Pneumonia Flashcards
(49 cards)
What is pneumonia vs bronchitis vs bronchiolitis?
Pneumonia - infection of the lung parenchyma
Bronchitis - inflammation of the medium to large airways
Bronchiolitis - Inflammation of small airways (children <2 years)
What is the most common cause of infection related mortality?
pneumonia
Are the airways below the larynx sterile? Why?
No, but microbial levels are low because they are cleared by cilia, humoral immunity (IgA), and cellular immunity (phagocytosis)
What are two ways host defenses can be disrupted and acute pneumonia can arise?
- Presence of especially virulent organisms
2. Large inoculum
What is microaspiration?
A common way of acquiring pneumonia, when epithelial surfaces of upper airway are colonized
What are some factors that interfere with normal host defenses?
- Ciliary disruption - i.e. viral infection or cigarettes
- Altered consciousness - i.e. alcohol, or especially when intubated
- Iatrogenic manipulation - bronchoscopies
Why do older people often get pneumonia?
Diminished ciliary clearance, abnormal elastic recoil of lungs, and diminished T and B cell response
What are the three most common symptoms of pneumonia?
- Cough
- Shortness of breath
- Chest pain - pleuritic (pain on inspiration)
What are the four most common clinical signs of pneumonia?
- Fever
- Tachypnea
- Tachycardia
- Purulent sputum
Why does poor dentition put you at risk for pneumonia?
Aspiration of anaerobes from abscesses is a common source of infection
What are two chest signs on physical exam that point to pneumonia?
- Chest splinting - cannot expand on both sides
2. Evidence of consolidation - i.e. dullness, egophony, bronchophony, crackles
What are two lab signs that point to pneumonia?
- Elevated white cell count with left shift
2. High inflammatory markers (procalcitonin, C-reactive protein)
What is a left shift of WBC?
more band form PMNs found -> indicates rapid production of PMNs and likely infection
What are two common patterns of Chest X-rays for pneumonia?
- Lobar consolidation
2. Diffuse interstitial
What is the most sensitive test for pneumonia and when do you order it?
CT of chest
For very sick / immunocompromised only, due to expensive and radiation exposure
What is the definition of a good sputum sample?
<10 epithelial cells and >25 PMNs per low power field
What is the sensitivity / specificity of gram staining for pneumonia? What organisms would not be picked up?
85% Organisms not picked up: Atypicals Bacterial - Mycoplasma, Mycobacteria, Legionella Viral - Influenza Fungal - PCP
What stains can be used to visualize TB?
Ziehl-Neelsen, or Auramine-rhodamine fluorescent stain
What is the morphology of Moraxella catarrhalis and who does it most commonly affect?
Gram negative diplococci
Affects COPD patients and elderly, much like Moraxella catarrhalis
Why can sputum culture be misleading?
S. pneumoniae will always be significant, but organisms like E. coli may just be colonizers
What are the sputum consistencies / features for mixed anerobic aspiration pneumonia vs pneumococcal pneumonia?
Mixed anaerobic - foul smelling
Pneumococcal - rusy colored
Why is a blood culture useful for pneumonia?
If positive (20%), proves etiology and can be used to test susceptibility of the organism
What are two urine antigen tests that are always used and why are they appealing?
Very quick turnaround - 1 hour
- Pneumococcal urine antigen
- Legionella urine antigen (serotype 1)
When do you use bronchoscopy with bronchoalveolar lavage? Lung biopsy?
Not unless diagnosis is in doubt / patient is not improving, but it is minimally invasive
Lung biopsy - rare, only as last resort because highly invasive
