Protective effects of sodium humate and its zinc and selenium chelate on the oxidative stress, inflammatory, and intestinal barrier damage of Salmonella Typhimurium-challenged broiler chickens.

The objective of this study was to investigate the protective effects and mechanisms of dietary administration of sodium humate (HNa) and its zinc and selenium chelate (Zn/Se-HNa) in mitigating Salmonella Typhimurium (S. Typhi) induced intestinal injury in broiler chickens. Following the gavage of 109 CFU S. Typhi to 240 broilers from 21-d to 23-d aged, various growth performance parameters such as body weight (BW), average daily gain (ADG), average daily feed intake (ADFI), and feed ratio (FCR) were measured before and after infection. Intestinal morphology was assessed to determine the villus height, crypt depth, and chorionic cryptologic ratio. To evaluate intestinal barrier integrity, levels of serum diamine oxidase (DAO), D-lactic acid, tight junction proteins, and the related genes were measured in each group of broilers. An analysis was conducted on inflammatory-related cytokines, oxidase activity, and Nuclear Factor Kappa B (NF-κB) and Nuclear factor erythroid2-related factor 2 (Nrf2) pathway-related proteins and mRNA expression. The results revealed a significant decrease in BW, ADG, and FCR in S. typhi-infected broilers. HNa tended to increase FCR (P = 0.056) while the supplementation of Zn/Se-HNa significantly restored BW and ADG (P < 0.05). HNa and Zn/Se-HNa exhibit favorable and comparable effects in enhancing the levels of serum DAO, D-lactate, and mRNA and protein expression of jejunum and ileal tight junction. In comparison to HNa, Zn/Se-HNa demonstrates a greater reduction in S. Typhi shedding in feces, as well as superior efficacy in enhancing the intestinal morphology, increasing serum catalase (CAT) activity, inhibiting pro-inflammatory cytokines, and suppressing the activation of the NF-κB pathway. Collectively, Zn/Se-HNa was a more effective treatment than HNa to alleviate adverse impact of S. Typhi infection in broiler chickens.

Red osier dogwood extract versus Trimethoprim-sulfadiazine (Part 1). Effects on the growth performance, blood parameters, gut histomorphometry, and Salmonella excretion of broiler chickens orally challenged with Salmonella Enteritidis.

The poultry industry has not been spared from the prevalent incidence of diseases caused by invasive pathogens, especially Salmonella. Due to the pressing need to identify a suitable antibiotic alternative for use in poultry production, this study investigated the efficacy of red osier dogwood (ROD) extract on the growth, blood parameters, gut morphology, and Salmonella excretion in broiler chickens orally challenged with Salmonella Enteritidis (SE). A 4 × 2 factorial experiment was conducted based on 2 main factors, namely dietary treatments, and SE challenge. A total of 404, one-day-old male Ross broiler chicks were randomly assigned to 4 dietary treatments; 1) Negative control (NC), 2) NC + 0.075 ppm of Trimethoprim-sulfadiazine (TMP/SDZ)/kg of diet, 3) NC + 0.3% ROD extract, and 4) NC + 0.5% ROD extract. The absence of SE in the fecal samples obtained from chick delivery boxes was confirmed on d 0. On d 1, half of the birds were orally gavaged with 0.5 mL of phosphate-buffered saline each (noninfected group) and the remaining with 0.5 mL of 3.1 × 105 CFU/mL SE (infected group) in all treatment groups. Dietary treatments were randomly assigned to 8 replicate cages at 6 birds/cage. On 1-, 5-, 12-, and 18-day postinfection (DPI), cloacal fecal samples were collected on the 6 birds/cage to assess SE excretion. Average weight gain (AWG), average feed intake (AFI), feed conversion ratio (FCR), and mortality were determined weekly. On d 21, 10 chickens/treatment were euthanized to perform hematology, gut histomorphometry, serum immunoglobulins G and M (IgG and IgM), and superoxide dismutase measurements. Both ROD extract levels did not affect (P > 0.05) growth performance; however, the SE-infected birds showed increased (P < 0.05) AFI and FCR throughout the experimental period. Regardless of the SE-infection, both ROD extract levels improved (P < 0.05) duodenal villus height: crypt depth compared to other treatments. 0.5% ROD extract improved (P < 0.05) ileal villus width (VW) of noninfected birds and ileal crypt depth of infected birds, but it decreased (P < 0.05) the ileal VW of infected birds, compared to other treatments. The SE-infected birds showed lower (P < 0.05) lymphocytes (L) but increased (P < 0.05) heterophils (H), H:L, and monocytes (MON). Both ROD extract levels did not affect (P > 0.05) white blood cell differential, while dietary 0.3% ROD extract increased (P < 0.05) MON of the birds, regardless of infection model. Regardless of infection model, both TMP/SDZ and 0.5% ROD extract reduced the concentration of IgM in the serum, compared to the control and 0.3% ROD (P = 0.006). Conclusively, both ROD extract levels improved duodenal histomorphology and body defense against SE infection in broiler chickens; however, the 0.3% ROD extract was better.

