Effect of the food production chain from farm practices to vegetable processing on outbreak incidence

Microbial Food Safety Aspects Along the Supply Chain of African Indigenous Vegetables. A Case Study of Leaf Amaranth (Amaranthus spp.) in Kenya

Microbial food safety aspects along the supply chain of fresh leaf amaranth (Amaranthus spp.) were evaluated from farms to urban supermarkets in Kenya. A total of 150 leaf samples were collected from amaranth farms, transport, wholesale, peri-urban retail markets, and supermarkets. Microbiological indicators of sanitary conditions were analyzed in terms of the prevalence and load of aerobic mesophilic bacteria, Enterobacteriaceae, total coliforms, yeasts & molds, Escherichia coli, Salmonella, and Staphylococcus aureus. Foodborne pathogens, E. coli, Salmonella, and S. aureus, were characterized through molecular screening for selected virulence genes. The prevalence of microbial contamination was highest in peri-urban retail markets, followed by wholesale markets, supermarkets, and transportation, and least on farms. Throughout the supply chain, coliforms were the most prevalent, detected in 98.7% of the samples, followed by Enterobacteriaceae (97.3%), aerobic mesophiles (96.7%), and yeasts and molds (92%). However, S. aureus was the most prevalent pathogen (87.3%), followed by Salmonella (79.3%) and E. coli the least (67.3%). Microbial load increased from the farm to peri-urban retail markets and was significantly higher in the peri-urban retail markets, i.e., 5.08-6.22 Log CFU/g (aerobic mesophiles), 5.28-6.32 Log CFU/g (Enterobacteriaceae), 5.56-6.47 Log CFU/g (coliforms), 2.02-3.59 Log CFU/g (E. coli), 3.87-4.64 Log CFU/g (S. aureus), and 3.36-4.23 Log CFU/g (Salmonella), respectively. Shiga toxin-producing E. coli virulence genes (stx1 and stx2), enterotoxin (stn), and plasmid (pCT) Salmonella virulence genes, and S. aureus virulence genes (sea) were detected in isolates from vegetables at different nodes of the supply chain. Microbial contamination levels were above the international and national thresholds, and foodborne microorganisms had pathogenic attributes. Initiatives to improve sanitation measures at each stage of the supply chain are recommended to guarantee food safety.

Effect of surface roughness on the efficacy of Plasma Activated Mist (PAM) for inactivation of Listeria innocua and Klebsiella michiganensis

Cold plasma generated by dielectric barrier discharge (DBD) and DBD combined with nebulized liquid microdroplets to generate plasma-activated mist (PAM) have shown the potential as a surface decontamination method for the food industry. The objective of this research was to measure the microbial inactivation caused by DBD and by PAM on tryptic soy agar (TSA) and on glass slides and to determine the efficacy of PAM on selected surfaces having different surface topographies. Tryptic soy agar in Petri dishes and on glass slides (surface roughness Pq = 0.28 ± 0.02 μm) was inoculated with either 0.1 mL of inoculum containing Listeria innocua (8.4 ± 0.1 log CFU/mL) or Klebsiella michiganensis (8.8 ± 0.2 log CFU/mL) and exposed to either DBD or PAM for 5 to 20 min. Glass slides, grape tomatoes (Pq = 5.17 μm ± 0.53 μm), limes (Pq = 18.76 μm ± 3.00 μm), and spiny gourds (Pq = 101.50 μm ± 10.95 μm) were also surface-inoculated with L. innocua or K. michiganensis and exposed to PAM for 5 to 20 min. No significant difference in microbial inactivation was observed between DBD plasma and PAM for all treatment times. The smoothest surface (glass) showed the highest reduction in L. innocua (3.4 ± 0.2 log CFU/item) and K. michiganensis (5.7 ± 0.0 log CFU/item) after PAM treatment. The roughest surface (spiny gourd) yielded a significantly lower reduction for L. innocua (1.0 ± 0.2 log CFU/item) and K. michiganensis (1.8 ± 0.1 log CFU/item). L. innocua was less susceptible to inactivation by PAM compared K. michiganensis. This study highlighted the importance of surface roughness on microbial inactivation of L. innocua and K. michiganensis by DBD and PAM on produce surfaces.

Presence of Clostridioides difficile on spinach, carrots, cheese and milk in Turkey

INTRODUCTION

The presence of Clostridioides difficile in water, soil, fertilizers, and animal feces suggests the potential existence of C. difficile in foods that come into contact with these sources or become contaminated through indirect means.

MATERIAL & METHOD

A total of 431 samples, consisting of spinach and carrots and raw milk and cheese obtained from cows, goats, buffalo, and sheep, were examined for the presence of C. difficile. Isolates were identified by real-time PCR, ribotyped, and their toxin profiles were determined. Antibiotic susceptibility to vancomycin, clindamycin, and metronidazole was evaluated using the E-test.

RESULTS

C. difficile was detected in 3.27 % (4/122) of spinach, 1.85 % (2/108) of carrots, and 2.19 % (2/91) of milk samples. No C. difficile was detected in the cheeses (n = 110). All isolates were obtained from different fields/farms. Only one isolate (from spinach) carried the tcdA and tcdB toxin genes. Six different PCR ribotypes were detected, with two (001, 060) being identified. All isolates were sensitive to vancomycin, clindamycin, and metronidazole.

CONCLUSION

The prevalence of C. difficile in spinach, carrot, and milk samples from selected regions was low, and nontoxigenic strains were prevalent. Despite the low prevalence, the detection of C. difficile in these foods highlights the potential risk of foodborne transmission of this pathogen and underscores the need for monitoring and control strategies to ensure food safety.

Prevalence and Genomic Investigation of Salmonella Isolates Associated with Watermelons and Their Environmental Reservoirs in Bejaia, Algeria

This study was conducted in Bejaia, Algeria, to determine the presence of Salmonella in fresh watermelon (n = 105), soil (n = 23), and irrigation water samples (n = 17) collected from two different farms. After isolation, antimicrobial susceptibility testing, serotype determination, multilocus sequence typing, antimicrobial resistance genes detection, and whole genome sequencing were performed. Twenty watermelon samples (19%) were contaminated with Salmonella, but none were found in the soil or irrigation water. Among the 20 Salmonella isolates, 2 serovars were identified (Salmonella Liverpool and Salmonella Anatum), belonging to sequence types ST1959 and ST64, respectively. Ten Salmonella isolates showed significant resistance to nalidixic acid, ofloxacin, and ciprofloxacin but were susceptible to all other antibiotics. The coexistence of point mutations (parC:p.T57S) in Quinolone Resistance-Determining Regions and the qnrB19 gene may contribute to quinolone resistance. The study identified 164 virulence genes in the Salmonella isolates. Our study found Salmonella in fresh watermelon during the preharvest season in Bejaia, Algeria. Our study indicates a relatively high prevalence of Salmonella on watermelon samples before harvest. Although we cannot directly compare our results with previous studies, it is crucial to recognize that the absence of comprehensive comparative data underscores the need for further research and surveillance.

Antibiotic resistance plasmids in Enterobacteriaceae isolated from fresh produce in northern Germany

In this study, the genomes of 22 Enterobacteriaceae isolates from fresh produce and herbs obtained from retail markets in northern Germany were completely sequenced with MiSeq short-read and MinION long-read sequencing and assembled using a Unicycler hybrid assembly. The data showed that 17 of the strains harbored between one and five plasmids, whereas in five strains, only the circular chromosomal DNA was detected. In total, 38 plasmids were identified. The size of the plasmids detected varied between ca. 2,000 and 326,000 bp, and heavy metal resistance genes were found on seven (18.4%) of the plasmids. Eleven plasmids (28.9%) showed the presence of antibiotic resistance genes. Among large plasmids (>32,000 bp), IncF plasmids (specifically, IncFIB and IncFII) were the most abundant replicon types, while all small plasmids were Col-replicons. Six plasmids harbored unit and composite transposons carrying antibiotic resistance genes, with IS26 identified as the primary insertion sequence. Class 1 integrons carrying antibiotic resistance genes were also detected on chromosomes of two Citrobacter isolates and on four plasmids. Mob-suite analysis revealed that 36.8% of plasmids in this study were found to be conjugative, while 28.9% were identified as mobilizable. Overall, our study showed that Enterobacteriaceae from fresh produce possess antibiotic resistance genes on both chromosome and plasmid, some of which are considered to be transferable. This indicates the potential for Enterobacteriaceae from fresh produce that is usually eaten in the raw state to contribute to the transfer of resistance genes to bacteria of the human gastrointestinal system.

