (box). The survival of relevant hazards is not or is negligibly impacted. Histamine formation due to growth of Morganella psychrotolerans under the 'keeping' or 'cooling-keeping' process can be up to 0.4 ppm and 1.5 ppm higher, respectively, in tubs as compared to boxes after 3 days, without reaching the legal limit of 100 ppm. The water uptake associated with the storage of the FFP in tubs (which may be up to 6%) does not make a relevant contribution to the differences in microbial growth potential compared to boxes.

Antibiotic-Resistant Salmonella in the Food Supply and the Potential Role of Antibiotic Alternatives for Control

Salmonella enterica is one of the most ubiquitous enteropathogenic bacterial species on earth, and comprises more than 2500 serovars. Widely known for causing non-typhoidal foodborne infections (95%), and enteric (typhoid) fever in humans, Salmonella colonizes almost all warm- and cold-blooded animals, in addition to its extra-animal environmental strongholds. The last few decades have witnessed the emergence of highly virulent and antibiotic-resistant Salmonella, causing greater morbidity and mortality in humans. The emergence of several Salmonella serotypes resistant to multiple antibiotics in food animals underscores a significant food safety hazard. In this review, we discuss the various antibiotic-resistant Salmonella serotypes in food animals and the food supply, factors that contributed to their emergence, their antibiotic resistance mechanisms, the public health implications of their spread through the food supply, and the potential antibiotic alternatives for controlling them.

Development of an Electrochemical DNA Biosensor to Detect a Foodborne Pathogen

Vibrio parahaemolyticus (V. parahaemolyticus) is a common foodborne pathogen that contributes to a large proportion of public health problems globally, significantly affecting the rate of human mortality and morbidity. Conventional methods for the detection of V. parahaemolyticus such as culture-based methods, immunological assays, and molecular-based methods require complicated sample handling and are time-consuming, tedious, and costly. Recently, biosensors have proven to be a promising and comprehensive detection method with the advantages of fast detection, cost-effectiveness, and practicality. This research focuses on developing a rapid method of detecting V. parahaemolyticus with high selectivity and sensitivity using the principles of DNA hybridization. In the work, characterization of synthesized polylactic acid-stabilized gold nanoparticles (PLA-AuNPs) was achieved using X-ray Diffraction (XRD), Ultraviolet-visible Spectroscopy (UV-Vis), Transmission Electron Microscopy (TEM), Field-emission Scanning Electron Microscopy (FESEM), and Cyclic Voltammetry (CV). We also carried out further testing of stability, sensitivity, and reproducibility of the PLA-AuNPs. We found that the PLA-AuNPs formed a sound structure of stabilized nanoparticles in aqueous solution. We also observed that the sensitivity improved as a result of the smaller charge transfer resistance (Rct) value and an increase of active surface area (0.41 cm²). The development of our DNA biosensor was based on modification of a screen-printed carbon electrode (SPCE) with PLA-AuNPs and using methylene blue (MB) as the redox indicator. We assessed the immobilization and hybridization events by differential pulse voltammetry (DPV). We found that complementary, non-complementary, and mismatched oligonucleotides were specifically distinguished by the fabricated biosensor. It also showed reliably sensitive detection in cross-reactivity studies against various food-borne pathogens and in the identification of V. parahaemolyticus in fresh cockles.

Virulence and Antibiotic Resistance of Vibrio parahaemolyticus Isolates from Seafood from Three Developing Countries and of Worldwide Environmental, Seafood, and Clinical Isolates from 2000 to 2017

Vibrio parahaemolyticus is a leading cause of seafood-associated illness. This study investigated the prevalence, virulence, and antibiotic resistance of V. parahaemolyticus in three low- and middle-income countries. Freshly caught fish samples (n = 330) imported to Jordan from Yemen, India, and Egypt were tested. The overall prevalence of V. parahaemolyticus was 15% (95% confidence interval: 11 to 19%). Three isolates (6%) were positive for the thermostable direct hemolysin-related (trh) gene, and all isolates was negative for the thermostable direct hemolysin (tdh) gene. All isolates were resistant to colistin sulfate, neomycin, and kanamycin, and 51 and 43% of isolates were resistant to tetracycline and ampicillin, respectively. Only 4% of the isolates were resistant to cefotaxime and chloramphenicol, and no isolates were resistant to sulfamethoxazole-trimethoprim, streptomycin, gentamicin, ciprofloxacin, and nalidixic acid. All isolates were resistant to two classes of antibiotics, and 86% were multidrug resistant (resistant to at least one drug in three or more classes of antibiotics). A literature review of clinical, seafood, and environmental V. parahaemolyticus isolates worldwide revealed high rates of gentamicin and ampicillin resistance, emerging resistance to third-generation cephalosporins, and limited resistance to sulfamethoxazole-trimethoprim, ciprofloxacin, nalidixic acid, and chloramphenicol. Thus, last-resort antibiotics could be ineffective for treating V. parahaemolyticus infections. Several global reports also documented illness outbreaks in humans caused by trh- and tdh-negative V. parahaemolyticus strains. More research is needed to determine whether the presence of these genes is sufficient to classify the strains as virulent.

