In vitro antibacterial activity and physicochemical properties of a crude methanol extract of the larvae of the blow fly Lucilia cuprina

The emergence of multidrug‐resistant bacterial strains has prompted the reintroduction of maggot therapy in the treatment of chronic, infected wounds. Many previous studies have demonstrated the potent antibacterial activity of larval excretions/secretions of the blowfly Lucilia sericata (Meigen) (Diptera:Calliphoridae) against bacteria. However, the antibacterial activity of its sibling species, Lucilia cuprina (Wiedemann) (Diptera:Calliphoridae) against a wide range of pathogenic bacteria has never been determined. The aim of this study was to develop a new procedure to produce whole body extract of larvae of L. cuprina via methanol extraction as well as to demonstrate the in vitro antibacterial activity of this extract against seven selected wound pathogens (Staphylococcus aureus, methicillin‐resistant S. aureus, S. epidermidis, Streptococcus pyogenes, Klebsiella pneumoniae, Pseudomonas aeruginosa and Escherichia coli). The turbidimetric assay demonstrated that L. cuprina larval extract was significantly potent against all bacteria tested (P < 0.001). Additionally, colony‐forming unit (CFU), agar well diffusion and minimum inhibitory concentration assays have confirmed the apparent potency of larval extract against P. aeruginosa. The reconstituted larval extract was highly robust and thermally stable. These observations substantiated the feasibility of the methanol extraction method in the production of larval extract.     

Antibacterial and antilarval activity of deep-sea bacteria from sediments of the West Pacific Ocean

Abstract

Deep-sea microorganisms are a new source of bioactive compounds. In this study, crude ethyl acetate extracts of 176 strains of deep-sea bacteria, isolated from sediments of the West Pacific Ocean, were screened for their antibacterial activity against four test bacterial strains isolated from marine biofilms. Of these, 28 deep-sea bacterial strains exhibited antibacterial activity against one or more of the bacteria tested. Active deep-sea bacterial strains belonged mainly to the genera of Pseudomonas, Psychrobacter and Halomonas. Additionally, antilarval activity of 56 deep-sea bacterial strains was screened using Balanus amphitrite larvae. Seven bacterial strains produced metabolites that had strong inhibitive effects on larval settlement. None of these metabolites showed significant toxicity. The crude extract of one deep-sea Streptomyces strain could completely inhibit larval settlement at a concentration of 25 μg ml^?1.     

Detection of antimicrobial substances from larvae of the black soldier fly,Hermetia illucens (Diptera: Stratiomyidae)

Maggots have become highly successful in the treatment of non‐healing wounds and multidrug‐resistant pathogen infections. The main objective of this study was to extract antibacterial substances from larvae of the black soldier fly, Hermetia illucens. To induce immune responses, we septically injured the larvae with a contaminated needle. Lyophilized H. illucens larvae were homogenized and extracted with acidic methanol. We examined the antifungal and antibacterial effects of the low molecular weight antimicrobial factors within the larval extract on the growth of a broad range of microorganisms, including Gram‐positive Staphylococcus aureus, methicillin resistant Staphylococcus aureus (MRSA), and Gram‐negative Pseudomonas aeruginosa. Furthermore, we isolated the anti‐MRSA substances from the larval extract using high performance liquid chromatography. These investigations revealed that the larval extract possessed a broad‐spectrum of antibacterial activity, demonstrating that secretions of H. illucens larvae prove useful in the fight against MRSA and can potentially be a source of novel antibiotic‐like compounds for infection control.     

Intranasally administered Lactobacillus gasseri TMC0356 protects mice from H1N1 influenza virus infection by stimulating respiratory immune responses

We conducted a study to evaluate the possibility that intranasal administration of a new probiotic strain Lactobacillus gasseri TMC0356 (TMC0356) may protect host animals from influenza virus (IFV) infection, which was indicated by enhanced respiratory immune responses in a mouse model. After 3 days of exposure to TMC0356, BALB/c mice were intranasally infected with IFVA/PR/8/34 (H1N1). Lung cells were isolated from the tested mice and evaluated for cytotoxicity against YAC-1 cells. After intranasal treatment with TMC0356, mice showed a lower morbidity and higher survival rate compared to control mice (P < 0.05). The cytotoxicity of lung cells isolated from mice after intranasal treatment against YAC-1 cells was statistically higher than that of lung cells isolated from control mice (P < 0.05). Intranasal administration of TMC0356 significantly increased mRNA expression of interleukin (IL)-1β, tumor necrosis factor, IL-10, and monocyte chemotactic protein-1 (P < 0.01). These results suggest that intranasal administration of TMC0356 may protect the host animal from IFV infection. They also indicate that TMC0356 can enhance respiratory cell-mediated immune responses of host animals characteristically with up-regulated activation of lung natural killer cells. Further studies will evaluate the possible role of the immune stimulatory effects of TMC0356 within the protective effects of this bacterium against IFV, as observed in the present study.     

