Search Results (318)

Background: Salmonella enterica, a major foodborne pathogen, poses a severe global public health threat. However, data regarding its carriage characteristics, transmission patterns, and association with intestinal microbiota in healthy populations of Xinjiang, China, remain insufficient, limiting the formulation of targeted salmonellosis prevention and control strategies. Methods: In this study, 31 Salmonella enterica strains isolated from more than 2000 healthy individuals in Urumqi were subjected to whole-genome sequencing to analyze serovars, antimicrobial resistance (AMR) genes, and virulence genes. Meanwhile, metagenomic sequencing was performed on 50 fecal samples (culture negative) from 2000 healthy individuals to investigate intestinal microbiota structure, Salmonella enterica prevalence, and related microbial taxa. Results: The results showed that 60% of samples (30/50) were positive by the read-based criterion (≥1000 Salmonella-specific reads), while the assembly-verified criterion (≥1000 reads and contigs > 1 kb) confirmed Salmonella-specific sequences in 12% (6/50). Among the 31 culture-confirmed isolates, Salmonella Typhimurium and Salmonella Paratyphi B were the dominant serovars, together accounting for 60%. All isolates harbored core virulence genes for Type III secretion system and adhesion factors, with low AMR gene carriage and no multidrug-resistant strains. Phylogenetic analysis showed that Urumqi-derived isolates were distributed across multiple genomic clusters, suggesting active inter-regional circulation of S. enterica within the available dataset. Salmonella enterica carriage did not affect gut microbial α-diversity but altered community composition, with Escherichia coli, Shigella flexneri, and Klebsiella pneumoniae as key associated taxa. Conclusions: This study found that Urumqi-derived isolates are widely distributed across genomic clusters in Xinjiang, with a unique local transmission chain identified, though definitive source attribution requires further geographically balanced sampling. Salmonella enterica carriage exhibited ecological niche synergy with intestinal Enterobacteriaceae, but did not significantly affect gut microbial diversity. Full article

Background: Salmonellosis is a major global public health concern, commonly caused by serovars such as Salmonella enterica serovar Typhimurium and Salmonella enterica serovar Enteritidis. Rare serovars, however, may represent underrecognized links between environmental reservoirs and human infection. Salmonella enterica serovar Haifa is a sporadic serotype primarily associated with livestock and environmental sources and has previously been reported in Indian poultry but not in human clinical cases to date. Case Presentation: A 70-year-old male with a history of type 2 diabetes, presented with acute watery diarrhea and dehydration. One week prior to symptom onset, the patient reported direct contact with cattle and poultry in a rural setting. Laboratory investigations revealed leucopenia and elevated procalcitonin (3.73 ng/mL). Stool culture yielded non-lactose fermenting colonies on MacConkey agar and H₂S-producing colonies on Hektoen enteric agar. The isolate was identified via VITEK 2 and confirmed as Salmonella enterica serovar Haifa by the National Institute for Research in Bacterial Infections (NIRBI). Antimicrobial susceptibility testing (AST) revealed that the isolate showed resistance to ampicillin, ceftriaxone, and ciprofloxacin. The patient was successfully treated with a three-day course of intravenous Azithromycin (1 g) and achieved rapid clinical recovery. Conclusions: To the best of our knowledge, this case represents the first reported human infection caused by S. Haifa in India. The finding highlights the potential zoonotic risk of rare non-typhoidal Salmonella serovars and emphasizes the importance of surveillance, routine serotyping, and antimicrobial resistance monitoring within a One Health framework. Full article

Salmonellosis is a significant zoonotic and foodborne disease caused by Salmonella. As a primary reservoir, poultry infections can result in decreased survival rates, diminished production performance and contamination of poultry products, thereby posing a serious threat to the sustainable development of poultry farming and human health. In this study, a total of 979 samples were collected from a laying hen production chain, and 84 Salmonella strains were isolated, with an isolation rate of 8.58% (84/979). Among these, 54 isolates (11.2%) were from commercial house samples, followed by nine isolates (10.8%) from market samples, 10 isolates (5.88%) from hatchery samples, and 11 isolates (4.55%) from breeder house samples. Six different serotypes were identified, with Salmonella enterica serovar Enteritidis (S. Enteritidis) being the predominant serotype (41.7%), followed by Salmonella enterica serovar Typhimurium (S. Typhimurium) (22.6%) and Salmonella enterica serovar Infantis (S. Infantis) (21.4%). The S. Enteritidis was distributed in various production stages in the laying hen production chain. Among the 16 antibiotics tested, 30 selected strains exhibited 100% resistance to nalidixic acid (NAL) and ciprofloxacin (CIP), attributed to mutations in the quinolone resistance-determining region (QRDR) of the gyrA gene. Following this, the resistance rates for ampicillin (AMP), amoxicillin–clavulanate (AMC), and streptomycin (STR) were 56.7%. Antimicrobial resistance genotypes were consistent with the drug resistance phenotype. Whole genome sequencing (WGS) phylogenetic analysis based on core genome single nucleotide polymorphism (cgSNP) revealed that Salmonella can spread across various stages of the laying hen production chain, posing a potential threat to human health. Furthermore, 165 virulence-associated genes were identified among the investigated isolates, indicating a highly conserved virulence repertoire. This study investigates the prevalence of Salmonella within a laying hen production chain, providing a scientific foundation for the effective prevention and control of Salmonella infection. Full article

