Dysentriae

Clinical syndrome characterized by frequent passage of small-volume stools containing blood and/or mucus

Aetiology

Bacillary Dysentery

  • Shigella spp. (most common)
  • Campylobacter jejuni
  • Salmonella (non-typhoidal)
  • Enteroinvasive E. coli (EIEC)

Amoebic Dysentery

  • Entamoeba histolytica

Pathophysiology

Bacillary Dysentery

  • Ingestion of invasive bacteria
  • Bacterial invasion of colonic epithelium
  • Mucosal inflammation → ulceration
  • Exudation of blood, mucus, and pus into stool

Amoebic Dysentery

  • Ingestion of cysts
  • Excystation in intestine → trophozoites
  • Flask-shaped ulcers in colon
  • Hematogenous spread may cause liver abscess

Clinical Presentation

Intestinal Features

  • Frequent loose stools with blood and mucus
  • Tenesmus
  • Lower abdominal pain or cramping
  • Urgency

Systemic Features

  • Fever (high in bacillary, mild in amoebic)
  • Malaise
  • Dehydration (variable)

Differentiating Features

Feature
Bacillary
Amoebic
Onset
Acute
Subacute
Fever
High
Mild or absent
Stool frequency
Very frequent >10x/day, small volume
Fewer stools, high volume
Blood in stool
Bright red, mixed
Darker blood
Tenesmus
Prominent
Mild
Toxicity
Common
Rare

Investigations

Laboratory Findings

  • Leukocytosis
  • Thrombocytopenia
  • Elevated liver enzymes (bilirubin disproportionately high)
  • Elevated creatinine and urea
  • Elevated CK

Specific Diagnostic Tests

Serology
  • Microscopic Agglutination Test (MAT) – gold standard
  • ELISA (IgM)
Molecular Tests
  • PCR (early phase)
Culture
  • Blood & CSF (early phase, within 10 days)
  • Urine (late phase, after 7 days of onset)
  • Slow-growing and rarely used clinically

Management

General Management (ALL Patients)

  • Oral rehydration solution (ORS)
  • IV fluids if severe dehydration
  • Nutritional support
  • Zinc supplementation (children)

Specific Therapy

Bacillary Dysentery
  • Antibiotics shorten illness and reduce transmission
  • Choice depends on local resistance patterns
  • Avoid antimotility agents
Drug
Dose
Route
Duration
Indication / Notes
Ciprofloxacin
500 mg twice daily
PO
3 days
First-line in adults
Ciprofloxacin
400 mg twice daily
IV
3 days
Severe illness
Azithromycin
500 mg once daily
PO
3 days
Preferred in children & pregnancy
Ceftriaxone
1–2 g once daily
IV
3–5 days
Severe disease / resistance
Amoebic Dysentery
  • Two-step therapy is mandatory
      1. Tissue amoebicide
      1. Luminal amoebicide
      Tissue Amoebicides (First Step)
      Drug
      Dose
      Route
      Duration
      Notes
      Metronidazole
      750 mg three times daily
      PO
      7–10 days
      First-line
      Metronidazole
      500 mg q8h
      IV
      7–10 days
      If oral not tolerated
      Tinidazole
      2 g once daily
      PO
      3–5 days
      Better tolerance
      Luminal Amoebicides (Second Step)
      Drug
      Dose
      Route
      Duration
      Diloxanide furoate
      500 mg 3x1
      PO
      10 days
      Paromomycin
      25–30 mg/kg/day in 3 doses
      PO
      7 days
      Iodoquinol
      650 mg 3x1
      PO
      20 days

Antimotility Drugs

🚫 Contraindicated in dysentery due to risk of:
  • Toxic megacolon
  • Prolonged infection