Medical Microbiology: Pseudomonas and Allies
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Questions and Answers

What is the main pathogen in humans discussed in the content?

  • Pseudomonas aeruginosa (correct)
  • Stenotrophomonas maltophilia
  • Burkholderia
  • Acinetobacter

Pseudomonas aeruginosa is an obligate anaerobe.

False (B)

What color is Stenotrophomonas maltophilia?

Lavender green or gray

What is the drug of choice for treating Stenotrophomonas maltophilia?

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

Pseudomonas aeruginosa does not ferment ______.

<p>glucose, lactose</p> Signup and view all the answers

Which of the following is a serious pathogen associated with Pseudomonas aeruginosa?

<p>Ventilator-associated pneumonia (A)</p> Signup and view all the answers

What are the virulent factors for Pseudomonas aeruginosa?

<p>Exotoxin A, pili, lipopolysaccharide, chronic colonization</p> Signup and view all the answers

Acinetobacter is a glucose fermenter.

<p>False (B)</p> Signup and view all the answers

What infection can Pasturella multocida cause from animal bites?

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

What is a hallmark of Bacteroides fragilis infections?

<p>Aspiration pneumonia (B)</p> Signup and view all the answers

Yersinia species can cause ______ disease in humans.

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

What body systems can Pseudomonas aeruginosa infect?

<p>Urinary (A), Skin (B), Respiratory (C)</p> Signup and view all the answers

What type of toxin does Pseudomonas aeruginosa produce that inhibits protein synthesis?

<p>Exotoxin A</p> Signup and view all the answers

Which diagnostic method is used for the isolation of Pseudomonas aeruginosa?

<p>Cetrimide agar (C)</p> Signup and view all the answers

Pseudomonas aeruginosa is only found in hospital environments.

<p>False (B)</p> Signup and view all the answers

What is a notable environmental concern caused by Pseudomonas aeruginosa?

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

Which of the following treatment options is commonly used for Pseudomonas aeruginosa infections?

<p>Piperacillin-tazobactam (D)</p> Signup and view all the answers

What mechanism does Pseudomonas aeruginosa employ to inactivate penicillins?

<p>Production of β-lactamases</p> Signup and view all the answers

Which treatment strategy is often required due to antibiotic resistance in Pseudomonas aeruginosa?

<p>Combination therapy (D)</p> Signup and view all the answers

Efflux pumps in Pseudomonas aeruginosa help retain antibiotics within the bacteria.

<p>False (B)</p> Signup and view all the answers

Study Notes

Pseudomonas aeruginosa

  • Common nosocomial pathogen (moist hospital areas)
  • Obligate aerobe with distinct sweet, grape-like odor
  • Oxidase positive, non-fermenter of glucose and lactose
  • Grows at 42°C
  • Motile, found in water, plants, and animals
  • Causes skin, eye, and ear infections
  • Can cause serious infections like ventilated-associated pneumonia (VAP), nosocomial pneumonia, and urinary tract infections (UTIs)
  • High risk for neutropenic, burn, cystic fibrosis, and mechanically ventilated patients
  • Virulence factors: exotoxin A, pili, lipopolysaccharide, and chronic colonization
  • Resistance mechanisms include beta-lactamase production, biofilm formation, and multi-drug efflux pumps

Stenotrophomonas maltophilia

  • Distinct lavender green or gray color
  • Oxidase negative, oxidizes glucose and maltose, but doesn't ferment lactose
  • Associated with hospital-acquired infections
  • Treated with Bactrim

Burkholderia

  • Causative agent of glanders, a zoonotic disease

Acinetobacter

  • Aerobic, non-glucose and non-lactose fermenting, short rod-shaped bacteria commonly found in soil and water
  • Significant nosocomial pathogen, causing pneumonia, bacteremia, and wound infections
  • Highly resistant, often requiring treatment with colistin

The HACEK Bacteria

  • Includes Eikenella corrodens, a small, fastidious, oxidase-positive gram-negative rod
  • Found in gingival and bowel flora

Moraxella species

  • Coccobacilli associated with bronchitis and pneumonia

Neisseria Species

  • Includes Neisseria gonorrhoeae, a sexually transmitted infection causing gonorrhea
  • Includes Neisseria meningitidis, a causative agent of meningitis