IMPORTANCE

This study showed that Enterobacteriaceae from raw vegetables carried plasmids ranging in size from 2,715 to 326,286 bp, of which about less than one-third carried antibiotic resistance genes encoding resistance toward antibiotics such as tetracyclines, aminoglycosides, fosfomycins, sulfonamides, quinolones, and β-lactam antibiotics. Some strains encoded multiple resistances, and some encoded extended-spectrum β-lactamases. The study highlights the potential of produce, which may be eaten raw, as a potential vehicle for the transfer of antibiotic-resistant bacteria.

Prevention of foodborne viruses and pathogens in fresh produce and root vegetables

Every year, 1 in 10 people suffers from food poisoning, and in recent years, the highest number of foodborne outbreaks has been attributed to roots/underground vegetables and fresh produce. Major pathogens include as Escherichia coli, Salmonella enterica, Listeria monocytogenes, Human Norovirus, Hepatitis A virus and Cyclospora. The primary sources of contamination for agriculture products stem from uncontrolled exposure to soil, water, and animal waste. Contamination can occur in various ways during food cultivation, harvesting, processing, and distribution. Mechanical washing and disinfection are primarily employed as practices to control biological contaminants such as bacteria, viruses, and parasites. Current practices may encounter challenges such as microbial resistance to disinfectants or antibiotics, and the cleaning effectiveness could be compromised due to the internalization of bacteria and viruses into some plants. High-pressure processing, pulse electric fields, and cold plasma are environmentally friendly technologies, albeit with associated costs. Low-temperature sterilization technologies capable of controlling biological contaminants, such as bacteria and viruses, play a crucial role in preventing food safety issues. Compared to conventional cleaning methods, these technologies are effective in controlling microorganisms that are strongly attached to the food surface or internalized due to damage. Periodic surveillance is essential to ensure the overall microbiological safety of fresh produce and root vegetables.

Isolation, characterization, and application of a lytic bacteriophage SSP49 to control Staphylococcus aureus contamination on baby spinach leaves

Staphylococcus aureus, a major foodborne pathogen, is frequently detected in fresh produce. It often causes food poisoning accompanied by abdominal pain, diarrhea, and vomiting. Additionally, the abuse of antibiotics to control S. aureus has resulted in the emergence of antibiotics-resistant bacteria, such as methicillin resistant S. aureus. Therefore, bacteriophage, a natural antimicrobial agent, has been suggested as an alternative to antibiotics. In this study, a lytic phage SSP49 that specifically infects S. aureus was isolated from a sewage sample, and its morphological, biological, and genetic characteristics were determined. We found that phage SSP49 belongs to the Straboviridae family (Caudoviricetes class) and maintained host growth inhibition for 30 h in vitro. In addition, it showed high host specificity and a broad host range against various S. aureus strains. Receptor analysis revealed that phage SSP49 utilized cell wall teichoic acid as a host receptor. Whole genome sequencing revealed that the genome size of SSP49 was 137,283 bp and it contained 191 open reading frames. The genome of phage SSP49 did not contain genes related to lysogen formation, bacterial toxicity, and antibiotic resistance, suggesting its safety in food application. The activity of phage SSP49 was considerably stable under various high temperature and pH conditions. Furthermore, phage SSP49 effectively inhibited S. aureus growth on baby spinach leaves both at 4 °C and 25 °C while maintaining the numbers of active phage during treatments (reductions of 1.2 and 2.1 log CFU/cm2, respectively). Thus, this study demonstrated the potential of phage SSP49 as an alternative natural biocontrol agent against S. aureus contamination in fresh produce.

Prevalence and antimicrobial susceptibility profile of Salmonella isolated from vegetable farms fertilized with animal manure in Addis Ababa Ethiopia

The resistance of foodborne pathogens to antimicrobial agents is a potential danger to human health. Hence, establishing the status of good agricultural practices (GAPs) and the antimicrobial susceptibility of major foodborne pathogens has a significant programmatic implication in planning interventions. The objective of this study was to assess the gap in attaining GAP and estimate the prevalence and antimicrobial susceptibility profile of Salmonella in vegetable farms fertilized with animal manure in Addis Ababa, Ethiopia. A total of 81 vegetable farms from four sub-cities in Addis Ababa were visited, and 1119 samples were collected: soil (n = 271), manure (n = 375), vegetables (n = 398), and dairy cattle feces (n = 75). Additional data were collected using a structured questionnaire. Isolation of Salmonella was done using standard microbiology techniques and antimicrobial susceptibility testing was conducted using disk diffusion assays. Carriage for antimicrobial resistance genes was tested using polymerase chain reaction (PCR). Among the 81 vegetable farms visited, 24.7% used animal manure without any treatment, 27.2% used properly stored animal manure and 80.2% were easily accessible to animals. The prevalence of Salmonella was 2.3% at the sample level, 17.3% at the vegetable farm level, and 2.5% in vegetables. The highest rate of resistance was recorded for streptomycin, 80.7% (21 of 26), followed by kanamycin, 65.4% (17 of 26), and gentamicin, 61.5% (16 of 26). Multidrug resistance was detected in 61.5% of the Salmonella isolates. Vegetable farms have a gap in attaining GAPs, which could contribute to increased contamination and the transfer of antimicrobial resistance to the vegetables. The application of GAPs, including proper preparation of compost and the appropriate use of antimicrobials in veterinary practices, are recommended to reduce the emergence and spread of antimicrobial resistance.

Ultra violet-C pretreatment enhances the antimicrobial efficacy of unpeeled carrots against subsequent contamination with Listeria monocytogenes

To our knowledge, this study is the first to elucidate the bactericidal efficacy of unpeeled carrots (hereafter referred to as carrots) pretreated with Ultra Violet-C (UV-C) against subsequent contamination with Listeria monocytogenes. Carrots pretreated with UV-C (240 mJ/cm2) exhibited a significant antilisterial effect within 2 h. In fact, the population of UV-C-pretreated carrots decreased from 7.94 log CFU/cm2 to levels below the limit of detection (LOD; <1.65 log CFU/cm2) within 24 h. For carrots that were not pretreated with UV-C, 3-4 log reductions were found after 24 h. Carrots pretreated with UV-C exhibited antimicrobial activity against another gram-positive pathogen, Staphylococcus aureus, but not against the gram-negative pathogens, E. coli O157:H7 and Salmonella enterica. Pretreatment with UV-C created a lasting antimicrobial effect as introducing L. monocytogenes on carrots, 72 h post-UV-C treatment, still maintained the antilisterial effect. Notably, all UV-C doses in the range of 48-240 mJ/cm2 induced a lasting antilisterial effect. The bactericidal effects against L. monocytogenes were confirmed in three varieties of washed and unwashed carrots (Danvers, Nantes, and Chantenay). Fluorescence microscopy confirmed the bactericidal effect of UV-C-pretreated carrots on the survival of L. monocytogenes. Conclusively, pretreating carrots with UV-C can reduce the population of L. monocytogenes to levels below the LOD and may further prevent pathogen growth during cold storage. Additional studies are necessary to discern the mechanism underlying the bactericidal efficacy of UV-C-pretreated carrots.

