Oral Treatment with Saccharomyces cerevisiae CNCM I-3856 Mitigates the Inflammatory Response Experimentally Induced by Salmonella enterica subsp. enterica Serovar Typhimurium in Mice.

Salmonella spp. are intracellular, Gram-negative pathogens responsible for a range of diarrheal diseases, which can present either as self-limited (gastroenteritis) or as a systemic form (typhoid fever), characterizing a serious public health problem. In this study, we investigated the therapeutic effects of oral administration of Saccharomyces cerevisiae CNCM I-3856 in a murine model infected with Salmonella Typhimurium (ST). This yeast species has previously demonstrated the potential to support immune function and reduce inflammation and the ability to exert antimicrobial activity, which is important considering the increasing prevalence of antibiotic-resistant bacteria. Our findings revealed that mice infected with ST and only treated with sterile saline exhibited a higher mortality rate and body weight loss. In contrast, mice treated with I-3856 showed a notable reduction in these adverse outcomes. The yeast demonstrated a high capacity for co-aggregation with the pathogen. Furthermore, the significant amounts of yeast found in the feces of treated mice suggest that intestinal colonization was effective, which was associated with several beneficial effects, including reduced intestinal permeability, which likely limits bacterial translocation to extraintestinal organs. Additionally, the administration of I-3856 reduced levels of sIgA and resulted in a decrease in the recruitment of neutrophils and eosinophils to infection sites, indicating a modulation of the inflammatory response. Histological analyses showed attenuated liver and intestinal lesions in the yeast-treated mice, corroborating the protective effects of the yeast. In conclusion, the results suggest that S. cerevisiae CNCM I-3856 has the potential to control the inflammatory response experimentally induced by S. Typhimurium when administered to mice.

Presence of integrons and their correlation with multidrug resistance in Salmonella enterica serovar Typhimurium: Exploratory systematic review / Presencia de integrones y su correlación con la multirresistencia en Salmonella enterica serovar Typhimurium: revisión sistemática exploratoria.

In Salmonella enterica serovar Typhimurium (Typhimurium), multidrug resistance is associated with integrons carrying resistance genes dispersed by mobile genetic elements. This exploratory systematic review sought to identify integron types and their resistance genes in multidrug resistance Typhimurium isolates. We used Medline, PubMed, SciELO, ScienceDirect, Redalyc, and Google Scholar as motor searchers for articles in Spanish or English published between 2012 and 2020, including the keywords "integrons", "antibiotic resistance", and "Salmonella Typhimurium". We included 38 articles reporting multidrug resistance up to five antibiotic families. Class 1 integrons with aadA2 and blaPSE-1 gene cassettes were predominant, some probably related to the Salmonella genomic island 1. We did not find studies detailing class 1 and 2 integrons in the same isolate, nor class 3 integrons reported. The presence of integrons largely explains the resistance profiles found in isolates from different sources in 15 countries.

La multirresistencia a los antibióticos en Salmonella enterica serovar Typhimurium (Typhimurium) se asocia con integrones que portan genes de resistencia y que son dispersados por elementos genéticos móviles. En esta revisión sistemática exploratoria, se buscó identificar los tipos de integrones y sus genes de resistencia en aislamientos de Typhimurium multirresistentes a antibióticos. Se realizó una búsqueda de artículos en Medline, PubMed, SciELO, ScienceDirect, Redalyc y Google Académico, publicados entre el 2012 y el 2020, en español o inglés, con las palabras claves: "integrons", "antibiotic resistance" y "Salmonella Typhimurium". En el análisis se incluyeron 38 artículos que reportaron multirresistencia a cinco familias de antibióticos. Los integrones de clase 1 con casetes de genes aadA2 y blaPSE-1 fueron los predominantes, algunos probablemente relacionados con la isla genómica de Salmonella 1. No se encontraron integrones de clase 1 y 2 en un mismo aislamiento, ni se reportaron integrones de clase 3. La presencia de integrones explica en gran medida los perfiles de resistencia encontrados en aislamientos de diferentes fuentes de 15 países.

