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  • Spore forming , GPB, O2 , Gram variable
  • Motile by peritrichous flagella, exception: B. anthracis  
A.  Anthracis :
  1. First pathogenic bacterium to be observed under microscope
  2. First bacterium isolated in pure culture
  3. First communicable disease shown to transmit by inoculation of infected blood.
  4. First used for preparation of attenuated vaccine- Pasteur’s vaccine-nontoxigenic strain
  5. Recently used for biological warfare as spores enclosed in envelopes
  6. Capsule seen in tissue ; polypeptide (d-glutamic acid polymer), in culture (10 -25% CO2 , added bicarbonate, starch , serum , charcoal, albumin)
  7. " Bamboo stick" appearance in culture
  8. Spores in culture, in soil, not in animals; central, non bulging
Sporulation encouraged by :
  1. Distilled water
  2. 2% NaCl
  3. Growth in oxalated agar
  4. O2 required for sporulation
    1. Mac Fadyean's reaction: polychrome methylene blue on blood film for demonstrating the capsule.
    2. " Medusa head" appearance on solid medium
    3. " Inverted fir tree" appearance in gelatin stab culture.
    4. " String of pearl" appearance in culture medium with penicillin
    5. Selective medium: PLET (polymyxin, lysozyme, EDTA, thallous acetate) medium and Phenyl ethyl alcohol Agar.
    6. Duckering: Destruction of spores in animal products by using formaldehyde 2% at 30-40°C for 20 minutes for wool; 0.25% at 60°C for 6 hrs for animal hair
Pathogenicity :
  1. In nature, anthrax is primarily a disease of cattle & sheep, less often of horse & swines. 
Virulence factors :
  1. Capsule : Inhibits phagocytosis. Plasmid mediated
  2. Toxin:Plasmid mediated Complex of 3 fractions which is toxic only when all together & not alone
    1. EF (edema factor or Factor I) : adenyl cyclase which is activated inside the cell: intracellular accumulation of cAMP.
    2. LF (lethal factor or Factor III) : Mechanism unknown, death of cell.
    3. PA (protective antigen or Factor II) : Binding to target cell. 
Anthrax is a Zoonosis-acquired by ingestion of infected meat/inhalation of spores/handling infected animal tissues through small cuts or abrasions

  1. Cutaneous : malignant pustule / hide porter's disease. Most common type.Can recover spontaneously
  2. Pulmonary : Wool sorter's disease.
  3. Intestinal- hemorrhagic enteritis
    1. All 3 forms can lead to fatal septicemia
    2. Infection in humans : permanent immunity       
1.  Diagnosis
  1. Microscopy, culture, animal inoculation
  2. Ascoli thermoprecipitin test: demonstration of anthrax antigen in tissue extracts.
  3. Serological tests: ELISA  
2.  Prophylaxis :
  1. Sterne's vaccine: spores of avirulent noncapsulated strain
  2. Mazucchi vaccine: prepared from spores       
  3. Alum precipitated toxoid from PA: for human use                                                     
Characteristic of Bacillus cereus food poisoning is (AIIMS 2010)
A. presence of Fever       
B. presence of Pain abdomen       
C. Absence of Vomiting     
D. absence of Diarrhea

Ans- B.

B. Bacillus cereus
2 types of food borne disease
  1. Type 1 : Diarrheal type
    1. Enterotoxin (similar to Labile Toxin )
    2. Wide range of foods
    3. Diarrhoea & abdominal pain 8-16 hrs after ingestion of food, vomiting is rare
    4. Serotypes : 2 , 6 , 8, 9 , 10, 12
2.  Type 2 : Emetic type     
  1. Emetic toxin (similar to staphylococcal enterotoxin)
  2. Cooked fried rice
  3. Acute nausea, vomiting and pain abdomen 1-5hrs after meal, diarrhea not common
  4. Serotypes : 1, 3 ,5

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