Augmentation of various immune reactivities of tumor-bearing hosts with an extract ofCordyceps sinensis

In order to enhance general reactivity of immune system in the tumor-bearing host, we employed extract ofCordyceps sinensis (CSE) as a biological response modifier.Cordyceps sinensis is an interesting material produced by a kind of mushroom parasitic to larval moths and was used to hasten recovery from exhaustion in ancient China.In this experiment, C57BL/6 mice implanted subcutaneously with syngeneic EL-4 lymphoma cells were employed as the host. Oral administration of the extract leads to a reduction of tumor size and prolongation of the host survival time. As judged by plaque-forming cells against T-dependent (sheep erythrocytes) and T-independent (bacterial lipopolysaccharide) antigens, CSE showed to augment the antibody responses. As for the activities of peritoneal macrophages, chemotaxis was dramatically depressed within a few days after EL-4 transplantation up to the end of life, but treatment with CSE at –14, –7, –4, +4, +7 and +10 days after the tumor transplantation augmented the activity about four times stronger than that of control. Phagocytic activity of macrophages was also decreased in tumor-bearing mice treated with cyclophosphamide (100 mg/kg) 3 and 5 days after tumor transplantation. But administration of CSE restored the activity to more than the normal level. The overall efficacy of CSE was tested with protective activity against systemic infection bySalmonella enteritides. The tumor-bearing mice receiving this medicine lived significantly longer than any other groups without CSE.     

Methyl Gallate from Galla rhois Successfully Controls Clinical Isolates of Salmonella Infection in Both In Vitro and In Vivo Systems

Galla rhois is a commonly used traditional medicine for the treatment of pathogenic bacteria in Korea as well as in other parts of Asia. Methyl gallate (MG), a major component of Galla Rhois, exhibits strong antibacterial activity, but its mechanism of action against Salmonella spp. is unclear. In the present study, we investigated the antibacterial actions of MG against Salmonella. The antibacterial activity determined by broth dilution method indicated that the antibacterial activity of MG against Salmonella strains ranged from 3.9 to 125 µg/ml. In vitro bacterial viability test indicated that MG significantly decreased the viability of Salmonella over 40% when combined with ATPase inhibitors. The time-kill curves showed that a combined MG and ATPase inhibitors (DCCD and NaN3) treatment reduced the bacterial counts dramatically after 24 h. Oral administration of MG showed a strong anti-bacterial activity against WS-5 infected BALB/c mice. In contrast to the untreated Salmonella infected control animals, MG treated groups showed no clinical symptoms of the disease, such as lethargy and liver damage. It was observed that MG treatment significantly increased the survival of animals from Salmonella infection, while in untreated groups all animal succumbed to disease by the sixth day post infection. Thus, the present study demonstrates the therapeutic ability of MG against Salmonella infections.     

The effect of bacterially‐dense environments on the development and immune defences of the blowfly Lucilia sericata

Competitive interactions between insects and microbes and the associated cost of development in bacterially‐dense environments are investigated using the blowfly Lucilia sericata (Meigen) (Diptera: Calliphoridae) as a model. The effects of developing in a bacterially‐dense environment are measured by assessing the fitness consequences of competition using the pathogen Staphylococcus aureus. Fitness is quantified in terms of larval survival, puparial development and adult emergence.The influence of bacteria on larval immune defences is investigated using optical density to assess whether antibacterial potency of the larval excretion/secretion changes in response to the degree of contamination of the larval environment. The results obtained demonstrate that bacterial presence has no detrimental effect on survival of L. sericata from egg to adult eclosion, or on puparial size. Additionally, the level of microbial contamination of larvae has no effect on the antibacterial potency of the larval excretion/secretion. These findings confirm that larval antibacterial activity is not induced by the presence of environmental bacteria but is produced constitutively.     