Antimicrobial and immunomodulatory effects of tannic acid supplementation in broilers infected with Salmonella Typhimurium.

Infection by Salmonella Typhimurium, a food-borne pathogen, can reduce the poultry production efficiency. The objective of this study was to investigate the effects of tannic acid (TA) supplementation on growth performance, Salmonella colonization, gut barrier integrity, serum endotoxin levels, antioxidant capacity, gut health, and immune function in broilers infected with the Salmonella enterica serovar Typhimurium nalidixic acid resistant strain (STNR). A total of 546 one-day-old broilers were arbitrarily allocated into 6 treatments including 1) Sham-challenged control (SCC; birds fed a basal diet and administrated peptone water); 2) Challenged control (CC; birds fed a basal diet and inoculated with 108 STNR); 3) Tannic acid 0.25 (TA0.25; CC + 0.25 g/kg TA); 4) TA0.5 (CC + 0.5 g/kg TA); 5) TA1 (CC + 1 g/kg TA); and 6) TA2 (CC + 2 g/kg TA). On D 7, supplemental TA linearly reduced STNR colonization in the ceca (P < 0.01), and TA1 and TA2 group had significantly lower reduced STNR colonization in the ceca (P < 0.01). On D 7 to 21, average daily gain tended to be linearly increased by supplemental TA (P = 0.097). The serum endotoxin levels were quadratically decreased by supplemental TA on D 21 (P < 0.05). Supplemental TA quadratically increased ileal villus height (VH; P < 0.05), and the TA0.25 group had higher ileal VH compared to the CC group (P < 0.05). Supplemental TA linearly increased percentage of peripheral blood CD8+ T cells on D 18 (P < 0.01). The TA0.5 group had significantly lower lymphocyte numbers compared to the CC groups (P < 0.05). The abundance of monocytes linearly increased with TA supplementation (P < 0.01). Therefore, broilers fed TA had reduced STNR colonization, increased growth performance, decreased serum endotoxin levels, enhanced gut health in the broilers, and stimulated the immune system in broilers infected with STNR. Supplementation of TA (1-2 g/kg) enhanced growth performance and gut health via antimicrobial and immunostimulatory effects in broilers infected with STNR.

Research Note: Virulence gene downregulation and reduced intestinal colonization of Salmonella enterica serovar Typhimurium PHL2020 isolate in broilers by a natural antimicrobial (NeutraPath™).

The reduction in antibiotic growth promoter use in poultry, due to antibiotic resistance concerns, has created a need for natural solutions that control enteric pathogens like Salmonella. One of these natural feed additives, a select blend of essential oils, fatty acids, and an enterosorbent mineral (NeutraPath), was assessed for its effects on the intestinal colonization of Salmonella enterica serovar Typhimurium PHL2020 isolate (ST-PHL2020) in broiler chickens and ST-PHL2020 virulence gene expression. An in vitro digestion model simulating the pH and enzymatic conditions of 3 gastrointestinal compartments (crop, proventriculus, and intestine) was first used to evaluate the antibacterial effects of NeutraPath on ST-PHL2020. For the in vivo study, day-old male broilers (n = 90) were randomly allocated to 1 of 3 groups: control or NeutraPath supplemented at 0.25 or 0.5%. The dose rates were chosen to enable observable statistical effects during high Salmonella challenge. All groups were challenged with ST-PHL2020 (106 cfu/bird) via oral gavage on day 9. Bacterial load and prevalence of ST-PHL2020 were examined in ceca-cecal tonsils, and intestinal permeability was assessed via serum recovery of fluorescein isothiocyanate dextran (FITC-d) 24 h postchallenge. NeutraPath inhibited (P < 0.05) ST-PHL2020 growth in the in vitro digestion model compared to the control at all concentrations and in all compartments other than NeutraPath 0.25% in the crop. In vivo, NeutraPath 0.25 and 0.5% reduced (P < 0.05) the total cfu recovered and total prevalence of ST-PHL2020 in the ceca. The serum FITC-d levels were also reduced (P < 0.05) by NeutraPath. Further, NeutraPath's effects on ST-PHL2020's Salmonella pathogenicity island-1 virulence network development were explored via treating ST-PHL2020 at subinhibitory concentration (1 mg/mL) of NeutraPath in vitro. Compared to the control, NeutraPath downregulated ST-PHL2020 hilA and invF mRNA expression, which further blocked expression of key downstream effectors involved in ST-PHL2020 invasion. Collectively, NeutraPath has the potential to reduce ST-PHL2020 intestinal colonization in broilers and preserve intestinal barrier integrity.

