Shigella Dysenteriae

Shigella Dysenteriae

Common Name: Shiga bacillus, Bacillary dysenteriae

General Characteristics

  • Short rods, 0.5 to 0.7 u in width and 2 to 3 u in length
  • Non encapsulated, non spore forming, non-motile
  • Stain well with aniline dyes; gram negative
  • Aerobic but facultatively anaerobic
  • On EMB agar plate, colonies are smooth, convex, colorless, smooth and round
  • On lactose medium; do not ferment lactose but do ferment sucrose with acid and no gas production
  • Lipopolysaccharide as endotoxin contribute to the irritation of the bowel wall
  • Heat-labile endotoxin affects both the gut and the central nervous system to paralyze the host
  • Destroyed easily by pasteurization and boiling
  • Inhabit intestinal tract of man
  • Causes shigellosis


  • An acute bacterial disease of the intestine characterized by diarrhea, accompanied by fever and vomiting, cramps and tenesmus.
  • In severe cases, the stools may contain blood, mucus and pus after a short incubation period of 1-3 days. Watery diarrhea is due to an exotoxin acting in the small intestine.
  • Always limited to the gastrointestinal tract; bloodstream invasion is quite rare.
  • Highly communicable; infective dose is less than 10 organisms

Mode of Transmission

  • Via personal contact with sick persons and carriers
  • Via fingers, feces, food, fomites and flies

Laboratory Diagnosis

  • Rectal swabbing under direct vision through a sigmoidoscope

Prevention and Control

  1. Isolation of sick persons.
  2. Detection and control of carriers.
  3. Examination of flies by use of baits, traps or insecticides.
  4. Sanitation and safeguarding of food supplies either by refrigeration or by covering foods on the table to avoid contamination.
  5. Effective disposal of sewage,
  6. Restoring water and chemical salts lost from the patient due to dehydration. Rehydration is accomplished by intravenous injections, administered preferably in a hospital.
  7. Overcoming the infection by use of drugs. Drugs are available to combat this disease and minimize its complications.
  8. The provision of adequate nourishment. The problem of nutrition is serious in the case of an infant. For older children, a high protein with low residue supplemented by vitamins is indicated.
  9. Immunization with vaccine is effective.


  • Chloramphenicol
  • Ampicillin
  • Tetracycline
  • Trimethoprim-sulfamethoxazole
  • Opiates should be avoided

Daisy Jane Antipuesto RN MN

Currently a Nursing Local Board Examination Reviewer. Subjects handled are Pediatric, Obstetric and Psychiatric Nursing. Previous work experiences include: Clinical instructor/lecturer, clinical coordinator (Level II), caregiver instructor/lecturer, NC2 examination reviewer and staff/clinic nurse. Areas of specialization: Emergency room, Orthopedic Ward and Delivery Room. Also an IELTS passer.

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