Gas gangrene :
Gangrene is the anaerobic wound infection in which invasion
of clostridium Perfringens into muscles and tissues resulting myo necrosis with
accumulation of seros anginous exudates and gases occurs.
Pathogenesis:
Sources :
·
Road dust
·
Contaminated soil
·
Contaminated cloth
·
Infected person
·
Bits of clothing
Mode of transmission :
Road accident – Due to road accident organism may be penetrated into
skin through minor trauma.
Crushing of large muscle masses- it enables the
bacilli to be multiplied in injured site.
Surgical operation : improper
handling procedure may lead to infection.
Unhygienic practice : when the person comes in contact with dirty soil,
infection may be resulted.
Endogenous : usually this organism is the normal be developed in
immuno compromised persons.
Gas gangrene pathogenesis :
·
It is otherwise termed as anaerobic myositis.
·
It is sever and lethal infection.
·
It is associated with invasion of organism into
healthy muscles and abundant formation of exotoxin.
·
It may develop if condition is favourable.
·
Organism may be penetrated through cut or
abrasion.
·
Once it is penetrated which utilize the
nutrients from the localized site.
·
The crushing of tissues resulted and
multiplication of organism occurs.
·
However
favourable conditions of low oxygen tension resulted due to interruption
of blood supply and aerobic bacteria that use up more and more oxygen.
·
This intiate to germinate the spore thereby
rapid vegetative growth will be resulted in dead tissues.
·
Exotoxin are relased especially , alpha toxin
plays a major role.
·
Exotoxin degrade tissue and some ground
materials.
·
Hyaluronic acid in tissues is degraded by
hyaluronidase enzyme.
·
Injured necrotic tissues with accumulation of
toxin and gas is the characterstics features of gangrene.
·
Hyaluronidase degrade tissue and release gas due
to fermentation.
·
Gas is fowl smelling results in pulpution .
·
Tissue necrosis gas accumulation combining
together to form as gangerene.
·
Horribly damage and enters in blood affect other
tissue.
Types of gangrene:
1.
Moist gangrene
2.
Dry gangrene.
Moist gangrene :
It develops due to sudden stoppage of blood .
It may be resulted from burning by heat or acid.
Severe freezing and physical accident plays a vital role in
causing this type of gangrene.
It is characterized by the presence of gangrene with swollen
often blistered.
In this gangrene , toxin may be formed and spread in
affected area.
Dry gangrene :
It develops due to reduction of blood flow in arteries no
bacterial decomposition involved it is characterized by the presence of dried
tissues with shriveled.
It is seen mostly in diabetic cases it appears with a
symptom of shrinking of tissues lacking of pulse.
Nagler reaction :
1.
This test is done for detecting the organism which
is capable of producing toxin.
2.
In this test organism from the suspected case is
inoculated into the media containing 6% of agar, 5% of filedes peptic digest of
sheep blood and 20% human serum or 5% egg yolk.
3.
At the bottom of the plate draw a straight line
to make the plates into two half.
4.
One half of the plate is spread with anti toxin
the other half of the plate kept free with anti toxin. Followed by the plate is
incubated at 370c for 24 hours.
5.
Colonies on the area without anti toxin shows
opacity, while the area spread with prior anti toxin shows no opacity due to
neutralization of alpha toxin usually lecithinase is produced by organism which
splits lecithin into phosphorylcholine and lipid. This lipid deposition around
the colony indicates opacity.
Culture :
Take wound swab ---Ã
Transported into laboratory------Ã
inoculate it into selective media ---> sub culture on blood agar incubated
anaerobically at 48 to 72 hours ----> observe the colony morphology.
Clostridium difficle :
Clostridium difficle is a gram positive anaerobic rod shaped
bacteria, it belongs to the family clostridiaceae. It is non capsulated ,
motile organism motility occurs due to the presence of peritrichous flagella.
Moreover it is spore forming spores are usually seen in sub
terminal region and some time it appears as drum stick. It is normal inhabitant
of intestine and is effectively causing a unique colonic disease called
pseudomembranous colitis.
Factors responsible for
infections :
1.
Prolonged hospital stay
2.
Prolonged anti microbial use
3.
Host immune response
4.
Toxin
5.
Age
Route of infection : faeco oral route
Spread – spore spread through hands of health care workers.
Pathophysiology :
This infection is developed due to alteration of normal
flora in intestine. When the antibiotic kills off other competing bacteria
means exogenous flora that initiates the growth of normal flora such as C
difficle. Thus it colonize well in the gut and cause pseudomembranous colitis.
Infections symptoms:
Diarrohea, fever, nausea and the abdominal pain are the
major symptoms.
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