Protective Effects of Zinc on Salmonella Invasion, Intestinal Morphology and Immune Response of Young Pigeons Infected with Salmonella enterica Serovar Typhimurium.

The study aimed to determine the effects of orally supplemental zinc on body weight, Salmonella invasion, serum IgA, intestinal histomorphology, and immune response of Salmonella enterica serovar Typhimurium (S. typhimurium)-challenged young pigeons. A total of 72 healthy White King pigeons (25 days old) with similar weight were randomly assigned to 3 treatments with six replicate cages. The 3 treatments were unchallenged, S. typhimurium-challenged, and S. typhimurium-challenged orally supplemented with 1 mg zinc per bird. Salmonella infection decreased (P < 0.05) the body weight, the bursa index, the serum IgA content, and the villus height/crypt depth ratio in the ileum, but increased the neutrophil proportion (P < 0.001) and the mRNA expressions of IL-1ß and IL-8 in the jejunum (P < 0.05). Orally supplemental zinc reduced (P = 0.007) the bacterial load in the liver and improved (P < 0.05) the body weight, the bursa index, the serum IgA content, the villus height/crypt depth ratio, and the NOD-like receptor family pyrin domain containing 3 (NLRP3) protein expression, as well as tended to increase (P = 0.064) the protein abundance of caspase-1 of the jejunum, but did not alleviate the high level of neutrophil proportion and IL-1ß mRNA expression of the jejunum (P > 0.05). The results indicated that oral zinc supplementation improved the intestinal mucosal morphology and enhanced the immune response, as well as activated caspase-1-dependent cell pyroptosis pathways in the jejunal epithelium, thereby restricting Salmonella invasion of the challenged young pigeons.

Tissue compartmentalization enables Salmonella persistence during chemotherapy.

Antimicrobial chemotherapy can fail to eradicate the pathogen, even in the absence of antimicrobial resistance. Persisting pathogens can subsequently cause relapsing diseases. In vitro studies suggest various mechanisms of antibiotic persistence, but their in vivo relevance remains unclear because of the difficulty of studying scarce pathogen survivors in complex host tissues. Here, we localized and characterized rare surviving Salmonella in mouse spleen using high-resolution whole-organ tomography. Chemotherapy cleared >99.5% of the Salmonella but was inefficient against a small Salmonella subset in the white pulp. Previous models could not explain these findings: drug exposure was adequate, Salmonella continued to replicate, and host stresses induced only limited Salmonella drug tolerance. Instead, antimicrobial clearance required support of Salmonella-killing neutrophils and monocytes, and the density of such cells was lower in the white pulp than in other spleen compartments containing higher Salmonella loads. Neutrophil densities declined further during treatment in response to receding Salmonella loads, resulting in insufficient support for Salmonella clearance from the white pulp and eradication failure. However, adjunctive therapies sustaining inflammatory support enabled effective clearance. These results identify uneven Salmonella tissue colonization and spatiotemporal inflammation dynamics as main causes of Salmonella persistence and establish a powerful approach to investigate scarce but impactful pathogen subsets in complex host environments.

Antimicrobial resistance in non-Typhoidal Salmonella from retail poultry meat by antibiotic usage-related production claims - United States, 2008-2017.

Antimicrobial resistance (AMR) in non-typhoidal Salmonella from poultry is a public health concern. Injudicious use of antibiotics in humans and agriculture fuels the emergence of resistance. The objective of this study was to characterize the prevalence, antibiotic susceptibility profiles and genetic resistance mechanisms of Salmonella isolated from US retail poultry meat samples with and without antibiotic-related claims. We reviewed data from 46,937 poultry meat samples collected from 2008 to 2017 through the FDA NARMS retail meat program. Antibiotic usage claims on the poultry packaging were used to categorize the sample as 'conventionally raised' or 'reduced or no antibiotic use'. The results show that the prevalence of Salmonella in conventional poultry samples (8.6%) was higher than reduced or no antibiotic use poultry samples (5.1%). The odds of resistance to three or more antimicrobial classes (multi-drug resistant) were 2.61 times higher for Salmonella isolates from conventional samples, compared to isolates from reduced antibiotic use samples. The frequency of the aminoglycoside resistance gene, strB, and the beta-lactam resistant gene, blaCMY-2, were higher in isolates from conventional meat. This study suggests that conventionally raised poultry meat was more likely to be contaminated with multi-drug resistant Salmonella, and those Salmonella are more likely to carry genes for antibiotics resistance.

