Enterica Typhimurium Research Articles

Antimicrobial effect of lactoferrin and glycerol monolaurate on selected bacteria associated with newborn infections

Human breast milk contains a rich array of bioactive substances, such as immunoglobulins, lactoferrin antimicrobial peptides, and glycerol monolaurate, which play a crucial role in providing immune protection to infants. Infant formula manufacturers strive to match mother's milk's nutritional makeup, including immune-boosting ingredients. Lactoferrin and glycerol monolaurate (GML) are important antibacterial compounds in human milk. The study aimed to investigate the effect of bovine lactoferrin (bLf) and GML in preventing the growth of inoculated bacteria into infant formula. The study examined both individual and combined use of these components. The bacteria that were tested included: 1) Gram-negative bacteria: Cronobacter sakazakii strains 12868 and 29004, Pseudomonas aeruginosa, Salmonella enterica Typhimurium, and 2) Gram-positive bacteria: Methicillin-resistant Staphylococcus aureus (MRSA), and Listeria monocytogenes. The result of the agar diffusion assays showed that bLf, at a concentration of 16 mg/disc, exhibited strong inhibition (≥20 mm) of all the selected bacterial strains. On the other hand, GML at a concentration of 8 mg/disc showed strong inhibition of all strains; however, Gram-positive bacteria were more susceptible, so a concentration of 5 mg/disc was enough to achieve strong inhibition of these strains. The minimal bactericidal concentrations (MBC) analysis aimed to achieve a >3-log reduction in the growth of various bacterial strains. The results showed that S. enterica Typhimurium and L. monocytogenes were more susceptible to bLf than the other strains (MBC: 7 and 4.8 mg/ml, respectively, vs. 14.9–18.4 mg/ml for the other strains). In contrast, MRSA and L. monocytogenes were more susceptible to GML (MBC: 6 and 10 mg/ml, respectively, vs. 16–18 mg/ml for Gram-negative strains). The results of reconstituted powdered infant formulas (RPIF), with the addition of bLf, GML, or both at pathogen-specific MBC, showed significant log reductions in the growth of experimentally inoculated bacteria compared to the control at different time intervals. All bacterial strains exposed to bLf and GML exhibited >3-log reduction within 72 h, with Gram-positive strains showing >7-log reduction. GML and bLf combined had a stronger anti-bacterial activity than individual components, indicating the potential of combining GML and bLf as natural agents against specific pathogenic bacteria. Future studies are needed to understand the potential use of these compounds in different food matrices and clinical settings.

The acquired pco gene cluster in Salmonella enterica mediates resistance to copper.

The pervasive environmental metal contamination has led to selection of heavy-metal resistance genes in bacteria. The pco and sil clusters are located on a mobile genetic element and linked to heavy-metal resistance. These clusters have been found in Salmonella enterica serovars isolated from human clinical cases and foods of animal origin. This may be due to the use of heavy metals, such as copper, in animal feed for their antimicrobial and growth promotion properties. The sil cluster can be found alone or in combination with pco cluster, either in the chromosome or on a plasmid. Previous reports have indicated that sil, but not pco, cluster contributes to copper resistance in S. enterica Typhimurium. However, the role of the pco cluster on the physiology of non-typhoidal S. enterica remains poorly understood. To understand the function of the pco gene cluster, a deletion mutant of pcoABCD genes was constructed using allelic exchange mutagenesis. Deletion of pcoABCD genes inhibited growth of S. enterica in high-copper medium, but only under anaerobic environment. Complementation of the mutant reversed the growth phenotype. The survival of S. enterica in RAW264.7 macrophages was not affected by the loss of pcoABCD genes. This study indicates that the acquired pco cluster is crucial for copper detoxification in S. enterica, but it is not essential for intracellular replication within macrophages.

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 6days 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.

Combined effect of SAR-endolysin LysKpV475 with polymyxin B and Salmonella bacteriophage phSE-5.