Presence of Cryptosporidium parvum in pre-washed vegetables from different supermarkets in South East England: A pilot study

Cryptosporidium is an important water-borne and food-borne parasite with a high burden of disease. This organism has been shown to contaminate various leafy vegetables; however, studies assessing the presence of Cryptosporidium spp in pre-washed and ready-to-eat vegetables are limited. Routine surveillance in the UK revealed a nationwide exceedance of human cases of Cryptosporidium. Therefore, this study aims to assess the presence of this parasite in pre-washed vegetables from supermarkets in the UK. A total of 36 samples were purchased from four different supermarkets. A nested PCR targeting the SSU rRNA was carried out on 24 samples, 58% were PCR-positive for Cryptosporidium. Sanger sequencing confirmed that, of these sequences, 4/24 (17%) produced significant similarities to Cryptosporidium parvum. This study provides evidence for the presence of C. parvum in pre-washed and ready-to-eat vegetables. Future work to identify the point of contamination is required.

Improving the Detection and Understanding of Infectious Human Norovirus in Food and Water Matrices: A Review of Methods and Emerging Models

Human norovirus (HuNoV) is a leading global cause of viral gastroenteritis, contributing to numerous outbreaks and illnesses annually. However, conventional cell culture systems cannot support the cultivation of infectious HuNoV, making its detection and study in food and water matrices particularly challenging. Recent advancements in HuNoV research, including the emergence of models such as human intestinal enteroids (HIEs) and zebrafish larvae/embryo, have significantly enhanced our understanding of HuNoV pathogenesis. This review provides an overview of current methods employed for HuNoV detection in food and water, along with their associated limitations. Furthermore, it explores the potential applications of the HIE and zebrafish larvae/embryo models in detecting infectious HuNoV within food and water matrices. Finally, this review also highlights the need for further optimization and exploration of these models and detection methods to improve our understanding of HuNoV and its presence in different matrices, ultimately contributing to improved intervention strategies and public health outcomes.

Total coliforms, microbial diversity and multiple characteristics of Salmonella in soil-irrigation water-fresh vegetable system in Shaanxi, China

Global occurrences of foodborne disease outbreaks have been documented, involving fresh agricultural produce contaminated by various pathogens. This contamination can occur at any point in the supply chain. However, studies on the prevalence of total coliforms, Salmonella and microbial diversity in vegetable and associated environments are limited. This study aimed to assess 1) the number of total coliforms (n = 299) and diversity of microbial communities (n = 52); 2) the prevalence, antibiotic susceptibility, genomic characteristics, and potential transmission relationships of Salmonella in soil-irrigation water-vegetable system (n = 506). Overall, 84.28 % samples were positive to total coliforms, with most frequently detected in soil (100 %), followed by irrigation water (79.26 %) and vegetables (62.00 %). A seasonal trend in coliform prevalence was observed, with significantly higher levels in summer (P < 0.05). Detection rates of Salmonella in soil, vegetable and irrigation water were 2.21 %, 4.74 % and 9.40 %. Fourteen serotypes and sequence types (STs) were respectively annotated in 56 Salmonella isolates, ST13 S. Agona (30.36 %, 17/56), ST469 S. Rissen (25.00 %, 14/56), and ST36 S. Typhimurium (12.50 %, 7/56) were dominant serotypes and STs. Thirty-one (55.36 %) isolates were multi-drug resistant, and the resistance was most frequently found to ampicillin (55.36 %, 31/56), followed by to sulfamethoxazole (51.79 %, 29/56) and tetracycline (50.00 %, 28/56). The genomic characteristics and antibiotic resistance patterns of Salmonella isolates from soil, vegetables, and irrigation water within a coherent geographical locale exhibited remarkable similarities, indicating Salmonella may be transmitted among these environments or have a common source of contamination. Microbial alpha diversity indices in soil were significantly higher (P < 0.05) than that in vegetable and irrigation water. The microbial phylum in irrigation water covered that in the vegetable, demonstrating a significant overlap in the microbial communities between the vegetables and the irrigation water.

Biocontrol of Escherichia coli O157:H7 by Enterobacter asburiae AEB30 on intact cantaloupe melons

Escherichia coli O157:H7 causes >73,000 foodborne illnesses in the United States annually, many of which have been associated with fresh ready-to-eat produce including cantaloupe melons. In this study, we created a produce-associated bacterial (PAB) library containing >7500 isolates and screened them for the ability to inhibit the growth of E. coli O157:H7 using an in vitro fluorescence-based growth assay. One isolate, identified by 16S and whole-genome sequence analysis as Enterobacter asburiae, was able to inhibit the growth of E. coli by ~30-fold in vitro and produced zones of inhibition between 13 and 21 mm against 12 E. coli outbreak strains in an agar spot assay. We demonstrated that E. asburiae AEB30 was able to grow, persist and inhibit the growth of E. coli on cantaloupe melons under simulated pre- and post-harvest conditions. Analysis of the E. asburiae AEB30 genome revealed an operon encoding a contact-dependent growth inhibition (CDI) system that when mutated resulted in the loss of E. coli growth inhibition. These data suggest that E. asburiae AEB30 is a potential biocontrol agent to prevent E. coli contamination of cantaloupe melons in both pre- and post-harvest environments and that its mode of action is via a CDI system.

Persistence of microbiological hazards in food and feed production and processing environments

Listeria monocytogenes (in the meat, fish and seafood, dairy and fruit and vegetable sectors), Salmonella enterica (in the feed, meat, egg and low moisture food sectors) and Cronobacter sakazakii (in the low moisture food sector) were identified as the bacterial food safety hazards most relevant to public health that are associated with persistence in the food and feed processing environment (FFPE). There is a wide range of subtypes of these hazards involved in persistence in the FFPE. While some specific subtypes are more commonly reported as persistent, it is currently not possible to identify universal markers (i.e. genetic determinants) for this trait. Common risk factors for persistence in the FFPE are inadequate zoning and hygiene barriers; lack of hygienic design of equipment and machines; and inadequate cleaning and disinfection. A well-designed environmental sampling and testing programme is the most effective strategy to identify contamination sources and detect potentially persistent hazards. The establishment of hygienic barriers and measures within the food safety management system, during implementation of hazard analysis and critical control points, is key to prevent and/or control bacterial persistence in the FFPE. Once persistence is suspected in a plant, a 'seek-and-destroy' approach is frequently recommended, including intensified monitoring, the introduction of control measures and the continuation of the intensified monitoring. Successful actions triggered by persistence of L. monocytogenes are described, as well as interventions with direct bactericidal activity. These interventions could be efficient if properly validated, correctly applied and verified under industrial conditions. Perspectives are provided for performing a risk assessment for relevant combinations of hazard and food sector to assess the relative public health risk that can be associated with persistence, based on bottom-up and top-down approaches. Knowledge gaps related to bacterial food safety hazards associated with persistence in the FFPE and priorities for future research are provided.

Disinfection efficiency of chlorine dioxide and peracetic acid against MNV-1 and HAV in simulated soil-rich wash water

Wash water from fresh vegetables and root vegetables is an important vehicle for foodborne virus transmission. However, there is lack of assessing rapid viral inactivation strategies in wash water characterized by a high soil content at the post-harvest stage. Considering the significance of food safety during the washing stage for fresh and root vegetable produce prior to marketing, we assessed the inactivation efficacy by using chlorine dioxide (ClO2) and peracetic acid (PAA) against a surrogate of human norovirus (murine norovirus 1, MNV-1) and hepatitis A virus (HAV), in wash water containing black soil and clay loam. The results indicated that MNV-1 and HAV were reduced to the process limit of detection (PLOD), with reductions ranging from 4.89 to 6.35 log10 PFU, and 4.63 to 4.96 log10 PFU when treated with ClO2 at 2.5 ppm for 10 mins. Comparatively, when treated with 500 ppm of PAA for 10 mins, MNV-1 and HAV were maximum reduced to 1.75 ± 0.23 log10 PFU (4.50 log10 PFU reduction) and 2.13 ± 0.12 log10 PFU (2.72 log10 PFU reduction). This demonstrated the efficacy of ClO2 in eliminating foodborne viruses in soil-rich wash water. When we validated the recovery of the virus from two types of wash water, the pH (9.24 ± 0.33 and 5.95 ± 0.05) had no impact on the recovery of MNV-1, while the recovery of HAV was less than 1 %. By adjusting the pH to a neutral level, recovery of HAV and its RNA levels was increased to 15.94 and 3.89 %. Thus, this study emphasized the critical role of pH in the recovery of HAV from the complex soil-rich aqueous environment, and the efficacy of ClO2 serving as a pivotal reference for the development of control strategies against foodborne viruses in the supply chain of fresh and root vegetables.

