What is the best antibiotic for bacterial acute gastroenteritis (infection of the stomach and intestines) if needed?

Best Antibiotic for Bacterial Acute Gastroenteritis

Azithromycin is the first-line antibiotic treatment for bacterial acute gastroenteritis when antibiotics are needed, particularly for dysentery or severe cases of infection. 1

When Antibiotics Are Indicated

• Most cases of acute gastroenteritis are viral in origin and do not require antibiotic treatment 1
• Antibiotics should only be prescribed when:
  • Severe non-dysenteric watery diarrhea leading to incapacitation 1
  • Dysentery (bloody diarrhea) 1
  • Severe cases with fever suggesting invasive disease 1
  • Immunocompromised patients or those with significant underlying conditions 2

First-Line Antibiotic Choice

• Azithromycin (500mg once daily for 3 days or 1g single dose in adults) is the preferred first-line agent because:
  • Superior efficacy against Campylobacter, including fluoroquinolone-resistant strains 1
  • Effective against Shigella species 1, 3
  • Lower risk of promoting antimicrobial resistance compared to fluoroquinolones 1
  • Well-tolerated with minimal side effects (primarily gastrointestinal) 4

Alternative Antibiotic Options

• Fluoroquinolones (e.g., ciprofloxacin):

  • No longer recommended as first-line due to increasing resistance, particularly in Campylobacter 1
  • May be used in areas with known low resistance rates 1
  • Should be avoided if patient received quinolone therapy within the past 3 months 1

• Sulfamethoxazole-trimethoprim:

  • Alternative option for mild cases 1
  • Increasing resistance limits its use in many regions 1

• Rifaximin:

  • Option for non-invasive, watery diarrhea (particularly traveler's diarrhea) 1
  • Poorly absorbed, limiting systemic effects 1

Pathogen-Specific Considerations

• Campylobacter: Azithromycin is the drug of choice, especially for severe cases 3
• Shigella: Azithromycin is preferred; alternatives include ciprofloxacin or ceftriaxone 3
• Salmonella: Antibiotics only indicated for severe cases, with ceftriaxone or ciprofloxacin recommended 3
• Vibrio cholerae: Azithromycin or doxycycline 1
• Yersinia: Doxycycline or fluoroquinolones 5

Duration of Treatment

• Short-course therapy is generally sufficient:
  • Azithromycin: 3 days or single 1g dose 1
  • Fluoroquinolones: 3 days or single dose for mild cases 1
  • Treatment should reduce symptom duration from 50-93 hours to 16-30 hours 1

Special Populations

• Children: Azithromycin is the preferred agent; avoid fluoroquinolones when possible 3
• Pregnant women: Avoid doxycycline; azithromycin is generally considered safe 5
• Immunocompromised: May require longer treatment courses and broader coverage 1

Important Caveats

• Empirical antibiotic treatment without bacteriological documentation should generally be avoided in mild cases 3
• Overuse of antibiotics contributes to antimicrobial resistance and can disrupt gut microbiota 6
• Consider local resistance patterns when selecting antibiotics 7
• Antibiotics should always be accompanied by appropriate rehydration therapy 1
• In cases of intra-abdominal infections or complications, broader coverage may be needed 1