Listeria monocytogenes is a facultative intracellular bacterium that causes foodborne disease in humans. L. monocytogenes invade the gut mucosa and then disseminate, causing systemic infections associated with high mortality rates in immunocompromised individuals. It is unknown how L. monocytogenes traffic to the mesenteric lymph nodes, which represent an important bottleneck for systemic spread. In addition, little is known about the gastrointestinal stage of infection due to the general resistance of mice to oral infection with L. monocytogenes. Our laboratory developed a novel foodborne mouse model of listeriosis utilizing a murinized strain of L. monocytogenes to investigate the gastrointestinal stage of infection. First, we found that the majority of L. monocytogenes isolated from the intestinal tissue and MLN were extracellular; however, the minimal fraction of intracellular L. monocytogenes was vital for persistence in the gut and spread to the MLN. The vast majority of cell-associated L. monocytogenes in the MLN were adhered to inflammatory monocytes, but these cells did not support the intracellular growth of L. monocytogenes. A minor proportion of L. monocytogenes were associated with migratory dendritic cells in the intestinal lamina propria and MLN, but like monocytes, these cells did not appear to serve as an intracellular growth niche for L. monocytogenes. Lastly, extracellular L. monocytogenes were observed migrating in mesenteric lymphatic vessels that drain from the intestine to the MLN, suggesting that L. monocytogenes can spread beyond the intestinal mucosa independent of migratory immune cells. Overall, these studies are the first to characterize the interaction of L. monocytogenes with immune cells in the intestine and MLN following foodborne infection and suggest that extracellular, and not cytosolic L. monocytogenes, primarily drive innate immune responses in the gut.

Foodborne diseases form a large group of infectious diseases. These substantial diseases are occurring more in developing countries but they do not avoid developed countries. The originators of the disease are bacteria and their toxins, viruses, parasites and prions, whose source is an infected person or animal. The disease is passed on by contaminated soil, contaminated water and food, sometimes contaminated items. Greatest importance in the prevention of foodborne disease are nonspecific measures, protection of drinking water, safe food production, waste disposal, functional sewer system, rodenticides and insecticides measures and of course the principles of personal hygiene, certain standards of hygiene and health education of the population. Intestinal infections are preventable. The consumer can effectively protect by following the fundamental principles established by the World Health Organization. The aim of this study was to explore knowledge of foodborne disease prevention measures and compliance with these principles by adolescents in the Milevsko region. The theoretical part of the study summarizes the basic information about intestinal diseases and describes their effect on health from a variety of perspectives. The preventive measures which everyone should be aware of and apply them in everyday life to protect health are described in great detail. The paper summarizes the information about the process of spreading foodborne diseases and epidemiological measures focused on supply, routes of transmission and susceptible individuals. The theoretical part includes basic information about specific intestinal infections which are most significant for the population in the Czech Republic. Briefly described are treatment of these diseases and the most important legislative measures. In the research part quantitative research was applied by questionnaire. The research groups were students of higher secondary vocational schools and vocational schools in the region Milevsko. Three hypotheses were formulated. Statistical hypothesis testing was performed using the t test. The values of the achieved significance level are compared with a predetermined level of significance. The first hypothesis assumed that knowledge about prevention of intestinal diseases is higher among girls than boys. This statement has not been confirmed. Knowledge of the principles of prevention does not differ according to the criteria of gender. Two further hypotheses assumed that the observance of hygienic measures in the prevention of foodborne disease is higher among girls than among boys and higher for high-school graduates than apprentices. These hypotheses are valid. Precautionary principles are indeed respected more by girls than boys and high-school graduates than apprentices. The carried out research shows that adolescents in the region Milevsko have a good knowledge of foodborne infections and do known also essential preventive measures. However, knowledge of these rules does not mean they are applied in practice. The results showed that some rules, such as washing fruits and vegetables before eating, adequate boiling or roasting of food, especially hand hygiene before eating food or after contact with an animal are observed by a smaller percentage of respondents than that reported knowledge of these principles. A positive finding is that respondents comply with certain rules, without being aware of them, such as the principle of proper preservation of precooked food. Foodborne diseases are diseases which can be prevented in compliance with precautionary principles. Especially in the Czech Republic, where nonspecific principles are at a high level. It is up to each user/consumer how consistent these principles will be. Respecting preventive measures is a prerequisite for reducing the incidence of foodborne disease in the population.

