February 9, 2016 - Microbiology and Pathology Flashcards Preview

COURSE 3 > February 9, 2016 - Microbiology and Pathology > Flashcards

Flashcards in February 9, 2016 - Microbiology and Pathology Deck (13):

Spread of Organisms to Alveoli

1) Aspiration of the oropharynx

2) Inhaled droplets or airborne particles

3) Hematogenous spread

4) Contiguous spread


Stages of Lobar Pneumonia

Congestion - Day 1/2

Rep Hepatization - Day 3/4 - Blood cells, neutrophils, and fibrin make their way into the pulmonary alveoli.

Grey Hepatization - Day 5-7 - The blood cells are broken down leaving a fibrinosuppurative exudate.

Recovery - Day 8-21


Red Hepatization

The second stage of lobar pneumonia. The lungs are filled with red cells.

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Grey Hepatization

The third stage in lobar pneumonia when the red cells and infiltrate have been broken down, leaving a thick exudate.

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Interstitial Pneumonia

Is a form of interstitial lung disease.

Infiltrates in the alveolar walls, but an absence of alveolar exudate.

Can cause scarring of the lungs.


Common Organisms of Community Acquired Pneumonia

Streptococcus pneumoniae

Haemophilus influenzae

Moraxella catharralis

Klebsiella pneumoniae


Common Organisms of Healthcare Acquired Pneumonia

Staphylococcus aureus (including MRSA)

Pseudomonas auruginosa

E. coli

Other Gram-negative bacteria


Typical vs. Atypical Pneumonia

Typical pneumonia is often caused by the typical pathogens and usually causes lobar pneumonia, has a more acute onset, and has a productive cough.

Atypical pneumonia is often caused by atypical pathogens and can cause interstitial pneumonia. It's onset is usually more insidious and has a dry cough.


Streptococcus pneumoniae

Gram positive cocci (often in pairs or chains)

The most common cause of CAP

Encapsulated organism

Found in the nasopharynx

20-30% of patients will have bacteremia

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Pneumococcal Vaccines

Targets antigens on the capsule of Strep. pneumo.

Different types. Recommend for patients over 65.


Common Organisms of Atypical Pneumonia

Chlamydophila pneumoniae

Mycoplasma pneumoniae

Legionella pneumophila


Usually have a less acute onset and an interstitial pattern.


Aspiration Pneumonia

Caused by aspiration.


Typically a mix of upper airway and oral flora. The big thing, is that anaerobes tend to be present and you need to account for them in your antibiotic selection.


"Other" Causes of Pneumonia

Francisella tularensis - Exposure to infected rodents, rabbits, or caribou

Bacillus anthracis - Exposure to infected animals / inhalation of spores

Coxiella burnetti - Exposure to infected sheep

Chlamydia psittaci - Bird exposures (often parakeets)

Hantavirus - Exposure to mouse droppings

Endemic fungi - Specific travel history

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