The European Union One Health 2019 Zoonoses Report

First characterization of the resistome, virulome and genomic diversity of Salmonella enterica serovar Inganda: a rare, clinically-related and drug susceptible serovar

Non-typhoid Salmonella are among the main causes of foodborne diseases worldwide. However, information on rare serovars is scarce, limiting the understanding of their prevalence, distribution and pathogenesis. Salmonella enterica serovar Inganda (S. Inganda) is a rare non-typhoid serovar. Considering the few existing reports, and the current use of genomics, this study characterized for the first time the antimicrobial resistance, pathogenic potential and diversity of S. Inganda genomes worldwide. A S. Inganda strain from human feces in 2018 in Brazil (SI264) had its resistance determined against 18 antimicrobials by disk-diffusion and had its genome sequenced. S. Inganda publicly available genomes (n = 12) were analyzed for genotypic resistance, stress and virulence genes, plasmids, pathogenicity islands, prophages, Multi-Locus Sequence Typing (MLST), core-genome MLST (cgMLST), and single-nucleotide polymorphisms (SNPs). SI264 showed no phenotypic resistance. All 12 S. Inganda genomes harbored genes or mutations for aminoglycoside (aac(6')-Iaa), quinolone (parC Thr57→Ser), and acid (asr) resistance, multi-drug efflux systems (mdsAB), and gold tolerance (golST). One genome from US harbored pKPC-CAV1321 plasmid. Nine pathogenicity islands, 174 Salmonella virulence genes, and 17 prophages were found in different frequencies. Although a great genomic diversity was noticed, S. Inganda genomes from US and UK were closely related. In conclusion, genomic analyses were able to characterize the current available genomes of S. Inganda strains mostly as genetically diverse, susceptible to antimicrobials, and potentially acid and heavy metal resistant. The presence of numerous virulence features also suggested their pathogenic potential, especially among clinical strains, and reinforced the importance to better characterize rare non-typhoid serovars.

Risk factors associated with long-term shedding infections of non-typhoidal Salmonella in humans

PURPOSE

Non-typhoidal Salmonella (NTS) gastroenteritis in humans is typically self-limited, resolving within 48-72 h. However, some infections result in a carrier state characterised by persistent gut colonisation and long-term shedding (LTS). This study aimed to investigate risk factors associated with LTS of NTS in humans.

METHODS

Salmonellosis cases reported to the Norwegian surveillance system in 2019 were invited to participate. Participants submitted a follow-up stool sample and a questionnaire five weeks after initial sampling (detecting infection). Stool samples were cultured, and isolates were sequenced to determine genotype, serotype and antimicrobial resistance genotype. NTS cases were classified as LTS if the isolates from both samples differed by ≤ 5 alleles. Adjusted odds ratios (aORs) with 95% confidence intervals (95%CIs) were calculated using logistic regression to investigate potential risk factors associated with LTS.

RESULTS

Of 1,094 reported cases, 255 (23%) with NTS participated; 24% were classified as LTS. Children aged 0-5 years were 6.7 times more likely to exhibit LTS compared to adults aged 18-44 years (aOR = 6.71, 95%CI:1.67-26.94). Participants who received regular medication and those following a lactose-free diet were 2.2 (aOR = 2.17, 95%CI:1.02-4.64) and 7.2 (aOR = 7.24, 95%CI:1.48-35.40) times more likely to exhibit LTS than those who did not, respectively. Participants with S. Agbeni or S. Bron were 6 times more likely to exhibit LTS compared to S. Typhimurium cases (aOR = 6.29, 95%CI:1.40-28.16).

CONCLUSIONS

Observed risk factors associated with LTS included young age, regular medication use, lactose-free diet, and specific Salmonella serotypes. Further research is needed to increase knowledge regarding LTS and inform infection control measures.

Prevalence and Antimicrobial Resistance of Listeria monocytogenes Isolated from Dairy Products in Romania

Background/Objectives:Listeria monocytogenes is a significant foodborne pathogen associated with dairy products, which can pose serious public health risks, particularly for vulnerable populations. This study aimed to assess the prevalence, serotype distribution, and antimicrobial resistance profiles of Listeria monocytogenes isolated from dairy products collected in Romania over a three-year period (2021-2023). To the best of our knowledge, this is the first comprehensive study addressing these issues within the country. Methods: A total of 10,306 dairy samples, including milk, cheeses, ice cream, yogurt, and other dairy-based products, were collected and analyzed using standard microbiological methods. Molecular serotyping was performed to identify the most common serogroups. The antimicrobial susceptibility of the isolates was also conducted. Results: The overall prevalence of Listeria monocytogenes was 0.41% (43/10,306). The most frequently detected serogroup was IVb (74.41%), followed by IIa (23.25%) and IIb (2.32%). Ice cream was the most affected product, followed by fresh telemea made from cow milk. Antimicrobial susceptibility testing revealed higher resistance rates for oxacillin and trimethoprim-sulfamethoxazole (13.95% each), while all isolates were susceptible to ciprofloxacin, levofloxacin, and moxifloxacin. Conclusions: The findings emphasize the need for continuous monitoring of Listeria monocytogenes in dairy products, particularly ice cream and fresh cheeses, due to their high contamination rates. The study's results are valuable for comparative analysis with findings from other countries, helping to establish a broader understanding of Listeria monocytogenes contamination trends and resistance profiles.

Genomic characterization of Listeria monocytogenes isolated from normally sterile human body fluids in Lithuania from 2016 to 2021

Listeria monocytogenes is a saprophytic gram-positive bacterium and opportunistic foodborne pathogen that can cause listeriosis in humans. The incidence of listeriosis has been rising globally and, despite antimicrobial treatment, the mortality rates associated with the most severe forms of listeriosis such as sepsis, meningitis and meningoencephalitis remain high. The notification of listeriosis in humans is mandatory in Lithuania, and up to 20 cases are reported annually. However, no studies have described the detailed virulence and antimicrobial susceptibility profiles of any clinical L. monocytogenes strains in Lithuania. Accordingly, this study aimed to describe the antibiotic susceptibility of invasive L. monocytogenes and perform in-depth characterization of strains isolated from patients with neuroinfections through whole-genome sequencing. A total of 70 isolates were collected, mostly from infected patients aged 65 or older, between 2016 and 2021 : 41 (58.6%) from blood, 19 (27.1%) from cerebrospinal fluid, 5 (7.1%) from wounds, 1 (1.4%) from pleural fluid and 1 (1.4%) from a brain abscess. Two phylogenetic lineages were identified-I (n = 16/70, 22.9%) and II (n = 54/70, 77.1%)-along with three serogroups-IIa (n = 53/70, 75.7%), IVb (n = 16/70, 22.9%), and IIc (n = 1/70, 1.4%). Genomic analysis of 20 isolates showed a high level of diversity with seven genotypes: ST6 (n = 6), ST155 (n = 5), ST8 (n = 4), ST504 (n = 2) and singletons for ST37, ST451 and ST2. Phylogenetic analysis clustered these isolates into two clades defined by serogroups IVb and IIa. Notably, five isolates were clustered tightly together (difference of 6-48 core SNPs from reference and 0, 4 or 44 SNPs from each other) with ST155, previously reported in a European outbreak. Comparison with publicly available L. monocytogenes genomes did not identify unique clusters or genotypes. No acquired antimicrobial resistance genes were identified. Our study highlights the complementary value of whole-genome sequencing in routine PCR-based surveillance in Lithuania. This is the first study to characterize and compare genomes for L. monocytogenes associated with neuroinfections in Lithuania using whole-genome sequencing. The retrospective detection of the ST155 clone underscores the need for a review and strengthening of epidemiological surveillance strategies in clinical and non-clinical settings in Lithuania.

Zoonotic Abortifacient Agents in Bovine Abortion: Diagnostic Assessment of 125 Cases (2015-2017)

BACKGROUND

The threat of zoonotic diseases is significant to global public health. Campylobacter spp., Coxiella burnetii (C. burnetii), Brucella spp., Listeria monocytogenes (L. monocytogenes), Chlamydia abortus (C. abortus), and Cache Valley virus (CVV) play a role in bovine abortion and are transmitted from animals to humans.

OBJECTIVE

This study aimed to investigate the presence of these zoonotic abortifacient agents in bovine foetuses (n = 125), each from different herds, in a three-year period in Türkiye.

METHODS

The detection and differentiation of Brucella spp. was achieved using a PCR method, while a multiplex PCR assay was used to detect and differentiate Campylobacter spp. Real-time PCR assays were used to detect C. burnetii, C. abortus, and L. monocytogenes. Furthermore, samples were tested for CVV using one-step duplex real-time RT-PCR.

RESULTS

Although L. monocytogenes and C. abortus and CVV were not detected, Brucella spp., Campylobacter spp., and C. burnetii were detected in 19 (15.2%), 4 (3.2%), and 2 (1.6%) of the bovine foetuses, respectively. Brucella and Campylobacter species were identified by molecular testing as B. melitensis (n = 4) and B. abortus (n = 15) and C. jejuni (n = 2) and C. foetus subsp. foetus (n = 2), respectively.