<p>The crossing of host barriers (intestinal, blood-brain, and placental) is a critical step for systemic infections caused by entero-invasive pathogens. In the intestine, the epithelial cells are the first line of defense against enteric pathogens. <i>Listeria monocytogenes</i> is a facultative-intracellular foodborne pathogen that first crosses the intestinal barrier to cause a systemic infection. However, the underlying mechanism is not well understood.</p><p><br></p> <p>We demonstrate that <i>Listeria</i> adhesion protein (LAP) promotes the translocation of <i>L. monocytogenes </i>across the intestinal barrier in mouse models (A/J and C57BL/6). Relative to the wild-type (WT; serotype 4b) or the isogenic bacterial invasion protein Internalin A mutant (Δ<i>inlA</i>) strain, the <i>lap^─</i> strain showed significant defect in translocation across the intestinal barrier and colonization of the mesenteric-lymph nodes, liver and spleen in the early phase of infection (24 h and 48 h). LAP induces intestinal epithelial barrier dysfunction for increased translocation as evidenced by increased permeability to 4-kDa FITC-dextran (FD4), a marker of paracellular permeability, in the serum and urine of WT and Δ<i>inlA</i>- infected mice and across Caco-2 cell barrier, but not the <i>lap^─</i> mutant strain. Microscopic examination confirmed localization of the WT and Δ<i>inlA</i> strains in the tight junction, a crucial barrier of intestinal paracellular permeability, in the mouse ileal tissue but the <i>lap^─</i> strain remained confined in the lumen. LAP also upregulates TNF-α and IL-6 in intestinal epithelia of mice and in Caco-2 cells for increased permeability. </p><p><br></p> <p>Investigation of the underlying molecular mechanisms of LAP-mediated increase in intestinal permeability by using <i>lap^─</i> mutant strain, purified LAP and shRNA-mediated Hsp60 suppression, we demonstrate that LAP interacts with its host receptor, Hsp60, and activates the canonical NF-κB signaling, which in turn facilitates myosin light-chain kinase (MLCK)-mediated opening of the epithelial barrier via the cellular redistribution of major epithelial junctional proteins claudin-1, occludin, and E-cadherin. Pharmacological inhibition of NF-κB or MLCK in cells or genetic ablation of MLCK in mice (C57BL/6) prevents mislocalization of epithelial junctional proteins, intestinal permeability and <i>L. monocytogenes</i> translocation across the intestinal barrier.</p> <p><br></p><p>Furthermore, LAP also promotes <i>L. monocytogenes </i>translocation across the intestinal barrier and systemic dissemination in a Mongolian gerbil that are permissive to the bacterial invasion proteins; InlA-and InlB-mediated pathways; similar to that in humans. We show a direct LAP-dependent and InlA-independent pathway<i> </i>for <i>L. monocytogenes</i> paracellular translocation across the intestinal epithelial cells that do not express luminally accessible E-cadherin. Additionally, we show a functional InlA/E-cadherin interaction pathway that aids <i>L. monocytogenes</i> translocation by targeting cells with luminally accessible E-cadherin such as cells at the site of epithelial cell extrusion, epithelial folds and mucus-expelling goblet cells. Thus, <i>L. monocytogenes</i> uses LAP to exploit epithelial innate defense in the early phase of infection to cross the intestinal epithelial barrier, independent of other invasion proteins.</p><p><br></p> <p>This work fills a critical gap in our understanding of <i>L. monocytogenes </i>pathogenesis and sheds light to the complex interplay between host-pathogen interactions for bacterial crossing of the crucial intestinal barrier.</p> <br>