Small Intestine, Infectious Diseases

• • Infection leads to acute enteritis (acute inflammation of the small intestine) and mesenteric lymphadenitis (inflammation of regional small intestinal lymph nodes)

  • Small intestinal infections often mimic surgical conditions of the abdomen such as acute appendicitis

  • May also cause complications (such as perforation or bleeding) that require surgical intervention

Epidemiology

• • HIV-associated enteropathy

  • -Associated with opportunistic GI infections

    -Intestinal perforation is a known complication

  • Yersinia enteritis: Associated withacute gastroenteritis, terminal ileitis, mesenteric lymphadenitis, hepatic and splenic abscesses

  • Campylobacter jejuni: Raw milk, untreated drinking water, and undercooked poultry are recognized vehicles of transmission

  • TB

  • -Most infections due to swallowing the human tubercle bacillus

    -About 1% of patients with pulmonary TB have intestinal involvement

    -Recent immigration from endemic areas and infection with HIV are risk factors

    -Often affects the distal ileum

  • Salmonella typhi: May cause ulcers in the distal ileum or cecum

Symptoms and Signs

• • Fever

  • Diarrhea

  • Chronic or relapsing bloody diarrhea in severe cases

  • Nausea and vomiting

  • Abdominal pain

  • Abdominal tenderness

Laboratory Findings

• • Elevated WBC count with eosinophilia

  • Culture of stool or tissue obtained by biopsy may allow isolation and identification of the pathogen

  • Organisms may be visualized by microscopic exam of stool or biopsy specimens

Imaging Findings

• • Plain film radiography or CT scan:

  • -Findings are nonspecific

    -Intestinal dilation, bowel wall thickening, and fat stranding in the mesentery may be observed

  • Endoscopy: May reveal mucosal lesions, inflammation, and ulcerations and allow biopsy for potential isolation and identification of the infectious pathogen

• • Pathogens associated with HIV-Associated enteropathy include:

  • -Cryptosporidium

    -Cytomegalovirus

    -Entamoeba histolytica

    -Giardia lamblia

    -Mycobacterium avium-intracellulare

    -Salmonella typhimurium

    -Shigella

    -Campylobacter jejuni

    -HIV

  • Tuberculosis: The pathologic reaction is hypertrophic (causing stenosis and obstruction) or ulcerative (causing abdominal pain, diarrhea, free perforation, fistula formation, or hemorrhage)

Rule Out

• • Noninfectious causes of GI inflammation (pancreatitis, appendicitis)

• • CBC

  • Stool for culture

  • Plain film or CT scan of the abdomen

  • Endoscopy for exam and biopsy

When to Admit

• • Perforation

  • Obstruction

  • Severe bleeding

  • Dehydration

Surgery

• • If operation is performed for a diagnosis of appendicitis and the entire distal small bowel is grossly inflamed, appendectomy is usually performed

  • Resection is indicated for complications

Indications

• • Perforation

  • Obstruction

  • Bleeding

  • Uncertain diagnosis

Medications

• • Many of these infections are self-limited and require no specific treatment

  • Antimicrobial treatment should be aimed at the suspected or confirmed pathogen

Complications

• • Perforation

  • Hemorrhage

Prognosis