CONCLUSIONS

The findings of this study suggest that Brucella spp., Campylobacter spp., and C. burnetii could pose a threat to both cattle and human health in the studied regions. Further studies are required to determine the exact role of these agents in cattle reproductive losses in Türkiye, as well as the economic impact of these agents on livestock.

Exposure of broiler chickens to deoxynivalenol and Campylobacter jejuni induces substantial changes in intestinal gene expression

The mycotoxin deoxynivalenol (DON) is of high importance among feed contaminants because of its frequent occurrence in toxicologically relevant concentrations worldwide. Cereal crops, the main component of chicken diet, are commonly contaminated with DON, resulting in frequent exposure of chickens to DON. Likewise, Campylobacter (C.), a pathogen of major public and animal health concern, is frequently found in chicken flocks and poses a threat to the One Health approach. Campylobacter colonizes the gastrointestinal (GI) tract of poultry with a high bacterial load in the caeca. However, the mechanism of C. jejuni colonization in chickens is still not understood albeit it is well known that C. jejuni resides primarily in the mucosal layer of the chicken intestine. Therefore, in the actual study we focused on the effect of exposure to DON and/or C. jejuni on expression profiles of intestinal mucins (MUC1, MUC2), β-defensins (Gallinacin (GAL) 10, 12), cytokines (Toll-like receptor 2 (TLR2), Interleukin (IL) 6, 8, Interferon-γ (IFN)-γ), inducible nitric oxide synthase 2 (iNOS2), as well as selected tight junction proteins (Claudin 5 (CLDN5), Occludin (OCLN), and zonula occludens-1 (ZO1) via RT-qPCR. For this, a total of 150 one-day-old Ross 308 broiler chickens were randomly allocated to six different groups (n = 25 with 5 replicates/group) and were fed for 5 weeks with either contaminated diets (5 or 10 mg DON/kg feed) or basal diets (control). Following oral infection of birds with C. jejuni NCTC 12744 at 14 days of age, several changes in gene expression patterns were demonstrated. A significant (P ≤ 0.05) downregulation of MUC2 mRNA expression was observed in birds fed DON5 and DON10 diet, as well as in birds co-exposed to DON5 and C. jejuni at 7 dpi. Furthermore, at 14 dpi, MUC2 mRNA expression was significantly (P ≤ 0.05) downregulated in birds fed DON (5 mg and 10 mg/kg diet) with and without C. jejuni and in birds infected solely with C. jejuni. The actual study also demonstrated that co-exposure of broiler chickens to DON and C. jejuni resulted in a decreased barrier function via downregulation of OCLD mRNA expression. In addition, Campylobacter infection induced an increased expression of the antimicrobial peptide GAL12 and the IL8 gene, indicating that C. jejuni can initiate an immune response in the chicken gut in a proinflammatory manner. Similarly, DON with and without C. jejuni induced upregulation of GAL10 and GAL12 mRNA expression at 7 dpi. Moreover, no change in iNOS2 mRNA expression was observed in both the jejunum and the cecum at either 7 dpi or 14 dpi, suggesting unchanged NO production during exposure/infection. In conclusion, we confirmed that DON contamination corresponding to the currently applicable EU guidance value of 5 mg DON/kg feed affects the intestinal gene expression profiles of broilers, mainly in a dose-independent manner. Furthermore, DON exposure interacted synergistically with C. jejuni challenge regarding mucins, innate immunity gene expression in either the jejunum or the cecum, suggesting immunomodulatory activity of both foodborne agents (DON and C. jejuni).

Genomic epidemiology of Salmonella Enteritidis human infections in the Netherlands, 2019 to 2023

Salmonella enterica serotype Enteritidis (SE) is a common foodborne pathogen that can cause human salmonellosis. Identifying closely related cases is essential to control the pathogen through, e.g. outbreak investigation, but it is often challenging due to the low genetic diversity of SE, particularly with traditional typing methods. This study aimed to investigate the population structure of SE genomes collected during routine surveillance in the Netherlands using whole-genome sequencing (WGS), their clustering, temporal distribution and the association between epidemiological and phenotypic antimicrobial resistance (AMR) factors and the persistence of SE clusters. We also investigated the distribution of genotypic AMR markers among these isolates. The study collection comprised 1,669 unique SE isolates from human infections collected from Dutch surveillance between 2019 and 2023, and their relatedness was derived using core-genome multi-locus sequence typing and Hamming distances. Based on the results, the 216 clusters comprised 1,085 sequences, in addition to 584 sequences depicted as singletons. These clusters predominantly fell within three major lineages, of which two were the previously described Global and Atlantic lineages. Of these clusters, approximately a third persisted for more than 1 year during the 5-year study period. However, no statistically significant associations were found between epidemiological factors, such as age, gender and travel history, or phenotypic AMR and the persistence of SE clusters. The most common AMR genetic markers observed were related to antimicrobial classes of (fluor)quinolones, β-lactamases and aminoglycosides. This study provides a better understanding of the genomic epidemiology of SE in the Netherlands based on WGS. Further analysis that includes samples from the food-chain supply, along with higher resolution methods during a post-Coronavirus Disease of 2019 (COVID-19) period, may provide more insights into the possible causes of the persistence of SE clusters.

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.

Antimicrobial resistance and genomic characteristics of Campylobacter spp. From Australian meat chickens with A follow up investigation

The increasing resistance of bacteria to antimicrobials is a major threat to public health. This study investigates the prevalence of antimicrobial resistance, both phenotypic and genotypic, among Campylobacter isolates from Australian meat chickens in 2022, as a follow up to investigate trends since the last national surveillance undertaken in 2016. Isolates (n = 186) were obtained at slaughter from 200 pooled cecal samples taken from 1,000 meat chickens. The majority of C. jejuni (68.7%) and C. coli (88.9%) isolates were susceptible to all the antibiotics that were tested, and no multi-drug resistance was found. Resistance to ciprofloxacin (fluoroquinolone) was detected in 24.4% of the C. jejuni and 3.2% of the C. coli isolates. Whole genome sequencing revealed a diverse range of sequence types (STs). These included 32 previously reported STs for C. jejuni and 13 for C. coli, as well as four and seven previously undescribed STs for each species, respectively. The STs containing fluoroquinolone-resistant isolates were ST2083, ST10130, ST2895, ST7323, ST2398, and ST1078 for C. jejuni, and ST860 and ST894 for C. coli. Although fluoroquinolones are not used in animal production in Australia, resistance amongst C. jejuni isolates was high (24.4%). This finding emphasizes the need for enhanced surveillance and regular sampling along the food chain to understand the source of the isolates and to mitigate risks of antimicrobial resistance to protect public health.

Big data analytics in food industry: a state-of-the-art literature review

The food industry has experienced rapid growth over the past two decades, driven by technological advancements that have generated vast quantities of complex data. However, the industry's ability to effectively analyze and leverage this data remains limited due to the lack of control over diverse variables. This review addresses a critical gap by exploring how AI-ML-based approaches can be applied to solve key challenges in the food sector.

A single nucleotide polymorphism produces different transcription profiles in Campylobacter jejuni's cysM

A single nucleotide polymorphism (SNP) in the 126 bp untranslated region (UTR) directly upstream of Campylobacter jejuni's cysM (cysteine synthase) results in significant effects on gene transcription. UTR sequences, containing the predicted promoter region of cysM, from 264 different strains were compared, and revealed a SNP twenty nucleotides upstream of the cysM translation start site. In 219 strains the UTR sequence contained a guanine at this locus, and the remaining 45 strains had an adenine at the same position. Strains possessing the guanine SNP showed higher amounts of cysM transcripts compared to adenine SNP strains. When both UTR regions were cloned upstream of the major flagellar subunit (flaA) the guanine SNP UTR resulted in significantly greater levels of flaA transcription compared to the adenine SNP containing UTR. Additionally, when the UTR containing the guanine SNP was fused to flaA, motility was restored for a flaAB null mutant. Motility was not rescued initially when flaA was fused to the UTR containing the adenine SNP UTR. However, when the flaAB null mutant, containing a copy of flaA fused to the adenine-containing UTR, was incubated in Brucella broth for a minimum of two consecutive passages each lasting 48 h, transcription of flaA increased and motility was restored. Additional analysis of the flaA mRNA produced by the strain containing the adenine SNP UTR fused to flaA grown in Brucella broth versus agar suggests that the effects on motility occurred through blocking of full-length mRNA production.

Trained immunity using probiotics and inactivated pathogens enhances resistance to Salmonella enterica serovar Typhimurium infection by activating the cGAS-STING signal pathway in mice and chickens

INTRODUCTION

Concerns about antibiotic resistance have prompted interest in alternative strategies for enhancing disease resistance, particularly in livestock and poultry production.

OBJECTIVES

This study explored the role of trained immunity in enhancing resistance to Salmonella enterica serovar Typhimurium (S. Typhimurium) infection in mice and chickens.