Multidrug-resistant (MDR) Salmonella Typhimurium, largely spread through poultry products, increasingly resists antibiotic treatment. We evaluated dietary pomegranate peel extract-loaded nano-emulsions (PomNEs) on performance, immunity, antioxidant capacity, and S. Typhimurium resistance in laying hens. A total of 250 15-week-old Hy-Line Brown hens received a basal diet or diets supplemented with PomNEs at 0.3, 0.6, or 1.2 g/kg, and then were challenged with S. Typhimurium at 34 weeks. Hens fed PomNEs, especially PomNEs1.2, showed improved egg production and feed efficiency before challenge and restored normal output afterward. Supplementation reduced Salmonella colonization in the ovaries, liver, and eggs, with considerable reduction in eggs and ovaries at the highest dose by ten weeks, and down-regulated bacterial virulence genes (hilA, invA). Immune function improved through higher phagocytic activity, intracellular killing, and lysozyme levels, lower nitric oxide, up-regulated IgA and β-defensins (AvBD6, AvBD12), and suppressed pro-inflammatory cytokines and chemokines. Intestinal and ovarian redox balance improved via reduced COX2 and elevated GPX-1, HO-1, NQO1, SOD-1, and CAT expression. These benefits support PomNEs as promising natural feed additives to enhance laying performance, antioxidant defense, and immunity against salmonellosis, offering a sustainable strategy for supporting disease control in poultry production. Full article

Historical microbiological collections linked to epidemiological and clinical metadata represent a valuable resource for retrospective investigation of long-term changes in pathogen populations. In this retrospective study, we analyzed the epidemiological, clinical, and microbiological information recorded in the datasheets accompanying Salmonella enterica isolates archived in a historical collection assembled in Lombardy, Italy, between 2001 and 2016. Overall, metadata associated with 6624 salmonellosis cases with confirmed serovar identification were included to describe serovar distribution, bloodstream infections, and antimicrobial resistance (AMR) patterns within the collection. Four serovars (S. Typhimurium, S. Enteritidis, S. 1,4,[5],12:i:-, S. Napoli) accounted for approximately 80% of all cases. The relative representation of S. Napoli increased over the study period, whereas S. Choleraesuis showed the highest proportion of bloodstream isolates and predominantly affected adults. Overall, resistance to penicillins (46.9%) and tetracyclines (48.0%) was common, whereas resistance to fluoroquinolones (2.9%) and third-generation cephalosporins (<2%) remained low. Among invasive non-typhoidal Salmonella (iNTS) infections, 69.3% of isolates were resistant to at least one antimicrobial class, and 34.7% exhibited multidrug resistance (MDR), with fluoroquinolone resistance increasing to 13.9%. These findings highlight the value of historical microbiological collections and their associated metadata for documenting long-term changes in serovar distribution, invasive infections, and AMR, while emphasizing their importance as a resource for future molecular epidemiology and One Health surveillance. Full article

Salmonella is a globally significant foodborne intracellular pathogen, and invasive salmonellosis poses a major global public health threat. The NLR family CARD-containing protein 4 (NLRC4) inflammasome, a pivotal cytosolic innate immune sensor, specifically recognizes Salmonella flagellin and type III secretion system (T3SS) components via the NAIP (NLR family apoptosis inhibitory protein) family. Upon activation, it triggers pyroptosis, pro-inflammatory cytokine release, and infected intestinal epithelial cell extrusion, serving as a central pathway for host defense against Salmonella colonization and systemic spread. This work systematically summarizes the structural composition, activation mechanisms, post-translational modifications, and regulatory protein network of the NLRC4 inflammasome, and highlights the molecular mechanisms by which Salmonella evades NLRC4 surveillance through multiple strategies: transcriptional downregulation of immunogenic ligands, structural modification of T3SS components, secretion of effector proteins, and chemotaxis-virulence synergy. A comprehensive delineation of the co-evolutionary arms race between Salmonella and the NLRC4 inflammasome provides an integrated mechanistic framework for understanding host–pathogen immune interplay. Deciphering the mechanisms of bacterial immune evasion on this basis holds critical importance for identifying novel anti-infective targets and advancing translational preventive and therapeutic strategies against salmonellosis. Full article