One Health Perspectives on Food Safety in Minimally Processed Vegetables and Fruits: From Farm to Fork

While food markets and food production chains are experiencing exponential growth, global attention to food safety is steadily increasing. This is particularly crucial for ready-to-eat products such as fresh-cut salads and fruits, as these items are consumed raw without prior heat treatment, making the presence of pathogenic microorganisms quite frequent. Moreover, many studies on foodborne illnesses associated with these foods often overlook the transmission links from the initial contamination source. The prevention and control of the dissemination of foodborne pathogens should be approached holistically, involving agricultural production, processing, transport, food production, and extending to final consumption, all while adopting a One Health perspective. In this context, our objective is to compile available information on the challenges related to microbiological contamination in minimally handled fruits and vegetables. This includes major reported outbreaks, specific bacterial strains, and associated statistics throughout the production chain. We address the sources of contamination at each stage, along with issues related to food manipulation and disinfection. Additionally, we provide potential solutions to promote a healthier approach to fresh-cut fruits and vegetables. This information will be valuable for both researchers and food producers, particularly those focused on ensuring food safety and quality.

Emergence of colistin-resistant Enterobacter cloacae and Raoultella ornithinolytica carrying the phosphoethanolamine transferase gene, mcr-9, derived from vegetables in Japan

IMPORTANCE

Plasmid-mediated mobile colistin-resistance genes have been recognized as a global threat because they jeopardize the efficacy of colistin in therapeutic practice. Here, we described the genetic features of two mcr-9.1-carrying Gram-negative bacteria with a colistin-resistant phenotype derived from vegetables in Japan. The colistin-resistant mcr-9.1, which has never been detected in vegetables, was located on a large plasmid in Enterobacter cloacae CST17-2 and Raoultella ornithinolytica CST129-1, suggesting a high chance of horizontal gene transfer. To the best of our knowledge, this is the first report of mcr-9 in R. ornithinolytica. This study indicates that fresh vegetables might be a potential source for the transmission of mcr-9 genes encoding resistance to frontline (colistin) and clinically relevant antimicrobials. The study also provides additional consideration for colistin use and the relevance of routine surveillance in epidemiological perspective to curb the continuous spread of mcr alleles.

Absence of Shiga toxin-producing Escherichia coli (STEC) in organic leafy greens from the metropolitan region of São Paulo, Brazil

Shiga toxin-producing Escherichia coli (STEC) is an important pathogen with public health implications, including its potential association with vegetables. In this study, we investigated the presence of STEC in vegetables obtained from organic producers located in São Paulo city, Brazil. As part of a routine surveillance study conducted over (years of isolation), a total of 200 samples of organic vegetables were screened using biochemical and PCR methods. Among the vegetable samples tested, 30 (15%) were positive for non-Shiga toxin-producing E. coli. While no STEC was detected in the organic vegetables in this study, the presence of non-STEC in vegetables raises concerns about the lack of proper hygiene practices during vegetable handling. This contamination represents a public health risk, particularly considering that these isolates can still be pathogenic, and vegetables are often consumed raw. To address this important issue, continuous monitoring of these farms is recommended to ensure the quality and safety of organic vegetables produced for both domestic consumption and exportation.

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.

Farm to table: colistin resistance hitchhiking through food

Colistin is a high priority, last-resort antibiotic recklessly used in livestock and poultry farms. It is used as an antibiotic for treating multi-drug resistant Gram-negative bacterial infections as well as a growth promoter in poultry and animal farms. The sub-therapeutic doses of colistin exert a selection pressure on bacteria leading to the emergence of colistin resistance in the environment. Colistin resistance gene, mcr are mostly plasmid-mediated, amplifying the horizontal gene transfer. Food products such as chicken, meat, pork etc. disseminate colistin resistance to humans through zoonotic transfer. The antimicrobial residues used in livestock and poultry often leaches to soil and water through faeces. This review highlights the recent status of colistin use in food-producing animals, its association with colistin resistance adversely affecting public health. The underlying mechanism of colistin resistance has been explored. The prohibition of over-the-counter colistin sales and as growth promoters for animals and broilers has exhibited effective stewardship of colistin resistance in several countries.

Microgreen Variety Impacts Leaf Surface Persistence of a Human Norovirus Surrogate

Human norovirus (HuNoV) is a pathogenic agent that is frequently associated with foodborne disease outbreaks linked to fresh produce. Within microgreen production systems, understanding of virus transmission routes and persistence is limited. To investigate virus persistence on microgreen leaf surfaces, this study mimicked virus contaminations caused during microgreen handling by farm workers or during overhead irrigation with contaminated water. Specifically, approximately 5 log PFU of Tulane virus (TV)-a HuNoV surrogate-was inoculated on sunflower (SF) and pea shoot (PS) microgreen leaves at 7-day age. The virus reduction on SF was significantly higher than PS (p < 0.05). On day 10, total TV reduction for SF and PS were 3.70 ± 0.10 and 2.52 ± 0.30 log PFU/plant, respectively. Under the environmental scanning electron microscope (ESEM) observation, the leaf surfaces of SF were visually smoother than PS, while their specific effect on virus persistence were not further characterized. Overall, this study revealed that TV persistence on microgreen leaves was plant variety dependent. In addition, this study provided a preliminary estimation on the risk of HuNoV contamination in a microgreen production system which will aim the future development of prevention and control measures.

Poultry waste management practices in Bangladesh: Farmer's perceptions, and food and environmental hazards

Objective

The poultry industry plays a key role in developing socio-economic and health sectors in Bangladesh. Poultry waste is a potential environmental threat as untreated poultry waste is used in vegetable gardens. The study aimed to investigate the current situation of small-scale poultry farms and their waste management practices in selected areas of Bangladesh and detect Escherichia coli and Salmonella in vegetables from farms using untreated poultry waste as fertilizer.

Materials and Methods

A structured questionnaire-based survey was conducted in 86 small-scale poultry farms from different upazilas of Mymensingh and Khulna districts. 104 samples, including vegetables, poultry litter, water, and soil, were collected from vegetable gardens, ponds, fields, and wet markets in Mymensingh district to detect microbial contamination. Bacteria were identified based on their growth and colony morphology on selective media and motility tests. The presence of E. coli and Salmonella was confirmed by polymerase chain reaction (PCR) using a commercial PCR kit.

Results

The survey revealed that mostly middle-aged males were involved in poultry farming. Most of the farmers had primary education and engaged in farming for about 5 years without training. In the study area, 37% of farmers collected droppings daily in the morning and used them as organic fertilizer. About 58% of farmers did not know the hygienic handlings of droppings and faced health problems. In PCR, either E. coli or Salmonella or both were confirmed in vegetables, litter, soil, and pond water.

Conclusion

Appropriate poultry waste management practices can reduce the possible contamination of microbial agents in the human food chain.

