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What causes salmonellosis in adults?
Medical expert of the article
Last reviewed: 23.04.2024
Causes of salmonellosis
The cause of salmonella - salmonella - Gram-negative rods of the genus Salmonella family Enterobacteriaceae. There are two types of salmonella - S. Enterica and S. Bongori. Not pathogenic to humans. There are 2324 serovars, divided by a set of somatic O-antigens into 46 serogroups. In addition to somatic thermostable O-antigen, salmonella have flagellum thermolabile H-antigen. In many strains, surface Vi-antigen is detected. The main pathogenicity factors are cholera-like enterotoxin and endotoxin of lipopolysaccharide nature. Some strains of S. Enteritidis are capable of invading the colon epithelium. Salmonella persists in the environment for a long time: in water - up to 5 months, in the soil - up to 18 months, in meat - up to 6 months. In carcasses of birds - more than a year, on the eggshell - up to 24 days. The low temperature is tolerated well, at 100 ° C perish instantly.
[Pathogenesis of salmonellosis
In the lumen of the small intestine, salmonella attach to the membranes of enterocytes, reaching their own plate of the mucous membrane. This leads to degenerative changes in enterocytes and the development of enteritis. In its own plate of mucous macrophages absorb salmonella, however phagocytosis is incomplete and generalization of 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). Triggering the aggregation of platelets in small capillaries. Prostaglandins stimulate the secretion of electrolytes and fluid in the lumen of the intestine, cause a reduction in smooth muscle 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, which increases the secretion of Na +, CL- and water ions into the lumen of the intestine. The consequence of dehydration and intoxication is a violation of the cardiovascular system, which is manifested by tachycardia and a decrease in blood pressure.