This scoping review evaluates the role of vector-associated dissemination in contaminating the Philippine food supply chain with antimicrobial-resistant (AMR) Salmonella, an emerging infectious disease threat, using a One Health perspective to map the mechanisms through which insects and rodents bridge environmental reservoirs to human food systems. This scoping review was conducted and reported in accordance with the PRISMA-ScR guidelines. From 1969 records identified through systematic database searches, 52 studies met the inclusion criteria. These comprised 21 primary Philippine studies, 28 non-Philippine studies (including ASEAN-based historical baseline reports), and 3 policy/gray literature studies, prioritized to reflect tropical ecological and agricultural settings. Results suggest that intensive swine and poultry farming may contribute to the emergence of multidrug resistance (MDR) linked to genes such as bla_TEM and qnr. Evidence suggests that Salmonella persists in environmental matrices, such as manure and irrigation water, and that synanthropic vectors, including Rattus rattus and various fly species, potentially serve as biological and mechanical bridges in transmission. Clinical data reveal an alarming trend toward invasive non-typhoidal salmonellosis (iNTS) showing reduced susceptibility to cephalosporins and fluoroquinolones. Despite these findings, major evidence gaps remain, particularly regarding the prevalence of vector-borne Salmonella in pre-harvest produce. Consequently, mitigation requires a One Health framework that integrates non-antibiotic interventions, pest management to disrupt transmission pathways, and rapid diagnostic tools, such as loop-mediated isothermal amplification (LAMP), to enhance market surveillance. Full article

Recent foodborne outbreaks by Salmonella Typhimurium associated with the consumption of ‘Maradol’ papaya have prompted an assessment of the pathogen’s behavior with regard to the fruit. The objective of this research was to assess the survival and possible internalization of S. Typhimurium in inoculated ‘Maradol’ papaya harvested at two maturity stages and stored for various days at 11 °C and 24 °C. The physicochemical analysis on fruit included firmness (N), total soluble solids (%), and pH. The location of S. Typhimurium in fruit exocarp and mesocarp tissues was observed using confocal laser scanning microscopy (CLSM). Results indicated that the high temperature (24 °C) was the most important factor for the survival of S. Typhimurium. At this same temperature, it was the variable firmness that was the most affected, regardless of storage days, whether inoculated or not. The principal component analysis (PCA) separated the data into two components that explained 57% of the variance. PC1 linked higher S. Typhimurium populations with declining firmness, TSS, and exocarp pH were found in fruit stored at 24 °C, whereas PC2 was associated with moderate physicochemical changes at 11 °C. The CLSM observations confirmed superficial colonization of the bacteria on papaya fruit rather than an internalization but only at 24 °C, regardless of ripening stage throughout the 7 days sampling period. Maintaining the cold chain is essential to mitigate the risk of salmonellosis in papaya. Full article

