The European Union One Health 2020 Zoonoses Report

Comparing Campylobacter jejuni to three other enteric pathogens in OligoMM12 mice reveals pathogen-specific host and microbiota responses

Campylobacter jejuni, non-typhoidal Salmonella spp., Listeria monocytogenes and enteropathogenic/enterohemorrhagic Escherichia coli (EPEC/EHEC) are leading causes of food-borne illness worldwide. Citrobacter rodentium has been used to model EPEC and EHEC infection in mice. The gut microbiome is well-known to affect gut colonization and host responses to many food-borne pathogens. Recent progress has established gnotobiotic mice as valuable models to study how microbiota affect the enteric infections by S. Typhimurium, C. rodentium and L. monocytogenes. However, for C. jejuni, we are still lacking a suitable gnotobiotic mouse model. Moreover, the limited comparability of data across laboratories is often negatively affected by variations between different research facilities or murine microbiotas. In this study, we applied the standardized gnotobiotic OligoMM12 microbiota mouse model and compared the infections in the same facility. We provide evidence of robust colonization and significant pathological changes in OligoMM12 mice following infection with these pathogens. Moreover, we offer insights into pathogen-specific host responses and metabolite signatures, highlighting the advantages of a standardized mouse model for direct comparisons of factors influencing the pathogenesis of major food-borne pathogens. Notably, we reveal for the first time that C. jejuni stably colonizes OligoMM12 mice, triggering inflammation. Additionally, our comparative approach successfully identifies pathogen-specific responses, including the detection of genes uniquely associated with C. jejuni infection in humans. These findings underscore the potential of the OligoMM12 model as a versatile tool for advancing our understanding of food-borne pathogen interactions.

Complete and draft genome sequences of Salmonella Wandsworth and Salmonella Stanley isolated from insect-based food products

Detection of Salmonella in insects is rarely described, especially in insect-based food stuff. Here, we report the genome sequences of two Salmonella isolates belonging to Salmonella enterica subsp. enterica serovar (S.) Stanley and S. Wandsworth isolated from a ready-to-eat insect-based food sample (whole dried salted crickets), imported to Germany.

Molecular epidemiology of Salmonella Enteritidis in humans and animals in Spain

Salmonella Enteritidis, the most prevalent serovar-causing human gastroenteritis, has been traditionally linked to poultry sources. Although antimicrobial resistance (AMR) is not common in this serovar, increasing levels of resistance to fluoroquinolones and ampicillin have been reported in the last few years. Here, 298 isolates retrieved from different sources (human, livestock, wildlife, food, and environment) and years (2002-2021) in Spain were analyzed to evaluate their diversity, the distribution of AMR-conferring genes (ARGs), and mutations and reconstruct the epidemiology of infection due to this serovar. Isolates were clustered in two major clades (I and II), with strains in clade I (including 61.5% of all human isolates) displaying a pan-susceptible phenotype and not carrying AMR determinants. In contrast, clade II included 80.7% of isolates from animal/food/environmental sources, with the majority (69.8%) harboring mutations in the quinolone resistance determinant regions (QRDR). ARGs, although rare, were mostly found in clade II strains that also carried plasmid replicons, among which IncX1 was the most common. Although higher levels of phenotypic resistance were found in animal isolates, extended-spectrum beta-lactamase, plasmid-mediated AmpC, and carbapenemase-encoding genes were only found among human isolates. In summary, the majority of human and animal isolates from Spanish sources in our collection were classified in different phylogenetic branches, suggesting that additional sources are contributing to the occurrence of foodborne infections in Spain. Furthermore, the different distributions of virulence factors and ARGs in isolates from different sources and their association with specific plasmids suggest the presence of different dynamics contributing to the selection of resistant strains.

Effects of the histone-like protein on biofilm formation and pathogenicity of Listeria monocytogenes

Histone-like protein HU is essential for DNA recombination, repair, and transcriptional regulation in bacteria. However, the physiological roles of HU proteins in Listeria monocytogenes (LmHU) remain unexplored. Given the significant biofilm-forming ability of this foodborne pathogen and its associated cross-contamination risks, identifying novel control targets is critical. LmHU, as the sole double-stranded DNA-binding protein in L. monocytogenes, is a promising candidate. This study systematically explored its contributions to biofilm formation, motility, and the regulation of virulence factors. The results indicated that high levels of LmHU in vivo promoted cell cohesion, leading to a chain-like structure among L. monocytogenes. Additionally, LmHU could be secreted into the biofilm matrix, reinforcing the structure by interacting with extracellular polymeric substances. However, elevated LmHU levels inhibited bacterial motility, flagellar synthesis, and host invasion in Caco-2 cells. RNA-seq analysis revealed 374 differentially expressed genes in the Lmhu mutant relative to the wild-type strain, supporting these findings. Further enrichment analysis and validation experiments suggested that Lmhu overexpression impaired trehalose utilization. These results indicate that LmHU may serve as a potential target for novel disinfectants or therapies to reduce risks associated with L. monocytogenes in food safety and public health.

Phenotypic and Genomic Assessment of Antimicrobial Resistance and Virulence Factors Determinants in Salmonella Heidelberg Isolated from Broiler Chickens

Salmonella Heidelberg is frequently found in poultry and poultry products and is associated with antimicrobial resistance strains and infections and mortality in humans. Whole-genome sequencing is used to monitor and understand epidemiological factors related to antimicrobial resistance. This study aimed to characterize the phenotypic resistance and sequence the whole genome of Salmonella Heidelberg strains isolated from poultry products in Brazil. Fourteen Salmonella Heidelberg strains isolated from whole broiler chicken carcasses and portions in Brazil between 2013 and 2019 were used in this study. Genus confirmation was performed by polymerase chain reaction. The disk diffusion test was conducted to assess the phenotypical antimicrobial susceptibility of the strains. Whole-genome sequencing was carried out to investigate the presence of antimicrobial resistance genes, plasmids, multilocus sequence typing, and virulence-associated genes. A high frequency of phenotypic resistance to cephalosporins, tetracyclines, and sulfonamides was detected. All strains had mutations in gyrA and parC and contained the genes tet(A), fosA7, and sul. The presence of genes originating from Yersinia pathogenicity islands was also detected. This study identified a high frequency of antimicrobial resistance in Salmonella Heidelberg strains from broilers slaughtered in different regions of Brazil, all belonging to the same sequence type (ST15) and associated with multiple resistance and virulence genes. The presence of the Yersinia high-pathogenicity island was detected, indicating potential virulence. These findings highlight the importance of continuously monitoring antimicrobial resistance to control and prevent foodborne infections and maintain the efficacy of treatments for human salmonellosis.

Characterization and therapeutic potential of newly isolated bacteriophages targeting the most common Salmonella serovars in Europe

Despite meticulous monitoring of Salmonella spp. throughout the food chain to ensure safer animal food products for consumers, the number of salmonellosis cases in humans continues to rise annually in Europe. Phage therapy emerges as a promising tool for controlling and eradicating Salmonella in primary production. This study aimed to fully characterize new phage therapy candidates isolated from animal sources. To achieve this, a phenotypic and genetic characterization of five phage isolates was conducted. The five phages demonstrated physical stability across a wide range of temperatures and pH levels, effectively lysing 12 different Salmonella serovars, including the most prevalent ones in the European Union in recent years, as well as multidrug-resistant strains isolated from the field. Additionally, four of the phages exhibited depolymerase production in the host range, with genomic analysis confirming that all five possessed sequences encoding for this activity, suggesting their potential as surface-disinfecting agents. Genetic analysis further revealed that the phages belong to distinct genera: Felixounavirus, Cornellvirus, Skatevirus, Agtevirus and Berlinvirus. Notably, none of the phages contained harmful sequences that could compromise their future application, such as virulence factors, antibiotic resistance genes or temperate markers. Overall, these five phages show promise as suitable candidates for phage therapy applications or phage-based Salmonella eradication strategies, where their integration in the existing biocontrol measures may enhance both food safety and public health.

Genomic epidemiology and public health implications of zoonotic monophasic Salmonella Typhimurium ST34

Background

Monophasic Salmonella Typhimurium sequence type 34 (mSTM ST34) has emerged as a significant global health threat, but our understanding of its genomic epidemiology and potential public health implications in international and regional contexts remains limited. This study aims to fill this crucial gap by assessing the genomic epidemiology of multidrug resistance (MDR) mSTM ST34, as well as its clinical characteristics and virulence.

Methods

To achieve the objectives of this study, we conducted a comprehensive genomic analysis of mSTM ST34 isolates. We obtained a global dataset comprising 13,844 strains from public databases, along with 339 strains from a regional surveillance collection in Zhejiang Province, China. This dataset aims to provide in-depth insights into antimicrobial resistance, mobile genetic elements, and pathogenicity. Additionally, we meticulously assessed the association between phenotypic profiles and clinical presentations.

Results

Our findings revealed that the prevalence of mSTM ST34 has surpassed that of the previously dominant ST19. In addition, we observed an increase in the detection of the IncQ1 plasmid, which is responsible for disseminating MDR. The prevalence of mSTM ST34 carriage was exceptionally high among children (≤12 years old) and elderly individuals (≥65 years old), with 92.6% of the isolates exhibiting MDR, including resistance to frontline antimicrobials such as third-generation cephalosporins and ciprofloxacin. Additionally, the human mSTM ST34 strain demonstrates a remarkable capacity for biofilm formation, which increases its virulence in animal models and complicates therapeutic interventions.

