When should antibiotics be used to treat gastroenteritis?

When to Use Antibiotics for Gastroenteritis

Antibiotics should not be routinely used for most cases of acute gastroenteritis, as the majority are self-limiting viral infections or bacterial infections that resolve without antimicrobial therapy. 1

Indications for Antibiotic Treatment

Specific Clinical Scenarios Requiring Antibiotics

1. Severe illness with specific features:

   • Bloody diarrhea with fever and abdominal pain (bacillary dysentery) 1
   • Fever ≥38.5°C with signs of sepsis, particularly in recent international travelers 1
   • Clinical features of sepsis with suspected enteric fever 1
   • Severe dehydration with systemic toxicity 1

2. Patient-specific factors:

   • Infants <3 months of age with suspected bacterial etiology 1
   • Immunocompromised patients with severe illness and bloody diarrhea 1
   • HIV-infected patients with Salmonella gastroenteritis (to prevent extraintestinal spread) 1
   • Elderly patients with severe symptoms 2

3. Specific pathogens:

   • Confirmed shigellosis or strong clinical suspicion 3
   • Severe Salmonella gastroenteritis (not mild or moderate cases) 1, 3
   • Early diagnosed Campylobacter jejuni infection 3
   • Traveler's diarrhea that is severe or not responding to supportive care 1

Contraindications for Antibiotic Use

• STEC (Shiga toxin-producing E. coli) O157 and other STEC that produce Shiga toxin 2 - antibiotics should be avoided as they may increase the risk of hemolytic uremic syndrome 1
• Mild to moderate uncomplicated gastroenteritis in immunocompetent hosts 1, 4
• Asymptomatic contacts of people with bloody diarrhea 1

Antibiotic Selection by Clinical Scenario

Empiric Treatment for Adults

1. For severe non-dysenteric diarrhea:

   • Fluoroquinolone (e.g., ciprofloxacin 500mg twice daily) OR
   • Azithromycin (1g single dose or 500mg daily for 3 days) 1

2. For dysentery or febrile diarrhea:

   • Azithromycin is preferred (strong recommendation) 1
   • Consider local resistance patterns when selecting therapy 1

3. For traveler's diarrhea:

   • Fluoroquinolone (e.g., ciprofloxacin 750mg twice daily for up to 3 days) 1
   • In Southeast Asia and India: Azithromycin preferred due to fluoroquinolone-resistant Campylobacter 1

Empiric Treatment for Children

1. Infants <3 months with suspected bacterial etiology:

   • Third-generation cephalosporin (e.g., ceftriaxone) 1

2. Children with neurologic involvement:

   • Third-generation cephalosporin 1

3. Other pediatric cases requiring antibiotics:

   • Azithromycin (based on local susceptibility patterns) 1, 3
   • Avoid fluoroquinolones in children <18 years unless no alternatives exist 1

Treatment for Specific Pathogens

1. Shigellosis:

   • Azithromycin (preferred) 3

2. Salmonella (severe cases or high-risk patients):

   • Ciprofloxacin or ceftriaxone 3
   • For HIV-infected patients with Salmonella septicemia: long-term therapy to prevent recurrence 1

3. Campylobacter:

   • Azithromycin (especially if diagnosed early) 3

Duration of Therapy

• Single-dose regimens may be effective for moderate to severe traveler's diarrhea 1
• 3-day courses are typical for most uncomplicated infections requiring treatment 1
• 14-day course for Salmonella gastroenteritis in HIV-infected patients 1

Important Considerations

• Modify or discontinue antibiotics when a specific pathogen is identified and susceptibilities are known 1
• Rehydration therapy is the cornerstone of treatment for all cases of gastroenteritis, regardless of antibiotic use 1
• Monitor for resistance as local patterns may affect empiric therapy choices 4
• Avoid antiperistaltic agents (e.g., loperamide) in patients with high fever or bloody stools 1

Special Populations

Immunocompromised Patients

• Lower threshold for initiating antibiotics 1, 4
• Consider longer duration of therapy (up to 7 days) 5
• Monitor response closely with inflammatory markers 5

Pregnant Women

• Avoid fluoroquinolones 1
• For Salmonella: ampicillin, cefotaxime, ceftriaxone, or TMP-SMZ 1

HIV-Infected Patients

• More aggressive approach to antibiotic treatment, particularly for Salmonella 1
• Consider long-term suppressive therapy for recurrent Salmonella bacteremia 1

By following these guidelines, clinicians can make appropriate decisions about when to use antibiotics for gastroenteritis, balancing the need to treat serious bacterial infections while avoiding unnecessary antimicrobial use that could contribute to resistance.