New Polyaminoisoprenyl Antibiotics Enhancers against Two Multidrug-Resistant Gram-Negative Bacteria from Enterobacter and Salmonella Species.

A series consisting of new polyaminoisoprenyl derivatives were prepared in moderate to good chemical yields varying from 32 to 64% according to two synthetic pathways: (1) using a titanium-reductive amination reaction affording a 50/50 mixture of cis and trans isomers and (2) a direct nucleophilic substitution leading to a stereoselective synthesis of the compounds of interest. These compounds were then successfully evaluated for their in vitro antibiotic enhancer properties against resistant Gram-negative bacteria of four antibiotics belonging to four different families. The mechanism of action against Enterobacter aerogenes of one of the most efficient of these chemosensitizing agents was precisely evaluated by using fluorescent dyes to measure outer-membrane permeability and to determine membrane depolarization. The weak cytotoxicity encountered led us to perform an in vivo experiment dealing with the treatment of mice infected with Salmonella typhimurium and affording preliminary promising results in terms of tolerance and efficiency of the polyaminoisoprenyl derivative 5r/doxycycline combination.

Dual role of splenic mononuclear and polymorphonuclear cells in the outcome of ciprofloxacin treatment of Salmonella enterica infections.

OBJECTIVES: To determine the immune cell populations associated with Salmonella enterica serovar Typhimurium before and after ciprofloxacin treatment using a murine model of systemic infection. The effect of depletion of immune cells associating with Salmonella on treatment outcome was also determined. METHODS: We infected mice with a Salmonella enterica serovar Typhimurium strain expressing GFP and used multicolour flow cytometry to identify splenic immune cell populations associating with GFP-positive Salmonella before and after treatment with ciprofloxacin. This was followed by depletion of different immune cell populations using antibodies and liposomes. RESULTS: Our results identified CD11b+CD11chi/lo (dendritic cells/macrophages) and Ly6G+CD11b+ (neutrophils) leucocytes as the main host cell populations that are associated with Salmonella after ciprofloxacin treatment. We therefore proceeded to test the effects of depletion of such populations during treatment. We show that depletion of Ly6G+CD11b+ populations resulted in an increase in the number of viable bacterial cells in the spleen at the end of ciprofloxacin treatment. Conversely, treatment with clodronate liposomes during antimicrobial treatment, which depleted the CD11b+CD11chi/lo populations, resulted in lower numbers of viable bacteria in the tissues. CONCLUSIONS: Our study identified host cells where Salmonella bacteria persist during ciprofloxacin treatment and revealed a dual and opposing effect of removal of Ly6G+CD11b+ and CD11b+CD11chi/lo host cells on the efficacy of antimicrobial treatment. This suggests a dichotomy in the role of these populations in clearance/persistence of Salmonella during antimicrobial treatment.

Dietary supplementation with vitamin C ameliorates the adverse effects of Salmonella Enteritidis-challenge in broilers by shaping intestinal microbiota.

Salmonella Enteritidis (SE) infection is not only a leading cause of poor production performance and compromised animal welfare in broilers but also a potential threat to public health. Two experiments were conducted to evaluate the effects of dietary supplemental vitamin C (VC) on SE challenged-broilers. In experiment 1, one hundred eighty 1-day-old Arbor Acre broilers were randomly allocated into 3 treatments, with 0, 500, or 1,000 mg/kg VC included in the diet. In experiment 2, dietary VC at 0 or 500 mg/kg, with or without SE challenge was applied in a 2 × 2 factorial arrangement in 6 randomized complete blocks. In experiment 1, addition with 500 mg/kg VC increased BW and infectious bursal disease (IBD) titer of broilers on 35 D (P < 0.05), whereas 1,000 mg/kg VC had no effects on the IBD titer (P > 0.05) compared with the control group. In experiment 2, SE challenge depressed BW on 11 and 21 D (P < 0.05 and P = 0.088, respectively), whereas increased mortality and hepatic bacterial translocation (P < 0.05) on 21 D. Further, SE challenge resulted in lower villus height in jejunum, lower microbial richness, and diversity, whereas higher abundance of Enterobacteriaceae in cecum (P < 0.05). Importantly, supplementation with VC increased BW on both 21 and 35 D (P < 0.05 and P = 0.088, respectively) and enhanced the intestinal health by improving villus morphology and microbial structure as indicated by higher cecal microbial richness and Firmicutes to Bacteroidetes ratio, while lower abundance of Enterobacteriaceae (P < 0.05). In addition, birds fed with 500 mg/kg VC in the diet had significantly increased jejunal secretory immunoglobulin A levels, T lymphocytes stimulation index, and serum total antioxidant capability compared with groups without VC (P < 0.05). In conclusion, SE challenge induced lower production performance and higher mortality in broilers. However, dietary supplementation with VC ameliorated SE-caused damage in broilers by improving the intestinal health, partly mediated by shaping the structure of cecal microbiota.

