Search Results (527)

Salmonella enterica is a significant Gram-negative bacterium possessing over 2500 serovars capable of affecting both animals and humans and disseminating widely due to its adaptability, genetic diversity, and ability to form biofilms. Different serovars, such as S. enterica Typhimurium (ST), Enteritidis (SE), and Infantis (SI), display varying traits and survival strategies in harsh environments. Biofilms, composed of proteins, lipids, and DNA, enable bacteria to survive stresses such as pH changes, nutrient shortages, temperature fluctuations, and disinfectants. Evaluating disinfectants on inert surfaces is crucial for understanding their effectiveness and impact on poultry. This study assessed the efficacy of chlorine dioxide (ClO₂) disinfectant against ST, SE, and SI growth, biofilm formation, and biofilm removal at varying concentrations in vitro. Results showed serotype-dependent and condition-specific responses, with SE and SI being more affected than ST, which may be associated with differences in oxidative stress response mechanisms, highlighting the need for tailored disinfection protocols. Full article

The formation of biofilms by Salmonella is of considerable interest to the food production and medical industries. This study investigated the effects of a carrier medium (Luria–Bertani, Mueller–Hinton II, Brain Heart Infusion or chicken meat juice), temperature (14 °C, 23 °C or 37 °C) and surface type (adhesive, non-adhesive or suspension plate) on biofilm formation in 16 different Salmonella isolates belonging to the serovars S. Enteritidis (five isolates), S. Infantis (five isolates) and S. Typhimurium (six isolates). Chicken meat juice was found to have a moderate yet balanced supportive effect, while Mueller–Hinton II (MH-II) medium drastically supported biofilm formation at low temperatures, albeit with significant variation among the isolates. Temperature and medium also affected the antibacterial, biofilm inhibitory and destructive effects of essential oils. At 14 °C and 23 °C, 35% of essential oils exhibited antibacterial activity against Salmonella serovars at a concentration of 0.1%, as determined by the drop plate method. Ajowan, thyme, orange, clove and oregano EOs completely inhibited biofilm formation at a concentration of 0.1%. More than half of the 60 essential oils tested reduced the optical density of mature biofilms (OD: 0.15–0.36) to below 0.05; ajowan, lime, palmarosa, thyme, oregano and clove were the most effective, exhibiting antibacterial, biofilm inhibitory and biofilm destructive effects on all of the investigated Salmonella isolates. Full article

Lactic acid bacteria (LAB) are valuable natural bio-preservatives due to their ability to produce antimicrobial compounds such as organic acids, hydrogen peroxide, and bacteriocins. This study aimed to isolate and characterize LAB from Moroccan camel meat and evaluate their antimicrobial potential against major foodborne pathogens. From 2304 isolates obtained from fresh, fermented, and dried camel meat, 115 exhibited antimicrobial activity against Listeria monocytogenes, Salmonella enterica Enteritidis, and Staphylococcus aureus. Seven isolates demonstrated broad-spectrum activity with inhibition zones ranging from 15 to 30 mm. Physiological and biochemical tests, combined with API 20 Strep identification, revealed that most isolates belonged to Enterococcus faecium. These isolates are promising candidates for natural preservation of camel meat, offering a sustainable alternative to synthetic preservatives. These findings highlight the potential of camel-meat-associated lactic acid bacteria as natural, clean-label bio-preservatives, particularly in arid regions where camel meat serves as a vital protein source and limited cold-chain infrastructure increases the risk of spoilage. 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

Salmonella Enteritidis is a major threat to poultry health and food safety, underscoring the need for safe alternatives to conventional antibiotics. In this study, quercetin, a natural flavonoid with antibacterial and immunomodulatory properties, was evaluated using an integrated approach combining network pharmacology, molecular docking, in vitro antibacterial assays, and preliminary in vivo validation. Potential targets of quercetin and Salmonella Enteritidis were identified from the TCMSP and GeneCards databases, followed by protein–protein interaction analysis, topological screening, and GO/KEGG enrichment analyses. Five core targets, namely IL1B, IL6, STAT1, PTGS2, and IFNG, were identified and were mainly enriched in immune- and inflammation-related pathways. Molecular docking suggested favorable interactions between quercetin and these predicted targets. In vitro, quercetin showed moderate antibacterial activity against Salmonella Enteritidis, with a minimum inhibitory concentration of 256 μg/mL and a minimum bactericidal concentration of 512 μg/mL. In vivo, quercetin alleviated intestinal histopathological damage and reduced the transcriptional expression of the five target genes in infected chicks in a dose-dependent manner, with more evident effects at doses of 512 mg/kg or higher. These findings provide preliminary evidence that quercetin may exert both direct antibacterial and host-associated protective effects against Salmonella Enteritidis, although the underlying mechanisms require further validation. 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

