Write a prescription for an adult with moderate-to-severe acute diarrhoea and fever, suspected bacterial gastroenteritis.

Prescription for Adult with Moderate-to-Severe Acute Diarrhea and Fever (Suspected Bacterial Gastroenteritis)

For an adult with moderate-to-severe acute diarrhea and fever suggestive of bacterial gastroenteritis, prescribe either ciprofloxacin 500 mg orally every 12 hours for 5-7 days OR azithromycin 500 mg orally once daily for 3 days, with the choice depending on local resistance patterns and recent travel history. 1

Antibiotic Selection Algorithm

First-line empiric therapy:

• Ciprofloxacin 500 mg PO every 12 hours for 5-7 days if the patient has NOT recently traveled internationally and local fluoroquinolone resistance is low 1, 2

• Azithromycin 500 mg PO once daily for 3 days if the patient has recently traveled internationally (especially to South/Southeast Asia where fluoroquinolone resistance is high) OR if local resistance patterns favor macrolides 1

The 2017 IDSA guidelines strongly recommend empiric antimicrobial therapy for adults with fever documented in a medical setting, abdominal pain, and bloody diarrhea suggestive of bacillary dysentery, or for those with recent international travel and temperature ≥38.5°C 1

Additional Prescription Components

Rehydration therapy (essential):

• Oral rehydration solution (ORS) to drink liberally until clinical dehydration resolves 1
• If unable to tolerate oral intake or signs of severe dehydration present, arrange for IV lactated Ringer's or normal saline 1

Symptomatic relief (optional, use cautiously):

• Loperamide 4 mg initially, then 2 mg after each loose stool (maximum 16 mg/day) may be added ONLY if diarrhea is non-bloody and fever is mild 1
• AVOID loperamide if bloody diarrhea or high fever present due to risk of toxic megacolon 1

Critical Caveats and Pitfalls

Do NOT prescribe antibiotics if:

• STEC O157 or Shiga toxin-producing E. coli is suspected (can precipitate hemolytic uremic syndrome) 1
• Diarrhea is watery without fever or blood (likely viral; antibiotics not indicated) 1

When to escalate care:

• Signs of sepsis, altered mental status, or severe dehydration require immediate IV fluids and possible hospitalization 1
• If symptoms persist >7 days despite treatment, obtain stool cultures and consider non-infectious causes 1

Resistance considerations:

• Fluoroquinolones remain first-line for empiric treatment of febrile dysentery when bacterial resistance is limited 1
• However, increasing ciprofloxacin resistance in Campylobacter and Salmonella (particularly from South/Southeast Asia) makes azithromycin preferable for travelers from these regions 1
• Co-trimoxazole is no longer recommended due to widespread resistance 1

Monitoring and Follow-up

• Symptoms should improve within 24-48 hours of starting antibiotics 1
• Continue antibiotics for full course even if symptoms resolve earlier 2
• Return immediately if bloody stools worsen, fever persists >72 hours, or signs of dehydration develop 1
• Stool cultures are NOT routinely needed unless symptoms persist, patient is immunocompromised, or outbreak is suspected 1, 3