Search Results (152)

Salmonella infects a wide range of hosts, causing gastroenteritis or systemic infection in humans and animals, highlighting the urgent need for a deeper understanding of its pathogenesis. SpvC, a critical virulence determinant of salmonella, facilitates bacterial dissemination. Gasdermin D (GSDMD) is the only gasdermin known to protect mice against acute Salmonella enteritis. Our preliminary findings indicated that SpvC counteracts GSDMD-mediated antibacterial effects to enhance bacterial dissemination, although its functional relevance to epithelial-derived GSDMD and the underlying mechanisms remain unclear. To address this, Gsdmd^−/− C57BL/6J and wild-type mice were infected with Salmonella Typhimurium (S. Typhimurium) wild-type strain and spvC deletion mutant. Our results demonstrate that SpvC compromises intestinal epithelial barrier integrity, overcoming GSDMD-mediated protection against systemic infection. Specifically, through bioinformatics analysis, LC-MS/MS, and in vivo experiments with Caco-2 cell monolayers and site-directed spvC mutants, we identified SEC23B as a novel target of SpvC. This interaction disrupts the intestinal epithelial barrier through the autophagy–pyroptosis pathway. This study identifies SEC23B as a unique cellular target of SpvC involved in GSDMD activation during S. Typhimurium systemic infection. It also reveals a novel mechanism by which Salmonella evades host defense mechanisms. Full article

Acute non-typhoidal salmonellosis (NTS) from non-typhoidal Salmonella remains a major cause of foodborne bacterial gastroenteritis, and non-antibiotic interventions are needed to combat multidrug-resistant NTS. Bioactive compounds from edible mushroom extracts have shown both direct and indirect antimicrobial activities on Salmonella. However, the variation in their antimicrobial activity could be due to several factors, including the extract’s form and strain. This study investigated the ability of crude exopolysaccharides (EPs) produced by Schizophyllum commune CMU-01 to limit Salmonella infection in vitro. Agar well diffusion and liquid culture were used to determine the direct anti-Salmonella activity of S. commune EPs, while the gentamicin protection assay and qPCR in human gut epithelium (T84 cells) and murine macrophages (RAW264.7 cells) were used to investigate its indirect (immunomodulatory) activity. Our data reveal that S. commune EPs do not confer the direct antimicrobial property against Salmonella. However, its immunomodulatory activity in two important components of the gut innate defense (the gut epithelium and macrophages) against Salmonella infection has been demonstrated. S. commune EPs reduce Salmonella gut epithelial cell invasion and activate macrophages toward M1 (inflammatory phenotype) polarization, resulting in the reduction in intracellular Salmonella burdens. Alterations in proinflammatory and anti-inflammatory cytokine gene expressions were also detected in S. commune EPs-treated cells. These findings suggest that the host innate immune response to fungal exopolysaccharides derived from S. commune CMU-01 favors reducing Salmonella proliferation within host cells by altering the expression levels of proinflammatory cytokines. Full article

Campylobacter is the primary bacterial cause of foodborne gastroenteritis globally. While international standards recommend a tiered approach for detection, emerging evidence suggests that selective protocols may introduce species-specific recovery biases. This systematic review and meta-analysis evaluated the diagnostic performance of established culture-based detection protocols across diverse food matrices. Following PRISMA 2020 guidelines, we searched multiple databases for studies reporting 2 × 2 diagnostic accuracy data through October 2024. Ten studies comprising 43 method comparisons and 4599 samples met the inclusion criteria. The overall pooled sensitivity was 95.8% (95% CI: 93.6–97.4%), and the specificity was 90.2% (95% CI: 86.8–92.9%). Even with a limited number of comparisons (n = 2), direct culture demonstrated high diagnostic sensitivity (99.1%) and significantly faster turnaround times. Crucially, selective enrichment exhibited a profound species-specific bias: C. jejuni showed 59.4 percent lower recovery than C. coli in Bolton broth, likely due to differential polymyxin B susceptibility. These findings highlight the importance of context-dependent method selection within the ISO 10272-1:2017 framework, suggesting that direct culture (Procedure C) should be prioritized for high-contamination matrices to ensure unbiased recovery of C. jejuni. Large-scale multicenter validation is warranted to confirm these exploratory findings for direct culture. Full article

