Bacterial Pneumonia 2 (6) Flashcards

1
Q

What is the bacteriology or Legionella?

A

Poorly staining gram (-) rods

Facultative intracellular parasite

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2
Q

What are the two “phases” of Legionella bacteria?

A

Infectious phase: free- lining motile with flagella

Replicative phase: intracellular nonmotile

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3
Q

What is the natural lifestyle of legionella?

A

Form biofilms in stagnant freshwater–> parasitize protozoa–> complete full life cycle

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4
Q

What is the unnatural lifestyle of legionella?

A

Form biofilms in HVAC systems–> enters human lungs–> parasitize alveolar macrophages–> dead end

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5
Q

What occurs when humans breath in/ aspirate water contaminated with legionella?

A

1- asymptomatic seroconversion

2- Pontiac fever

3- Legionnaires Disease

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6
Q

What are the steps in the pathogenesis of legionella?

A

1- Taken up by macrophages

2- Contained in an altered phagosome

3- T4SS fusion with lysosome and replicates within the phagosome

4- Becomes motile and escapes phagosome

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7
Q

Virulence factors/gene loci of legionella?

A

1- mip: invade monocytes

2- Dot/ Icm locus: T4SS

3- PilE and PilD: pilus formation (attachment)

4- Mac/ pmi/ Mil: unknown function

5- Pep/ Pro: Zinc metalloprotease (escape from phagosome)

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8
Q

Describe Pontiac fever?

A

Present hours- 2 days after exposure

Flu like symptoms

Patient previously healthy

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9
Q

What generates the symptoms in pontiac fever?

A

Symptoms are immunogenic…as the immune system kills live and or clears dead bacteria

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10
Q

What are the risk factors for developing legionnaires disease?

A

Patient is previously ill, elderly, immunosuppressed, diabetic, has heart/ lung disease, smokes, has kidney disease, has alcohol at time of exposure

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11
Q

What are the symptoms of Legionnaires disease?

A

Pneumonia w/ kidney involvement and diarrhea

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12
Q

What are key factors in the history to look for when diagnosing Legionnaires disease?

A

Male, elderly, pre-existing malfunction or swallowing, immunity or respiratory systems

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13
Q

What are the lab tests to Dx Legionella infections?

A

Urine antigen tests–> quicly detects LP1 strain (90% of US infections)

Culture–> requires special nutrients, slow, needed to trace outbreaks

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14
Q

What is the treatment for pontiac fever?

A

Usually resolves without treatment

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15
Q

What is the treatment for legionnaires disease?

A

Admit to the hospital

Fluoroquinolones, doxy, azithromycin, or macrolides

Supportive care for recovery

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16
Q

What is the bacteriology of C. burnetii?

A

Proteobacteria (related to legionella)…related to legionella

Extremely infectious!!

17
Q

Virulence factors of C. burnetii?

A

Acid phophatase and superoxide dismutase–> help bacteria survive in FUSED lysosome-endosome

18
Q

Where is C. burnetii common?

A

Netherlands, France, Spain and Iraq

19
Q

What organs does C. burnetii infect though “trojan horse” macrophages?

A

Liver, spleen, bone marrow

20
Q

What are the symptoms of a C. burnetti infection?

A

Pneumonia and Hepatitis!

also: fever, HA, chills, sweats, dry cough

21
Q

Treatment for C. burnetti infection?

A

Doxycyclines or fluoroquinolones

Can be prevented with vaccine

22
Q

What is the bacteriology of mycoplasma pneumoniae?

A

Smallest free living organism

Strictly aerobic

No cell wall

Cell membrane contains cholesterol

23
Q

How many serotypes are there of mycoplasma pneumoniae?

A

only 1…but immunity is incomplete

24
Q

What is the pathogenesis of Mycoplasma pneumoniae?

A

Pathogenic only to humans and transmitted by respiratory droplets

In lungs it assumes a rod shape…P1 adhesion binds to respiraoty epithelium

25
Q

What diseases are caused by Mycoplasma pneumoniae?

A

Tracheobronchitis, bronchiolitis, Atypical pneumonia (walking pneumonia)

26
Q

Why can Mycoplasma pneumonia cause anemia?

A

Cold agglutinins that attack and destroy RBCs

27
Q

What are the virulence factors of Mycoplasma pneumoniae?

A

P1 adhesion

CARDS endotoxin

Bacterial metabolism produces hydrogen peroxide (which damages tissue)

28
Q

Symptoms of Mycoplasma pneuominiae?

A

Nonproductuve cough, sore throat, earache, small amounts of whitish sputum, fever, HA, myalgia, malaise

29
Q

What will a CXR for Mycoplasma pneumoniae show?

A

Prominent infiltrates

30
Q

What are the lab tests used to Dx Mycoplasma pneumoniae?

A

Not usually required

Culture is possible but requires special media

Serology for cold agglutinings

Complement fixation shows increased in specific antibodies

31
Q

Treatment for Mycoplasma pneumoniae?

A

Macrolides or tetracyclines or fluoroqunolones

Extended course of treatment (10-14 days) because it is slow growing