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PSEUDOMONASPSEUDOMONAS
Pseudomonas Pseudomonas aeruginosaaeruginosa
Also known as burkholderia aeruginosa.Also known as burkholderia aeruginosa.
Other species of pseudomonas areOther species of pseudomonas are
1. Pseudomonas cepacia1. Pseudomonas cepacia
2. Pseudomonas maltophilia2. Pseudomonas maltophilia
3. Pseudomonas pseudomallei3. Pseudomonas pseudomallei
PropertiesProperties::
1. Pseudomonas is a gram negative 1. Pseudomonas is a gram negative rodrod
with polar flagellawith polar flagella
2. It is strict or obligate aerobe unlike 2. It is strict or obligate aerobe unlike
thethe
members of enterobacteriacea.members of enterobacteriacea.
Therefore it gets its energy throughTherefore it gets its energy through
aerobic processes and not throughaerobic processes and not through
fermentation.fermentation.
3. It is lactose non fermenter3. It is lactose non fermenter
Gram-stained Pseudomonas Gram-stained Pseudomonas aeruginosa bacteria (pink-red aeruginosa bacteria (pink-red
rods).rods).
4. Oxidase positive because contains4. Oxidase positive because contains high high
levels of cytochrome oxidase. levels of cytochrome oxidase.
5. 5. It can grow even in tap water with little It can grow even in tap water with little
amount of nutrients.amount of nutrients.
6. 6. It can survive and multiply over a wide
temperature range (20 to 42C) in
almost any environment, including one
with a high salt content.
P. aeruginosa and cepacia have strong ability to P. aeruginosa and cepacia have strong ability to
withstand the disinfectants. This property also withstand the disinfectants. This property also
makes them commonest nosocomial organism.makes them commonest nosocomial organism.
8. Pseudomonas produces two pigments.8. Pseudomonas produces two pigments.
a. Pyocanin. It gives a blue colour to the pus in a. Pyocanin. It gives a blue colour to the pus in
wounds.wounds.
b. Pyoverdin.( Flourescein). A yellow green b. Pyoverdin.( Flourescein). A yellow green
pigment pigment
which flouresces under ultraviolet light.which flouresces under ultraviolet light.
In lab these pigments impart agar a blue In lab these pigments impart agar a blue
green colourgreen colour
P. aerugenosa synthesizes both pigments P. aerugenosa synthesizes both pigments
while others produce only pyoverdin.while others produce only pyoverdin.
EpidemiologyEpidemiology::
The primary habitat of P. aeruginosa is the
environment, chiefly found in soil and chiefly found in soil and
water. water.
Also found in 10% people as normal flora of Also found in 10% people as normal flora of
colon.colon.
Infections have resulted from the
growth of Pseudomonas in medications,
contact lens solutions, and even in some
disinfectants.
It is responsible for 10-20% nosocomial It is responsible for 10-20% nosocomial
infections.infections.
Commonest cause of hospital acquired Commonest cause of hospital acquired
gram negative pneumonia.gram negative pneumonia.
PathogenesisPathogenesis:: It mainly causes It mainly causes
1.1. Pneumonia.Pneumonia.
2.2. UTI.UTI.
3.3. Sepsis in immunocompromized patientsSepsis in immunocompromized patients
4.4. Infections in burnt tissues.Infections in burnt tissues.
Pathogenecity is based on multiple virulence Pathogenecity is based on multiple virulence
factors.factors.
1. Endotoxins. Produce sepsis and septic shock.1. Endotoxins. Produce sepsis and septic shock.
2. Exotoxins. Two main exotoxins.2. Exotoxins. Two main exotoxins.
a. Exotoxin Aa. Exotoxin A
b. Exotoxin S or Exoenzyme Sb. Exotoxin S or Exoenzyme S
Exotoxin A is the best known. It produces tissueExotoxin A is the best known. It produces tissue
necrosis. Impairs protein synthesis of the cells.necrosis. Impairs protein synthesis of the cells.
Exoenzyme S is produced by bacteria mainly in Exoenzyme S is produced by bacteria mainly in
burntburnt
tissues. It acts by damaging cytoskeleton.tissues. It acts by damaging cytoskeleton.
P. aeruginosa strains that posses type III P. aeruginosa strains that posses type III
secretion system are more virulent.secretion system are more virulent.
Type III secretion systems work Type III secretion systems work through pumps in the bacterial walls. through pumps in the bacterial walls. ExoS is transported through this system.ExoS is transported through this system.
3. 3. EnzymesEnzymes:: Two enzymes Two enzymes
a.a. Elastase.Elastase.
b.b. Alkaline Protease are important. Alkaline Protease are important.
They are toxic to tissues and facilitate the They are toxic to tissues and facilitate the
invasion of organism into the blood stream. invasion of organism into the blood stream.
Others include lecithinase and Others include lecithinase and
phospholipases.phospholipases.
They appear to act together to break They appear to act together to break
down lipids and lecithindown lipids and lecithin. .
Clinical findingsClinical findings: : It can cause It can cause infection any where in body but infection any where in body but commonly it causescommonly it causes
1. UTI1. UTI
2. Pneumonia2. Pneumonia
3. Infection in burn wounds. 3. Infection in burn wounds.
When disseminates it causes. When disseminates it causes.
4. Sepsis4. Sepsis
5. Necrotic skin lesions called eccthyma5. Necrotic skin lesions called eccthyma
gangrenosum.gangrenosum.
6. Also causes endocarditis in patients on 6. Also causes endocarditis in patients on
I.V drugs use.I.V drugs use.
7. Severe external otitis ( malignant otittis 7. Severe external otitis ( malignant otittis
externa) and folliculitis in persons using externa) and folliculitis in persons using
bath tubs and swimming pools.bath tubs and swimming pools.
8. Sever osteochondritis of foot8. Sever osteochondritis of foot
9. Corneal infections in contact lens users9. Corneal infections in contact lens users
Lab diagnosisLab diagnosis::1. 1. Gram staining.Gram staining.
2. Inoculation of nutrient agar2. Inoculation of nutrient agar
3. Inoculation of selective medium like 3. Inoculation of selective medium like Macconkey’s agar or EBMMacconkey’s agar or EBM
4. Alkaline reaction on TSI agar4. Alkaline reaction on TSI agar
5. Oxidase test is positive5. Oxidase test is positive
6. Fruity or grape like aroma6. Fruity or grape like aroma
P. aeruginosa isolates may produce three P. aeruginosa isolates may produce three
types of colony. types of colony.
1. Natural isolates from soil or water 1. Natural isolates from soil or water
produce a small, rough colony. produce a small, rough colony.
2. Clinical samples produce a colony with 2. Clinical samples produce a colony with
fried-egg appearance.fried-egg appearance.
Pseudomonas aeruginosa colonies Pseudomonas aeruginosa colonies on agaron agar
The soluble blue pigment pyocyanin is The soluble blue pigment pyocyanin is produced by many, but not all, strains produced by many, but not all, strains
of Pseudomonasof Pseudomonas
TreatmentTreatment:: Resistant organism so treatment should Resistant organism so treatment should
be done according to C/Sbe done according to C/S However drugs of choice are Ticarcillin However drugs of choice are Ticarcillin
or Piperacillin in combination with or Piperacillin in combination with gentamicin or Amikacingentamicin or Amikacin