BACILLUS ANTHRAX

Dr.Baha ,Hamdi AL-AmiediPh. D.Microbiology

BACILLUS

ANTHRACIS

BACILLUS ANTHRAXDr.Baha ,Hamdi AL-Amiedi

Ph. D.Microbiology

Bacillus:General characters

Anthrax is a zoonotic disease (could be transferred from animals to humans) caused by the spore-producing bacterium Bacillus anthracis.

It is Gram positive ,non-motile, rod shape, spore bearing, Aerobic bacilli occurring in chains. Two pathogenic species :

Bacillus anthracis: causes Anthrax disease

Bacillus cereus : causes (food poisoning )

gastroenteritis

Bacillus anthracis

Causces anthrax, a disease especially prevalent in goats, sheep, and cattle

It is a spore former, spores is very stable, resistant to dry , heat, Ultraviolent light play an important role in transmission to human & cause infection, they can survive in soil or skin of animals for years. It is unique in that it is only bacterium with

capsule composed protein(poly-D-glutamic acid )

Clinical manifestation

Bacillus anthracis causes three different

forms of anthrax:

1-cutaneous anthrax

2-Pulmonary anthrax

3-gastrointestinal anthrax

Cutaneous anthrax

the most common naturally occurring

form

of the disease and is characterized by

local inflamatory necrotic lesion (eschar)

at the site of inoculation transmitted

through contact with spores in the

infected animals or animal products

(wool, hair, bone)

Cutaneous Anthrax

PULMONARY ANTHRAX

Also called( Woolsorters disease) : is a

highly fatal form of disease

characterized by rapid and massive

edema in the cheast followed by

cardiovascular shock and death

transmitted occurs when spores

inhaling from infected animals or animals

products

PULMONARY ANTHRAX

Inhalation of the dust or

filaments of wool from

infected animals,

particularly in wool

factories ( wool sorter’s

disease)

Haemotogenous spread –

50% meningitis

Chest X-ray

Chest X-rays is advised as an initial method of

inhalation anthrax detection, but it is

sometimes not useful for patients without

symptoms.

Find a widened mediastinum and pleural

effusion.

At day 1 At day 3

Gastroingtestinal anthrax

Which result from ingestion of spores ,

is very rare but highly fatal

transmitted when spores from infected

animals or animals products these spores

are ingested

INTESTINAL ANTHRAX

Consumption of improperly cooked

infected meat.

Causes violent enteritis with bloody

diarrhoea

All clinical conditions lead to septicaemic anthrax if

not treated early – Highly fatal!!!

Pathogenesis/Virulence factors

Bacillus anthracis contain several

virulence factors:

a- A capsule of D-glutamic acid is anti-

phagocytes and helps the

microorganism to evade the immune

system of the host

Pathogenesis/Virulence factors

b- three exotoxins are product :

1-protactive antigen(PA): bind the

anthrax toxin receptor (ATR) on the

surface of host cells and facilitates the

translocation of the 2 (other

exotoxins, edema factor (EF) and the

lethal factor (LF) into the cell.

2-Edema factor ( EF): is an adenlyate

cyclase that increase intracellular

cAMP Stimuling an efflux of fluids and

ions that results in edema

3-Lethal Factor (LF) is a mitogen –

activated protein kinase kinase

(MAPKK) protease that

Disrupts cell signaling causing cell death

& tissue necrosis.

Mod of action of anthrax Toxin

Laboratory diagnosis

1-smear prepared from exudates, sputum

show gram positive bacilli, non-sporing

bacilli occur in chain

2-cultur: the material is inoculated on

Nutrient Agar & Blood Agar non-

hemolysin, with medosa head shape

appearance ,smear from cultur shows

gram positive bacilli spore in the center

of bacili with chain arrange

Microscopy

Gram stain – for

bacilli demonstration

McFadyean’s reaction

– for capsule

demonstration.

Spore staining – for

spore demonstration.

Gram stain

McFadyaen’s reaction

Spore stain

Culture

Other non-selective media

Nutrient agar –colonies – medusa head

appearance on low power microscopy

Blood agar – usually non-haemolytic

Laboratory diagnosis

3-Macfadyen test: it is special stain for capsular of bacillus anthracis

4-Serological test(Ascoli Test): it is precipitate & rapid diagnosis zone of precipitate at junction of tissue extract & antiserum within 5 minutes at room temperature means positive result of Ascoli Test.

5-Animal inoculation: injected subcutaneously in guinea big which dies within 36-48 hours, smear from heart blood & spleen show gram positive bacilli

Ascoli Test

http://microbewiki.kenyon.edu/index.php/Anthrax

https://sites.google.com/site/allmicrobiologysite/medic

al-microbiology-ii/summary-of-bacterial-

pathogens/bacillus-anthracis

http://www.cdc.gov/anthrax/

http://www.hpa.org.uk/webw/HPAweb&Page&HPAwebAutoListName/Page/1204619483853

References