Lecture 13 BIOL 533 1
Pseudomonaceae
BIOL 533
Lecture 13
Medical Microbiology
Lecture 13 BIOL 533 2
General Aspects
? Ecology
– Found throughout the environment
? Very simple nutritional requirements
– Not usually in normal flora unless hospitalized
or immunocompromised
Lecture 13 BIOL 533 3
General Aspects
? Virulence
– Possess number of structural factors and
toxins
– Resistant to most common antibiotics
– Surprising that they do not constitute problem
in general population
Lecture 13 BIOL 533 4
Microbial Physiology
and Structure
? Morphology
– Straight or slightly curved Gram— bacterial
? Polar flagella; motile
– Some strains appear mucoid due to
polysaccharide capsule
– Some produce diffusible pigments
? Pyocyanin (blue),fluorescin (yellow),pyorubin
(red-brown)
Lecture 13 BIOL 533 5
Microbial Physiology
and Structure
? Physiology
– Carbohydrate fermentation
? Use only few CHO using oxidative pathways
– Glucose,ribose,gluconate
? Oxygen is terminal electron acceptor
? Presence of cytochrome oxidase
– Distinguishes from Enterobacteriaceae
– Anarobic growth can occur by using mitrate
as terminal acceptor
Lecture 13 BIOL 533 6
Virulence Factors
? Adhesins,pili and nonpilus adhesins
– Production of neuraminidase enhances
adherence
? Alginate (mucoid layer),Protects against
phagocytosis and facilitates adherence to
host cells
Lecture 13 BIOL 533 7
Virulence Factors
? Elastase,cause damage to blood vessel
walls,resulting in hemorrhagic lesions
(ecthyma gangrenosum)
– Associated with disseminated Pseudomonas
infections
? Pyocyanin,mediates tissue damage
through toxic oxygen radicals
Lecture 13 BIOL 533 8
Toxins
? Exotoxin A,mechaism like diphtheria
toxin,but much milder
– Two toxins are structurally and
immunologically different
? Exoenzyme S,also ADP-ribosyltrnasferase,
but heat stabile
– Found in 33.3% clinical isolates
Lecture 13 BIOL 533 9
Clinical Syndromes of
Pseudomonas aeruginosa
? Bacteremia
– Common in patients with neutropenia,
diabetes mellitus,extensive burns,a
hematologic malignancies
– Originate from infections of lower respiratory
tract,urinary tract,skin,and soft tissue
– Associated symptoms,minority of patients
have ecthyma gangrenosum
Lecture 13 BIOL 533 10
Clinical Syndromes of
Pseudomonas aeruginosa
? Endocarditis
– Observed primarily in drug abusers
– Source is contaminated drug equipment
– Anatomy of heart affected
? Tricuspid valve,chronic and more favorable
prognosis
? Aortic or mitral valve,acute and frequently fatal
Lecture 13 BIOL 533 11
Clinical Syndromes of
Pseudomonas aeruginosa
? Pulmonary infections
– Range from colonization to severe necrotizing
bronchopneumonia
– Colonization seen in patients with cystic
fibrosis,other chronic lung diseases,and
neutropenia
Lecture 13 BIOL 533 12
Clinical Syndromes of
Pseudomonas aeruginosa
? Ear infections
– Swimmer’s ear,can be managed with topical
antibiotics and drying agents
– Malignant external otitis,more virulent; can
invade underlying tissues and cause death
? Surgical and antimicrobial intervention required
Lecture 13 BIOL 533 13
Clinical Syndromes of
Pseudomonas aeruginosa
? Burn infections—severe burns
– Colonization of wound followed by local
vascular damage and tissue necrosis
? Leading to bacteremia
– Predisposition
? Moist tissue surface and absence of neutrophils
– Topical creams and wound management has
had only limited success
Lecture 13 BIOL 533 14
Clinical Syndromes of
Pseudomonas aeruginosa
? Other infections
– Localized in gastrointestinal and urinary tracts
– Eye and central nervous system
– Musculoskeletal system
Lecture 13 BIOL 533 15
Clinical Syndromes of
Pseudomonas aeruginosa
? Prerequisites for infection
– Presence of organism in moist reservoir
– Circumvention or absence of host defenses
? Cutaneous trauma
? Elimination of normal flora
? Neutropenia
Lecture 13 BIOL 533 16
Laboratory Diagnosis
? Grow on most common laboratory media
? Identification
– Morphology
? Colony size and hemolysis,flat colony with
spreading border
? Pigmentation,green
? Odor,sweet,grape-like
– Oxidase+
Lecture 13 BIOL 533 17
Treatment
? Resistant to large number of antibiotics
? Problems,
– Production of ?-lactamase
– Aminoglycosides ineffective in acidic
environment of abscess
? Successful treatment
– Combination of ?-lactum antibiotic and
amioglycoside
Lecture 13 BIOL 533 18
Prevention
? Possibly impossible in hospital
environment
? Prevent inappropriate use of broad-
spectrum antibiotics
Lecture 13 BIOL 533 19
Lecture 13
? Questions?
? Comments?
