Search Results (547)

Buffalo meat is widely consumed in Egypt; however, it may pose serious food safety risks due to microbial contamination during handling, preparation, and processing. This study investigated the prevalence and characterization of multidrug-resistant (MDR) enterotoxigenic Staphylococcus aureus in raw ground buffalo meat and ready-to-eat (RTE) kofta and liver sandwiches marketed in Mansoura, Egypt. S. aureus was detected in 62% (62/100) of raw buffalo ground meat, 41% (41/100) of RTE kofta, and 60% (60/100) of RTE liver samples, with an overall prevalence of 54.3% (163/300). All 660 isolates were confirmed as S. aureus via nuc gene detection, among which 46.8% (309/660) were mecA-positive and verified as methicillin-resistant (MRSA), and 21.8% (144/660) were vanA-positive and verified as vancomycin-resistant (VRSA). Enterotoxigenic strains were identified in 42.7% (282/660) of isolates, with the sea gene being most prevalent (67.7%; 191/282), followed by seb (58.2%; 164/282) and sec (39.7%; 112/282). The highest frequency of enterotoxigenic strains occurred in raw ground meat (47.2%), followed by kofta (45.1%) and liver (36%). Antimicrobial susceptibility testing against 15 antibiotics revealed that 7.6% (50/660) of isolates were extensively drug-resistant (XDR) with a MAR index of 0.9, while 82.9% (547/660) were MDR with MAR values between 0.3 and 0.7, indicating exposure to environments of intensive antibiotic use. The present findings highlight a high contamination level of buffalo meat products with MDR enterotoxigenic MRSA and VRSA, representing a significant public health hazard. Implementation of strict hygiene measures, wise antibiotic usage, and continuous surveillance is essential to control their dissemination through the food chain. Full article

Staphylococcus aureus is a major bacterial pathogen that can cause clinical infections and foodborne illnesses through the production of 25 exotoxin types. The most frequently implicated toxins in food poisoning outbreaks are Staphylococcal enterotoxins type A–E (SEA-SEE), which are the first enterotoxins discovered. While in vitro detection methods are available to identify the presence of enterotoxins, they cannot distinguish between biologically active and inactive forms of the toxins. Detection of biologically active enterotoxins currently relies on in vivo testing, using the emetic response in kittens or monkeys. Here, we show the development of an in vitro assay to detect the active forms of SEB, a potential biological warfare agent and leading cause of food poisoning, and SEC1, a frequent cause of staphylococcal food poisoning. The novel assay involves the implementation of a genetically engineered Jurkat T-cell line expressing TCR Vβ3, resulting in a dose response of IL-2 production when exposed to active toxin. We also show that at a concentration of 100 ng/mL, the biological activity of SEB is significantly decreased at temperatures over 70 °C, while pasteurization at 63 °C only slightly reduces the biological activity of the toxin. Our studies provide an alternative method to animal testing to determine the presence of active toxins and provide possible inactivation methods of the toxins. Full article

Eosinophilic chronic rhinosinusitis (eCRS) is an upper respiratory condition frequently associated with olfactory dysfunction (OD). Despite its high prevalence, the mechanisms underlying OD remain poorly understood. Several eCRS models have been described, but their olfactory phenotypes are poorly characterized. In this study, we compared two of the most frequently used mouse models of eCRS in order to standardize in vivo research on eCRS-related OD. Male and female mice were challenged with ovalbumin (OVA) combined with Staphylococcus aureus enterotoxin B (SEB) over a 13-week protocol or with OVA combined with Aspergillus oryzae protease (AP) for 6 or 12 weeks. Olfactory function was assessed using the buried food test and habituation/dishabituation test. After sacrifice, the integrity and inflammation of the olfactory epithelium were assessed on coronal skull sections by (immuno)histology, including sex as a biological variable. Both models exhibited impaired olfactory function, reduced olfactory epithelium surface area and thickness, and eosinophil infiltration of the olfactory mucosa. The OVA-AP model showed additional presence of neutrophils in the olfactory mucosa, suggesting a mixed inflammatory response. No functional or histological difference was detected between male and female mice, except for epithelial thickness in OVA-SEB control mice. Overall, both murine models are suitable for mechanistic studies of OD in eCRS, with the AP-12-week model displaying the most pronounced inflammation. Full article