Whole-Genome Analysis of blaNDM-Bearing Proteus mirabilis Isolates and mcr-1-Positive Escherichia coli Isolates Carrying blaNDM from the Same Fresh Vegetables in China

The global spread of colistin or carbapenem-resistant Enterobacteriaceae (CRE) has been a pressing threat to public health. Members of Enterobacteriaceae, especially Proteus mirabilis and Escherichia coli, have been prevalent foodborne pathogens and such pathogens from fresh vegetables have triggered foodborne illness in China. However, reports about CRE, especially P. mirabilis from fresh vegetables, are still lacking. In this study, we identified five bla_NDM-positive P. mirabilis and five bla_NDM-positive generic E. coli concurrently from five fresh vegetables in two markets from China, and four of the five E. coli also carried mcr-1. The 10 isolates were characterized with methods including antimicrobial susceptibility testing, conjugation, whole-genome sequencing and phylogenetic analysis. All 10 isolates were multidrug-resistant (MDR). bla_NDM-5 in five E. coli isolates and one P. mirabilis carrying bla_NDM-5 was located on similarly transferable IncX3 plasmids, while transferably untypable plasmids were the carriers of bla_NDM-1 in four P. mirabilis isolates from different types of vegetables/markets. mcr-1 in the four bla_NDM-₅-positive E. coli was located on similarly non-conjugative IncHI2 MDR plasmids lacking transfer region. Notably, ISCR1 complex class 1 integron capable of capturing bla_NDM-1 was found on all untypable plasmids from P. mirabilis, and five copies of ISCR1 complex class 1 integron containing bla_NDM-1 even occurred in one P. mirabilis, which showed high-level carbapenem resistance. Plasmid and phylogenetic analysis revealed that the bla_NDM-positive P. mirabilis and E. coli from fresh vegetables might be derived from animals and transmitted to humans via the food chain. The concurrence of bla_NDM-positive P. mirabilis and E. coli carrying both mcr-1 and bla_NDM in different types of fresh vegetables eaten raw is alarming and threatens food safety. Sustained surveillance of these foodborne pathogens among fresh vegetables is urgent to ensure the health of food consumers. We report for the first time the concurrence of bla_NDM-positive P. mirabilis and mcr-1-bearing E. coli carrying bla_NDM from the same fresh vegetables.

Metagenomic-based surveillance systems for antibiotic resistance in non-clinical settings

The success of antibiotics as a therapeutic agent has led to their ineffectiveness. The continuous use and misuse in clinical and non-clinical areas have led to the emergence and spread of antibiotic-resistant bacteria and its genetic determinants. This is a multi-dimensional problem that has now become a global health crisis. Antibiotic resistance research has primarily focused on the clinical healthcare sectors while overlooking the non-clinical sectors. The increasing antibiotic usage in the environment - including animals, plants, soil, and water - are drivers of antibiotic resistance and function as a transmission route for antibiotic resistant pathogens and is a source for resistance genes. These natural compartments are interconnected with each other and humans, allowing the spread of antibiotic resistance via horizontal gene transfer between commensal and pathogenic bacteria. Identifying and understanding genetic exchange within and between natural compartments can provide insight into the transmission, dissemination, and emergence mechanisms. The development of high-throughput DNA sequencing technologies has made antibiotic resistance research more accessible and feasible. In particular, the combination of metagenomics and powerful bioinformatic tools and platforms have facilitated the identification of microbial communities and has allowed access to genomic data by bypassing the need for isolating and culturing microorganisms. This review aimed to reflect on the different sequencing techniques, metagenomic approaches, and bioinformatics tools and pipelines with their respective advantages and limitations for antibiotic resistance research. These approaches can provide insight into resistance mechanisms, the microbial population, emerging pathogens, resistance genes, and their dissemination. This information can influence policies, develop preventative measures and alleviate the burden caused by antibiotic resistance.

Meta-analysis of the prevalence of the main human pathogens in vegetables, with emphasis on lettuce

This meta-analysis aims to summarize the available information on the prevalence of the main human pathogenic microorganisms in vegetables, with emphasis on lettuce (Lactuca sativa). The database searches included scientific papers from 1980 to 2019, without language restrictions. Inclusion criteria were prevalence or incidence studies published in peer-reviewed journals reporting the total number of vegetable samples studied and the number of samples positive for the presence of the studied pathogens. The target pathogens were grouped into the following categories: bacteria, parasites and viruses. Results of different vegetable types, years of sampling, analyzed regions or species of microorganisms reported in the same article were considered as different studies. Therefore, each scientific article may contain several studies. Multilevel random-effect meta-analysis models were fitted to estimate the mean occurrence rate of pathogenic microorganisms and to compare them with different factors potentially associated with the outcome. Overall, the prevalence of bacterial, parasitic and viral pathogens in vegetables was relatively low. The mean prevalence of bacterial hazards was < 0.023, with the exception of S. aureus, whose prevalence was estimated at 0.096. The mean occurrence rates of parasites and viruses were 0.067 (95 % CI: 0.056-0.080) and 0.079 (95 % CI: 0.054-0.113), respectively. The prevalence of pathogenic E. coli and parasites increased as the year of publication of the scientific articles progressed, whereas the prevalence of the other bacterial pathogens and enteric viruses was steady. The types of vegetables evaluated did not affect pathogen prevalence. The prevalence of pathogenic microorganisms differed according to the continent of origin, except for E. coli O157:H7 and parasites. The prevalence of pathogens in vegetables is of public health importance, especially in vegetable types that are eaten raw, without thermal treatment to inactivate pathogens. This meta-analysis results show the need to apply proper sanitation methods to treat raw vegetables in order to avoid foodborne infections.

Plasmon-Enhanced Bimodal Nanosensors: An Enzyme-Free Signal Amplification Strategy for Ultrasensitive Detection of Pathogens

Increasing foodborne illnesses have led to global health and economic burdens. E. coli O157:H7 is one of the most common disease-provoking pathogens and known to be lethal Shiga toxin-producing E. coli (STEC) strains. With a low infection dose in addition to person-to-person transmission, STEC infections are easily spread. As a result, specific and rapid testing methods to identify foodborne pathogens are urgently needed. Nanozymes have emerged as enzyme-mimetic nanoparticles, demonstrating intrinsic catalytic activity that could allow for rapid, specific, and accurate pathogen identification in the agrifood industry. In this study, we developed a sensitive nanoplatform based on the traditional ELISA assay with the synergistic properties of gold and iron oxide nanozymes, replacing the conventional enzyme horseradish peroxidase (HRP). We designed an easily interchangeable sandwich ELISA composed of a novel, multifunctional magneto-plasmonic nanosensor (MPnS) with target antibodies (MPnS-Ab). Our experiments demonstrate a 100-fold increase in catalytic activity in comparison to HRP with observable color changes within 15 min. Results further indicate that the MPnS-Ab is highly specific for E. coli O157:H7. Additionally, effective translatability of catalytic activity of the MPnS technology in the lateral flow assay (LFA) platform is also demonstrated for E. coli O157:H7 detection. As nanozymes display more stability, tunable activity, and multi-functionality than natural enzymes, our platform could provide customizable, low-cost assay that combines high specificity with rapid detection for a variety of pathogens in a point-of-care setup.

Extraction of the DNA of Giardia lamblia isolated from vegetables and fruits in a simplified way and its diagnosis using Nested-PCR

Giardiasis is one of the main diseases transmitted by food contaminated with infectious stages. It was usually spread through freshly eaten food. In this study, this parasite was diagnosed based on microscopic diagnosis of isolated samples of vegetables and fruits, as well as molecular diagnosis. The possibility of isolating parasites from vegetables and fruits and extract DNA to be used in most laboratories were verified in this study .The prevalence of Giardia lamblia were estimated on vegetables and fruits without the need to purchase a special extraction kit. .The prevalence of Giardia on fresh vegetables was estimated by using wet direct swab with Lugol's iodine dye in microscopic examination, at a rate of 4 positive samples out of 230 of all studied species, or 1.7%. DNA extraction was carried out for all samples, and 102 DNA samples were extracted from all samples, with a percentage of 44.3%. Moreover, the shown results of the nested PCR test for the 16 S rRNA gene on the obtained DNA the prevalence of Giardia lamblia at a rate of 5.9% from DNA samples isolated from vegetables and fruits.