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

Non-typhoidal Salmonella (NTS) is an important poultry-associated pathogen with major One Health and economic impacts, but data on its epidemiology and antimicrobial resistance in Nigeria remain limited. This study investigated the prevalence, serovar distribution, clonal relatedness, and antimicrobial resistance of NTS along the poultry production chain in Enugu State, southeastern Nigeria. A total of 2400 samples were collected, comprising feces (cecal content)/cloacal swabs from chickens (n = 1100), eggs (n = 400), chicken meat (n = 600), and stool samples from poultry workers (n = 300). Isolation and identification were performed using standard bacteriological methods, with confirmation by serotyping and polymerase chain reaction (PCR) targeting the invA gene. Genetic relatedness was assessed using enterobacterial repetitive intergenic consensus (ERIC)-PCR, and antimicrobial susceptibility was determined by the disk diffusion method. Overall, 47 (2.0%) Salmonella enterica isolates were recovered from 2400 samples, with the highest prevalence observed in eggs (3.5%), followed by human stool (3.3%), chicken meat (1.8%), and chicken feces (1.1%). Only 35 (11.8%) of the 297 sampled farms were positive for Salmonella, and recovery rates differed significantly (p = 0.0065) among sample sources. Five serotypes were identified, dominated by S. Typhimurium (57.4%), followed by S. Enteritidis (14.9%), S. Anatum (12.8%), S. Stanley (8.5%), and S. Agona (6.3%). ERIC-PCR revealed multiple clonal clusters, many containing isolates from mixed sources, indicating circulation of related strains between poultry and humans. All isolates were resistant to ampicillin, with high resistance to tetracycline (76.6%), sulphamethoxazole–trimethoprim (51.1%), and fluoroquinolones. Overall, 80.9% of isolates were multidrug-resistant, with a mean Multiple Antibiotic Resistance Index of 0.29, highest among isolates from chicken feces. Although the prevalence of NTS was low, the presence of genetically related multidrug-resistant strains across the production chain underscores the role of poultry as a reservoir for zoonotic transmission and highlights the need for coordinated One Health surveillance and antimicrobial stewardship strategies in Nigeria. Full article

Background/Objectives: Multidrug-resistant Salmonella enterica serovar Enteritidis, especially those isolated from humans, remains a public concern. In the present study, S. Enteritidis strain 31404 was obtained clinically from a fecal sample of a fifteen-year-old girl, who was positive for bla_NDM-13. Methods: Antibiotic susceptibility testing and whole genome sequencing were performed. Core genome MLST and hierarchical clustering (HierCC) were performed using EnteroBase. Population structure analysis of 57 S. Enteritidis isolates collected between 2023 and 2025 in Jiaxing city was conducted. A comparative structure analysis of bla_NDM-13-positive plasmids was also performed. Results: S. Enteritidis strain 31404 was resistant to 13 antimicrobial agents. We found that strain 31404 belonged to ST11 and carried resistance genes, such as bla_NDM-13, bla_CTX-M-14, ble_MBL, fosA3, qnrS, and tet (A). bla_NDM-13 was located on an IncI1-I (α) plasmid designated as p31404-NDM13. S. Enteritidis isolate 31404 was closely related to PNUSAS514422, which was isolated from the United States in 2025. Comparative genetic environment related to bla_NDM-13-positive plasmids available in the NCBI database indicates that ΔTn125-mediated contexts were commonly associated with bla_NDM-13. IS1294 (IS91 family), which replaces ISAba125, is likely to mobilize bla_NDM-13. Conclusions: The findings in this study provide insights into the molecular characterization and diversification of bla_NDM-13. The identification of bla_NDM-13-containing transferable plasmids in different serotypes of Salmonella isolates (such as S. Rissen, S. Typhimurium, and S. Enteritidis) in different cities in China highlights the risk of the spread of carbapenem-resistant genes among Salmonella isolates. Full article