Background/Objectives: Post-weaning diarrhea remains a major challenge in pig production worldwide. Enterotoxigenic Escherichia coli (ETEC) encoding fimbriae of the F4 type and producing the heat-stable enterotoxin, STb, are one of the important causes of this disease. The aim of the current study was to evaluate whether vaccination of pregnant sows with a novel capsid virus-like particle (cVLP)-based vaccine against F4 and STb (cVLP-FaeG/cVLP-STb) could enhance performance in piglets born after such vaccinated sows. Methods: A field trial was conducted in a commercial sow-to-finisher pig herd. Thirty-five sows were vaccinated twice with the cVLP-FaeG/cVLP-STb vaccine prior to farrowing, while thirty-five control sows were vaccinated twice with commercial vaccines normally used in the herd. Piglets were followed until eight weeks post-weaning to assess antibody responses, diarrhea and treatment incidences, pathogen shedding, and growth performance. Results: Piglets born from immunized sows receiving the cVLP vaccine showed significantly higher serum antibody levels against ETEC F4 throughout the post-weaning period (p ≤ 0.021). The frequency of pathogen detection was similar between groups, while piglets in the cVLP group exhibited significantly lower diarrhea scores at week 6 (p = 0.047), showed a trend of requiring fewer treatments (p = 0.06) and had significantly higher final body weight (p = 0.048). In addition, the cVLP group showed a significantly greater average daily gain over the study period (p = 0.037). Conclusion: Sow immunization with the cVLP vaccine enhanced passive immune protection of piglets, resulting in reduced antimicrobial treatment 2 weeks post-weaning and improved growth performance. Full article

Staphylococcus aureus is a major cause of foodborne intoxication through the production of heat-stable enterotoxins (SEs) and is also an important opportunistic pathogen of humans and livestock. Meat and meat products are major vehicles for this pathogen because their protein-rich composition supports bacterial growth and toxin production. However, the combined effects of temperature and nutrient composition on S. aureus growth and virulence expression under food-relevant conditions remain unclear. In this study, we investigated the interactive effects of temperature and nutritional context on the growth and virulence-associated phenotypes under model food-relevant environments with the reference strain S. aureus FRI-S6. Bacterial growth, biofilm formation, staphylococcal enterotoxins A and B (SEA, SEB), and hemolytic activity were evaluated at 25 °C and 37 °C in brain heart infusion (BHI) medium supplemented with NaCl, glucose, or tryptone to simulate diverse food-relevant conditions. Growth was generally faster at 37 °C, whereas glucose-supplemented cultures at 25 °C reached higher cell densities during prolonged incubation. Biofilm formation increased at 37 °C in BHI and glucose conditions. SEA production was enhanced at 37 °C under NaCl and tryptone, but at 25 °C in glucose-rich conditions. In contrast, SEB production and hemolytic activity were consistently higher at 37 °C, particularly in the presence of tryptone and glucose. These findings demonstrate the strong interaction between temperature and nutrient composition in shaping S. aureus virulence in food environments and provide important insights for food safety risk assessment and highlight practical implications for controlling enterotoxin production in meat products and other foods during storage and processing. Full article

In this review, the virulence factors involved in enterotoxigenic Escherichia coli (ETEC) colonization and pathogenesis are analyzed, with an emphasis on colonization factors, enterotoxins and antigenic diversity as central challenges in vaccine development. ETEC remains a major cause of diarrhea worldwide, particularly in vulnerable populations. Despite extensive research, no broadly protective licensed vaccines are available largely because of antigenic heterogeneity and the limited understanding of immune correlates of protection. We identified critical knowledge gaps in antigen prioritization and host–pathogen interactions and translational limitations that have hindered vaccine success. We critically evaluated emerging platforms (including mRNA vaccines, nanoparticles, multiepitope strategies, and reverse vaccinology) for their potential to overcome variability and increase immunogenicity. We examined the roles of ecological environmental reservoirs associated with human and animal systems, in addition to antimicrobial pressure, in shaping ETEC evolution and vaccine effectiveness within a One Health framework; moreover, we propose an integrated approach that links genomic surveillance-based vaccine ecology and next-generation vaccine technologies to support adaptive immunogen design. This review provides actionable recommendations for the development of broadly protective and translationally viable ETEC vaccines from the One Health perspective. Full article