Listeria monocytogenes (LM) is a major foodborne pathogen causing illnesses ranging from gastroenteritis to severe systemic infections. The key virulence factors include bacterial motility, hemolysin and lecithinase production, and invasion of host tissues. This study investigated the anti-virulence effects of cannabidiol (CBD), the main non-psychoactive compound in Cannabis sativa, against LM. The minimum inhibitory concentration (MIC, 2289 μM; 719.8 µg/mL) and sub-inhibitory concentration (SIC, 11.92 μM; 3.75 µg/mL) of CBD were determined for LM strains Scott A and ATCC 19115. Cultures were treated with SIC, 6× SIC, 1/4× MIC, and MIC to assess effects on motility, hemolysin and lecithinase production, and adhesion and invasion of human intestinal (Caco-2) and brain endothelial (HBMEC) cells, alongside virulence gene expression by RT-qPCR. Cannabidiol’s efficacy was also determined using a Galleria mellonella larval infection model at SIC and 6× SIC. Cannabidiol at 6× SIC significantly reduced motility, toxin production, and host cell adhesion and invasion (p < 0.05). RT-qPCR revealed downregulation of key virulence genes, including prfA, hly, plcA, plcB, iap, motA, motB, actA, inlA, and inlB. In vivo, CBD enhanced larval survival in a dose-dependent manner and cytotoxicity was observed at concentrations above 33.75 µg/mL. These results indicate that CBD, at non-bactericidal levels, effectively suppresses multiple virulence mechanisms in LM, highlighting its potential as a novel anti-virulence agent for food safety and therapeutic applications. Full article

Listeria monocytogenes is a foodborne pathogen of significant concern. While it typically causes mild, self-limiting gastroenteritis, it poses a much higher threat to immunocompromised individuals and pregnant women, where it may lead to miscarriage. Numerous outbreaks have been linked to ready-to-eat foods. Although heat treatment is commonly used for microbial decontamination, it is unsuitable for fresh produce such as fruits and vegetables. Other physical (e.g., UV, gamma irradiation) and chemical (e.g., NaOCl, ozone) methods can compromise sensory qualities or face limited consumer acceptance. Photodynamic Inactivation (PDI) has emerged as a promising alternative, particularly when using natural photosensitizers. Because PDI efficacy depends on photosensitizer diffusion, there is a need to further explore how different and complex fruit surface structures may influence its performance. Three fruit models were therefore selected to represent distinct surface textures and were evaluated in situ: apples (smooth), strawberries (irregular), and kiwis (fuzzy and hairy surface). The influence of contamination order was also evaluated, as this factor is highly relevant to real-world supply-chain scenarios but has been largely overlooked in prior research. Additionally, the study investigated how the order of contamination affected the decontamination outcome. Sodium-magnesium-chlorophyllin (Na-Mg-Chl), an approved food additive (E140), was used as photosensitizer. Fruits were cut into 1 cm² squares and inoculated with L. monocytogenes. A 100 µM Na-Mg-Chl solution was applied either before or after bacterial inoculation. All samples were then illuminated using a 395 nm LED (radiant exposure 15 J/cm²). When L. monocytogenes was applied first, followed by the addition of Na-Mg-Chl, a 5.96 log reduction was observed in apples, a 5.71 log reduction in strawberries, and a 6.02 log reduction in kiwis. Conversely, when Na-Mg-Chl was applied prior to bacterial deposition, apples showed a 5.61 log reduction, strawberries demonstrated a 6.34 log reduction, and kiwis achieved the highest inactivation, at 6.74 log units. These results indicate that PDI consistently achieved substantial bacterial reductions across all fruit types, regardless of surface characteristics or application order. This supports PDI as a powerful method for fruit surface decontamination, reducing public health risks and economic losses while preserving product quality and consumer confidence. Full article