Evaluation of pyroligneous acid as a therapeutic agent against Salmonella in a simulated gastrointestinal tract of poultry.

Pyroligneous acid (PA) was evaluated as a potential alternative to therapeutic antibiotics in poultry. Antimicrobial activity of PA was studied at acidic pH (2.0) and neutral pH (7.0) of the liquid against Salmonella enterica and Lactobacillus acidophilus. Acidic PA gave a MIC value of 0.8% (v/v) and 1.6% (v/v), and neutralized PA gave a MIC value of 1.6% (v/v) and 3.2% (v/v) against S. enterica and L. acidophilus respectively. Acidic PA was evaluated at different concentrations in a simulated poultry digestive tract and cecal fermentation to study its effect on the cecal microflora and fermentation profile. PA at a concentration of 1.6% (v/v) completely inhibited S. enterica and was also found to have a similar effect on lactobacilli count as compared with the control (p = 0.17). Additionally, PA at this concentration was found not to have a significant effect on acetic acid production after 24 h of cecal fermentation (p = 0.20). Graphical abstract.

In vitro synergistic potentials of novel antibacterial combination therapies against Salmonella enterica serovar Typhimurium.

BACKGROUND: The antibiotics generally used in farm animals are rapidly losing their effectiveness all over the world as bacteria develop antibiotic resistance. Like some other pathogenic bacteria multidrug-resistant strains of Salmonella enterica serovar Typhimurium (S. Typhimurium) are also frequently found in animals and humans which poses a major public health concern. New strategies are needed to block the development of resistance and to prolong the life of traditional antibiotics. Thus, this study aimed to increase the efficacy of existing antibiotics against S. Typhimurium by combining them with opportunistic phenolic compounds gallic acid (GA), epicatechin, epicatechin gallate, epigallocatechin and hamamelitannin. Fractional inhibitory concentration indexes (FICI) of phenolic compound-antibiotic combinations against S. Typhimurium were determined. Based on the FICI and clinical importance, 1 combination (GA and ceftiofur) was selected for evaluating its effects on the virulence factors of this bacterium. Viability of Rattus norvegicus (IEC-6) cell in presence of this antibacterial combination was evaluated. RESULTS: Minimum inhibitory concentrations (MICs) of GA, epigallocatechin and hamamelitannin found against different strains of S. Typhimurium were 256, (512-1024), and (512-1024) µg/mL, respectively. Synergistic antibacterial effect was obtained from the combination of erythromycin-epicatechin gallate (FICI: 0.50) against S. Typhimurium. Moreover, additive effects (FICI: 0.502-0.750) were obtained from 16 combinations against this bacterium. The time-kill assay and ultrastructural morphology showed that GA-ceftiofur combination more efficiently inhibited the growth of S. Typhimurium compared to individual antimicrobials. Biofilm viability, and swimming and swarming motilities of S. Typhimurium in presence of GA-ceftiofur combination were more competently inhibited than individual antimicrobials. Viabilities of IEC-6 cells were more significantly enhanced by GA-ceftiofur combinations than these antibacterials alone. CONCLUSIONS: This study suggests that GA-ceftiofur combination can be potential medication to treat S. Typhimurium-associated diarrhea and prevent S. Typhimurium-associated blood-stream infections (e.g.: fever) in farm animals, and ultimately its transmission from animal to human. Further in vivo study to confirm these effects and safety profiles in farm animal should be undertaken for establishing these combinations as medications.

Effect of in feed administration of different butyrate formulations on Salmonella Enteritidis colonization and cecal microbiota in broilers.

Butyrate has been used extensively as a feed additive to improve gut health and to decrease Salmonella colonization in poultry. Salmonella mainly colonizes the ceca so butyrate concentrations should be increased in this gut segment. Discrepancies on the effects of butyrate on Salmonella colonization, described in the scientific literature, could thus be due to butyrate release location effects. In this study, newly developed butyrate formulations were evaluated for their effect on cecal butyrate concentrations and on colonization by Salmonella Enteritidis. In a first trial, broilers were randomly allocated to 7 dietary treatment groups with formulations based on different approaches to modify the butyrate release profile: release from wax matrices based on diffusion/erosion; micropellets supposedly release butyrate around pH 7 in the colon; tributyrin is based on the hydrolysis of esters in the small intestine. Fat-protected butyrate was included as a reference, because of its known effect on reduction of Salmonella colonization. Four days after infection, the number of cfu Salmonella per g cecal content and spleen were determined. Butyrate formulations in a wax matrix significantly reduced the Salmonella colonization in cecal content. In a second trial, wax and fat-protected butyrate treatments were replicated and results from the first trial were confirmed. Compared to the control group a higher proportion of butyrate concentration was observed in ceca for those groups with reduced Salmonella colonization. This was associated with a beneficial shift in the cecal microbiota. In conclusion, formulations that increase cecal butyrate concentrations are superior in protecting against Salmonella Enteritidis colonization.