Staphylococcus aureus nasal carriage contributes to asymptomatic transmission in both community and healthcare settings. This study aimed to characterize S. aureus strains isolated from students of the Pomeranian Medical University in Szczecin, Poland, using phenotypic and genotypic methods. A total of 175 S. aureus strains were isolated from the nasal vestibules of 800 students between 2014 and 2015. Species identification and antimicrobial susceptibility testing were performed using standard microbiological methods, while virulence-associated genes and agr groups were analyzed using Single-PCR and Multiplex-PCR assays. Genotypic diversity was assessed by pulsed-field gel electrophoresis (PFGE). The prevalence of S. aureus nasal carriage among students was 21.9% and did not differ according to faculty or year of study. Most isolates (84.0%) were susceptible to all tested antibiotics, and no methicillin-resistant S. aureus (MRSA) strains were detected. All strains carried the hla gene, whereas hld and hlg were identified in 93.7% and 93.1% of isolates, respectively. In addition, the tst gene was detected in 22.3% of strains, while the lukS-PV/lukF-PV genes were identified in only one isolate (0.6%). The most prevalent enterotoxin genes were sep (17.1%) and sea (13.7%), whereas genes of the egc cluster, including seg, sei, and seo, were detected in 53.7% of isolates. Significant associations were observed between specific egc gene combinations and superantigen gene profiles, including increased frequencies of sec, sel, and tst genes (p < 0.001). The predominant agr type was agr-1 (49.7%), followed by agr-3 (28.6%) and agr-2 (20.0%). Strains carrying agr-1 more frequently harbored the g i m n o cluster as well as the sec, sel, and sep genes, whereas agr-3-positive isolates were significantly associated with the g i m o u and g i o u clusters and with the presence of tst, sea, and seh genes (p < 0.05). PFGE analysis demonstrated substantial genetic heterogeneity among the isolates, with no evidence of a predominant clonal lineage. These findings indicate a heterogeneous, non-epidemic population structure of S. aureus strains circulating among university students and highlight the considerable diversity and interrelationships of virulence-associated genetic profiles within this population. Full article

Most infectious pathogens enter the host through mucosal surfaces, yet conventional injectable vaccines primarily induce systemic immunity without eliciting robust secretory immunoglobulin A (SIgA) responses at mucosal sites. The COVID-19 pandemic highlighted this limitation, as intramuscular mRNA vaccines failed to establish durable mucosal immunity in the upper respiratory tract. This review covers recent progress in mucosal vaccine development. We first discuss the organization of the mucosal immune system, focusing on SIgA induction, tissue-resident memory T (${\mathrm{T}}_{\mathrm{RM}}$) cells, and resident memory B (${\mathrm{B}}_{\mathrm{RM}}$) cells. We then examine mucosal adjuvants, from cholera toxin and heat-labile enterotoxin derivatives to stimulator of interferon gene (STING) agonists and a strategy to enhance alum adjuvanticity through neutrophil elastase inhibition. Delivery routes including intranasal, oral, and sublingual administration are reviewed alongside viral vectors, nanoparticles, mRNA-lipid nanoparticles, virus-like particles, and engineered bacterial platforms. The roles of innate immune cells, T helper cell subsets, and the microbiota in shaping vaccine responses are discussed. Finally, we survey licensed mucosal vaccines and the COVID-19 mucosal vaccine pipeline, analyze persistent barriers to clinical translation including the absence of validated mucosal correlates of protection, and outline future directions for thermostable formulations and systems biology-driven vaccine design. Full article

