What is the treatment for infectious diarrhea?

Treatment of Infectious Diarrhea

The cornerstone of infectious diarrhea treatment is oral rehydration solution (ORS) for all patients with mild to moderate dehydration, while empiric antibiotics should be reserved for specific high-risk scenarios including bloody diarrhea with fever, severe illness in immunocompromised patients, or travelers with febrile dysentery. 1

Rehydration: The Foundation of Treatment

Reduced osmolarity ORS is first-line therapy for mild to moderate dehydration in all age groups, regardless of the underlying pathogen 1. This takes priority over antimicrobial therapy in most cases.

Rehydration Algorithm by Severity:

Mild to Moderate Dehydration:

• Administer ORS orally until clinical dehydration is corrected 1
• If oral intake is not tolerated, consider nasogastric ORS administration in patients with normal mental status 1
• Continue ORS to replace ongoing stool losses until diarrhea resolves 1

Severe Dehydration (shock, altered mental status, or ORS failure):

• Start isotonic IV fluids (lactated Ringer's or normal saline) immediately 1
• Continue IV rehydration until pulse, perfusion, and mental status normalize 1
• Transition to ORS once the patient is stable and can tolerate oral intake 1

Antimicrobial Therapy: When and What to Use

Acute Watery Diarrhea (Non-Bloody)

In most patients with acute watery diarrhea without recent international travel, empiric antimicrobial therapy is NOT recommended 1. This is a strong recommendation that prevents unnecessary antibiotic exposure and resistance development.

Exceptions warranting empiric antibiotics:

• Immunocompromised patients with severe illness 1
• Ill-appearing young infants 1
• Recent international travelers with fever ≥38.5°C or signs of sepsis 1, 2

Bloody Diarrhea (Dysentery)

For adults with bloody diarrhea, empiric treatment should be either:

• Fluoroquinolone (ciprofloxacin) based on local susceptibility patterns and travel history 1
• Azithromycin as an alternative, particularly in areas with fluoroquinolone resistance 1

For children with bloody diarrhea:

• Third-generation cephalosporin for infants <3 months or those with neurologic involvement 1
• Azithromycin for older children, depending on local susceptibility patterns 1

Critical Exception: STEC Infections

Antimicrobial therapy should be AVOIDED in infections with STEC O157 and other Shiga toxin 2-producing E. coli 1. This is a strong recommendation because antibiotics may increase the risk of hemolytic uremic syndrome 2. When STEC is suspected or confirmed, withhold antibiotics regardless of symptom severity.

Enteric Fever (Typhoid)

Patients with clinical features of sepsis and suspected enteric fever require:

• Immediate broad-spectrum antimicrobial therapy after obtaining blood, stool, and urine cultures 1
• Narrow therapy once susceptibility results are available 1
• Ciprofloxacin is FDA-approved for typhoid fever caused by Salmonella typhi 3

Treatment Modification

Antimicrobial treatment should be modified or discontinued when a specific pathogen is identified 1. This prevents unnecessary broad-spectrum coverage and reduces resistance pressure.

Nutritional Management

Continue age-appropriate diet during or immediately after rehydration 1. The outdated practice of withholding food during diarrheal episodes should be avoided 2.

• Breastfeeding infants: Continue human milk feeding throughout the episode 1, 2
• All patients: Resume normal diet as soon as rehydration is achieved 1, 2

Adjunctive Therapies

Antimotility Agents

Loperamide may be given to immunocompetent adults with acute watery diarrhea 1, 2, but with critical restrictions:

Absolute contraindications for loperamide:

• Children <18 years of age 1, 2
• Bloody or inflammatory diarrhea (risk of toxic megacolon) 2, 4
• Patients with fever suggesting invasive infection 4
• Higher than recommended doses (risk of cardiac arrhythmias, including Torsades de Pointes) 4

Antiemetics

Antinausea/antiemetic agents can be considered once adequate hydration is achieved, but are not a substitute for fluid therapy 1, 2. They may facilitate oral rehydration when vomiting is present 2.

Common Pitfalls to Avoid

Critical errors that worsen outcomes:

1. Using antibiotics for routine acute watery diarrhea - This promotes resistance without clinical benefit 1, 2

2. Administering antimotility agents to children or patients with bloody diarrhea - Risk of toxic megacolon and prolonged pathogen shedding 1, 2, 4

3. Giving antibiotics for suspected or confirmed STEC infections - Increases hemolytic uremic syndrome risk 1, 2

4. Neglecting rehydration while focusing on antimicrobials - Dehydration causes more morbidity than the infection itself in most cases 1, 2

5. Withholding food during illness - Delays recovery and worsens nutritional status 1, 2

6. Using loperamide in combination with drugs that prolong QT interval - Risk of fatal cardiac arrhythmias 4

Special Populations

Immunocompromised patients:

• Lower threshold for empiric antibiotics with severe illness and bloody diarrhea 1
• Consider empiric treatment even with watery diarrhea if ill-appearing 1

Pediatric patients <2 years:

• Loperamide is contraindicated due to risks of respiratory depression and cardiac adverse reactions 4
• Maintain high suspicion for dehydration, which develops more rapidly than in adults 1

Asymptomatic contacts:

• Do not offer empiric or preventive therapy 1
• Advise appropriate infection prevention and hand hygiene measures 1, 2