Conclusions

mSTM ST34 has surpassed the previously dominant ST19, and its ability to transmit across multi-species increases its potential for further human transmission. This study addresses critical gaps in our understanding of mSTM ST34 prevalence, highlighting the importance of whole genome sequencing in surveilling zoonotic pathogens.

Development and Characterization of a Polyvalent Polyclonal Antibody as a Common Capture Antibody for the Detection of Enterotoxigenic Escherichia coli in a Sandwich ELISA

Due to its low cost and simplicity, the sandwich enzyme-linked immunosorbent assay (sELISA) is a traditional technique for identifying foodborne pathogens. However, most sELISAs are designed for single foodborne pathogen detection using two specific antibodies, which capture and detect the target bacteria. This study aimed to produce and characterize a common capture polyclonal antibody for Enterotoxigenic Escherichia coli (ETEC), Salmonella Typhimurium, and Shigella flexneri (S. flexneri) by a sELISA. Rabbit polyclonal antibodies (pAbs) were generated against recombinant proteins of CsgA, FhuA, and OmpA, which we called anti-mix. The recombinant proteins generated are conserved in Escherichia coli (E. coli), Salmonella enterica serovar Typhimurium, and S. flexneri species, but not in Listeria monocytogenes (L. monocytogenes) and Enterococcus faecalis (E. faecalis). The anti-mix serum gave a title higher than 1:32,000 by an indirect ELISA using purified recombinant proteins and whole bacteria cultures of the bacteria expressing the antigens but failed to recognize L. monocytogenes and E. faecalis. In addition, a recombinant protein A was purified and used to orient the capture antibodies (anti-mix) in the sELISA. However, no statistically significant difference was found in the assay sensitivity for ETEC detection in spiked milk samples with or without protein A. The assay linearity of sELISA for ETEC detection in Phosphate-buffered saline (PBS) was from 1 × 108 to 1 × 104 cells/mL, and for spiked milk samples was 1 × 108 to 1 × 105 cells/mL. In spiked milk samples, the detection limit of ETEC was lower than PBS, which suggests a negative effect from the matrix analyzed (milk) compared to PBS.

Antibiotic-Resistant Salmonella in Animal Products Jeopardize Human Health

Despite the significance of antibiotics in treating bacterial infections, antibiotic resistance is continuously increasing, thus posing a significant threat. In addition to strains resistant to individual drugs, multidrug-resistant (MDR) and pandrug-resistant strains, are emerging. Salmonella, a primary cause of global foodborne illness, is often transmitted through animal products. Antibiotic treatment is crucial for immunocompromised individuals, such as older adults and patients with weakened immune systems, due to their increased susceptibility to severe effects. MDR Salmonella, which can arise following antibiotic use in food animals, may transfer to humans, leading to significant health challenges. The emergence of Salmonella strains resistant to carbapenems, often considered a last-resort antibiotic class, is particularly concerning. Salmonella neutralizes antibiotics through mechanisms, such as horizontal gene transfer via plasmids, efflux/influx system regulation, and enzyme production that deactivate or alter antibiotics. The rise of megaplasmids in Salmonella is particularly alarming, as it may enable resistance to a broader range of antibiotics. This review summarizes the current state of the growing threat of MDR Salmonella and underscores the urgent need for a coordinated response.

First report of T. spiralis in a wolf in Italy: An increasing health concern?

Trichinella spiralis is a zoonotic nematode parasite of worldwide distribution. It is present in Europe with important foci, particularly in Eastern countries and Spain. This species is generally associated with a domestic cycle that involves primarily pigs. It is best adapted for pigs but can also infect a wide range of other domestic, synanthropic, and wild mammals including carnivores, omnivores and scavengers. Before 2016, when T. spiralis larvae were detected in a red fox (Vulpes vulpes) in the Piacenza province (Emilia Romagna region, Northern Italy), this parasite had only been reported in Italy occasionally, being found in horses or pork products imported from Eastern Europe. We describe here the first isolation of T. spiralis in a wolf (Canis lupus) in the Lazio region, Central Italy. In the wolf specimen T. spiralis was identified in coinfection with Trichinella britovi, a species endemic in Italian wildlife. Among the Trichinella species, T. spiralis is the most frequently associated with human disease in Europe and is known to cause more severe symptoms than T. britovi. In light of wolf population expansion, the detection of T. spiralis in Central Italy implies new scenarios for the risk of human trichinellosis because of the high risk this species represents for domestic and wild pigs. Active monitoring of wildlife living in these areas is necessary to define the actual distribution of  this species and to detect its possible presence in other areas of the Italian peninsula.

A Systematic Review and Analysis of Brucella Endocarditis Cases

Endocarditis is the most common cause of death from brucellosis. The information used to guide the management of cases with Brucella endocarditis has relied on case reports/series. Risk factors related to death and other adverse outcomes in patients with Brucella endocarditis were identified by an individual-patient data analysis of all reported Brucella endocarditis cases in the literature. The keywords "Bruce" and "endocard" were used to search articles published until July 2022 on PubMed and ULAKBIM databases. Case reports/series containing patients with endocarditis caused by Brucella spp., aged ≥17 years, and with data on antimicrobial or surgical treatment were included in the study. Epidemiological, clinical, laboratory, and treatment characteristics and outcomes of 273 cases from 86 eligible articles were recorded. It was found that male gender, a Wright serum tube agglutination (STA) titer of ≥1/1280 on admission, development of heart failure due to endocarditis were independent risk factors that increase mortality, while the usage of aminoglycoside and cardiac surgical intervention for endocarditis were factors reducing mortality. Including streptomycin or gentamicin in the treatment regimen may benefit patients with Brucella endocarditis. Valve surgery could be life-saving in patients with Brucella endocarditis. An STA titer of ≥1/1280, which probably reflects long-term and advanced disease, may be used as a marker for increased mortality. However, additional and more reliable studies are needed to define the most appropriate management approach in diagnosing and treating cases with Brucella endocarditis due to the low quality of the current evidence.

Enhancing detection of STEC in the meat industry: insights into virulence of priority STEC

Detection of Shiga toxin-producing Escherichia coli (STEC) presenting high risk of human infections is challenging. In France, the latest Anses opinion categorized STEC in four groups based on their association with severe forms of clinical infection. STEC strains carrying the eae gene, particularly those of serogroups O157, O26, O111, O103, O145, O121, O45 and more recently O80 (top 8 serogroups), are usually monitored worldwide, whereas eae-negative STEC strains that are less clinically significant are not surveyed. Screening food enrichment broths with classical genetic markers (stx, eae) can overestimate the presence of highly virulent STEC, causing needless disruption and costs for food producers. Recently the updated MLG5C reference method introduced additional genetic markers (espK, espV) in the detection scheme to improve specificity and effectiveness of priority STEC detection in foodstuffs. This study, conducted on beef samples with a new method supporting the regulatory USDA-FSIS MLG5C.04 method, showed that 92% of the stx-positive samples carry stx2 alone or in association with stx1. Among the stx2-positive samples, stx2a and/or stx2d subtypes dominate. Introduction of espK, espV markers on 868 stx +/eae + beef enrichment broths reduced the number of presumptive positive results by 31%, compared to the ISO/TS 13136:2012 reference method. Subsequent analysis of the presumptive positives combining the O-group and the eae-subtype provided also a significant reduction of the number of the presumptive positive for the top 8 eae-positive STEC serogroups; and showed that O26, O103 and O157 were the most prevalent ones. Regarding the stx +/eae- samples, which are proportionally extremely predominant in beef as compared with the stx +/eae + samples, 65% of them were positive for the serogroups monitored in this study (O91, O171, O174, O148, O146, O128 O113 and O104). The high occurrence of serogroup O113 observed in beef samples is not corroborated by the clinical data reported in France. Routine testing of beef samples should be revised to prioritize a hierarchical surveillance system based only on high risk STEC (STEC carrying the eae gene) and not on all STEC. This approach would provide Food Business Operators a significant improvement, saving time and costs while maintaining a high level of product safety.