Methicillin-resistant Staphylococcus aureus (MRSA) is a major antimicrobial-resistant pathogen affecting both human and animal health. Although historically associated with healthcare settings, MRSA is now established in livestock production and throughout the production chain. Its detection in animals, food products, and processing environments reflects the complex ecology of antimicrobial resistance (AMR) in modern food systems. This narrative review synthesizes current evidence on the molecular basis of methicillin resistance and multidrug resistance determinants, as well as the epidemiology of MRSA in food-associated settings. Particular emphasis is placed on its occurrence in animal-derived foods and key reservoirs within farms, slaughterhouses, and processing environments. Livestock-associated populations are dominated by clonal complex CC398. In contrast, CC9 is prevalent in pig production systems in Asia, while CC5-related lineages occur at the human and animal interface. MRSA has been detected in retail meat and animal-derived foods at low but measurable prevalence, indicating contamination during slaughter and processing. Virulence determinants include staphylococcal enterotoxins linked to food poisoning and Panton–Valentine leukocidin associated with severe infections. Biofilm formation and adhesins further support persistence and colonization. Epidemiological and molecular evidence indicates that livestock, processing environments, and food-contact surfaces act as interconnected reservoirs sustaining MRSA circulation. Human exposure occurs primarily through occupational contact and environmental pathways, whereas foodborne transmission appears less common. Effective control requires integrated surveillance, responsible antimicrobial use in livestock production, and strict hygiene practices throughout the production chain within a One Health framework. Full article

Cancer remains one of the leading causes of morbidity and mortality worldwide, and despite major advances in surgery, chemotherapy, radiotherapy, and immunotherapy, important therapeutic limitations persist, including systemic toxicity, therapeutic resistance, and poor drug penetration into hypoxic tumor regions. These challenges have renewed interest in alternative biological strategies, particularly the use of bacteria and bacterial toxins as antitumor agents. Certain bacterial species possess intrinsic tumor-targeting properties, including the ability to selectively colonize hypoxic and necrotic regions of solid tumors that are poorly accessible to conventional therapies. This review provides a comprehensive analysis of the mechanisms underlying bacteria-mediated anticancer activity, including selective tumor colonization, direct oncolysis, immune activation, and toxin-mediated cytotoxicity. Both obligate anaerobes (e.g., Clostridium and Bifidobacterium) and facultative anaerobes (e.g., Salmonella, Escherichia coli, and Listeria monocytogenes) are examined for their tumor-targeting potential. In addition, we discuss the oncological applications of several bacterial toxins and toxin-derived therapeutic constructs, including Cytolysin A (ClyA), Clostridium difficile toxin B (TcdB), diphtheria toxin, Pseudomonas aeruginosa exotoxin A, and Clostridium perfringens enterotoxin (CPE). Emerging strategies such as recombinant immunotoxins and bacterial-directed enzyme prodrug therapy (BDEPT) are also reviewed. Finally, current translational challenges, including pharmacokinetic limitations, immune clearance, and biosafety considerations, are analyzed, highlighting future directions for integrating bacteria-based platforms into next-generation cancer therapies. This approach reflects the growing interest in microbial strategies for oncology and underscores the potential of bacteria and their toxins as innovative tools in the development of targeted anticancer therapies. Full article

Raw milk dairy products, an integral part of Italian food heritage, are the primary products of small-scale farms in mountain regions where pasture is seasonal. While raw milk dairy products offer potential health benefits, their physicochemical properties make them susceptible to foodborne pathogens. Long-term surveillance of these products is essential to safeguard consumer health. Here, we present a fourteen-year microbiological surveillance of raw milk dairy products and intermediate matrices from northeastern Italy’s alpine areas, analyzing coagulase-positive Staphylococci (CPS), β-glucuronidase-positive Escherichia coli, Listeria monocytogenes, and Shiga toxin-producing E. coli (STEC). The most frequently detected pathogens were CPS and β-glucuronidase-positive E. coli, with up to 19.6% and 51.7% of samples exceeding regulatory limits, respectively. Butter, curd, and fresh cream were the most contaminated matrices. Detection rates of staphylococcal enterotoxins, L. monocytogenes, and STEC aligned with European detection averages (6.7%, 2.6%, and 2.1%, respectively). These findings underscore the necessity of Good Hygiene and Management Practices, together with regular microbiological monitoring to mitigate contamination risks, supporting the safety and quality of traditional raw milk dairy products in alpine regions. Full article

