Pulmonary Infections Flashcards
What pneumonia causing bacteria are best recognized for their ability to cause bronchopneumonia?
•what aboutlobar pneumonia?
In general Bronchopneumonia is caused by things like:
• Staph aureus
• H. influenzae
• Pseudomonas aeurginosa
• Moraxella catarrhalis
In general lobar pneumonia is caused by:
• Strepococcus pneumoniae
• Klebsiella pneumoniae
• H. flu
What bug is shown in this sputum sample?
Strep. Pneumo. - this bug is a gram negative lancet shaped diplococcus
Shown below is what a normal pneumonia looks like microscopically in the lung
What are the 4 stages in the inflammatory response to pneumonia?
- Congestion - vessels get engorged and get edematous with abundant bacteria
- Red Hepatization - Massive congestion with tons of PMNs (probably recruited by IL-8 from endothelial damage and C5a from complement, remember they )
3. Gray Hepatization - macrophages invade and degrade RBC’s to created hemosiderin and fibropurulent exudate
- Resolution - Enzymatic digetestion (MMPs) and Resorption by macrophages
What is demonstrated in the left and right images?
Right:
PMN infiltrate with congestion in the alveoli
Left:
Macrophages entraped in the fibropurulent exudate they are releasing
Note: image shown here shows red hepatization on the left with all of the congestion with blood. Right shows grey-hepatization that is occuring at the edges of the lesion due to macrophage infiltration
What pathogens are most associated with necrotizing pneumonia?
Klebsiella pneumoniae and Staph (gupta notes say strep, but I don’t think its correct)
What is shown here?
Pulmonary abscess (most commonly caused by kleb and staph)
Gross picture is shown below
What is shown here? Key features?
This is an Atypical pneumonia, you can tell this by the lymphocytic infiltrate (pointed out by the red arrows) and the type II pneumocyte hyperplasia pointed out with yellow arrows
What is the most typical cause of Atypical Pneumonia?
Viruses:
• Flu, RSV, CMV
Bacteria:
• Clamydia pneumoniae, Mycoplasma pneumoniae, Legionella
How do you diagnose legionella (gram negative, falcultative intracelluar rod)?
• why does Gupta not classify this as atypical?
Dx:
• Urine Antigen Test or PCR
• Culture on charcoal yeast extract agar with CYSTEINE and IRON
Infiltrate is neutrophilic - note: as seen here legionella can also cause small vessel vasculitis
What type of pneumonia is this?
• how do you know?
Aspiration pneumonia, you can tell by the presence of the foriegn body giant cells (these are seen around sutures etc.)
What is aspiration pneumonia?
Aspiration of gastric contents causes severe irritation of respiratory epithelium and alveoli. In addition much of the oral and gastric flora gets down there and you get a MIXED aerobic and anerobic infection. This causes very foul smelling sputum with risk of abscess formation.
Describe primary TB with regard to:
• how often clinical disease develops
• where infection is most likely to take place
• how long does it take our immune system to respond, why?
primary TB only develops into clinically relevant disease in about 5% of cases. Infection typically takes place in the lower lobe. It typically takes TH1 cells about 3 weeks to respond to this stimulus because TB is good at killing macrophages.
What is shown here?
Ghon complex seen here is pathopneumonic for primary pulmonary TB. Complex is a grey-white parenchymal focus
What are these arrows pointing out in these caseating TB lesions?
Langhans Giant Cells
What infection is shown here?
MTB
Where is secondary TB usually found?
• how does it ever reactivate?
Secondary TB:
Typically found at the lung APEX
Reactivation occurs because someone becomes immunocompromised OR they just get reinfected if they live in an endemic area
Is this TB most likely primary or secondary?
Most likely SECONDARY because the granuloma is seen at the apex (this is different than the ghon focus that we see where the caseation is perihilar)
What is shown here?
This is histoplasmosis. We see macrophages filled with tiny (3-5 µm) thin-walled yeast
T or F: histoplasmosis may present very similarly to TB.
True
What is this?
Broad Based Bud - Blastomycosis
What fungus is this?
Histoplasmosis
What is this?
• key features?
Cryptococcus neoformans - you can see halos on some of the cells (this is unique to crypto). If stained with india ink a think cryptococcus capsule shows
What is the key virulence factor of this fungus?
Key factor - antiphagocytic capsule
What is this?
• key features?
Coccidioidomycosis - thick-walled, non-budding 20-60µm spherules filled with endospores
What is this?
• key features?
Who get pneumonia from CMV?
People that are immunocompromised (transplant pts, HIV, chemo.)
What are the AIDS determining pneumonias?
AIDS determining pneumonias:
• PCP (pneumocystis jiroveci)
• CMV (cytomegalovirus)
• MAC (mycobacterium avium)
• TB
What is this?
Pneumocystic jiroveci - foamy appearance on H and E
• notice on silver stain below the crushed ping-pong ball appearance caused by the central umbilications
*Note that this isn’t invasive so its just hanging out in the alveoli
Describe what you see?
Angioinvasion of regular septate hyphae with progressive acute-angle branching
What is interesting about the aspergillus infection shown here?
Its abilities for angioinvasion allow it to cross lobes
What is a huge risk factor for the disease shown here?
People in diabetic ketoacidosis can get mucor mycosis infections and rapidly deteriorate
What fungus most often produces residual pulmonary calcification?
Histoplama capsulatum
Differentiate a Touton giant cell from a Langhans giant cell?
• how do the conditions in which we see these things differ?
Touton Giant Cell:
• Nuclei form a ring and outside the cytoplasm is foamy
•these form in lipid laden lesions likefat necrosis
Langhans Giant Cell:
- Very often found in TB but not pathopneumonic
- Nuclei arranged in a ring
**Touton cell shown below
Differentiate a foriegn body giant cell from a Langhans cell.
Foreign Body Giant Cell:
• Nuclei are CENTRALLY located and overlapping
• Formed in response to talc or sutures usually
Langhans:
• Nuclei are located at the PERIPHERY
**Langhans cell shown below
