The document discusses several species of Bacillus bacteria including B. anthracis, B. cereus, and common characteristics. B. anthracis causes anthrax through three routes - cutaneous, inhalational, and ingestional. The pathogenicity of anthrax depends on the capsule and toxins produced. B. cereus commonly causes two types of food poisoning. Control and treatment of anthrax and food poisoning are also covered.

1. Bacillus
Key points
 Commonenvironmental Gram-positiverods
 Bacillus anthracis causescutaneous,inhalational andingestional anthrax
 The pathogenicityof anthrax dependsonthe capsule andtoxins
 Antibiotictreatmenttothe inhalational and ingestionalanthrax isdifficult
 Bacillus anthracis Sterne stain(toxic- negative) isusedasan animal vaccine
 Bacillus cereus commonlycausesfoodpoisoning
 A Bacillus cereus stainwithanthrax toxingenescausesanthrax-like diseases
Bacillus
 Large
 Spore forming
 Gram-positive
 Bacilli whoformschains
 Commonenvironmental organisms
 A frequentcontaminantof laboratorymediaandspecimens
 Can growaerobicallyaswell asanaerobically
 Bacillus speciescancause pathogenesisunderspecial circumstances asin
immunocompromisedpatients.
Common pathogens
 Bacillus anthracis - causesanthrax
 Bacillus cereus - causesfoodpoisoning
Bacillus anthracis
 Large colonies
 Zoonotic
 Non-motile
 Spore forming
o Heat stable (12- 45o
C)
o Optimum35o
C
o Oval
o Refractile
o Centre inposition
o Form readily
 Grows onall ordinarymedia
o as typical colonies
o with‘ground-glass’surfaceappearance
o wavymargin withsmall projections
o ‘medusa- head’appearance
 Capsulated
 Aerobicandanaerobicgrowth

2. Pathogenesis
 Zoonoticdisease
 Transmissiblesecondarilytohumans
 Farm animalslike sheep,cattle canbe affected
 Sporesare the infectivestage
 From the site tothe regional lymphnodes
 Sporesgerminate
 Bacteriamultiply
 Bacteraemia
 Septicaemia
 Death
Virulence factors
 Capsule
o Antiphagocyticeffect
 Exotoxins - damage to the host
o Oedemafactor - local swelling(adenylyl cyclase )
o Lethal factor - macrophage lysis(metalloprotease)
Anthrax
 Cutaneousanthrax - throughskinabrasions
 Inhalational anthrax - inhaledspores
 Ingestional anthrax - ingestedspores(rare)
Cutaneous anthrax
 Throughskinabrasions
 Malignantpustules
 Coagulative necrosisof the centre
 Eschar (dark) inthe centre
 Oedematousanderythematousring
 Lymphatics
 Septicaemia
Inhalational anthrax
 Most acute type
 Inhalationof spores
 Inflammation
 Haemorrhages
 Septicaemia
 Shock
Ingestional anthrax
 Ingestionof spores
 Inflammation
 Haemorrhagicdiarrhoea
 Septicaemia

3.  Shock
Collection of specimens
 Exudate
 Pus
 Sputum
 Blood
Lab diagnosis
 Gram stain large rods inchainforms
 Culture greyish,ground-glass,colonies,medusaheadlookinbloodagar
Treatment
 Drug of choice - penicillin
 Otherdrugs - erythromycin,tetracyclins
 Prophylaxis - ciprofloxacin
Bacillus cereus
 Causesacute gastroenteritis
 Produce enterotoxins
 Foodpoisoning
Types of food poisoning
 Vomitingtype
o Early onset
o Within6 hours of ingestion
o By preformedtoxin
o Heat andacid stable toxin
Eg- Chinese friedrice
 Diarrhoeal type
o Late onset
o After8-48 hours
o Enterotoxin
o Heat labile
o Formedwithinthe intestine
o Shigella, E.coli, Salmonella type diarrhoea
Eg- cookedmeat,soup,sauces
Control
 If refrigeratingforalongtime keepthe foodbelow 4o
C