Transcriptional regulator MarT negatively regulates MarT-regulated motility gene I, a new gene involved in invasion and virulence of Salmonella enterica.

The speciation of Salmonella occurred by acquisition of genomic islands from other bacterial species and continued to diverge into subspecies and serovars with diferent range of host. S. enterica serovar Typhimurium (STM) is a generalist pathogen infecting hosts that include birds, mice, and humans, whilst S. enterica serovar Typhi (STY) is a restricted-host pathogen, infecting only humans. Despite their ranges of hosts, STM and STY possess 97-98% identity. Gain of genes by horizontal transference and loss of genes by mutations, are believed essential for differentiation of Salmonella. Salmonella pathogenicity island 3 (SPI-3) is an example combining these two processes. SPI-3 encodes misL and marT, among other genes. In STM, misL is required for gut colonization. Furthermore, protein MarT, positively regulates expression of misL by binding to misL-promoter. On the other hand, in SPI-3 of STY, marT and misL are pseudogenes. Interestingly, the gene t3766 (gene involved in resistance to H2O2) is present only in STY and is negatively regulated when marT STM is heterologously expressed in STY. Based on the view that MarT might regulate genes implicated in virulence, this work searched for new genes regulated by MarT. In silico searches for possible MarT target genes were performed, and 4 genes were selected for further analysis as they contained at least 2 copies of the consensus MarT-binding sequence in their promoters. Mutating marT in STM or heterologously expressing marT STM in STY confirmed that MarT negatively regulates ORF STY1408 or STM14_2003, its homologue in STM. STY1408 encodes for a putative protein with homology to methyl accepting chemotaxis proteins, which participate in chemotaxis and motility. Therefore, STY1408 was named mrmI (MarT-regulated motility gene I). Motility assays confirmed that the product of mrmI modulates motility. In addition, in vitro infection of cells with STM and STY mutants in mrmI reduces association with cells at 1, 3 and 24 h post-infection. Oral infection of mice showed that a mrmI null mutant was defective in producing systemic disease. Therefore, we conclude that MarT regulated mrmI, is involved in virulence of Salmonella. While pseudogenization of marT might modulate the fitness of narrow host range STY.

Deletions of ttrA and pduA genes in Salmonella enterica affect survival within chicken-derived HD-11 macrophages.

In mammals, enteric salmonellas can use tetrathionate (ttr), formed as a by-product from the inflammatory process in the intestine, as electron acceptor in anaerobic respiration, and it can fuel its energy metabolism by degrading the microbial fermentation product 1,2-propanediol. However, recent studies have shown that this mechanism is not important for Salmonella infection in the intestine of poultry, while it prolongs the persistence of Salmonella at systemic sites in this species. In the current study, we show that ΔttrApduA strains of Salmonella enterica have lower net survival within chicken-derived HD-11 macrophages, as CFU was only 2.3% (S. Enteritidis ΔttrApduA), 2.3% (S. Heidelberg ΔttrApduA), and 3.0% (S. Typhimurium ΔttrApduA) compared to wild-type strains after 24 h inside HD-11 macrophage cells. The difference was not related to increased lysis of macrophages, and deletion of ttrA and pduA did not impair the ability of the strains to grow anaerobically. Further studies are indicated to determine the reason why Salmonella ΔttrApduA strains survive less well inside macrophage cell lines.

Attenuated mutants of Salmonella enterica Typhimurium mediate melanoma regression via an immune response.