METHODS

We investigated the effects of probiotics and inactivated pathogenic bacterial strains on host immunity in Toll-like receptor 2-deficient mice (TLR2-/-) to assess whether these effects were related to bacterial outer membrane components such as peptidoglycan (PNG), lipoarabinomannan (LAM) and lipoteichoic acid (LTA). Bacterial genomes were evaluated for their ability to enhance the host immune system. Macrophage-depletion models were used to identify the key immune cells involved in trained immunity, with a focus on the cGAS-STING pathway.

RESULTS

Probiotics and inactivated pathogenic strains enhanced host immunity and protected against S. Typhimurium infection. As demonstrated in the TLR2-deficient mice, the effects were not dependent on bacterial outer membrane components. Instead, bacterial genomes played a significant role in activating trained immunity. Macrophages were identified as the primary cells that mediated the response with the cGAS-STING pathway playing a crucial role. The results observed using the mouse models led to investigating the potential application of trained immunity in poultry.

CONCLUSION

Trained immunity activated by probiotics and inactivated bacterial pathogens enhanced resistance against S. Typhimurium infection via macrophage activation and involved the cGAS-STING pathway. These findings highlight the potential of trained immunity as an alternative strategy for disease prevention in both livestock and poultry.

Applications of Machine Learning in Food Safety and HACCP Monitoring of Animal-Source Foods

Integrating advanced computing techniques into food safety management has attracted significant attention recently. Machine learning (ML) algorithms offer innovative solutions for Hazard Analysis Critical Control Point (HACCP) monitoring by providing advanced data analysis capabilities and have proven to be powerful tools for assessing the safety of Animal-Source Foods (ASFs). Studies that link ML with HACCP monitoring in ASFs are limited. The present review provides an overview of ML, feature extraction, and selection algorithms employed for food safety. Several non-destructive techniques are presented, including spectroscopic methods, smartphone-based sensors, paper chromogenic arrays, machine vision, and hyperspectral imaging combined with ML algorithms. Prospects include enhancing predictive models for food safety with the development of hybrid Artificial Intelligence (AI) models and the automation of quality control processes using AI-driven computer vision, which could revolutionize food safety inspections. However, handling conceivable inclinations in AI models is vital to guaranteeing reasonable and exact hazard assessments in an assortment of nourishment generation settings. Moreover, moving forward, the interpretability of ML models will make them more straightforward and dependable. Conclusively, applying ML algorithms allows real-time monitoring and predictive analytics and can significantly reduce the risks associated with ASF consumption.

The ability of Salmonella enterica subsp. enterica strains to form biofilms on abiotic surfaces and their susceptibility to selected essential oil components

The ability of Salmonella enterica subsp. enterica to persist and form biofilms on different surfaces can constitute a source of food contamination, being an issue of global concern. The objective of this study was to understand the biofilm formation profile of 14 S. enterica strains among different serovars and sources and to evaluate the ability of essential oil (EO) components (carveol, citronellol, and citronellal) to disinfect the biofilms formed on stainless steel and polypropylene surfaces. All the strains were able to form biofilms with counts between 5.34 to 6.78 log CFU cm-2. Then, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of EO components were evaluated on two selected strains. All compounds inhibited the growth of Salmonella Typhimurium (strain 1; MIC = 800-1000 µg ml-1) and Salmonella Enteritidis (strain 5; MIC = 400-1000 µg ml-1) and only carveol showed bactericidal activity against strains 1 and 5 (MBC = 1200 µg ml-1). Biofilms were exposed to the EO components at 10 × MIC for 30 min and polypropylene surfaces were more difficult to disinfect showing reductions between 0.9 and <1.2 log CFU cm-2. In general, the S. enterica biofilms demonstrated a significant tolerance to disinfection, demonstrating their high degree of recalcitrance on food processing surfaces.

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.

Dynamic Serotype Distribution and Antimicrobial Resistance of Salmonella Isolates from 2019 to 2023 in Guizhou, China

Introduction

Salmonella, a leading cause of human infectious diarrhea diseases, foodborne illness, and zoonotic infections, poses a significant health burden.

Methods

A retrospective screening was performed to elucidate the serotype distribution and antimicrobial resistance of 933 human Salmonella isolates from nine cities (prefectures) in Guizhou province of southwestern China between 2019 and 2023 through slide agglutination and antimicrobial resistance testing.

Results

Fifty-four different serotypes were identified in this study, with S. Typhimurium (44.4%) and S. Enteritidis (20.7%) being the predominant serotypes, followed by S. London (3.1%), S. Derby (2.8%), and S. Rissen (2.0%). A total of 39 serotypes were reported for the first time in Guizhou province, and 121 isolates (13.0%) could not be classified. The diversity of Salmonella serotypes in Guizhou has increased from 8 in 2019 to 39 in 2023. In addition, the detection rate of S. Enteritidis showed a decreasing trend over time, while the detection rate of S. Typhimurium demonstrated an annual increase since 2020. For 933 isolates, a significant majority (94.0%) exhibited resistance to at least one class of antimicrobial agents. The highest resistance observed was to ampicillin (86.4%), followed by resistance to tetracycline (76.3%) and streptomycin (72.8%). Notably, we discovered that the resistance rate to colistin was 4.7%, with 93.2% of these isolates being S. Enteritidis. Meanwhile, 78.5% of isolates were demonstrated multidrug resistance (MDR), with the MDR rates for S. Rissen and S. Typhimurium exceeding 90%. Additionally, 5.7% of Salmonella isolates were extensively drug-resistant (XDR), with S. Typhimurium and S. Enteritidis exhibiting XDR rates of 5.1% and 4.1%, respectively. The rate of MDR and XDR in Salmonella peaked in 2019 and then gradually declined from 2020 to 2022, rising again in 2023.

Conclusion

Our research revealed an increasing diversity in Salmonella serotypes within Guizhou province, alongside significant challenges posed by MDR and a rising XDR rate. Therefore, it is essential to continuously improve the surveillance of Salmonella, keep track of changes in serotype distribution and dynamic shifts, and strengthen the persistent monitoring of antimicrobial agents.

Epitope mapping of recombinant Salmonella enterica serotype Heidelberg flagellar hook-associated protein by in silico and in vivo approaches

BACKGROUND

Salmonella is a leading cause of human acute bacterial gastroenteritis worldwide. Outbreaks of human salmonellosis have often been associated with consumption of contaminated poultry products. Various strategies have been explored to control this microorganism during poultry production and processing. Vaccination of broiler chickens is regarded as one of the effectives means to control this microorganism. The aim of the present study was to compare the epitope identification in the Salmonella enterica serotype Heidelberg FlgK protein by in silico prediction and in vivo experiment with mass spectrometry in association with immunoprecipitation proteomics.

RESULTS

The Salmonella serotype Heidelberg FlgK protein contains 553 amino acids with a molecular mass of 61 kDa. This protein is conserved among Salmonella serotype Heidelberg isolates. The results show that both approaches identified three common shared consensus peptide epitope sequences at the positions of 77-95, 243-255 and 358-373 in the Salmonella serotype Heidelberg FlgK protein.

CONCLUSIONS

These findings provide a rational for further evaluation of these shared linear epitopes in vaccine development to cover the chicken population.

Detection of Coxiella burnetii in Bulk Tank Milk of Dairy Small Ruminant Farms in Greece

The objectives of this work were as follows: (i) the evaluation of the prevalence of detection of genetic material of Coxiella burnetii in the bulk tank milk of sheep and goat farms in Greece and (ii) the investigation of variables related to the management applied in farms as possible predictors for this. The presence of C. burnetii genetic material was studied in the bulk tank milk of 325 sheep and 119 goat farms throughout the country. For qualitative and quantitative identification of the genetic material of the pathogen, a commercially available real-time PCR was used. In total, 45 parameters were assessed for potential association with the detection of the pathogen: these referred to the management system, infrastructure, health management, animals, production characteristics, and human resources on the farms. Genetic material of the pathogen was detected in bulk tank milk samples from nine sheep (2.8%) and six goat (5.0%) farms. Genetic material was at significantly higher median concentrations in samples from goat farms than from sheep farms, 1,078,096 (min: 181,121, max: 2,331,386) versus 15,728 (min: 507, max: 505,852) GE mL-1, respectively. For sheep farms, the intensive or semi-intensive management system applied in farms (p = 0.003), and for goat farms, the intensive or semi-intensive management system applied in farms (p = 0.0007) and the smaller number of annual veterinary visits to farms (p = 0.044) emerged as significant predictors. Among sheep farms managed under the intensive or semi-intensive system, the lack of accessory barns on farms (p = 0.024) emerged as a significant predictor; no significant predictor could be found among goat farms under such management systems. There was no significant difference in production outcomes between farms in which C. burnetii was or was not detected in the bulk tank milk; also, there was no association between the detection of C. burnetii and the annual incidence rate of cases of abortion on the farms. The results suggest that the risk of transfer of C. burnetii to dairy products from sheep and goat milk appears to be small, but not negligible, which indicates that the pasteurization of milk from small ruminants must be carried out consistently and correctly to ensure the safety of the product.