Antimicrobial Resistance, Biocide Tolerance, and Bacterial Diversity of a Dressing Made from Coriander and Parsley after Application of Treatments Using High Hydrostatic Pressure Alone or in Combination with Moderate Heat

The effects of high-hydrostatic pressure (HP) treatments (450 and 600 megapascals, MPa, for 5 min at temperatures of 22 °C and 50 °C) on the microbiota of a coriander and parsley dressing was studied via culture-dependent and culture-independent approaches. Samples were refrigerated for 20 days, with periodic counts of the culture media supplemented with, or without, antimicrobials. HP-treated samples showed significantly lower viable cell counts compared to untreated controls. Only the control samples yielded bacterial growth on media with antimicrobials (imipenem, cefotaxime, benzalkonium chloride), including mostly Pseudomonas and Lactobacillus. Bacillus and Paenibacillus were identified from pressurized samples. Few isolates showed higher tolerance to some of the biocides tested. Pseudomonads showed outstanding resistance to meropenem and ceftazidime. According to high-throughput sequencing analysis, the microbiota of the dressing control samples changes during storage, with a reduction in the relative abundance of Proteobacteria and an increase in Firmicutes. The composition of the residual microbiota detected during storage was highly dependent on the pressure applied, and not on the treatment temperature.

Socioeconomic Characteristics Associated with Farming Practices, Food Safety and Security in the Production of Fresh Produce—A Case Study including Small-Scale Farmers in KwaZulu-Natal (South Africa)

Farmer practices may influence the microbial quality and safety of fresh produce. The increasing demands to create ready-to-eat (RTE) fresh produce while providing potential niche markets for smallholder farmers might be contributing to increased numbers of fresh produce-associated foodborne disease outbreaks. This study determined the demographic and socioeconomic characteristics and farmer hygiene practices of farmers using open-ended questionnaires and key informant interviews. Additionally, the relationships between farmer socioeconomic characteristics and hygiene practices were statistically analyzed. The semi-organic smallholder farmer population and the farmworkers of the organic farm were female-dominated. Tertiary education was a predominant characteristic in the organic and semi-conventional workforces. While the semi-organic and semi-conventional farms relied on a combination of ‘store-bought’ synthetic and composted organic fertilizers, the organic farm owner only used composted organic fertilizer. The irrigation water sources varied amongst the farm types. However, most of the semi-organic farmers did not pre-treat irrigation water prior to use. The irrigation water source and fertilizer type selected by farmers varied and might affect the microbial quality and safety of fresh produce. Socioeconomic factors such as gender and education may influence farmer hygiene practices. These characteristics should therefore be considered when planning farmer support interventions.

Antimicrobial Resistance Development Pathways in Surface Waters and Public Health Implications

Human health is threatened by antibiotic-resistant bacteria and their related infections, which cause thousands of human deaths every year worldwide. Surface waters are vulnerable to human activities and natural processes that facilitate the emergence and spread of antibiotic-resistant bacteria in the environment. This study evaluated the pathways and drivers of antimicrobial resistance (AR) in surface waters. We analyzed antibiotic resistance healthcare-associated infection (HAI) data reported to the CDC's National Healthcare Safety Network to determine the number of antimicrobial-resistant pathogens and their isolates detected in healthcare facilities. Ten pathogens and their isolates associated with HAIs tested resistant to the selected antibiotics, indicating the role of healthcare facilities in antimicrobial resistance in the environment. The analyzed data and literature research revealed that healthcare facilities, wastewater, agricultural settings, food, and wildlife populations serve as the major vehicles for AR in surface waters. Antibiotic residues, heavy metals, natural processes, and climate change were identified as the drivers of antimicrobial resistance in the aquatic environment. Food and animal handlers have a higher risk of exposure to resistant pathogens through ingestion and direct contact compared with the general population. The AR threat to public health may grow as pathogens in aquatic systems adjust to antibiotic residues, contaminants, and climate change effects. The unnecessary use of antibiotics increases the risk of AR, and the public should be encouraged to practice antibiotic stewardship to decrease the risk.

Applications of Essential Oils as Antibacterial Agents in Minimally Processed Fruits and Vegetables—A Review

Microbial foodborne diseases are a major health concern. In this regard, one of the major risk factors is related to consumer preferences for “ready-to-eat” or minimally processed (MP) fruits and vegetables. Essential oil (EO) is a viable alternative used to reduce pathogenic bacteria and increase the shelf-life of MP foods, due to the health risks associated with food chlorine. Indeed, there has been increased interest in using EO in fresh produce. However, more information about EO applications in MP foods is necessary. For instance, although in vitro tests have defined EO as a valuable antimicrobial agent, its practical use in MP foods can be hampered by unrealistic concentrations, as most studies focus on growth reductions instead of bactericidal activity, which, in the case of MP foods, is of utmost importance. The present review focuses on the effects of EO in MP food pathogens, including the more realistic applications. Overall, due to this type of information, EO could be better regarded as an “added value” to the food industry.

Microbiota Analysis and Microbiological Hazard Assessment in Chinese Chive (Allium tuberosum Rottler) Depending on Retail Types

Chinese chive (Allium tuberosum Rottler) has potential risks associated with pathogenic bacterial contamination as it is usually consumed raw. In this study, we investigated the microbiota of Chinese chives purchased from traditional markets and grocery stores in March (Spring) and June (Summer) 2017. Differences in bacterial diversity were observed, and the microbial composition varied across sampling times and sites. In June, potential pathogenic genera, such as Escherichia, Enterobacter, and Pantoea, accounted for a high proportion of the microbiota in samples purchased from the traditional market. A large number of pathogenic bacteria (Acinetobacter lwoffii, Bacillus cereus, Klebsiella pneumoniae, and Serratia marcescens) were detected in the June samples at a relatively high rate. In addition, the influence of the washing treatment on Chinese chive microbiota was analyzed. After storage at 26°C, the washing treatment accelerated the growth of enterohemorrhagic Escherichia coli (EHEC) because it caused dynamic shifts in Chinese chive indigenous microbiota. These results expand our knowledge of the microbiota in Chinese chives and provide data for the prediction and prevention of food-borne illnesses.

Characteristics and Global Occurrence of Human Pathogens Harboring Antimicrobial Resistance in Food Crops: A Scoping Review

Background

The role of the crop environment as a conduit for antimicrobial resistance (AMR) through soil, water, and plants has received less attention than other sectors. Food crops may provide a link between the agro-environmental reservoir of AMR and acquisition by humans, adding to existing food safety hazards associated with microbial contamination of food crops.

Objectives

The objectives of this review were: (1) to use a systematic methodology to characterize AMR in food crop value chains globally, and (2) to identify knowledge gaps in understanding exposure risks to humans.

Methods

Four bibliographic databases were searched using synonyms of AMR in food crop value chains. Following two-stage screening, phenotypic results were extracted and categorized into primary and secondary combinations of acquired resistance in microbes of concern based on established prioritization. Occurrence of these pathogen-AMR phenotype combinations were summarized by sample group, value chain stage, and world region. Sub-analyses on antimicrobial resistance genes (ARG) focused on extended-spectrum beta-lactamase and tetracycline resistance genes.

Results

Screening of 4,455 citations yielded 196 studies originating from 49 countries, predominantly in Asia (89 studies) and Africa (38). Observations of pathogen-phenotype combinations of interest were reported in a subset of 133 studies (68%). Primary combinations, which include resistance to antimicrobials of critical importance to human medicine varied from 3% (carbapenem resistance) to 13% (fluoroquinolones), whereas secondary combinations, which include resistance to antimicrobials also used in agriculture ranged from 14% (aminoglycoside resistance) to 20% (aminopenicillins). Salad crops, vegetables, and culinary herbs were the most sampled crops with almost twice as many studies testing post-harvest samples. Sub-analysis of ARG found similar patterns corresponding to phenotypic results.