Effect of Long-Term Voluntary Exercise Wheel Running on Susceptibility to Bacterial Pulmonary Infections in a Mouse Model

Regular moderate exercise has been suggested to exert anti-inflammatory effects and improve immune effector functions, resulting in reduced disease incidence and viral infection susceptibility. Whether regular exercise also affects bacterial infection susceptibility is unknown. The aim of this study was to investigate whether regular voluntary exercise wheel running prior to a pulmonary infection with bacteria (P. aeruginosa) affects lung bacteriology, sickness severity and phagocyte immune function in mice. Balb/c mice were randomly placed in a cage with or without a running wheel. After 28 days, mice were intranasally infected with P. aeruginosa. Our study showed that regular exercise resulted in a higher sickness severity score and bacterial (P. aeruginosa) loads in the lungs. The phagocytic capacity of monocytes and neutrophils from spleen and lungs was not affected. Although regular moderate exercise has many health benefits, healthy mice showed increased bacterial (P. aeruginosa) load and symptoms, after regular voluntary exercise, with perseverance of the phagocytic capacity of monocytes and neutrophils. Whether patients, suffering from bacterial infectious diseases, should be encouraged to engage in exercise and physical activities with caution requires further research.     

Antibacterial effect of mesenchymal stem cells against Escherichia coli is mediated by secretion of beta‐ defensin‐ 2 via toll‐ like receptor 4 signalling

Recently, we demonstrated that intratracheal transplantation of human umbilical cord blood‐ derived mesenchymal stem cells (MSCs) attenuates Escherichia (E) coli‐ induced acute lung injury primarily by down‐ modulating inflammation and enhancing bacterial clearance iQn mice. This study was performed to elucidate the mechanism underlying the antibacterial effects of MSCs. The growth of E. coli in vitro was significantly inhibited only by MSCs or their conditioned medium with bacterial preconditioning, but not by fibroblasts or their conditioned medium. Microarray analysis identified significant up‐ regulation of toll‐ like receptors (TLR)‐ 2 and TLR‐ 4, and β‐ defensin 2 (BD2) in MSCs compared with fibroblasts after E. coli exposure. The increased BD2 level and the in vitro antibacterial effects of MSCs were abolished by specific antagonist or by siRNA‐ mediated knockdown of TLR‐ 4, but not TLR‐ 2, and restored by BD2 supplementation. The in vivo down‐ modulation of the inflammatory response and enhanced bacterial clearance, increased BD2 secretion and the resultant protection against E. coli‐ induced pneumonia observed only with MSCs, but not fibroblasts, transplantation in mice, were abolished by knockdown of TLR‐ 4 with siRNA transfection. Our data indicate that BD2 secreted by the MSCs via the TLR‐ 4 signalling pathway is one of the critical paracrine factors mediating their microbicidal effects against E. coli, both in vitro and in vivo. Furthermore, TLR‐ 4 from the transplanted MSCs plays a seminal role in attenuating in vivo E. coli‐ induced pneumonia and the ensuing acute lung injury through both its anti‐ inflammatory and antibacterial effects.     

Effects of fermented aloe vera mixed diet on larval growth of Protaetia brevitarsis seulensis (Kolbe) (coleopteran:Cetoniidae) and protective effects of its extract against CCl4‐induced hepatotoxicity in Sprague–Dawley rats