Development and application of a quadruple RT-qPCR assay for the simultaneous detection of NoV GI, NoV GII, and HAV in bivalve shellfish

To achieve rapid and simultaneous detection of NoV GI, NoV GII, and HAV, a quadruple real-time fluorescence quantitative PCR (RT-qPCR) assay was developed using MS2 bacteriophage as a process control virus. The quadruple RT-qPCR assay effectively detected NoV GI, NoV GII, HAV, and MS2 RNA with detection limits of 102 copies/μL, 103 copies/μL, 102 copies/μL, and 103 copies/μL, respectively, within 1 hour 50 minutes. The quadruple RT-qPCR assay could specifically detect NoV GI, NoV GII, HAV, and MS2 without cross-reactions with other common pathogens, demonstrating good reproducibility with intra-assay and inter-assay coefficients of variation all below 2.11%. In this study, 337 bivalve shellfish samples collected from various regions of Hebei Province were pretreated using the proteinase K-PEG 8000 precipitation-chloroform method, and viral nucleic acids were enriched and extracted from a volume of viral solution that was doubled. The developed quadruple RT-qPCR assay was used to detect NoV GI, NoV GII, and HAV in bivalve shellfish samples, and the positive rates were 19.88% (67/337), 20.47% (69/337), and 4.75% (16/337), respectively. In addition, mixed infections of NoV GI and NoV GII (10.68%, 36/337) and NoV GI and HAV (0.89%, 3/337) were observed. In all, 200 bivalve shellfish samples were randomly selected for the assay, and it was found that the total, positive, negative coincidence rates, and Kappa values of the quadruple RT-qPCR assay were 98.3%, 99.1%, 98.2%, and 0.945, respectively, compared with the single RT-qPCR assay. These results show that the developed quadruple RT-qPCR assay has comparable performance to the single RT-qPCR assay.IMPORTANCEFood-borne diseases caused by viral contamination have become a growing concern, and bivalve shellfish is a crucial source of infection, with many outbreaks of non-bacterial acute gastroenteritis associated with raw food or the use of undercooked shellfish such as oysters. As food contamination problems caused by NoV and HAV become more severe, it is important to study and establish a sensitive and efficient assay to simultaneously detect NoV and HAV by applying the MS2 process control virus for the protection of bivalve shellfish food safety and the monitoring of the above food-borne viral contamination. In addition, bivalve shellfish samples contain a large number of PCR inhibitors such as polysaccharides, lipids, and proteins, so optimization of the virus enrichment and extraction method is essential and is expected to provide a research basis for subsequent related experiments.

Growth-Inhibitory Effect of Chicken Egg Yolk Polyclonal Antibodies (IgY) on Zoonotic Pathogens Campylobacter jejuni, Salmonella spp. and Escherichia coli, In Vitro

The overuse of antibiotics in animal husbandry has driven the search for alternative strategies to combat zoonotic pathogens. Foodborne zoonotic diseases caused by pathogenic bacteria pose a significant threat to human health, and therefore food safety should be a priority. This study investigates the in vitro inhibitory effects of chicken egg yolk immunoglobulin Y (IgY) on the growth and viability of three major foodborne pathogens: Campylobacter jejuni, Salmonella spp., and Escherichia coli. IgY was isolated from immunized hen egg yolks using a modified water dilution method, and its antigen-specificity confirmed through agglutination assays. Growth inhibition was evaluated across multiple doses and time points, revealing a dose-dependent bacteriostatic effect against all tested pathogens. A single dose of IgY (0.5 mg/mL) significantly reduced C. jejuni counts by up to 7 log, while repeated doses were required for Salmonella spp. and E. coli. These findings highlight egg yolk immunoglobulin's potential as a source of sustainable, effective, ethical, readily available, and inexpensive antibiotic substitutes in livestock management. Future research will focus on validating these results in vivo and exploring large-scale production of IgY for practical application in animal healthcare.

Microbiological Analysis Conducted on Raw Milk Collected During Official Sampling in Liguria (North-West Italy) over a Ten-Year Period (2014-2023)

Milk has been consumed by humans for thousands of years for its nutritional properties. In recent years, raw milk demand has increased, valued for its authenticity and connection to local traditions. In Italy, the sale of raw milk is allowed exclusively through direct sale from the producing farm to the final consumer, either at the producing farm itself or through vending machines. However, the consumption of raw milk is not without risks. Among these, microbiological ones are relevant. These can lead to severe symptoms, particularly in vulnerable populations. For this reason, although consumers are advised to boil raw milk before consumption, producing farms in Italy are required to meet the microbiological criteria outlined in the Provision of 25 January 2007. In this retrospective study, the results of the analyses performed on 355 raw milk samples collected in Liguria between 2014 and 2023 for the detection of Campylobacter spp., Salmonella spp., Listeria monocytogenes, Staphylococcus aureus, and Escherichia coli O157 were analysed to better characterise the associated risk for consumers. The samples were collected during official controls by the local veterinary health services at vending machines of seven producing farms. Overall, six samples tested positive for C. jejuni, while only one sample tested positive for Salmonella enterica subsp. enterica, Serovar Veneziana. Listeria monocytogenes, S. aureus, and E. coli O157 were never responsible for non-compliances. Interestingly, three of the six samples positive for C. jejuni derived from the same producer. In farms where positive samples were detected, certain structural and/or operational non-compliances were identified. It can be concluded that, although the scenario in question does not present any cause for concern, it is nevertheless essential to implement a series of preventive measures in order to guarantee the safety of raw milk. These measures include the implementation of biosecurity practices, the maintenance of strict hygiene protocols during milking, and the adherence to the cold chain distribution protocol until the final stage of distribution.

Integrating MALDI-TOF Mass Spectrometry with Machine Learning Techniques for Rapid Antimicrobial Resistance Screening of Foodborne Bacterial Pathogens

Although MALDI-TOF mass spectrometry (MS) is considered as the gold standard for rapid and cost-effective identification of microorganisms in routine laboratory practices, its capability for antimicrobial resistance (AMR) detection has received limited focus. Nevertheless, recent studies explored the predictive performance of MALDI-TOF MS for detecting AMR in clinical pathogens when machine learning techniques are applied. This chapter describes a routine MALDI-TOF MS workflow for the rapid screening of AMR in foodborne pathogens, with Campylobacter spp. as a study model.

Recent advances in examining the factors influencing the efficacy of biocides against Listeria monocytogenes biofilms in the food industry: A systematic review

Controlling Listeria monocytogenes and its associated biofilms in the food industry requires various disinfection techniques, including physical, chemical, and biological treatments. Biocides, owing to their ease of use, cost-effectiveness, dissolvability in water, and efficacy against a wide range of microorganisms, are frequently selected options. Nonetheless, concerns have been raised about their efficacy in controlling L. monocytogenes biofilm, as laboratory-based and commercial studies have reported the persistence of this bacterium after cleaning and disinfection. This review systematically examined scientific studies, sourced from the Web of Science, Scopus, and PubMed databases between January 2010 and May 2024, that investigated the effectiveness of the most commonly used biocides in the food industry against L. monocytogenes biofilms. A total of 92 articles which met the screening criteria, were included, with studies utilizing biocides containing sodium hypochlorite, quaternary ammonium compounds, and peroxyacetic acid being predominant. Studies indicated that several key factors may potentially influence biocides' efficacy against L. monocytogenes biofilms. These factors included strain type (persistent, sporadic), serotype, strain origin (clinical, environmental, or food), surface type (biotic or abiotic), surface material (stainless steel, polystyrene, etc.), incubation time (biofilm age) and temperature, presence of organic matter, biocide's active agent, and the co-culture of L. monocytogenes with other bacteria. The induction of the viable but nonculturable (VBNC) state following disinfection is also a critical concern. This review aims to provide a global understanding of how L. monocytogenes biofilms respond to biocides under different treatment conditions, facilitating the development of effective cleaning and disinfection strategies in the food industry.

Antimicrobial Resistance in the Context of Animal Production and Meat Products in Poland-A Critical Review and Future Perspective

The prevalence of antimicrobial-resistant bacteria in meat and meat products is a significant public health challenge, largely driven by the excessive and inappropriate use of antimicrobials in animal husbandry. In Poland, a key meat producer in Europe, antibiotic-resistant pathogens such as Campylobacter spp., Staphylococcus spp., Enterococcus spp., Listeria monocytogenes, and Enterobacterales have been detected in meat, posing serious risks to consumers. This review examines the use of antimicrobial agents in meat production and the resulting antimicrobial resistance (AMR) in microorganisms isolated from meat products in Poland. The mechanisms of AMR, genetic factors, and prevalence in Poland are presented. It highlights key factors contributing to AMR, such as antibiotic misuse in livestock farming, and discusses the legal regulations governing veterinary drug residues in food. This review emphasizes the importance of monitoring and enforcement to safeguard public health and calls for further research on AMR in the meat industry. Antimicrobial resistance in meat and meat products in Poland is a huge challenge, requiring stricter antibiotic controls in animal husbandry and improved surveillance systems. Additionally, the impact of husbandry practices on the environment and food requires further research. Future efforts should focus on nationwide monitoring, alternative strategies to reduce antibiotic use, and stronger enforcement to combat antimicrobial resistance and protect public health.

Natural Solutions to Antimicrobial Resistance: The Role of Essential Oils in Poultry Meat Preservation with Focus on Gram-Negative Bacteria

The increase in antimicrobial resistance (AMR) is a major global health problem with implications on human and veterinary medicine, as well as food production. In the poultry industry, the overuse and misuse of antimicrobials has led to the development of resistant or multi-drug resistant (MDR) strains of bacteria such as Salmonella spp., Escherichia coli and Campylobacter spp., which pose a serious risk to meat safety and public health. The genetic transfer of resistance elements between poultry MDR bacteria and human pathogens further exacerbates the AMR crisis and highlights the urgent need for action. Traditional methods of preserving poultry meat, often based on synthetic chemicals, are increasingly being questioned due to their potential impact on human health and the environment. This situation has led to a shift towards natural, sustainable alternatives, such as plant-derived compounds, for meat preservation. Essential oils (EOs) have emerged as promising natural preservatives in the poultry meat industry offering a potential solution to the growing AMR problem by possessing inherent antimicrobial properties making them effective against a broad spectrum of pathogens. Their use in the preservation of poultry meat not only extends shelf life, but also reduces reliance on synthetic preservatives and antibiotics, which contribute significantly to AMR. The unique chemical composition of EOs, that contains a large number of different active compounds, minimizes the risk of bacteria developing resistance. Recent advances in nano-encapsulation technology have further improved the stability, bioavailability and efficacy of EOs, making them more suitable for commercial use. Hence, in this manuscript, the recent literature on the mechanisms of AMR in the most important Gram-negative poultry pathogens and antimicrobial properties of EOs on these meat isolates was reviewed. Additionally, chemical composition, extraction methods of EOs were discussed, as well as future directions of EOs as natural food preservatives. In conclusion, by integrating EOs into poultry meat preservation strategies, the industry can adopt more sustainable and health-conscious practices and ultimately contribute to global efforts to combat AMR.