Endolysins are bacteriophage (or phage)-encoded enzymes that catalyse the peptidoglycan breakdown in the bacterial cell wall. The exogenous action of recombinant phage endolysins against Gram-positive organisms has been extensively studied. However, the outer membrane acts as a physical barrier when considering the use of recombinant endolysins to combat Gram-negative bacteria. This study aimed to evaluate the antimicrobial activity of the SAR-endolysin LysKpV475 against Gram-negative bacteria as single or combined therapies, using an outer membrane permeabilizer (polymyxin B) and a phage, free or immobilized in a pullulan matrix. In the first step, the endolysin LysKpV475 in solution, alone and combined with polymyxin B, was tested in vitro and in vivo against ten Gram-negative bacteria, including highly virulent strains and multidrug-resistant isolates. In the second step, the lyophilized LysKpV475 endolysin was combined with the phage phSE-5 and investigated, free or immobilized in a pullulan matrix, against Salmonella enterica subsp. enterica serovar Typhimurium ATCC 13311. The bacteriostatic action of purified LysKpV475 varied between 8.125 μg ml-1 against Pseudomonas aeruginosa ATCC 27853, 16.25 μg ml-1 against S. enterica Typhimurium ATCC 13311, and 32.50 μg ml-1 against Klebsiella pneumoniae ATCC BAA-2146 and Enterobacter cloacae P2224. LysKpV475 showed bactericidal activity only for P. aeruginosa ATCC 27853 (32.50 μg ml-1) and P. aeruginosa P2307 (65.00 μg ml-1) at the tested concentrations. The effect of the LysKpV475 combined with polymyxin B increased against K. pneumoniae ATCC BAA-2146 [fractional inhibitory concentration index (FICI) 0.34; a value lower than 1.0 indicates an additive/combined effect] and S. enterica Typhimurium ATCC 13311 (FICI 0.93). A synergistic effect against S. enterica Typhimurium was also observed when the lyophilized LysKpV475 at ⅔ MIC was combined with the phage phSE-5 (m.o.i. of 100). The lyophilized LysKpV475 immobilized in a pullulan matrix maintained a significant Salmonella reduction of 2 logs after 6 h of treatment. These results demonstrate the potential of SAR-endolysins, alone or in combination with other treatments, in the free form or immobilized in solid matrices, which paves the way for their application in different areas, such as in biocontrol at the food processing stage, biosanitation of food contact surfaces and biopreservation of processed food in active food packing.

Simulated microgravity facilitates stomatal ingression by Salmonella in lettuce and suppresses a biocontrol agent

As human spaceflight increases in duration, cultivation of crops in spaceflight is crucial to protecting human health under microgravity and elevated oxidative stress. Foodborne pathogens (e.g., Salmonella enterica) carried by leafy green vegetables are a significant cause of human disease. Our previous work showed that Salmonella enterica serovar Typhimurium suppresses defensive closure of foliar stomata in lettuce (Lactuca sativa L.) to ingress interior tissues of leaves. While there are no reported occurrences of foodborne disease in spaceflight to date, known foodborne pathogens persist aboard the International Space Station and space-grown lettuce has been colonized by a diverse microbiome including bacterial genera known to contain human pathogens. Interactions between leafy green vegetables and human bacterial pathogens under microgravity conditions present in spaceflight are unknown. Additionally, stomatal dynamics under microgravity conditions need further elucidation. Here, we employ a slow-rotating 2-D clinostat to simulate microgravity upon in-vitro lettuce plants following a foliar inoculation with S. enterica Typhimurium and use confocal microscopy to measure stomatal width in fixed leaf tissue. Our results reveal significant differences in average stomatal aperture width between an unrotated vertical control, plants rotated at 2 revolutions per minute (2 RPM), and 4 RPM, with and without the presence of S. typhimurium. Interestingly, we found stomatal aperture width in the presence of S. typhimurium to be increased under rotation as compared to unrotated inoculated plants. Using confocal Z-stacking, we observed greater average depth of stomatal ingression by S. typhimurium in lettuce under rotation at 4 RPM compared to unrotated and inoculated plants, along with greater in planta populations of S. typhimurium in lettuce rotated at 4 RPM using serial dilution plating of homogenized surface sterilized leaves. Given these findings, we tested the ability of the plant growth-promoting rhizobacteria (PGPR) Bacillus subtilis strain UD1022 to transiently restrict stomatal apertures of lettuce both alone and co-inoculated with S. typhimurium under rotated and unrotated conditions as a means of potentially reducing stomatal ingression by S. typhimurium under simulated microgravity. Surprisingly, rotation at 4 RPM strongly inhibited the ability of UD1022 alone to restrict stomatal apertures and attenuated its efficacy as a biocontrol following co-inoculation with S. typhimurium. Our results highlight potential spaceflight food safety issues unique to production of crops in microgravity conditions and suggest microgravity may dramatically reduce the ability of PGPRs to restrict stomatal apertures.