The lack of effective treatment options for an increasing number of cancer cases highlights the need for new anticancer therapeutic strategies. Immunotherapy mediated by Salmonella enterica Typhimurium is a promising anticancer treatment. Candidate strains for anticancer therapy must be attenuated while retaining their antitumor activity. Here, we investigated the attenuation and antitumor efficacy of two S. enterica Typhimurium mutants, ΔtolRA and ΔihfABpmi, in a murine melanoma model. Results showed high attenuation of ΔtolRA in the Galleria mellonella model, and invasion and survival in tumor cells. However, it showed weak antitumor effects in vitro and in vivo. Contrastingly, lower attenuation of the attenuated ΔihfABpmi strain resulted in regression of tumor mass in all mice, approximately 6 days after the first treatment. The therapeutic response induced by ΔihfABpmi was accompanied with macrophage accumulation of antitumor phenotype (M1) and significant increase in the mRNAs of proinflammatory mediators (TNF-α, IL-6, and iNOS) and an apoptosis inducer (Bax). Our findings indicate that the attenuated ΔihfABpmi exerts its antitumor activity by inducing macrophage infiltration or reprogramming the immunosuppressed tumor microenvironment to an activated state, suggesting that attenuated S. enterica Typhimurium strains based on nucleoid-associated protein genes deletion could be immunotherapeutic against cancer.

A natural approach to combating antibiotic-resistant pathogens in livestock: Hibiscus sabdariffa-derived hibiscus acid as a promising solution.

We examined the antibacterial efficacy of streptomycin, hibiscus acid, and their combination against multidrug-resistant Shiga-toxin-producing Escherichia coli (STEC) and Salmonella Typhimurium in mice. We determined the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for streptomycin, hibiscus acid, and their combination against STEC and Salmonella. Fifteen sets of six mice in each set were utilised: six groups were orally exposed to 4 log10 colony forming units (CFUs) of S. Typhimurium and another six to STEC, and three acted as the controls. Six hours post-inoculation, specific groups of mice received either oral solutions containing hibiscus acid at 5 and 7 mg/ml; streptomycin at 50 and 450 µg/ml; hibiscus acid/streptomycin (5 mg/ml hibiscus acid and 50 µg/ml streptomycin); or isotonic saline. The study determined the MIC and MBC of 7 mg/ml of hibiscus acid; 300 and 450 µg/ml of streptomycin; and two concentrations of hibiscus/streptomycin (3 mg/ml / 20 µg/ml and 5 mg/ml / 50 µg/ml). Interestingly, the mice that were infected and subsequently treated with hibiscus acid at 7 mg/ml alone or in conjunction with streptomycin did not have either STEC or Salmonella in their faecal samples, and none of the mice died. In contrast, the untreated mice and those exclusively treated with streptomycin had the pathogens present in their stool, leading to the mortality of all the subjects.

Presencia de integrones y su correlación con la multirresistencia en Salmonella entérica serovar Typhimurium: revisión sistemática exploratoria / Presence of integrons and their correlation with multidrug resistance in Salmonella entérica serovar Typhimurium: Exploratory systematic review

RESUMEN La multirresistencia a los antibióticos en Salmonella entérica serovar Typhimurium (Typhimurium) se asocia con integrones que portan genes de resistencia y que son dispersados por elementos genéticos móviles. En esta revisión sistemática exploratoria, se buscó identificar los tipos de integrones y sus genes de resistencia en aislamientos de Typhimurium multirresistentes a antibióticos. Se realizó una búsqueda de artículos en Medline, PubMed, SciELO, ScienceDirect, Redalyc y Google Académico, publicados entre el 2012 y el 2020, en español o inglés, con las palabras claves: "integrons", "antibiotic resistance" y "Salmonella Typhimurium". En el análisis se incluyeron 38 artículos que reportaron multirresistencia a cinco familias de antibióticos. Los integrones de clase 1 con casetes de genes aadA2 y blaPSE-1 fueron los predominantes, algunos probablemente relacionados con la isla genómica de Salmonella 1. No se encontraron integrones de clase 1 y 2 en un mismo aislamiento, ni se reportaron integrones de clase 3. La presencia de integrones explica en gran medida los perfiles de resistencia encontrados en aislamientos de diferentes fuentes de 15 países.

