Staphylococcus Research Articles

Effects of staphylococcal enterotoxin and fungal sensitization on clinical outcomes of asthma

BackgroundStaphylococcal enterotoxin and fungal sensitization can influence asthma severity; however, the effects on the clinical outcomes of asthma remain unclear. This study investigated the clinical outcomes of asthma in patients with or without staphylococcal enterotoxin sensitization and further analyzed the effects of fungal sensitization on the clinical outcomes of patients with staphylococcal enterotoxin sensitization.MethodsThis retrospective study included patients with asthma who had undergone a staphylococcal enterotoxin-specific immunoglobulin E test at our hospital between January and August 2021. Data on clinical manifestations, medication use, pulmonary function, clinic and emergency room visits and hospitalization were collected from 106 patients.ResultsThe prevalence of staphylococcal enterotoxin sensitization was 27.3%. Among the patients with staphylococcal enterotoxin sensitization, 50% also presented with fungal sensitization. The risk of hospitalization and emergency room visits was higher among patients with staphylococcal enterotoxin sensitization than among those without, as was the need for high-level asthma treatment, including triple inhaler therapy and biologics. After the 12-month Program enrollment, the rates of emergency room visits and hospitalization were similar in the two cohorts. Patients with concomitant staphylococcal enterotoxin and fungal sensitization exhibited a notable post-treatment decline in pulmonary function.ConclusionAdherence to asthma treatment protocols was shown to improve clinical outcomes in patients with or without staphylococcal enterotoxin sensitization. Among patients with staphylococcal enterotoxin sensitization, those with concomitant fungal sensitization were more likely to exhibit a rapid decline in pulmonary function during a 1-year high-level treatment program.

The identification of a SARs-CoV2 S2 protein-derived peptide with super-antigen-like stimulatory properties on T-cells.

Severe COVID-19 can trigger a cytokine storm, leading to acute respiratory distress syndrome (ARDS) with similarities to superantigen-induced toxic shock syndrome. An outstanding question is whether SARS-CoV-2 protein sequences can directly induce inflammatory responses. In this study, we identify a region in the SARS-CoV-2 S2 spike protein with sequence homology to bacterial super-antigens (termed P3). Computational modeling predicts P3 binding to sites on MHC class I/II and the TCR that partially overlap with sites for the binding of staphylococcal enterotoxins B and H. Like SEB and SEH peptides, P3 stimulated 25-40% of human CD4+ and CD8+ T cells, increasing IFN-γ and granzyme B production. viSNE and SPADE profiling identified overlapping and distinct IFN-γ and GZMB subsets. The super-antigenic properties of P3 were further evident by its selective expansion of T cells expressing specific TCR Vα and Vβ chain repertoires. In vivo experiments in mice revealed that the administration of P3 led to a significant upregulation of proinflammatory cytokines IL-1β, IL-6, and TNF-α. While the clinical significance of P3 in COVID-19 remains unclear, its homology to other mammalian proteins suggests a potential role for this peptide family in human inflammation and autoimmunity.

Bifunctional nanobody facilitates a colorimetric and fluorescent dual-mode immunoassay of Staphylococcal enterotoxin A

Immunoassay is a diagnostic tool based on the specific binding of antibodies and antigens with widespread applications. Nonetheless, several research obstacles, like poor specific antibodies, the poisonous reagents and unstable results, still remain challenges. Herein, we innovatively reported a colorimetric and fluorescent dual-mode immunoassay based on the bifunctional nanobody for SEA detection. Benefiting from the advantages of nanobodies, the bifunctional protein with both recognition and catalysis was built to identify and catalyze with efficiency to generate the first colorimetric signal. Meanwhile, the introduction of quinine as the natural source of the second fluorescent signal greatly improved the stability and safety of detection. In addition, the proposed method was successfully applied to detecting SEA in food samples with high accuracy and stability. This study integrated the bifunctional nanobody with eco-friendly fluorescent product to provide a specific and green platform for the detection of foodborne toxins.