Necrotizing enteritis (NE) is an important intestinal disease threatening the poultry farming industry, and the ban on antibiotic growth promoters has created an urgent demand for safe and effective NE vaccines. Recombinant attenuated Salmonella vectors (RASVs) administered orally can induce mucosal immune responses against delivered antigens, thus showing great potential to elicit protective immunity against NE. The EntB protein is a newly discovered putative enterotoxin of Clostridium perfringens (C. perfringens). Bioinformatic predictions in this study revealed that EntB contains nineteen potential antigenic epitopes, two functional domains (NlpC and YgiM), and interacts with ten proteins, supporting its potential as a target antigen for NE vaccines. To optimize the immunogenicity of EntB-based vaccines, we constructed a novel recombinant attenuated Salmonella Enteritidis (S. Enteritidis) vector rSC0169 harboring a rhamnose-regulated delayed attenuation system, which was then used to deliver EntB to generate the recombinant strain rSC0169(pS-EntB). This system enhanced the immunogenicity of the Salmonella vector rSC0169 and further elicited robust mucosal immune responses against EntB, as well as humoral and cellular immune responses. Compared with the control strain rSC0169(pS0018), rSC0169(pS-EntB) candidate vaccine strain significantly alleviated NE symptoms, increased the intestinal villus height/crypt depth (VH/CD) ratio, upregulated tight junction protein expression, and reduced excessive pro-inflammatory cytokine production. In conclusion, this study provides a promising NE candidate vaccine and offers a valuable strategy for developing vaccines against other intestinal bacterial diseases. Full article

Foodborne diseases represent a major public health concern, particularly those associated with dairy products contaminated with Staphylococcus aureus, a pathogen capable of producing heat-stable enterotoxins. This study evaluated the potential of native lactic acid bacteria (LAB) isolated from artisanal kefir grains as natural biocontrol agents in fermented dairy foods. Kefir grains obtained from three artisanal producers were microbiologically characterized, revealing LAB as the dominant group and the absence of Enterobacteriaceae. Strains belonging mainly to the genera Lactobacillus sensu lato, Leuconostoc, and Pediococcus were isolated and exhibited differentiated metabolic profiles. Safety assessment showed no hemolytic activity and an overall susceptibility to clinically relevant antibiotics, although genus-dependent intrinsic resistance patterns were observed. Several strains displayed enzymatic activities related to carbohydrate digestion and high tolerance to simulated gastrointestinal conditions, with survival rates exceeding 90% during both gastric and intestinal phases. Neutralized cell-free supernatant (CFS) demonstrated differential inhibitory activity, with significant antagonism of S. aureus and E. coli, comparable to those of commercial reference strains. In a yogurt model system stored at 4 °C, selected Lactobacillus and Pediococcus strains induced a progressive and significant reduction in S. aureus populations, achieving complete elimination to undetectable levels in shorter times than commercial probiotic strains. Overall, these results demonstrate that native LAB from artisanal kefir grains exhibit an adequate safety and functional profile, together with strong antagonistic activity, supporting their potential application as natural protective cultures to improve the food hygiene of fermented dairy products. Full article