Bacillus safensis APC 4099 has broad-spectrum antimicrobial activity against both bacteria and fungi and produces several antimicrobial peptides, including the novel circular bacteriocin safencin E

Bacillus safensis APC 4099, isolated from bees' gut, has been identified as a promising candidate for food biopreservation. Antimicrobial activity screening revealed a broad-spectrum inhibition potential, ranging from gram-positive pathogenic bacteria to fungi responsible for food spoilage. Genomic analysis identified biosynthetic gene clusters coding for several antimicrobial peptides and secondary metabolites. Specifically, a novel, anionic, 6 kDa circular bacteriocin, named safencin E, was detected, showing 52.5% similarity to butyrivibriocin AR10. Additionally, gene clusters coding for the biosynthesis of bacteriocins such as pumilarin and plantazolicin and biosynthetic pathways for secondary metabolites, including pumilacidin A, bacilysin, and bacillibactin, were identified. Matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis detected molecular masses correlating to safencin E, plantazolicin, pumilarin, and pumilacidin A from the cell-free supernatant, cell extracts, or both. Overall, the broad-spectrum antimicrobial activity of B. safensis APC 4099 indicates that this strain is a promising candidate for the biological control of food ecosystems and thus has the potential to enhance food safety.

IMPORTANCE

The present article highlights the importance of the strain Bacillus safensis APC 4099 as a potential biocontrol agent. The strain possesses biosynthetic gene clusters coding for various antimicrobial peptides and secondary metabolites, including a novel circular bacteriocin, safencin E, and the bacteriocins pumilarin and plantazolicin. This diversity in the production of antimicrobial peptides renders the producer with broad-spectrum antimicrobial activity, ranging from gram-positive pathogenic and spoilage bacteria to spoilage molds. Considering that 1.3 billion tons of food appropriate for human consumption is lost or wasted annually, identifying strains or novel antimicrobial peptides capable of biopreservation is highly relevant. This strain and its bioactive compounds offer a solution to this global problem as biocontrol agents for food ecosystems against spoilage and pathogenic microbes.

Emerging Resistance and Virulence Patterns in Salmonella enterica: Insights into Silver Nanoparticles as an Antimicrobial Strategy

BACKGROUND/OBJECTIVES

This study aims to characterize antibiotic resistance (AR) and virulence markers in Salmonella spp. isolated from Romanian outpatients' stool samples.

METHODS

In 2019, community-acquired Salmonella strains were collected and identified using MALDI-TOF mass spectrometry, antibiotic susceptibility profiles have been determined with the MicroScan system, and soluble virulence factors were evaluated using specific culture media, while biofilm formation was quantified in 96-well plates. Molecular analysis targeted resistance genes for β-lactams (e.g., blaTEM and blaSHV); tetracyclines (e.g., tet(A)); sulphonamides; and quinolones, as well as virulence genes (e.g., invA, spvC, pldA, and held). Whole-genome sequencing (WGS) was performed on 19 selected isolates. A silver nanoparticles (AgNPsol) alternative to conventional antibiotics was tested for effectiveness against multidrug-resistant (MDR) isolates.

RESULTS

From the total of 309 Salmonella isolates (65.05% from children under 4 years of age) belonging to four subtypes and four serovars, 27.86% showed resistance to at least one antibiotic, most frequently to tetracycline, ampicillin, and piperacillin. The strains frequently expressed haemolysin (67%), aesculinase (65%), and gelatinase (62%). Resistance to trimethoprim-sulfamethoxazole was encoded by the sul1 gene in 44.83% of the strains and to tetracyclines by the tet(A) gene (59.52%). The ESBL genes blaTEM, blaSHV, and blaCTX-M were detected by PCR in 16.18%, 2.91%, and 0.65% of the strains, respectively. Additionally, 98.63% of the strains carried the invA marker, with notable positive associations between blaSHV, qnrB, and sul1 with spvC.

CONCLUSIONS

The present findings revealed significant patterns in Salmonella isolates, subtypes, serovars, AR, and virulence, emphasising the need for continuous surveillance of Salmonella infections. Additionally, the potential of AgNPs as an alternative treatment option was demonstrated, particularly for paediatric S. enterica infections.

A novel approach for detecting Salmonella enterica strains frequently attributed to human illness-development and validation of the highly pathogenic Salmonella (HPS) multiplex PCR assay

Introduction

Non-typhoidal Salmonella enterica (NTS) are leading bacterial agents of foodborne illnesses and a global concern for human health. While there are over 2,600 different serovars of NTS, epidemiological data suggests that certain serovars are better at causing disease than others, resulting in the majority of reported human illnesses in the United States. To improve food safety, there is a need to rapidly detect these more pathogenic serovars to facilitate their removal from the food supply.

Methods

Addressing this need, we conducted a comparative analysis of 23 closed Salmonella genomic sequences of five serotypes. The analysis pinpointed eight genes (sseK2, sseK3, gtgA/gogA, avrA, lpfB, SspH2, spvD, and invA) that in combination, identify 7 of the 10 leading Salmonella serovars attributed to human illnesses in the US each year (i.e., Serovars of Concern or SoC). A multiplex PCR assay was developed to detect the presence of these genes, with strains amplifying five or more targets designated Highly Pathogenic Salmonella, or HPS. The utility of the resulting HPS assay for identifying SoC was examined in silico, using BLAST to determine the distribution of gene targets among closed Salmonella genome sequences in GenBank (n = 2,192 representing 148 serotypes) and by assaying 1,303 Salmonella (69 serotypes), isolated from FSIS regulatory samples.

Results and discussion

Comparison of serotypes identified by the assay as HPS, with those identified as SoC, produced an Area Under the Curve (AUC) of 92.2% with a specificity of 96% and a positive predictive value of 97.4%, indicating the HPS assay has strong ability to identify SoC. The data presented lay the groundwork for development of rapid commercial assays for the detection of SoC.

Evaluation of the potential of phage phSE-5 to fight Salmonella Typhimurium in milk, liquid whole egg, and eggshell

AIMS

This study aimed to evaluate the potential of phage phSE-5 to inactivate Salmonella enterica serovar Typhimurium in milk (at 4, 10, and 25°C), liquid whole egg, and eggshell (at 25°C for both matrices).

METHODS AND RESULTS

Since the success of phage treatment in food depends on maintaining phage viability towards different food conditions, firstly the stability of phage phSE-5 at different temperatures and pHs was assessed. The effect of phage phSE-5 against S. Typhimurium was then assessed in vitro (liquid culture medium-TSB) and finally in the selected food matrices. Phage phSE-5 was stable for long storage periods (56 days) at pH 7-8 and 4-25°C. At 25°C, the efficacy of phage phSE-5 was matrix-dependent with differences in the sample, relatively to the bacterial control, of 2.7, 4.6, 1.8, and 1.3 log colony-forming units (CFU) ml-1 in TSB, milk, liquid whole egg, and eggshell, respectively. Also, phage phSE-5 led to reductions relatively to the initial bacterial concentration only in TSB and milk with 1.9 and 2.1 log CFU ml-1 reduction, respectively. Additionally, this phage was more efficient at 25°C in the tested matrices than at 10°C (no reduction and 1.7 log CFU ml-1 reduction in TSB and milk, respectively; maximum difference of 1.7 and 3.3 log CFU ml-1 in TSB and milk, respectively) and 4°C (no bacterial reduction/difference was observed in both TSB and milk). However, the decrease in temperature from 25 to 10°C slowed down bacterial regrowth after phage treatment.

CONCLUSIONS

Our results show that phages are promising and environmentally friendly candidates for use as biocontrol agents against S. Typhimurium in milk, liquid whole egg, and eggshell, allowing a reduction in energy costs if carried out at 10°C.

An insight into the applications of bacteriophages against food-borne pathogens

Novel and emerging pathogens, enduring contamination, antibiotic resistance, an environment that is always changing, and the complexity of food production systems all contribute to the worsening of foodborne illness. It has been proposed that bacteriophages can serve as both fast food-borne pathogen detection tools and natural food preservatives in a variety of foods. Phages, like many other antimicrobial interventions used in food production systems, are not a cure-all for issues related to food safety, though. Consequently, phage-based biocontrol has a generally narrower antibacterial spectrum than most antibiotics, even though it can be promising in the fight against foodborne infections. Among the difficulties phage-based biocontrol techniques encounter are forming phage-insensitive single-cell variations and creating potent cocktails. To better understand when and where phage-based applications can be successfully implemented at the production and processing levels, this review focuses on phage-based applications at crucial control points in food production systems.