Magnetic-plasmonic blackbody enhanced lateral flow immunoassay of staphylococcal enterotoxin B

Staphylococcal enterotoxin B (SEB) in food is a serious health risk, making rapid and accurate detection methods essential. Herein, we synthesized a magnetic plasmonic blackbody, Fe3O4@Au/PDA, by coating a gold/polydopamine (Au/PDA) layer onto an Fe3O4 core. This Fe3O4@Au/PDA exhibits broadband absorption, excellent stability, and rapid magnetic response, making it ideal for use as a magnetic separation tool and colorimetric signal amplifier. We integrated Fe3O4@Au/PDA into a lateral flow immunoassay (LFIA) for ultrasensitive SEB detection, combining magnetic enrichment with enhanced colorimetric signal output. The Fe3O4@Au/PDA-based LFIA achieved a detection limit of 0.19 ng/mL, approximately 41 times lower than traditional gold nanoparticle-based LFIA. Its real-world applicability was tested in various food samples (milk, milk powder, apple juice, and lettuce) with recoveries between 82.4 % and 111.2 % and a coefficient of variation below 12.6 %. Collectively, the designed Fe3O4@Au/PDA shows great promise as a novel multifunctional signal amplification label, advancing the design and development of ultrasensitive LFIA for various fields, such as food safety detection.

Phage-Derived Endolysins Against Resistant Staphylococcus spp.: A Review of Features, Antibacterial Activities, and Recent Applications.

Antimicrobial resistance is a significant global public health issue, and the dissemination of antibiotic resistance in Gram-positive bacterial pathogens has significantly increased morbidity, mortality rates, and healthcare costs. Among them, Staphylococcus, especially methicillin-resistant Staphylococcus aureus (MRSA), causes a wide range of diseases due to its diverse pathogenic factors and infection strategies. These bacteria also present significant issues in veterinary medicine and food safety. Effectively managing staphylococci-related problems necessitates a concerted effort to implement preventive measures, rapidly detect the pathogen, and develop new and safe antimicrobial therapies. In recent years, there has been growing interest in using endolysins to combat bacterial infections. These enzymes, which are also referred to as lysins, are a unique class of hydrolytic enzymes synthesized by double-stranded DNA bacteriophages. They possess glycosidase, lytic transglycosylase, amidase, and endopeptidase activities, effectively destroying the peptidoglycan layer and resulting in bacterial lysis. This unique property makes endolysins powerful antimicrobial agents, particularly against Gram-positive organisms with more accessible peptidoglycan layers. Therefore, considering the potential benefits of endolysins compared to conventional antibiotics, we have endeavored to gather and review the characteristics and uses of endolysins derived from staphylococcal bacteriophages, as well as their antibacterial effectiveness against Staphylococcus spp. based on conducted experiments and trials.

Human-immunodeficiency virus infection associated with the impaired Th1 and pro-inflammatory cytokine response in latent tuberculosis-infected individuals: A comparative cross-sectional study.

Tuberculosis (TB) and HIV co-infections are extensively overlapping, especially in developing countries. HIV infection is known as a major risk factor for the reactivation of latent TB into active TB. Although not fully understood and needs further study, HIV infection might enhance the reactivation of latent TB by breaching immune control mechanisms. We investigated the influence of HIV infection on the cytokine response of LTB-infected individuals. Heparinized venous blood was collected from 40 ART-naïve HIV-infected and 30 HIV-negative healthy controls for LTB screening, plasma collection, and PBMC isolation and stimulation. The level of cytokines in plasma and their production by PBMCs stimulated with purified protein derivative (PPD), staphylococcus enterotoxin B (SEB), or unstimulated PBMCs were analyzed using a cytometric bead array (CBA) assay. PPD-induced IL-2 by PBMCs was higher in LTB-infected groups compared with HIV-negative LTB-negative groups (p = 0.0015). When LTB-infected groups were co-infected with HIV (HIV+LTB+), the IL-2 (p < 0.0001) and IFN-gamma (p = 0.0144) production by PPD-stimulated PBMCs was reduced. The level of IL-2 (p = 0.0070), IL-6 (p = 0.0054), and TNF-alpha (p = 0.0045) in plasma were lower in HIV+LTB+ individuals compared with HIV-negative LTB-positive (HIV-LTB+) groups. Our findings suggested that HIV co-infection in LTB-positive individuals is associated with the diminished production of PPD-induced Th1 (IFN-gamma and IL-2) cytokines by PBMCs and in the plasma level of IL-2 and proinflammatory cytokines (IL-6 and TNF-alpha).

