Search Results (241)

Rapid screening of foodborne pathogens is critical for food safety, yet current detection techniques often suffer from low efficiency and complexity. In this study, we developed a sliding microfluidic colorimetric biosensor for the fast, sensitive, and multiplex detection of Salmonella. First, the target bacteria were specifically captured by antibody-functionalized magnetic nanoparticles in the microfluidic chip, forming magnetic bead–bacteria complexes. Then, through motor-assisted sliding of the chip, manganese dioxide (MnO₂) nanoflowers conjugated with secondary antibodies were introduced to bind the captured bacteria, generating a dual-antibody sandwich structure. Finally, a second sliding step brought the complexes into contact with a chromogenic substrate, where the MnO₂ nanoflowers catalyzed a colorimetric reaction, and the resulting signal was used to quantify the Salmonella concentration. Under optimized conditions, the biosensor achieved a detection limit of 10 CFU/mL within 20 min. In spiked pork samples, the average recovery rate of Salmonella ranged from 94.9% to 125.4%, with a coefficient of variation between 4.0% and 6.8%. By integrating mixing, separation, washing, catalysis, and detection into a single chip, this microfluidic biosensor offers a user-friendly, time-efficient, and highly sensitive platform, showing great potential for the on-site detection of foodborne pathogens. Full article

Background: Salmonella enterica and Escherichia coli are common foodborne pathogens of global concern, particularly due to their antimicrobial resistance, notably to cephalosporins. Objective: This study aimed to evaluate a polymerase chain reaction-based lateral flow strip (PCR-LFS) assay for the detection of Salmonella spp. and E. coli harboring the bla_CTX-M gene, which confers resistance to third-generation cephalosporins. Methods: Two duplex PCRs (dPCR) were established to detect E. coli-harboring bla_CTX-M (set 1) and Salmonella-harboring bla_CTX-M (set 2). 600 bacterial isolates and raw pork mince spiked with bla_CTX-M-harboring E. coli and Salmonella were used to evaluated. Results: Both dPCR assays successfully detected bla_CTX-M-positive E. coli or Salmonella strains, while strains lacking the gene showed no amplification. Non-E. coli and non-Salmonella strains were PCR-negative unless they carried bla_CTX-M. The dPCR-LFS showed 100% validity including accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for both E. coli or Salmonella spp. harboring or lacking bla_CTX-M. The assay accurately detected target strains without cross-reactivity with other bacteria or antimicrobial resistance genes. Cohen’s Kappa coefficient indicated perfect agreement (κ = 1), reflecting the high reliability of the dPCR-LFS. The assay could detect as low as 25 CFU/mL for bla_CTX-M-positive E. coli and 40 CFU/mL for bla_CTX-M-positive Salmonella in spiked raw pork mince. Conclusions: This assay is rapid, easy to interpret, and suitable for large-scale screening in surveillance programs. Full article

Background/Objectives: As bacteriophage-based strategies to control bacterial pathogens continue to gain momentum, phage therapy is increasingly being explored across various fields. In the poultry industry, efforts to minimize the public health impact of Salmonella have spurred growing interest in phage applications, particularly as prophylactic and disinfecting agents. Although the disinfecting potential of bacteriophages has been recognized, in-depth studies examining their efficacy under varying environmental conditions remain limited. This study focused on evaluating the effectiveness of bacteriophages as disinfecting agents against biofilm-forming Salmonella Infantis under different environments. Methods: A comprehensive screening of biofilm-producing strains was conducted using Congo Red Agar and 96-well plate assays. Two strains with distinct biofilm-forming capacities were selected for further analysis under different environmental conditions: aerobic and microaerobic atmospheres at both 25 °C and 37 °C. The resulting biofilms were then treated with four phage preparations: three individual phages and one phage cocktail. Biofilm reduction was assessed by measuring optical density and CFU/well. Additionally, scanning electron microscopy was used to visualize both untreated and phage-treated biofilms. Results: The results demonstrated that all S. Infantis strains were capable of forming biofilms (21/21). All three phage candidates exhibited biofilm-disrupting activity and were able to lyse biofilm-embedded Salmonella cells. Notably, the lytic efficacy of the phages varied depending on environmental conditions, highlighting the importance of thorough phage characterization prior to application. Conclusions: These findings underscore that the effectiveness of bacteriophages as surface disinfectants can be significantly compromised if inappropriate phages are used, especially in the presence of biofilms. Full article