The present study was conducted to evaluate the efficacy of fermented aloe vera mixed diet on larval growth of Protaetia brevitarsis seulensis (Kolbe) (coleopteran: Cetoniidae) and protective effects of extract of larvae of P. brevitarsis seulensis fed fermented aloe vera mixed diet against Carbon tetrachloride (CCl₄)‐induced hepatotoxicity in Sprague–Dawley rats. To determine whether different diets can affect the larval growth of P. brevitarsis seulensis, six different diets were investigated in the experiment, and the results exhibited that 15% fermented aloe vera with 85% fermented oakwood sawdust was the best diet for larval growth of this insect, followed by 9% fermented aloe vera with 91% fermented oakwood sawdust. Adult male Sprague–Dawley rats (n= 30) were separated into five groups of six each, as follows: control group; CCl₄ group; CCl₄ plus larval extract group (without fermented aloe vera); CCl₄ plus 9% and 15% larval extract groups (with fermented aloe vera). All extract groups were fed with 30 mg/kg extracts of fermented oakwood sawdust only and fermented oakwood sawdust plus 9% and 15% fermented aloe vera, respectively, once every consecutive day, with administration of CCl₄ (1.5 mL/kg, 20% CCl₄ in olive oil) twice a week for 3 weeks. Administration of CCl₄ increased the serum alanine aminotransferase, aspartate aminotranseferase and thiobarbituric acid reactive substance levels in rats and reduced levels of glutathione in the liver. Treatment with extract of larval‐fed fermented aloe vera mixed diet significantly alleviated these changes to nearly normal levels. The histopathological changes induced by CCl₄ were also significantly attenuated by extract of larval‐fed fermented aloe vera mixed diet treatment. The results suggest that the beneficial effect of fermented aloe vera mixed diet on larval growth may be to stimulate the larval life cycle, and 15% larval‐fed fermented aloe vera mixed diet exhibits potent hepatoprotective effects on CCl₄‐induced liver injury in rats, likely due to increased glutathione contents and the inhibition of lipid peroxidation.     

Photodynamic Therapy Using Systemic Administration of 5-Aminolevulinic Acid and a 410-nm Wavelength Light-Emitting Diode for Methicillin-Resistant Staphylococcus aureus-Infected Ulcers in Mice

Bacterial resistance to antibiotics has become a worldwide problem. One potential alternative for bacterial control is photodynamic therapy. 5-aminolevulinic acid is a natural precursor of the photosensitizer protoporphyrin IX. Relatively little is known about the antibacterial efficacy of photodynamic therapy using the systemic administration of 5-aminolevulinic acid; a few reports have shown that 5-aminolevulinic acid exerts photodynamic effects on methicillin-resistant Staphylococcus aureus (MRSA) in vitro. In this study, we evaluated the effectiveness of photodynamic therapy using 5-aminolevulinic acid and a 410-nm wavelength light-emitting diode in vitro and in vivo for the treatment of MRSA. We found that 5-aminolevulinic acid photodynamic therapy with the light-emitting diode had an in-vitro bactericidal effect on MRSA. In vivo, protoporphyrin IX successfully accumulated in MRSA on ulcer surfaces after intraperitoneal administration of 5-aminolevulinic acid to mice. Furthermore, 5-aminolevulinic acid photodynamic therapy accelerated wound healing and decreased bacterial counts on ulcer surfaces; in contrast, vancomycin treatment did not accelerate wound healing. Our findings indicate that 5-aminolevulinic acid photodynamic therapy may be a new treatment option for MRSA-infected wounds.     

Cocculus hirsutus extract inhibits the Xanthomonas oryzae pv. oryzae,the bacterial leaf blight pathogen in rice

Plant-derived natural bactericides and their possible applications in agriculture to control plant bacterial diseases has intensified as this approach has enormous potential to inspire and influence modern agro-chemical research. Naturally occurring and biologically active plant products such as essential oils and organic extracts could be a source of alternative classes of natural biopesticides to serve as templates for new and more effective compounds in controlling plant pathogenic micro-organisms. In the present study, the efficacy of six plants extracts from different solvent system were tested for their antibacterial activity aganist Xanthomonas oryzae pv. oryzae both in vitro and in vivo. Among these extracts, Cocculus hirsutus leaf chloroform extract exhibits significant antibacterial activity against X. oryzae pv. oryzae. Data obtained from the experiments such as minimum inhibitory concentration, effect of C. hirsutus leaf chloroform extract on the incidence of X. oryzae pv. oryzae, phytotoxicity test and effect of C. hirsutus leaf chloroform extract on seed germination and seedling vigour, along with the in vivo experiments under greenhouse conditions showed significant improvement over controls. Thus, the present study demonstrated that the C. hirsutus leaf chloroform extract posses antibacterial activity against bacterial leaf blight pathogen of rice.     

Moxifloxacin modulates inflammation during murine pneumonia

Background

Moxifloxacin is a synthetic antibacterial agent belonging to the fluoroquinolone family. The antimicrobial activity of quinolones against Gram-positive and Gram-negative bacteria is based on their ability to inhibit topoisomerases. Quinolones are described to have immunomodulatory features in addition to their antimicrobial activities. It was the goal of this study to examine whether a short term treatment with moxifloxacin modulates the inflammation during a subsequently induced bacterial infection in an animal model.