ABSTRACT In Salmonella enterica serovar Typhimurium (Typhimurium), multidrug resistance is associated with integrons carrying resistance genes dispersed by mobile genetic elements. This exploratory systematic review sought to identify integron types and their resistance genes in multidrug resistance Typhimurium isolates. We used Medline, PubMed, SciELO, ScienceDirect, Redalyc, and Google Scholar as motor searchers for articles in Spanish or English published between 2012 and 2020, including the keywords "integrons", "antibiotic resistance", and "Salmonella Typhimurium". We included 38 articles reporting multidrug resistance up to five antibiotic families. Class 1 integrons with aadA2 and blaPSE-1 gene cassettes were predominant, some probably related to the Salmonella genomic island 1. We did not find studies detailing class 1 and 2 integrons in the same isolate, nor class 3 integrons reported. The presence of integrons largely explains the resistance profiles found in isolates from different sources in 15 countries.

Inactivation of Salmonella Typhimurium, Escherichia coli, and Staphylococcus aureus in Tilapia Fillets (Oreochromis niloticus) with Lactic and Peracetic Acid through Fogging and Immersion.

This study investigated the antimicrobial effects of lactic acid (LA) (3%) and peracetic acid (PA) (300 ppm) on tilapia fillets (Oreochromis niloticus) by fogging (15 min) or by immersion (2 s) in a pool of Escherichia coli (NEWP 0022, ATCC 25922, and a field-isolated strain), Staphylococcus aureus (ATCC 25923 and a field-isolated strain), and Salmonella Typhimurium (ATCC 13311 and ATCC 14028), as well as the effects on the physicochemical characteristics of the fillets. Fogging was effective and the best application method to control S. Typhimurium regardless of the acid used, promoting reductions of 1.66 and 1.23 log CFU/g with PA and LA, respectively. Regarding E. coli, there were significant reductions higher than 1 log CFU/g, regardless of the treatment or acid used. For S. aureus, only immersion in PA showed no significant difference (p < 0.05). For other treatments, significant reductions of 0.98, 1.51, and 1.17 log CFU/g were observed for nebulized PA, immersion, and LA fogging, respectively. Concerning the pH of the samples, neither of the acids used differed from the control. However, treatments with LA, and fogging with PA, reduced the pH compared to immersion in PA. As for color parameters, L* and a* values showed changes regardless of the acid or method used, resulting in an improved perception of fillet quality. These results indicate that fogging and immersion are alternatives for reducing S. Typhimurium, E. coli, and S. aureus in tilapia fillets.

Interaction of beauvericin in combination with antibiotics against methicillin-resistant Staphylococcus aureus and Salmonella typhimurium.

Multidrug resistance in bacteria is a major challenge worldwide, increasing both mortality by infections and costs for the health systems. Therefore, it is of utmost importance to find new drugs against resistant bacteria. Beauvericin (BEA) is a mycotoxin produced by entomopathogenic and other fungi of the genus Fusarium. Our work determines the effect of BEA combined with antibiotics, which has not been previously explored. The combination analysis included different antibiotics against non-methicillin-resistant Staphylococcus aureus (NT-MRSA), methicillin-resistant Staphylococcus aureus (MRSA), and Salmonella typhimurium. BEA showed a synergy effect with oxacillin with a fractional inhibitory concentration index (FICI) = 0.373 and an additive effect in combination with lincomycin (FICI = 0.507) against MRSA. In contrast, it was an antagonist when combined with ciprofloxacin against S. typhimurium. We propose BEA as a molecule with the potential for the development of new therapies in combination with current antibiotics against multidrug-resistant bacteria.

Salmonella enterica and outer membrane vesicles are current and future options for cancer treatment.