Comparison of Antibacterial Activity of Phytochemicals against Common Foodborne Pathogens and Potential for Selection of Resistance.

Antimicrobial resistance is now commonly observed in bacterial isolates from multiple settings, compromising the efficacy of current antimicrobial agents. Therefore, there is an urgent requirement for efficacious novel antimicrobials to be used as therapeutics, prophylactically or as preservatives. One promising source of novel antimicrobial chemicals is phytochemicals, which are secondary metabolites produced by plants for numerous purposes, including antimicrobial defence. In this report, we compare the bioactivity of a range of phytochemical compounds, testing their ability to directly inhibit growth or to potentiate other antimicrobials against Salmonella enterica Typhimurium, Pseudomonas aeruginosa, Listeria monocytogenes, and Staphylococcus aureus. We found that nine compounds displayed consistent bioactivity either as direct antimicrobials or as potentiators. Thymol at 0.5 mg/mL showed the greatest antimicrobial effect and significantly reduced the growth of all species, reducing viable cell populations by 66.8%, 43.2%, 29.5%, and 70.2% against S. enterica Typhimurium, S. aureus, P. aeruginosa, and L. monocytogenes, respectively. Selection of mutants with decreased susceptibility to thymol was possible for three of the pathogens, at a calculated rate of 3.77 × 10-8, and characterisation of S. enterica Typhimurium mutants showed a low-level MDR phenotype due to over-expression of the major efflux system AcrAB-TolC. These data show that phytochemicals can have strong antimicrobial activity, but emergence of resistance should be evaluated in any further development.

Intrinsic insights to antimicrobial effects of Nitrofurantoin to multi drug resistant Salmonella enterica serovar Typhimurium ms202

Emerging multidrug resistant (MDR) serovar of Salmonella has raised the concern of their impactful effect on pathogenic infection and mortality in human lead by the enteric diseases. In order to combat the battle against these MDR Salmonella pathogen, new drug molecules need to be evaluated for their potent antibacterial application. This study evaluates the mechanistic antimicrobial effect of nitrofurantoin against a MDR strain of Salmonella named S. enterica Typhimurium ms202. The antimicrobial effect of nitrofurantoin was studied through experimental and computational approach using standard microbiological and molecular techniques like growth curve analysis, live-dead analysis, oxidative stress evaluation using high throughput techniques like flow cytometry and fluorescent microscopy. The result showed a potent dose dependent antibacterial effect of nitrofurantoin against S. enterica Typhimurium ms202 with a MIC value of 64 µg/ml. Moreover, the mechanistic excavation of the phenomenon described the mechanism as an effect of molecular interaction of nitrofurantoin molecule with membrane receptor proteins OmpC of S. enterica Typhimurium ms202 leading to internalization of the nitrofurantoin heading towards the occurrence of cellular physiological disturbances through oxidative stress impeded by nitrofurantoin-Sod1 C protein interaction. The results indicated towards a synergistic effect of membrane damage, oxidative stress and genotoxicity for the antibacterial effect of nitrofurantoin against S. enterica Typhimurium ms202. The study described the potent dose-dependent application of nitrofurantoin molecule against MDR strains of Salmonella and guided towards their use in further discovered MDR strains.

Antibacterial effect of rose bengal against colistin-resistant gram-negative bacteria.

