Podcast
Questions and Answers
Which virulence factor of Pseudomonas aeruginosa directly impairs the function of respiratory cilia and mucosal cells?
Which virulence factor of Pseudomonas aeruginosa directly impairs the function of respiratory cilia and mucosal cells?
- Alginate
- Elastase
- Pyocyanin (correct)
- Exotoxin A
What is the primary mechanism of action of Exotoxin A in Pseudomonas aeruginosa infections?
What is the primary mechanism of action of Exotoxin A in Pseudomonas aeruginosa infections?
- Blocking nerve signal transmission
- ADP-ribosylation of elongation factor 2 (EF-2) (correct)
- Inhibiting cell membrane synthesis
- Disrupting the Krebs cycle
A patient with cystic fibrosis is diagnosed with a Pseudomonas aeruginosa lung infection. Which characteristic of Pseudomonas aeruginosa is most responsible for the chronicity and severity observed in CF patients?
A patient with cystic fibrosis is diagnosed with a Pseudomonas aeruginosa lung infection. Which characteristic of Pseudomonas aeruginosa is most responsible for the chronicity and severity observed in CF patients?
- Production of pyoverdin
- Type III secretion system
- Exotoxin A secretion
- Alginate production leading to mucoid colonies (correct)
A patient presents with a rapidly progressing corneal ulcer after scratching their eye and swimming in a lake. What virulence factor is most associated with this presentation of Pseudomonas aeruginosa keratitis?
A patient presents with a rapidly progressing corneal ulcer after scratching their eye and swimming in a lake. What virulence factor is most associated with this presentation of Pseudomonas aeruginosa keratitis?
Pseudomonas aeruginosa is inherently resistant to many antibiotics. What is the MOST common mechanism of resistance?
Pseudomonas aeruginosa is inherently resistant to many antibiotics. What is the MOST common mechanism of resistance?
Ecthyma gangrenosum, a skin lesion associated with Pseudomonas aeruginosa bacteremia, is MOST often observed in patients who are:
Ecthyma gangrenosum, a skin lesion associated with Pseudomonas aeruginosa bacteremia, is MOST often observed in patients who are:
Which of the following characteristics differentiates Pseudomonas aeruginosa from most other Gram-negative bacteria?
Which of the following characteristics differentiates Pseudomonas aeruginosa from most other Gram-negative bacteria?
Why is Pseudomonas aeruginosa considered an opportunistic pathogen?
Why is Pseudomonas aeruginosa considered an opportunistic pathogen?
A 70-year-old diabetic patient develops a severe outer ear infection that extends into the skull base. This presentation is MOST consistent with:
A 70-year-old diabetic patient develops a severe outer ear infection that extends into the skull base. This presentation is MOST consistent with:
Which of the following is the MOST appropriate initial empirical antibiotic regimen for a severe Pseudomonas aeruginosa infection, such as ventilator-associated pneumonia, in a region with known high rates of resistance?
Which of the following is the MOST appropriate initial empirical antibiotic regimen for a severe Pseudomonas aeruginosa infection, such as ventilator-associated pneumonia, in a region with known high rates of resistance?
Flashcards
Pseudomonas aeruginosa Morphology
Pseudomonas aeruginosa Morphology
Gram-negative, slightly curved rods, arranged in pairs and motile. Strict aerobes that produce diffusible pigments like pyocyanin (blue), pyoverdin (yellow-green), and pyorubin (reddish-brown).
P. aeruginosa Virulence Factors
P. aeruginosa Virulence Factors
Capsular layer (mucoid colonies), enzymes (elastases, alkaline protease), endotoxins, exotoxins (Exotoxin A), adhesions (flagella, pili, LPS, alginate), and a Type III secretion system.
P. aeruginosa Clinical Infections
P. aeruginosa Clinical Infections
Lower respiratory tract infections (pneumonia), wound infections (burns), urinary tract infections (catheters), external otitis (swimmer’s ear), keratitis (eye infection after trauma), bacteremia (especially in neutropenic patients).
P. aeruginosa Exotoxin A
P. aeruginosa Exotoxin A
Signup and view all the flashcards
Pyocyanin Function
Pyocyanin Function
Signup and view all the flashcards
P. aeruginosa Treatment
P. aeruginosa Treatment
Signup and view all the flashcards
P. aeruginosa: Lower respiratory tract infections
P. aeruginosa: Lower respiratory tract infections
Signup and view all the flashcards
P. aeruginosa Identification
P. aeruginosa Identification
Signup and view all the flashcards
P. aeruginosa: Urinary tract infections
P. aeruginosa: Urinary tract infections
Signup and view all the flashcards
P. aeruginosa: Eye Infections
P. aeruginosa: Eye Infections
Signup and view all the flashcards
Study Notes
- Pseudomonas aeruginosa causes sepsis, nosocomial pneumonia, and nosocomial UTIs, as well as infections of surgical sites, severe burns, and in patients undergoing chemo or antibiotic therapy.
Morphology
- Gram-negative, slightly curved rods arranged in pairs and motile.
- Strict aerobes.
- Produces diffusible pigments: pyocyanin (blue), pyoverdin (yellow-green), pyorubin (reddish-brown).
- Non-fermenter, oxidase, catalase, and citrate positive.
- On nutrient agar, colonies show a blue-green pigment and fruity aroma.
Epidemiology
- Found in soil, water, plants, and animals, as well as moist reservoirs in hospitals.
- Can colonize healthy humans without causing disease, but is an opportunistic pathogen.
- Common cause of nosocomial infections.
Virulence Factors
- Capsule (mucoid colonies).
- Enzymes, endotoxins, exotoxins.
- Adhesions (flagella, pili, LPS, alginate).
- Elastases and alkaline protease.
- Pyocyanin.
- Type III secretion system.
- Alginate is a mucoid exopolysaccharide that forms a capsule.
- Pyocyanin damages the cilia and mucosal cells of the respiratory tract.
Clinical Diseases
- Pulmonary infections can range from asymptomatic colonization to necrotizing bronchopneumonia, especially in cystic fibrosis patients.
- Causes opportunistic infections of existing wounds like burns and localized infections of hair follicles associated with contaminated water (hot tubs).
- External otitis (swimmer’s ear), chronic otitis media, and malignant external otitis (virulent form in diabetes and elderly).
- Pseudomonas keratitis (eye infection) occurs after trauma to the cornea. Corneal ulcers can progress to rapidly eye-threatening disease.
- Bacteremia can cause ecthyma gangrenosum. Mortality rate is higher in affected patients, especially with neutropenia, diabetes, extensive burns, and hematologic malignancies.
- Endocarditis is rare, primarily seen in IV drug users.
Exotoxin A
- Exotoxin A causes ADP-ribose to elongation factor 2 (EF-2), which is necessary for protein synthesis and causes tissue necrosis.
Laboratory Diagnosis
- Clinical samples depend on the disease.
- Gram-negative, rod-shaped bacteria are seen on microscopy.
- On agar, non-lactose fermenting colonies can be seen.
- Blue-green pigment and fruity aroma is seen on nutrient agar.
- It is a non-glucose fermenter and oxidase positive.
Treatment
- Resistant to many antibiotics.
- Antipseudomonal penicillin (piperacillin/tazobactam or ticarcillin/clavulanate) plus an aminoglycoside (gentamicin or amikacin) can be used
- Ceftazidime is also effective.
- Highly resistant strains respond to colistin (polymyxin E).
- For UTI: ciprofloxacin.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