Seafood pathogens and information on antimicrobial resistance: A review

Seafood-borne diseases are a major public health hazard in the United States and worldwide. Per capita, seafood consumption has increased globally during recent decades. Seafood importation and domestic aquaculture farming has also increased. Moreover, several recent outbreaks of human gastroenteritis have been linked to the consumption of contaminated seafood. Investigation of seafood-borne illnesses caused by norovirus, and Vibrio, and other bacteria and viruses require a concrete knowledge about the pathogenicity and virulence properties of the etiologic agents. This review explores pathogens that have been associated with seafood and resulting outbreaks in the U.S. and other countries as well as the presence of antimicrobial resistance in the reviewed pathogens. The spectrum of such resistance is widening due to the overuse, misuse, and sub-therapeutic application of antimicrobials in humans and animals.

Antimicrobial Resistance Percentages of Salmonella and Shigella in Seafood Imported to Jordan: Higher Percentages and More Diverse Profiles in Shigella

This study determined the prevalence and antimicrobial resistance of human-specific ( Shigella spp.) and zoonotic ( Salmonella enterica ) foodborne pathogens in internationally traded seafood. Sixty-four Salmonella and 61 Shigella isolates were obtained from 330 imported fresh fish samples from Egypt, Yemen, and India. The pathogens were isolated on selective media, confirmed by PCR, and tested for antimicrobial resistance. Approximately 79 and 98% of the Salmonella and Shigella isolates, respectively, exhibited resistance to at least one antimicrobial, and 8 and 49% exhibited multidrug resistance (resistance to three or more antimicrobial classes). Generally, Salmonella exhibited high resistance to amoxicillin-clavulanic acid, cephalothin, streptomycin, and ampicillin; very low resistance to kanamycin, tetracycline, gentamicin, chloramphenicol, nalidixic acid, sulfamethoxazole-trimethoprim, and ciprofloxacin; and no resistance to ceftriaxone. Meanwhile, Shigella spp. exhibited high resistance to tetracycline, amoxicillin-clavulanic acid, cephalothin, streptomycin, and ampicillin; low resistance to kanamycin, nalidixic acid, sulfamethoxazole-trimethoprim, and ceftriaxone; and very low resistance to gentamicin and ciprofloxacin. Salmonella isolates exhibited 14 resistance profiles, Shigella isolates 42. This study is novel in showing that a human-specific pathogen has higher antimicrobial resistance percentages and more diverse profiles than a zoonotic pathogen. Thus, the impact of antimicrobial use in humans is as significant as, if not more significant than, it is in animals in spreading antibiotic resistance through food. This study also demonstrates that locally derived antimicrobial resistance can spread and pose a public health risk worldwide through seafood trade and that high resistance would make a possible outbreak difficult to control. So, capacity building and monitoring harvest water areas are encouraged in fish producing countries.

Effect of Antimicrobial Use in Agricultural Animals on Drug-resistant Foodborne Campylobacteriosis in Humans: A Systematic Literature Review

Controversy continues concerning antimicrobial use in food animals and its relationship to drug-resistant infections in humans. We systematically reviewed published literature for evidence of a relationship between antimicrobial use in agricultural animals and drug-resistant foodborne campylobacteriosis in humans. Based on publications from the United States (U.S.), Canada and Denmark from 2010 to July 2014, 195 articles were retained for abstract review, 50 met study criteria for full article review with 36 retained for which data are presented. Two publications reported increase in macrolide resistance of Campylobacter coli isolated from feces of swine receiving macrolides in feed, and one of these described similar findings for tetracyclines and fluoroquinolones. A study in growing turkeys demonstrated increased macrolide resistance associated with therapeutic dosing with Tylan® in drinking water. One publication linked tetracycline-resistant C. jejuni clone SA in raw cow's milk to a foodborne outbreak in humans. No studies that identified farm antimicrobial use also traced antimicrobial-resistant Campylobacter from farm to fork. Recent literature confirms that on farm antibiotic selection pressure can increase colonization of animals with drug-resistant Campylobacter spp. but is inadequately detailed to establish a causal relationship between use of antimicrobials in agricultural animals and prevalence of drug-resistant foodborne campylobacteriosis in humans.