The European Union One Health 2023 Zoonoses report

This report by the European Food Safety Authority and the European Centre for Disease Prevention and Control presents the results of zoonoses monitoring and surveillance activities carried out in 2023 in 27 Member States (MSs), the United Kingdom (Northern Ireland) and 10 non-MSs. Key statistics on zoonoses and zoonotic agents in humans, food, animals and feed are provided and interpreted historically. In 2023, the first and second most reported zoonoses in humans were campylobacteriosis and salmonellosis, respectively. For both agents, an increase in the absolute number of cases was observed in comparison with 2022. Fifteen MSs and the United Kingdom (Northern Ireland) reached all the established targets in poultry populations with regard to the reduction in Salmonella prevalence for the relevant serovars. Salmonella samples from carcases of various animal species, and samples for Campylobacter quantification from broiler carcases, were more frequently positive when performed by the competent authorities than when own-checks were conducted. Shiga toxin-producing Escherichia coli (STEC) was the third most reported zoonotic agent in humans, followed by Yersinia enterocolitica and Listeria monocytogenes. L. monocytogenes and West Nile virus infections were the most severe zoonotic diseases, with the highest percentage of hospitalisations among cases and the highest case fatality rates. Twenty-seven MSs and the United Kingdom (Northern Ireland) reported a slight decrease in food-borne outbreaks in 2023 overall in comparison with 2022, although the overall number of reported human cases and hospitalisations increased. Salmonella Enteritidis remained the most frequently reported causative agent for reported cases and food-borne outbreaks. Salmonella in 'eggs and egg products' was the agent/food pair of most concern. In 2023 this combination caused the largest number of outbreaks and cases among all agent/food combination and ranked second in number of hospitalisations. Salmonella was also the causative agent associated with the majority of multi-country outbreaks reported in the EU in 2023. This report also provides updates on brucellosis, echinococcosis, Q fever, rabies, toxoplasmosis, trichinellosis, tuberculosis due to Mycobacterium bovis or M. caprae, and tularaemia.

Bacillus subtilis Intraspecies Interactions Shape Probiotic Activity Against Salmonella Typhimurium

Commercial probiotics are often formulated as multi-strain cocktails, but the effects of social interactions, particularly between strains of a species, are often neglected, despite their potential to contribute to higher-order interactions where these interactions could affect those with a third party. In this study, we investigated the probiotic potential of a collection of Bacillus subtilis strains against Salmonella Typhimurium in single-strain and mixed cultures. The results indicate a promising probiotic potential of B. subtilis as 38 out of 39 strains significantly inhibited the growth of S. Typhimurium. Next, we tested the effect of mixing B. subtilis strains that differ in their inhibitory potency against S. Typhimurium. The results show that strong inhibition by one strain can be significantly reduced by mixing with a less effective strain. Moreover, mixing similarly effective strains mostly resulted in a decreased growth inhibition of the pathogen. Additionally, we found a group of highly aggressive strains, which completely eliminated other B. subtilis strains in the two-strain mixtures. Overall, this work shows that intraspecies interactions between B. subtilis strains can significantly alter the probiotic effect against S. Typhimurium, which is of great importance for future research on the development of multi-strain probiotics.

Human tetraspanin CD81 facilitates invasion of Salmonella enterica into human epithelial cells

Human CD81 and CD9 are members of the tetraspanin family of proteins characterized by a canonical structure of four transmembrane domains and two extracellular loop domains. Tetraspanins are known as molecular facilitators, which assemble and organize cell surface receptors and partner molecules forming clusters known as tetraspanin-enriched microdomains. They have been implicated to play various biological roles including an involvement in infections with microbial pathogens. Here, we demonstrate an important role of CD81 for the invasion of epithelial cells by Salmonella enterica. We show that the overexpression of CD81 in HepG2 cells enhances invasion of various typhoidal and non-typhoidal Salmonella serovars. Deletion of CD81 by CRISPR/Cas9 in intestinal epithelial cells (C2BBe1 and HT29-MTX-E12) reduces S. Typhimurium invasion. In addition, the effect of human CD81 is species-specific as only human but not rat CD81 facilitates Salmonella invasion. Finally, immunofluorescence microscopy and proximity ligation assay revealed that both human tetraspanins CD81 and CD9 are recruited to the entry site of S. Typhimurium during invasion but not during adhesion to the host cell surface. Overall, we demonstrate that the human tetraspanin CD81 facilitates Salmonella invasion into epithelial host cells.

Leishmaniasis in Greece: Prospects of transitioning to a One Health surveillance system

Leishmaniasis is a high burden neglected disease in the Mediterranean ecoregion, lacking surveillance attention. We aimed to provide an overview of the state of leishmaniasis surveillance in Greece, investigating the prospect of transitioning to a One Health surveillance system. We conducted a narrative review describing human and animal leishmaniasis data from Greece, including entomological findings. Through a separate review process, we describe the current leishmaniasis surveillance system pertaining to humans, animals, vectors and the environment. Additionally, we distributed likert-scale questionnaires to key informants, capturing expert-view on the necessity, existing levels and barriers of OH leishmaniasis surveillance in Greece. We identified key system strengths, weaknesses, opportunities and threats respective to a OH transition through SWOT analysis. Greece is endemic for zoonotic visceral leishmaniasis (VL) and canine leishmaniasis (CanL), displaying an increasing VL trend in recent years and high national Leishmania seroprevalence rates in dogs (range: 13.8-23.4 %). Mandatory leishmaniasis notification in humans and animals, human case-based investigations, and active case finding activities in stray dogs, comprise valuable system components of high OH operational relevance. Conversely, the existing CanL surveillance governance and the lack of systematic entomological surveillance constitute important drawbacks. Moreover, the current context of public health and animal health financial constraints in Greece may impede a strategic OH transition in leishmaniasis surveillance. On the contrary, Greece's OH experience in West Nile Virus surveillance in conjunction with leishmaniasis-expert consensus on the necessity of OH surveillance and key barriers to its realization, compose important transition opportunities. Despite shortfalls in human, animal and vector surveillance, existing system characteristics, structures and practices comprise a promising basis for developing OH cross-sectoral leishmaniasis surveillance activities in Greece.

Systematic Review of the Occurrence and Antimicrobial Resistance Profile of Foodborne Pathogens from Enterobacteriaceae in Wild Ungulates Within the European Countries

Game meat is derived from non-domesticated, free-ranging wild animals and plays an important role in human nutrition, but it is recognized as a source of food-borne and drug-resistant pathogens impacting food safety. The present review aimed to provide a comprehensive analysis of the frequency of isolation and antimicrobial resistance (AMR) profiles of major foodborne pathogens from the Enterobacteriaceae, including Salmonella, Escherichia, and Yersinia genera, in wild ungulates, across Europe in the 21st century. A systematic search was conducted via the Google Scholar database using the PRISMA guidelines. In this regard, the content of a total of 52 relevant scientific publications from both European Union (n = 10) and non-European Union countries (n = 3) was processed, highlighting the main scientific achievements and indicating knowledge gaps and future perspectives. The studies highlighted that Salmonella spp. was the most commonly encountered pathogen, and significant AMR levels were noticed for the isolated strains, especially against penicillin (32.8%) and amoxicillin (32.1%). This review underscores the importance of monitoring the presence of food-borne pathogens and their AMR in wildlife as important public health and food safety concerns.

Hydrolysis probe assays for the detection of pathogenic Enterohemorrhagic Escherichia coli: Multi-Country validation study

Enterohemorrhagic Escherichia coli (EHEC) strains are foodborne pathogens frequently associated with outbreaks linked to red meat, posing significant global food safety concerns. While several commercial assays exist for detecting EHEC strains belonging to serogroups O26, O103, O111, and O121, they often fail to distinguish pathogenic strains from non-pathogenic strains lacking virulence genes. These non-pathogenic E. coli interfere with the accuracy of existing assays, resulting in false-positives rates between 81 - 100 % for beef products. This study aimed to standardize and validate four hydrolysis probe assays for the specific detection of pathogenic strains of E. coli O26, O103, O111, and O121. Primers and probes were designed to target single nucleotide polymorphisms conserved among pathogenic strains of each target serogroup. The standardized assays were validated using a comprehensive collection of pure culture and DNA samples (n = 248) from Canada, France, Switzerland, and the United States; laboratory-inoculated beef and spinach (n = 132), fractionally inoculated ground beef (n = 390), and samples from the federal red meat surveillance program (n = 166). The results demonstrated an overall accuracy of 94.8 % in predicting the virulence profile of pure culture strains. These four assays are a single-step PCR screening tool that can determine the presence of virulent strains. These assays provide food testing laboratories worldwide with a set of reliable methods for identifying pathogenic O26, O103, O111, and O121 strains. Thus, this assay will help to reduce product waste and financial losses caused by misleading positive results caused by presence of non-pathogenic strains.