Conventional cancer therapies have many limitations. In the last decade, it has been suggested that bacteria-mediated immunotherapy may circumvent the restrictions of traditional treatments. For example, Salmonella enterica is the most promising bacteria for treating cancer due to its intrinsic abilities, such as killing tumor cells, targeting, penetrating, and proliferating into the tumor. S. enterica has been genetically modified to ensure safety and increase its intrinsic antitumor efficacy. This bacterium has been used as a vector for delivering anticancer agents and as a combination therapy with chemotherapy, radiotherapy, or photothermic. Recent studies have reported the antitumor efficacy of outer membrane vesicles (OMVs) derived from S. enterica. OMVs are considered safer than attenuated bacteria and can stimulate the immune system as they comprise most of the immunogens found on the surface of their parent bacteria. Furthermore, OMVs can also be used as nanocarriers for antitumor agents. This review describes the advances in S. enterica as immunotherapy against cancer and the mechanisms by which Salmonella fights cancer. We also highlight the use of OMVs as immunotherapy and nanocarriers of anticancer agents. OMVs derived from S. enterica are innovative and promising strategies requiring further investigation.

Development of recombinant subunit vaccine targeting InvH protein of Salmonella Typhimurium and evaluation of its immunoprotective efficacy against salmonellosis.

Salmonella Typhimurium is the most prevalent non-host specific Salmonella serovars and a major concern for both human and animal health systems worldwide contributing to significant economic loss. Type 3 secretion system (T3SS) of Salmonella plays an important role in bacterial adherence and entry into the host epithelial cells. The product of invH gene of Salmonella is an important component of the needle complex of the type 3 secretion system. Hence, the present study was undertaken to clone and express the 15 kDa InvH surface protein of Salmonella Typhimurium in an E. coli host and to evaluate its immune potency in mice. The purified recombinant InvH (r-InvH) protein provoked a significant (p < 0.01) rise in IgG in the inoculated mice. The immunized mice were completely (100%) protected against the challenge dose of 107.5 LD50, while protection against challenge with the same dose of heterologous serovars was 90%. The bacterin-vaccinated group showed homologous protection of 60% against all three serovars. Findings in this study suggest the potential of the r-InvH protein of S. Typhimurium as an effective vaccine candidate against Salmonella infections.

Oregano Essential Oil versus Conventional Disinfectants against Salmonella Typhimurium and Escherichia coli O157:H7 Biofilms and Damage to Stainless-Steel Surfaces.

This study compared the effect of oregano essential oil versus sodium hypochlorite, hydrogen peroxide, and benzalkonium chloride against the viability of adhered Salmonella Typhimurium and Escherichia coli O157:H7 on 304 stainless steel. Oregano essential oil was effective in disrupting the biofilms of both bacteria at concentrations ranging from 0.15 to 0.52 mg mL-1. In addition, damage to stainless-steel surfaces following disinfection treatments was assessed by weight loss analysis and via visual inspection using light microscopy. Compared to the other treatments, oregano oil caused the least damage to stainless steel (~0.001% weight loss), whereas sodium hypochlorite caused the most severe damage (0.00817% weight loss) when applied at 0.5 mg mL-1. Moreover, oregano oil also had an apparent protective impact on the stainless steel as weight losses were less than for the control surfaces (distilled water only). On the other hand, sodium hypochlorite caused the most severe damage to stainless steel (0.00817% weight loss). In conclusion, oregano oil eliminated monoculture biofilms of two important foodborne pathogens on 304 stainless-steel surfaces, while at the same time minimizing damage to the surfaces compared with conventional disinfectant treatments.

Invasive non-typhoidal Salmonella (iNTS) aminoglycoside-resistant ST313 isolates feature unique pathogenic mechanisms to reach the bloodstream.