Inhibiting potential of selected lactic acid bacteria isolated from Costa Rican agro-industrial waste against Salmonella sp. in yogurt

This study aimed to characterize lactic acid bacteria (LAB) isolated from Costa Rican agro-industrial waste and explore their bioprotective potential against Salmonella in yogurt. A total of 43 LAB isolates were identified using the 16S rRNA region. In vitro inhibition of Salmonella, Listeria monocytogenes, Staphylococcus aureus, and Escherichia coli was determined. A total of 15 of the 43 isolates showed a good to strong antimicrobial effect against at least two pathogens. A total of 14 selected isolates were evaluated for antibiotic resistance, gelatinase, and hemolytic activity. The bioprotective effect of the most promising strain, Lactiplantibacillus pentosus, was assessed against Salmonella sp. during yogurt fermentation. All the isolates were resistant to vancomycin and showed variable degrees of susceptibility to other antibiotics. All of the isolates were negative for gelatinase, and 5 isolates had no hemolytic activity. A significant inhibitory effect of L. pentosus_58(6)-2I (p<0.05) against Salmonella during fermentation was found, but pathogen reduction was limited to 0.611 log CFU/mL.

Pathogenicity and virulence of Campylobacter jejuni: What do we really know?

Campylobacter jejuni is the leading cause of bacterial gastroenteritis and is a major public health concern worldwide. Despite its importance, our understanding of how C. jejuni causes diarrhoea and interacts with its hosts is limited due to the absence of appropriate infection models and established virulence factors found in other enteric pathogens. Additionally, despite its genetic diversity, non-pathogenic C. jejuni strains are unknown. Regardless of these limitations, significant progress has been made in understanding how C. jejuni uses a complex array of factors which aid the bacterium to survive and respond to host defences. This review provides an update on fitness and virulence determinants of this important pathogen and questions our knowledge on these determinants that are often based on inferred genomics knowledge and surrogate infection models.

European Food Safety Authority (EFSA), European Centre for Disease Prevention and Control (ECDC). 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.

Pediatric trichinosis: A case report

BACKGROUND

Trichinellosis is a zoonosis, caused by roundworms of the genus Trichinella. Domestic pigs, wild boars, bears, rodents and horses are reservoir animals. We report a case of neck trichinosis presenting as lateral neck swelling. The diagnosis of trichinosis was confirmed by the presence of larvae on muscle biopsy. Furthermore, lateral neck swelling may provide a diagnostic challenge by clinically mimicking a lymphoma or other causes of lateral neck swelling. Due to its rarity and its tendency to pose a clinical diagnostic challenge, we decided to report it.

CASE PRESENTATION

A-10 yr old male patient presented with a 6 × 4 cm firm; non-tender left lateral neck swelling. Histopathology examination confirmed the diagnosis of trichinosis and the patient was started on albendazole 15 mg/kg/day, divided into two doses and prednisolone 20 mg by mouth, two times daily, for 14 days. Having completed his medication, he had a smooth course and was discharged with appointment scheduled for follow-up after 3 months.

DISCUSSION

Trichinella spp. occur worldwide, most frequently in regions with temperate climates. About 10,000 human infections occur annually worldwide. Cultural factors such as traditional dishes based on raw or undercooked meat or meat-derived products play an important role in the epidemiology of the disease.

CONCLUSION

In the clinical evaluation of a patient with lateral neck swelling, trichinosis must be considered as a differential diagnosis in subjects from endemic areas for early diagnostic workup and management.

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.

Liver failure after Bacillus cereus food poisoning, an under-recognized entity: A case report

BACKGROUND

Bacillus cereus (B. cereus) is known to cause 2 types of foodborne diseases; the diarrheal and emetic syndromes. They are largely underreported due to their usually self-limiting course. Rare and sometimes fatal cases of liver failure, pulmonary hemorrhage and cerebral oedema have been reported mainly in children and young adults. We present here a case of liver failure associated with B. cereus food poisoning in a middle-aged patient.

CASE SUMMARY

A 48-year-old female patient presented to the emergency department for emesis, diarrhea, chills without fever, asthenia and diffuse abdominal cramps that started less than 30 minutes after eating a rice salad. Her past medical history was relevant for cholecystectomy and a cured Hashimoto's disease. She did not take any medication, drugs and declared a consumption of one glass of wine per week. In the emergency department, she was treated with acetaminophen, metoclopramide, ondansetron, and an intravenous normal saline infusion. Blood gas analysis revealed a metabolic acidosis with hyperlactatemia, coagulation revealed a low prothrombin activity [32 %; normal values (N): 70-140] and a low Factor V activity (15%; N: > 70). Transaminases were elevated with hyperbilirubinemia, elevated lipase and rhabdomyolysis. N-acetylcysteine treatment was introduced. Abdominal echography revealed no signs of chronic hepatopathy or hepatomegaly. Day after the admission, psychomotor activity improved, transaminases and lipase started decreasing. Rhabdomyolysis gradually worsened to peak on day 3. Screening tests for liver disease were negative for viral and autoimmune cause of liver failure. Stools cultures were positive for colonies of the B. cereus group which were also identified in the rice salad samples processed whereas blood cultures were negative. The patient's condition improved gradually including her liver function parameters and psychomotor activity which allowed her discharged home on day 9.

CONCLUSION

We describe a rare case of hepatocellular dysfunction due to a foodborne B. cereus intoxication in an adult patient. Even if it is uncommon, the severity of liver dysfunction reported and mechanism of the cereulide toxin toxicity on liver suggest that acetaminophen should be avoided in case of a foodborne intoxication and n-acetylcysteine could be a potential therapy helping to prevent hepatocytes necrosis due to the oxidative stress induced by mitochondrial dysfunction.

Characterization of two Campylobacter jejuni phages and evaluation of their antibacterial efficacy with EDTA

Campylobacter jejuni is a leading cause of foodborne illness worldwide. The application of bacteriophages offers a promising approach to specifically target and reduce C. jejuni contamination in food products. In this study, two C. jejuni phages were characterized, and their ability to inhibit bacterial growth in combination with ethylenediaminetetraacetic acid (EDTA) was investigated. Both phages exhibited tolerance to a wide range of temperature (4-60 °C) and pH (3-9). Phage vB_CjeM-PC10 and vB_CjeM-PC22 were found to have a latent period of 30 min and 20 min and a burst size of 7 and 35 PFU/cell, respectively. Phage vB_CjeM-PC10 has a linear double-stranded DNA (dsDNA) genome of 51,148 bp with 77 ORFs and 29% GC content. Phage vB_CjeM-PC22 has a circular dsDNA genome of 32,543 bp with 56 ORFs and 28% GC content. At 42 °C, the combination of these phages (MOI = 10) and EDTA decreased the count of viable C. jejuni by 5.2 log10 and inhibited the regrowth of resistant cells for 48 h. At 4 °C, phage vB_CjeM-PC10 alone (MOI = 1000) reduced the count of viable C. jejuni by 3 log10 in brain heart infusion (BHI) broth and 2 log10 on chicken skin after incubation for 48 h. Although these phages were effective against C. jejuni, they cannot be utilized directly for food safety applications because they are lysogenic. Nevertheless, these findings expand the genome library of C. jejuni phages and enrich data resources by highlighting potential strategies for controlling C. jejuni infections.

Genome sequencing and analysis of Salmonella enterica subsp. enterica serotype Enteritidis PT4 578: insights into pathogenicity and virulence

Salmonella enterica serotype Enteritidis is a generalist serotype that adapts to different hosts and transmission niches. It has significant epidemiological relevance and is among the most prevalent serotypes distributed in several countries. Salmonella Enteritidis causes self-limited gastroenteritis in humans, which can progress to systemic infection in immunocompromised individuals. The Salmonella pathogenicity mechanism is multifactorial and complex, including the presence of virulence factors that are encoded by virulence genes. Poultry products are considered significant reservoirs of many Salmonella serotypes, and Salmonella Enteritidis infections are often related to the consumption of chicken meat and eggs. This study reports the whole-genome sequence of Salmonella Enteritidis PT4 strain 578. A total of 165 genes (3.66%) of the 4506 coding sequences (CDS) predicted in its genome are virulence factors associated with cell invasion, intestinal colonization, and intracellular survival. The genome harbours twelve Salmonella pathogenicity islands (SPIs), with the SPI-1 and SPI-2 genes encoding type III secretion systems (T3SS) showing high conservation. Six prophage-related sequences were found, with regions of intact prophages corresponding to Salmon_118970_sal3 and Gifsy-2. The genome also contains two CRISPR systems. Comparative genome analysis with Salmonella Enteritidis ATCC 13076, Salmonella Typhimurium ATCC 13311, and Salmonella Typhimurium ATCC 14028 demonstrates that most unshared genes are related to metabolism, membrane, and hypothetical proteins. Finally, the phenotypic characterization evidenced differences among Salmonella Enteritidis PT4 578 and the other three serotypes regarding the expression of the red, dry, and rough (rdar) morphotype and biofilm formation. Overall, the genomic characterization and phenotypic properties expand knowledge of the mechanisms of pathogenicity in Salmonella Enteritidis PT4 578.