Increasing drug resistance in Gram-negative bacteria presents significant health problems worldwide. Despite notable advances in the development of a new generation of β-lactams, aminoglycosides, and fluoroquinolones, it remains challenging to treat multi-drug resistant Gram-negative bacterial infections. Colistin (polymyxin E) is one of the most efficacious antibiotics for the treatment of multiple drug-resistant Gram-negative bacteria and has been used clinically as a last-resort option. However, the rapid spread of the transferable gene, mcr-1 which confers colistin resistance by encoding a phosphoethanolamine transferase that modifies lipid A of the bacterial membrane, threatens the efficacy of colistin for the treatment of drug-resistant bacterial infections. Colistin-resistant strains of Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae often reduce their susceptibility to other anti-Gram-negative bacterial agents. Thus, drugs effective against colistin-resistant strains or methods to prevent the acquisition of colistin-resistance during treatment are urgently needed. To perform cell-based screenings of the collected small molecules, we have generated colistin-resistant strains of E. coli, A. baumannii, K. pneumoniae, P. aeruginosa, and S. enterica Typhimurium. In-house MIC assay screenings, we have identified that rose bengal (4,5,6,7-tetrachloro-2',4',5',7'-tetraiodofluorescein) is the only molecule that displays unique bactericidal activity against these strains at low concentrations under illumination conditions. This article reports the antibacterial activity of a pharmaceutical-grade rose bengal against colistin-resistant Gram-negative bacteria.

Green Synthesis of Na abietate Obtained from the Salification of Pinus elliottii Resin with Promising Antimicrobial Action.

The growing concern about the emergence of increasingly antibiotic-r4esistant bacteria imposes the need to search and develop drugs to combat these microorganisms. This, combined with the search for low-cost synthesis methods, was the motivation for the elaboration of this work. Abietic acid present in the resin of Pinus elliotti var. elliotti was used to generate a sodium salt by salification. The synthesis route was low-cost, consisting of only two reaction steps at mild temperatures without toxic organic solvents, and eco-friendly and easy to conduct on an industrial scale. Sodium abietate (Na-C20H29O2) was characterized by mass spectrometry, infrared spectroscopy, elemental analysis, X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. To perform the antimicrobial tests, the determination of minimum inhibitory concentration and the disk diffusion assay was performed. The results obtained showed that the salt Na abietate performed an antimicrobial action against the bacterial strains S. aureus, E. coli, L.monocytogenes, and S. enterica Typhimurium and the yeast C. albicans. The disk diffusion test showed a high inhibition potential against S. enterica compared to the standard antimicrobial tetracycline, as an inhibition index of 1.17 was found. For the other bacterial strains, the inhibition values were above 40%. The MIC test showed promising results in the inhibition of E. coli, L. monocytogenes, and C. albicans, indicating bacteriostatic activity against the first microorganism and bactericidal and fungicidal activities against the others. Therefore, the results showed the action of Na abietate as a possible effective antimicrobial drug, highlighting its sustainability within a circular economy.

Draft genome of clinical isolate Salmonella enterica Typhimurium ms204 from Odisha, India, reveals multi drug resistance and decreased virulent gene expression

Salmonellosis, a food-borne illnesses caused by enteropathogenic bacterium Salmonella spp., is a continuous concern in both developed and developing countries. This study was carried out to perform an in-depth examination of an MDR Salmonella strain isolated from gastroenteritis patients in Odisha, India, in order to understand the genomic architecture, distribution of pathogenic island regions, and virulence factor diversity. Fecal samples were obtained from individuals with acute gastroenteritis and further subjected to panel of biochemical tests. The IlluminaHiSeq X sequencer system was used to generate whole-genome sequencing. The draft genome was submitted to gene prediction and annotation using RAST annotation system. Pathogenicity Island database and bioinformatics pipeline were used to find Salmonella pathogenicity islands (SPI) from the built scaffold. The gene expression in SPI1 and SPI2 encoded regions was investigated using qRT-PCR. The taxonomic position of Salmonella enterica subsp. enterica serovar Typhimurium was validated by serotype analysis and 16S rRNA based phylogenetic analysis. The de-novo genome assembly showed total length of 5,034,110 bp and produced 37 contigs. There are nine prophage areas, comprising of 12 regions and scaffold 8 contained a single plasmid, IncFIB. The isolate contains six known SPI genes content which was shown to be largely conserved from SPI1 to SPI2. We identified the sit ABCD cluster regulatory cascade and acquired antibiotic resistance genes in S. enterica Typhimurium ms204. Further research may aid in the correct diagnosis and monitoring of MDR Salmonella strains with a variety of physiological activities.

