Diagnosis

Gastroenteritis

Etiology

Cause

• Infectious cause [bsg][4ws]

  • Viral (50-70%): Norovirus, rotavirus, adenovirus, astrovirus, coronavirus, calicivirus and small round-structured viruses (Norwalk, Southhampton and Lonsdale viruses).

  • Bacterial (15-20%): some pathogens may produce cytotoxin or invade the bowel wall causing inflammatory diarrhea

    Salmonella, Campylobacter, Escherichia coli, Listeria monocytogenes, Cholera, Shigella staphylococcus, streptococcus, Vibrio, Yersinia enterocolitica and Clostridium difficile.

  • Parasite (10-15%): Giardia lamblia, Entamoeba histolytica, Cryptosporidium. Isospora, Cyclospora, Microsporidium.

• Medications: Antibiotics, Laxative abuse, Sorbitol, Colchicine, Cardiac antidysrhythmics, NSAIDs, Chemotherapeutics, Antacids

• Toxic: Organophosphates, Poisonous mushrooms, Arsenic, Ciguatera or scombroid

• Inflammation: Celiac disease, Crohns disease, ulcerative colitis, ischemic colitis, toxin, alcohol, AIDS, radiation

• Complications: Reactive arthritis, Guillain-Barre syndrome and Hemolytic uremic syndrome.

Pathophysiology

1. Exposure typically occurs through the fecal-oral route

2. Cytotoxins effects on the enterocytes --> damage to the intestinal villi and enterocytes

   • Malabsorption

   • Osmotic diarrhea

   • Transudative fluid loss into the intestine

Risk factors

• Contaminated water (well)

• Contaminated food

• Undercooked food (seafood)

• Travel

• Immunsuppresion

• Poor sanitation

Epidemiology

Incidence per 100.000 [mua][zmv][pwi][fiy][wzm]

Approach

• Blood test: complete blood cell count, electrolytes, renal function, culture

• ELISA: Rotavirus, Giardia

• Stool:

  • Culture

  • Occult blood

  • Fecal leukocytes --> bacterial cause

  • Fecal lactoferrin (marker for fecal leukocytes) --> inflammatory process

  • C difficile assay

  • Stool ova and parasites

• CT abdomen

Treatment

1. Fluid replacement is the mainstay of symptomatic treatment: [zcd]

   • Oral rehydration is ideal

   • Intravenous hydration may be necessary in the setting of dehydration:

   • 1-2 L dextrose 5% in 0.5 isotonic sodium chloride solution with 50 mEq NaHCO3 and 10-20 mEq KCl over 30-45 minutes

2. Antiemetics: Ondansetron, Promethazine

3. Antimotility agents: should be avoided in cases of fever or rectal bleeding

   • Loperamide

   • Diphenoxylate

4. Bacterial infection/travellers diarrhea:

   • Ciprofloxacin (500 mg as a single dose or twice a day for 1–2 days)

   • Azithromycin (single 1-g dose), in children: 10 mg/kg as a single dose, not to exceed 1 g

   • Rifaximin (200 mg 3 times a day)

5. Lactobacillus GG, a specific probiotic

Prevention [bsg]

• Vaccines: Rotavirus

• Water must be boiled for 3 minutes to kill pathogens. Two drops of bleach or 5 drops of iodine kill pathogens in water within 30 minutes.

• Freezing does not kill pathogens. Avoid ice, request bottled beverages, and use a straw versus a glass.

• Fruit that must be peeled is safe. Fruit that is not peeled or raw vegetables should be avoided.

• Steam table buffets pose a high risk of contracting traveler’s gastroenteritis.

• Communal condiments are frequently contaminated and should be avoided.

• H2 blockers and proton pump inhibitors, can increase susceptibility to traveler’s diarrhea

Differential diagnoses

Appendicitis, Carcinoid tumor, Celiac disease, Cholecystitis, Clostridium difficile, Crohn disease, Diabetes mellitus, Diabetic ketoacidosis, Diverticulitis, Drug side effects, Gastrointestinal obstruction, Giardiasis, Hemolytic uremic syndrome, Ischemic colitis, Pancreatic failure, Pseudomembranous colitis, Salmonellosis, Sepsis, Shigellosis, Shock, Short bowel syndrome, Toxic megacolon, Ulcerative colitis, Urinary tract infection, Volvulus, Whipple's disease