What is the appropriate antibiotic therapy for patients with diarrhea?

Antibiotic Therapy for Patients with Diarrhea

For most patients with acute watery diarrhea without recent international travel, empiric antimicrobial therapy is not recommended as the condition is typically self-limiting. 1

When to Consider Antibiotics

Empiric antibiotic therapy should be limited to specific clinical scenarios:

Bloody Diarrhea

• Antibiotics are generally not recommended for immunocompetent children and adults with bloody diarrhea while awaiting diagnostic results 1
• Exceptions include:
  • Infants <3 months of age with suspected bacterial etiology 1
  • Immunocompetent patients with documented fever, abdominal pain, bloody diarrhea, and bacillary dysentery (frequent scant bloody stools, fever, abdominal cramps, tenesmus) presumptively due to Shigella 1
  • Recent international travelers with temperatures ≥38.5°C and/or signs of sepsis 1
  • Immunocompromised patients with severe illness and bloody diarrhea 1

Watery Diarrhea

• Empiric antibiotics are generally not indicated for acute watery diarrhea 1
• Consider antibiotics only for:
  • Immunocompromised patients 1
  • Ill-appearing young infants 1
  • Severe cases in high-risk patients (elderly, diabetics, cirrhotics) 2, 3
• Avoid empiric treatment in persistent watery diarrhea lasting ≥14 days 1

Antibiotic Selection

When antibiotics are indicated, selection should be guided by:

For Adults

• First-line options:
  • Fluoroquinolones (e.g., ciprofloxacin 500-750mg) OR
  • Azithromycin (500mg for acute watery diarrhea; 1000mg for febrile diarrhea/dysentery)
  • Selection depends on local susceptibility patterns and travel history 1, 4

For Children

• First-line options:
  • Third-generation cephalosporin for infants <3 months or those with neurologic involvement 1
  • Azithromycin based on local susceptibility patterns and travel history 1, 5

For Specific Pathogens

• Clostridium difficile: Oral vancomycin (125mg four times daily for 10 days) 6
• Shigella: Prompt treatment with azithromycin 5, 4
• Salmonella: No treatment for moderate cases; treat severe cases or high-risk patients with ciprofloxacin or ceftriaxone 5, 3
• Campylobacter: Treatment recommended for early diagnosis 5, 2
• STEC O157 and other Shiga toxin 2-producing strains: Avoid antibiotics 1

Special Considerations

• Enteric fever: Treat empirically with broad-spectrum antibiotics after collecting blood, stool, and urine cultures; narrow therapy once susceptibility results are available 1
• Traveler's diarrhea: Consider azithromycin or ciprofloxacin, accounting for local resistance patterns 2, 4
• Antibiotic-associated diarrhea: Discontinue the offending antibiotic if possible; treat C. difficile if confirmed 6, 7

Important Caveats

• Asymptomatic contacts of patients with diarrhea should not receive empiric antibiotics 1
• Modify or discontinue antibiotics when a specific pathogen is identified 1
• Consider non-infectious causes (IBD, IBS, lactose intolerance) in patients with symptoms lasting ≥14 days 1
• The primary treatment for most infectious diarrhea is adequate rehydration with oral rehydration solution (ORS) 1
• Antimotility agents like loperamide can be considered in adults once adequately hydrated but should not be given to children <18 years 1, 4
• Prudent use of antibiotics is essential to limit the increasing problem of antibiotic resistance among enteric pathogens 2, 3

Monitoring and Follow-up

• Reassess fluid and electrolyte balance, nutritional status, and antibiotic efficacy in patients with persistent symptoms 1
• Clinical and laboratory reevaluation may be needed for non-responders 1
• Follow-up stool testing is generally not recommended after symptom resolution except in certain situations required by local health authorities 1