What antibiotics are recommended for treating bacterial gastroenteritis?

Antibiotics for Bacterial Gastroenteritis

Empiric antibiotic therapy is not recommended for most cases of bacterial gastroenteritis, as most infections are self-limiting. 1, 2

When to Consider Antibiotics

Antibiotics should only be used in specific circumstances:

• Infants <3 months of age with suspected bacterial etiology 1
• Immunocompromised patients with severe illness and bloody diarrhea 1
• Patients with 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
• Patients with clinical features of sepsis who are suspected of having enteric fever 1

Recommended Antibiotics by Patient Population

Adults

• First-line options:
  • Fluoroquinolones (e.g., ciprofloxacin 400 mg IV twice daily or 500 mg PO twice daily) 1
  • Azithromycin 500 mg daily (IV/PO) - especially for areas with high fluoroquinolone resistance 1

Children

• Infants <3 months: Third-generation cephalosporin (e.g., ceftriaxone) 1
• Older children: Azithromycin, depending on local susceptibility patterns and travel history 1

Pathogen-Specific Recommendations

Salmonella

• Uncomplicated diarrhea: Ciprofloxacin 400 mg twice daily IV or 500 mg twice daily PO 1
• Alternatives: Levofloxacin 500 mg daily PO, amoxicillin 500 mg three times daily PO, or TMP-SMX 160/180 mg twice daily PO/IV 1
• Bacteremia: Ceftriaxone 2 g daily IV plus ciprofloxacin 500 mg twice daily IV 1

Shigella

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

Campylobacter

• First-line: Azithromycin 500 mg daily IV/PO 1
• Alternative: Fluoroquinolones (note: high resistance rates of approximately 19%) 1

Yersinia

• Diarrhea: Fluoroquinolones (e.g., ciprofloxacin 400 mg twice daily IV or 500 mg twice daily PO) 1
• Alternatives: TMP-SMX 160/180 mg twice daily PO/IV or doxycycline 100 mg twice daily IV/PO 1
• Bacteremia: Ceftriaxone 2 g daily IV plus gentamicin 5 mg/kg daily IV 1

Important Considerations and Cautions

• Avoid antibiotics for STEC O157 and other Shiga toxin 2-producing organisms as they may increase the risk of hemolytic uremic syndrome 1
• Do not treat asymptomatic contacts of people with bacterial gastroenteritis 1
• Discontinue antibiotics when a satisfactory clinical response occurs, even if initially untreated pathogens are later reported 1
• Tailor therapy when culture and susceptibility results become available 1
• Avoid ampicillin-sulbactam due to high rates of resistance among community-acquired E. coli 1
• Monitor for antibiotic resistance, which is widespread among enteric pathogens and can quickly spread during epidemics 3

Duration of Treatment

• Most uncomplicated infections require 3-5 days of treatment 1, 4
• Severe infections or bacteremia may require longer courses (10-14 days) 1

Follow-up

• Clinical and laboratory reevaluation may be indicated in people who do not respond to initial therapy 1
• Consider non-infectious conditions (e.g., IBD, IBS) in patients with symptoms lasting 14 days or more 1
• Reassess fluid and electrolyte balance and nutritional status in patients with persistent symptoms 1