Prevalence and Antimicrobial Susceptibility of Foodborne Pathogens from Raw Livestock Meat in China, 2021

The rising prevalence of pathogenic bacteria in livestock meat poses a growing public health concern in China. The determination of antimicrobial resistance (AMR) is critical for the clinical management of foodborne infections stemming from livestock meat consumption. This study aimed to assess the prevalence of pathogenic bacteria in livestock meat (pork, beef, and mutton) sampled in China in 2021 and to identify the most common AMR patterns among the isolated pathogens. A total of 2515 raw livestock meat samples were collected across 15 provinces in China during 2021. Pathogen detection, including Listeria monocytogenes, Salmonella, and diarrheagenic Escherichia coli (DEC), followed China's national food safety standards. All Salmonella isolates underwent serotyping via slide agglutination. Antimicrobial susceptibility of Salmonella and DEC isolates was assessed using the broth dilution method. The detection rates for L. monocytogenes, Salmonella, and DEC in raw livestock meat were 9.06% (228/2, 515), 10.54% (265/2, 515), and 6.16% (155/2, 515), respectively. Pork showed the highest contamination rates for Salmonella and DEC, with prevalence rates of 17.60% (214/1, 216, χ2 = 124.62, p < 0.05) and 7.89% (96/1, 216, χ2 = 14.466, p < 0.05), respectively. L. monocytogenes contamination was notably higher in chilled (14.43%, 84/582) and frozen (12.39%, 55/444) meat than in fresh meat (χ2 = 43.510, p < 0.05). In contrast, Salmonella (12.09%, 180/1489, χ2 = 15.173, p < 0.05) and DEC (7.25%, 108/1489, χ2 = 12.275, p < 0.05) were more prevalent in fresh meat than in chilled or frozen samples. The predominant Salmonella serotypes identified were Salmonella enterica subsp. enterica serovar Typhimurium, followed by Salmonella enterica serovar Derby, Salmonella enterica serovar Rissen, Salmonella enterica serovar London, and Salmonella enterica serotype Enteritidis. Enteroaggregative E. coli was the most frequent pathotype among DEC (84.7%, 133/157), followed by enteropathogenic E. coli (8.3%, 13/157) and enterohemorrhagic E. coli (5.1%, 8/157). Among the 14 tested antimicrobial agents, Salmonella isolates demonstrated an overall resistance rate of 87.50%, while DEC exhibited a resistance rate of 84.70%. Ampicillin and tetracycline showed the highest resistance rates in both pathogens. Multi-drug resistance (MDR) was observed in 67.53% of Salmonella isolates (183 isolates) and 57.96% of DEC isolates (91 isolates). This study highlights the significant contamination of retail raw livestock meat in China by L. monocytogenes, Salmonella, and DEC. The high resistance of MDR in both pathogens poses serious public health risks. Chinese food safety and veterinary authorities should implement stricter measures to control pathogen contamination and regulate the use of antimicrobials in livestock to mitigate these risks.

Relevant foodborne bacteria associated to pork production chain

Foodborne diseases affect millions of people globally, resulting in a huge number of hospitalizations and deaths. In this context, laboratory-based research is crucial to identify the major pathogens as well as the relevance of each one for distinct food production chains. Pork meat is very popular, being the most consumed meat in many countries and its inspection at the slaughterhouse is the main component of surveillance to protect consumers. Healthy pigs may carry pathogenic and antibiotic resistant bacteria that can be subsequently transferred to humans through the consumption of contaminated meat. Further, the food processing environment can harbor pathogenic persistent bacteria, representing a risk of cross-contamination to pork meat, demanding strict slaughtering procedures. Among these foodborne bacteria, Salmonella, Yersinia enterocolitica, Escherichia coli, Campylobacter spp., Listeria monocytogenes and Staphylococcus aureus are the most relevant in the pork production chain. Molecular subtyping has been fundamental for pathogen detection and also to track transmission, and nowadays it is a key component of the efforts to prevent and control foodborne diseases. In this chapter, characteristics of these major foodborne bacteria associated to pork meat will be addressed, including their occurrence and importance along the pork production chain, worldwide distribution, typing, as well as control and prevention measures from farm to fork.

Application of a microbial and pathogen source tracking toolbox to identify infrastructure problems in stormwater drainage networks: a case study

Water scarcity and increasing urbanization are forcing municipalities to consider alternative water sources, such as stormwater, to fill in water supply gaps or address hydromodification of receiving urban streams. Mounting evidence suggests that stormwater is often contaminated with human feces, even in stormwater drainage systems separate from sanitary sewers. Pinpointing sources of human contamination in drainage networks is challenging given the diverse sources of fecal pollution that can impact these systems and the non-specificity of traditional fecal indicator bacteria (FIB) for identifying these host sources. As such, we used a toolbox approach that encompassed microbial source tracking (MST), FIB monitoring, and bacterial pathogen monitoring to investigate microbial contamination of stormwater in an urban municipality. We demonstrate that human sewage frequently contaminated stormwater (in >50% of routine samples), based on the presence of the human fecal marker HF183, and often exceeded microbial water quality criteria. Arcobacter butzleri, a pathogen of emerging concern, was also detected in >50% of routine samples, with 75% of these pathogen-positive samples also being positive for the human fecal marker HF183, suggesting human municipal sewage as the likely source for this pathogen. MST and FIB were used to track human fecal pollution in the drainage network to the most likely point source of contamination, for which a sewage cross-connection was identified and confirmed using tracer dyes. These results point to the ubiquitous presence of human sewage in stormwater and also provide municipalities with the tools to identify sources of anthropogenic contamination in storm drainage networks.IMPORTANCEWater scarcity, increased urbanization, and population growth are driving municipalities worldwide to consider stormwater as an alternative water source in urban environments. However, many studies suggest that stormwater is relatively poor in terms of microbial water quality, is frequently contaminated with human sewage, and therefore could represent a potential health risk depending on the type of exposure (e.g., irrigation of community gardens). Traditional monitoring of water quality based on fecal bacteria does not provide any information about the sources of fecal pollution contaminating stormwater (i.e., animals/human feces). Herein, we present a case study that uses fecal bacterial monitoring, microbial source tracking, and bacterial pathogen analysis to identify a cross-connection that contributed to human fecal intrusion into an urban stormwater network. This microbial toolbox approach can be useful for municipalities in identifying infrastructure problems in stormwater drainage networks to reduce risks associated with water reuse.

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.

Q Fever in Greece and Factors of Exposure: A Multiregional Seroprevalence Study

INTRODUCTION

The epidemiology of Q fever, caused by Coxiella burnetii, varies significantly worldwide. This study aimed to document the prevalence of Coxiella burnetii in Greece by measuring specific IgG antibody levels in serum samples from the general population and high-risk groups, including farmers, veterinarians, and laboratory workers.

METHODOLOGY

A multiregional, stratified sampling design was employed, with 1,345 participants from Thessaly and Central Macedonia. Serum samples were tested for Coxiella burnetii IgG antibodies, and multivariate analysis was conducted to identify factors associated with seroprevalence.

RESULTS

Overall, 8.1% of participants tested positive for Coxiella burnetii antibodies, with the highest seroprevalence in Larissa (22.2%) and Karditsa (16.1%). High-risk occupational groups, particularly those with direct animal contact, showed a higher seroprevalence (13.6%). Multivariate analysis identified significant associations between seroprevalence and factors such as geographic region, occupation, and gender.

CONCLUSION

The study reveals regional and occupational disparities in Q fever seroprevalence in Greece, particularly in rural areas. These findings underscore the need for targeted public health measures, including heightened surveillance and preventive interventions for high-risk groups.

Quadruplex qPCR for detection and discrimination of C. Coli,C. fetus, and C. Jejuni from other Campylobacter species in chicken and sheep meat

Campylobacter is gram-negative bacteria considered the predominant genera isolated from poultry samples and associated with gastroenteritis. Due to the problems in conventional cultural methods of time-consuming and technically demanding requirements, a rapid and feasible method for their identification and discrimination of the closely related spp. Including Campylobacter coli, Campylobacter fetus, and Campylobacter jejuni is needed. This study analyzes the chicken and sheep meats samples (n = 125) using culture and pre-enrichment-based Quadraplex real-time PCR by targeting OrfA, CstA, HipO, and 16 S rRNA genes of C. coli, C. fetus, C. jejuni and Campylobacter spp. Respectively. The analysis of 125 chicken and sheep meat samples by culture and real-time PCR showed high concordance between the results of the two methods. The present study show high prevalence of Campylobacter species (35% and 32% from chicken and meat respectively) of which C. jejuni were the most abundant. Reaction efficiencies were between 90 and 110%, and detect as low as 8.9 fg in C. jejuni. The need for quick detection and discrimination methods in sheep and chicken meat can be met using the described Quadraplex real-time PCR methodology.