Characterization and complete genome sequence of highly lytic phage active against methicillin-resistant Staphylococcus aureus (MRSA) isolated from Egypt

BackgroundMethicillin-Resistant Staphylococcus aureus (MRSA) is one of the most resistant bacteria to antibiotics. S. aureus is an important, widespread pathogen that can cause a variety of infectious diseases in humans and animals. Phages have been recognized as natural, safe, highly specific and effective alternatives agents to antibiotics for preventing and treating bacterial infections caused by MRSA. Therefore, this study aims at the characterization of a novel isolated lytic phage, vB_SauP_ASUmrsa123.MethodsIsolates of Staphylococcus aureus MRSA were obtained on Mannitol Salt Agar and Baird Parker Agar plates and confirmed using VITEK 2. Sewage and clinical samples were used to isolate specific phages for S. aureus MRSA, and plaque assays were used for host range determination on Luria-Bertani (LB) media. The phage morphology of the isolated phage was determined by transmission electron microscopy. The phage’s whole genome sequencing was identified.ResultsA total of 25 isolates of Staphylococci were obtained from different clinical sources and showed typical colonies on Baird-Parker and Mannitol Salt Agar plates. The VITEK 2 automated system revealed that all 25 isolates were confirmed as S. aureus (MRSA). Two of the most antibiotics-resistant isolates were further confirmed using 16S ribosomal RNA sequencing. A lytic phage was detected against the MRSA isolates tested In Vitro, namely vB_SauP_ASUmrsa123. The phage belonged to Rountreeviridae family based on morphological properties observed by TEM and the host range of the isolated phage was tested on the 25 clinical MRSA isolates in Vitro. The one-step growth curve of the isolated phage showed that the latent period was about 55 min, and the burst size was estimated at 167 PFU. The whole genome sequencing and annotation of genes revealed that phage vB_SauP_ASUmrsa123 contained a linear dsDNA with a size of about 17,155 bp with predicted 24 ORFs. Analysis of its genome provides valuable information approximately the variety of phages belonging to the staphylococcal phages class I.ConclusionA lytic Podo Phage vB_SauP_ASUmrsa123 was identified against S. aureus MRSA isolates and its genome was sequenced. The phage was found to be eligible for potential application in biocontrol.

Production of bacteriocin-like inhibitory substance (BLIS) by Staphylococcus spp. isolates from dogs.

In the present study, 39 canine isolates of Staphylococcus spp. were tested for antimicrobial substance (AMS) production. Seven AMS producers were identified, whose products exhibited a non-acidic character and a proteinaceous nature, therefore being considered bacteriocin-like inhibitory substances (BLIS). The producer strains of BLIS P1, P16 and I3 showed a broad spectrum of antimicrobial activity. Human, veterinary and plant pathogens, such as Listeria monocytogenes, Klebsiella pneumoniae, Staphylococcus spp. and Clavibacter michiganensis, were among the inhibited micro-organisms, suggesting the potential biotechnological application of these peptides. MALDI-TOF mass spectrometry and 16S rDNA sequencing identified the producer strains of BLIS P1, P16 and I3 as Staphylococcus pseudintermedius P1, Staphylococcus schleiferi P16 and Staphylococcus pseudintermedius I3. The plasmid profile of these strains suggests that the BLIS production is linked to biosynthetic genes located on plasmids. PCR analyses revealed that BLIS P1, P16 and I3 are different from 11 staphylococcins already described in the literature and that their genomic DNAs do not carry the most prevalent staphylococcal enterotoxin genes. The highest levels of BLIS production were achieved after 18-24h of growth of the producer strains in TSB medium. Moreover, BLIS P1 and I3 exhibited high resistance to temperature and pH variations, and BLIS P16 maintained 100% of its activity in almost all conditions tested. The characteristics associated with BLIS P1, P16 and I3 described in this work encourage further investigation of these substances, in addition to this study being the first report of BLIS production by a strain of S. schleiferi.

Investigation of Various Toxigenic Genes and Antibiotic and Disinfectant Resistance Profiles of Staphylococcus aureus Originating from Raw Milk.

