What is the recommended treatment for a patient presenting with bacterial diarrhoea?

Treatment of Bacterial Diarrhoea

Antibiotics are NOT routinely indicated for bacterial diarrhoea; rehydration is the cornerstone of treatment, with antimicrobials reserved only for specific high-risk groups including infants <3 months, patients with bacillary dysentery (Shigella), recent international travelers with fever ≥38.5°C, immunocompromised patients with bloody diarrhoea, and suspected enteric fever. 1, 2

Initial Assessment and Risk Stratification

Determine if antibiotics are indicated by evaluating:

• Age: Infants <3 months with suspected bacterial etiology require empiric treatment 1, 2
• Clinical presentation: Fever ≥38.5°C, bloody diarrhoea, signs of sepsis, or bacillary dysentery warrant antibiotics 1, 2
• Travel history: Recent international travel with fever suggests empiric treatment 2
• Immune status: Immunocompromised patients with severe illness and bloody diarrhoea require antibiotics 1, 2
• Suspected pathogen: Enteric fever with sepsis requires immediate empiric treatment after obtaining cultures 1, 2

Critical Contraindication

NEVER give antibiotics for STEC O157:H7 or Shiga toxin 2-producing E. coli, as this significantly increases the risk of hemolytic uremic syndrome (HUS). 1, 2 This is a moderate-quality evidence recommendation that takes absolute priority over empiric treatment considerations. 1

Antibiotic Selection When Indicated

For Adults:

• First-line: Azithromycin (single 1-gram dose or 500 mg daily for 3 days) 2, 3
• Second-line: Fluoroquinolones (ciprofloxacin 750 mg single dose or 500 mg twice daily for 3 days) only if azithromycin unavailable and in regions with documented low resistance 2, 3
• Rationale: Fluoroquinolone-resistant Campylobacter now exceeds 90% in many regions including Thailand and India, making azithromycin superior 2, 3

For Children:

• Infants <3 months: Third-generation cephalosporin (ceftriaxone) is the preferred agent 1, 2
• Children >3 months: Azithromycin based on local susceptibility patterns and travel history 1, 2

Pathogen-Specific Treatment:

• Shigella: Azithromycin 500 mg twice daily for 3 days (first-line) or ceftriaxone 100 mg/kg/day 2
• Campylobacter: Azithromycin 500 mg daily for 3 days due to high fluoroquinolone resistance 2
• Cholera: Azithromycin single dose is superior to ciprofloxacin, reducing diarrhoea duration by more than 1 day 2
• Non-typhoidal Salmonella: Treat ONLY high-risk patients (severe infection, age <6 months or >50 years, immunocompromised, prosthetics, valvular heart disease) 2

Rehydration Protocol (Essential for ALL Patients)

• Mild to moderate dehydration: Reduced osmolarity oral rehydration solution (ORS) containing 50-90 mEq/L sodium 1, 2
• Replace ongoing losses: 10 mL/kg of ORS for each watery stool 4
• Severe dehydration: Intravenous fluids for shock, altered mental status, or ileus 2
• Continue normal food intake guided by appetite with small, light meals; avoid fatty, heavy, spicy foods and caffeine 4

When NOT to Use Antibiotics

• Acute watery diarrhoea in immunocompetent patients without travel history 1, 2
• Asymptomatic contacts of patients with bloody or watery diarrhoea 1, 2
• Confirmed or suspected STEC/EHEC infection (obtain stool culture and Shiga toxin testing first) 1, 2
• Uncomplicated watery diarrhoea without fever or blood 2

Diagnostic Workup Before Treatment

• Obtain stool culture immediately if considering antibiotics, especially for bloody diarrhoea 1
• Check for Shiga toxin before starting antibiotics in bloody diarrhoea cases 2
• Assess hydration status: Examine skin turgor, capillary refill, mental status, mucous membranes 1

Common Pitfalls to Avoid

• Never neglect rehydration while focusing on antimicrobials, as dehydration is the primary cause of morbidity and mortality 2, 4
• Never give antibiotics empirically for bloody diarrhoea without ruling out STEC first 2
• Avoid overuse of fluoroquinolones, which should only be used when no more appropriate options are available due to FDA safety warnings 2
• Do not treat non-typhoidal Salmonella routinely; only treat high-risk patients 2

Reassessment and Follow-Up

• If symptoms persist >14 days: Consider non-infectious causes (inflammatory bowel disease, lactose intolerance, microscopic colitis) 1, 4
• If no response within 48-72 hours: Reassess for antibiotic resistance, fluid and electrolyte imbalances, or inadequate rehydration 2, 4
• Modify or discontinue antimicrobials when a clinically plausible organism is identified 2