Activation of the l-fucose utilization cluster in Campylobacter jejuni induces proteomic changes and enhances Caco-2 cell invasion and fibronectin binding

Most Campylobacter jejuni isolates carry the fucose utilization cluster (Cj0480c-Cj0489) that supports the metabolism of l-fucose and d-arabinose. In this study we quantified l-fucose and d-arabinose metabolism and metabolite production, and the impact on Caco-2 cell interaction and binding to fibronectin, using C. jejuni NCTC11168 and the closely related human isolate C. jejuni strain 286. When cultured with l-fucose and d-arabinose, both isolates showed increased survival and production of acetate, pyruvate and succinate, and the respective signature metabolites lactate and glycolic acid, in line with an overall upregulation of l-fucose cluster proteins. In vitro Caco-2 cell studies and fibronectin-binding experiments showed a trend towards higher invasion and a significantly higher fibronectin binding efficacy of C. jejuni NCTC11168 cells grown with l-fucose and d-arabinose, while no significant differences were found with C. jejuni 286. Both fibronectin binding proteins, CadF and FlpA, were detected in the two isolates, but were not significantly differentially expressed in l-fucose or d-arabinose grown cells. Comparative proteomics analysis linked the C. jejuni NCTC11168 phenotypes uniquely to the more than 135-fold upregulated protein Cj0608, putative TolC-like component MacC, which, together with the detected Cj0606 and Cj0607 proteins, forms the tripartite secretion system MacABC with putative functions in antibiotic resistance, cell envelope stress response and virulence in Gram negative pathogenic bacteria. Further studies are required to elucidate the role of the MacABC system in C. jejuni cell surface structure modulation and virulence.

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.

Persistence of Salmonella and Campylobacter on Whole Chicken Carcasses under the Different Chlorine Concentrations Used in the Chill Tank of Processing Plants in Sri Lanka

The persistence of non-typhoidal Salmonella and Campylobacter in chicken meat is a considerable public health risk and a future challenge. This study aimed to determine the prevalence of Salmonella and Campylobacter in poultry processing lines where different chlorine concentrations were used in the chill tank. The samples were collected from four types of processing plants in Sri Lanka, considering the chlorine concentration used in the chill tank, which ranged from 2 ppm to 50 ppm. Salmonella and Campylobacter were isolated from whole carcass washings, neck skin, and cecal samples. Subsequently, an antimicrobial susceptibility test was performed for the isolates. The results revealed the overall prevalence of Salmonella and Campylobacter was 78.25% and 63.5%, respectively. Positive percentages of Salmonella and Campylobacter were high in the carcasses compared to the neck skin and ceca. The Campylobacter counts on the whole carcasses were significantly low (p < 0.001), at higher chlorine concentrations ranging from 20 to 30 ppm and 40 to 50 ppm. The pathogen prevalence in the whole carcasses was 84.7% Campylobacter coli, 39.1% Campylobacter jejuni, 71.1% Salmonella Typhimurium, and 28.8% Salmonella Infantis. The highest resistance was observed for tetracycline (63.8%) in Salmonella, while it was for gentamicin (87.8%) in Campylobacter. The prevalence percentage of multidrug-resistant Campylobacter was 51.2%, while it was 2.12% for Salmonella. The persistence of multidrug-resistant Salmonella and Campylobacter on the post-chill carcasses was highlighted in the present study as a significant public health threat that has to be addressed urgently.

Shiga Toxin-Producing Escherichia coli Strains from Romania: A Whole Genome-Based Description

The zoonotic Shiga toxin-producing Escherichia coli (STEC) group is unanimously regarded as exceptionally hazardous for humans. This study aimed to provide a genomic perspective on the STEC recovered sporadically from humans and have a foundation of internationally comparable data. Fifty clinical STEC isolates, representing the culture-confirmed infections reported by the STEC Reference Laboratory between 2016 and 2023, were subjected to whole-genome sequencing (WGS) analysis and sequences were interpreted using both commercial and public free bioinformatics tools. The WGS analysis revealed a genetically diverse population of STEC dominated by non-O157 serogroups commonly reported in human STEC infections in the European Union. The O26:H11 strains of ST21 lineage played a major role in the clinical disease resulting in hospitalisation and cases of paediatric HUS in Romania surpassing the O157:H7 strains. The latter were all clade 7 and mostly ST1804. Notably, among the Romanian isolates was a stx2a-harbouring cryptic clade I strain associated with a HUS case, stx2f- and stx2e-positive strains, and hybrid strains displaying a mixture of intestinal and extraintestinal virulence genes were found. As a clearer picture emerges of the STEC strains responsible for infections in Romania, further surveillance efforts are needed to uncover their prevalence, sources, and reservoirs.

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.

Antimicrobial Activity of Green Synthesized Silver and Copper Oxide Nanoparticles against the Foodborne Pathogen Campylobacter jejuni

Campylobacter jejuni is a major cause of global foodborne illnesses. To develop alternative antimicrobial strategies against C. jejuni, this study designed and optimized the green synthesis of metallic nanoparticles (NPs) with intracellular components of the medicinal fungus Ganoderma sessile to provide the needed reducing and stabilizing agents. NPs were characterized by transmission electron microscopy and dynamic light scattering, and the quasi-spherical NPs had sizes of 2.9 ± 0.9 nm for the copper oxide NPs and 14.7 ± 0.6 nm for the silver NPs. Surface charge assessment revealed zeta potentials of -21.0 ± 6.5 mV and -24.4 ± 7.9 mV for the copper oxide and silver NPs, respectively. The growth inhibition of C. jejuni by the NPs occurred through attachment to the outer cell membrane and subsequent intracellular internalization and resulted in minimum inhibitory concentrations of the silver NPs at 6 µg/mL and copper oxide NPs at 10 µg/mL. On the other hand, a differential ROS production caused by silver and copper NPs was observed. In summary, this research presents the first demonstration of using green synthesis with the medicinal fungus G. sessile to produce metallic NPs that effectively inhibit C. jejuni growth, providing a sustainable and effective approach to the traditional use of antimicrobials.

Emerging Strategies against Non-Typhoidal Salmonella: From Pathogenesis to Treatment

Even with the intensive efforts by public health programs to control and prevent it, non-typhoidal Salmonella (NTS) infection remains an important public health challenge. It is responsible for approximately 150 million illnesses and 60,000 deaths worldwide annually. NTS infection poses significant risks with high rates of morbidity and mortality, leading to potential short- and long-term complications. There is growing concern among health authorities about the increasing incidence of antimicrobial resistance, with multidrug resistance totaling 22.6% in Europe, highlighting an urgent need for new therapeutic approaches. Our review aims to provide a comprehensive overview of NTS infection. We outline the molecular mechanisms involved in the pathogenesis of NTS infection, as well as the events leading to invasive NTS infection and the subsequent complications associated with it. Given the widespread implications of antimicrobial resistance, our review also presents the global landscape of resistance, including multidrug resistance, and delve into the underlying mechanisms driving this resistance. The rising rates of antibiotic resistance frequently lead to treatment failures, emphasizing the importance of investigating alternative therapeutic options. Therefore, in this review we also explore potential alternative therapies that could offer promising approaches to treating NTS infections.

Interference of gastrointestinal barriers with antibiotic susceptibility of foodborne pathogens: an in vitro case study of ciprofloxacin and tetracycline against Salmonella enterica and Listeria monocytogenes

Minimum inhibitory concentrations (MIC) assays are often questioned for their representativeness. Especially when foodborne pathogens are tested, it is of crucial importance to also consider parameters of the human digestive system. Hence, the current study aimed to assess the inhibitory capacity of two antibiotics, ciprofloxacin and tetracycline, against Salmonella enterica and Listeria monocytogenes, under representative environmental conditions. More specifically, aspects of the harsh environment of the human gastrointestinal tract (GIT) were gradually added to the experimental conditions starting from simple aerobic lab conditions into an in vitro simulation of the GIT. In this way, the effects of parameters including the anoxic environment, physicochemical conditions of the GIT (low gastric pH, digestive enzymes, bile acids) and the gut microbiota were evaluated. The latter was simulated by including a representative consortium of selected gut bacteria species. In this study, the MIC of the two antibiotics against the relevant foodborne pathogens were established, under the previously mentioned environmental conditions. The results of S. enterica highlighted the importance of the anaerobic environment when conducting such studies, since the pathogen thrived under such conditions. Inclusion of physicochemical barriers led to exactly opposite results for S. enterica and L. monocytogenes since the former became more susceptible to ciprofloxacin while the latter showed lower susceptibility towards tetracycline. Finally, the inclusion of gut bacteria had a bactericidal effect against L. monocytogenes even in the absence of antibiotics, while gut bacteria protected S. enterica from the effect of ciprofloxacin.

Analysis of foodborne salmonellosis serotypes and drug resistance in children in Chenzhou City of China from 2017 through 2022

Background

Salmonella is a significant pathogens of foodborne illness. The widespread use of antibiotics in clinical practice and animal husbandry has resulted in increasing drug resistance of Salmonella. In this study, we examined the serotype distribution and drug resistance of Salmonella in pediatric patients with diarrhea in Chenzhou City to provide a basis for the scientific control and rational use of antibiotics in clinical practice in relation to Salmonellosis.