This study investigated the toxigenic genes and antimicrobial resistance profiles of Staphylococcus aureus strains isolated from 260 raw milk samples collected from dairy farms in Türkiye. The results indicated that 60.7% of staphylococcal enterotoxin genes (sea, seb, sed, seg, sei, sej, sek, seq, sem, seo, and seu) and 21.4% of the tst and eta genes were positive, with most enterotoxin-positive samples carrying more than one gene. The sec, see, seh, sel, sen, sep, and etb genes were not identified in any samples. The prevalence of antibiotic resistance genes (mecA, blaR, blaI, blaZ, vanA, ermT, tetK, aac/aph, ant, dfrA, tcaR, IS256, and IS257) was high at 89.2%, with bla being the most frequently detected gene (75%). The mecA gene was present in 14.2% of samples, while tcaR was detected in 78.5%. Nevertheless, the mecC was not identified. Disinfectant resistance genes (qacA/B, qacC, qacJ, smr) were detected in 21.4% of the samples. The results of the disk diffusion test showed that 64.2% of strains were resistant to penicillin G and ampicillin, with additional resistance found for cefoxitin, teicoplanin, levofloxacin, norfloxacin, and other antibiotics. These findings highlight a significant public health and food safety risk associated with raw milk due to the presence of S. aureus strains with toxigenic genes and high antimicrobial resistance.

Rapid and sensitive detection of staphylococcal enterotoxin E using a time-resolved fluorescence immunochromatography assay

Staphylococcal food poisoning is a significant foodborne illness caused by staphylococcal enterotoxins (SEs). Immunoassays have become the primary method for rapidly detecting harmful bacteria and toxins because of their excellent sensitivity and specificity. However, these assays have limitations in that they cannot differentiate between types of SEs and do not provide rapid, on-site, quantitative testing. In this study, a time-resolved fluorescence immunochromatography assay (TRFICA) was developed specifically for detecting staphylococcal enterotoxin E (SEE), which is commonly found in dairy products. Compared with a double antibody sandwich enzyme-linked immunosorbent assay, which had a detection limit of 0.028 ng/mL, TRFICA demonstrated comparable sensitivity, enabling SEE quantification with a detection limit as low as 0.081 ng/mL in infant formula. Validation by spiking infant formula samples confirmed no cross-reactivity with analogs (recoveries ranged from 93.17% to 128.77%). Furthermore, with an 8-min reaction time and interpretation delivered by a portable TRFICA strip reader, our method demonstrates potential for use in mobile and on-site detection. This study describes a rapid, easy, and reliable method for detecting trace levels of SEE in infant formula, which could serve as an early screening tool toward preventing food poisoning in infants and children.

Immunomodulatory effects of cysteamine and its potential use as a host-directed therapy for tuberculosis.

Cysteamine, a drug approved to treat cystinosis, has been proposed as a host-directed therapy for M. tuberculosis (Mtb) and SARS-CoV-2. The impact of cysteamine on the immune responses has not been fully investigated. We aimed to in vitro evaluate the immunomodulatory effects of cysteamine on peripheral blood mononuclear cells (PBMCs) using the purified protein derivative (PPD) as a recall antigen, and an unspecific stimulus as staphylococcal enterotoxin B (SEB). PBMCs isolated from subjects with tuberculosis infection (TBI), those with tuberculosis disease (TB), and healthy controls (HC) were in vitro stimulated with PPD or SEB and treated or not with cysteamine at different concentrations (50 µM-400 µM) for 6 hours (h) and 24 h. We evaluated the T helper1 (Th1) and T cytotoxic1 (Tc1) cell cytokine production by flow cytometry and immune-enzymatic assays. In HC, we also evaluated apoptosis and/or necrosis by flow cytometry. We observed an immunomodulatory effect of cysteamine at 400 µM in PBMCs from TB and TBI subjects. It significantly reduced PPD-specific Th1 responses at 24 h and at 6 h (p=0.0004 and p=0.0009, respectively), and a similar non-significant trend was observed with cysteamine at 200 µM (p=0.06 at 24 h and p=0.14 at 6 h). Moreover, cysteamine at both 400 µM (p<0.0001 and p=0.0187 at 24 h, respectively, and p<0.0001 at 6 h for both) and 200 µM (p=0.0119 and p=0.0028 at 24 h and p=0.0028 and p=0.0003 at 6 h, respectively) significantly reduced SEB-induced Th1 and Tc1 responses. Furthermore, we found that cysteamine induced morphological lymphocyte changes and significantly reduced the lymphocyte percentage in a dose- and time-dependent manner. Cysteamine at 400 µM induced 8% late apoptosis and 1.6% necrosis (p<0.05) at 24 h. In contrast, despite significant differences from untreated conditions (p<0.05), cysteamine at 400 µM for 6 h induced approximately 1% late apoptosis and 0.1% necrosis in the cells. High doses of cysteamine in vitro reduce the percentages of PPD- and SEB-induced Th1 and Tc1 cells and induce late apoptosis and necrosis. Differently, cysteamine at lower doses retains the immunomodulatory effect without affecting cell viability. These findings suggest cysteamine as a potential adjunct to antimicrobial regimens as in the TB or COVID-19 field, for its ability to reduce the inflammatory status.

