Treatment for Dysentery
Azithromycin is the first-line treatment for dysentery, given as either a single 1000 mg dose or 500 mg daily for 3 days, due to its superior efficacy against common dysentery pathogens and global fluoroquinolone resistance patterns. 1
Initial Empiric Treatment Approach
Start azithromycin immediately for all patients presenting with dysentery (bloody diarrhea with fever, abdominal cramping, and tenesmus), as it provides coverage for the most common bacterial causes including Shigella, Campylobacter, enteroinvasive E. coli, and other invasive pathogens. 2, 1
The recommended dosing is azithromycin 1000 mg as a single dose for dysentery, or alternatively 500 mg daily for 3 days if single-dose therapy is not feasible. 2, 1
Azithromycin has demonstrated superior clinical cure rates compared to fluoroquinolones in regions with high fluoroquinolone resistance (now exceeding 85-90% for Campylobacter in Southeast Asia and increasing worldwide). 2, 1
When to Consider Alternative Diagnoses
Attempt microscopic examination of fresh stool when possible to identify Entamoeba histolytica trophozoites before initiating treatment, as amebic dysentery is frequently misdiagnosed. 2, 3
Be careful to distinguish large white blood cells (nonspecific indicators of inflammation) from actual amebic trophozoites, which have characteristic morphology with ingested red blood cells. 2, 3
If microscopy is unavailable or negative for amoeba, treat empirically for bacterial dysentery with azithromycin. 2, 3
Only consider amebic dysentery if: (1) definite trophozoites are seen on microscopy, OR (2) the patient has failed two different appropriate antibiotics for bacterial dysentery. 2, 3
Treatment for Confirmed Amebic Dysentery
For confirmed E. histolytica infection, use metronidazole 750 mg orally three times daily for 5-10 days (or 30 mg/kg/day in children). 3, 4
Cure rates exceed 90% with metronidazole, and most patients respond within 72-96 hours. 3
Always follow metronidazole with 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, even if follow-up stool microscopy is negative. 3
Second-Line Options When Azithromycin Fails or Is Unavailable
If no clinical response occurs within 48 hours of azithromycin, switch to an alternative agent rather than continuing ineffective therapy. 1
Fluoroquinolones (ciprofloxacin 500 mg twice daily or levofloxacin 500 mg once daily for 3 days) may be used as second-line agents only in regions with documented low fluoroquinolone resistance, but should not be first-line due to widespread resistance. 2, 1
Cefixime or ceftriaxone are appropriate third-line alternatives when both azithromycin and fluoroquinolones have failed or resistance is documented. 1
Critical Pitfalls to Avoid
Never use rifaximin for dysentery, as it has documented treatment failure rates up to 50% with invasive pathogens and is only effective for noninvasive watery diarrhea. 2, 1
Do not assume fluoroquinolones are universally effective—regional resistance patterns must guide therapy, and in most settings azithromycin is now preferred globally. 2, 1
Avoid overdiagnosing amebic dysentery, which leads to inappropriate treatment and delays proper management of bacterial causes. 3
Do not use mass chemoprophylaxis for contacts, as it is not effective and diverts resources from more important control measures (water supply, sanitation, prompt treatment). 2
Adjunctive Therapy
Loperamide (4 mg initial dose, then 2 mg after each loose stool, maximum 16 mg/24 hours) may be combined with antibiotic therapy to reduce symptom duration and severity, but should be used cautiously in severe dysentery. 2
Ensure adequate hydration with oral or intravenous fluids depending on severity of dehydration. 5