Management of Infectious Diarrhea
The critical initial treatment for infectious diarrhea must include rehydration, which can be accomplished with an oral glucose or starch-containing electrolyte solution in the vast majority of cases. 1
Initial Assessment and Classification
Clinical Evaluation
- Assess for:
- Stool characteristics (watery, bloody, mucous, purulent, greasy)
- Frequency and quantity of bowel movements
- Presence of dysenteric symptoms (fever, tenesmus, blood/pus in stool)
- Signs of dehydration (thirst, tachycardia, orthostasis, decreased urination, lethargy, decreased skin turgor)
- Associated symptoms (nausea, vomiting, abdominal pain, cramps, headache, myalgias)
Epidemiological Risk Factors
- Travel to developing areas
- Day-care center attendance or employment
- Consumption of unsafe foods (raw meats, eggs, shellfish, unpasteurized products)
- Swimming in or drinking untreated surface water
- Contact with farm animals, reptiles, or pets with diarrhea
- Knowledge of other ill persons
- Recent medications (antibiotics, antacids, anti-motility agents)
- Underlying medical conditions (immunosuppression, prior gastrectomy)
- Sexual practices (where appropriate)
- Occupation as food-handler or caregiver
Management Algorithm
1. Rehydration (First Priority)
- Oral Rehydration Therapy (ORT) for mild to moderate dehydration:
- Use WHO-recommended oral rehydration solutions (ORS) containing appropriate electrolyte concentrations
- Commercial solutions like Ceralyte or Pedialyte
- Can be prepared by mixing 3.5g NaCl, 2.5g NaHCO₃, 1.5g KCl, and 20g glucose per liter of clean water 1
- Administer 10 ml/kg for each liquid stool and 2 ml/kg for each episode of vomiting
- Intravenous Fluids for severe dehydration until pulse, perfusion, and mental status normalize
2. Nutritional Management
- Continue feeding during episodes of diarrhea
- Resume age-appropriate diet during or immediately after rehydration
- Offer food every 3-4 hours
- Avoid foods high in simple sugars and fats
- For infants: maintain breastfeeding; for formula-fed infants, full-strength formulas can be safely reintroduced after rehydration
3. Diagnostic Testing (Selective Approach)
Perform stool studies for:
- Profuse, dehydrating diarrhea
- Febrile or bloody diarrhea
- Diarrhea lasting >1 day
- Immunocompromised patients
- Hospitalized patients
- Severe illness or systemic symptoms
4. Antimicrobial Therapy
- Not recommended for most adults with mild, watery diarrhea
- Consider antibiotics for:
- Shigellosis: Azithromycin (first-line) or TMP-SMX if susceptible
- Campylobacteriosis: Azithromycin (first-line) or Erythromycin
- Enterotoxigenic E. coli: TMP-SMX (if susceptible) or Azithromycin
- C. difficile: Oral vancomycin 125mg four times daily for 10 days 2
- Patients >65 years, immunocompromised, severely ill, or septic
5. Antimotility Agents
- May be considered in adults with non-bloody diarrhea after adequate hydration
- Contraindicated in children <18 years, bloody diarrhea, fever, or suspected inflammatory diarrhea 3
- Loperamide (for adults): Initial dose 4mg followed by 2mg every 4 hours, not exceeding 16mg/day
6. Infection Control Measures
- Hand washing with soap and water after using toilet, changing diapers, before preparing food
- Contact precautions with gloves and gowns for C. difficile
- Appropriate vaccination (e.g., rotavirus) for prevention
Special Considerations
Immunocompromised Patients
- Lower threshold for diagnostic testing and antibiotic treatment
- More aggressive hydration and monitoring
- Consider broader antimicrobial coverage
Severe Cases
- Monitor hydration status through weight changes, laboratory results, urine output
- Consider hospitalization for severe dehydration, systemic illness, or inability to maintain oral intake
- For severe cases: fluid resuscitation, broad-spectrum antibiotics, and possible surgical intervention if perforation occurs
Common Pitfalls to Avoid
- Delaying rehydration while awaiting diagnostic results
- Using antimotility agents in children or patients with bloody diarrhea
- Unnecessary antibiotic use for viral or self-limiting diarrhea
- Withholding food during diarrheal episodes
- Failing to monitor renal function in elderly patients receiving oral vancomycin for C. difficile
- Not considering C. difficile in patients with recent antibiotic exposure
- Overlooking epidemiological risk factors that may guide targeted therapy
Remember that most episodes of infectious diarrhea are self-limited, and the primary focus should be on preventing dehydration while addressing any specific pathogens when indicated by clinical presentation or diagnostic testing.