MICROBIO 3.7 - INTRACELLULAR BACTERIA

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Questions and Answers

How does the unique developmental style of Chlamydia contribute to its survival and spread?

  • By alternating between metabolically inactive (elementary bodies) and active (reticulate bodies) forms within host cells. (correct)
  • Through rapid replication in extracellular environments, overwhelming the host's immune response.
  • By forming endospores that are resistant to environmental stressors.
  • By producing a thick capsule that protects it from phagocytosis.

Why are special staining procedures like Giemsa stain necessary for visualizing Chlamydia?

  • Chlamydia possesses a thick peptidoglycan layer that is impermeable to standard stains.
  • Chlamydia is gram-negative but poorly retains the counter stain, safranin. (correct)
  • Chlamydia replicates too quickly for standard stains to be effective.
  • Chlamydia's small size requires dyes with higher binding affinity.

A patient presents with follicular conjunctivitis, and their history indicates they live in an area with poor sanitation. Which Chlamydia serovar is most likely the cause?

  • Serovars L1-L3
  • Chlamydophila pneumoniae
  • Serovars D-K
  • Serovars A, B, C (correct)

Which virulence factor allows Chlamydia to thrive within host cells?

<p>Ability to utilize host cell ATP as an energy source. (A)</p> Signup and view all the answers

A sexually active young adult presents with urethritis and is suspected of having a co-infection. Which other pathogen is most likely involved?

<p>Neisseria gonorrhoeae (C)</p> Signup and view all the answers

What is the primary mechanism by which Rickettsia species are transmitted to humans?

<p>Via arthropod vectors such as lice, fleas, mites, and ticks (C)</p> Signup and view all the answers

Why is Coxiella burnetii considered a potential agent for bioterrorism?

<p>It forms spores that can persist in the environment for extended periods. (C)</p> Signup and view all the answers

What clinical manifestation distinguishes Epidemic typhus from Rocky Mountain Spotted Fever (RMSF)?

<p>The involvement of palms and soles in the rash. (A)</p> Signup and view all the answers

A patient who works on a cattle farm presents with flu-like symptoms and atypical pneumonia. Which organism is the most likely cause?

<p>Coxiella burnetii (D)</p> Signup and view all the answers

How does the pathogenesis of Rickettsia infection lead to the characteristic rash observed in many cases?

<p>Rickettsia infects endothelial cells, causing vascular damage and leakage (C)</p> Signup and view all the answers

Which of these bacteria possesses LPS but has a weak endotoxin as a virulence factor?

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

A patient presents with a painless lesion on their genitals followed by lymph node swelling and systemic symptoms. Which Chlamydia serovar is most likely responsible?

<p>Serovars L1, L2, L3 (C)</p> Signup and view all the answers

Which antibiotic would be most appropriate for treating Chlamydophila pneumoniae?

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

A patient is diagnosed with Q fever after exposure to infected farm animals. What characteristic of Coxiella burnetii contributes to the ease of transmission?

<p>It forms endospores resistant to environmental stressors. (B)</p> Signup and view all the answers

A patient presents with a rash that began on their wrists and ankles and spread centrally. They report a recent tick bite. Which organism is most likely responsible?

<p>Rickettsia rickettsii (A)</p> Signup and view all the answers

How does the intracellular lifestyle of obligate intracellular bacteria, like Chlamydia and Rickettsia, impact their susceptibility to antibiotics?

<p>They can only be treated with antibiotics that can penetrate host cells. (D)</p> Signup and view all the answers

What is the role of elementary bodies (EB) in the life cycle of Chlamydia?

<p>To serve as the infectious, metabolically inactive form (D)</p> Signup and view all the answers

Which diagnostic approach would be most effective in differentiating between different species of bacteria?

<p>Using diagnostic/laboratory tests. (A)</p> Signup and view all the answers

Which characteristics are associated with Borrelia burgdorferi?

<p>Spirochete and causes Lyme Disease (D)</p> Signup and view all the answers

What is the significance of understanding the contraindications for antibiotic treatments, such as penicillin?

<p>To avoid adverse reactions in patients with allergies or other medical conditions. (A)</p> Signup and view all the answers

How do virulence factors help pathogens survive in the host?