Comparative Analysis of Quantitative Methods for Campylobacter spp. Quantification: ISO 10272-2:2017, Tempo® and Real-Time PCR in Refrigerated and Frozen Turkey Cuts

New technologies for more effective microbiological assays are being adopted by the food industry to intervene more rapidly in its production chain. The aim of this study was to evaluate the alternative methods of TEMPO® CAM and real-time PCR (rtPCR) Biotecon® in comparison with the ISO 10272-2:2017 reference method for Campylobacter spp. quantification in turkey meat, aiming to validate a quick and easily replicable method in these meat matrices. A total of 416 samples were analyzed over a one-year period. The TEMPO® methodology showed inadequate performance with a significant difference (p < 0.05) compared with the reference methodology; therefore, its use was not recommended for turkey meat matrices. However, the performance of the rtPCR Biotecon® methodology showed adequate performance with no significant difference (p > 0.05), and its use was recommended in turkey meat matrices. The study was limited to exclusive research in turkey meat matrices, and expansion of the research into other matrices is recommended to verify whether the behavior of alternative methodologies is similar. The findings of this study illustrate the necessity for a thorough and comprehensive evaluation during the implementation of alternative methodologies that may potentially supplant conventional approaches.

Isolation and characterization of Yersinia phage fMtkYen3-01

Yersinia enterocolitica causes yersiniosis, the third most common gastrointestinal infection in humans throughout Europe. The emergence of multidrug resistance and the lack of effective new antibiotics have drawn attention to phage therapy as a treatment option. Here, we report the complete genome sequence of phage fMtkYen3-01, which infects Y. enterocolitica serotype O:3 strains. This phage has a genome 40,415 bp in length with 45.1% GC content and 49 predicted genes. fMtkYen3-01 infected 9.5% of the 42 Y. enterocolitica strains tested and showed stability at 25-40 °C, as well as pH 5.0-10.0. These results suggest the therapeutic potential of this phage.

High density genomic surveillance and risk profiling of clinical Listeria monocytogenes subtypes in Germany

BACKGROUND

Foodborne infections such as listeriosis caused by the bacterium Listeria monocytogenes represent a significant public health concern, particularly when outbreaks affect many individuals over prolonged time. Systematic collection of pathogen isolates from infected patients, whole genome sequencing (WGS) and phylogenetic analyses allow recognition and termination of outbreaks after source identification and risk profiling of abundant lineages.

METHODS

We here present a multi-dimensional analysis of > 1800 genome sequences from clinical L. monocytogenes isolates collected in Germany between 2018 and 2021. Different WGS-based subtyping methods were used to determine the population structure with its main phylogenetic sublineages as well as for identification of disease clusters. Clinical frequencies of materno-foetal and brain infections and in vitro infection experiments were used for risk profiling of the most abundant sublineages. These sublineages and large disease clusters were further characterised in terms of their genetic and epidemiological properties.

RESULTS

The collected isolates covered 62% of all notified cases and belonged to 188 infection clusters. Forty-two percent of these clusters were active for > 12 months, 60% generated cases cross-regionally, including 11 multinational clusters. Thirty-seven percent of the clusters were caused by sequence type (ST) ST6, ST8 and ST1 clones. ST1 was identified as hyper- and ST8, ST14, ST29 as well as ST155 as hypovirulent, while ST6 had average virulence potential. Inactivating mutations were found in several virulence and house-keeping genes, particularly in hypovirulent STs.

CONCLUSIONS

Our work presents an in-depth analysis of the genomic characteristics of L. monocytogenes isolates that cause disease in Germany. It supports prioritisation of disease clusters for epidemiological investigations and reinforces the need to analyse the mechanisms underlying hyper- and hypovirulence.

Listeria monocytogenes in the seafood industry: Exploring contamination sources, outbreaks, antibiotic susceptibility and genetic diversity

Fish and seafood are rich sources of protein, vitamins, and minerals, significantly contributing to individual health. A global increase in consumption has been observed. Listeria monocytogenes is a known problem in food processing environments and is found in various seafood forms, including raw, smoked, salted, and ready-to-eat. Without heat treatment and given L. monocytogenes' ability to multiply under refrigerated conditions, consuming seafood poses a substantial health hazard, particularly to immunocompromised individuals. Numerous global outbreaks of listeriosis have been linked to various fish products, underscoring the importance of studying L. monocytogenes. Different strains exhibit varying disease-causing abilities, making it crucial to understand and monitor the organism's virulence and resistance aspects for food safety. This paper aims to highlight the genetic diversity of L. monocytogenes found in fish products globally and to enhance understanding of contamination routes from raw fish to the final product.

Campylobacter control strategies at postharvest level

Campylobacter is highly associated with poultry and frequently causes foodborne illness worldwide. Thus, effective control measures are necessary to reduce or prevent human infections. In this review, Campylobacter control methods applicable at postharvest level for poultry meat during production, storage, and preparation are discussed. Drying and temperature are discussed as general strategies. Traditional strategies such as steaming, freezing, sanitizing, organic acid treatment, and ultraviolet light treatment are also discussed. Recent advances in nanotechnology using antibacterial nanoparticles and natural antimicrobial agents from plants and food byproducts are also discussed. Although advances have been made and there are various methods for preventing Campylobacter contamination, it is still challenging to prevent Campylobacter contamination in raw poultry meats with current methods. In addition, some studies have shown that large strain-to-strain variation in susceptibility to these methods exists. Therefore, more effective methods or approaches need to be developed to substantially reduce human infections caused by Campylobacter.

In Vitro Utilization of Prebiotics by Listeria monocytogenes

Listeria monocytognes is an emerging pathogen responsible for the serious foodborne disease, listeriosis. The commensal gut microbiota is the first line of defense against pathogen internalization. The gut microbiome can be modified by prebiotic substrates, which are frequently added to food products and dietary supplements. Prebiotics should selectively support the growth of beneficial microbes and thus improve host health. Nevertheless, little is known about their effect on the growth of L. monocytogenes. The aim of this study was to evaluate the growth ability of four L. monocytogenes strains, representing the most common serotypes, on prebiotic oligosaccharides (beta-(1,3)-D-glucan, inulin, fructooligosaccharides, galactooligosaccharides, lactulose, raffinose, stachyose and 2'-fucosyllactose and a mixture of human milk oligosaccharides) as a sole carbon source. The results showed that only beta-(1,3)-D-glucan was metabolized by L. monocytogenes. These cell culture data suggest that beta-(1,3)-D-glucan may not be selectively utilized by healthy commensal bacteria, and its role in intestinal pathogen growth warrants further exploration in vivo.

Detection of Gastrointestinal Pathogens with Zoonotic Potential in Horses Used in Free-Riding Activities during a Countrywide Study in Greece

The objectives of this study were (a) to detect zoonotic gastrointestinal pathogens in faecal samples of horses using the FilmArray® GI Panel and (b) to identify variables potentially associated with their presence. Faecal samples collected from 224 horses obtained during a countrywide study in Greece were tested by means of the BioFire® FilmArray® Gastrointestinal (GI) Panel, which uses multiplex-PCR technology for the detection of 22 pathogens. Gastrointestinal pathogens were detected in the faecal samples obtained from 97 horses (43.3%). Zoonotic pathogens were detected more frequently in samples from horses in courtyard housing (56.0%) than in samples from horses in other housing types (39.7%) (p = 0.040). The most frequently detected zoonotic pathogens were enteropathogenic Escherichia coli (19.2% of horses) and Shiga-like toxin-producing E. coli stx1/stx2 (13.8%). During multivariable analysis, two variables emerged as significant predictors for the outcome 'detection of at least one zoonotic pathogen in the faecal sample from an animal': (a) the decreasing age of horses (p = 0.0001) and (b) the presence of livestock at the same premises as the horses (p = 0.013). As a significant predictor for the outcome 'detection of two zoonotic pathogens concurrently in the faecal sample from an animal', only the season of sampling of animals (autumn) emerged as significant in the multivariable analysis (p = 0.049). The results indicated a diversity of gastrointestinal pathogens with zoonotic potential in horses and provided evidence for predictors for the infections; also, they can serve to inform horse owners and handlers regarding the possible risk of transmission of pathogens with zoonotic potential. In addition, our findings highlight the importance of continuous surveillance for zoonotic pathogens in domestic animals.