Virus-specific Th17 Cells Are Induced by Human Cytomegalovirus after Renal Transplantation.

CMV infection and Th17 cells are independently associated with increased risk for late allograft loss after renal transplantation. Although CMV-specific Th17 cells are detectable in animal models and nontransplant clinical populations, evidence linking CMV and Th17 cells after renal transplantation remains unclear. This prospective observational study evaluated a cohort of renal transplant recipients during 12 mo posttransplant to assess the presence of CMV-specific Th17 cells in peripheral blood and their relationship to pretransplant CMV serostatus and CMV DNAemia. CMV-specific Th17 cells were identified among CMV serostatus donor (D)+ and/or recipient (R)+ recipients and expanded during both primary (D+/R-) and reactivated (D+/R+, D-/R+) CMV DNAemia. A subset of CMV-specific Th17 cells coexpressed IFN-γ, indicating a Th1/17 phenotype. These Th17 and Th1/17 cells expressed CCR6, CCR5, activation and terminal differentiation markers (CD95, OX40, HLA-DR, CD57), and a central/effector memory phenotype. CMV-specific Th1/17 cells expressed activating/inhibitory receptors (CD57, 4-1BB, CD160, CTLA-4, PD-1) at higher frequencies than Th17 cells. In contrast, staphylococcal enterotoxin B-induced Th17 cells did not expand during CMV DNAemia, did not differ between CMV serostatus groups over time, expressed CCR6, predominantly coexpressed TNF-α, and had lower expression of activating and inhibitory receptors than pp65-specific Th17 and Th1/17 cells. These data show that CMV-specific Th17 cells expand during episodes of CMV DNAemia among renal transplant recipients, and that these virus-specific Th17 and Th1/17 cells have distinct phenotypes from global circulating Th(1)/17 cells. These results suggest a potential proinflammatory pathway by which CMV-induced Th17 cells may contribute to allograft injury, increasing risk for late allograft loss.

Direct Mapping of Polyclonal Epitopes in Serum by HDX-MS.

Elucidating the interactions that drive antigen recognition is central to understanding antibody-mediated protection and is vital for the rational design of immunogens. Often, structural knowledge of epitopes targeted by antibodies is derived from isolated studies of monoclonal antibodies, for which numerous structural techniques exist. In contrast, there are very few approaches capable of mapping the full scope of antigen surfaces targeted by polyclonal sera through the course of a natural antibody response. Here, we develop an approach using immobilized antigen coupled to hydrogen/deuterium exchange with mass spectrometry (HDX-MS) to probe epitope targeting in the context of the fully native serum environment. Using the well-characterized Staphylococcal enterotoxin B (SEB) as a model system, we show that complex combinations of epitopes can be detected and subtle differences across different antisera can be discerned. This work reveals new insight into how neutralizing antibodies and antisera target SEB and, more importantly, establishes a novel method for directly mapping the epitope landscape of polyclonal sera.

Actual opportunistic ocular surface microflora and its sensitivity to antimicrobials and bacteriophages in patients with cataracts

Background: Species of opportunistic microflora often are the pathogenic agents that causes endophthalmitis in cataract surgery. Frequently microorganisms are characterized by resistance to several antimicrobial medicaments, which limits the ability to choose an effective agent. This problem requires a detailed study and monitoring of the sensitivity of ocular surface microflora. Aim: To study the species composition of the ocular surface microflora patients before phacoemulsification and to evaluate the antimicrobial activity of antimicrobial medicaments including antiseptics and bacteriophages. Materials and methods: A total of 60 patients were examined before phacoemulsification. The sensitivity to antimicrobial medicaments and bacteriophages was determined of microorganisms isolated from three loci (conjunctival cavity, eyelid margin, lacrimal ducts). Results: Among all microorganisms isolated, there was a significant prevalence of Staphylococcus epidermidis — 48,4 %. Almost all antiseptics showed high antimicrobial activity. All staphylococci cultures were sensitive to staphylococcal bacteriophage number 2. The smallest proportion of resistant microorganisms to antimicrobial medicaments used in ophthalmology was registered in the group of aminoglycosides. Conclusions: Antimicrobial activity of the investigated medicaments was different among different bacterial species. The sensitivity of microflora changes over time, therefore it is appropriate to carry out periodic monitoring and adjust antimicrobial prophylaxis regimens based on the results received.