? Assignments..,
Pseudomonaceae
BIOL 533
Lecture 13
Medical Microbiology
Lecture 13 BIOL 533 2
General Aspects
? Ecology
– Found throughout the environment
? Very simple nutritional requirements
– Not usually in normal flora unless hospitalized
or immunocompromised
Lecture 13 BIOL 533 3
General Aspects
? Virulence
– Possess number of structural factors and
toxins
– Resistant to most common antibiotics
– Surprising that they do not constitute problem
in general population
Lecture 13 BIOL 533 4
Microbial Physiology
and Structure
? Morphology
– Straight or slightly curved Gram— bacterial
? Polar flagella; motile
– Some strains appear mucoid due to
polysaccharide capsule
– Some produce diffusible pigments
? Pyocyanin (blue),fluorescin (yellow),pyorubin
(red-brown)
Lecture 13 BIOL 533 5
Microbial Physiology
and Structure
? Physiology
– Carbohydrate fermentation
? Use only few CHO using oxidative pathways
– Glucose,ribose,gluconate
? Oxygen is terminal electron acceptor
? Presence of cytochrome oxidase
– Distinguishes from Enterobacteriaceae
– Anarobic growth can occur by using mitrate
as terminal acceptor
Lecture 13 BIOL 533 6
Virulence Factors
? Adhesins,pili and nonpilus adhesins
– Production of neuraminidase enhances
adherence
? Alginate (mucoid layer),Protects against
phagocytosis and facilitates adherence to
host cells
Lecture 13 BIOL 533 7
Virulence Factors
? Elastase,cause damage to blood vessel
walls,resulting in hemorrhagic lesions
(ecthyma gangrenosum)
– Associated with disseminated Pseudomonas
infections
? Pyocyanin,mediates tissue damage
through toxic oxygen radicals
Lecture 13 BIOL 533 8
Toxins
? Exotoxin A,mechaism like diphtheria
toxin,but much milder
– Two toxins are structurally and
immunologically different
? Exoenzyme S,also ADP-ribosyltrnasferase,
but heat stabile
– Found in 33.3% clinical isolates
Lecture 13 BIOL 533 9
Clinical Syndromes of
Pseudomonas aeruginosa
? Bacteremia
– Common in patients with neutropenia,
diabetes mellitus,extensive burns,a
hematologic malignancies
– Originate from infections of lower respiratory
tract,urinary tract,skin,and soft tissue
– Associated symptoms,minority of patients
have ecthyma gangrenosum
Lecture 13 BIOL 533 10
Clinical Syndromes of
Pseudomonas aeruginosa
? Endocarditis
– Observed primarily in drug abusers
– Source is contaminated drug equipment
– Anatomy of heart affected
? Tricuspid valve,chronic and more favorable
prognosis
? Aortic or mitral valve,acute and frequently fatal
Lecture 13 BIOL 533 11
Clinical Syndromes of
Pseudomonas aeruginosa
? Pulmonary infections
– Range from colonization to severe necrotizing
bronchopneumonia
– Colonization seen in patients with cystic
fibrosis,other chronic lung diseases,and
neutropenia
Lecture 13 BIOL 533 12
Clinical Syndromes of
Pseudomonas aeruginosa
? Ear infections
– Swimmer’s ear,can be managed with topical
antibiotics and drying agents
– Malignant external otitis,more virulent; can
invade underlying tissues and cause death
? Surgical and antimicrobial intervention required
Lecture 13 BIOL 533 13
Clinical Syndromes of
Pseudomonas aeruginosa
? Burn infections—severe burns
– Colonization of wound followed by local
vascular damage and tissue necrosis
? Leading to bacteremia
– Predisposition
? Moist tissue surface and absence of neutrophils
– Topical creams and wound management has
had only limited success
Lecture 13 BIOL 533 14
Clinical Syndromes of
Pseudomonas aeruginosa
? Other infections
– Localized in gastrointestinal and urinary tracts
– Eye and central nervous system
– Musculoskeletal system
Lecture 13 BIOL 533 15
Clinical Syndromes of
Pseudomonas aeruginosa
? Prerequisites for infection
– Presence of organism in moist reservoir
– Circumvention or absence of host defenses
? Cutaneous trauma
? Elimination of normal flora
? Neutropenia
Lecture 13 BIOL 533 16
Laboratory Diagnosis
? Grow on most common laboratory media
? Identification
– Morphology
? Colony size and hemolysis,flat colony with
spreading border
? Pigmentation,green
? Odor,sweet,grape-like
– Oxidase+
Lecture 13 BIOL 533 17
Treatment
? Resistant to large number of antibiotics
? Problems,
– Production of ?-lactamase
– Aminoglycosides ineffective in acidic
environment of abscess
? Successful treatment
– Combination of ?-lactum antibiotic and
amioglycoside
Lecture 13 BIOL 533 18
Prevention
? Possibly impossible in hospital
environment
? Prevent inappropriate use of broad-
spectrum antibiotics
Lecture 13 BIOL 533 19
Lecture 13
? Questions?
? Comments?
? Assignments..,