Background: Salmonella infections impose a substantial global health burden, with an estimated 95.1 million cases occurring annually. Pregnant women exhibit a heightened vulnerability due to pregnancy-specific immune adaptations and dietary habits that increase their risk of Salmonella exposure, facilitating possible damage to the placental barrier. Despite this significant burden, Salmonella-associated placental pathology remains poorly understood, particularly its impact on foetal development through microstructural alterations. Aim: This study utilised stereology to assess histomorphological and functional alterations in term placentae of Salmonella Typhi-exposed placentae, compared to unexposed controls. Methods: A hospital-based case-control study was conducted in Ghana. Of 237 screened women, 62 placentae were selected for analysis, comprising 31 Salmonella-exposed cases (IgG/IgM-positive in placental and cord blood) and 31 gestational age-matched controls (IgG/IgM-negative). Placental tissues were processed for histology and stereology. Neonatal birthweights were also compared. Results: Stereological assessment revealed significantly higher mean volume densities of syncytial knots in the study group (0.4755 ± 0.04) compared to the controls (0.3342 ± 0.04, p = 0.0219). Syncytial denudation was increased in the study group (0.8113 ± 0.09) relative to the controls (0.1975 ± 0.08, p < 0.0001). Foetal capillary volume density was also significantly elevated in the study group (5.1010 ± 0.32) compared to the controls (3.562 ± 0.47, p < 0.0001). In contrast, intervillous space volume was significantly reduced in the study group (9.5810 ± 0.05) compared to the controls (11.593 ± 0.26, p = 0.0053). Neonates of exposed mothers showed a non-significant reduction in birthweight. Conclusion: Salmonella Typhi exposure in pregnancy induces subtle, yet significant alterations in placental architecture, compromising villous integrity and vascular organisation. Although birthweight may appear unaffected, the observed changes point to reduced placental efficiency and merit further research into their developmental consequences and long-term effects on babies. Full article

It is well established that flagella play a critical role in bacterial motility and virulence, and the genes associated with flagellar synthesis and regulation have been extensively characterized. In this study, we identified the trmE gene as a novel modulator of flagellar synthesis in Salmonella Enteritidis. A transposon (Tn5) mutant library of Salmonella Enteritidis (SE) was constructed through bacterial conjugation, followed by screening for motility-deficient mutants. Among 1321 mutants screened, C50041trmE::Tn5 exhibited reduced motility. To validate this phenotype, we constructed C50041ΔtrmE mutants and complementary strains C50041ΔtrmE::trmE. Compared to parental strain SE(C50041), C50041ΔtrmE displayed significantly lower mRNA levels of flagellar synthesis-related genes as determined via quantitative real-time PCR and the few visible flagella observed via transmission electron microscopy (TEM). Function studies assessing virulence also showed results that matched this phenotype; specifically, C50041ΔtrmE demonstrated decreased adhesion and invasion capabilities towards macrophages. Furthermore, C50041ΔtrmE induced impaired apoptosis and pyroptosis in macrophages, while exhibiting reduced mortality in BALB/c mice along with diminished mRNA levels of pro-inflammatory cellular factors within murine spleen. This study provides compelling evidence that the trmE gene in Salmonella Enteritidis is involved in flagellar synthesis. Full article

Antimicrobial resistance (AMR) is a major global concern in both human and veterinary medicine. Among antimicrobial resistance (AMR) bacteria, Extended-Spectrum Beta-Lactamases (ESBLs) pose a serious health risk because infections can be difficult to treat. These Gram-negative bacteria can be frequently found in poultry and in Italy, where such protein production is established. ESBL-producing Escherichia coli, Salmonella and Klebsiella in chicken and turkey may pose a significant public health risk due to potential transmission between poultry and humans. This review aims to assess the prevalence of ESBL-producing E. coli, Salmonella and Klebsiella phenotypically and genotypically in Italian poultry, identifying the most common genes, detection methods and potential information gaps. An initial pool of 1462 studies found in scientific databases (Web of Sciences, PubMed, etc.) was screened and 29 were identified as eligible for our review. Of these studies, 79.3% investigated both phenotypic and genotypic ESBL expression while ${bla}_{CTX-M}$, ${bla}_{TEM}$ and ${bla}_{SHV}$ were considered as targeted gene families. Large differences in prevalence were reported (0–100%). The ${bla}_{CTX-M-1}$ and ${bla}_{TEM-1}$ genes were the most prevalent in Italian territory. ESBL-producing E. coli, Salmonella and Klebsiella were frequently detected in farms and slaughterhouses, posing a potential threat to humans through contact (direct and indirect) with birds through handling, inhalation of infected dust, drinking contaminated water, ingestion of meat and meat products and the environment. Considering the frequent occurrence of ESBL-producing bacteria in Italian poultry, it is advisable to further improve biosecurity and to introduce more systematic surveillance. Additionally, the focus should be on the wild birds as they are ESBL carriers. Full article