Pregnancy impacts allergy-related differences in the response to a type-1 stimulus, staphylococcal enterotoxin A.

Pregnancy impacts allergy-related differences in the response to a type-1 stimulus, staphylococcal enterotoxin A.

Staphylococcus aureus in Dairy Industry: Enterotoxin Production, Biofilm Formation, and Use of Lactic Acid Bacteria for Its Biocontrol.

Staphylococcus aureus is a well-known pathogen capable of producing enterotoxins during bacterial growth in contaminated food, and the ingestion of such preformed toxins is one of the major causes of food poisoning around the world. Nowadays 33 staphylococcal enterotoxins (SEs) and SE-like toxins have been described, but nearly 95% of confirmed foodborne outbreaks are attributed to classical enterotoxins SEA, SEB, SEC, SED, and SEE. The natural habitat of S. aureus includes the skin and mucous membranes of both humans and animals, allowing the contamination of milk, its derivatives, and the processing facilities. S. aureus is well known for the ability to form biofilms in food processing environments, which contributes to its persistence and cross-contamination in food. The biocontrol of S. aureus in foods by lactic acid bacteria (LAB) and their bacteriocins has been studied for many years. Recently, LAB and their metabolites have also been explored for controlling S. aureus biofilms. LAB are used in fermented foods since in ancient times and nowadays characterized strains (or their purified bacteriocin) can be intentionally added to prolong food shelf-life and to control the growth of potentially pathogenic bacteria. Regarding the use of these microorganism and their metabolites (such as organic acids and bacteriocins) to prevent biofilm development or for biofilm removal, it is possible to conclude that a complex network behind the antagonistic activity remains poorly understood at the molecular level. The use of approaches that allow the characterization of these interactions is necessary to enhance our understanding of the mechanisms that govern the inhibitory activity of LAB against S. aureus biofilms in food processing environments.

A comprehensive study on the autochthonous microbiota, volatilome, physico-chemical, and morpho-textural features of Montenegrin Njeguški cheese

The present study aims to deepen the knowledge of the microbiota, gross composition, physico-chemical and morpho-textural features, biogenic amines content and volatilome of Njeguški cheese, one of the most popular indigenous cheeses produced in Montenegro. Cheese samples were collected in duplicate from three different batches produced by three Montenegrin artisan producers. For the first time, the microbiota of Njeguški cheese was investigated using both culture-dependent techniques and metagenomic analysis. Coagulase positive staphylococci viable counts were below the detection limit of the analysis (<1 log cfu g−1). Salmonella spp., Listeria monocytogenes and staphylococcal enterotoxins were absent. However, relatively high viable counts of Enterobacteriaceae, Escherichia coli, Pseudomonadaceae and eumycetes were detected. Metataxonomic analysis revealed a core microbiome composed of Lactococcus lactis, Streptococcus thermophilus, Debaryomyces hansenii, and Kluyveromyces marxianus. Furthermore, the detection of opportunistic pathogenic yeasts such as Magnusiomyces capitatus and Wickerhamiella pararugosa, along with the variable content of biogenic amines, suggests the need for increased attention to hygienic conditions during Njeguški cheese production. Significant variability was observed in humidity (ranging from 38.37 to 45.58 %), salt content (ranging from 0.70 to 1.78 %), proteins content (ranging from 21.42 to 25.08 %), ash content (ranging from 2.97 to 4.05 %), hardness, springiness, and color among samples from different producers. Gas chromatography-mass spectrometry analysis showed a well-defined and complex volatilome profile of the Njeguški cheese, with alcohols (ethanol, isoamyl alcohol, phenetyl alcol), esters and acetates (ethyl acetate, ethyl butanoate, isoamyl acetate), ketones (acetoin, 2-butanone), and acids (acetic, butanoic, hexanoic acids) being the main chemical groups involved in aroma formation. This research will provide new insights into the still poorly explored identity of Njeguški cheese, thus serving as a first baseline for future studies aimed at protecting its tradition.