Prevalence and Persistence of Listeria monocytogenes in Ready-to-Eat Tilapia Sashimi Processing Plants

A 2-year study was performed at two ready-to-eat tilapia sashimi processing plants (A and B) to identify possible routes of contamination with Listeria monocytogenes during processing. Samples were collected from the aquaculture environments, transportation tanks, processing plants, and final products. Seventy-nine L. monocytogenes isolates were found in the processing environments and final products; 3.96% (50 of 1,264 samples) and 3.86% (29 of 752 samples) of the samples from plants A and B, respectively, were positive for L. monocytogenes . No L. monocytogenes was detected in the aquaculture environments or transportation tanks. The predominant L. monocytogenes serotypes were 1/2b (55.70%) and 4b (37.97%); serotypes 3b and 4e were detected at much lower percentages. At both plants, most processing sections were contaminated with L. monocytogenes before the start of processing, which indicated that the cleaning and sanitizing methods did not achieve adequate pathogen removal. Eleven seropulsotypes were revealed by pulsed-field gel electrophoresis and serotyping. Analysis of seropulsotype distribution revealed that the contamination was disseminated by the processing work; the same seropulsotypes were repeatedly found along the work flow line and in the final products. Specific seropulsotypes were persistently found during different sampling periods, which suggests that the sanitation procedures or equipment used at these plants were inadequate. Plant staff should improve the sanitation procedures and equipment to reduce the risk of L. monocytogenes cross-contamination and ensure the safety of ready-to-eat tilapia products.

Architecture of Class 1, 2, and 3 Integrons from Gram Negative Bacteria Recovered among Fruits and Vegetables

The spread of antibiotic resistant bacteria throughout the food chain constitutes a public health concern. To understand the contribution of fresh produce in shaping antibiotic resistance bacteria and integron prevalence in the food chain, 333 antibiotic resistance Gram negative isolates were collected from organic and conventionally produced fruits (pears, apples, and strawberries) and vegetables (lettuces, tomatoes, and carrots). Although low levels of resistance have been detected, the bacterial genera identified in the assessed fresh produce are often described not only as environmental, but mostly as commensals and opportunistic pathogens. The genomic characterization of integron-harboring isolates revealed a high number of mobile genetic elements and clinically relevant antibiotic resistance genes, of which we highlight the presence of as mcr-1, qnrA1, bla_GES−11, mphA, and oqxAB. The study of class 1 (n = 8), class 2 (n = 3) and class 3 (n = 1) integrons, harbored by species such as Morganella morganii, Escherichia coli, Klebsiella pneumoniae, led to the identification of different integron promoters (PcW, PcH1, PcS, and PcW_TNG−10) and cassette arrays (containing drfA, aadA, cmlA, estX, sat, and bla_GES). In fact, the diverse integron backbones were associated with transposable elements (e.g., Tn402, Tn7, ISCR1, Tn2^*, IS26, IS1326, and IS3) that conferred greater mobility. This is also the first appearance of In1258, In1259, and In3-13, which should be monitored to prevent their establishment as successfully dispersed mobile resistance integrons. These results underscore the growing concern about the dissemination of acquired resistance genes by mobile elements in the food chain.

Pathogenic vibrios in environmental, seafood and clinical sources in Germany

Bacteria of the family Vibrionaceae naturally occur in marine and estuarine environments. Only few species of Vibrionaceae are associated with human cases of gastroenteritis, ear and wound infections, caused by ingestion of seafood or contact with Vibrio containing water. Increasing consumption of seafood (fish, fishery products and shellfish) poses a possible source of Vibrio infections in Germany. Additionally, there is a growing concern that abundances of pathogenic vibrios may increase in German coastal waters as a result of e.g. climate change resulting in probably rising surface water temperatures. According to the One Health concept the VibrioNet consortium started in 2010 to investigate the occurrence and relevance of non-cholera vibrios of human concern in Germany. Vibrios from environmental, seafood and clinical sources were analyzed with the aim to find connections between different reservoirs or sources and to identify potential ways of transmission of these pathogens to assess the risk of infections associated with them. Potentially pathogenic strains mostly belong to the species Vibrio parahaemolyticus, Vibrio vulnificus and non-O1/non-O139 Vibrio cholerae. Investigations on imported seafood and mussels from primary production areas confirmed the frequent occurrence of these species. Moreover, studies of German coastal waters and sediments showed the presence and seasonality of these marine bacteria. So far the incidence of clinical cases of vibriosis in Germany is low. Between 1994 and 2013 thirteen cases of Vibrio spp. associated wound infections and/or septicaemia have been reported. However, the high prevalence of vibrios in aquatic environments and aquatic organisms is of concern and demands continued control of food and surveillance for clinical infections with pathogenic vibrios.

