What is the treatment for diarrhea when a possible infection is suspected?

Treatment of Suspected Infectious Diarrhea

Rehydration is the cornerstone of treatment for all patients with suspected infectious diarrhea, while empiric antibiotics should be reserved for specific high-risk scenarios only. 1, 2

Immediate Assessment and Rehydration Strategy

Assess hydration status first: Mild dehydration (3-5% fluid deficit), moderate (6-9%), or severe (≥10%) based on clinical signs including mental status, pulse, perfusion, skin turgor, and presence of sunken eyes 2.

Rehydration Protocol

For mild-to-moderate dehydration:

• Use reduced osmolarity oral rehydration solution (ORS) as first-line therapy (50-90 mEq/L sodium) 1, 2
• Administer 50 mL/kg over 2-4 hours for mild dehydration 2
• Administer 100 mL/kg over 2-4 hours for moderate dehydration 2
• Start with small volumes (one teaspoon) using syringe or dropper, gradually increasing as tolerated 2
• Nasogastric ORS may be considered if oral intake is not tolerated 1

For severe dehydration:

• Administer isotonic intravenous fluids (lactated Ringer's or normal saline) immediately when there is severe dehydration, shock, altered mental status, or ileus 1
• Continue IV rehydration until pulse, perfusion, and mental status normalize 1
• Switch to ORS once patient is stable and can tolerate oral intake 1

Empiric Antibiotic Therapy: When to Treat

Most patients with acute watery diarrhea should NOT receive empiric antibiotics 2, 3. However, empiric treatment is indicated in these specific scenarios:

Clear Indications for Empiric Antibiotics

Treat empirically if:

• Infants <3 months of age with suspected bacterial etiology 1, 3
• Ill patients with fever (documented in medical setting), abdominal pain, bloody diarrhea, and bacillary dysentery (frequent scant bloody stools, fever, cramps, tenesmus) presumptively due to Shigella 1, 3
• Recent international travelers with temperature ≥38.5°C and/or signs of sepsis 1, 3
• Immunocompromised patients with severe illness and bloody diarrhea 1, 3
• Suspected enteric fever with clinical features of sepsis (after obtaining blood, stool, and urine cultures) 1, 3

Antibiotic Selection

For adults:

• Fluoroquinolone (ciprofloxacin 750 mg single dose or 500 mg twice daily for 3 days) OR azithromycin (1 gram single dose or 500 mg daily for 3 days) based on local susceptibility patterns and travel history 1, 3, 4
• Prefer azithromycin for Southeast Asia/India travel due to high fluoroquinolone-resistant Campylobacter rates 3

For children:

• Third-generation cephalosporin for infants <3 months or those with neurologic involvement 1, 3
• Azithromycin for other children based on local susceptibility patterns and travel history 1, 3

Critical Contraindications

AVOID antibiotics in:

• STEC O157 and other Shiga toxin 2-producing E. coli infections due to increased risk of hemolytic uremic syndrome 1, 3
• Asymptomatic contacts of patients with diarrhea 1, 3
• Most immunocompetent patients with acute watery diarrhea without the specific indications listed above 2, 3

Adjunctive Medications

Antimotility Agents (Loperamide)

Loperamide is CONTRAINDICATED in:

• All children <18 years of age with acute diarrhea 1, 2, 5
• ALL ages with inflammatory diarrhea, fever, or bloody stools due to toxic megacolon risk 1, 2, 5

May consider loperamide only in:

• Immunocompetent adults with acute watery diarrhea (non-bloody, afebrile) after adequate hydration 1

Antiemetics

Ondansetron may be used:

• In children >4 years and adolescents with vomiting to facilitate oral rehydration 1, 2
• Only after adequate hydration begins; not a substitute for fluid therapy 2

Probiotics and Zinc

Probiotics:

• May be offered to reduce symptom severity and duration in immunocompetent patients with infectious diarrhea 1

Zinc supplementation:

• Reduces diarrhea duration in children 6 months to 5 years in countries with high zinc deficiency prevalence or signs of malnutrition 1

Nutritional Management

Resume age-appropriate diet immediately:

• Continue breastfeeding throughout illness 1, 2
• Resume normal diet during or immediately after rehydration 1, 2
• Use full-strength lactose-free or lactose-reduced formulas for bottle-fed infants 2
• Avoid fatty, heavy, spicy foods and caffeine initially 2

Infection Control

Rigorous hand hygiene is essential:

• Perform after toilet use, diaper changes, before food preparation/eating, after handling garbage or animals 1
• Use gloves, gowns, and soap-and-water or alcohol-based sanitizers when caring for patients with diarrhea 1, 2

Common Pitfalls to Avoid

Critical errors include:

• Overusing empiric antibiotics in uncomplicated diarrhea, which promotes antimicrobial resistance 3
• Using antibiotics in STEC infections, which increases hemolytic uremic syndrome risk 1, 3
• Giving loperamide to children or patients with bloody/febrile diarrhea, risking toxic megacolon 1, 2, 5
• Neglecting rehydration while focusing on antimicrobial treatment 3
• Failing to consider geographic resistance patterns when selecting antibiotics 3

Modify or discontinue antimicrobial treatment when a specific organism is identified and tailor therapy to susceptibility results 1, 3.