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Emerging Infectious Diseases Dec 2023Genomic data on the foodborne pathogen Listeria monocytogenes from Central America are scarce. We analyzed 92 isolates collected during 2009-2019 from different regions...
Genomic data on the foodborne pathogen Listeria monocytogenes from Central America are scarce. We analyzed 92 isolates collected during 2009-2019 from different regions in Costa Rica, compared those to publicly available genomes, and identified unrecognized outbreaks. Our findings suggest mandatory reporting of listeriosis in Costa Rica would improve pathogen surveillance.
Topics: Humans; Listeria monocytogenes; Foodborne Diseases; Costa Rica; Food Microbiology; Listeriosis; Disease Outbreaks
PubMed: 37987595
DOI: 10.3201/eid2912.230774 -
Signal Transduction and Targeted Therapy Feb 2024Memory CD8 T cell generation is crucial for pathogen elimination and effective vaccination against infection. The cellular and molecular circuitry that underlies the...
Memory CD8 T cell generation is crucial for pathogen elimination and effective vaccination against infection. The cellular and molecular circuitry that underlies the generation of memory CD8 T cells remains elusive. Eosinophils can modulate inflammatory allergic responses and interact with lymphocytes to regulate their functions in immune defense. Here we report that eosinophils are required for the generation of memory CD8 T cells by inhibiting CD8 T cell apoptosis. Eosinophil-deficient mice display significantly impaired memory CD8 T cell response and weakened resistance against Listeria monocytogenes (L.m.) infection. Mechanistically, eosinophils secrete interleukin-4 (IL-4) to inhibit JNK/Caspase-3 dependent apoptosis of CD8 T cells upon L.m. infection in vitro. Furthermore, active eosinophils are recruited into the spleen and secrete more IL-4 to suppress CD8 T cell apoptosis during early stage of L.m. infection in vivo. Adoptive transfer of wild-type (WT) eosinophils but not IL-4-deficient eosinophils into eosinophil-deficient mice could rescue the impaired CD8 T cell memory responses. Together, our findings suggest that eosinophil-derived IL-4 promotes the generation of CD8 T cell memory and enhances immune defense against L.m. infection. Our study reveals a new adjuvant role of eosinophils in memory T cell generation and provides clues for enhancing the vaccine potency via targeting eosinophils and related cytokines.
Topics: Mice; Animals; CD8-Positive T-Lymphocytes; Listeriosis; Interleukin-4; Eosinophils; Memory T Cells
PubMed: 38413575
DOI: 10.1038/s41392-024-01752-0 -
Innate Immunity Aug 2023The study of cellular immune responses in animal disease models demands detailed knowledge of development, function, and regulation of immune cells, including natural... (Review)
Review
The study of cellular immune responses in animal disease models demands detailed knowledge of development, function, and regulation of immune cells, including natural killer (NK) cells. () bacterium has been explored in a large area of research fields, including the host pathogen interaction. Although the importance role of NK cells in controlling the first phase of burden has been investigated, the interaction between NK cells and infected cells in details are far from being comprehended. From and experiments, we can drive several important pieces of knowledge that hopefully contribute to illuminating the intercommunication between infected cells and NK cells. Experimental studies performed in rats revealed that certain NK cell ligands are influenced in infected cells. These ligands include both classical- and non-classical MHC class I molecules and C-type lectin related (Clr) molecules that are ligands for Ly49- and NKR-P1 receptors respectively. Interaction between these receptors:ligands during infection, demonstrated stimulation of rat NK cells. Hence, these studies provided additional knowledge to the mechanisms NK cells utilise to recognise and respond to infection outlined in the current review.
Topics: Rats; Animals; Listeria monocytogenes; Ligands; Killer Cells, Natural; Listeriosis; Histocompatibility Antigens Class I; Lectins, C-Type
PubMed: 37285590
DOI: 10.1177/17534259231178223 -
Journal of Infection and Public Health Dec 2023Contamination and transmission of different Listeria monocytogenes strains along food chain are a serious threat to public health and food safety. Understanding the...
BACKGROUND
Contamination and transmission of different Listeria monocytogenes strains along food chain are a serious threat to public health and food safety. Understanding the distribution of diseases in time and space-time is fundamental in the epidemiological study and in preventive medicine programs. The aim of this study is to estimate listeriosis incidence along 10-years period and to perform space-time cluster analysis of listeriosis cases in Marche Region, Italy.