Salmonella enteritidis (SE) is recognized as a primary etiological agent of foodborne infection and food poisoning. Selective and sensitive determination of SE in animal-derived products is of great importance for ensuring safety in the food industry. Here, we report a highly sensitive and specific competition assay for detecting SE in eggs without interference from background fluorescence, by using persistent luminescent nanoparticles (PLNPs) as luminescent probes in combination with aptamer recognition and magnetic separation. Initially, the SE-specific aptamer (SEapt), as previously reported, was conjugated onto the surface of Fe₃O₄ magnetic nanoparticles to serve as both the recognition and separation unit. Meanwhile, the ZnGa₂O₄:Cr (PLNPs) were functionalized with the aptamer-complementary DNA (cDNA), serving as the PL signal generator. The constructed PL aptasensor is composed of the aptamer-conjugated MNPs (MNPs-SEapt) and cDNA-functionalized PLNPs (PLNPs-cDNA), integrating the merits of the long-lasting luminescence of PLNPs, the magnetic separation ability of MNPs and the selectivity of the aptamer. This integration offers a promising approach for autofluorescence-free determination of SE in food samples. The proposed aptasensor exhibited excellent linearity in the range from 1.0 × 10²–1.0 × 10⁷ CFU mL⁻¹ with a limit of detection as low as 32 CFU mL⁻¹. The precision for 11 replicate determinations of 1.0 × 10³ CFU mL⁻¹ SE was 3.4% (relative standard deviation). The developed aptasensor achieved recoveries ranging from 98.8% to 102.8% for the determination of SE in the presence of common foodborne bacterial interferents. The method was successfully applied to the analysis of Salmonella genus in egg samples. In principle, the proposed platform may be adapted to other food matrices by substituting the target-specific aptamer, pending target-dependent optimization and validation. Full article

Salmonella is a major cause of foodborne illness worldwide, posing significant risks to public health and food safety. This study investigated the prevalence, serovar distribution, genotypic characteristics, and antimicrobial resistance (AMR) profiles of Salmonella. A total of 2515 food samples were collected from retail markets, supermarkets, and food processing facilities, and 13,670 stool samples were obtained from sentinel hospitals across 14 cities in Liaoning. The Kruskal–Wallis test was used to compare genetic features among serovars, followed by Dunn’s post hoc test for pairwise comparisons. A total of 314 Salmonella strains were identified, with raw poultry showing the highest detection rate (28.88%) among food sources and children aged 0–6 years (3.47%) the highest among the clinical age groups. Among food samples, S. Enteritidis was the most prevalent serovar (42.6%), and it was also the most common in clinical samples (35.8%); in contrast, S. 4,[5],12:i:- was dominant in pediatric clinical cases. According to AMR analysis, 90.13% of strains were resistant to at least one antibiotic and 67.83% were multidrug-resistant (MDR), with the highest resistance to ampicillin (68.47%). Analysis revealed that S. 4,[5],12:i:- harbored the ASSuT resistance module (blaTEM-1B, aph(3″)-Ib/aph(6)-Id, sul2, tet(B)). Extensive MDR phenotypes were observed in S. Indiana and S. Kentucky, associated with abundant insertion sequences (IS) and resistance genes (ARGs), including clinically critical determinants (blaNDM-9, mcr-1.1, rmtB). The highest mean virulence factor (VF) count (111.17) was observed in S. Enteritidis, contributing to its epidemiological success. Conversely, S. Indiana and S. Kentucky, predominantly food-associated serovars, exhibited reduced virulence but served as critical AMR reservoirs. These findings highlight the epidemiological characteristics and AMR risks of Salmonella in food and clinical settings, providing critical data for food safety and clinical antimicrobial stewardship. Full article

