Microbiology: Pseudomonas & Stenotrophomonas
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Questions and Answers

Which characteristic does Pseudomonas aeruginosa NOT have?

  • Oxidase positive
  • Sweet grape-like odor
  • Obligate aerobe
  • Fermets lactose (correct)
  • What is the main drug of choice for treating Stenotrophomonas maltophilia infections?

  • Bactrim (correct)
  • Vancomycin
  • Levofloxacin
  • Ciprofloxacin
  • Which of the following infections is most commonly associated with Pseudomonas aeruginosa?

  • Glanders from zoonotic sources
  • Urinary tract infections from E. coli
  • Ventilator-associated pneumonia (correct)
  • Cellulitis from animal bites
  • Which of the following bacteria is known to cause glanders?

    <p>Burkholderia</p> Signup and view all the answers

    What is a significant virulence factor of Pseudomonas aeruginosa?

    <p>Lipopolysaccharide</p> Signup and view all the answers

    Which bacterium is identified as a significant nosocomial pathogen and is highly resistant to treatment?

    <p>Acinetobacter</p> Signup and view all the answers

    How can Pasturella multocida infections typically occur?

    <p>Animal bites</p> Signup and view all the answers

    Which characteristic is true of Moraxella species?

    <p>They are non-motile cocci.</p> Signup and view all the answers

    Which of the following infections is least likely to be caused by Pseudomonas aeruginosa?

    <p>Glanders</p> Signup and view all the answers

    What characteristic is true for Stenotrophomonas maltophilia?

    <p>Oxidizes glucose and maltose</p> Signup and view all the answers

    Which bacterium is primarily an animal pathogen but can also cause cellulitis in humans?

    <p>Pasturella multocida</p> Signup and view all the answers

    Which of the following statements about Acinetobacter is correct?

    <p>It is a significant cause of nosocomial infections.</p> Signup and view all the answers

    What is a common characteristic of the HACEK group of bacteria?

    <p>They normally reside in the oral cavity.</p> Signup and view all the answers

    Which mechanism of resistance is NOT associated with Pseudomonas aeruginosa?

    <p>Beta oxidation</p> Signup and view all the answers

    Which characteristic is unique to Neisseria species compared to other listed bacteria?

    <p>Gram-negative cocci</p> Signup and view all the answers

    What feature is common to the infections caused by Yersinia species?

    <p>Transmitted by wild rodents</p> Signup and view all the answers

    What is a common source of Pseudomonas aeruginosa infections in healthcare settings?

    <p>Moist areas of hospitals</p> Signup and view all the answers

    Which statement correctly describes Stenotrophomonas maltophilia?

    <p>It is oxidase negative.</p> Signup and view all the answers

    What is the preferred drug for treating Stenotrophomonas maltophilia infections?

    <p>Bactrim</p> Signup and view all the answers

    Which characteristic is true for Acinetobacter?

    <p>It is frequently associated with soil and water.</p> Signup and view all the answers

    Which of the following factors contributes to the virulence of Pseudomonas aeruginosa?

    <p>Biofilm formation</p> Signup and view all the answers

    How can humans become infected with Yersinia species?

    <p>By direct contact with wild rodents</p> Signup and view all the answers

    Which bacterium is primarily responsible for causing pneumonia in patients who are mechanically ventilated?

    <p>Pseudomonas aeruginosa</p> Signup and view all the answers

    What characteristic is distinctive of Moraxella species?

    <p>It has a coccobacillus shape.</p> Signup and view all the answers

    Study Notes

    Pseudomonas aeruginosa

    • Main pathogen in humans, commonly found in moist hospital areas
    • Obligate aerobe with a sweet grape-like odor, oxidase-positive
    • Does not ferment glucose or lactose, grows at 42°C
    • Motile, found in water, plants, and animals
    • Causes skin, eye, and ear infections
    • Significant pathogen, responsible for ventilator-associated pneumonia (VAP), nosocomial pneumonia, and urinary tract infections (UTIs)
    • High-risk populations include neutropenic patients, burn patients, those with cystic fibrosis, and those on mechanical ventilation
    • Virulent factors include exotoxin A, pili, lipopolysaccharide, and chronic colonization
    • Resistance mechanisms include beta-lactamase production, biofilm formation, and multidrug efflux pumps

    Stenotrophomas Maltophilia

    • Lavender green or gray color, oxidase-negative
    • Oxidizes glucose and maltose, does not ferment lactose
    • Hospital-acquired infection, treated with Bactrim

    Burkholderia

    • Causes glanders, a zoonotic disease transmissible to humans

    Acinetobacter

    • Aerobic, non-glucose, and non-lactose fermenter, short rods on Gram stain
    • Widely distributed in soil and water, a significant nosocomial pathogen
    • Causes pneumonias, bacteremias, and wound infections
    • Highly resistant, often requiring treatment with colistin

    The HACEK Bacteria

    • Includes Eikenella corrodens, a small, fastidious Gram-negative rod
    • Part of the gingival and bowel flora, oxidase-positive

    Moraxella species

    • Coccobacillus, associated with bronchitis and pneumonia

    Pasturella multocida

    • Primarily an animal pathogen, but can be zoonotic
    • Causes cellulitis via animal bites, non-motile Gram-negative coccobacilli
    • Suspect in skin infections due to cats and dogs, treated with Augmentin

    Yersinia species

    • Infections from wild rodents transmitted to humans and other mammals
    • Responsible for the Black Death, can be used as a biological weapon