METHODS
The number of observed listeriosis cases/year was derived from regional data of surveillance of notifiable diseases and hospital discharge form. The capture and recapture method (C-R method) was applied to estimate the real incidence of listeriosis cases in Marche Region and the space-time scan statistics analysis was performed to detect clusters of space-time of listeriosis cases and add precision to the conventional epidemiological analysis.
RESULTS
The C-R method estimation of listeriosis cases was 119 in the 10- year period (2010-2019), with an average of 31.93 % of unobserved cases (lost cases). The estimated mean annual incidence of listeriosis was 0.77 per 100,000 inhabitants (95 %CI 0.65-0.92), accounting for 6.07 % of additional listeriosis cases per year than observed cases. Using the scan statistic, the two most likely clusters were identified, one of these was statistically significant (p < 0.05). The underdiagnosis and under-reporting in addition to listeriosis incidence variability suggested that the surveillance system of Marche Region should be improved.
CONCLUSIONS
This study provides evidence of the ability of space-time cluster analysis to complement traditional surveillance of food-borne diseases and to understand the local risk factors by implementing timely targeted interventions.
Topics: Humans; Incidence; Listeriosis; Listeria monocytogenes; Foodborne Diseases; Italy; Food Microbiology
PubMed: 37866268
DOI: 10.1016/j.jiph.2023.10.008 -
Foods (Basel, Switzerland) Apr 2024A review of quantitative risk assessment (QRA) models of in produce was carried out, with the objective of appraising and contrasting the effectiveness of the control... (Review)
Review
A review of quantitative risk assessment (QRA) models of in produce was carried out, with the objective of appraising and contrasting the effectiveness of the control strategies placed along the food chains. Despite nine of the thirteen QRA models recovered being focused on fresh or RTE leafy greens, none of them represented important factors or sources of contamination in the primary production, such as the type of cultivation, water, fertilisers or irrigation method/practices. Cross-contamination at processing and during consumer's handling was modelled using transfer rates, which were shown to moderately drive the final risk of listeriosis, therefore highlighting the importance of accurately representing the transfer coefficient parameters. Many QRA models coincided in the fact that temperature fluctuations at retail or temperature abuse at home were key factors contributing to increasing the risk of listeriosis. In addition to a primary module that could help assess current on-farm practices and potential control measures, future QRA models for minimally processed produce should also contain a refined sanitisation module able to estimate the effectiveness of various sanitisers as a function of type, concentration and exposure time. Finally, growth in the products down the supply chain should be estimated by using realistic time-temperature trajectories, and validated microbial kinetic parameters, both of them currently available in the literature.
PubMed: 38611415
DOI: 10.3390/foods13071111 -
Journal of Food Protection Nov 2023Listeria monocytogenes (Lm) is a Gram-positive bacterium that causes invasive listeriosis, an illness with high mortality and hospitalization rates. Due to the severity...
Listeria monocytogenes (Lm) is a Gram-positive bacterium that causes invasive listeriosis, an illness with high mortality and hospitalization rates. Due to the severity of illness associated with Lm, rapid identification and characterization of isolates from foods and the food-processing environment are critical to properly identify and track the pathogen and quickly remove adulterated foods from the market. Prior methods can rely on time-consuming biochemical or sera-agglutination assays to perform these tasks. Development of a high-throughput method that would rapidly perform these tasks is critical to improve response to contamination events. Previously, a single laboratory validation of a qPCR-based method was presented that could rapidly verify Lm isolates and characterize them into six molecular serogroups. In the current study, a multi-laboratory validation (MLV) was performed to evaluate the reliability of the qPCR method for identification and serogrouping of Lm isolates. Sixteen collaborating laboratories independently analyzed a panel of 43 blinded isolates plus three control strains using the qPCR method. This panel was comprised of representatives for non-Listeria (n = 7), Listeria sp. (n = 8), and Lm (n = 28) strains. The Lm isolates contained representatives of the six serogroups: 2A, 2B, 2C, 4B, NT, and 4bV/IVb-v1, with five strains for each serogroup except 4bV/IVb-v1 (n = 3). The results generated by 16 laboratories showed high sensitivity, specificity, and accuracy, generally ≥97%, for both the genus-species and serogrouping qPCRs. Results from one laboratory lowered the sensitivity of the non-Listeria group to 93%. These results indicated the method was highly reliable. However, only the previously evaluated serogroups were tested within the MLV panel, though there is the potential for other serogroup results. Sequence Read Archive (SRA) files for Lm isolates were evaluated to determine the frequency of other potential serogroup profiles. This effort identified a low percentage of isolates with atypical qPCR serogroups (0.30%) that are consistent with Lm and were generally associated with lineage II and the natural environment. In summary, the results indicate that the proposed qPCR method is reliable and has a high degree of sensitivity, accuracy, and specificity, while also decreasing hands-on analysis time and increasing throughput of the analysis.
