Bacillus Anthrax:Clinical manifestation, Diagnosis and treatment

The typical lesion of cutaneous anthrax is a painless ulcer with a black eschar (crust, scab) with local edema. The lesion is called a malignant pustule.

Must know:

• B. anthracis is a large “box car–like” gram-positive rod.
• Its antiphagocytic capsule is composed of D-glutamate. (This is unique—capsules of other bacteria are polysaccharides.)
• It is non motile, whereas other members of the genus are motile.
• Anthrax toxin is encoded on one plasmid, and the polyglutamate capsule is encoded on a different plasmid.
• Pulmonary anthrax, also known as “woolsorter’s disease”.

Ref: Levinson W. (2012). Chapter 17. Gram-Positive Rods. In W. Levinson (Ed), Review of Medical Microbiology & Immunology, 12e.

Ans. is ‘a’ i.e., M’ Fadyean reaction shows capsule; ‘b’ i.e., Humans are usually resistant to infection; ‘c’ i.e., Less than 100 spores can cause pulmonary infection 

.  M’ Fadyean’s reaction represents the capsular material and is characteristic of the anthrax bacillus.

.  “Man is relatively resistant to infection with B. anthracis”. – Green wood 16^th/e 226

.   In animal studies, it has been shown that aerosolized anthrax — 10,000 spores required to produce lethal disease. However, it has been suggested that as few as one to three spores may be adequate to cause disease in some setting. – Harrison 17^thie 1344

.   Spores are of same width as the bacillary body so that they do not cause bulging of the vegetative cell (in contrast the clostridia have bulging spores).

.  For laboratory diagnosis, specimens to be examined are fluid or pus from a local lesion, blood or sputum. Stained smears often show chains of large gram positive rods.

Ans. is ‘c’ i.e., Cutaneous type is rare nowadays 

• Anthrax is a zoonoses caused by Bacillus anthracis, that occurs primarily in herbivores.
• Humans become infected when B. anthracis spores are introduced into the body by the following routes:

a)         Contact with infected animals or contaminated animal products

b)       Insect bites

c)       Ingestion

d)       Inhalation

1. Cutaneous anthrax

• Cutaneous anthrax is most common.
• It follows the entry of infection through the skin.
• The lesion starts as macule then typically progress through papular and vesicular or pustular stages to the formation of an ulcer with a blackened necrotic eschar.
• The lesion is painless.*
• Its called malignant pustule.
• It is also known as Hide porter’s disease.

2. Pulmonary anthrax

• It is called Wool sorter’s disease.*
• It follows inhalation of dust from infected wool.
• It causes hemorrhagic pneumonia.

3. Intestinal anthrax

• It is rare.

Ans. is ‘b’ i.e., Diphtheria 

Ans. is ‘a’ i.e., Extremely painful 

Cutaneous anthrax is painless.

Ans. is ‘a’ i.e., Pneumonic form of Anthrax 

Ans. is ‘d’ i.e., All of the above

• Vaccines for chicken cholera, rabies, and anthrax was developed by pasteur

Ans. is ‘c’ i.e., Cutaneous type 

Ans. is ‘d’ i.e., Anthrax 

Ans. a. Cutaneous anthrax

Anthrax

• Anthrax is a zoonoses, caused by Bacillus anthracis°, that occurs primarily in herbivores

Routes of Infection:

• 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°

Three major clinical forms in Humans:

• Cutaneous° (MC)
• Gastrointestinal (rare)
• Inhalational or pulmonary (it causes hemorrhagic pneumonia)

Woolsorters’ disease

• Occupational hazard for people who sorted wool°
• Most dangerous form of inhalational anthrax

Hide porter’s disease

• Caused by contact with contaminated hair, wool, hides or products

Malignant pustule

• Commonly seen in head and neck°
• Eschar stage that appears 2-6 days after the hemorrhagic vesicle dries to become a depressed black scab° surrounded by redness

Diagnosis:

• Presumptive diagnosis of the anthrax is made by staining it with polychrome methylene blue stain, called as Mc-Fadyean’s reaction

Anthrax

Mc-Fadyean’s Reaction

• When blood films containing anthrax bacilli are stained with polychrome methylene blue stain for few seconds and examined under microscope, an amorphous purplish material° is noticed around bacilli.
• This represents the capsular material and is characteristic of anthrax bacilliQ

Culture Characteristics of Bacillus anthracis

• On agar plate: Frosted glass appearance°
• On gelatin stab culture: Inverted fir tree appearance°

Ans. b. Anthrax

Ans. is ‘b’ i.e., Rickettsial infection 

Antibacterial spectrum of Penicillin G (Benzvl

• PnG is a narrow spectrum antibiotic
• Activity is limited primary to gram positive bacteria (and few others).
• Amongst gram negative organisms, penicillin has activity against gonococci, meningococci, few Ecoli & proteus. 
• Majority of gram negative bacilli are insensitive.
• M. Tuberculosis, Ricketsiae, chlamydia, protozoa, fungi and viruses are totally insensitive to penicillin G.

Penicillin G is the DOC for (Laurence 9thie 218. Katzung 7301 

Ans. is ‘d’ i.e., Schistosomiasis 

Zoonoses

• Zoonoses are diseases and infections which are naturally transmitted between vertebrate animal and man. 
• The zoonoses may be classified according to the direction of transmission of disease : ‑

l. Anthropozoonoses

• Infection is transmitted to man from lower vertebrate animals.
• Examples -4 Rabies, plague, hydatid disease, anthrax, trichinosis.

2. Zoonthroponoses

• Infection is transmitted from man to lower vertebrate animals
• Examples → Human tuberculosis in cattle

3. Amphixenoses

• Infection is maintained in both man and lower vertebrate animals that may be transmitted in either direction.
• Examples T cruzi, S. japonicum.