Discussion

These results suggest that acquired AMR in opportunistic and obligate human pathogens is disseminated throughout food crop value chains in multiple world regions. However, few longitudinal studies exist and substantial heterogeneity in sampling methods currently limit quantification of exposure risks to consumers. This review highlights the need to include agriculturally-derived AMR in monitoring food safety risks from plant-based foods, and the challenges facing its surveillance.

Contamination of Fresh Produce with Antibiotic-Resistant Bacteria and Associated Risks to Human Health: A Scoping Review

Fresh produce, when consumed raw, can be a source of exposure to antimicrobial residues, antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs) of clinical importance. This review aims to determine: (1) the presence and abundance of antimicrobial residues, ARB and ARGs in fresh agricultural products sold in retail markets and consumed raw; (2) associated health risks in humans; and (3) pathways through which fresh produce becomes contaminated with ARB/ARGs. We searched the Ovid Medline, Web of Science and Hinari databases as well as grey literature, and identified 40 articles for inclusion. All studies investigated the occurrence of multidrug-resistant bacteria, and ten studies focused on ARGs in fresh produce, while none investigated antimicrobial residues. The most commonly observed ARB were E. coli (42.5%) followed by Klebsiella spp. (22.5%), and Salmonella spp. (20%), mainly detected on lettuce. Twenty-five articles mentioned health risks from consuming fresh produce but none quantified the risk. About half of the articles stated produce contamination occurred during pre- and post-harvest processes. Our review indicates that good agricultural and manufacturing practices, behavioural change communication and awareness-raising programs are required for all stakeholders along the food production and consumption supply chain to prevent ARB/ARG exposure through produce.

The Fate of Foodborne Pathogens in Manure Treated Soil

The aim of this review was to provide an update on the complex relationship between manure application, altered pathogen levels and antibiotic resistance. This is necessary to protect health and improve the sustainability of this major farming practice in agricultural systems based on high levels of manure production. It is important to consider soil health in relation to environment and land management practices in the context of the soil microflora and the introduction of pathogens on the health of the soil microbiome. Viable pathogens in manure spread on agricultural land may be distributed by leaching, surface run-off, water source contamination and contaminated crop removal. Thus it is important to understand how multiple pathogens can persist in manures and on soil at farm-scale and how crops produced under these conditions could be a potential transfer route for zoonotic pathogens. The management of pathogen load within livestock manure is a potential mechanism for the reduction and prevention of outbreaks infection with Escherichia coli, Listeria Salmonella, and Campylobacter. The ability of Campylobacter, E. coli, Listeria and Salmonella to combat environmental stress coupled with their survival on food crops and vegetables post-harvest emphasizes the need for further study of these pathogens along with the emerging pathogen Providencia given its link to disease in the immunocompromised and its’ high levels of antibiotic resistance. The management of pathogen load within livestock manure has been widely recognized as a potential mechanism for the reduction and prevention of outbreaks infection but any studies undertaken should be considered as region specific due to the variable nature of the factors influencing pathogen content and survival in manures and soil. Mediocre soils that require nutrients could be one template for research on manure inputs and their influence on soil health and on pathogen survival on grassland and in food crops.

Application of essential oils in packaging films for the preservation of fruits and vegetables: A review

Fruits and vegetables are highly perishable in nature. Several factors could affect the quality and shelf life of fruits and vegetables. Packaging materials (usually made up of polymers, proteins, lipids, polysaccharides, etc.,) are incorporated with essential oil (EO) which is high in antimicrobial and antioxidant compounds that can enhance the shelf life of fruits and vegetables without affecting their quality. However, the use of EO for postharvest preservation can alter the organoleptic properties of fresh produce. Exploiting synergistic interactions between several EOs, encapsulation of EO, or combining EO with non-thermal techniques such as irradiation, UV-C, cold plasma, ultrasound, etc., may help in preventing the spoilage of food products at lower concentrations without altering their organoleptic properties. This review aims to discuss the overview and current scenario of packaging film with EO for the preservation of fruit and vegetables. We have also discussed the spoilage mechanism of fruits and vegetables, mode of action of EOs, and the effect of EO with packaging film on antimicrobial and sensory properties of fruits and vegetables.

Prevalence, Enterotoxigenic Potential and Antimicrobial Resistance of Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus (MRSA) Isolated from Algerian Ready to Eat Foods

Staphylococcus aureus causes a foodborne intoxication due to the production of enterotoxins and shows antimicrobial resistance, as in the case of methicillin-resistant strains (MRSA). Herein, we analyzed 207 ready-to-eat foods collected in Algeria, reporting a S. aureus prevalence of 23.2% (48/207) and respective loads of coagulase positive staphylococci (CPS) ranging from 1.00 ± 0.5 to 5.11 ± 0.24 Log CFU/g. The 48 S. aureus isolates were widely characterized by staphylococcal enterotoxin gene (SEg)-typing and 16S-23S rDNA intergenic spacer region (ISR)-PCR, as well as by detecting tst and mecA genes, genetic determinants of toxic shock syndrome toxin-1 and methicillin resistance, respectively. We found that the S. aureus isolates belonged to seven different SEg-types harboring the following combinations of genes: (1) selW, selX; (2) egc (seG, seI, seM, seN, seO), selW, selX; (3) seA, seH, seK, seQ, selW, selX; (4) seB, selW, selX; (5) seD, selJ, seR, selW, selX; (6) seH, selW, selX, selY; and (7) seA, egc, selW, selX, while among these, 2.1% and 4.2% were tst- and mecA- (staphylococcal chromosomal cassette mec-type IV) positive, respectively. Selected strains belonging to the 12 detected ISR-types were resistant towards antimicrobials including benzylpenicillin, ofloxacin, erythromycin, lincomycin, tetracyclin, kanamycin, oxacillin, and cefoxitin; 8.3% (1/12) were confirmed as MRSA and 16.7% (2/12) were multidrug resistant. The present study shows the heterogeneity of the S. aureus population in Algerian ready-to-eat foods as for their toxigenic potential and antimicrobial resistance, shedding the light on the quality and safety related to the consume of ready-to-eat foods in Algeria.

Implementation of Food Safety Management Systems along with Other Management Tools (HAZOP, FMEA, Ishikawa, Pareto). The Case Study of Listeria monocytogenes and Correlation with Microbiological Criteria

The food industry’s failure in planning and designing of and in implementing a Food Safety Management System and its foundation elements leads, in most instances, to compromised food safety and subsequent foodborne illness outbreaks. This phenomenon was noticed, worldwide, for all food processors, but with a much higher incidence in the medium- and small-sized food processing plants. Our study focuses on the importance of Food Safety Management System (FSMS), Critical Control Points Hazard Analysis (HACCP) and the Prerequisite Programs (PRPs) as the foundation of HACCP, in preventing foodborne outbreaks. For emphasis, we make use of the example of organizational food safety culture failures and the lack of managerial engagement which resulted in a multi-state listeriosis outbreak in USA. Moreover, we correlate this with microbiological criteria. Implementation of food safety management systems (ISO 22000:2018) along with incorporation of management tools such as HAZOP, FMEA, Ishikawa and Pareto have proved to be proactive in the maintenance of a positive food safety culture and prevention of cross-contamination and fraud.