Background: Salmonella Typhimurium is a major pathogen causing non-typhoidal salmonellosis in humans. Poultry is a major reservoir of S. Typhimurium. Currently available vaccines against S. Typhimurium are not very effective. Therefore, the search for novel adjuvants to improve vaccine efficacy is a priority for developing effective and efficient vaccines. Method: In this study, next-generation adjuvants, such as calcium phosphate nanoparticles, are being evaluated. Our objective was to assess the potential of calcium phosphate nanoparticles, using outer membrane proteins of Salmonella Typhimurium as antigens, for immune-potential testing in poultry, with Montanide as a control. The toxicity of the prepared vaccine formulation was evaluated in rats. Results: CaP-Omp-Nps in the 30–45 nm size range showed a protein entrapment efficiency of 42.5% and a loading capacity of 50.3%. Both vaccinated groups, calcium phosphate outer membrane protein nanoparticles (CaP-Omp-Nps) and Montanide, induced an efficient humoral immune response, with mean titers of 3.48 + 0.0245 and 4.9 + 0.0142 on the 15th day, 3.5 + 0.0118 and 4.79 + 0.009 on the 30th day, and 4.48 + 0.427 and 5.31 + 0.154 on the 45th day post vaccination, respectively, indicating an improvement (CaP-Omp-Nps group) or stability (Montanide group) over the study period. Further, the CaP-Omp-Nps group revealed a better cell-mediated immune response than the Montanide-Omp group. The toxicity study in rats showed no significant differences in serum biomarkers and blood chemistry parameters, indicating that the nano-vaccine formulation is non-toxic and safe. Outer membrane proteins of Salmonella Typhimurium, when used with a few conventional adjuvants, could not produce a balanced Th1 and Th2 immune response against Salmonella Typhimurium. Conclusions: In this study, we developed a novel nano-vaccine formulation composed of outer membrane proteins of Salmonella Typhimurium and calcium phosphate nanoparticles. The vaccine formulation was found to be safe and could elicit the desired Th1 and Th2 immune responses, as evidenced by humoral, cell-mediated, and protective immunity produced by the nano vaccine in poultry. Therefore, the present findings suggest that the CaP-Omp-Nps vaccine may be an efficient, safe, and cost-effective vaccine against Salmonella Typhimurium. Full article

Salmonellosis is a global foodborne pathogen with zoonotic importance that seriously threatens livestock breeding and human health. Due to the implementation of an anti-resistance policy, probiotics as an alternative to antibiotics have attracted widespread attention. In this study, the widely used probiotic Escherichia coli Nissle 1917 (EcN) was selected to study its protective effect on mice infected with Salmonella typhimurium. Two mice groups (n = 15) were treated with either EcN and PBS. Flow cytometry showed that the frequency of mature dendritic cells in the Peyer’s patch was significantly increased compared to the PBS group. Previous administration of EcN protected against challenge with Salmonella typhimurium infection as an increased survival rate of the mice, a decreased degree of pathological changes, and the number of live bacteria in the spleen and liver were recorded compared to the control group. The results of 16S rRNA high-throughput sequencing of fecal microbial flora showed that EcN could reduce the abundance of microorganisms in the intestine and reduce the proportion of Lactobacillus, while Ruminococcaceae sp., Rikenella sp. and Bifidobacterium sp. disappeared. In contrast, the abundance of Bacteroides increased, which reduced the effect of Salmonella typhimurium on the distribution of intestinal microorganisms. Our results demonstrated that EcN has a protective effect against Salmonella typhimurium infection and may act as a candidate probiotic bacterium to apply in the future. 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

Salmonella spp. is a major zoonotic pathogen. Although reptiles are mostly considered subclinical carriers, clinical disease may develop following immunosuppression. Clinical salmonellosis in reptiles has been extensively reported; however, the condition has been rarely described in bearded dragons (Pogona vitticeps). We retrospectively analyzed six cases of salmonellosis in bearded dragons and characterized the pathological, immunohistochemical, and bacteriological findings. Clinical signs and gross findings were mostly non-specific. Histological findings mainly consisted of fibrinonecrotizing enterocolitis (83.3%); necrotizing or granulomatous hepatitis (66.7%); pneumonia including bronchopneumonia or interstitial pneumonia in one case each (33.3%); tubulointerstitial nephritis with tubular necrosis (16.7%); and coelomitis (16.7%). Salmonella enterica subsp. houtenae was cultured in three cases (33.3%), whereas S. enterica subsp. enterica serovar Rissen, S. enterica subsp. enterica serovar Cotham, and S. enterica subsp. diarizonae were cultured in one case each. Intralesional bacteria were detected via immunohistochemistry in kidneys and colon in two cases (33.3%). The predominance of lesions in the intestines and liver likely reflects initial intestinal colonization followed by hematogenous dissemination to the liver. Hepatic lesions are thought to represent different stages along a continuum, progressing from acute necrosis to discrete granuloma formation. Renal and respiratory involvement was infrequent, as reported in other reptile species. Some of the isolated Salmonella subspecies (S. diarizonae and S. houtenae) are well-recognized causes of clinical disease in other reptile species but not previously identified in bearded dragons. This study provides a comprehensive pathological, immunohistochemical, and bacteriological characterization of salmonellosis in bearded dragons, thus raising awareness and assisting in the identification of this condition. Full article

