What is the baseline drug for treating dysentery?

Azithromycin is the First-Line Drug for Bacillary Dysentery

Azithromycin should be used as the first-line treatment for bacillary dysentery, with a dose of 1000 mg as a single dose or 500 mg daily for 3 days, based on current guideline recommendations that prioritize this agent due to widespread fluoroquinolone resistance and superior safety profile. 1

Treatment Algorithm for Bacillary Dysentery

First-Line Therapy

• Azithromycin is recommended as the preferred agent for all cases of dysentery regardless of geographic region, based on high clinical and bacteriological cure rates and the fact that global fluoroquinolone resistance now exceeds 85% for common dysentery pathogens in many regions. 1
• The recommended dosing is 1000 mg as a single dose or 500 mg daily for 3 days. 1

Second-Line Options When Azithromycin Is Unavailable

• Ciprofloxacin can be used as a second-line option only in regions with documented low fluoroquinolone resistance, but should not be first-line due to increasing resistance patterns. 1
• Ciprofloxacin demonstrated effectiveness in treating Shigella dysenteriae type 1 during epidemics, with an 85.6% clinical cure rate using 1 g daily in two doses for 5 days for adults. 2
• For Shigella species other than S. dysenteriae type 1, single-dose ciprofloxacin (1 gram) was effective, but for S. dysenteriae type 1 infections, treatment failure occurred in 40% of patients receiving single-dose therapy compared to 0% with 5-day therapy. 3

Third-Line Alternatives

• Cefixime or ceftriaxone are appropriate third-line alternatives when azithromycin and fluoroquinolones have failed or resistance is documented. 1

Critical Diagnostic Distinction: Bacterial vs. Amebic Dysentery

When to Suspect Amebic Dysentery

• Microscopic examination of fresh stool should be performed to identify Entamoeba histolytica trophozoites when possible. 1
• Empirical treatment for bacterial dysentery should be initiated if microscopy is unavailable or negative for amoeba. 1
• Consider amebic treatment only if microscopy shows definite trophozoites OR two different antibiotics for shigellosis have failed. 1, 4
• Amebic dysentery is frequently misdiagnosed, and the tendency to overdiagnose amebiasis leads to inappropriate treatment and delays proper management of bacterial dysentery. 4

Treatment for Confirmed Amebic Dysentery

• Metronidazole 750 mg orally three times daily for 5-10 days is the first-line therapy for amebic dysentery, with cure rates exceeding 90% and most patients responding within 72-96 hours. 4, 5
• For children, the recommended dose is 30 mg/kg/day for 5-10 days. 4
• 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) must follow metronidazole to prevent relapse. 4

Common Pitfalls to Avoid

Fluoroquinolone Overreliance

• Do not assume fluoroquinolones are still universally effective, as regional resistance patterns must guide therapy, and azithromycin is now preferred globally. 1
• Quinolones were previously the empirical antimicrobials of choice for dysentery, but increasing bacterial resistance is compromising their use. 6

Inappropriate Use of Rifaximin

• Rifaximin should not be used for dysentery due to documented treatment failures in up to 50% of cases with invasive pathogens. 1

Delayed Treatment Changes

• Switch to an alternative agent rather than continuing ineffective therapy if no clinical response is seen within 48 hours. 1

Antimotility Agent Use

• Loperamide combined with ciprofloxacin shortened duration of diarrhea in Shigella dysentery (median 19 hours vs. 42 hours) without adverse effects in adults. 7
• However, antimotility agents are generally contraindicated in dysentery due to theoretical concerns about prolonging infection. 8

Supporting Evidence for Antibiotic Use

• Antibiotics reduce the duration of Shigella dysentery and episodes of diarrhea at follow-up compared to no treatment (furazolidone RR 0.21, cotrimoxazole RR 0.30). 9
• All antibiotics studied for shigellosis were safe, though there was inadequate evidence regarding their role in preventing relapses. 9
• Regularly updated local or regional antibiotic sensitivity patterns are required to guide empiric therapy for different Shigella species and strains. 9