Which part of the intestine is affected by salmonella?

Salmonella Primarily Affects the Ileum and Colon

Salmonella primarily affects the ileum (small intestine) and colon, with colonic involvement being particularly common and important in causing diarrhea. 1, 2

Pathophysiology of Intestinal Involvement

• Salmonella typically enters the body through contaminated food or water and initially invades the intestinal epithelium of the small intestine, particularly the ileum 3
• After invasion, Salmonella can either remain localized in the intestinal mucosa causing gastroenteritis or translocate across the mucosa leading to systemic infection 4
• Colonic involvement is extremely common in human salmonellosis and plays a crucial role in the development of diarrhea symptoms 1
• In typhoid fever, which is caused by specific Salmonella serotypes (S. Typhi and S. Paratyphi), perforations typically occur in the ileum or jejunum 2

Clinical Manifestations of Intestinal Involvement

• Salmonella infection presents with three major clinical syndromes 2, 5:

  1. Self-limited gastroenteritis
  2. More severe prolonged diarrheal disease with fever and bloody diarrhea
  3. Septicemia with potential extraintestinal involvement

• Bloody diarrhea can occur with Salmonella infection, indicating significant colonic inflammation 2

• Symptoms typically include abdominal pain, fever, and diarrhea due to the inflammatory response in the affected intestinal segments 6

Diagnostic Considerations

• Diagnosis of Salmonella infection is established through stool cultures and blood cultures 2
• Due to the high rate of bacteremia in immunocompromised patients, blood cultures should be obtained from any patient with diarrhea and fever 2
• Endoscopy may reveal ulcerations in the colon similar to those seen with other forms of colitis 2
• Sigmoidoscopic examination and biopsy in patients with acute Salmonella infection commonly reveal active colitis 1

Risk Factors for Severe Disease

• The risk for more severe intestinal disease increases with the degree of immunosuppression 2, 5
• HIV-infected individuals have 20-100 times higher risk of Salmonella infection with increased likelihood of bacteremia and extraintestinal spread 5
• Relapses in Salmonella infections after appropriate treatment are well-documented, particularly in immunocompromised patients 2, 5

Prevention and Management

• Scrupulous handwashing can reduce the risk of Salmonella infection 2, 5
• Avoid consumption of raw or undercooked eggs, poultry, meat, and seafood 2
• Unpasteurized dairy products and fruit juices should also be avoided 2
• Fluid and electrolyte replacement is the cornerstone of management for Salmonella gastroenteritis 6
• Antimotility drugs should be avoided in cases of inflammatory diarrhea or diarrhea with fever, which is common with Salmonella infection 6

Special Considerations

• In typhoid fever, which is caused by specific Salmonella serotypes, intestinal perforation typically occurs in the third week of disease 2
• Bacterial flagellins from Salmonella can directly activate signaling pathways in intestinal epithelial cells, triggering inflammation 2
• Impaired epithelial signaling through the flagellin/TLR pathway can result in an abnormal immune response and severe chronic inflammation 2

Understanding the intestinal tropism of Salmonella is crucial for proper diagnosis, management, and prevention of complications in affected individuals.