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Questions and Answers
Which of the following virulence factors of Pseudomonas aeruginosa directly impairs the respiratory tract's defense mechanisms?
Which of the following virulence factors of Pseudomonas aeruginosa directly impairs the respiratory tract's defense mechanisms?
- Pyocyanin, damaging cilia and mucosal cells. (correct)
- Exotoxin A, inhibiting protein synthesis via EF-2 inactivation.
- Elastases and alkaline protease, degrading structural proteins.
- Alginate, contributing to biofilm formation and chronic colonization.
How does Pseudomonas aeruginosa contribute to the pathogenesis of ecthyma gangrenosum observed in bacteremia?
How does Pseudomonas aeruginosa contribute to the pathogenesis of ecthyma gangrenosum observed in bacteremia?
- Through the secretion of endotoxins, inducing a localized Shwartzman reaction in dermal blood vessels. (correct)
- Through the release of exotoxin A, leading to localized tissue necrosis and subsequent vascular damage.
- Through the action of elastases and alkaline protease, directly causing necrotic lesions in cutaneous tissues.
- Through the production of pyoverdin, creating iron-depleted conditions that promote localized tissue invasion.
Why are infections caused by Pseudomonas aeruginosa particularly challenging to treat in clinical settings?
Why are infections caused by Pseudomonas aeruginosa particularly challenging to treat in clinical settings?
- Due to its ability to form endospores, which allows it to survive harsh environmental conditions and resist antibiotic treatment.
- Due to its dependence on a type I secretion system, which facilitates rapid efflux of antibiotics.
- Due to its non-fermentative metabolism and intrinsic resistance mechanisms. (correct)
- Due to its obligate anaerobic respiration, rendering many common antibiotics ineffective.
Which characteristic of Pseudomonas aeruginosa most directly contributes to its ability to persist in hospital environments and cause nosocomial infections?
Which characteristic of Pseudomonas aeruginosa most directly contributes to its ability to persist in hospital environments and cause nosocomial infections?
In the context of Pseudomonas aeruginosa keratitis, what is the most critical factor that determines the rapid progression and severity of the eye infection?
In the context of Pseudomonas aeruginosa keratitis, what is the most critical factor that determines the rapid progression and severity of the eye infection?
How does Exotoxin A contribute to the pathogenesis of Pseudomonas aeruginosa infections?
How does Exotoxin A contribute to the pathogenesis of Pseudomonas aeruginosa infections?
What is the significance of Pseudomonas aeruginosa's ability to produce pyocyanin, pyoverdin, and pyorubin in the context of its pathogenicity?
What is the significance of Pseudomonas aeruginosa's ability to produce pyocyanin, pyoverdin, and pyorubin in the context of its pathogenicity?
Which aspect of Pseudomonas aeruginosa's metabolism is most relevant to its identification in clinical microbiology laboratories?
Which aspect of Pseudomonas aeruginosa's metabolism is most relevant to its identification in clinical microbiology laboratories?
Considering the multiple resistance mechanisms employed by Pseudomonas aeruginosa, what is the most effective strategy for antimicrobial susceptibility testing and treatment planning?
Considering the multiple resistance mechanisms employed by Pseudomonas aeruginosa, what is the most effective strategy for antimicrobial susceptibility testing and treatment planning?
In a patient with cystic fibrosis, which virulence factor of Pseudomonas aeruginosa is most responsible for the chronic lung infections?
In a patient with cystic fibrosis, which virulence factor of Pseudomonas aeruginosa is most responsible for the chronic lung infections?
Flashcards
Pseudomonas aeruginosa Characteristics
Pseudomonas aeruginosa Characteristics
Gram-negative, aerobic rods that produce pigments like pyocyanin (blue) and pyoverdin (yellow-green).
Pseudomonas aeruginosa Virulence Factors
Pseudomonas aeruginosa Virulence Factors
Capsular, enzymes, endotoxins, exotoxins, adhesions, elastases, alkaline protease, pyocyanin, and a type III secretion system
Exotoxin A Mechanism
Exotoxin A Mechanism
ADP-ribosylates elongation factor 2 (EF-2), halting protein synthesis and causing cell/tissue necrosis.
Pyocyanin Function
Pyocyanin Function
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Infections caused by Pseudomonas
Infections caused by Pseudomonas
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Pseudomonas aeruginosa Habitats
Pseudomonas aeruginosa Habitats
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Treatment for Pseudomonas
Treatment for Pseudomonas
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Pseudomonas Keratitis
Pseudomonas Keratitis
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Ecthyma Gangrenosum
Ecthyma Gangrenosum
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Pulmonary Infections
Pulmonary Infections
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Study Notes
- Pseudomonas aeruginosa is a bacterium that causes sepsis, nosocomial pneumonia, and nosocomial UTIs.
- It particularly affects surgical sites, severe burns, patients undergoing chemotherapy, or those on antibiotic therapy.
- This bacterium is Gram-negative, slightly curved, arranged in pairs, and motile.
- It is a strict aerobe.
- Pseudomonas aeruginosa produces diffusible pigments, including pyocyanin (blue), pyoverdin (yellow-green), and pyorubin (reddish-brown).
- It is a non-fermenter, oxidase, catalase, and citrate positive
- Pseudomonas aeruginosa can be found in soil, water, plants, and animals, as well as in moist hospital environments.
- It is opportunistic, meaning it can be found in healthy people without causing disease.
- Virulence factors include: capsule (mucoid colonies), enzymes, endotoxins, exotoxins, adhesions (flagella, pili, LPS, alginate), elastases and alkaline protease, pyocyanin, and type III secretion system.
- Pyocyanin damages the cilia and mucosal cells of the respiratory tract.
- It causes opportunistic infections of existing wounds like burns and localized infections of hair follicles from contaminated water.
- Can cause external otitis, swimmer’s ear, chronic otitis media, and malignant external otitis (severe in diabetes and the elderly).
- Pseudomonas keratitis is an eye infection that can occur after trauma to the cornea, potentially leading to corneal ulcers and rapid disease progression.
- Bacteremia caused by Pseudomonas aeruginosa can lead to ecthyma gangrenosum
- Mortality rate is higher in affected patients and can be caused by neutropenia, diabetes, extensive burns, and hematologic malignancies
- Endocarditis is rare, primarily seen in IV drug users.
- This bacterium is resistant to many antibiotics.
- Treatment options include antipseudomonal penicillin (piperacillin/tazobactam or ticarcillin/clavulanate) plus an aminoglycoside (gentamicin or amikacin).
- Ceftazidime is also effective, and highly resistant strains may respond to colistin (polymyxin E).
- For UTIs, ciprofloxacin can be used.
- Exotoxin A causes ADP-ribose to elongation factor 2 (EF-2), which is needed for protein synthesis.
- This causes tissue necrosis.
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