Extraction and characterization of phenolic compounds with antioxidant and antimicrobial activity from avocado seed (Persea americana mill)

The increase in the demand for Hass avocado has brought a rise in the generation of inedible waste such as peel and seed, by-products that are rich in bioactive substances. In the present study, aqueous, ethanolic, and supercritical fluid extracts were obtained from fresh seed and dry seed, which were analyzed to determine the antioxidant capacity measured through 2,2-diphenyl-2-picrylhydrazyl free radical (DPPH); 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) methods as well as the content of phenolic compounds. In addition, the antimicrobial activity of strains of food interest, such as Listeria monocytogenes, Salmonella enterica Typhimurium and Escherichia coli was evaluated. The ethanolic extract of fresh seed presented the highest antioxidant and antimicrobial activity. The aqueous extract of fresh seed registered a significant antioxidant capacity but an absence of antimicrobial activity. In contrast, the ethanolic extract of dry seed showed a representative antimicrobial activity on both S. enterica Typhimurium and L. monocytogenes, but low antioxidant activity. E. coli exhibited resistance against all the assessed extracts. The results from this work highlight the opportunity to consider the Hass avocado seed extracts as a novel alternative to replace or reduce the use of synthetic antioxidant and antimicrobial additives in food. Keywords: Waste by-product; Aqueous extract; Ethanolic extract; Supercritical extraction; Polyphenols; Free radical.

P53 gene delivery via a recombinant Salmonella enterica Typhimurium leads to human bladder carcinoma cell death invitro.

Numerous studies have attempted to restore the function of the tumour suppressor p53 as an anti-cancer strategy through gene delivery. However, most studies employed non-bacterial vectors to deliver p53. Various facultative and obligate anaerobic bacteria have been proposed as vectors because of their intrinsic tumour targeting ability and anti-tumour activity. Salmonella enterica Typhimurium is the most studied bacterial vector in anti-cancer therapy. We used the previously designed χ11218 strain of S. enterica Typhimurium, displaying regulated delayed lysis, as a vector for delivering p53 to human bladder carcinoma cells, restoring wild-type p53 protein function. We cloned p53 into pYA4545 (containing a eukaryotic expression system) to generate the χ11218 pYA4545p53 strain. Cloning of p53 did not affect the growth or interfere with the invasive and replicative capacity of χ11218 bacteria in tumour cells. Human bladder carcinoma cells (expressing mutated p53) transfected with pYA4545p53 showed a significant increase in the expression of p53 protein. We demonstrated that p53 supplied by χ11218 significantly decreased the viability of human bladder cancer cells in a dose-dependent manner. This study demonstrates the applicability of the attenuated χ11218 strain as a vector for DNA plasmids expressing tumour suppressor genes.

Salmonella Exhibit Altered Cellular Localization in the Presence of HLA-B27 and Codistribute with Endo-Reticular Membrane.

Salmonella enteritica (S. enteritica) induce and require unfolded protein response (UPR) pathways for intracellular replication. Salmonella infections can lead to reactive arthritis (ReA), which can exhibit associations with Human Leucocyte Antigen (HLA)-B∗27 : 05. S. enteritica normally reside in a juxtanuclear position to the Golgi apparatus, representing the formation and residence within the Salmonella-containing vacuole (SCV). Changes in cellular localization of infecting Salmonella can alter their ability to replicate. We therefore used isogenic epithelial cell lines expressing physiological levels of HLA-B∗27 : 05 heavy chain (HC) and a control HLA-B allele, HLA-B∗35 : 01.HC to determine any changes in Salmonella localization within epithelial cells. Expression of HLA-B∗27 : 05 but not HLA-B∗35 : 01 was associated with a quantifiable change in S. enteritica cellular distribution away from the Golgi apparatus. Furthermore, the Salmonella requirements for UPR induction and the consequences of the concomitant endoplasmic reticulum (ER) membrane expansion were determined. Using confocal imaging, S. enteritica bacteria exhibited a significant and quantifiable codistribution with endo-reticular membrane as determined by ER tracker staining. Isogenic S. enterica Typhimurium mutant strains, which can infect but exhibit impaired intracellular growth, demonstrated that the activation of the UPR was dependent on an integral intracellular niche. Therefore, these data identify cellular changes accompanying Salmonella induction of the UPR and in the presence of HLA-B27.