Current Update on Intrinsic and Acquired Colistin Resistance Mechanisms in Bacteria

Colistin regained global interest as a consequence of the rising prevalence of multidrug-resistant Gram-negative Enterobacteriaceae. In parallel, colistin-resistant bacteria emerged in response to the unregulated use of this antibiotic. However, some Gram-negative species are intrinsically resistant to colistin activity, such as Neisseria meningitides, Burkholderia species, and Proteus mirabilis. Most identified colistin resistance usually involves modulation of lipid A that decreases or removes early charge-based interaction with colistin through up-regulation of multistep capsular polysaccharide expression. The membrane modifications occur by the addition of cationic phosphoethanolamine (pEtN) or 4-amino-l-arabinose on lipid A that results in decrease in the negative charge on the bacterial surface. Therefore, electrostatic interaction between polycationic colistin and lipopolysaccharide (LPS) is halted. It has been reported that these modifications on the bacterial surface occur due to overexpression of chromosomally mediated two-component system genes (PmrAB and PhoPQ) and mutation in lipid A biosynthesis genes that result in loss of the ability to produce lipid A and consequently LPS chain, thereafter recently identified variants of plasmid-borne genes (mcr-1 to mcr-10). It was hypothesized that mcr genes derived from intrinsically resistant environmental bacteria that carried chromosomal pmrC gene, a part of the pmrCAB operon, code three proteins viz. pEtN response regulator PmrA, sensor kinase protein PmrAB, and phosphotransferase PmrC. These plasmid-borne mcr genes become a serious concern as they assist in the dissemination of colistin resistance to other pathogenic bacteria. This review presents the progress of multiple strategies of colistin resistance mechanisms in bacteria, mainly focusing on surface changes of the outer membrane LPS structure and other resistance genetic determinants. New handier and versatile methods have been discussed for rapid detection of colistin resistance determinants and the latest approaches to revert colistin resistance that include the use of new drugs, drug combinations and inhibitors. Indeed, more investigations are required to identify the exact role of different colistin resistance determinants that will aid in developing new less toxic and potent drugs to treat bacterial infections. Therefore, colistin resistance should be considered a severe medical issue requiring multisectoral research with proper surveillance and suitable monitoring systems to report the dissemination rate of these resistant genes.

Bacteriological safety of sprouts: A brief review

The germination process causes changes in the chemical composition of seeds that improves the nutritional value of sprouts, while decreasing their microbiological safety, since the germination conditions are ideal for bacterial growth as well. This review explores the bacteriological safety of sprouts and their involvement in foodborne illness outbreaks, worldwide. Additionally, approaches to improve the shelf-life and microbiological safety of sprouts are discussed. According to the literature, sprout consumption is associated with more than 60 outbreaks of foodborne illness worldwide, since 1988. Alfalfa sprouts were most commonly involved in outbreaks and the most commonly implicated pathogens were Salmonella and pathogenic Escherichia coli (especially, Shiga toxin producing E. coli). In the pre-harvest stage, the implementation of good agricultural practices is an important tool for producing high-quality seeds. In the post-harvest stage, several methods of seed decontamination are used commercially, or have been investigated by researchers. After germination, seedlings should be kept under refrigeration and, if possible, cooked before consumption. Finally, microbiological analyses should be performed at all stages to monitor the hygiene of the sprout production process.

Salmonella, Food Safety and Food Handling Practices

Salmonellosis is the second most reported gastrointestinal disorder in the EU resulting from the consumption of Salmonella-contaminated foods. Symptoms include gastroenteritis, abdominal cramps, bloody diarrhoea, fever, myalgia, headache, nausea and vomiting. In 2018, Salmonella accounted for more than half of the numbers of foodborne outbreak illnesses reported in the EU. Salmonella contamination is mostly associated with produce such as poultry, cattle and their feeds but other products such as dried foods, infant formula, fruit and vegetable products and pets have become important. Efforts aimed at controlling Salmonella are being made. For example, legislation and measures put in place reduced the number of hospitalizations between 2014 and 2015. However, the number of hospitalizations started to increase in 2016. This calls for more stringent controls at the level of government and the private sector. Food handlers of "meat processing" and "Ready to Eat" foods play a crucial role in the spread of Salmonella. This review presents an updated overview of the global epidemiology, the relevance of official control, the disease associated with food handlers and the importance of food safety concerning salmonellosis.

Non-Destructive Detection Pilot Study of Vegetable Organic Residues Using VNIR Hyperspectral Imaging and Deep Learning Techniques

Contamination is a critical issue that affects food consumption adversely. Therefore, efficient detection and classification of food contaminants are essential to ensure food safety. This study applied a visible and near-infrared (VNIR) hyperspectral imaging technique to detect and classify organic residues on the metallic surfaces of food processing machinery. The experimental analysis was performed by diluting both potato and spinach juices to six different concentration levels using distilled water. The 3D hypercube data were acquired in the range of 400-1000 nm using a line-scan VNIR hyperspectral imaging system. Each diluted residue in the spectral domain was detected and classified using six classification methods, including a 1D convolutional neural network (CNN-1D) and five pre-processing methods. Among them, CNN-1D exhibited the highest classification accuracy, with a 0.99 and 0.98 calibration result and a 0.94 validation result for both spinach and potato residues. Therefore, in comparison with the validation accuracy of the support vector machine classifier (0.9 and 0.92 for spinach and potato, respectively), the CNN-1D technique demonstrated improved performance. Hence, the VNIR hyperspectral imaging technique with deep learning can potentially afford rapid and non-destructive detection and classification of organic residues in food facilities.

A Double-Edged Sword of Surfactant Effect on Hydrophobic Surface Broccoli Leaf as a Model Plant: Promotion of Pathogenic Microbial Contamination and Improvement to Disinfection Efficiency of Ozonated Water

Pathogenic microbial contamination is significantly influenced by the crop surface properties and surfactant use, which are crucial factors for the postharvest washing process. However, there is little information on the interaction between surfactant and food pathogens on food crops. Thus, this study (1) investigated whether the attachment of Salmonella increases as pesticides denature epicuticular wax crystals and (2) tested if the antibacterial effect of ozonated water can be improved on waxy produce surfaces by adding surfactant to ozonated water. As a result, significantly lower levels of Salmonella Typhimurium attached to waxy leaf surfaces than they did to glossy and pesticide-treated waxy leaf surfaces (3.28 as opposed to 4.10 and 4.32 Log colony forming units (CFU)/cm2, respectively), suggesting that the pesticide containing a surfactant application increased the attachment of S. Typhiumurium on waxy leaf surfaces. There was no significant washing effect on waxy leaf surfaces washed with ozonated water. On the other hand, S. Typhimurium were not detected on waxy leaf surfaces after washing with surfactant-added ozonated water.

Microbial and physicochemical assessment of irrigation water treatment methods

AIMS

The presence of foodborne pathogens in preharvest agricultural water has been identified as a potential contamination source in outbreak investigations, driving markets and auditing bodies to begin requiring water treatment for high-risk produce. Therefore, it is essential that we identify water treatment methods which are effective as well as practical in their application on farm.

METHODS AND RESULTS

In this work, we evaluated two sanitizers which are most prominent in preharvest agricultural water treatment (calcium hypochlorite (free chlorine: 3-5 ppm) and peracetic acid (PAA: 5 ppm)), an EPA registered antimicrobial device (ultraviolet light (UV)), in addition to a combination approach (chlorine + UV, PAA + UV). Treatments were evaluated for their ability to inactivate total coliforms and generic Escherichia coli and consistency in treatment efficacy over 1 h of operation. Physicochemical variables were measured along with microbial populations at 0, 5, 15, 30, 45 and 60 min of operation. Escherichia coli and coliform counts showed a significant (P < 0·05) reduction after treatment, with combination and singular treatments equally effective at inactivating E. coli and coliforms. A significant increase (P < 0·05) in oxidation-reduction potential was seen during water treatment (Chlorine; UV + Chlorine), and a significant reduction (P < 0·05) in pH was seen after PAA and PAA + UV treatments (60 min).

CONCLUSION

Overall, the results indicate that all treatments evaluated are equally efficacious for inactivating E. coli and coliforms present in surface agricultural water.

SIGNIFICANCE AND IMPACT OF THE STUDY

This information when paired with challenge studies targeting foodborne pathogens of interest can be used to support grower decisions when selecting and validating a preharvest agricultural water treatment programme.