Environmental pollution affects the health of living organisms, provoking the emergence of new diseases and infections. In search of sustainable and effective solutions, this study presents a “green” synthesis of five silver nanocomposites with activated carbon (Ag-NACs) obtained from waste biomass from peach shells. The process is carried out in an aqueous environment and does not use toxic organic solvents. The chemical composition, structural properties and morphology of the synthesized Ag-NACs were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR). Comparative analysis under different conditions, including silver concentration (0.5%, 1.5%, 4.0% and 8.0%) and impregnation time (24 and 72 h), identified the samples with 4.0% and 8.0% Ag as optimally structured, showing the strongest antibacterial activity. The results confirmed the synergistic effect and mechanism of the carbon composites, which effectively attract bacterial cells while the silver ions inhibit the growth of various pathogens. This efficacy was demonstrated against both Gram-positive (Gram⁺), Bacillus subtilis, Bacillus spizizenii, Staphylococcus aureus, Listeria innocua, and Enterococcus faecium, and Gram-negative (Gram⁻) bacterial strains, Escherichia coli, Salmonella typhimurium, Salmonella enteritidis, and Stenotrophomonas maltophilia, which highlights the significant potential of Ag-NACs. Full article

In this study, Chinese medicinal herbs were evaluated as potential antibiotic substitutes for Chinese soft-shelled turtle (Pelodiscus sinensis). Forty-five herbs were initially screened for antibacterial activity against Salmonella enteritidis, Escherichia coli, and Shigella flexneri. Nine herbs exhibiting broad-spectrum inhibitory effects were selected and subjected to microbial fermentation, after which their antibacterial activities were reassessed and applied as dietary supplements in feeding trials. The results showed that fermentation altered the antibacterial activities of several herbs and enhanced their overall functional performance. Dietary supplementation with fermented Chinese herbal medicine did not adversely affect feed utilization but significantly improved hematological parameters, liver and kidney function indicators, antioxidant capacity, and nonspecific immune responses. Furthermore, turtles fed fermented herbal diets exhibited higher survival rates following bacterial challenge. Intestinal microbiota analysis based on 16S rRNA gene sequencing indicated that fermented herbal supplementation modulated microbial community structure by reducing potential pathogens and increasing beneficial bacterial taxa associated with intestinal health. These findings suggest that microbial fermentation effectively enhances the biological efficacy of Chinese medicinal herbs. Fermented herbal feed additives represent a promising green alternative to antibiotics for soft-shelled turtle aquaculture. The global ban on prophylactic antibiotics drives the need for safe, effective feed alternatives. Microbial fermentation of Chinese herbs (FCM) is proposed to enhance efficacy and detoxification, but its comprehensive effects in aquaculture require deeper investigation. This study evaluated compound unfermented (CM) and fermented (FCM) Chinese herbal supplements on the Chinese soft-shelled turtle (Pelodiscus sinensis). Initial screening showed fermentation generally enhanced the antibacterial activity of the herbs against common enteric pathogens (S. enteritidis, E. coli, S. flexneri). Results indicated that the FCM diet significantly improved physiological status, leading to higher red blood cell counts, better liver/kidney function (reduced ALT/AST, UREA), and stronger immune/antioxidant responses (increased Lysozyme and T-AOC) compared to CM or control diets. Critically, the FCM group achieved the highest survival rates across all single and combined pathogen challenges, demonstrating superior protective efficacy. Furthermore, FCM effectively modulated the gut microbiota, enriching beneficial fermentative bacteria. In conclusion, microbial fermentation significantly amplifies the health-promoting and protective benefits of Chinese herbal supplements in soft-shelled turtles, positioning FCM as a promising green alternative for disease control in aquaculture. Full article

Foodborne diseases remain a major public health challenge. Among them, salmonellosis is one of the most frequently reported illnesses, associated with clusters and outbreaks and with considerable morbidity, potentially severe in vulnerable populations. Children are more susceptible due to biological, behavioral, and dietary factors. This study aimed to summarize and describe national surveillance data from the Mandatory Notification System, combined with serotyping data, on reported salmonellosis cases in Greece during the period 2005–2024, with a focus on children aged 0–14 years. During the study period, a total of 7340 salmonellosis cases were reported among children aged 0–14 years. Notification rates declined gradually until 2021, followed by an increase through 2024. The mean annual notification rate was 23.0 cases per 100,000 population, with the highest incidence observed among children aged 0–4 years. A clear seasonal pattern was observed, with a peak during summer months, alongside notable geographical variation. The most frequently identified serovars were Salmonella Enteritidis and Salmonella Typhimurium. These findings indicate that salmonellosis remains a public health concern in the pediatric population, highlighting the need for enhanced surveillance, improved food hygiene practices, and targeted prevention strategies to reduce disease burden. Full article