In-Depth Study of Thymus vulgaris Essential Oil: Towards Understanding the Antibacterial Target Mechanism and Toxicological and Pharmacological Aspects.

Questions have been raised apropos the emerging problem of microbial resistance, which may pose a great hazard to the human health. Among biosafe compounds are essential oils which captured consumer draw due to their multifunctional properties compared to chemical medication drugs. Here, we examined the chemical profile and the mechanism(s) of action of the Thymus vulgaris essential oil (TVEO) against a Gram-negative bacterium Salmonella enterica Typhimurium ATTCC 10028 (S. enterica Typhimurium ATTCC 10028) and two Gram-positive bacteria Staphyloccocus aureus ATCC 6538 (S. aureus ATCC 6538) and Listeria monocytogenes ATCC 19117 (L. monocytogenes ATCC 19117). Findings showed that TVEO was principally composed of thymol, o-cymene, and γ-terpinene with 47.44, 16.55, and 7.80%, respectively. Molecular docking simulations stipulated that thymol and β-sesquiphellandrene (a minor compound at 1.37%) could target multiple bacterial pathways including topoisomerase II and DNA and RNA polymerases of the three tested bacteria. This result pointed plausible impairments of the pathogenic bacteria cell replication and transcription processes. Through computational approach, the VEGA quantitative structure–activity relationship (QSAR) model, we revealed that among twenty-six TVEO compounds, sixteen had no toxic effects and could be safe for human consumption as compared to the Food and Drug Administration (FDA) approved drugs (ciprofloxacin and rifamycin SV). Assessed by the SwissADME server, the pharmacokinetic profile of all identified TVEO compounds define their absorption, distribution, metabolism, and excretion (ADME) properties and were assessed. In order to predict their biological activity spectrum based on their chemical structure, all TVEO compounds were subjected to PASS (Prediction of Activity Spectra for Substances) online tool. Results indicated that the tested compounds could have multiple biological activities and various enzymatic targets. Findings of our study support that identified compounds of TVEO can be a safe and effective alternative to synthetic drugs and can easily combats hazardous multidrug-resistant bacteria.

Genome analysis and virulence gene expression profile of a multi drug resistant Salmonella enterica serovar Typhimurium ms202

BackgroundIn India, multi-drug resistance in Salmonella enterica serovar Typhimurium poses a significant health threat. Indeed, S. Typhimurium has remained unknown for a large portion of its genome associated with various physiological functions including mechanism of drug resistance and virulence. The whole-genome sequence of a Salmonella strain obtained from feces of a patient with gastroenteritis in Odisha, India, was analyzed for understanding the disease association and underlying virulence mechanisms.ResultsThe de novo assembly yielded 17 contigs and showed 99.9% similarity to S. enterica sub sp enterica strain LT2 and S. enteric subsp salamae strain DSM 9220. S. Typhimurium ms202 strain constitutes six known Salmonella pathogenicity islands and nine different phages. The comparative interpretation of pathogenic islands displayed the genes contained in SPI-1 and SPI-2 to be highly conserved. We identified sit ABCD cluster regulatory cascade in SPI-1. Multiple antimicrobial resistance genes were identified that directly implies antibiotic-resistant phenotype. Notably, seven unique genes were identified as "acquired antibiotic resistance". These data suggest that virulence in S. enterica Typhimurium ms202 is associated with SPI-1 and SPI-2. Further, we found several virulent genes encoding SPI regions belonging to type III secretion systems (T3SS) of bacteria were significantly upregulated in ms202 compared to control LT2. Moreover, all these genes were significantly downregulated in S. enterica Typhimurium ms202 as compared to control LT2 on adding Mn2+ exogenously.ConclusionsOur study raises a vital concern about the potential diffusion of a novel multi-drug resistant S. enterica Typhimurium ms202. It justifies this clinical pathogen to demonstrate a higher degree survival due to higher expression of virulent genes and enhanced ability of metallic ion acquisition.

Green synthesis, and characterization of zinc oxide nanoparticles using Piper longum catkin extract and its in vitro antimicrobial activity against multi-drug-resistant non-typhoidal Salmonella spp.