Invasive non-typhoidal Salmonella (iNTS) from the clonal type ST313 (S. Typhimurium ST313) is the primary cause of invasive salmonellosis in Africa. Recently, in Brazil, iNTS ST313 strains have been isolated from different sources, but there is a lack of understanding of the mechanisms behind how these gut bacteria can break the gut barrier and reach the patient's bloodstream. Here, we compare 13 strains of S. Typhimurium ST313, previously unreported isolates, from human blood cultures, investigating aspects of virulence and mechanisms of resistance. Initially, RNAseq analyses between ST13-blood isolate and SL1344 (ST19) prototype revealed 15 upregulated genes directly related to cellular invasion and replication, such as sopD2, sifB, and pipB. Limited information is available about S. Typhimurium ST313 pathogenesis and epidemiology, especially related to the global distribution of strains. Herein, the correlation of strains isolated from different sources in Brazil was employed to compare clinical and non-clinical isolates, a total of 22 genomes were studied by single nucleotide polymorphism (SNPs). The epidemiological analysis of 22 genomes of S. Typhimurium ST313 strains grouped them into three distinct clusters (A, B, and C) by SNP analysis, where cluster A comprised five, group B six, and group C 11. The 13 clinical blood isolates were all resistant to streptomycin, 92.3% of strains were resistant to ampicillin and 15.39% were resistant to kanamycin. The resistance genes acrA, acrB, mdtK, emrB, emrR, mdsA, and mdsB related to the production of efflux pumps were detected in all (100%) strains studied, similar to pathogenic traits investigated. In conclusion, we evidenced that S. Typhimurium ST313 strains isolated in Brazil have unique epidemiology. The elevated frequencies of virulence genes such as sseJ, sopD2, and pipB are a major concern in these Brazilian isolates, showing a higher pathogenic potential.

Transfer of T6SSSPI-19 from Salmonella Gallinarum to Salmonella Typhimurium Lacking T6SSSPI-6 Complements its Colonization Defect in Mice.

Salmonella genus harbors five Type VI Secretion System (T6SS) gene clusters. The T6SS encoded in SPI-6 (T6SSSPI-6) contributes to Salmonella Typhimurium colonization of chickens and mice, while the T6SS encoded in SPI-19 (T6SSSPI-19) of Salmonella Gallinarum contributes to chicken colonization. Interestingly, the T6SSSPI-19 of Salmonella Gallinarum complemented the defect in chicken colonization of a Salmonella Typhimurium strain that lacks the T6SSSPI-6, suggesting that both T6SSs are interchangeable. Here we show that the transfer of Salmonella Gallinarum T6SSSPI-19 complemented the defect in mice colonization of a Salmonella Typhimurium ΔT6SSSPI-6 strain, indicating that both T6SSs are functionally redundant during host colonization.

Class 1 integrons in clinical and swine industry isolates of Salmonella Typhimurium from Colombia, dating 1997 to 2017.

Background. Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) has been linked to outbreaks of foodborne gastroenteritis disease, and the emergence of antimicrobial-resistant clones. In Colombia, laboratory surveillance of Salmonella spp. between 1997-2018 revealed that S. Typhimurium was the most ubiquitous serovar (27.6 % of all Salmonella isolates), with increasing levels of resistance to several families of antibiotics.Hypothesis. Resistant isolates of S. Typhimurium recovered from human clinical, food and swine samples carry class 1 integrons that are linked to antimicrobial resistance genes.Aim. Identify class 1 integrons, and investigate their association with other mobile genetic elements, and their relationship to the antimicrobial resistance of Colombian S. Typhimurium isolates.Methods. In this study, 442 isolates of S. Typhimurium were analysed, of which 237 were obtained from blood culture, 151 from other clinical sources, 4 from non-clinical sources and 50 from swine samples. Class 1 integrons and plasmid incompatibility groups were analysed by PCR and whole-genome sequencing (WGS), and regions flanking integrons were identified by WGS. The phylogenetic relationship was established by multilocus sequence typing (MLST) and single-nucleotide polymorphism (SNP) distances for 30 clinical isolates.Results . Overall, 39 % (153/392) of the human clinical isolates and 22 % (11/50) of the swine S. Typhimurium isolates carried complete class 1 integrons. Twelve types of gene cassette arrays were identified, including dfr7-aac-bla OXA-2 (Int1-Col1), which was the most common one in human clinical isolates (75.2 %, 115/153). Human clinical and swine isolates that carried class 1 integrons were resistant to up to five and up to three antimicrobial families, respectively. The Int1-Col1 integron was most prevalent in stool isolates and was associated with Tn21. The most common plasmid incompatibility group was IncA/C.Conclusions. The widespread presence of the IntI1-Col1 integron in Colombia since 1997 was striking. A possible relationship between integrons, source and mobile elements that favour the spread of antimicrobial resistance determinants in Colombian S. Typhimurium was identified.

