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DOMAIN:
BACTERIA

DIVISION:
FIRMICUTES

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CLASS:
BACILLI

ORDER:
BACILLALES

FAMILY:
BACILLACEAE

GENUS:
bacillus

Taxonomy

This
genus is one of the largest and most ubiquitous, and has gained notoriety with
taxonomists for its extreme phenotypic diversity and heterogeneity.

The
genus Bacillus currently comprises 268 species and 7 subspecies although a few
of these have been assigned to other genera

commonly
found in the environment and as laboratory contaminants but a few of the
species have been known to cause infections in humans

Two
Bacillus species are considered medically significant: B. anthracis, which
causes anthrax, and B. cereus, which causes a foodborne illness similar to that
of Staphylococcus

 

 

 

 

 

 

 

General
characteristics of bacillus species

·        
Large,grame-positive rods

·        
Endospore produced

·        
Aerobes or facultative anaerobes

·        
Growth on non-enriched media

·        
Most species motile, catalase-positive and oxidase-negative

·        
Majority are non-pathogenic environmental organism

 

Biochemical
characteristics

·        
Bacillus are catalse positive

·        
The ability to grow aerobically and to produce catalase
distinguishes Bacillus species from the clostridia,which is also grame
positive,endospore forming rods.

Colonial
characteristics of bacillus species

·        
Bacillus anthracic:colonies are upto 5 mm in dimeter,flat,dry
greyish and with ground glass apperance after 48 hours incubation

·        
Medusa head apperance,weakly haemolytic

·        
In gelatine stab inverted fir tree appearance

·        
B.cerus: Colonial
characteristic is similar to the B.anthracic but colonies are slightly larger
with greenish tinge, majority strains produce wide zone of haemolysis

·        
B.licheniformis:colonies
are dull, rough wrinkled and strong adherent to the agar characteristics hair
like outgrowth produced from streaks of the organism on agar media

Usual
habitat

·        
Bacillus species widely distributed in environment mainly because
they produce highly resistant endospore

·        
In soil endospore of bacillus anthracic can survive for more than
50 years

·        
Some bacillus sp. can tolerate extremely adverse condition such as
desiccation and high temperature

·        
Most species are saprophytes.

 

 

 

 

 

 

 

 

Clinical
infection

·        
Bacillus anthrax is the most important disease of these group

·        
Bacillus licheniformis is an emerging pathogen causes of abortion
in cattle and sheep

·        
B.cerus is important in human food poisoning and its associated
with rare cases of mastitis in cow

Clinical
manifestation of diseases caused by bacillus anthracis and other bacillus
species

Bacillus species

Susceptible animal

Clinical manifestations

B.anthracis:              Cattle
and sheep :                 Fatal per
acute or acut septicaemia                                        

Pigs

:                            Subacut anthrax
with  oedemaotus swelling  in pharyngeal region:an intestinal form
with higher mortality is less common

 

Horse

: Subacut
anthrax with localized oedema; septicaemia with colic and enteritis some time
occurs

 

Humans

Skin,
pulmonary and intestinal forms of anthrax are recorded in man periodically

 

 

 

 

 

Bacillus

•     
1972,Recognizedby Ferdinand cohn and named as Bacillus subtilis

•     
In 1976,Koch provided the proof that a specific micro

          Organisms could cause a specific disease(bacillus
antrax)

CLASSIFICATION

 

 

 

 

 

 

 

 

Differentiating
features of bacillus anthracis and B.cereus

                                        Features

B.antracis

B.ceresus

q  Motility

Non-motile

motile

q  Appearance
on sheep blood agar

Non-haemolytic

haemolytic

q  Susceptibility
to penicillin(10unit disc)

Susceptible

Resistant

q  Lecithinase
activity on eggs

Weak
and slow

Strong
and rapid

q  Effect of
gamma phase

Lysis

Lysis
rare

q  Pathogenicity
for animal

Death
in 24 to 48h

NO
effect

 

MAJAR
ZOONOTIC DISEASE FROM BACILLUS SPECIES:ANTHRAX

Anthrax

·        
Splenic Fever

·        
Wool Sorter’s Disease

·        
Milzbrand

·        
Tarka

·        
Charbon

·        
Malignant Carbuncle

·        
It is a acute infectious disease of livestock

·        
It is per-acute septicaemic disease of livestock causing death

·        
Gram + ve

·        
Straight 

·        
Very large rod shaped

·        
Non- motile

·        
Capsulated

·        
Aerobic 

·        
Spore bearing

·        
Remain in chain

 

 

Transmission

·        
Spores- soil-  Soil born
infection occur

·        
( alkaline soil –predisposes)

·        
Streams, rivers & flood – carry spores to new places

·        
Carnivores- eat infected carcass

·        
Flying Birds- infection spread Cattle infect while grazing-
infected pasture

·        
Bacteria enters through oral mucosa

·        
New area infected by

·        
Contaminated  animal
products like bone meal, fertilizer, hide, hair, wool, grain or forage

Epidemiology

·        
Ancient disease

·        
Worldwide in distribution

·        
In India Disease is enzootic

·        
Occur in almost all district of different states

Pathogenesis

·        
Toxin

·        
Oedema of tissues

·        
death(shock & acute renal failure)

·      
Death- damage CNS- anoxia

Clinical
Findings

·        
Different in Different species ( I P- 2-10 days)

·        
Cattle & Buffalo

Acute Form

·        
Temp 104 to 108?F

·        
Anorexia

·        
Bloat

·        
Depression

·        
Pulse & respiration increased

·        
Muscular tremors

·        
Dyspnoea-mouth breathing – oxygen hunger

·        
Death in 48 hrs

·        
In per-acute form animal found dead without showing signs

·        
Subacute Form  Characterized
by oedema

·        
Oedema is noticed under the neck, brisket region, thorax, abdomen
and flank

·        
Due to oedema of thorax & brisket region —      respiratory distress

·        
Terminal stages- jugular pulse is noticed

·        
Pregnant animals-abort

Diagnosis

·        
Animal that die suddenly with bloody discharges from mouth,
nostrils & anus must be suspected for anthrax 

·        
Should not open the carcass

·        
Blood smear examination

·        
Thick blood smear stained with polychrome        methylene blue or Giemsa’s stain  

·        
Polychrome methylene blue- blue rods in short chain with pink
capsules- McFadyean’s reaction

·        
Giemsa’s stain- reddish discolouration of capsule 

 

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