Systematic risk ranking of microbiological hazards in infant foods

Ensuring food safety, particularly for vulnerable groups, like infants and young children, requires identifying and prioritizing potential hazards in food chains. We previously developed a web-based decision support system (DSS) to identify specific microbiological hazards (MHs) in infant and toddler foods through a structured five-step process. This study takes the framework further by introducing systematic risk ranking (RR) steps to rank MH risks with seven criteria: process survival, recontamination, growth opportunity, meal preparation, hazard-food association evidence, food consumption habits of infants and toddlers in the EU, and MH severity. Each criterion is given a semi-quantitative or quantitative score or risk value, contributing to the final MH risk calculation via three aggregation methods: semi-quantitative risk scoring, semi-quantitative risk value, and outranking multi-criteria decision analysis (MCDA). To validate the criteria and ranking approaches, we conducted a case study to rank MH risks in infant formula, compared the results of the three risk ranking methods, and additionally evaluated the ranking results against expert opinions to ensure their accuracy. The results showed strong agreement among the three methods, consistently ranking Salmonella non-Typhi and Cronobacter spp. and Shiga-toxin-producing Escherichia coli as the top MH risks in infant formulae, with minor deviations. When MHs were ranked after an initial hazard identification step, all three methods produced nearly identical MH rankings, reinforcing the reliability of the ranking steps and the selected criteria. Notably, the risk value and MCDA methods provided more informative MH rankings compared to the risk scoring method. The risk value and risk scoring methods were implemented into an online tool, called the MIcrobiological hazards risk RAnking decision support system (Mira-DSS), available at https://foodmicrobiologywur.shinyapps.io/MIcrobial_hazards_RAnking/. In conclusion, our framework enables the ranking of MH risks, facilitating intervention comparisons and resource allocations to mitigate MH risks in infant foods, with potential applicability to broader food categories.

Occurrence and antimicrobial resistance of Salmonella isolates in farrow-to-finish pig farms in Bulgaria

Salmonella spp. is an important zoonotic and foodborne pathogen. It is spread worldwide and represents a public health risk. Pigs are a significant reservoir and are frequently subclinical carriers. The aim of this study was to detect the occurrence and antimicrobial resistance of Salmonella isolates being the five most important for public health Salmonella serovars in fattening pigs in Bulgaria. The isolation of Salmonella spp. was carried out according to EN ISO 6579-1 for the detection of Salmonella bacteria in feces and Salmonella serotyping following the Kauffmann-White scheme. All confirmed S. enterica isolates were analysed by the disk-diffusion method for susceptibility to 14 antimicrobials. Salmonella enterica was detected in 13 out of 32 tested farms in Bulgaria. The overall percentage of Salmonella positive pooled fecal samples was 6.8% (43 of 630 samples). The highest occurrence was present in fattening pigs aged between 121-180 days (16.3%; 20/123), followed by dry sows (6.5%; 4/62) and gilts (4.8%; 12/248). About 75% of the isolated strains belonged to three serotypes: Salmonella Infantis (41.9%), Salmonella Give (16.3%) and Salmonella Typhimurium monophasic (16.3%). All the tested isolates were resistant to Tilmicosin (100%), 88.4% to Ampicillin, followed by 69.8% to Tiamulin, 25.6% to Amoxicillin and Chlortetracycline. Multidrug resistance was recorded in 62.8 % of the tested strains. This study reports data regarding the circulation of the most important for public health five Salmonella serovars (S. Enteritidis, S. Typhimurium, S. Typhimurium monophasic, S. Infantis and S. Derby) in farrow-to-finish pig farms in Bulgaria and represent 74.4% of the total Salmonella spp. isolates. This phenomenon has critical effects for the health of consumers and therefore represents a key "one health" issue.

Health Hazard Associated with the Presence of Clostridium Bacteria in Food Products

Clostridium bacteria were already known to Hippocrates many years before Christ. The name of the Clostridium species is owed to the Polish microbiologist, Adam Prażmowski. It is now known that these Clostridium bacteria are widespread in the natural environment, and their presence in food products is a threat to human health and life. According to European Food Safety Authority (EFSA) reports, every year, there are poisonings or deaths due to ingestion of bacterial toxins, including those of the Clostridium spp. The strengthening of consumer health awareness has increased interest in consuming products with minimal processing in recent years, which has led to a need to develop new techniques to ensure the safety of microbiological food, including elimination of bacteria from the Clostridium genera. On the other hand, the high biochemical activity of Clostridium bacteria allows them to be used in the chemical, pharmaceutical, and medical industries. Awareness of microbiological food safety is very important for our health. Unfortunately, in 2022, an increase in infections with Clostridium bacteria found in food was recorded. Knowledge about food contamination should thus be widely disseminated.

Genetic diversity of Listeria monocytogenes from seafood products, its processing environment, and clinical origin in the Western Cape, South Africa using whole genome sequencing

Listeria monocytogenes is a concern in seafood and its food processing environment (FPE). Several outbreaks globally have been linked to various types of seafood. Genetic profiling of L. monocytogenes is valuable to track bacterial contamination throughout the FPE and in understanding persistence mechanisms, with limited studies from South Africa. Forty-six L. monocytogenes isolates from origins: Fish/seafood products (n = 32) (salmon, smoked trout, fresh hake, oysters), the FPE (n = 6), and clinical (n = 8) were included in this study. Lineage typing, antibiotic susceptibility testing, and screening for two genes (bcrABC and emrC) conferring sanitizer tolerance was conducted. The seafood and FPE isolates originated from seven different factories processing various seafood products with undetermined origin. All clinical isolates were categorized as lineage I, and seafood and FPE isolates were mostly categorized into lineage II (p < 0.01). Seafood and FPE isolates (53%) carried the bcrABC gene cassette and one fish isolate, the emrC gene. A subset, n = 24, was grouped into serotypes, sequence types (STs), and clonal complexes (CCs) with whole genome sequencing (WGS). Eight CCs and ten STs were identified. All clinical isolates belonged to serogroup 4b, hypervirulent CC1. CC121 was the most prevalent in isolates from food and the FPE. All isolates carried Listeria pathogenicity islands (LIPI) 1 and 2. LIPI-3 and LIPI-4 were found in certain isolates. We identified genetic determinants linked to enhanced survival in the FPE, including stress survival islets (SSI) and genes conferring tolerance to sanitizers. SSI-1 was found in 44% isolates from seafood and the FPE. SSI-2 was found in all the ST121 seafood isolates. Isolates (42%) harbored transposon Tn1688_qac (ermC), conferring tolerance to quaternary ammonium compounds. Five plasmids were identified in 13 isolates from seafood and the FPE. This is the first One Health study reporting on L. monocytogenes genetic diversity, virulence and resistance profiles from various types of seafood and its FPE in South Africa.

First Data on WGS-Based Typing and Antimicrobial Resistance of Human Salmonella Enteritidis Isolates in Greece

Salmonella enterica subsp. enterica serotype Enteritidis (S. Enteritidis) is one of the major causes of foodborne infections and is responsible for many national and multi-country foodborne outbreaks worldwide. In Greece, human salmonellosis is a mandatory notifiable disease, with laboratory surveillance being on a voluntary basis. This study aims to provide the first insights into the genetic characteristics and antimicrobial resistance profiles of 47 S. Enteritidis human isolates using whole-genome sequencing (WGS) technology. The S. Enteritidis population was mainly resistant to fluoroquinolones due to gyrA point mutations, whereas one isolate presented a multi-resistant plasmid-mediated phenotype. ST11 was the most frequent sequence type, and phylogenetic analysis through the cgMLST and SNP methods revealed considerable genetic diversity. Regarding virulence factors, 8 out of the 24 known SPIs and C63PI were detected. Due to the observed variability between countries, it is of utmost importance to record the circulating S. Enteritidis strains' structure and genomic epidemiology at the national level. WGS is a valuable tool that is revolutionizing our approach to Salmonella by providing a deeper understanding of these pathogens and their impact on human health.

A current insight into Salmonella's inducible acid resistance

Salmonella is a diverse and ubiquitous group of bacteria and a major zoonotic pathogen implicated in several foodborne disease outbreaks worldwide. With more than 2500 distinct serotypes, this pathogen has evolved to survive in a wide spectrum of environments and across multiple hosts. The primary and most common source of transmission is through contaminated food or water. Although the main sources have been primarily linked to animal-related food products, outbreaks due to the consumption of contaminated plant-related food products have increased in the last few years. The perceived ability of Salmonella to trigger defensive mechanisms following pre-exposure to sublethal acid conditions, namely acid adaptation, has renewed a decade-long attention. The impact of acid adaptation on the subsequent resistance against lethal factors of the same or multiple stresses has been underscored by multiple studies. Α plethora of studies have been published, aiming to outline the factors that- alone or in combination- can impact this phenomenon and to unravel the complex networking mechanisms underlying its induction. This review aims to provide a current and updated insight into the factors and mechanisms that rule this phenomenon.

Salmonella in Chicken and Pork Meat as a Likely Major Contributor to Foodborne Illness in Peru

Nontyphoidal Salmonella is one of the major causes of self-limiting diarrheal disease and the most common foodborne pathogen worldwide. It is an important contributor to the burden of foodborne illness in South America, including Peru, where chicken and pork are important vehicles for Salmonella infection. Salmonella infections are underreported, particularly in low- and middle-income countries where concerted action tackling Salmonella along the chicken and pork chains, from primary production to retail, is urgently needed. To support and inform the implementation of new strategies to reduce Salmonella contamination of chicken and pork, this study describes the frequency and distribution of foodborne outbreaks attributed to Salmonella in Peru and evaluates the level of Salmonella in chicken and pork meat sold in markets of three regions of Peru. To that end, we analyzed historical reports of foodborne outbreaks, levels of Salmonella in chicken and pork sold in markets, and the number of mesophiles in the collected meat samples. As a result, the microbiological analysis reveals a widespread contamination of chicken (77.1%) and pork (26.8%) with Salmonella. It also pinpoints Salmonella as the causative agent in nearly half of the outbreaks (47.0%) where the potential origin is identified over a 11-year period with chicken, mayonnaise, and pork being the most likely food vehicles. These results suggest that Salmonella is a major contributor to foodborne illness in Peru and that the monitoring of mesophiles could be a good strategy for surveillance, generating data to support source attribution studies and ultimately evidence-informed policies.