Methods

Stool Salmonella spp. were collected from patients younger than 18 years of age who met the definition for foodborne illness at two sentinel hospitals from 2017 through 2022 tested Salmonella, and a descriptive analysis of the epidemiologic characteristics. Salmonella strains isolated from the stool underwent serology and drug-sensitivity tests. The following 14 antibiotics were used for the drug-sensitivity tests: ampicillin (AMP), ampicillin/sulbactam (AMS), cefazolin (CFZ), cefoxitin, cefotaxime, ceftazidime, imipenem (IPM), tetracycline (TET), nalidixic acid, ciprofloxacin, chloramphenicol (CHL), gentamicin, trimethoprim/sulfamethoxazole (SXT), and azithromycin.

Results

Samples from 1,263 pediatric with diarrhea, and Salmonella was detected in 221 (17.5%) of these patients. Positive test results were principally observed in the second and third quarters of each year, accounting for 21.1% and 19.6% of the cases, respectively. The infection rates of infants aged less than 12 months and toddlers aged 1-3 years with diarrhea were the highest at 21.3% and 17.8%, respectively. The 221 Salmonella strains were divided into 32 serotypes, of which Salmonella Typhimurium (S. Typhimurium) was the dominant strain (79.2%). The resistance rates to TET (86.9%), AMP (75.6%), AMS (58.4%), CFZ (55.7%), CHL (54.3%), and SXT (45.2%) predominated, and the differences in the drug-resistance rates to 1st-, 2nd-, and 3rd-generation cephalosporins were high (2.3-55.7%). Only 0.9% of the strains were resistant to IPM. The multidrug resistance (MDR) rate was 76.5% (169/221), and 48.9% (108/221) of the strains were resistant to five or more classes of antibiotics, of which the most common drug-resistance profile was AMP-AMS-TET-CHL-CFZ-SXT, accounting for 10.9% of Salmonella strains (24/221).

Conclusions

Foodborne salmonellosis tended to occur during the summer and autumn in children, and infants and toddlers were more likely to develop salmonellosis than children in the other age groups. The dominant Salmonella serotype was S. Typhimurium. The drug-resistance rate of the tested strains was high, and the MDR problem was severe. We recommend that in the treatment of salmonellosis, antibiotics be selected rationally based on the drug-resistance status of local Salmonella resistance situation to ensure safety and efficacy.

Investigation of the Affinity of Aptamers for Bacteria by Surface Plasmon Resonance Imaging Using Nanosomes

The cell-SELEX method enables efficient selection of aptamers that bind whole bacterial cells. However, after selection, it is difficult to determine their binding affinities using common screening methods because of the large size of the bacteria. Here we propose a simple surface plasmon resonance imaging method (SPRi) for aptamer characterization using bacterial membrane vesicles, called nanosomes, instead of whole cells. Nanosomes were obtained from membrane fragments after mechanical cell disruption in order to preserve the external surface epitopes of the bacterium used for their production. The study was conducted on Bacillus cereus (B. cereus), a Gram-positive bacterium commonly found in soil, rice, vegetables, and dairy products. Four aptamers and one negative control were initially grafted onto a biochip. The binding of B. cereus cells and nanosomes to immobilized aptamers was then compared. The use of nanosomes instead of cells provided a 30-fold amplification of the SPRi signal, thus allowing the selection of aptamers with higher affinities. Aptamer SP15 was found to be the most sensitive and selective for B. cereus ATCC14579 nanosomes. It was then truncated into three new sequences (SP15M, SP15S1, and SP15S2) to reduce its size while preserving the binding site. Fitting the results of the SPRi signal for B. cereus nanosomes showed a similar trend for SP15 and SP15M, and a slightly higher apparent association rate constant kon for SP15S2, which is the truncation with a high probability of a G-quadruplex structure. These observations were confirmed on nanosomes from B. cereus ATCC14579 grown in milk and from the clinical strain B. cereus J066. The developed method was validated using fluorescence microscopy on whole B. cereus cells and the SP15M aptamer labeled with a rhodamine. This study showed that nanosomes can successfully mimic the bacterial membrane with great potential for facilitating the screening of specific ligands for bacteria.

Presence of integrons and their correlation with multidrug resistance in Salmonella enterica serovar Typhimurium: Exploratory systematic review

In Salmonella enterica serovar Typhimurium (Typhimurium), multidrug resistance is associated with integrons carrying resistance genes dispersed by mobile genetic elements. This exploratory systematic review sought to identify integron types and their resistance genes in multidrug resistance Typhimurium isolates. We used Medline, PubMed, SciELO, ScienceDirect, Redalyc, and Google Scholar as motor searchers for articles in Spanish or English published between 2012 and 2020, including the keywords “integrons”, “antibiotic resistance”, and “Salmonella Typhimurium”. We included 38 articles reporting multidrug resistance up to five antibiotic families. Class 1 integrons with aadA2 and blaPSE-1 gene cassettes were predominant, some probably related to the Salmonella genomic island 1. We did not find studies detailing class 1 and 2 integrons in the same isolate, nor class 3 integrons reported. The presence of integrons largely explains the resistance profiles found in isolates from different sources in 15 countries.

Linalool Reduces Virulence and Tolerance to Adverse Conditions of Listeria monocytogenes

Listeria monocytogenes, a foodborne pathogen causing listeriosis, poses substantial societal, economic, and public health challenges due to its resistance, persistence, and biofilm formation in the food industry. Exploring subinhibitory concentrations of compounds to target virulence inhibition and increase susceptibility to adverse conditions presents a promising strategy to mitigate its impact of L. monocytogenes and unveils new potential applications. Thus, this study aims to explore the effect of linalool on virulence factors of L. monocytogenes and potential use in the reduction in its tolerance to stressful conditions. This action was analysed considering the use of two sub-inhibitory concentrations of linalool, 0.312 and 0.625 mg/mL. We found that even with the lowest tested concentrations, a 65% inhibition of violacein production by Chromobacterium violaceum, 55% inhibition in biofilm formation by L. monocytogenes and 62% reduction on haemolysis caused by this bacterium were observed. In addition to its impact on virulence factors, linalool diminished the tolerance to osmotic stress (up to 4.3 log reduction after 24 h with 12% NaCl), as well as to high (up to 3.8 log reduction after 15 min at 55 °C) and low temperatures (up to 4.6 log reduction after 84 days with 12% NaCl at 4 °C). Thus, this study paves the way to further investigation into the potential utilization of linalool to mitigate the threat posed by L. monocytogenes in the field of food safety and public health.

Comparative genomics reveals high genetic similarity among strains of Salmonella enterica serovar Infantis isolated from multiple sources in Brazil

Background

Salmonella enterica serovar Infantis (Salmonella Infantis) is a zoonotic, ubiquitous and foodborne pathogen of worldwide distribution. Despite Brazil's relevance as a major meat exporter, few studies were conducted to characterize strains of this serovar by genomic analyses in this country. Therefore, this study aimed to assess the diversity of 80 Salmonella Infantis strains isolated from veterinary, food and human sources in Brazil between 2013 and 2018 by comparative genomic analyses. Additional genomes of non-Brazilian countries (n = 18) were included for comparison purposes in some analyses.

Methods

Analyses of whole-genome multi-locus sequence typing (wgMLST), using PGAdb-builder, and of fragmented genomes, using Gegenees, were conducted to compare the 80 Brazilian strains to the 18 non-Brazilian genomes. Pangenome analyses and calculations were performed for all Salmonella Infantis genomes analyzed. The presence of prophages was determined using PHASTER for the 80 Brazilian strains. The genome plasticity using BLAST Ring Image Generator (BRIG) and gene synteny using Mauve were evaluated for 20 selected Salmonella Infantis genomes from Brazil and ten from non-Brazilian countries. Unique orthologous protein clusters were searched in ten selected Salmonella Infantis genomes from Brazil and ten from non-Brazilian countries.

Results

wgMLST and Gegenees showed a high genomic similarity among some Brazilian Salmonella Infantis genomes, and also the correlation of some clusters with non-Brazilian genomes. Gegenees also showed an overall similarity >91% among all Salmonella Infantis genomes. Pangenome calculations revealed an open pangenome for all Salmonella Infantis subsets analyzed and a high gene content in the core genomes. Fifteen types of prophages were detected among 97.5% of the Brazilian strains. BRIG and Mauve demonstrated a high structural similarity among the Brazilian and non-Brazilian isolates. Unique orthologous protein clusters related to biological processes, molecular functions, and cellular components were detected among Brazilian and non-Brazilian genomes.

Conclusion

The results presented using different genomic approaches emphasized the significant genomic similarity among Brazilian Salmonella Infantis genomes analyzed, suggesting wide distribution of closely related genotypes among diverse sources in Brazil. The data generated contributed to novel information regarding the genomic diversity of Brazilian and non-Brazilian Salmonella Infantis in comparison. The different genetically related subtypes of Salmonella Infantis from Brazil can either occur exclusively within the country, or also in other countries, suggesting that some exportation of the Brazilian genotypes may have already occurred.