Topics: Humans; Listeria monocytogenes; Serotyping; Reproducibility of Results; Food Microbiology; Listeriosis; Serogroup
PubMed: 37806351
DOI: 10.1016/j.jfp.2023.100178 -
PeerJ 2023Kuth is an aromatic plant used for food seasoning food and in Mexican traditional medicine. Among, leaves properties, it has proven antibacterial activity which can be...
BACKGROUND
Kuth is an aromatic plant used for food seasoning food and in Mexican traditional medicine. Among, leaves properties, it has proven antibacterial activity which can be used against opportunistic pathogens like , a foodborne bacteria that is the causal agent of listeriosis, a disease that can be fatal in susceptible individuals. The aim of this work was to investigate the antibacterial activity of Kuth leaf extracts against and to identify its bioactive components.
MATERIAL AND METHODS
leaves were macerated with four solvents of different polarity (-hexane, dichloromethane, ethyl acetate, and methanol). To determine the capacity to inhibit bacterial proliferation , agar diffusion and microdilution methods were used. Next, we determined the minimal bactericidal concentration (MBC). Finally, we determined the ratio of MBC/MIC. Metabolites present in the active methanolic extract from Kuth (LgMeOH) were purified by normal-phase open column chromatography. The structure of the antibacterial metabolite was determined using nuclear magnetic resonance (H, C, COSY, HSQC) and by comparison with known compounds.
RESULTS
The LgMeOH extract was used to purify the compound responsible for the observed antimicrobial activity. This compound was identified as 5,7-dihydroxyflavanone (pinocembrin) by analysis of its spectroscopic data and comparison with those described. The MIC and MBC values obtained for pinocembrin were 0.68 mg/mL, and the ratio MBC/MIC for both LgMeOH and pinocembrin was one, which indicates bactericidal activity.
CONCLUSION
Kuth leaves and its metabolite pinocembrin can be used to treat listeriosis due the bactericidal activity against .
Topics: Humans; Listeria monocytogenes; Plant Extracts; Litsea; Microbial Sensitivity Tests; Anti-Bacterial Agents; Listeriosis; Methanol
PubMed: 38054017
DOI: 10.7717/peerj.16522 -
Microbiology Spectrum Sep 2023is a nuclear transcription factor, and its activity is tightly regulated by the level of available oxygen in cells. Here, we investigated the roles of in the invasion...
is a nuclear transcription factor, and its activity is tightly regulated by the level of available oxygen in cells. Here, we investigated the roles of in the invasion of into tilapia under hypoxic environments. We found that the expression levels of in examined tissues of hypoxic tilapia were significantly upregulated, indicating that the tissue cells have been in hypoxic conditions. After 24-h infection with , we found that bacterial burden counts increased significantly in all examined tissues of hypoxic fish. To explore why the bacterial count increased significantly in the tissues of hypoxic fish, we modulated expression through RNAi technology. The results indicated that expression levels were positively related to expression. Since c-Met is the receptor of InlB that plays critical roles in the adhesion and invasion of , the ∆ strain was used to further explore the reason for the significant increase in bacterial counts in hypoxic fish. As expected, the decrease in the adhesion ability of ∆ suggested that InlB mediates infection in tilapia. After being infected with ∆ strain, we found that the bacterial counts in hypoxic fish were not affected by hypoxic conditions or expression levels. These findings indicate that may promote the internalization of InlB by upregulating expression and therefore contributes to the invasion of into hypoxic tilapia. IMPORTANCE is a zoonotic food-borne bacterial pathogen with a solid pathogenicity for humans. After ingestion of highly contaminated food, is able to cross the intestine invading phagocytic and nonphagocytic cells and causes listeriosis. China is the world's largest supplier of tilapia. The contamination rate of to tilapia products was as high as 2.81%, causing a severe threat to public health. This study revealed the underlying regulatory mechanisms of in the invasion of into tilapia under hypoxic environments. This study will be helpful for better understanding the molecular mechanisms of hypoxic environments in infection to tilapia. More importantly, our data will provide novel insights into the prevention and control of this pathogen in aquaculture.
