What is the management of dysentery?

Dysentery: Definition and Management

Definition

Dysentery is defined as diarrhea with visible blood, mucus, or pus in the stool, typically caused by invasive bacterial pathogens, most commonly Shigella species, or less frequently by Entamoeba histolytica. 1

• The syndrome indicates invasion of the intestinal mucosa and requires different management than simple watery diarrhea 1
• Large white blood cells in stool are nonspecific indicators of dysentery but must be distinguished from amebic trophozoites 1

Management Algorithm

Step 1: Initial Assessment and Diagnostic Approach

When microscopy is available, examine stool specimens to identify Entamoeba histolytica trophozoites before initiating treatment, as amebic dysentery is frequently misdiagnosed. 1, 2

• If microscopy is unavailable or definite trophozoites are not seen, treat initially for bacterial dysentery (shigellosis) 1, 2
• Only consider amebiasis if two different antibiotics for shigellosis have failed 1, 2

Step 2: First-Line Antibiotic Treatment for Bacterial Dysentery

Azithromycin is the preferred first-line antibiotic for dysentery, given as either a single 1000 mg dose or 500 mg daily for 3 days. 1, 3, 4

This recommendation is based on:

• Superior efficacy against fluoroquinolone-resistant Campylobacter, which now exceeds 90% resistance in many regions including Southeast Asia 1
• Excellent coverage for Shigella species, enteroinvasive E. coli, Aeromonas, Plesiomonas, and Yersinia enterocolitica 1, 3
• WHO guidelines demonstrating 82% reduction in clinical failure rates with current recommended antibiotics including azithromycin 1

Pediatric dosing: 10 mg/kg on day 1, then 5 mg/kg daily for days 2-5 (or single dose regimen based on weight) 1

Step 3: Alternative Antibiotics

If azithromycin is unavailable or contraindicated, use ciprofloxacin 500 mg twice daily for 3 days (or 750 mg single dose for non-dysenteric cases). 1, 4

• Fluoroquinolones remain effective for non-dysenteric severe diarrhea but have declining efficacy for dysentery due to resistance 1
• Pediatric ciprofloxacin dosing: 15 mg/kg every 12 hours for 3 days 1, 5
• Cefixime is an appropriate second-line alternative, particularly in regions with high fluoroquinolone resistance 1, 6

Step 4: Adjunctive Loperamide Use

Loperamide can be safely combined with antibiotics in dysentery to reduce symptom duration and number of stools, contrary to traditional teaching. 1, 7

• Dosing: 4 mg initial dose, then 2 mg after each loose stool, maximum 16 mg per 24 hours 1, 3
• In adults with Shigella dysentery treated with ciprofloxacin, loperamide reduced median diarrhea duration from 42 to 19 hours 7
• Critical caveat: Discontinue loperamide if symptoms worsen or fever develops 1

Step 5: Treatment Failure Protocol

If no clinical response occurs within 48 hours, change to a different antibiotic class. 1

• After failure of two different antibiotics for shigellosis, refer for stool microscopy and consider amebic dysentery 1, 2
• Resistant shigellosis remains more likely than amebiasis even after initial treatment failure 1

Step 6: Treatment for Confirmed Amebic Dysentery

For confirmed amebiasis (trophozoites visualized), use metronidazole 750 mg orally three times daily for 5-10 days. 2, 8

• Pediatric dosing: 30 mg/kg/day divided into three doses for 5-10 days 2
• Cure rates exceed 90%, with most patients responding within 72-96 hours 2
• Essential follow-up: After completing metronidazole, always add a luminal amebicide (diloxanide furoate 500 mg three times daily for 10 days OR paromomycin 30 mg/kg/day in 3 divided doses for 10 days) to prevent relapse 2

Critical Pitfalls to Avoid

• Do not use rifaximin for dysentery—it has documented treatment failures in up to 50% of invasive diarrhea cases 1, 3
• Do not continue loperamide if dysentery worsens despite very low rates of adverse effects in clinical practice 1
• Do not treat for amebiasis without microscopic confirmation unless bacterial treatments have definitively failed, as overdiagnosis leads to inappropriate management 1, 2
• Do not use ampicillin or TMP-SMX as first-line therapy—resistance rates are extremely high worldwide 1
• Do not forget luminal amebicide after metronidazole—failure to do so results in treatment failure and relapse 2

Geographic Considerations

In Southeast Asia and India, use azithromycin empirically as first-line due to fluoroquinolone resistance exceeding 90% for Campylobacter. 1

• Resistance to nalidixic acid and ciprofloxacin in Asia-Africa is 33.6% and 5.0% respectively, compared to 3.2% and 0.3% in Europe-America 1
• Resistance rates are higher in children than adults 1