Evaluation of in-vivo anti-Salmonella activity of Uvaria chamae, Lantana camara and Phyllantus amarus used in Benin, West Africa.

BACKGROUND: Uvaria chamae (Annonaceae), Phyllantus amarus (Phyllantaceae) and Lantana camara (Verbenaceae) are empirically alleged to be used as Beninese medicinal plants in the treatment of salmonellosis. This study aimed to produce scientific data on in vitro and in vivo efficacy of Uvaria chamae, Lantana camara and Phyllantus amarus on multiresistant Salmonella spp isolated in Benin. RESULTS: After performing in vitro tests on aqueous and ethanolic extracts of these plants, only the aqueous extract of Uvaria chamae (leaves) showed the best anti-Salmonella's activity and was used for this in vivo experiment. The induction of salmonellosis revealed 9 × 108 CFU/ml was the optimal concentration triggering and maintaining symptoms in chicks. This infective concentration was used for in vivo assessment. Twenty-four hours post inoculation, the symptoms of salmonellosis (wet cloaca, diarrhea stools and somnolence) were observed in infected groups. After 7 days of treatment, the reduction of bacterial load at 100 mg/L, 200 mg/L, 400 mg/L of the extract was respectively 85%, 52.38% and 98% for Uvaria chamae, Phyllantus amarus and Lantana camara in the chick's groups infected with Salmonella Typhimurium ATCC 14028. On the other hand, colistin completely cancelled the bacterial load (reduction rate of 100%). With the groups infected with Salmonella spp (virulent strain), the reduction rate of bacterial load at 100 mg/L, 200 mg/L, 400 mg/L of extract was 0%, 98.66%, and 99.33%. The extracts at 200 and 400 mg/L were more active than colistin, which reduced the bacterial load by 33.33%. The toxicity tests did not show any negative effect of Colistin and the Uvaria chamae's extract on the biochemical and hematological parameters of the chicks. CONCLUSION: The aqueous extract of Uvaria chamae is active in vitro and in vivo on multiresistant strains of Salmonella enterica. This plant is a good candidate for the development of an improved traditional medicine for the management of salmonellosis.

Nickel chelation therapy as an approach to combat multi-drug resistant enteric pathogens.

The nickel (Ni)-specific chelator dimethylglyoxime (DMG) has been used for many years to detect, quantitate or decrease Ni levels in various environments. Addition of DMG at millimolar levels has a bacteriostatic effect on some enteric pathogens, including multidrug resistant (MDR) strains of Salmonella Typhimurium and Klebsiella pneumoniae. DMG inhibited activity of two Ni-containing enzymes, Salmonella hydrogenase and Klebsiella urease. Oral delivery of nontoxic levels of DMG to mice previously inoculated with S. Typhimurium led to a 50% survival rate, while 100% of infected mice in the no-DMG control group succumbed to salmonellosis. Pathogen colonization numbers from livers and spleens of mice were 10- fold reduced by DMG treatment of the Salmonella-infected mice. Using Nuclear Magnetic Resonance, we were able to detect DMG in the livers of DMG-(orally) treated mice. Inoculation of Galleria mellonella (wax moth) larvae with DMG prior to injection of either MDR K. pneumoniae or MDR S. Typhimurium led to 40% and 60% survival, respectively, compared to 100% mortality of larvae infected with either pathogen, but without prior DMG administration. Our results suggest that DMG-mediated Ni-chelation could provide a novel approach to combat enteric pathogens, including recalcitrant multi-drug resistant strains.

Pharmacokinetic and pharmacodynamic integration of enrofloxacin against Salmonella Enteritidis after administering to broiler chicken by per-oral and intravenous routes.

