What antibiotics, including doses, can be used for treatment of bacterial gastroenteritis?

Antibiotic Treatment for Bacterial Gastroenteritis

Azithromycin is the preferred first-line antibiotic for treatment of bacterial gastroenteritis, with a recommended dose of 500 mg once daily for 3 days or 1000 mg as a single dose for severe cases. 1, 2

First-Line Antibiotic Options

Azithromycin

• Recommended dose: 500 mg orally once daily for 3 days or 1000 mg as a single dose 1
• Preferred for severe gastroenteritis, dysentery, and in regions with high fluoroquinolone resistance 1, 2
• First-line choice for suspected Campylobacter infections due to increasing fluoroquinolone resistance 1, 3

Fluoroquinolones

• Ciprofloxacin: 500 mg orally twice daily or 750 mg once daily for 3 days (or single dose for mild cases) 1, 2
• Levofloxacin: 500 mg orally once daily for 3 days (or single dose for mild cases) 1
• Ofloxacin: 400 mg orally once daily for 3 days (or single dose for mild cases) 1
• Not recommended for suspected Campylobacter infections or in regions with high fluoroquinolone resistance 1

Rifaximin

• Dose: 200 mg orally three times daily for 3 days 1, 2
• Only for non-invasive, watery diarrhea (not for dysentery or febrile illness) 1, 2

Pathogen-Specific Treatment

Salmonella (non-typhoidal)

• First-line: Ciprofloxacin 400 mg IV twice daily or 500 mg orally twice daily 1
• Alternatives: Levofloxacin 500 mg once daily, Amoxicillin 500 mg three times daily, or TMP-SMX 160/800 mg twice daily 1
• For bacteremia: Ceftriaxone 2 g IV once daily plus Ciprofloxacin 500 mg IV twice daily 1

Shigella

• First-line: Fluoroquinolones (e.g., Ciprofloxacin 400 mg IV twice daily or 500 mg orally twice daily) 1
• Alternative: Azithromycin 500 mg once daily IV/PO 1, 3

Campylobacter

• First-line: Azithromycin 500 mg once daily IV/PO 1, 2
• Alternative (if susceptible): Fluoroquinolones (e.g., Ciprofloxacin 400 mg IV twice daily or 500 mg orally twice daily) 1

Yersinia

• First-line: Fluoroquinolones (e.g., Ciprofloxacin 400 mg IV twice daily or 500 mg orally twice daily) 1
• Alternatives: TMP-SMX 160/800 mg twice daily or Doxycycline 100 mg twice daily 1
• For bacteremia: Ceftriaxone 2 g IV once daily plus Gentamicin 5 mg/kg IV once daily 1

Clostridium difficile Treatment

• Mild to moderate infection: Metronidazole 500 mg orally three times daily for 10 days 1
• Severe infection: Vancomycin 125 mg orally four times daily for 10 days 1
• If oral therapy impossible: Metronidazole 500 mg IV three times daily for 10 days 1

Treatment Considerations

When to Use Antibiotics

• Antibiotics are not routinely recommended for most cases of bacterial gastroenteritis 4, 5
• Consider antibiotics for:
  • Severe illness (high fever, bloody diarrhea, severe abdominal pain) 1, 4
  • Immunocompromised patients 1, 4
  • Travelers' diarrhea affecting daily activities 1, 2
  • Confirmed Shigella infection 4, 5

Adjunctive Therapy

• Loperamide may be combined with antibiotics in adults with non-dysenteric, non-febrile diarrhea 1
  • Initial dose: 4 mg, then 2 mg after each loose stool (maximum 16 mg/day) 1
  • Avoid in children under 18 years and in cases of bloody or febrile diarrhea 4

Duration of Therapy

• Single-dose regimens are effective for mild to moderate cases 1, 2
• 3-day courses are standard for most bacterial pathogens 1, 2
• Longer courses (7-10 days) may be needed for severe infections or immunocompromised patients 1

Special Populations

Immunocompromised Patients

• Lower threshold for initiating antibiotic therapy 1, 4
• Consider broader spectrum coverage initially 1
• May require longer treatment duration 1

Pediatric Considerations

• Azithromycin is preferred for children with suspected bacterial gastroenteritis requiring antibiotics 4, 6
• Avoid fluoroquinolones in children if possible 4
• Avoid antimotility agents in children under 18 years 4

Pitfalls and Caveats

• Avoid antibiotics for suspected STEC O157 infections as they may increase risk of hemolytic uremic syndrome 4
• Antibiotic resistance is increasing, particularly fluoroquinolone resistance in Campylobacter 1, 3
• Most cases of bacterial gastroenteritis are self-limiting and do not require antibiotics 4, 5
• Rehydration therapy remains the cornerstone of treatment for all cases 4
• Consider local resistance patterns when selecting empiric therapy 1, 3