Background/Objectives: Staphylococcus aureus (S. aureus) intramammary infection remains a major global dairy problem due to its contagious nature, its ability to persist and colonize teat/skin and mucosal niches, and the often-limited bacteriological cure achieved with antimicrobial therapy. Beyond udder health, it is relevant to public health because it can enter raw milk chains and serve as a reservoir for antimicrobial resistance determinants that may circulate between dairy animals and humans. Methods: We assessed S. aureus’ ecology in raw ewe milk from 75 sheep farms in Epirus (Greece) by sampling clinically healthy controls (group A) and clinical mastitis cases pre-treatment (group B), followed by resampling at the first post-withdrawal milking after penicillin/streptomycin treatment (group C1—therapeutic protocol 1), oxytetracycline treatment (group C2—therapeutic protocol 2), or enrofloxacin treatment (group C3—therapeutic protocol 3). Results: S. aureus detection was high and comparable across groups (A 23.0%, B 22.0–30.0%, C 20.0–22.0%), and paired analyses showed no significant pre–post shifts in detection/burden within therapeutic protocols (all p > 0.05). Nevertheless, persistence remained evident. The chromosomal gene mecA was detected in S. aureus strains in all groups, ranging from 13.6% in controls to 54.5% post-withdrawal in group C1, and was also present in the pre-treatment group. In paired sampling animals, mecA was mostly stable, with rare emergence or loss. Across antibiotic classes, within-animal resistance transitions were generally uncommon and non-significant (p > 0.05); β-lactam resistance was fully stable (p = 1.00). Descriptively, resistance to protein synthesis inhibitors tended to decline after therapy in protocol 1 and protocol 3, while protocol 3 showed post-treatment gains in fluoroquinolone resistance. By contrast, virulence-associated phenotype traits shifted after therapy: enterotoxigenicity increased post-withdrawal (especially in the C3 group), Staphylococcal Enterotoxin A (SEA) and Staphylococcal Enterotoxin B (SEB) appeared only post-therapy, Staphylococcal Enterotoxin D (SED) increased significantly in paired isolates (p = 0.002), and strong biofilm adherence increased (in C3, p = 1.5 × 10⁻⁵). Conclusions: The detection of S. aureus after therapy suggests that one possibility is that antimicrobial exposure may select for, or otherwise reshape, the residual intramammary population, rather than reliably eliminating it—an outcome that remains clinically relevant for udder health. Moreover, the persistence of mecA/methicillin-resistant Staphylococcus aureus (MRSA)-compatible profiles indicates that milk released to the food chain after withdrawal compliance may still harbor S. aureus with enhanced preservation capacity and significant food safety relevance. Full article

Human organoids and organ-on-chip/microphysiological systems (OoC/MPS) are increasingly used as new-approach methodologies for biotoxin assessment. They retain human-relevant tissue organization and enable interpretable analysis of exposure geometry, barrier transport, perfusion, and (when needed) multi-organ coupling. In this review, we synthesize primary evidence across major toxin classes, including bacterial enterotoxins (e.g., cholera toxin, heat-stable enterotoxins, Shiga toxins), mycotoxins (e.g., aflatoxin B1, ochratoxin A, deoxynivalenol), and algal/cyanobacterial toxins (e.g., saxitoxin, domoic acid, microcystins, biliatresone). We emphasize studies that clearly define toxin identity and exposure context and that demonstrate mechanism-critical model competencies under assay conditions. We highlight decision-informative functional endpoints that align with the dominant pathophysiology. These include cystic fibrosis transmembrane conductance regulator (CFTR)-dependent secretion in human enteroids/colonoids, transporter-linked proximal tubular injury in kidney MPS, gut–kidney axis injury from Shiga toxin-producing E. coli in microfluidic systems, and multi-electrode array (MEA) network readouts in human 3D neural tissues. We then summarize best practices that improve cross-study comparability. These include reporting delivered versus nominal exposure, assessing recovery/mass balance and device/material interactions, applying proportional biological qualification (polarity, transporter/enzymatic competence, functional stability), defining a minimal comparable endpoint core, and preserving QIVIVE readiness in reporting. Finally, we outline near-term priorities for the field, including chronic low-dose and mixture designs, harmonized reference panels and acceptance criteria, and fit-for-purpose escalation to coupled OoC/MPS only when perfusion or organ–organ coupling is expected to change the interpretation. Full article