The interactions between magnetic nanoparticles (MNP) and bio-surfaces have impacted key industries such as food, biomedicine, water purification, and agriculture. Bacteria, with their diverse bio-surfaces, offer potential for such interactions. Yet, there is a paucity of research interpreting the dynamics behind bacteria–nanoparticle interactions. Advancing this knowledge could improve the industrial applications. Current research gaps include information about the magnetic nanoparticle-assisted concentration dependence of Bacillus cereus and determination of the rate of bacterial extraction by MNPs such as iron oxide nanoparticles (IONPs). Using magnetic IONPs as the choice of MNP, this study aimed to investigate in vitro the interactions between model bacteria and IONPs, leveraging the bacterial magnetising property. IONPs were synthesised by co-precipitation and characterised. Magnetic capture efficiency was reported for four model bacteria (Bacillus cereus, Escherichia coli, Staphylococcus aureus, and Salmonella typhimurium). The effect of particle concentration on the viability of Bacillus cereus and the rate of magnetic extraction of Bacillus cereus were evaluated. Bacillus cereus had the most robust interaction with IONP (90.34%). While the magnetic extraction was time-dependent, the average rate of magnetic extraction for Bacillus cereus was calculated as 3.617 CFU mL⁻¹/min. Growth inhibition at 1.0, 2.0, and 4.0 mg mL⁻¹ of IONP was significant. Magnetic capture results indicated that members of the Bacillus genus screened for plant growth-promoting traits may be suitable to combine with IONPs for future land application. Full article

The International Agency for Research on Cancer has studied and classified 1045 potential substances. It is therefore important to develop rapid screening methods to identify the mutagenicity of compounds and, further on, the intensity and number of individual mutagenic substances in complex sample mixtures. The current in vitro Ames assay in the microtiter plate format (MPF) uses a pH-sensitive detection as endpoint, however, acidic substances in complex mixtures may interfere the mutagenicity result. Hence, it was transferred to the planar assay format to be more selective for complex mixture testing. The co-culture of Salmonella Typhimurium strains TA98 and TA100 with an optical density of 0.4 at 600 nm was applied on a high-performance thin-layer chromatography silica gel 60 chromatogram and on-surface incubated for 5 h, which period was limited due to zone diffusion. Various positive controls were tested, and 4-nitrochinolin-N-oxide with a limit of detection of 100 ng was established as a positive control. However, due to the shorter incubation time, no mutagenic compounds were detectable or differentiable in the tested perfumes, herbal teas, margarines, and hand creams. This does not mean that the samples are mutagen-free, but it suggests that further improvements to the bioassay are urgently needed to increase the sensitivity and selectivity of the response. Compared to conventional sum value assays, a planar Ames assay performed on the separated and adsorbed sample components advances toxicology research because mutagenic compounds are separated from interfering molecules due to the integrated separation. It thus would provide a more selective detection of mutagens in complex mixtures and allow testing of large sample volumes or concentrated samples without matrix interference. Full article

Background/Objectives: The growing number of households with companion dogs raises concerns. Co-living environments between companion dogs and their owners are linked to a heightened risk of cross-infections from strains such as Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Salmonella, and faecal coliforms. Therefore, this study aims to propose measures for healthy cohabitation by analysing the faecal microbiota of puppies and adult dogs. Methods: We isolated lactic acid bacteria (LAB) from their faeces and assessed their potential to inhibit E. coli, S. aureus, and Salmonella spp. Faecal samples from puppies (<2 months old) and adult dogs (>12 months old) were analysed and compared. Results: The analysis revealed that Lactobacillus dominated puppy faeces, while Bacteroidetes were more abundant in adult dogs. In total, 109 primary LAB candidates were isolated from faecal samples. These isolates underwent secondary screening for acid tolerance, bile salt resistance, acid production, heat resistance, protease activity, and antimicrobial activity against E. coli, S. aureus, and Salmonella spp. Five secondary LAB candidates with probiotic potential were further characterised via morphological and genetic analysis. All five strains were Lactobacillus reuteri, with L. reuteri JJ37, JJ68, JJ69, JJ71, and JJ77 emerging as the final probiotic candidates. Conclusions: They promote healthier cohabitation between dogs and their owners. Full article