It is crucial to optimize the dose of fluoroquinolones to avoid antibiotic resistance and to attain clinical success. We undertook this study to optimize the dose of enrofloxacin against Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) in chicken by assessing its pharmacokinetic/pharmacodynamic (PK/PD) indices. The antibacterial activities of enrofloxacin against S. Enteritidis were evaluated. After administering 10 mg/kg body weight (b.w.) of enrofloxacin to broiler chickens of both sexes by intravenous (IV) and peroral (PO) routes, blood samples were drawn at different intervals and enrofloxacin concentrations in plasma were determined. PK/PD indices were calculated by integrating the PK and PD data. The elimination half-lives (T1/2), time required to reach peak concentration (Tmax), peak concentration (Cmax), and area under curve (AUC) after administering enrofloxacin by PO and IV routes were 25.84 ± 1.40 h, 0.65 ± 0.12 h, 3.82 ± 0.59 µg/mL, and 20.84 ± 5.0 µg·h/mL, and 12.84 ± 1.4 h, 0.22 ± 0.1 h, 6.74 ± 0.03 µg/mL, and 21.13 ± 0.9 µg.h/mL, respectively. The bioavailability of enrofloxacin was 98.6% ± 8.9% after PO administration. The MICs of enrofloxacin were 0.0625-1 µg/mL against S. Enteritidis strains, and the MIC50 was 0.50 µg/mL. The Cmax/MIC50 were 7.64 ± 0.2 and 13.48 ± 0.7 and the 24 h AUC/MIC50 were 41.68 ± 0.1 and 42.26 ± 0.3 after administering the drug through PO and IV routes, respectively. The data in this study indicate that the application of 50 mg/kg b.w. of enrofloxacin to chicken through PO and IV routes with a dosing interval of 24 h can effectively cure S. Enteritidis infection, indicating the need for a 5-fold increase in the recommended dosage of enrofloxacin in chicken.

Evaluation of the antimicrobial and intestinal integrity properties of boric acid in broiler chickens infected with Salmonella enteritidis: Proof of concept.

The objectives of the present study were to evaluate the antimicrobial effect of boric acid (BA) on Salmonella enteritidis colonization, intestinal permeability, total intestinal IgA levels, and cecal microbiota composition in broiler chickens. For this purpose, sixty day-old-chicks were randomly allocated to one of two groups: 1) non-treated control group and 2) 0.1% (w/w) BA in feed. All chicks were challenged with 104 cfu of S. Enteritidis per bird at 1-d old. On day 3 and 10 post-challenge, samples of crop and ceca-cecal tonsils (CCT) were aseptically collected to evaluate overall aerobic and lactic acid bacteria, as well as S. Enteritidis recovery. Blood and intestinal samples were also collected to evaluate intestinal permeability and total intestinal IgA production, respectively. On day 10 post-challenge, the concentration of S. Enteritidis in crop and CCT significantly decreased (P < .05) by 2.60 log10 and 5.26 log10, respectively, in the BA group compared to the control group. Furthermore, chickens treated with 0.1% BA had a significant reduction in serum fluorescein isothiocyanate dextran (FITC-d) concentration and lower total intestinal IgA levels when compared to the control group. Interestingly, in the microbiota analysis, only the abundance of Actinobacteria phylum was significantly lower in the BA group in comparison with the control group and significant differences in beta diversity were also observed between comparing groups. The results of the present study suggest that BA could maintain intestinal homeostasis, as well as the balance in the microbiota due to its effectiveness in controlling S. Enteritidis infection.

The Influence of Feed-Supplementation with Probiotic Strain Lactobacillus reuteri CCM 8617 and Alginite on Intestinal Microenvironment of SPF Mice Infected with Salmonella Typhimurium CCM 7205.

Alginite is a non-ore raw material arising by fossilization of accumulated organic (algae) and inorganic material, particularly clay, carbonates, quartz, and amorphous modification of silicic acid in the aqueous environment. Humic acids as a component of organic portion of alginite are known for very good buffering ability which allows them to stabilise pH throughout the digestion system of animals, stimulate receptors of the immune system in intestinal villi against pathogenic bacteria, and support proliferation and activity of beneficial bacteria (lactobacilli, bifidobacteria, and similar). Our investigations focused on the influence of a probiotic strain in combination with alginite on intestinal microenvironment of SPF mice infected with Salmonella Typhimurium. The 66 female mice (BALB/c) used in our study were divided to four experimental groups, control NC1, control NC2 (alginite), IC (alginite + Salmonella Typhimurium CCM 7205NAL), LAB (Lact. reuteri CCM 8617 + alginite + Salm. Typhimurium CCM 7205NAL). The group supplemented with Lact.reuteri CCM 8617 and alginite showed significant reduction in growth of Salm. Typhimurium in mice faeces at 24 and 72 h (P < 0.001) post infection. The supplementation of additives affected positively also nitrogen, enzymatic, hepatic and energy metabolism of mice. The demonstrable positive influence of additives alleviated the negative impact of Salm. Typhimurium infection on the morphology investigated in the jejunum and ileum of LAB group of mice. The livers of mice treated with both alginite and Lact.reuteri CCM 8617 showed marked reduction of overall inflammation, hepatocyte necrosis and size of typhoid nodules.