PubMed: 37681973
DOI: 10.1128/spectrum.01405-23 -
Biomedicine & Pharmacotherapy =... Feb 2024Listeria monocytogenes (Lm), a foodborne bacterium, can infect people and has a high fatality rate in immunocompromised individuals. Listeriolysin O (LLO), the primary... (Review)
Review
Listeria monocytogenes (Lm), a foodborne bacterium, can infect people and has a high fatality rate in immunocompromised individuals. Listeriolysin O (LLO), the primary virulence factor of Lm, is critical in regulating the pathogenicity of Lm. This review concludes that LLO may either directly or indirectly activate a number of host cell viral pathophysiology processes, such as apoptosis, pyroptosis, autophagy, necrosis and necroptosis. We describe the invasion of host cells by Lm and the subsequent removal of Lm by CD8 T cells and CD4 T cells upon receipt of the LLO epitopes from major histocompatibility complex class I (MHC-I) and major histocompatibility complex class II (MHC-II). The development of several LLO-based vaccines that make use of the pore-forming capabilities of LLO and the immune response of the host cells is then described. Finally, we conclude by outlining the several natural substances that have been shown to alter the three-dimensional conformation of LLO by binding to particular amino acid residues of LLO, which reduces LLO pathogenicity and may be a possible pharmacological treatment for Lm.
Topics: Humans; Bacterial Toxins; Listeriosis; CD8-Positive T-Lymphocytes; Immunity; Listeria monocytogenes; Heat-Shock Proteins; Hemolysin Proteins
PubMed: 38194738
DOI: 10.1016/j.biopha.2024.116129 -
BMC Microbiology Jun 2023Raw milk may contain pathogenic microorganism that can sometimes fatally affect the health of consumers. However, risks related to raw milk consumption in Southwest...
BACKGROUND
Raw milk may contain pathogenic microorganism that can sometimes fatally affect the health of consumers. However, risks related to raw milk consumption in Southwest Ethiopia are not well studied. The aim of this study was to evaluate the presence of five target pathogenic bacteria including Escherichia coli O157:H7, Salmonella enterica Typhimurium, Staphylococcus aureus, Listeria monocytogenes, and Campylobacter jejuni in raw milk and to assess exposure associated with the consumption of raw milk.
METHOD
A cross-sectional study was carried out between November 2019 and June 2020 to in Jimma zone, Southwest Ethiopia. Laboratory analysis was conducted on milk samples collected from Seven Woreda towns, including, Agaro, Yebu, Sekoru, Serbo, Shebe, Seka, Sheki and Jimma town administration. Semi-structured interview questions were administered to collect data on the amount and frequency of consumption. Descriptive statistics were used to summarize laboratory results and questionnaire survey data.
RESULT
Among 150 total raw milk samples, about 61.3% were found contaminated by one or more types of pathogens along the dairy value chain. The highest and the least bacterial counts recorded were 4.88 logcfu/ml and 3.45 logcfu/ml from E. coli and L. monocytogenes respectively. The mean concentrations of pathogens demonstrated significant statistical difference (p < 0.05) using 95% confidence interval where the prevalence percentage of isolates increased as the milk was transported from farms to the retail outlets. Except for C. jejuni; all other pathogens were detected in the range of unsatisfactory level of milk microbiological quality along the chain. The estimated mean annual risk of acquiring intoxication of E. coli across retailer outlets is 100% whereas salmonellosis, S. aureus intoxication, and listeriosis are 84%, 65% and 63% respectively.
CONCLUSION
The study highlights the significant health risks associated with the consumption of raw milk due to its unacceptable microbiological quality. The traditional production and consumption patterns of raw milk are the primary reasons for the high annual probability of infection. Therefore, regular monitoring and implementation of hazard identification and critical control point principles are necessary from raw milk production to retail points to ensure the safety of consumers.
Topics: Animals; Milk; Cross-Sectional Studies; Ethiopia; Staphylococcus aureus; Escherichia coli O157
PubMed: 37312070
DOI: 10.1186/s12866-023-02910-0