This pilot study investigated the presence of potentially zoonotic microorganisms in bat species from Kopaonik National Park, Serbia. A total of 40 individuals from 12 bat species were sampled and screened using microbiological and molecular methods. Salmonella spp., Chlamydia spp., Coxiella burnetii, Francisella tularensis, Leptospira spp., Lyssavirus, Filoviridae, henipaviruses, and SARS-CoV-2 were not detected in any bats. Coronavirus genomes were confirmed in four bats—one Myotis brandtii, two Myotis daubentonii, and one Myotis cf. mystacinus. Sequence analysis identified the presence of alphacoronavirus genomes with high similarity to strains previously found in Europe. Mycoplasma spp. genomes were found in 18 bats (45%), and Rickettsia spp. were detected in five bats (12.5%), although species-level identification was not possible. The findings highlight the presence of certain bacteria and viruses in bats that could have implications for public health, especially in areas with close human–wildlife interaction. Although no direct evidence of high-risk pathogens was found, the results support the importance of continued surveillance and ecological studies on bats, given their role as potential reservoirs. Monitoring bat-associated microorganisms is essential to better understand possible transmission routes and improve the prevention of emerging zoonotic diseases. Full article

The emergence of multidrug-resistant bacterial infections is a major global public health concern. Human health is in danger from microorganisms that have developed resistance to currently used drugs. Honey is well known for its significant activity against antibiotic-resistant bacteria. In this study, the antibacterial properties of honey from various botanical sources in Saudi Arabia against seven significant nosocomial and foodborne pathogens were investigated. The physicochemical properties of four Saudi honey samples—aloe honey (HO1) (Aloe vera L.), anise honey (HO2) (Pimpinella anisum L.), moringa honey (HO4) (Moringa oleifera Lam.), and acacia honey (HO5) (Acacia sp.)—were examined. In addition, they were screened for antibacterial activity against ESKAPE pathogens (Enterobacter faecalis, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella Typhimurium, Escherichia coli, and Enterobacter sp.) and anti-biofilm activity against four pathogenic bacteria strains: S. aureus, P. aeruginosa, S. typhimurium, and E. coli. ¹H NMR profiling and multivariate analysis (PCA and PLS-DA) were performed. Aloe honey (HO1) was the most distinct sample based on MVDA and its antibacterial activity, and it exhibited anti-biofilm activity against most biofilm-forming microorganisms. Its metabolic profile was deduced using LC-MS, and the resulting annotated compounds were docked against several β-lactamase enzyme classes. The results reveal the potential of honey-derived compounds to inhibit β-lactamases due to the presence of gallic acid hexoside and rosmarinic acid, suggesting their potential as competitive inhibitors. Our findings suggest that further honey antibacterial compounds could offer a novel approach to overcoming antibiotic resistance by targeting and inhibiting β-lactamase enzymes. Full article

Colitis in equines has high morbidity and mortality rates, which severely affects the development of the equine-breeding industry. With the issuance of antibiotic bans, there is an urgent need for healthier and more effective alternatives. In recent years, probiotics have been widely used as microbial feed additives in animal husbandry, playing a crucial role in preventing and treating diarrhea and regulating host immune function. In this study, we isolated and screened a strain with rapid and stable acid production using bromocresol purple, litmus milk coloration tests, and acid production performance assessments. Based on morphological characteristics, physiological and biochemical properties, and 16S rDNA identification, the strain was identified as Pediococcus pentosaceus and named M6. The Pediococcus pentosaceus M6 exhibited stable growth and tolerance to high temperatures, acid and bile salt concentrations, and simulated gastrointestinal fluid environments. The M6 strain demonstrated good antibacterial effects against Escherichia coli, Staphylococcus aureus, and Salmonella. The M6 strain did not produce hemolysis zones on Columbia blood agar plates, indicating its high safety, and was found to be insensitive to 12 antibiotics, including cephalexin and neomycin. Additionally, intervention in mice with dextran sulfate sodium (DSS)-induced colitis alleviated weight loss and shortened colon length. To a certain extent, it regulated the expression of inflammatory cytokines and the gut microbiota within the body and reduced inflammatory cell infiltration and intestinal barrier damage. In summary, the isolated Pediococcus pentosaceus M6 strain exhibited excellent probiotic properties and could alleviate DSS-induced colitis in mice, suggesting its potential application value as a probiotic in animal husbandry. Full article