Background: Rotavirus gastroenteritis (RVGE) remains a leading cause of severe infant diarrhea worldwide, with growing evidence supporting the role of the gut microbiome in modulating the disease. However, the interplay between early-life demographic factors, the gut microbiome, and their combined impact on RVGE clinical severity remains inadequately characterized, particularly in specific geographic populations. Aim: We aimed to investigate how demographic determinants shape gut microbiome composition and function in RVGE and how these features relate to clinical severity. Methods: In our comprehensive case–control study of 165 infants (120 RVGE cases and 45 healthy controls, aged 0–12 months), we utilized 16S rRNA sequencing combined with advanced statistical modeling and machine learning to investigate how demographic factors influence microbiome composition and clinical outcomes. Results: RVGE cases exhibited significantly reduced bacterial diversity (Kruskal–Wallis, Static = 14.85, p < 0.001) and distinct patterns, with community structure most strongly associated with dehydration severity (PERMANOVA; R² = 0.15, p < 0.001). Substantial taxonomic alterations were identified characterized by depletion of beneficial commensals including Akkermansia (LDA score = 3.8, p < 0.001), Faecalibacterium (Random Forest AUC = 0.82, p < 0.001), and Bifidobacterium (r = −0.42 with breastfeeding, p < 0.001), alongside enrichment of inflammation-associated taxa such as Escherichia-Shigella (WBC; r = 0.49, p < 0.001, and CRP; r = 0.56, p < 0.001), Streptococcus (LDA score = 4.2, p < 0.001), and Staphylococcus. Proteobacteria was the top potential biomarker of severe outcomes (Random Forest AUC = 0.85), with abundance positively correlated with systemic inflammation (CRP: r = 0.51, p = 0.003). Functional predictions revealed increased lipopolysaccharide biosynthesis (ko00540) and reduced butanoate metabolism (ko00650, p < 0.001) in severe disease. Importantly, demographic factors significantly modulated clinical outcomes: cesarean-delivered, formula-fed infants presented the most dysbiotic profiles and experienced 3.2-fold longer hospitalization (95% CI: 1.8–5.6, p < 0.001) than vaginally delivered, breastfed infants did. Conclusions: Collectively, these findings demonstrate that early-life demographic factors potentially shape the gut microbiome composition and function, may influence RVGE severity and recovery trajectories, thus providing candidate biomarkers for risk stratification and identifying targets for microbiota-based interventions. Full article

(1) This study explored Lacticaseibacillus rhamnosus MS27, a newly isolated strain, as a potential probiotic candidate for alleviating the onset and severity of ulcerative colitis (UC). (2) L. rhamnosus MS27 was isolated and subjected to biochemical identification, antibiotic sensitivity testing, and antibacterial activity assessment. Dextran sulfate sodium (DSS) colitis model mice were used to evaluate its alleviating effects. In this study, 16S rRNA microbiome and eukaryotes reference transcriptome analyses were conducted to investigate its impact on intestinal microbial ecology and potential molecular mechanisms. (3) L. rhamnosus MS27 exhibits high acid tolerance at pH 3.23 and maintains a high viable bacterial count for 24 h. It can utilize sucrose, lactose, maltose, inulin, esculin, salicin, and mannitol but not raffinose, and it is sensitive to carbenicillin, erythromycin, tetracycline, chloramphenicol, clindamycin, and penicillin. It effectively increases the abundance of beneficial microbes, particularly Akkermansia, Muribaculaceae, and Limosilactobacillus reuteri (p < 0.05), while significantly reducing microorganisms linked to human pathogens causing diarrhea and gastroenteritis (p < 0.05). Transcriptomic analysis demonstrated that the expression levels of Igkv16-104 and C1qtnf3 were significantly downregulated in the presence of L. rhamnosus MS27 treatment compared to DSS treatment alone (p < 0.05). Further analysis revealed significant differences in genes related to immune functions, antigen presentation, and immune cell markers, indicating potential protein–protein interaction networks, particularly among genes of the major histocompatibility complex (MHC). (4) L. rhamnosus MS27, as a novel strain, demonstrates a significant capacity to alleviate inflammatory phenotypes. L. rhamnosus MS27 exhibits distinctive metabolic characteristics in lactic acid utilization, acetic acid and oleic acid production. Furthermore, it contributes to systemic homeostasis regulation by modulating Turicibacter to link intestinal microbiota composition with host immune function. Full article

