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What causes salmonellosis in adults?
Medical expert of the article
Last reviewed: 04.07.2025
Causes of salmonellosis
The cause of salmonellosis is salmonella - gram-negative rods of the genus Salmonella of the Enterobacteriaceae family. There are two types of salmonella - S. enterica and S. bongori. not pathogenic for humans. There are 2324 serovars, divided by a set of somatic O-antigens into 46 serogroups. In addition to the somatic thermostable O-antigen, salmonella have a flagellar thermolabile H-antigen. Many strains have a surface Vi-antigen. The main pathogenicity factors are cholera-like enterotoxin and lipopolysaccharide endotoxin. Some strains of S. enteritidis are capable of invading the epithelium of the large intestine. Salmonella persist in the environment for a long time: in water - up to 5 months, in soil - up to 18 months, in meat - up to 6 months. in bird carcasses - more than a year, on eggshells - up to 24 days. They tolerate low temperatures well, at 100 °C they die instantly.
[ Pathogenesis of salmonellosis
In the lumen of the small intestine, salmonella attach to the membranes of enterocytes and reach the lamina propria of the mucous membrane. This leads to degenerative changes in enterocytes and the development of enteritis. In the lamina propria, macrophages absorb salmonella, but phagocytosis is incomplete and generalization of the infection is possible. When bacteria are destroyed, a lipopolysaccharide complex (endotoxin) is released, which plays a major role in the development of intoxication syndrome. In addition, it activates the synthesis of prostanoids (thromboxanes, prostaglandins), which trigger platelet aggregation in small capillaries. Prostaglandins stimulate the secretion of electrolytes and fluid into the intestinal lumen, cause contraction of smooth muscles and increase peristalsis. The main role in the development of diarrhea and dehydration is played by enterotoxin, which activates the synthesis of cAMP by adenylate cyclase of enterocytes, due to which the secretion of Na+, CL- ions and water into the intestinal lumen increases. The consequence of dehydration and intoxication is a disruption of the cardiovascular system, which is expressed by tachycardia and a decrease in blood pressure.