L27 Pseudomonas and Other Gram Negative Rods Flashcards
What are the key characteristics of glucose non-fermenting gram-negative bacilli?
- Gram-negative
- Non-spore-forming
- Rods or coccobacilli
- Obligate aerobes
- Good growth seen in 24 hours
- Glucose not fermented
What is the natural habitat of glucose non-fermenting gram-negative bacilli?
Water, soil, plants, moist areas, hospital environment
Pseudomonas aeruginosa is an aerobic Gram ___ ___ (shape).
Negative; rod
What are the major virulence factors of P. aeruginosa?
- Motility with polar flagella
- Mucoid polysaccharide slime layer
- Pili on the cell surface
- LPS
- Pyocyanin
- Exotoxin A
- Exoenzyme S
- Elastase
What factors pre-dispose patients to serious infection with P. aeruginosa?
- Burn patients
- CF patients
- Patients with hematologic malignancies
- Immunocompromised patients
True or false - P. aeruginosa can be part of the microbial flora in hospitalized patients and ambulatory, immunocompromised hosts.
True
What skin infections are caused by pseudomonas?
- Burn wounds
- Folliculitis
- Nail infections
What pulmonary infections are caused by/associated with pseudomonas?
- Asymptomatic colonization
- CF and chronic lung disease
- Severe necrotizing bronchopneumonia
- Ventilator associated pneumonia (VAP)
What is the most common cause of VAP?
Pseudomonas
What other infections are caused by Pseudomonas?
UTI, ear infections (swimmer’s ear, malignant external otitis, chronic otitis media), eye infections, bacteremia with ecthyma gangrenosum, endocarditis, osteomyelitis
What is ecthyma gangrenosum?
A well-recognized but uncommon cutaneous infection most often associated with a P. aeruginosa bacteremia; usually occurs in patients who are critically ill and immunocompromised. It is almost always a sign of pseudomonal sepsis. q
What are the symptoms of bacteremia with ecthyma gangrenosum?
Characteristic hemorrhagic pustules or infarcted-appearing areas with surrounding erythema that evolve quickly into necrotic ulcers surrounded by erythema
What are the structural virulence factors of P. aeruginosa?
- Capsule
- Pili
- LPS
- Pyocyanin
How does exotoxin A function?
Exotoxin A blocks protein synthesis and contributes to dermatonecrosis in wounds and tissue damage in lungs
How does exoenzyme S function?
Exoenzyme S is an ADP-ribosylating toxin that causes epithelial damage, which facilitates bacterial spread, tissue invasion, and necrosis
How does elastase (Las A and Las B) function?
Causes tissue destruction and hemorrhagic lesions by degrading elastin and complement components, and inhibiting neutrophil chemotaxis and function
Describe growth of P. aeruginosa.
Grows on blood and MacConkey agar, producing spreading colonies with a metallic sheen. It is temperature tolerant and grows at 42 degrees Celcius.
What are some ID aspects of P. aeruginosa?
- Glucose non-fermenter
- Oxidase positive
- Grape-like odor
- Produces pyocyanin
How are Pseudomonas infections treated?
They are resistant to many common antibiotics used for Gram negative infections due to changes in porins. Combination therapy of cell wall active agent + aminoglycosides are needed for serious systemic infection.
What is the habitat of Burkholderia pseudomallei?
Soil, water, and vegetation of Southeast Asia
What disease does Burkholderia pseudomallei cause?
Melioidosis
B. pseudomallei is a category B ___.
Biothreat agent