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At least 811 records · Page 45Linked to original sources
PubMed2003

Enteric salmonella infection inhibits Paneth cell antimicrobial peptide expression.

Paneth cells, highly secretory epithelial cells found at the bases of small intestinal crypts, release a variety of microbicidal molecules, including alpha-defensins and lysozyme. The secretion of antimicrobials by Paneth cells is thought to be important in mucosal host defense against invasion by enteric pathogens. We explored whether enteric pathogens can interfere with this arm of defense. We found that oral inoculation of mice with wild-type Salmonella enterica serovar Typhimurium decreases the expression of alpha-defensins (called cryptdins in mice) and lysozyme. Oral inoculation with Salmonella serovar Typhimurium strains that are heat killed, lack the PhoP regulon, and lack the SPI1 type III secretion system or with Listeria monocytogenes does not have this effect. Salmonella may gain a specific survival advantage in the intestinal lumen by decreasing the expression of microbicidal peptides in Paneth cells through direct interactions between Salmonella and the small intestinal epithelium.

Animals↗
PubMed1979

Mucosal defenses against Salmonella infection in the mouse.

Specific pathogen-free ICR (Institute of Cancer Research) mice were challenged with Salmonella orally, aerogenically, or parentally 24 hr after they received sublethal whole-body irradiation. The early growth for the sublethal inoculum was identical in irradiated and control mice. In the irradiated group, Salmonella multiplied in the liver and spleen until death of the host. Increasing the dose of irradiation reduced the size of the mean lethal dose for the intravenous, intraperitoneal, and aerogenic challenges. However, in the orally challenged mice, the 50% lethal dose dropped only 100-fold when the radiation was increased from 0 to 400 rad, with little further decrease even when the dose was increased to 800 rad. Presumably, the local gut defenses were responsible for this considerable disparity in the lethal effects of an oral vs. parenteral challenge. No evidence was found for enhanced local infection of the gut or increased involvement of the gut-associated lymphoid organs in the irradiated host. The increased mortality seen in the irradiated group seemed to be associated with a continued unrestricted growth of Salmonella in the liver and spleen when the number of peripheral blood leukocytes was at a minimum. Resistance to the sublethal salmonella challenge was eventually restored as the total counts of white blood cells returned to normal.

Administration, Oral↗
PubMed1975

Transport in bacteriophage P22-infected Salmonella typhimurium.

There was rapid efflux of L-leucine, L-phenylalanine, and alpha-methyl-D-glucoside after infection of Salmonella typhimurium with the clear plaque mutant C1 of phage P22. The efflux was similar to that observed with cyanide or arsenate treatment except that there was partial recovery in the case of phage infection and almost complete recovery under the condition of lysogeny. There was no efflux after infection with the temperature-sensitive mutant ts16C1 at nonpermissive temperature. Superinfection of superinfection exclusion negative lysogen (sie A minus sie B minus) with C1 led to efflux, whereas the efflux was much less on superinfection of sie A+ Sie B+ lysogen. These results indicate that an effective injection process is enough to cause depression in the cellular transport processes.

Arsenates↗
PubMed1997

An international outbreak of Salmonella infections caused by alfalfa sprouts grown from contaminated seeds.

An outbreak of Salmonella serotype stanley infections occurred in the United States and Finland in 1995. The outbreak was investigated through case-control studies in Arizona, Michigan, and Finland; by isolate subtyping; and by tracing and culturing of the implicated food. Alfalfa sprout consumption was the only exposure associated with S. stanley infections in Arizona (matched odds ratio [MOR] = 11.1; 95% confidence interval [CI], 1.4-513), Michigan (MOR = 5.5; CI, 1.6-23), and Finland (MOR undefined; CI, 4.9-infinity). US and Finnish patient isolates were a unique outbreak strain distinct from S. stanley isolates not linked to the outbreak. Alfalfa sprouts eaten by patients in 6 US states and Finland were traced to seed shipped by a Dutch shipper. Thus, it was concluded that alfalfa sprouts grown from contaminated seed caused an international outbreak of > or =242 S. stanley infections in > or =17 US states and Finland. This outbreak illustrates a new mechanism through which contamination of fresh produce can cause large, widely dispersed outbreaks.

Adolescent↗
PubMed1994

Secretory immune response and clinical sequelae of Salmonella infection in a point source cohort.

OBJECTIVE: To determine the kinetic isotypic serum and secretory immune response to Salmonella enteritidis in a cohort of individuals exposed to the organism in a single food source outbreak of dysentery. To determine the clinical outcome and immunogenetics of the exposed cohort and to correlate these features with the immune response. METHODS: Following a single point source outbreak of Salmonella enteritidis, a cohort of dysenteric individuals were ascertained using a reactive arthritis screening questionnaire (QUEST). Serum and stimulated saliva samples were obtained at 6, 12, and 24 months following the outbreak of dysentery; examinations were conducted at the same time. Two unexposed control groups were ascertained: (1) general rheumatology clinic patients and (2) well nonarthritic family practice patients. An ELISA to determine quantitative IgA responses to Salmonella enteritidis lipopolysaccharide (LPS) was performed. RESULTS: Eleven of the 84 exposed individuals with dysentery developed reactive arthritis (ReA) of reactive enthesitis (ReE). There was a prolonged salivary IgA anti-LPS response in both the ReA/ReE and DYS (dysentery alone) patients compared with unexposed controls. A ratio of salivary IgA anti-LPS/serum IgA anti-LPS > 1 was associated with a good outcome (remission) of ReA, whereas a ratio < 1 was associated with chronic disease. CONCLUSIONS: There is a more prolonged humoral immune response to Salmonella LPS in exposed individuals than hitherto described. A risk factor in the prolongation of ReA is the inability to mount an appropriate specific salivary (secretory) immune response.

Adolescent↗