Salmonella Enteritidis (SE) infections in poultry threaten animal health and food safety. Antibiotic resistance makes alternative treatments necessary. Bamboo polyphenols (BP), recovered from bamboo vinegar—a byproduct of bamboo carbonization—represent a sustainable and eco-friendly candidate for combating avian salmonellosis. We tested BP against SE using laboratory tests and a chick model. BP showed a minimum inhibitory concentration of 1:256 against SE. We infected chicks with 1.8 × 10⁸ CFU per bird. The results indicated that adding 0.2% (v/v) BP to drinking water demonstrated optimal efficacy for prevention. Adding 0.4% (v/v) BP demonstrated optimal efficacy for treatment. Prophylactic BP administration effectively prevented SE-induced mortality and tissue damage. As a therapeutic agent, BP performed comparably to berberine. BP lowered the bacterial load in organs and increased chick survival to 96%. At the transcriptional level, BP administration downregulated the TLR4/MyD88/NF-κB pathway. It also improved antioxidant levels, strengthened the intestinal barrier, and restored healthy gut bacteria. These results indicate that BP could serve as a potential and sustainable feed additive to reduce SE infection in poultry. Full article

The effective control of foodborne salmonellosis relies on the rapid and reliable detection and identification of the pathogen. Reliable detection tools for identifying the most common Salmonella serovars should translate to a considerable alleviation of the health burden attributed to Salmonella. We have developed a PCR assay for the rapid identification of colonies of Salmonella enterica serovar Thompson, a common serovar. Genomic analyses of publicly available sequences of Salmonella Thompson revealed the presence of a unique, Thompson-specific fragment, which we have used to design a pair of oligonucleotides, STho-F and STho-R, for the PCR amplification of an 808 bp DNA fragment. Using crude DNA extracts, the 808 bp fragment was detected in 77 out of 78 isolates of S. Thompson (sensitivity = 98.7% n = 78 isolates) but not in any of the non-Salmonella organisms tested (n = 100; 100% specificity) nor in non-Thompson Salmonella serovars (n = 100; 100% specificity). The sensitivity (inclusivity) and specificity (exclusivity) indices of the PCR assay for S. Thompson met the standard regulatory requirements. The Thompson primer pair was compatible with other primers pairs in a multiplex PCR designed for three other common Salmonella serovars. Colonies belonging to the Enteritidis serovar (n = 100), Heidelberg serovar (n = 100), Typhimurium serovar (n = 100), and Thompson serovar (n = 77) were correctly designated, indicating excellent inclusivity and exclusivity scores for all four Salmonella serovars tested in a single multiplex PCR. Full article

Multidrug-resistant (MDR) Salmonella enteritidis infections cause high mortality and devastating economic losses in poultry, pose severe threats to animal health and food safety, and create an urgent demand for effective antibiotic alternatives. Herein, we developed a cationic liposome-encapsulated bacteriophage endolysin Lys40 (designated Lys40-Lip), and systematically evaluated its therapeutic efficacy in a chick model challenged with Salmonella enteritidis strain S4. Recombinant Lys40 was encapsulated into cationic liposomes with an encapsulation efficiency (EE) of 34.83%. The resulting Lys40-Lip nanoparticles had a hydrodynamic diameter of 137.3 ± 4.1 nm, a high positive zeta potential of +42.5 ± 0.3 mV, and excellent stability, retaining 78.52% of its initial bactericidal activity after 56 days of storage at 4 °C. Following a three-day oral treatment in Salmonella enteritidis S4-infected chicks, Lys40-Lip significantly increased survival rates in a dose-dependent manner (72.22% to 88.89% for low-to-high dose vs. 44.44% in infected controls, p < 0.05) and reduced ileal Salmonella enteritidis S4 colonization by 28.8% compared to free Lys40. Histopathology revealed Lys40-Lip restored duodenal villus integrity and reduced jejunal and ileal inflammation. Serum cytokine analysis confirmed that Lys40-Lip effectively regulated the host inflammatory response, significantly downregulating the pro-inflammatory cytokines IL-1β and IL-6, and upregulating the anti-inflammatory cytokine IL-10. Crucially, liposomal encapsulation overcame the outer membrane barrier of Gram-negative bacteria via charge-driven fusion mediated by its high positive surface potential (+42.5 ± 0.3 mV), enabling targeted delivery of Lys40 without the need for EDTA or other outer membrane permeabilizers. Lys40-Lip significantly improved the therapeutic outcomes of avian salmonellosis via synergistic direct bactericidal activity, intestinal barrier protection and inflammatory response regulation, offering a promising nanotherapeutic strategy for the control of this disease in veterinary practice. Full article