This study attempted synthesis and characterization of zinc oxide nanoparticles (ZnO NPs) using the aqueous extract of Piper longum catkin and its in vitro antibacterial efficacy against multi-drug-resistant strains (MDR) of non- typhoidal Salmonella (NTS) spp. (S. enterica Typhimurium and S. Enteritidis). The green synthesized ZnO NPs exhibited an absorbance peak at 340 nm by UV-Vis spectroscopy, which was confirmed by FTIR analysis. The TGA/DTA revealed a progressive thermal degradation of the ZnO NPs between 250 °C and 400 °C; however, good thermal stability was exhibited for annealing temperatures between 900 °C and 1300 °C. The ZnO NPs exhibited hexagonal wurtzite crystalline structure by PXRD analysis, which was further confirmed by electron microscopy. Microbroth dilution technique exhibited an MIC and MBC values of 125 and 250 µg/mL, respectively. Overall, the study demonstrated a facile, eco-friendly method for the synthesis of ZnO NPs, which could be employed as a potential antimicrobial alternative candidate.

Effective pulsed light treatments for inactivating Salmonella enterica serotypes

Pulsed light (PL) is a nonthermal treatment that kills microorganisms by exposing them to short-duration pulses of high-intensity broad-spectrum light. This study evaluated the PL inactivation of different serotypes of Salmonella enterica subsp. enterica (Typhimurium, Enteritidis, Heidelberg, and Minnesota) to specifically assess how pulse width and voltage can affect treatment effectiveness. Bacterial suspensions were spread onto solid agar plates, used as a model food surface, and then treated with PL at different treatment parameters (voltage, pulse width, and fluence). Surviving cells were recovered, enumerated, and the proportion of surviving cells were determined. The log-linear model was used to characterize inactivation kinetics. Three independent replicates were performed for all treatments, and data were analyzed statistically. The results obtained with S. Typhimurium highlighted that the inactivation effectiveness of PL treatment could be enhanced by selecting the right combination of parameters within the practical limitations of the equipment. Higher voltages delivered more energy with pulse width, (i.e., a higher irradiance) resulting in a more lethal process. PL was very effective for the inactivation of Salmonella, and a 6 to 7 log reduction was achieved for all four serotypes and their cocktail, after a single light pulse with a fluence of 338 mJ/cm2 and 280 mJ/cm2, at 2500 V (200 μs) and 3000 V (100 μs), respectively. The results demonstrated similar log reductions for individual serotypes and the cocktail.

Risk factors associated with Salmonella prevalence, its antibiotic resistance, and egg antibiotic residues in the layer farming environment

Background and Aim:Human salmonellosis with non-typhoidal Salmonella remains a global public health concern related to the consumption of contaminated eggs and egg-based products. This study aimed to examine the prevalence of Salmonella, antimicrobial-resistant Salmonella, and egg antibiotic residues concerning risk factors associated with Salmonella contamination in eggs, the layer farming environment, and laying hens kept in battery-cage closed-housing systems.Materials and Methods:This study used a repeated cross-sectional design to collect 488 samples from eggs, laying hens, and the farm environment on one laying farm for Salmonella detection according to ISO 6579:2002/AMD 1:2007. Salmonella-positive samples were further tested for serotype and antimicrobial susceptibility using the disk diffusion test. The layer farm contact person was interviewed at the sampling time to evaluate the risk factors associated with Salmonella contamination using logistic regression analysis. For each month, 24 eggs (144 eggs in total) were also randomly sampled from the collection egg area at the farm for antibiotic residue detection using the European Four Plate Test.Results:The highest Salmonella prevalence rates were in the samples from the layer pen floors, followed by the egg sizing machine (ESM) and eggshells at 65.5%, 52.5%, and 15%, respectively. Salmonella enterica serovar Corvallis was the dominant serovar (48.38%), followed by Mbandaka (37.76%), Braenderup (14.29%), and Typhimurium (4.08%). Rodent presence at the farm and the frequency of changing the disinfectant foot dip were significant factors related to Salmonella contamination on the pen floors (odds ratio [OR]=22.5, 95% confidence interval [CI]=2.11-240.48, p=0.01; OR=24, 95% CI=2.78-206.96, p=0.004, respectively). Hand-washing before sorting and cleaning the ESM were the significant factors (OR=13, 95% CI=1.2-140.73, p=0.04). The most resistant Salmonella isolates were resistant to oxytetracycline. One isolate of S. enterica Typhimurium was resistant to cefotaxime, enrofloxacin, and oxytetracycline. The antibiotic residues in the egg yolks were streptomycin, enrofloxacin, and tetracycline at prevalence rates of 36.11%, 11.81%, and 7.64%, respectively. Streptomycin was the most abundant residue in the albumen and yolk, followed by tetracycline.Conclusion:Salmonella prevalence in layer farming with a closed-housing system is related to effective biosecurity and hygiene issues, such as rodent control, clean farm equipment, and good worker hygiene. In addition, eggs’ antibiotic residues may be related to treating antimicrobial-resistant Salmonella isolates and medicated feed with inappropriate antibiotic withdrawal time.