<p>They help the pathogen subvert the immune system or make the host sick. (A)</p> Signup and view all the answers

Besides Chlamydia and Rickettsia, which other bacteria is also an obligate intracellular organism?

<p>Coxiella (A)</p> Signup and view all the answers

A patient is diagnosed with Lyme disease and reports having other coinfections. Which coinfection is most likely to occur?

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

What is the primary reason for concern regarding the increase in reported cases of Lyme disease?

<p>The potential for long-term, multi-system inflammatory complications. (D)</p> Signup and view all the answers

Flashcards

Obligate Intracellular

Parasites that cannot reproduce outside a host cell.

Elementary Body

Inactive, infectious form of Chlamydia.

Reticulate Body

Active, noninfectious form of Chlamydia.

Inclusion Body

Term for the phagosome containing both reticulate and elementary bodies.

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Obligate Intracellular Bacteria

Chlamydia, Rickettsia, and Coxiella.

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Chlamydiaceae

Small, gram-negative bacteria that are energy parasites and have a unique developmental cycle.

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Infectious Elementary Body

They are phagocytized and contained in a phagosome.

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Elementary Body Transformation.

Changes into a metabolically active form.

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Reticulate Body

Replicates via binary fission.

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Rickettsia spp.

Bacteria transmitted via ticks, lice, and fleas.

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Coxiella burnetii

Can be transmitted by inhaling endospores from animal hides, wastes, etc.

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Lyme disease

A multi-system inflammatory disease.

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Gram-Negative Staining

Gram-negative bacteria that weakly take up safranin, requiring special staining like Giemsa stain.

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Trachoma

Infectious disease caused by Chlamydia trachomatis, leading to follicular conjunctivitis and potential blindness.

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Urogenital Infection

Inflammation of the urethra and reproductive tract, often asymptomatic in females.

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Lymphogranuloma Venereum (LGV)

Sexually transmitted infection caused by specific serovars of Chlamydia trachomatis, leading to buboes and systemic symptoms.

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Chlamydophila pneumoniae Infection

Atypical pneumonia often caused by Chlamydophila pneumoniae, treatable with macrolides.

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Chlamydophila psittaci

Pneumonia transmitted by birds. Can cause necrosis, hemorrhage, and airway obstruction.

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Rocky Mountain Spotted Fever

A disease which has an Ocular involvement commonly.

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Rickettsia

Obligate intracellular bacterial genus which are gram negative.

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Inclusion body

The stage in which the Phagosome containing both reticulate+elementary bodies

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Study Notes

  • Obligate intracellular parasites cannot reproduce outside a host cell
  • Reproduction is entirely reliant on intracellular resources

Gram-Negative Bacteria Characteristics

  • Gram-negative organisms weakly take the counter stain, safranin
  • Special staining procedures such as Giemsa stain are used

Chlamydiaceae

  • These are Gram-negative
  • Display weak endotoxin
  • Use host ATP
  • Can enter non-ciliated columnar, cuboidal, and transitional epithelial cells
  • Includes Chlamydia trachomatis and Chlamydophila pneumoniae

Chlamydia's Developmental Cycle

  • Elementary bodies are metabolically inactive and infectious
  • Reticulate bodies are metabolically active and noninfectious
  • An infectious elementary body is phagocytized and contained in a phagosome
  • Inside the phagosome, the elementary body transforms into a metabolically active reticulate body
  • Reticulate bodies replicate via binary fission
  • Daughter cells reorganize into elementary bodies
  • A phagosome containing both reticulate and elementary bodies is an "inclusion body"
  • The host cell bursts in a couple of days
  • Elementary bodies are released and infect new host cells

Rickettsia spp.

  • Obligate intracellular bacteria
  • Coccobacilli in shape
  • Spread via arthropod vectors like lice, fleas, mites, and ticks

Coxiella burnetii

  • Obligate intracellular rods
  • Technically Gram-negative
  • Highly resistant to environmental stressors including high temperatures and UV light
  • Spreads to humans from mammals like cows
  • Q fever is considered a zoonotic infection
  • A low dosage leads to infection
  • Only 50% of those infected show symptoms
  • Infection can go unnoticed until serious health consequences appear
  • Treated using tetracycline antibiotics

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