Methods

Mice were treated with moxifloxacin or saline for two consecutive days and were subsequently intranasally infected with viable or heat-inactivated bacterial pathogens (Streptococcus pneumoniae, Pseudomonas aeruginosa) for 6 and 24 hours. Measurements of cytokines in the lungs and plasma were performed. Alveolar cells were determined in bronchoalveolar lavage fluits.

Results

The inflammation was increased after the inoculation of viable bacteria compared to inactivated bacteria. Numbers of total immune cells and neutrophils and concentrations of inflammatory mediators (e.g. KC, IL-1β, IL-17A) were significantly reduced in lungs of moxifloxacin-treated mice infected with inactivated and viable bacterial pathogens as compared to infected control mice. Plasma concentrations of inflammatory mediators were significantly reduced in moxifloxacin-treated mice. Immunohistochemistry showed a stronger infiltrate of TNF-α-expressing cells into lungs of saline-treated mice infected with viable P. aeruginosa as compared to moxifloxacin-treated mice.

Conclusions

These data show that in this pneumonia model moxifloxacin has anti-inflammatory properties beyond its antibacterial activity.     

Abelmoschus Manihot ameliorates the levels of circulating metabolites in diabetic nephropathy by modulating gut microbiota in non-obese diabetes mice

Huangkui capsule (HKC), a traditional Chinese medicine, has been used for medication of kidney diseases, including diabetic nephropathy (DN). The current study aimed to evaluate the effects of HKC in the modulation of gut microbiota and the amelioration of metabolite levels by using non-obese diabetes (NOD) mice with DN. The microbiota from three parts of intestines (duodenum, ileum and colon) in NOD mice with and without HKC treatment were analysed using 16S rDNA sequencing techniques. Untargeted metabolomics in plasma of NOD mice were analysed with liquid mass spectrometry. Results showed that HKC administration ameliorated DN in NOD mice and the flora in duodenum were more sensitive to HKC intervention, while the flora in colon had more effects on metabolism. The bacterial genera such as Faecalitalea and Muribaculum significantly increased and negatively correlated with most of the altered metabolites after HKC treatment, while Phyllobacterium, Weissella and Akkermansia showed an opposite trend. The plasma metabolites, mainly including amino acids and fatty acids such as methionine sulfoxide, BCAAs and cis-7-Hexadecenoic acid, exhibited a distinct return to normal after HKC treatment. The current study thereby provides experimental evidence suggesting that HKC may modulate gut microbiota and subsequently ameliorate the metabolite levels in DN.     

Differential immunogenicity and protective efficacy of DNA vaccines expressing proteins of Mycobacterium tuberculosis in a mouse model

BALB/c mice were vaccinated three times (2-week intervals) with plasmid DNA separately encoding antigen Ag85B, ESAT-6 or Ag85A from Mycobacterium tuberculosis. The protective efficacy of these DNA vaccines against intravenous M. tuberculosis H37Rv challenge infection was measured by counting bacterial loads in spleen and lung and recording changes in lung pathology. The splenocyte proliferative response to the corresponding antigens and antigen-specific interferon (IFN)-γ secreted by splenocytes of the vaccinated mice were also detected. We found a clear hierarchy of protective efficacies among the three DNA vaccines tested in this study. Plasmid DNA encoding Ag85A provided the strongest protection and showed the least change in lung pathology, followed by plasmid DNAs encoding Ag85B and ESAT-6. However, DNA-85B reduced comparative bacterial load in lung tissue, as did DNA-85A. Compared to the control group, protective efficacies conferred by different DNA vaccines were consistent with the lymphoproliferative responses to the corresponding antigens as well as the secretions of antigen-specific IFN-γ. Our study demonstrates that both Ag85A and Ag85B are the most promising of the candidate antigens tested for future TB vaccine development.     

