Pulmonary Infections Flashcards
What is a key physical sign in pneumonia, and what causes it? Give the general mechanism & specific mediators.
Pleuritic chest pain - breathing in expands lungs, stretching pleura, which is sensitized to pain mediators (i.e., bradykinin and PGE2)
Name the 3 types of pneumonia and distinguish how each appears on x-ray.
(1) Lobar: consolidation takes over entire lung (2) Bronchopneumonia: consolidation along small airways, patchy (3) Interstitial: inflammation along interstitium (connective tissue of alveolar sacs), increase in lung markings
Which types of pneumonia are typically due to bacterial versus viral infections?
BACTERIAL: Lobar, bronchopneumonia; VIRAL: Interstitial (aka atypical)
What is most common cause of lobar pneumonia? What is another important cause?
Streptococcus pneumoniae; Klebsiella pneumoniae
How does resolution of lobar pneumonia occur?
Type II pneumocytes are stem cells that regenerate lining of alveolar lung sacs
What is another name for interstitial pneumonia, and why?
Atypical - atypical presentation: relatively mild upper respiratory symptoms (minimal sputum and low fever)
What 3 bacteria are associated with aspiration pneumonia?
Anaerobic bacteria in oropharynx: Bacteroides, Fusobacterium, Peptococcus
What is the most common cause of community-acquired pneumonia? With what kind of pneumonia is it associated?
Streptococcus pneumoniae; Lobar pneumonia
What 3 patient populations are most affected by Klebsiella pneumoniae?
Malnourished and debilitated individuals, especially (1) elderly in nursing homes (2) alcoholics (3) diabetes
What is the most characteristic physical finding of K. pneumoniae, and what causes this?
Red currant jelly sputum due to thick mucoid capsule
What often complicates K. pneumoniae pneumonia?
Abscess
What is the most commonly cause of secondary pneumonia? With what kind of pneumonia is it associated?
Staphylococcus aureus; Bronchopneumonia
What are 2 complications common in S. aureus pneumonia?
(1) Abscess (2) Empyema (pus in pleural space)
Besides S. aureus, what is another common cause of secondary pneumonia? In what other setting does it cause pneumonia?
Haemophilus influenze; pneumonia superimposed on COPD
In what patient population does Pseudomonas aeruginosa commonly cause pneumonia?
Cystic fibrosis patients
Besides H. influenzae, what are 2 causes of community-acquired pneumonia that also cause pneumonia superimposed on COPD?
Moraxella catarrhalis; Legionella pneumophila
Besides COPD patients, in what other patient population does Legionella pneumophila cause pneumonia?
Immunocompromised
How is Legionella pneumophila transmitted?
Water source
What kind of organism is Legionella pneumophila, and how is it best visualized due to this characteristic?
Intracellular organism; Silver stain
What is the most common cause of atypical pneumonia?
Mycoplasma pneumoniae
What patient population does M. pneumoniae usually affect? Give 2 classic examples.
Young adults (e.g., military recruits or college students living in a dormitory)
What is an important complication of M. pneumoniae pneumonia?
Autoimmune hemolytic anemia (IgM against I antigen on RBCs cause cold hemolytic anemia)
How does M. pneumoniae appear on gram stain, and why?
Not visible on gram stain due to lack of cell wall
What is the second most common cause of atypical pneumonia in young adults? Again, what is the first?
Chlamydia pneumoniae; M. pneumoniae
In what context does CMV cause atypical pneumonia?
Posttransplant immunosuppressive therapy
What are 3 patient populations in which Influenza virus causes atypical pneumonia?
(1) Elderly (2) Immunocompromised (3) Preexisting lung disease
For what does pneumonia due to influenza virus increase the risk? Why is this important?
Increases risk for superimposed S. aureus or H. influenzae bacterial pneumonia; Most patients with flu virus do not die from virus itself, instead virus weakens immune system allowing secondary pneumonia to kill them
What kind of pneumonia does Coxiella burnetii cause? What is its characteristic presentation? What is the name for this?
Atypical pneumonia; high fever (Q fever)
In what 2 patient populations is atypical pneumonia due to Coxiella burnetii seen?
(1) Farms (2) Veterinarians (Coxiella spores are deposited on cattle by ticks or are present in cattle placentas)
To what group of bacteria does Coxiella belong? In what 3 ways is it distinct from this group?
Rickettsial organism; (1) causes pneumonia (2) not require arthropod vector for transmission (survives as highly heat-resistant endospores) (3) not produce skin rash
How does aspiration pneumonia present, and why?
Right lower lobe abscess; Right main stem bronchus branches at a less acute angle than the left
What are 4 common sites/conditions of systemic spread of Tb?
(1) Meninges (meningitis) (2) Cervical lymph nodes (3) Kidneys (sterile pyuria) (4) Lumbar vertebrae (Pott disease)
To where in the CNS does Tb spread? Be specific.
Meninges at base of brain