    Pseudomonas aeruginosa

    • A common human pathogen
    • Often found in moist hospital environments
    • Requires oxygen for growth (obligate aerobe)
    • Produces a sweet, grape-like odor
    • Positive for oxidase enzyme
    • Does not ferment glucose or lactose
    • Can grow at 42 degrees Celsius

    Infections Associated with Pseudomonas aeruginosa

    • Skin infections
    • Eye infections
    • Ear infections
    • Ventilator-associated pneumonia (VAP)
    • Nosocomial pneumonia
    • Urinary tract infections (UTIs)

    At-Risk Individuals for Pseudomonas aeruginosa Infections

    • Patients with low white blood cell counts (neutropenic)
    • Burn patients
    • Individuals with cystic fibrosis (CF)
    • Patients on mechanical ventilators

    Virulence Factors of Pseudomonas aeruginosa

    • Exotoxin A
    • Pili
    • Lipopolysaccharide
    • Ability to colonize persistently

    Resistance Mechanisms of Pseudomonas aeruginosa

    • Production of beta-lactamase (enzyme that breaks down antibiotics)
    • Ability to form biofilms (protective layers that shield bacteria from drugs)
    • Multi-drug efflux pumps (systems that pump drugs out of bacterial cells)

    Stenotrophomonas maltophilia

    • Presents as lavender-green or gray in color
    • Negative for oxidase enzyme
    • Can oxidize glucose and maltose
    • Does not ferment lactose
    • Often associated with hospital-acquired infections
    • Trimethoprim/sulfamethoxazole (Bactrim) is typically the most effective treatment option

    Burkholderia

    • Can cause glanders (a serious zoonotic disease)

    Acinetobacter

    • Requires oxygen for growth (aerobic)
    • Does not ferment glucose or lactose
    • Short rod-shaped bacteria observed under a microscope (gram stain)
    • Common in soil and water
    • Responsible for significant hospital-acquired infections (nosocomial)
    • Can cause pneumonia, bloodstream infections (bacteremia), and wound infections
    • Highly resistant to many antibiotics
    • Treatment often requires colistin

    The HACEK Bacteria

    • Includes Eikenella corrodens
    • E. corrodens is a small, fastidious gram-negative rod
    • Found in the mouth (gingiva) and intestines (bowel flora)
    • Positive for oxidase enzyme

    Moraxella species

    • Coccobacillus (short rod-shaped)
    • Associated with bronchitis and pneumonia

    Pasteurella multocida

    • Primarily infects animals but can be spread to humans (zoonotic)
    • Can cause cellulitis (inflammation of skin and subcutaneous tissue) through animal bites
    • Non-motile gram-negative coccobacilli
    • Suspected in skin infections after cat or dog bites
    • Treatment typically involves amoxicillin/clavulanate (Augmentin)

    Yersinia species

    • Infections originate in wild rodents and are transmitted to humans and other mammals
    • Known to cause the bubonic plague (Black Death)
    • Can be used as a biological weapon

    Pseudomonas aeruginosa

    • Common nosocomial pathogen, particularly in moist hospital environments
    • Characterized by sweet, grape-like odor
    • Obligate aerobe, oxidase positive, does not ferment glucose or lactose
    • Grows at 42°C
    • Infections include skin, eye, ear, and serious conditions like VAP, nosocomial pneumonia, and UTI
    • Common in patients with compromised immune systems, such as neutropenic patients, burn patients, cystic fibrosis sufferers, and those on mechanical ventilators
    • Virulence factors include exotoxin A, pili, lipopolysaccharide, and ability to form biofilm
    • Resistant to antibiotics due to beta-lactamase production, biofilm formation, and multi-drug efflux pumps

    Stenotrophomonas maltophilia

    • Known for its lavender green or gray color
    • Oxidase negative, oxidizes glucose and maltose, but does not ferment lactose
    • Primarily a hospital-acquired infection
    • Bactrim (sulfamethoxazole-trimethoprim) is the drug of choice for treatment

    Burkholderia

    • Responsible for glanders, a zoonotic disease affecting humans

    Acinetobacter

    • Aerobic, non-glucose and non-lactose fermenting bacteria
    • Short rods on Gram stain, widely distributed in soil and water
    • Significant cause of nosocomial infections, including pneumonia, bacteremia, and wound infections
    • Highly resistant to antibiotics, often requiring treatment with colistin

    The HACEK Bacteria

    • Group of fastidious Gram-negative bacteria commonly found in the mouth and bowel
    • Includes Eikenella corrodens, a small, oxidase-positive species

    Moraxella species

    • Coccobacilli, commonly associated with bronchitis and pneumonia

    Neisseria Species

    • Includes Neisseria gonorrhoeae (gonorrhea) and Neisseria meningitidis (meningitis)

    Pasteurella multocida

    • Primarily an animal pathogen, but can be zoonotic
    • Commonly transmits via animal bites, leading to cellulitis
    • Non-motile Gram-negative coccobacilli
    • Augmentin (amoxicillin-clavulanate) is the usual treatment

    Yersinia species

    • Infection of wild rodents, transmitted to humans and other mammals
    • Includes Yersinia pestis, the causative agent of plague (black death)
    • Potential biological weapon due to high virulence and transmissibility

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    Description

    Test your knowledge on Pseudomonas aeruginosa and Stenotrophomonas maltophilia, two significant pathogens commonly found in hospital settings. This quiz covers their characteristics, infections they cause, and resistance mechanisms. Ideal for microbiology students and healthcare professionals.

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