The effect of some natural alternative to antibiotics on growth and changes in intestinal histology in broiler exposed to Salmonella challenge.

This study was conducted to find the effect of different feed additives on the production performance and intestinal histology in Salmonella challenged birds. A total of 600 day-old-broiler chicks (Ross 308) were assignment to 10 treatments. Each treatment was further divided into 10 replicates. The chicks were randomly divided into one of the following 10 treatments as follow: Negative control; positive control infected with Salmonella enterica subsp. typhimurium; T1, infected + avilamycin at the rate of 0.2 g/kg; T2, infected + probiotic having viable spores (2 × 107 CFU/g) of Bacillus subtilis (ATCC PTA-6737); T3, infected + Sanguinarine consisting of benzo phenanthridine alkaloids from Macleaya cordata; T4, B. subtilis (ATCC PTA-6737) + Sanguinarine; T5, infected + B. subtilis 500 g/T of feed (1.2 × 106 cfu/g); T6, prebiotic, Saccharomyces boulardii (1 × 108cfu/g); T7, infected + oregano at the rate of 1 g/kg; T8, infected + thermally processed clay calcium montmorillonite. The results showed that feed intake was significantly (P < 0.01) high in negative control and T2 compared to the positive control. Body weight gain was significantly (P < 0.01) higher in negative control and significantly (P < 0.05) low in T8. Feed conversion ratio was significantly (P < 0.05) high in negative control and significanlty (P < 0.05) high in T6. Similarly, PEF was also significantly (P < 0.05) high in negative control and significantly (P < 0.05) low in positive control and T8. Villus width was significantly (P < 0.05) high in negative control followed by T8. Dietary supplementation of different feed additives may be useful in broiler chicks challenged with Salmonella infection.

Baicalin protects mice against Salmonella typhimurium infection via the modulation of both bacterial virulence and host response.

BACKGROUND: The worsening problems of antibiotic resistance prompt the need for alternative strategies. Baicalin, which is isolated from Scutellaria baicalensisi, has been demonstrated to exhibit anti-inflammatory, anti-virulence and antimicrobial effects. Salmonella typhimurium is an important foodborne pathogenic bacteriaum that causes gastrointestinal disease in humans and many animals. PURPOSE: The aim of this study was to investigate the effects of baicalin on S. typhimurium infection in mice and its possible mechanism in vitro. STUDY DESIGN: To evaluate the effect of baicalin in vivo, mice were orally administered of baicalin, and then were infected by an intragastric administration of S. typhimurium. The minimal inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of baicalin, baicalein, and oroxylin A against S. typhimurium were detected under the guides of the Clinical and Laboratory Standards Institute. In vitro, Caco-2 cells were infected with S. typhimurium in the presence or absence of baicalin, baicalein, and oroxylin A at sub-MICs. METHODS: In the in vivo experiment, the body weight loss, the serum levels of TNFα,  IL-6, and lactic dehydrogenase (LDH), the pathological changes of the caecum and the caecum bacterial burdens were examined. The MICs and MBCs of baicalin, baicalein, and oroxylin A against S. typhimurium were detected by two-fold serial dilutions. In vitro, Caco-2 cells were infected with S. typhimurium, and the invasion capacity, TNFα, nitrate, and LDH were analysed. The transcription levels of Salmonella pathogenicity island 1 virulence associated genes (sopB, sopE, sopE2) of S. typhimurium in the presence of baicalin, baicalein, and oroxylin A were detected by qRT-PCR. RESULTS: Our results showed that baicalin significantly decreased the body weight loss, the serum levels of TNFα,  IL-6, and LDH, and the caecum bacterial burdens of mice challenged with S. typhimurium. Histological examination showed that baicalin decreased the lesion in the caecum of S. typhimurium-infected mice. MICs and MBCs of baicalin, and oroxylin A. against S. typhimurium were > 128 µg/ml. MICs and MBCs of baicalein against S. typhimurium were 64 µg/ml, and > 128 µg/ml, respectively. Pretreatment of Caco-2 cells or S. typhimurium with baicalin, baicalein, and oroxylin A significantly inhibited the invasion of Caco-2 cells by S. typhimurium in a dose-dependent manner. Sub-MICs of baicalin, baicalein, and oroxylin A also significantly decreased the levels of TNFα, nitrate, and LDH from S. typhimurium-infected Caco-2 cells. Moreover, the transcription levels of sopB, sopE, and sopE2 were significantly suppressed by baicalin, baicalein, and oroxylin A. CONCLUSIONS: These results demonstrated that baicalin is a promising agent for the prevention of S. typhimurium infection via the modulation of both bacterial virulence and host response.