Electrochemical aptasensor for sensitive detection of staphylococcal enterotoxin type A in milk and fruit juice.

Anaptamer-based electrochemical sensor for the sensitive detection of staphylococcal enterotoxin type A(SEA) is presented. The truncated aptamer AptSEA1.4 used in this work was screened using computational techniques, which reduced the cost of the SELEX screening process. The aptamer-SEA interactions were confirmed by employing circular dichroism (CD) and fluorescence spectroscopy. Afterwards, for developing an electrochemical aptasensor, a fabricated GNR/FTO aptasensor was prepared and characterized using scanning electron microscopy-energy-dispersive X-ray analysis (SEM-EDX), atomic force microscopy (AFM), cyclic voltammetry (CV), and square wave voltammetry (SWV). A detailed investigation of aptamer and SEA interaction in the presence of various experimental conditions was also conducted through SWV and electrochemical impedance spectroscopy (EIS). The aptamer exhibits a strong affinity for SEA, with a dissociation constant (Kd) of 19.93nM. The aptasensor is sensitive, with a lower limit of detection of 12.44pgmL-1. It has good stability, repeatability, and specificity and has displayed highly specific and sensitive detection SEA in spiked packaged mixed fruit juice and milk, with a recovery of 95-110%. The aptasensor has highpromise for detecting SEA in other food items.

A foodborne outbreak caused by staphylococcal enterotoxins in cheese sandwiches in northern Italy

Staphylococcus aureus can produce numerous toxins, including staphylococcal enterotoxins, namely, SEs, SEA to SEE, SEG to SEI, and SER to SET. They have demonstrated emetic activity and can cause food poisoning outbreaks (FBOs). Here, we report a multidisciplinary investigation conducted by authorities competent in food safety in collaboration with veterinary and health and hygiene services. The issue was foodborne intoxication which involved eight members (aged 12–74 years) of the same family. Notification reported that time to symptom onset was about 3 hours after lunch, which suggests that the food contained preformed toxins. Ham and cheese used for the preparation of sandwiches consumed by all symptomatic relatives were suspected to be the source of FBO. The day after symptoms appeared, samples were collected at the restaurant and delivered to the food safety laboratory. All analyses performed on official food samples are validated according to ISO 17025:2017 and accredited. The cheese subsamples were all positive for coagulase-positive staphylococci CPS (range: 1.1*103 CFU/g to 8.1*103 CFU/g). The pooled sample tested positive for staphylococcal enterotoxin D (SED) at 0.649 ng/g. This concentration can cause symptoms of FBO. Following the notification of suspected food poisoning, a rapid response by the district food safety agency is necessary. In the case described here, the multidisciplinary collaboration facilitated the collection of samples at the food business plant aimed at identifying a suspected source of intoxication and to withdraw unsafe food from the market.

Helper T Cells are Hyperactive and Contribute to the Dysregulation of Antibody Production in Patients with Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a systemic autoimmune disease, mediated by a complex interaction between B cells and various subsets of T cells. Dysfunction of helper T (Th) and regulatory T (Treg) cells may contribute to the breakdown of self-tolerance and the progression of autoimmune disease. In this study, we investigated the activity of Th and Treg cells on the differentiation of autologous B cells in vitro using cell cultures from the peripheral blood of healthy controls (HCs) and RA patients. The expressions of programmed death 1 (PD-1) and IL-21 were monitored as activation markers for Th cells. Unstimulated Th cells from RA patients showed remarkably higher PD-1 expression than HC samples. Stimulation of Th cells from RA patients with Staphylococcus enterotoxin B (SEB) in the presence of B cells significantly induced their PD-1 and IL-21 expression at a considerably higher level in RA compared to HCs, and Treg cells did not affect IL-21 production. When monitoring B-cell differentiation, a significantly higher frequency of plasma cells was observed, even in unstimulated samples of RA patients compared to HCs. In the SEB-stimulated co-cultures of the RA samples, plasma cell frequency and IgG production were considerably higher than in HCs and were not significantly affected by Tregs. These findings demonstrate that Th cells are constitutively active in RA, and their hyperactivity upon interaction with diseased B cells may lead to uncontrolled antibody production.