Pasteurella multocida

  • Primarily an animal pathogen, but can be zoonotic
  • Causes cellulitis from animal bites
  • Non-motile gram-negative coccobacilli, strongly suspected in skin infections from cats and dogs
  • Treated with Augmentin

Yersinia species

  • Infections from wild rodents, transmissible to humans and other mammals
  • Includes Yersinia pestis, the causative agent of the black death (bubonic plague)
  • Can be utilized as a biological weapon

Y. enterocolitica and Y. pseudotuberculosis

  • Cause diarrheal disease in humans
  • Non-lactose fermenting

Haemophilus influenzae type B

  • Possesses an antiphagocytic capsule, with type B being the most virulent for humans
  • Its major virulence factor is the polyribose phosphate capsule
  • Causes non-invasive infections like otitis media, sinusitis, and pharyngitis
  • Can cause invasive infections such as pneumonia, septic arthritis, and osteomyelitis
  • Preventable with vaccination

Bacteroides fragilis

  • Part of the normal intestinal flora, but can be pathogenic in synergy with other bacteria
  • Causes polymicrobic infections
  • Virulent factor is its capsular polysaccharide
  • Facultative anaerobe, known for causing aspiration pneumonia and intra-abdominal abscesses
  • Treated with metronidazole or clindamycin

Haemophilus

  • Small pleomorphic bacteria requiring enriched chocolate agar (contains no chocolate) for growth
  • Requires X (heme) and V (nicotinamide adenine dinucleotide) factors for growth
  • Found in normal respiratory flora
  • Causes a wide range of diseases

Pseudomonas aeruginosa

  • An opportunistic pathogen found in a wide range of environments, including hospitals.
  • Frequently infects individuals with compromised immune systems, burn victims, patients with cystic fibrosis, and those with chronic lung diseases.
  • Causes infections in diverse areas of the body, such as the respiratory system, urinary tract, bloodstream, and skin.
  • Possesses a variety of virulence factors that enable it to evade the host’s defenses and cause harm:
    • Produces exotoxins: specifically, exotoxin A inhibits protein synthesis.
    • Secretes enzymes: elastase and proteases degrade host tissues, facilitating tissue damage.
    • Forms biofilms: enhancing survival in hostile environments, such as the body's immune system.
  • Commonly diagnosed by collecting clinical specimens from infected sites (e.g., sputum, wounds, urine) and culturing them on selective media (like cetrimide agar).
  • Can be identified using biochemical tests, like the oxidase test, which is positive for Pseudomonas aeruginosa, and tests for its utilization of citrate as its sole carbon source.
  • Advanced techniques like PCR and MALDI-TOF provide quicker and more accurate identification.
  • A prevalent bacterium in the environment, found in soil, water, and diverse settings, including hospitals.
  • Utilized in bioremediation due to its ability to degrade pollutants.
  • Known for forming biofilms in aquatic environments, such as pipelines and water systems, contributing to biofouling in industrial processes and natural ecosystems.
  • Treatment typically involves the use of broad-spectrum antibiotics like piperacillin-tazobactam, cephalosporins (cefepime), and carbapenems (meropenem).
  • Combination therapy might be required due to the prevalence of antibiotic resistance.
  • Antibiotic susceptibility testing is crucial to guide treatment selection.
  • Alternative treatments, like phage therapy and immunotherapy, are being investigated for their potential to combat Pseudomonas aeruginosa infections.
  • Significantly resistant to numerous antibiotics, complicating treatment efforts.
  • Several mechanisms contribute to its resistance:
    • Production of β-lactamases: these enzymes inactivate penicillins and cephalosporins.
    • Efflux pumps: these pumps expel a range of antibiotics from the bacterial cell, preventing them from reaching their target.
    • Modifications to target sites: changes in penicillin-binding proteins can obstruct antibiotics from binding and inhibiting bacterial cell wall synthesis.
    • Resistance plasmids: these plasmids allow for horizontal gene transfer among bacterial populations, facilitating the spread of drug resistance.

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Description

Test your knowledge on Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Burkholderia. This quiz covers their characteristics, pathogenicity, and clinical significance, particularly in nosocomial infections. Understand their virulence factors and resistance mechanisms to better prepare for medical microbiology scenarios.

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