The Polysaccharide Capsule of Streptococcus pneumonia Partially Impedes MyD88-Mediated Immunity during Pneumonia in Mice

Toll-like receptors (TLR) and the downstream adaptor protein MyD88 are considered crucial for protective immunity during bacterial infections. Streptococcus (S.) pneumoniae is a human respiratory pathogen and a large majority of clinical pneumococcal isolates expresses an external polysaccharide capsule. We here sought to determine the role of pneumococcal capsule in MyD88-mediated antibacterial defense during S. pneumonia pneumonia. Wild type (WT) and Myd88^-/- mice were inoculated intranasally with serotype 2 S. pneumoniae D39 or with an isogenic capsule locus deletion mutant (D39∆cps), and analysed for bacterial outgrowth and inflammatory responses in the lung. As compared to WT mice, Myd88^-/- mice infected with D39 demonstrated a modestly impaired bacterial clearance accompanied by decreased inflammatory responses in the lung. Strikingly, while WT mice rapidly cleared D39∆cps, Myd88^-/- mice showed 10⁵-fold higher bacterial burdens in their lungs and dissemination to blood 24 hours after infection. These data suggest that the pneumococcal capsule impairs recognition of TLR ligands expressed by S. pneumoniae and thereby partially impedes MyD88-mediated antibacterial defense.     

Ethyl-N-dodecanoyl-l-arginate hydrochloride combats pathogens with low-resistance generation by membrane attack and modifies gut microbiota structure

Ethyl-N-dodecanoyl-l -arginate hydrochloride (LAE, ethyl lauroyl arginate HCl) is a cationic surfactant used as a food preservative with broad-spectrum antibacterial activities. However, its resistance development, influences on gut microbiome and molecular target are unclear. In this study, bacteria were stimulated by LAE for 30 days to test the bacterial resistance. Several infected animal models were used to evaluate the antibacterial effect of LAE in vivo. Mice were orally treated with LAE to test its effect on animal growth. The influence of LAE on mice gut microbiome was analysed by 16S rDNA sequencing. The results indicated that Escherichia coli did not develop resistance to LAE. LAE significantly combats bacterial infection in mice, ducklings and piglets. Moreover, LAE promotes mouse weight gain without changing body composition or reducing animal vitality, and induces lower hepatotoxicity than ampicillin. In the mouse gut microbiome assessment and characterization, LAE modifies host gut microbiota structure. Mechanistically, LAE specifically binds to acidic phospholipids including phosphatidylserine, depolarizes the membrane and disrupts the bacterial membrane followed by bacterial growth inhibition. This study investigates the molecular mechanism of LAE as well as its antibacterial functions in poultry and livestock. Our data suggest LAE is a potential antibacterial agent in animal health.     

Prolactin evokes lactational transmission of larvae in mice infected with Toxocara canis

We investigated the trans-lactational maternal–neonatal transmission of Toxocara canis larvae in mice, with particular interest in the role of prolactin in their migration to the mammary gland. Two female mice were infected with 300 T. canis eggs soon after delivery of 27 offspring. After 1 week of breast-feeding, seven larvae were recovered from 4 of 13 offspring. After 2 weeks of lactation, 101 larvae were recovered from all the remaining offspring. Daily prolactin administration (5 μg) was performed 2 weeks before T. canis infection and continued until 2 weeks after infection in six non-pregnant female mice, which resulted in larval accumulation in the mammary gland. Furthermore, prolactin administration in female mice that had been infected with T. canis 4 weeks prior to prolactin treatment induced migration of larvae into the mammary gland. These findings suggest that prolactin is a promoting factor contributing to lactational transmission of T. canis larvae in mice.     

Inhibition of the type III secretion system by syringaldehyde protects mice from Salmonella enterica serovar Typhimurium

The invasiveness of Salmonella enterica serovar Typhimurium (S. Typhimurium) is closely associated with the Salmonella pathogenicity island (SPI)‐encoded type Ⅲ secretion system (T3SS), which can directly inject a series of effector proteins into eukaryotic cells to enable bacterial infection. In this study, syringaldehyde was identified as an effective inhibitor of the S. Typhimurium T3SS using an effector protein‐lactamase fusion reporter system. Syringaldehyde treatment could inhibit the expression of important effector proteins (SipA, SipB and SipC) at a concentration of 0.18 mM without affecting bacterial growth. Additionally, significant inhibition of bacterial invasion and cellular injury was observed following the syringaldehyde treatment in the co‐infection system of HeLa cells and S. Typhimurium. Furthermore, treatment with syringaldehyde provided systemic protection to mice infected with S. Typhimurium, reducing mortality (40.00%) and bacterial loads and relieving caecal damage and systemic inflammation. The results presented in this study indicate that syringaldehyde significantly affects T3SS activity and is a potential leading compound for treating S. Typhimurium infections.