Campylobacter spp. remain among the most common pathogens causing acute diarrhea worldwide. Campylobacter jejuni and Campylobacter coli are the main species that cause gastroenteritis. Campylobacteriosis is a food-borne disease, although this Gram-negative bacterium may be transmitted via water-borne outbreaks as well as direct contact with animals, emphasizing its zoonotic potential. Campylobacterisosis does not usually require hospitalization. Antimicrobials are warranted only for patients with severe disease, as well as patients who are at risk for severe disease, such as the elderly, pregnant women or immunocompromised patients. Nonetheless, the irrational use of antibiotics in human and veterinary medicine enhances antimicrobial resistance (AMR). Resistance of Campylobacter spp. to fluoroquinolones, macrolides and tetracyclines is a significant concern to the scientific community. Point mutations, horizontal gene transfer and efflux pumps are the main mechanisms for the development and transmission of AMR in Campylobacter spp. Emerging evidence suggests that climate change may indirectly contribute to the spread of AMR in Campylobacter, particularly through its influence on bacterial ecology, transmission pathways and antibiotic use patterns. Higher temperatures and extreme weather events accelerate bacterial growth, amplify the transfer of AMR genes and magnify disease transmission, including drug-resistant infections. Horizontal gene transfer, especially in the context of biofilm formation, may further perplex the situation. Excessive farming and overuse of antibiotics as growth promoters in animals may also contribute to increased AMR rates. Climate change and AMR are interconnected and pose a significant threat to global public health. Multidisciplinary strategies mitigating both phenomena are crucial in order to contain the spread of Campylobacter-related AMR. The aim of this review is to describe the molecular mechanisms that result in AMR of Campylobacter spp. and underscore the association between climate change and Campylobacteriosis. Novel methods to mitigate Campylobacter-related AMR will also be discussed. Full article

Campylobacter spp. are leading causes of bacterial gastroenteritis globally. Swine are recognized as an important reservoir for this pathogen. The emergence of antimicrobial resistance (AMR) and multidrug resistance (MDR) in Campylobacter is a global health concern. Traditional methods for detecting AMR and MDR, such as phenotypic testing or whole-genome sequencing, are resource-intensive and time-consuming. In the present study, we developed and validated a supervised machine learning model to predict MDR status in Campylobacter isolates from swine, using publicly available phenotypic AMR data collected by NARMS from 2013 to 2023. Resistance profiles for seven antimicrobials were used as predictors, and MDR was defined as resistance to at least one agent in three or more antimicrobial classes. The model was trained on 2013–2019 isolates and externally validated using isolates from 2020, 2021, and 2023. Random Forest showed the highest performance (accuracy = 99.87%, Kappa = 0.9962) among five evaluated algorithms, which achieved high balanced accuracy, sensitivity, and specificity in both training and external validation. Our feature importance analysis identified erythromycin, azithromycin, and clindamycin as the most influential predictors of MDR among Campylobacter isolates from swine. Our temporally validated, interpretable model provides a robust, cost-effective tool for predicting MDR in Campylobacter spp. and supports surveillance and early detection in food animal production systems. Full article

Campylobacter species are considered to be the leading bacterial cause of human gastroenteritis globally. Consumption of undercooked or contaminated food, such as chicken, is the main cause of human campylobacteriosis. Despite this significant zoonotic link, comparative data on virulence determinants in Campylobacter isolates across avian and human sources remain limited. This study aimed to characterize the prevalence and expression of virulence determinants in Campylobacter jejuni and Campylobacter coli isolates from chicken and human sources in Ismailia governorate, Egypt. A total of twenty C. jejuni and C. coli isolates (ten of each species) were screened for 14 virulence genes using PCR. All isolates harbored virB11, iam, racR, and tetO. Chicken isolates exhibited a significantly higher prevalence: C. jejuni (chicken): pldA, dnaJ, flaA (100%), cdtB (80%), ciaB (60%), and wlaN (0%); C. coli (chicken): pldA, dnaJ (100%), flaA (60%), cdtB (60%), ciaB (40%), and wlaN (20%). In contrast, human isolates showed a markedly lower prevalence: C. jejuni (human): dnaJ, flaA, and cdtB (20%); C. coli (human): dnaJ, flaA, and cdtB (40%). Crucially, pldA, ciaB, and wlaN were absent in all human isolates. plda and dnaJ genes showed statistically significant prevalence differences. qPCR revealed a significant upregulation (p < 0.05) of dnaJ, virB11, flaA, and iam in chicken isolates compared to human isolates, with log₂ fold changes of 3.52, 2.84, 2.43, and 1.90 for C. jejuni and 3.06, 2.38, 1.51, and 1.32 for C. coli. Differential expressions of racR, cdtB, and tetO were not significant, with log2 fold changes ranging from −0.51 to 0.14. Ganglioside mimicry genes (Cst11, wlaN, Waac, ggt, and cgtB) and the carbon storage regulator gene (csrA) were absent in all human isolates. These findings underscore the significant variability in virulence gene profiles in chicken and human C. jejuni and C. coli isolates and highlight the importance of molecular characterization in the risk assessment and epidemiological surveillance of Campylobacter infections. Full article