Biochemical Profile and Antimicrobial Activity of an Herbal-Based Formula and Its Potential Application in Cosmetic Industry

Microbial infections, and especially microbial resistance, are critical and actual problems that require targeted and efficient therapeutic intervention. Natural-based solutions are a viable alternative, at least for complementary therapy, due to few or no side effects and high safety and efficacy levels. The aim of this study was to demonstrate the potential use of a patented formula based on Achillea millefolium, Origanum vulgare, and Lychnis coronaria species as an antibacterial ingredient, mainly for skin and mucosal infections, in order to support its pharmaco-cosmetic application. The chemical composition of the formula was analyzed by HPLC and spectrophotometric methods. Furthermore, antioxidant and antimicrobial activity were evaluated. To determine the formula’s safety for topical application, it was used on a reconstructed human epidermal model. The formula showed inhibitory activity on both Gram-positive and Gram-negative bacteria, respectively, moderate inhibition on B. cereus, Kocuria kristinae, P. aeurginosa, S. enterica Typhimurium, methicillin-resistant and methicillin-sensible S. aureus, as well as high inhibition on S. epidermidis, Serratia marescens, and Streptococcus pyogenes. The developed product was biochemically characterized for its content in polyphenols, triterpenes, and polyphenol carboxylic acids. The formula was proven to have a nonirritant effect on the human epidermis and important antioxidant activity.

Lacticaseicin 30 and Colistin as a Promising Antibiotic Formulation against Gram-Negative β-Lactamase-Producing Strains and Colistin-Resistant Strains.

Antimicrobial resistance is a global health concern across the world and it is foreseen to swell if no actions are taken now. To help curbing this well announced crisis different strategies are announced, and these include the use of antimicrobial peptides (AMP), which are remarkable molecules known for their killing activities towards pathogenic bacteria. Bacteriocins are ribosomally synthesized AMP produced by almost all prokaryotic lineages. Bacteriocins, unlike antibiotics, offer a set of advantages in terms of cytotoxicity towards eukaryotic cells, their mode of action, cross-resistance and impact of microbiota content. Most known bacteriocins are produced by Gram-positive bacteria, and specifically by lactic acid bacteria (LAB). LAB-bacteriocins were steadily reported and characterized for their activity against genetically related Gram-positive bacteria, and seldom against Gram-negative bacteria. The aim of this study is to show that lacticaseicin 30, which is one of the bacteriocins produced by Lacticaseibacillus paracasei CNCM I-5369, is active against Gram-negative clinical strains (Salmonella enterica Enteritidis H10, S. enterica Typhimurium H97, Enterobacter cloacae H51, Escherichia coli H45, E. coli H51, E. coli H66, Klebsiella oxytoca H40, K. pneumoniae H71, K. variicola H77, K. pneumoniae H79, K. pneumoniae H79), whereas antibiotics failed. In addition, lacticaseicin 30 and colistin enabled synergistic interactions towards the aforementioned target Gram-negative clinical strains. Further, the combinations of lacticaseicin 30 and colistin prompted a drastic downregulation of mcr-1 and mcr-9 genes, which are associated with the colistin resistance phenotypes of these clinical strains. This report shows that lacticaseicin 30 is active against Gram-negative clinical strains carrying a rainbow of mcr genes, and the combination of these antimicrobials constitutes a promising therapeutic option that needs to be further exploited.