When should antibiotics be given to a patient with acute diarrhea and nausea, considering factors such as severity of disease, immunocompromised state, and recent travel history?

Antibiotic Therapy for Acute Diarrhea and Nausea

Most patients with acute diarrhea should NOT receive antibiotics, as the illness is typically self-limited and antibiotics add unnecessary risk of adverse effects and antimicrobial resistance. 1

When to Give Antibiotics

Immunocompetent Adults and Children

Do NOT give empiric antibiotics for acute watery diarrhea without recent international travel. 1 The exception is for immunocompromised patients or ill-appearing young infants. 1

Give empiric antibiotics for bloody diarrhea ONLY in these specific scenarios: 1

• Infants <3 months of age with suspected bacterial etiology 1
• Ill patients with documented fever in a medical setting, abdominal pain, bloody diarrhea, and bacillary dysentery (frequent scant bloody stools, fever, abdominal cramps, tenesmus) presumptively due to Shigella 1
• Recent international travelers with body temperature ≥38.5°C and/or signs of sepsis 1

Immunocompromised Patients

Empiric antibacterial treatment should be strongly considered in immunocompromised patients with severe illness and bloody diarrhea. 1 This population is at higher risk for complications and disseminated disease. 2

For immunocompromised patients with otherwise uncomplicated Campylobacter gastroenteritis, treatment is reasonable despite lack of strong evidence, as fatal infections are more common in severely immunocompromised hosts. 1

Traveler's Diarrhea Context

For moderate to severe traveler's diarrhea (distressing or incapacitating symptoms), antibiotics are indicated. 3

Azithromycin is the preferred first-line agent: 3

• Single 1-gram dose OR
• 500 mg daily for 3 days

Regional considerations are critical: 3

• In Southeast Asia, azithromycin is clearly superior due to fluoroquinolone resistance exceeding 85-90% for Campylobacter 3
• Fluoroquinolones may be considered for severe non-dysenteric cases ONLY in regions with low resistance (<15%) 3

Antibiotic Selection

First-Line Empiric Therapy

For adults with bloody diarrhea meeting treatment criteria: 1

• Fluoroquinolone (ciprofloxacin) OR azithromycin, depending on local susceptibility patterns and travel history 1
• Ciprofloxacin 500 mg every 12 hours for 5-7 days for infectious diarrhea 4

For children requiring empiric therapy: 1

• Third-generation cephalosporin for infants <3 months or those with neurologic involvement 1
• Azithromycin for others, depending on local susceptibility and travel history 1

Critical Contraindication

AVOID antibiotics in patients with STEC O157 and other STEC producing Shiga toxin 2 (or if toxin genotype unknown), as antimicrobial therapy may increase risk of hemolytic uremic syndrome. 1 For non-O157 STEC that do not produce Shiga toxin 2, the evidence is insufficient to recommend for or against treatment. 1

Duration and Modification

Antimicrobial treatment should be modified or discontinued when a clinically plausible organism is identified. 1 This allows for targeted therapy and avoids unnecessary broad-spectrum coverage.

For infectious diarrhea, the usual duration is 5-7 days when antibiotics are indicated. 4

Common Pitfalls to Avoid

Do not use antimotility agents (loperamide) in suspected inflammatory diarrhea or diarrhea with fever, as this may worsen outcomes and increase risk of toxic megacolon. 1 Loperamide should be avoided at any age in these scenarios. 1

Do not give antibiotics to asymptomatic contacts of people with acute or persistent diarrhea, except asymptomatic carriers of Salmonella typhi who may be treated empirically to reduce transmission. 1

Avoid routine empiric antibiotics in persistent watery diarrhea lasting ≥14 days, as noninfectious causes (inflammatory bowel disease, irritable bowel syndrome, lactose intolerance) become more likely. 1

Special Populations

For immunocompromised patients with Clostridioides difficile colitis, specific testing should be performed in the event of diarrhea with or without acute abdomen. 1 Treatment should include appropriate antibiotics with early surgical consultation if systemic toxicity develops. 1

Pregnant women and children should receive azithromycin as the preferred agent when antibiotics are indicated. 3