Clinical manifestations of salmonellosis in humans typically include acute gastroenteritis, abdominal pain, diarrhea, nausea, and fever. Diarrhea and anorexia may persist for several days. In some cases, the organisms may invade the intestinal mucosa and cause septicemia, even in the absence of significant gastrointestinal symptoms. Most clinical signs are attributed to hematogenous dissemination of the pathogen. As with other microbial infections, disease severity is influenced by the serotype of the organism, bacterial load, and host susceptibility. Serotyping analysis of Salmonella spp. using the White–Kauffmann–Le Minor scheme remains the gold standard for strain typing. However, this method is expensive, time-consuming, and requires significant expertise and visual interpretation by trained personnel, which is why it is typically restricted to regional or national reference laboratories. In this study, we evaluated a spectroscopic technique coupled with chemometrics and multivariate machine learning algorithms for its ability to discriminate the main Salmonella spp. serogroups in a clinical routine setting. We analyzed 95 isolates of Salmonella that were randomly selected, including four strains of S. Typhi. The I-dOne Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) system (Alifax S.r.l., Polverara, Italy) also shows promising potential for distinguishing Salmonella Typhi within the D serogroup. The I-dOne system enables simultaneous identification of both species and subspecies using the same workflow and instrumentation, thus streamlining the diagnostic process. Full article

Background: Antimicrobial resistance (AMR) is a growing global health threat, with children in low- and middle-income countries bearing a disproportionate burden. Data on resistance patterns and diagnostic practices in pediatric populations remain limited. This study evaluated diagnostic utilization and AMR among children hospitalized with bacterial infections at a national referral hospital in Kenya. Methods: We conducted a retrospective cohort study of pediatric inpatients (0–12 years) admitted with bacterial infections between 2017 and 2021. Patient records were identified using ICD-10 codes and reviewed for diagnostic testing and antimicrobial susceptibility. Descriptive statistics were conducted to show infection counts, diagnostic testing, and resistance outcomes. Results: Among 1608 patients, 1009/1608 (63%) were infants under one year. Culture was conducted in 640/1608 (40%) and antimicrobial sensitivity testing in 111/640 (17%) patients. Gastroenteritis (46%) was the most common infection and blood the most frequently collected specimen (31%). Of 1039 cultured specimens, 896/1039 (86%) showed no growth. The most commonly isolated organisms were Klebsiella pneumoniae 19/128 (15%), Staphylococcus epidermidis (13%, 17/128), and Enterococcus faecium (13%, 16/128). Notably, K. pneumoniae showed 100% resistance to third-generation cephalosporins, suggestive of ESBL production. Among the tested samples, 92/128 (72%) had MDROs, and 26/92 (28%) were extensively drug-resistant (XDR). Among the patients tested, 84/111 (76%) had MDROs, of which 25/84 (30%) were XDR. Children under 5 years had higher odds (OR = 5.84, 95% CI: 1.17-38.21) of having MDRO infections, as well as those with multiple admissions (OR = 3.77, 95% CI: 1.06–20.34). Further, increasing age was inversely associated with MDRO presence. The odds of MDRO infection decreased by 24% for every year increase in age (aOR = 0.76; 95% CI: 0.60–0.93; p = 0.006). Conclusions: The findings highlight the limited diagnostic use and a high burden of MDROs and XDR infections in hospitalized children. Strengthening diagnostic capacity and pediatric antimicrobial stewardship is urgently needed in such settings. Full article