Neutral Electrolyzed Water in Chicken Breast-A Preservative Option in Poultry Industry.

Chicken is one of the most consumed meats in the world because it is an economical protein source with a low fat content. Its conservation is important to maintain safety along the cold chain. In the present study, the effect of Neutral Electrolyzed Water (NEW) at 55.73 ppm was evaluated on contaminated chicken meat with Salmonella Typhimurium and Escherichia coli O157:H7, which was stored in refrigerated conditions. The present study was carried out to check whether the application of NEW can help to preserve chicken breasts without affecting its sensory characteristics. Chicken quality was measured by analyzing physicochemical properties (pH, color, lactic acid, total volatile basic nitrogen, and thiobarbituric acid reactive substances content) after bactericidal intervention. This work includes a sensory study to determine if its use affects the organoleptic properties of the meat. The results showed that in the in vitro assay, NEW and NaClO, achieved bacterial count reductions of >6.27 and 5.14 Log10 CFU for E. coli and Salmonella Typhimurium, respectively, even though, in the in situ challenge, they showed a bacterial decrease of 1.2 and 0.33 Log10 CFU/chicken breast in contaminated chicken breasts with E. coli and Salmonella Typhimurium, respectively, after 8 days of storage, and NaClO treatment did not cause bacterial reduction. Nonetheless, NEW and NaClO did not cause lipid oxidation and nor did they affect lactic acid production, and they also slowed meat decomposition caused by biogenic amines. Sensory results showed that chicken breast characteristics like appearance, smell, and texture were not affected after NEW treatment, and obtained results showed that NEW could be used during chicken meat processing due to the chicken physicochemical stability. However, more studies are still needed.

hilD Is Required for the Active Internalization of Salmonella Newport into Cherry Tomatoes.

Salmonella enterica is a foodborne pathogen that can be internalized into fresh produce. Most of the Salmonella virulence genes are clustered in regions denominated Salmonella Pathogenicity Islands (SPI). SPI-1 encodes a Type Three Secretion System (T3SS-1) and effector proteins that allow the internalization of Salmonella into animal cells. HilD is a transcriptional regulator that induces the expression of SPI-1 genes and other related virulence genes located outside of this island. Here, we assessed the role of hilD in the internalization of Salmonella Newport and Typhimurium into cherry tomatoes, by evaluating either an isolate from an avocado orchard, S. Newport-45 or the laboratory strain S. Typhimurium SL1344 and their isogenic mutants in hilD. The internalization of these bacteria was carried out by using a temperature gradient of 12°C. The transcription of hilD and invA was tested by qRT-PCR experiments. Our results show that S. Newport-45 hilD mutant viable cells obtained from the interior of the fruit were decreased (2.7-fold), compared with those observed for S. Typhimurium SL1344. Interestingly, at 3 days postinoculation, the cells recovered from S. Newport-45 hilD mutant were similar to those recovered from all the strains evaluated, suggesting that hilD is required only for the initial internalization of S. Newport.

Evaluation of a Functional Craft Wheat Beer Fermented with Saccharomyces cerevisiae UFMG A-905 to treat Salmonella Typhimurium infection in mice.