Clinical Outcome and Factors with Dietary Behaviors in Pregnant Women with Listeria monocytogenes: A Hospital-Based Case-Control Study in Shanghai

Listeriosis is a globally rare foodborne disease that causes fetal-placental infection, leading to adverse pregnancy outcome, while limited research among pregnant women is available in China. This study was therefore aimed at analyzing the incidence, clinical manifestations, and clinical outcome of listeriosis among pregnant women and its associated dietary behavior risk factors in prevention. A hospital-based case-control study had been conducted from January 2017 to December 2021. Clinical data, laboratory information, and questionnaires including dietary behaviors and personal hygiene were collected within 2 days after case diagnosis. There were 48 pregnant women, including 12 cases and 36 controls, with an average age of 31.19 ± 3.75 years. The incidence of admission-based listeriosis among pregnant women was 1.6058 per 10,000. The 12 strains were divided into 3 serotypes: 1/2a(83.33%), 1/2b(8.33%), and 4b(8.33%). Among the cases, 5 cases (41.67%) resulted in abortion, 3 cases (25%) induced preterm labor, and 4 cases (33.33%) had full-term deliveries after treatment. There were 7 live births in the case group, among which 6 were admitted to the neonatal intensive care unit (NICU), while 1 case had a healthy fetal outcome. All patients in the control group gave birth to live fetuses. Epidemiological investigation revealed that pregnant women dining at restaurants three or more times per week might increase the risk of having Listeria infection. There were no significant differences in dietary consumed behaviors, hand hygiene, and refrigerator usage behaviors between case and control groups. The study suggested that dining at restaurants might be associated with Listeria infection among pregnant women. Therefore, it is essential to enhance education on listeriosis serious consequences and promote healthy dietary and hygiene habits among pregnant women.

Prevalence, serotype, antimicrobial susceptibility, contamination factors, and control methods of Salmonella spp. in retail fresh fruits and vegetables: A systematic review and meta-analysis

This research presents a comprehensive review of Salmonella presence in retail fresh fruits and vegetables from 2010 to 2023, utilizing data from recognized sources such as PubMed, Scopus, and Web of Science. The study incorporates a meta-analysis of prevalence, serovar distribution, antimicrobial susceptibility, and antimicrobial resistance genes (ARGs). Additionally, it scrutinizes the heterogeneous sources across various food categories and geographical regions The findings show a pooled prevalence of 2.90% (95% CI: 0.0180-0.0430), with an increase from 4.63% in 2010 to 5.32% in 2022. Dominant serovars include S. Typhimurium (29.14%, 95% CI: 0.0202-0.6571) and S. Enteritidis (21.06%, 95% CI: 0.0181-0.4872). High resistance rates were noted for antimicrobials like erythromycin (60.70%, 95% CI: 0.0000-1.0000) and amoxicillin (39.92%, 95% CI: 0.0589-0.8020). The most prevalent ARGs were blaTEM (80.23%, 95% CI: 0.5736-0.9692) and parC mutation (66.67%, 95% CI: 0.3213-0.9429). Factors such as pH, water activity, and nutrient content, along with external factors like the quality of irrigation water and prevailing climatic conditions, have significant implications on Salmonella contamination. Nonthermal sterilization technologies, encompassing chlorine dioxide, ozone, and ultraviolet light, are emphasized as efficacious measures to control Salmonella. This review stresses the imperative need to bolster prevention strategies and control measures against Salmonella in retail fresh fruits and vegetables to alleviate related food safety risks.

Brucella spp. in Wildlife of the Lombardy Region, Northern Italy

Surveillance data collected in the period 2017-20 for Brucella spp. in wildlife of the Lombardy Region in northern Italy were used to describe the exposure of the wildlife species to Brucella spp. in wild boar (Sus scrofa), European brown hare (Lepus europaeus), fallow deer (Dama dama), red deer (Cervus elaphus), and roe deer (Capreolus capreolus). Among the tested species, wild boar (n=6,440) showed the highest percentage of seropositive samples (5.9%). Notably, wild boars of perifluvial area of the Po River showed higher percentages of positivity than those of the pre-Alpine district. In addition, during the hunting season in 2018, 95 organs (uterus or testes, spleen, and submandibular lymph nodes) from wild boar of the perifluvial area of the Po River were collected for bacteriological examination. Brucella suis was isolated in culture from 18.9% of tested lymph nodes. These serological and microbiological results highlight the presence of B. suis in wild boar and suggest the importance of wild boar as a reservoir for B. suis. Comparison of the spatial distribution of Brucella-seropositive wild boars with the location of backyard swine farms revealed a higher chance of contact between the two populations only in the areas where the lower percentage of seropositive samples was observed. Conversely, the high percentage of seropositive samples observed in the Po River area coupled with positive microbiological cultures suggest a greater risk of infection for the humans directly or indirectly involved in wild boar hunting activity. These results may serve as a basis to establish sound wildlife management and to adopt education campaigns aimed at reducing the risk of human infection in people involved in wild boar hunting related activities.

In vitro investigations on interference of selected probiotic candidates with Campylobacter jejuni adhesion and invasion of primary chicken derived cecal and Caco-2 cells

BACKGROUND

Campylobacter (C.) jejuni is one of the most important bacterial foodborne pathogens worldwide. Probiotics such as Lactobacillus or Bacillus species are considered one option for reducing the colonization rate and magnitude in poultry, the most frequent source of human infections. Due to the lack of suitable avian in vitro models such as chicken intestinal cell lines, especially those derived from the cecum, most in vitro studies on C. jejuni host interaction have been conducted with human intestinal cell lines. In this study, we compared C. jejuni-cell interactions between primary chicken cecal cells and the human intestinal cell line Caco-2, which is derived from colorectal adenocarcinoma, and investigated possible interfering effects of selected probiotic candidates.

RESULTS

We detected differences in adhesion and invasion between the two tested gut cell types and between different C. jejuni strains. The probiotic inhibition of C. jejuni adhesion and invasion of human and avian gut cells was affected by host cell type, investigated C. jejuni strain and time points of probiotic treatment. Additionally, our results suggest a possible correlation between C. jejuni invasion and the detected increase in IL-6 mRNA expression.

CONCLUSIONS

Our results indicate distinct differences between avian and human gut cells in their interaction with C. jejuni. Therefore, data obtained in one host species on C. jejuni-host interaction may not easily be transferrable to another one. The factors influencing the variable efficacy of probiotic intervention in chicken and human derived cells should be investigated further.

A trans-acting sRNA SaaS targeting hilD, cheA and csgA to inhibit biofilm formation of S. Enteritidis

INTRODUCTION

Salmonella Enteritidis has brought great harm to public health, animal production and food safety worldwide. The biofilm formed by Salmonella Enteritidis plays a critical role in microbial cross-contamination. Small non-coding RNAs (sRNAs) have been demonstrated to be responsible for regulating the formation of biofilm. The sRNA SaaS has been identified previously, that promotes pathogenicity by regulating invasion and virulence factors. However, whether the SaaS is implicated in regulating biofilm formation in abiotic surfaces remains unclear.

OBJECTIVES

This study aimed to clarify the effect of SaaS in Salmonella Enteritidis and explore the modulatory mechanism on the biofilm formation.

METHODS

Motility characteristics and total biomass of biofilm of test strains were investigated by the phenotypes in three soft agar plates and crystal violet staining in polystyrene microplates. Studies of microscopic structure and extracellular polymeric substances (EPS) of biofilm on solid surfaces were carried out using confocal laser scanning microscope (CLSM) and Raman spectra. Transcriptomics and proteomics were applied to analyze the changes of gene expression and EPS component. The RNA-protein pull-down and promoter-reporter β-galactosidase activity assays were employed to analyze RNA binding proteins and identify target mRNAs, respectively.

RESULTS

SaaS inhibits biofilm formation by repressing the adhesion potential and the secretion of EPS components. Integration of transcriptomics and proteomics analysis revealed that SaaS strengthened the expression of the flagellar synthesis system and downregulated the expression of curli amyloid fibers. Furthermore, RNA-protein pull-down interactome datasets indicated that SaaS binds to Hfq (an RNA molecular chaperone protein, known as a host factor for phage Qbeta RNA replication) uniquely among 193 candidate proteins, and promoter-reporter β-galactosidase activity assay confirmed target mRNAs including hilD, cheA, and csgA.

CONCLUSION

SaaS inhibits the properties of bacterial mobility, perturbs the secretion of EPS, and contributes to the inhibition of biofilm formation by interacting with target mRNA (hilD, cheA, and csgA) through the Hfq-mediated pathway.