Antimicrobial Susceptibility of Escherichia coli Isolated from Fresh-Marketed Nile Tilapia (Oreochromis niloticus)

The contamination of seafood by bacteria of fecal origin, especially Escherichia coli, is a widely documented sanitary problem. The objective of the present study was to isolate E. coli strains from the gills, muscle, and body surface of farmed Nile tilapias (Oreochromis niloticus) fresh-marketed in supermarkets in Fortaleza (Ceará, Brazil), to determine their susceptibility to antibiotics of different families (amikacin, gentamicin, imipenem, cephalothin, cefotaxime, ciprofloxacin, aztreonam, ampicillin, nalidixic acid, tetracycline, and sulfametoxazol-trimetoprim), and to determine the nature of resistance by plasmid curing. Forty-four strains (body surface = 25, gills = 15, muscle = 4) were isolated, all of which were susceptible to amikacin, aztreonam, cefotaxime, ciprofloxacin, gentamicin, and imipenem. Gill and body surface samples yielded 11 isolates resistant to ampicillin, tetracycline, and sulfametoxazol-trimetoprim, 4 of which of plasmidial nature. The multiple antibiotic resistance index was higher for strains isolated from body surface than from gills. The overall high antibiotic susceptibility of E. coli strains isolated from fresh-marketed tilapia was satisfactory, although the occasional finding of plasmidial resistance points to the need for close microbiological surveillance of the farming, handling, and marketing conditions of aquaculture products.

Inhibitory effects of chitosan coating combined with organic acids on Listeria monocytogenes in refrigerated ready-to-eat shrimps

Chitosan and organic acids are natural preservatives with proven antimicrobial efficacies. This study investigated the effects of chitosan coating combined with organic acids on inhibiting Listeria monocytogenes in ready-to-eat (RTE) shrimps during storage at 4°C. Cooked shrimps inoculated with L. monocytogenes were coated with 0.5 and 1 % chitosan solutions in combination with 2 % organic acids (acetic, citric, lactic, and malic acids) for 5 min and then stored at 4°C for 16 days. Bacterial counts, pH, and sensory properties were analyzed every 4 days. The results indicated that the antimicrobial effects of chitosan were significantly enhanced (P < 0.05) when it was combined with 2 % acetic, citric, lactic, or malic acid. Chitosan at 1 % combined with 2 % acetic acid was the most effective treatment, which caused a 5.38-log CFU/g bacterial reduction after 16 days in comparison with the controls. Transmission electron microscopy further confirmed the enhanced antimicrobial effects of the combination of chitosan and organic acids. Such combined treatments also maintained the sensory properties of RTE shrimps. The use of chitosan coating combined with organic acids significantly lowered (P < 0.05) the pH values of RTE shrimps compared with the use of chitosan alone. Therefore, we conclude that chitosan coating combined with acetic acid could be a promising antimicrobial method to prevent the proliferation of L. monocytogenes in RTE shrimps with extended shelf life.

Prevalence, serovars, and antimicrobial susceptibility of Salmonella isolated from blue land crabs (Cardisoma guanhumi) in Grenada, West Indies

Samples of intestine and hepatopancreas from 65 blue land crabs (Cardisoma guanhumi), a crustacean commonly consumed as a food item in Grenada, were collected from six geographic sites in Grenada and tested for Salmonella by enrichment and selective culture. The individual animal prevalence of Salmonella based on isolation was 17% (11 of 65), and all infected crabs were from three of the six sampled locations. Isolates were identified by serotyping as Salmonella enterica serovars Saintpaul (n = 6), Montevideo (n = 4), and Newport (n = 1). The intestines of all 11 infected crabs were positive for Salmonella, but only 7 of 11 hepatopancreas samples were positive for Salmonella, and these isolates were the same serovar as isolated from the matching intestine. These three Salmonella serovars are known to cause human illness in many countries, and in the Caribbean Salmonella Saintpaul has been frequently isolated from humans. In a disc diffusion assay, all isolates were susceptible to all 11 drugs tested: amoxicillin-clavulanic acid, ampicillin, cephalothin, chloramphenicol, ciprofloxacin, gentamicin, imipenem, neomycin, streptomycin, tetracycline, and trimethoprim-sulfamethoxazole. To our knowledge, this report is the first concerning isolation and antimicrobial susceptibilities of Salmonella serotypes from the blue land crab.