What is the first line management for infectious diarrhea?

First-Line Management for Infectious Diarrhea

Reduced osmolarity oral rehydration solution (ORS) is the first-line therapy for mild to moderate dehydration in all patients with infectious diarrhea, regardless of age. 1

Rehydration: The Cornerstone of Management

The primary goal in managing infectious diarrhea is preventing and treating dehydration, which represents the most significant risk for morbidity and mortality. 1

Oral Rehydration Therapy

• ORS is superior to intravenous fluids for patients who can tolerate oral intake—it is safer, less painful, less costly, and equally effective. 1
• The WHO-recommended reduced osmolarity formulation contains approximately Na 90 mM, K 20 mM, Cl 80 mM, HCO₃ 30 mM, and glucose 111 mM. 1
• Commercial preparations (Pedialyte, Ceralyte) are readily available and appropriate. 1
• For patients with moderate dehydration who cannot tolerate oral intake, nasogastric administration of ORS may be considered. 1

Intravenous Rehydration

• Reserve IV fluids for severe dehydration, shock, altered mental status, or failure of ORS therapy. 1
• Use isotonic fluids such as lactated Ringer's or normal saline. 1
• Continue IV rehydration until pulse, perfusion, and mental status normalize, then transition to ORS for remaining deficit replacement. 1
• Patients with ketonemia may require initial IV hydration to enable tolerance of oral rehydration. 1

Maintenance and Ongoing Losses

• Once rehydrated, administer maintenance fluids and replace ongoing stool losses with ORS until diarrhea and vomiting resolve. 1

Nutritional Management

Resume age-appropriate diet immediately during or after rehydration—do not withhold food. 1

• Continue breastfeeding throughout the diarrheal episode in infants and children. 1
• Early realimentation prevents malnutrition and may reduce stool output. 1
• In children 6 months to 5 years in zinc-deficient regions or with malnutrition, oral zinc supplementation reduces diarrhea duration. 1

Antimicrobial Therapy: When to Avoid and When to Consider

Empiric antimicrobial therapy is NOT recommended for most patients with acute watery diarrhea without recent international travel. 1

Exceptions for Empiric Antimicrobials

Consider antimicrobial therapy only in these specific circumstances: 1

• Immunocompromised patients with severe illness
• Ill-appearing young infants (especially <3 months)
• Bloody diarrhea with presumptive shigellosis
• Recent international travelers with fever ≥38.5°C or signs of sepsis
• Clinical features of sepsis with suspected enteric fever

Critical Contraindication

Avoid antimicrobials in STEC O157 and other Shiga toxin 2-producing E. coli infections—they may increase risk of hemolytic uremic syndrome. 1

Modification Based on Culture Results

• Modify or discontinue antimicrobial treatment when a specific organism is identified. 1
• Tailor therapy based on antimicrobial susceptibility testing. 1

Adjunctive Therapies: Use With Caution

Antimotility Agents

• Never give antimotility drugs (loperamide) to children <18 years with acute diarrhea. 1
• Loperamide may be given to immunocompetent adults with acute watery diarrhea ONLY after adequate hydration. 1, 2
• Avoid loperamide in any patient with bloody diarrhea, fever, or suspected inflammatory diarrhea due to risk of toxic megacolon. 1
• Discontinue after 12 hours diarrhea-free. 3
• Use prescribed dosages only—higher doses can cause cardiac arrhythmias and QT prolongation. 2

Antiemetics

• Ondansetron may be given to children >4 years and adolescents to facilitate oral rehydration when vomiting is present. 1
• Consider antiemetics in adults after ensuring adequate hydration. 3

Probiotics

• May be offered to reduce symptom severity and duration in immunocompetent patients, though evidence is moderate. 1

Clinical Algorithm

1. Assess hydration status (thirst, orthostasis, decreased urination, dry mucous membranes, altered mental status). 1
2. Mild-moderate dehydration: Administer ORS until clinical dehydration corrected. 1
3. Severe dehydration: Start IV isotonic fluids until stabilized, then transition to ORS. 1
4. Continue appropriate diet throughout illness—do not withhold food. 1
5. Avoid empiric antimicrobials unless specific high-risk features present. 1
6. Replace ongoing losses with ORS until symptoms resolve. 1

Common Pitfalls to Avoid

• Do not use antimotility agents in children or patients with bloody/febrile diarrhea—risk of toxic megacolon and prolonged illness. 1
• Do not routinely prescribe antimicrobials for acute watery diarrhea—most cases are self-limited and antibiotics provide no benefit. 1
• Do not neglect rehydration while focusing on antimicrobial therapy—dehydration is the primary threat. 1
• Do not withhold food during diarrheal episodes—early feeding prevents malnutrition and aids recovery. 1
• Do not use antimicrobials in suspected STEC infections—may precipitate hemolytic uremic syndrome. 1
• Do not use loperamide at higher than recommended doses—cardiac toxicity risk. 2