Objectives: Norovirus outbreaks occur in densely populated environments, such as long-term care facilities, hospitals, and schools. On 22 October 2022, an outbreak of acute gastroenteritis was reported at a kindergarten in Korea. An epidemiologic investigation was conducted to identify the source of the infection and prevent further spread. Methods: Rectal swab and environmental samples were collected for bacterial and viral testing. A retrospective cohort study was conducted among 114 kindergarteners at the kindergarten. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated to assess associations of contact with the primary case, as well as food and water consumption. Results: Of the kindergarteners, 28 out of 114 (24.6%) met the case definition. The primary case occurred on 19 October, and subsequent cases began on 21 October. Sharing the same four-year-old class as the primary case (RR, 2.56; 95% CI, 1.35–4.87), being in the same regular class (RR, 2.37; 95% CI, 1.27–4.41), being on the same floor during after-school class (RR, 3.49; 95% CI, 1.74–7.00), and attending the same English class (RR, 1.98; 95% CI, 1.05–3.72) were statistically significant. Consumption of drinking water on the third floor and fourth floor on 20 October had significantly higher and lower RRs, respectively. Norovirus was detected in 9 out of 18 rectal swab samples (50.0%). Conclusions: This norovirus outbreak at the kindergarten was presumed to have been caused by person-to-person transmission from the primary case. Isolation and restriction of symptomatic children in kindergartens should be thoroughly implemented. Additionally, enhanced surveillance among family members of affected individuals is necessary to prevent further outbreaks. Full article

Vibrio parahaemolyticus is the leading bacterial cause of gastroenteritis associated with aquatic food consumption globally. This study aimed to determine the prevalence of V. parahaemolyticus in aquatic foods from Huzhou and to identify the serotypes, antimicrobial resistance, virulence factors, and genetic relatedness of the strains. A total of 306 isolates were detected from 1314 aquatic food samples from 2022 to 2024. The results indicated that the most prevalent serotypes were O1:KUT (17.0%), O2:K28 (13.7%), and O2:KUT (13.1%). Multilocus sequence typing analysis divided the 306 isolates into 175 sequence types (STs), and the predominant sequence type was ST864 (3.3%). Antimicrobial susceptibility tests showed that 2.6% of isolates were multidrug resistant. High resistance was observed to ampicillin (64.7%) and streptomycin (44.4%). A total of seven antimicrobial categories of resistance genes were identified, and the resistance gene bla_CARB was detected in all isolates. The virulence genes tdh and trh were found in 16 (5.2%) and 12 (3.9%) isolates, respectively. In addition, we observed that all the 306 V. parahaemolyticus isolates encode type III secretion systems 1. The phylogenomic analysis based on the whole-genome sequence revealed that the 306 isolates were divided into four clusters. Our findings broaden perspectives on V. parahaemolyticus genetic diversity and enhance our ability to assess the potential risks of its spread. Full article

Campylobacter jejuni is a leading cause of bacterial gastroenteritis worldwide which usually presents as mild, and self-limiting disease in immunocompetent individuals. However, in immunocompromised patients, such as those with common variable immunodeficiency, C. jejuni can cause severe recurrent infections requiring antibiotic treatment. Our study reports a case of a 37-year-old male patient with CVID, who had multiple episodes of C. jejuni intestinal infections over a 3.5-year period. A total of 27 stool samples were collected and analyzed between December 2020 and July 2024 during acute febrile diarrheal episodes, with C. jejuni isolated in 15 samples. Antimicrobial susceptibility testing (AST) during the course of the disease revealed three different antimicrobial resistance profiles including multi-drug-resistant phenotype. Whole genome sequencing was performed on three representative isolates, all identified as MLST type 367, ST-257 complex, with minimal genetic divergence, indicating a clonal origin. Genes and point mutations conferring resistance to macrolides, fluoroquinolones, beta-lactams, and tetracycline were identified in different C. jejuni isolates, along with key virulence factors linked to adherence, invasion, motility, and immune evasion. The genetic analysis of macrolide phenotypic resistance revealed different resistance mechanisms. Genotypic and phenotypic analyses of the same C. jejuni clone from single patient, and identified multidrug resistance pattern, present the first documented case of in vivo resistance development of C. jejuni in Croatia. This case highlights the role of prolonged antibiotic pressure in driving resistance evolution and underscores the need for careful antimicrobial stewardship and genomic monitoring in immunocompromised patients. Further research is needed to correlate phenotypic resistance with genetic determinants in Campylobacter spp. Full article