Bacillus Anthrax:Clinical manifestation, Diagnosis and treatment

Introduction:

• Anthrax is a zoonoses
• Occurs primarily in herbivores.
• “Man is relatively resistant to infection with B. anthrax”
• Aerosolized anthrax — 10,000 spores required to produce lethal disease. 
• Few as one to three spores may be adequate to cause disease in some setting
• According to The Workmen’s Compensation Act, 1923, Anthrax is considered an occupational disease

Routes

• Humans become infected when B. anthracis spores are introduced into the body by the following routes:
• Contact with infected animals or contaminated animal products
• Insect bites
• Ingestion
• Inhalation
• In humans anthrax occurs in following forms

1. Cutaneous anthrax

• Cutaneous anthrax is most common.
• It follows the entry of infection through the skin.
• The whole area is congested and edematous
• The lesion starts as macule
• Progress through papular and vesicular or pustular stages
• Formation of an ulcer with a blackened necrotic eschar.
• The lesion is painless.
• It is called malignant pustule.
• Hide porter’s disease.
• Caused by contact with contaminated hair, wool, hides or products
• Satellite nodule around inguinal region
• Cutaneous anthrax generally resolves spontaneously
• But 10-20% of untreated patients may develop septicemia.
• 2. Pulmonary anthrax
• Woolsorters’ disease
• Occupational hazard for people who sorted wool
• Most dangerous form of inhalational anthrax
• It causes hemorrhagic pneumonia.
• 3. Intestinal anthrax
• It is rare.

Laboratory Diagnosis 

• Mc-Fadyean’s Reaction 
• Blood films containing anthrax bacilli are stained with polychrome methylene blue stain for few seconds
• Examined under microscope
• Amorphous purplish material  is noticed around bacilli.
• This represents the capsular material and is characteristic of anthrax bacilli. 
• Culture Characteristics of Bacillus anthracis 
• On agar plate: Frosted glass appearance
• On gelatin stab culture: Inverted fir tree appearance
• Immunofluorescent microscopy
• confirm identification.
• Ascoli’s thermoprecipitin /Elek’s gel precipitation test
• Sample is putrid,
• demonstrate anthrax antigen in tissue extract. .
• Antibody by immunoassays
• Confirm diagnosis.

Treatment

• Penicillin is drug of choice.
• In penicillin allergy →
• ciprofloxacin, erythromycin, tetracyline or chloramphenicol.