Empiric Antibiotic Treatment for Diarrhea

Introduction to Empiric Antibiotic Treatment

• The Infectious Diseases Society of America recommends that for most adults with acute watery diarrhea, empiric antibiotics are not recommended; however, azithromycin 500 mg daily for 3 days (or 1000 mg single dose for severe cases) is the first-line empiric antibiotic when treatment is indicated based on specific high-risk features 1, 2

When to Withhold Empiric Antibiotics

• The Infectious Diseases Society of America suggests that in immunocompetent adults with acute watery diarrhea without recent international travel, empiric antimicrobial therapy is not recommended 3
• The average benefit of empiric antibiotic use is only 1 day shorter illness duration, which does not outweigh risks in most cases 3, 4

When Empiric Antibiotics ARE Indicated

• Empiric treatment should be initiated in patients with fever ≥38.5°C documented in a medical setting PLUS bloody diarrhea 1
• Empiric treatment should be initiated in patients with signs of sepsis or severe systemic illness 1, 2
• Empiric treatment should be initiated in patients with bacillary dysentery presentation (frequent scant bloody stools, fever, abdominal cramps, tenesmus) presumptively due to Shigella 1, 5
• Empiric treatment should be initiated in patients with recent international travel with fever ≥38.5°C 1

First-Line Empiric Antibiotic Choice

• The American College of Gastroenterology recommends azithromycin as the preferred first-line empiric antibiotic for adults requiring treatment 1, 2, 6
• Azithromycin is effective against most bacterial pathogens including Shigella, Campylobacter, and ETEC 6
• Azithromycin is preferred for Southeast Asia travel due to >85% fluoroquinolone resistance in that region 6
• Azithromycin is safe in pregnancy and children 6

Alternative Empiric Antibiotics

• The Infectious Diseases Society of America suggests that ciprofloxacin 500 mg twice daily or levofloxacin 750 mg once daily for 1-3 days may be used depending on local susceptibility patterns and travel history 1, 5, 7
• Fluoroquinolones should NOT be used for Southeast Asia travel 6
• Fluoroquinolones have FDA warnings regarding musculoskeletal adverse effects 8

Pediatric Empiric Therapy

• The American Academy of Pediatrics recommends that for children requiring empiric treatment, infants <3 months should receive third-generation cephalosporin 1
• The American Academy of Pediatrics recommends that for children requiring empiric treatment, older children should receive azithromycin based on local susceptibility patterns and travel history 1, 6
• Fluoroquinolones should be avoided in children <6 years 6
• Doxycycline should be avoided in children <8 years due to risk of permanent tooth discoloration 6

Critical Contraindications

• The Infectious Diseases Society of America recommends that antibiotics should be avoided for STEC O157 and other STEC producing Shiga toxin 2, as they significantly increase the risk of hemolytic uremic syndrome 1, 4, 2
• Shiga toxin testing should be performed before initiating antibiotics in bloody diarrhea 2

Adjunctive Therapy

• The Infectious Diseases Society of America suggests that loperamide may be combined with antibiotics to reduce symptom duration and severity 8, 6
• Loperamide reduces illness duration from 59 hours to approximately 1 hour when combined with azithromycin 6
• Loperamide should be discontinued immediately if fever, bloody stools, or severe abdominal pain develops 6