Quantifying Translocation ofListeria monocytogenesin Rats by Using Urinary Nitric Oxide-Derived Metabolites

Abstract

The urinary nitric oxide metabolites NO 2 ؊ and NO 3 ؊ (summed as NO x ) are a noninvasive, quantitative biomarker of translocation of salmonella from the intestinal lumen to systemic organs. Listeria monocytogenes is a food-borne gram-positive pathogen that can also cross the intestinal epithelium. In this study, we tested the efficacy of urinary NO x as a marker of listeria translocation. Rats (eight per group) were orally infected with increasing doses of L. monocytogenes; control rats received heat-killed listeria. The kinetics of urinary NO x and population levels of listeria in feces were determined for 7 days. Another group of rats was killed 1 day after infection to verify translocation by culturing viable listeria from systemic organs. Oral administration of increasing doses of L. monocytogenes resulted in a time-and dose-dependent increase in urinary NO x excretion. Translocation was a prerequisite for inducing a NO x response, since heat-killed L. monocytogenes did not elevate NO x excretion in urine. Fecal counts of listeria also showed dose and time dependency. Moreover, the number of viable L. monocytogenes cells in mesenteric lymph nodes also increased in a dose-dependent manner and correlated with urinary NO x . In conclusion, urinary NO x is a quantitative, noninvasive biomarker of listeria translocation.Listeria monocytogenes is a food-borne gram-positive pathogen that is able to translocate across the gut epithelium, resulting in listeriosis, i.e., systemic infection. Most healthy adults experience a limited infection, with at most mild influenza-like symptoms or, in some cases, gastroenteritis (2, 13, 30). However, listeriosis is extremely dangerous for pregnant women, causing abortions and stillbirths, and for newborn, elderly, and immunocompromised individuals, causing meningitis, meningoencephalitis, or sepsis (13,14,18,21,30). In Europe, the incidence of listeriosis is increasing (2, 14). The rate of mortality caused by listeriosis, excluding abortions, is one of the highest among bacterial infections. Overall fatality rates of 24 to 44% have been reported (2,14,18,21). Because of the property of pathogens to acquire resistance to antibiotics, new approaches to prevent listeriosis deserve attention. Luminal factors such as gastric acidity, antimicrobial bile salts and fatty acids, and pancreatic enzymes contribute to the intestinal nonspecific defenses by killing pathogens. Therefore, changing the composition of the diet and thus changing the composition of gastrointestinal contents may affect colonization and translocation of L. monocytogenes. To study the efficacy of food components, an animal model of food-derived listeriosis with a quantitative, reliable, and accurate biomarker for translocation is required. Translocation of L. monocytogenes is observed in rats (24, 28) and mice (26), making them suitable models. Classically, translocation of listeria in animal models is determined by microbiological culturing of lymphoid organs (24,26,28). This approach has some disadvantages. First,...

Dietary fructo-oligosaccharides and inulin decrease resistance of rats to salmonella: protective role of calcium

“…Urinary NO x is a sensitive and quantitative biomarker of intestinal bacterial translocation 28 which correlates with organ cultures 29 and severity of systemic infectious diseases in rats and humans. [30][31][32] The increased colonisation and translocation of salmonella in the present study, concomitant with decreased animal growth after infection, indicates that the infection was worse in the low calcium/inulin and FOS groups. These data confirm the results of our previous studies in which FOS increased translocation of salmonella.…”

Comparative characterization of oxide-dependent and nitroxide-forming enzymatic systems of macrophages under staphylococcus aureus and listeria monocytogenes infections

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