Genotypic and phenotypic analysis of Salmonella enterica serovar Derby, looking for clues explaining the impairment of egg isolates to cause human disease

Salmonella enterica serovar Derby causes foodborne disease (FBD) outbreaks worldwide, mainly from contaminated pork but also from chickens. During a major epidemic of FBD in Uruguay due to S. enteritidis from poultry, we conducted a large survey of commercially available eggs, where we isolated many S. enteritidis strains but surprisingly also a much larger number (ratio 5:1) of S. Derby strains. No single case of S. Derby infection was detected in that period, suggesting that the S. Derby egg strains were impaired for human infection. We sequenced fourteen of these egg isolates, as well as fifteen isolates from pork or human infection that were isolated in Uruguay before and after that period, and all sequenced strains had the same sequence type (ST40). Phylogenomic analysis was conducted using more than 3,500 genomes from the same sequence type (ST), revealing that Uruguayan isolates clustered into four distantly related lineages. Population structure analysis (BAPS) suggested the division of the analyzed genomes into nine different BAPS1 groups, with Uruguayan strains clustering within four of them. All egg isolates clustered together as a monophyletic group and showed differences in gene content with the strains in the other clusters. Differences included variations in the composition of mobile genetic elements, such as plasmids, insertion sequences, transposons, and phages, between egg isolates and human/pork isolates. Egg isolates showed an acid susceptibility phenotype, reduced ability to reach the intestine after oral inoculation of mice, and reduced induction of SPI-2 ssaG gene, compared to human isolates from other monophyletic groups. Mice challenge experiments showed that mice infected intraperitoneally with human/pork isolates died between 1-7 days p.i., while all animals infected with the egg strain survived the challenge. Altogether, our results suggest that loss of genes functions, the insertion of phages and the absence of plasmids in egg isolates may explain why these S. Derby were not capable of producing human infection despite being at that time, the main serovar recovered from eggs countrywide.

Tularemia on the rise in Switzerland? A one health approach is needed!

In the last 10 years, an increase in tularemia cases has been observed in both humans and animals in Switzerland. In these, infection with Francisella tularensis, the causative agent of the zoonotic disease tularemia, can occur through arthropod vectors or contact to infected animals or exposure to contaminated environmental sources. Currently, we are only able to postulate potential aetiologies: (i) behavioral changes of humans with more exposure to endemic habitats of infected arthropod vectors; (ii) an increased rate of tularemia infected ticks; (iii) increasing number and geographical regions of tick biotopes; (iv) increasing and/or more diverse reservoir populations; (v) increasing presence of bacteria in the environment; (vi) raised awareness and increased testing among physicians; (vii) improved laboratory techniques including molecular testing. To approach these questions, a one-health strategy is necessary. A functioning collaboration between public health, human medicine, and diagnostic and veterinary units for the control of tularemia must be established. Furthermore, the public should be included within citizen-supported-science-projects.

Seroprevalence study of brucellosis in wild boar hunted for private consumption in northeast Portugal

Brucellosis is an important infectious disease caused by bacteria of the genus Brucella. In the northeast region of Portugal, infection with Brucella melitensis is endemic in small ruminants, and there are also humans' cases. However, the epidemiological role of the wild boar in the dynamics of this disease in this region is unknown. In this study, a total of 332 blood samples were collected from wild boar hunted in thirty-six hunting areas during the 2022/2023 hunting season. All were taken by the hunters for private consumption, with no evisceration or examination in the field. Serum samples were tested by indirect ELISA (i-ELISA). It was observed that 88 wild boars were exposed to Brucella spp., pointing to a seroprevalence of 26.5% (95% CI: 21.8 - 31.3%). This high prevalence underlines the importance that wild boar may have in the dynamics of this disease in the region and its potential transmission to other animals, and to humans (for example, during the handling of carcasses). Increased awareness and knowledge of brucellosis in wild boar is essential for the implementation of effective practices and habits and, consequently, for the control and prevention of this important zoonosis.

Multidrug resistance in Salmonella isolates of swine origin: mobile genetic elements and plasmids associated with cephalosporin resistance with potential transmission to humans

The emergence of foodborne Salmonella strains carrying antimicrobial resistance (AMR) in mobile genetic elements (MGE) is a significant public health threat in a One Health context requiring continuous surveillance. Resistance to ciprofloxacin and cephalosporins is of particular concern. Since pigs are a relevant source of foodborne Salmonella for human beings, we studied transmissible AMR genes and MGE in a collection of 83 strains showing 9 different serovars and 15 patterns of multidrug resistant (MDR) previously isolated from pigs raised in the conventional breeding system of Northern Spain. All isolates were susceptible to ciprofloxacin and three isolates carried blaCMY-2 or blaCTX-M-9 genes responsible for cefotaxime resistance. Filter mating experiments showed that the two plasmids carrying blaCTX-M-9 were conjugative while that carrying blaCMY-2 was self-transmissible by transformation. Whole-genome sequencing and comparative analyses were performed on the isolates and plasmids. The IncC plasmid pSB109, carrying blaCMY-2, was similar to one found in S. Reading from cattle, indicating potential horizontal transfer between serovars and animal sources. The IncHI2 plasmids pSH102 in S. Heidelberg and pSTM45 in S. Typhimurium ST34, carrying blaCTX-M-9, shared similar backbones and two novel "complex class 1 integrons" containing different AMR and heavy metal genes. Our findings emphasize the importance of sequencing techniques to identify emerging AMR regions in conjugative and stable plasmids from livestock production. The presence of MGE carrying clinically relevant AMR genes raises public health concerns, requiring monitoring to mitigate the emergence of bacteria carrying AMR genes and subsequent spread through animals and food.IMPORTANCEThe emergence of foodborne Salmonella strains carrying antimicrobial resistance (AMR) in mobile genetic elements (MGE) is a significant public health threat in a One Health context. Since pigs are a relevant source of foodborne Salmonella for humans, in this study, we investigate different aspects of AMR in a collection of 83 Salmonella showing nine different serovars and 15 patterns of multidrug resistant (MDR) isolated from pigs raised in the conventional breeding system. Our findings emphasize the importance of sequencing techniques to identify emerging AMR regions in conjugative and stable plasmids from livestock production. The presence of MGE carrying clinically relevant AMR genes raises public health concerns, requiring monitoring to mitigate the emergence of bacteria carrying AMR genes and subsequent spread through animals and food.

Fighting Salmonella Infantis: bacteriophage-driven cleaning and disinfection strategies for broiler farms

Introduction

Salmonella is a bacterium that can cause food-borne infections and is responsible for the most common gastrointestinal illnesses. The emergence of multi-drug resistant (MDR) strains worldwide is a major threat, representing a major challenge in public health. To reduce its incidence, the One Health approach is required, and the development of new biocontrol protocols will help prevent or eliminate the spread of Salmonella. Prevention measures, such as on-farm cleaning and disinfection protocols, are a crucial step in reducing infection to new flocks and eliminating bacteria that remain in the facilities. However, MDR Salmonella species, such as S. Infantis, are highly resistant to conventional cleaning and disinfection protocols, with an increased ability to persist in the broiler farm environment. The need for alternative biocontrol methods has led to the use of bacteriophages or phages, viruses that target bacteria, as promising tools. Thus, the aim of this study was to evaluate the efficacy of phages as a biocide against S. Infantis isolates in combination with cleaning and disinfection protocols in 10 commercial poultry farms.

Methods

All commercial farms selected in this study had persistent Salmonella, even after the routinely used cleaning and disinfection procedures. In addition, Salmonella isolated before treatment were phenotypically characterized by antimicrobial resistance patterns.

Results

The results showed that 100% of S. Infantis were resistant to at least one antibiotic, and > 70% were MDR. Phages were then isolated against the in-farm bacteria, purified, and multiplied for each poultry farm. The cleaning and disinfection protocols included the application of the lytic phages (vB_Si_CECAV_FGS009; vB_Si_CECAV_FGS017; vB_Si_CECAV_FGS029 and vB_Si_CECAV _FGS030) twice at 24-h intervals between cleaning and disinfection. Following the cleaning and disinfection procedures, Salmonella detection was reduced from 100% after cleaning to 36% after applying the phages and dropped to 0% after the final step of disinfection, thus eliminating Salmonella from the farm facilities.

Discussion

This study demonstrates that bacteriophage application after cleaning and before disinfection enhances the removal of MDR Salmonella Infantis in commercial broiler farms, suggesting their use as biocontrol agents to reduce Salmonella, a major public health concern.

Salmonella Hadar linked to two distinct transmission vehicles highlights challenges to enteric disease outbreak investigations

In 2020, an outbreak of Salmonella Hadar illnesses was linked to contact with non-commercial, privately owned (backyard) poultry including live chickens, turkeys, and ducks, resulting in 848 illnesses. From late 2020 to 2021, this Salmonella Hadar strain caused an outbreak that was linked to ground turkey consumption. Core genome multilocus sequence typing (cgMLST) analysis determined that the Salmonella Hadar isolates detected during the outbreak linked to backyard poultry and the outbreak linked to ground turkey were closely related genetically (within 0-16 alleles). Epidemiological and traceback investigations were unable to determine how Salmonella Hadar detected in backyard poultry and ground turkey were linked, despite this genetic relatedness. Enhanced molecular characterization methods, such as analysis of the pangenome of Salmonella isolates, might be necessary to understand the relationship between these two outbreaks. Similarly, enhanced data collection during outbreak investigations and further research could potentially aid in determining whether these transmission vehicles are truly linked by a common source and what reservoirs exist across the poultry industries that allow Salmonella Hadar to persist. Further work combining epidemiological data collection, more detailed traceback information, and genomic analysis tools will be important for monitoring and investigating future enteric disease outbreaks.