The detection of foodborne pathogens is a critical aspect of ensuring food safety. Traditional methods rely on time-intensive enrichment steps and pathogen-specific assays, extending testing timelines and limiting throughput. This study evaluates an enrichment-free, multiplexed pathogen detection workflow combining the Pathotrak system for bacterial separation and the Neogen Molecular Detection System (MDS) for detection. The workflow enables simultaneous detection of Salmonella, Escherichia coli O157, Listeria monocytogenes, Listeria spp., and Campylobacter in poultry samples, significantly reducing the time taken to screen samples requiring further evaluation. The system’s performance was assessed using inoculated chicken samples over a range of bacterial concentrations (10²–10⁸ CFU/mL). The MDS system demonstrated robust detection for most pathogens, with strong correlations between theoretical inoculation levels and MDS-calculated concentrations (R² > 0.85 for all pathogens). However, detection variability was observed at lower concentrations for Salmonella and Listeria monocytogenes. The system maintained high sensitivity and specificity, achieving a Cohen’s Kappa coefficient for E. coli and Campylobacter. This study highlights the potential of enrichment-free, multiplex detection to streamline food safety testing by reducing the time to results, enhancing efficiency, and providing reliable pathogen quantification across multiple targets. Full article

Plastic pollution is a global emerging concern, but in the Arctic Ocean, the role of the plastisphere as a potential carrier of pathogens and antibiotic-resistant bacteria is unknown yet. An initial assessment of the spread of these target bacteria through their colonization of plastic particles, attributed to the micro-sized fraction (less than 5 mm, named microplastics, MPs), was carried out across the 75° N transect (Greenland Sea). To fill the knowledge gaps regarding the bacterial community associated withmicroplastics (MPs)—belonging to the so-called “plastisphere”—and the potential risks related to their spread, our study focused on the abundance and taxonomic composition of the plastisphere, including potential pathogenic and antibiotic-resistant bacteria, using a culture-dependent approach. MPs particles were collected through a Manta net, and decimal dilutions were cultured on Marine agar plates to estimate the abundance of culturable heterotrophic bacteria. For the search of target pathogenic bacterial species (Escherichia coli, Enterococcus spp., Salmonella spp., potentially pathogenic Vibrio spp., and Staphylococcus aureus), small volumes were inoculated into selective culture media using aspread plate directly or after enrichment. Screening of the antibiotic susceptibility profiles of the bacterial isolates was performed to assess the presence of antibiotic-resistant bacteria. The culturable heterotrophic bacterial community was dominated by members of the phyla Gammaproteobacteria and Actinobacteria, with bacterial isolates assigned to the genera Psychrobacter, Pseudoalteromonas, Shewanella, and Arthrobacter. Selective enrichments resulted in the detection of target bacterial pathogens, mostly identified as potentially pathogenic Vibrios spp., in the examined samples. The antibiotic susceptibility profiles pointed out that multiple antibiotic-resistant bacteria were also isolated, suggesting the need to shed light on the potential risks to human and animal health deriving from the plastisphere in remote cold regions as well. Full article

As of today, bacteriological identification and the molecular approach PCR are considered the gold standards for Salmonella spp. detection. However, these methods are time-consuming and costly due to the requirements for enrichment and nucleic acid extraction. In this study, we evaluated the reliability of a developed colorimetric loop-mediated isothermal amplification (cLAMP) assay targeting the hilA gene, using Phenol Red as an amplification indicator. Given that Phenol Red is pH-dependent, and to develop an extraction-free test, we evaluated chicken meat pretreatment and thermal treatment. First, we assessed the reliability of this test using a pure culture of Salmonella spp. and then in 50 chicken samples pretreated with optimal NaOH concentrations under standardized conditions. Samples representing extreme pH values were artificially contaminated and subjected to DNA extraction and a heat-treatment protocol. Serial dilutions of these products served as templates for LAMP reactions. The assay sensitivity was estimated to be around 3.9 CFU/µL of pure bacterial culture. In contrast, in biological samples, we detected up to 10 CFU/µL using DNA extraction, while heat treatment successfully amplified the initial solution and even some dilutions up to 10³ CFU/µL. In conclusion, our cLAMP assay demonstrated good sensitivity and provided clear evidence of its potential for in-field use without relying on prior enrichment steps and DNA extraction. Full article