Functional foods containing probiotics are generally administered as dairy products. Non-dairy beverages are another possibility, but probiotic functionality must be confirmed in such vehicles. In the present study, a craft wheat beer brewed with the probiotic yeast Saccharomyces cerevisiae UFMG A-905 (905) was evaluated in a murine model of Salmonella Typhimurium infection. Unfiltered or filtered beer brewed with 905, a commercial wheat beer used as a negative control, or saline were administered orally to mice before and during oral S. Typhimurium challenge. High fecal levels of yeast were only counted in mice treated with the unfiltered 905 beer, which also had reduced mortality and body weight loss due to S. Typhimurium infection. Increased levels of intestinal IgA, translocation to liver and spleen, liver and intestinal lesions, pro-inflammatory cytokines in liver and ileum, and hepatic and intestinal myeloperoxidase and eosinophilic peroxidase activities were observed in animals infected with S. Typhimurium. All these parameters were reduced by the treatment with unfiltered 905 beer. In conclusion, the results show that a craft wheat beer brewed with S. cerevisiae UFMG A-905 maintained the probiotic properties of this yeast when administered orally to mice challenged with S. Typhimurium.

Prevalence, serovars, and risk factors associated with the presence of Salmonella in pork sold in public markets in Quito, Ecuador.

Background: Salmonella enterica are bacteria that include more than 2,500 serovars. Most of these serovars have been linked to human foodborne illnesses, mainly related to poultry and pigs. Thus, these animals are considered the reservoirs of many Salmonella serovars and strains related to antibiotic resistance. This study aimed to determine the prevalence, serovars, ß-lactam resistance genes, and the risk factors associated with Salmonella enterica in pork commercialized in open markets of Quito city. Methods: For this, 165 pork meat samples were taken from municipal markets in three areas in the city. These samples were microbiologically processed following the ISO 6579-2014 standardized method. The polymerase chain reaction (PCR) test was used to identify Salmonella serotyping and resistance genes. Strains not identified by PCR were typed by the Kauffman White Le Minor scheme. A multivariate analysis was performed to identify risk factors associated with the presence of the microorganism. Results: Salmonella prevalence in pork was 9.1%. Identified serovars were 4, [5], 12: i:- (53.3%), Infantis (33.3%), and Derby (13.4%). Furthermore, the ß-lactam resistance genes bla CTX-M-65 could be identified in three S. infantis isolates. Multivariate analysis showed that temperature (above 8°C) and cutting surfaces (wood) presented significant association values. Conclusions: In conclusion, pork in traditional markets of Quito is contaminated with Salmonella enterica, whose main serovars pose a public health concern, and shows beta-lactam resistance.

Use of organic acids to reduce Salmonella Typhimurium excretion in swine / Uso de ácidos orgânicos para reduzir a excreção de Salmonella Typhimurium em suínos

The use of antimicrobials as growth promoters and disease prevention is being constantly reduced in several animal production systems, including in the swine industry. Therefore, this study aimed to evaluate the effectiveness of using acidifiers to control Salmonella Typhimurium in 65-day-old pigs by detecting the pathogen in organs at euthanasia. For this, 24 piglets were divided into two experimental groups consisting of 12 piglets each. An untreated control group (G1) and a treatment group (G2) received a liquid organic acidifier in the drinking water for 10 days (D-5 to D5). Five days after the start of treatment (D0), all piglets were challenged with 106 CFU of Salmonella Typhimurium and assessed for 12 days (D12). Every three days (D3, D6, D9, and D12), three animals from each experimental group were euthanized and then submitted for necropsy. Samples from the intestines (ileum, cecum, mesenteric lymph nodes, and ileocolic lymph nodes), liver, spleen, and lungs were collected to isolate Salmonella. The results show that, numerically, Salmonella isolation in the organs of G2 was lower than in G1 and that the number of positive cecum samples in G1 (66.7%; 8/12) was statistically different from the number of positive models in G2 (16.7%; 2/12), with a reduction of 28.6% of the total cecum positive samples in the treated group compared to the control. Therefore, it was observed that the liquid organic acidifier product could reduce the colonization of organs by Salmonella Typhimurium. (AU)