Baker/Parks: Infectious Diseases of the Lung Flashcards
Self-limited inflammation of the large* airways of the lung that is characterized by cough without pneumonia
Usually no fever
“Chest cold”
VERY common
Acute bronchitis
What usually causes acute bronchitis?
viruses infleunza A and B parainfluenza virus RSV coronavirus adenovirus
How long must the cough last for it to be acute bronchitis?
more than 5 days
**typically lasts 10-20 days, and sometimes longer than 4 weeks
What will you find on pulmonary exam with a patient with acute bronchitis? What will you find on CXR?
usually normal pulmonary exam, maybe some wheezing
CXR usually normal - not indicated, may see some non-specific bronchial wall thickening
Acute bronchitis is made worse by (blank)
smoking
Should antibiotics be used for acute bronchitis?
NO!!!
**usually viral
T/F: Pneumonia can be caused by bacteria, viruses, and fungus
It causes significant morbidity and mortality
True
**9th leading cause of death in the US
What causes community acquired pneumonia?
bacteria or viruses or both!!
**Think Strep pneumo, H flu, Moraxella catarrhalis, Staph aureus
Predisposing conditions for community acquired pneumonia?
extremes of age
presence of chronic conditions
immune deficiencies
Compare lobar pneumonia to bronchopneumonia in terms of degree and pattern of consolidation
lobar pneumonia - large portion or whole lobe consolidation
bronchopneumonia - patchy consolidation
Four stages of community acquired lobar pneumonia?
- congestion
- red hepatization
- gray hepatization
- resolution
Reaction to inflammation if consolidation extends to the pleura
pleuritis
While there may be complete clearance of infection from the pleura, fibrin may organize and leave (blank)
permanent scarring
Patchy Often mutilobar Sometimes bilateral Lower lobe predominance Similar mechanism Suppurative, neutrophil rich exudate in bronchi, bronchioles and alveolar spaces
bronchopneumonia
Clinical features of community acquired pneumonia
abrupt onset with fever and chills
cough with mucopurulent sputum
may be some pleuritic chest pain
crackles on auscultation, dullness to percussion
Complications of community acquired pneumonia?
pulmonary abscess
infected pleural effusion –> empyema
bacterial dissemination
How to treat community acquired pneumonia?
antibiotics!!!
vaccinate!
thoracentesis for pleural effusion/empyema
Acute, febrile respiratory condition with patchy inflammatory changes in the lungs.
Generally confined to the alveolar septa and pulmonary interstitium
Moderate amount of sputum
No physical findings of consolidation
Only moderately elevated WBC
Lack of alveolar exudate
Atypical pneumonia
What usually causes atypical pneumonia
**most commonly Mycoplasma pneumoniae
also Chlamydia pneumoniae
Influenza A/B, RSV, etc
What distinguishes atypical pneumonia from acute bronchitis?
site of infection!
bronchitis: bronchial wall
atypical pneumonia: alveolar septum and interstititum
In atypical pneumonia, where will you see infiltration of lymphocytes and monocytes?
in the interstitial space!
**around the edges of alveoli
Common in patients with Severe underlying disease Immunosuppression Prolonged antibiotic therapy (resistance) Invasive intravascular access Mechanical ventilation – VERY high risk Potentially life threatening
Hospital acquired pneumonia
What bugs cause hospital acquired pneumonia?
gram negative rods!
pseudomonas aeruginosa, enterobacteriaceae, Klebsiella
Also staph aureus
Inhalation of gastric contents
Debilitated patients
Stroke, intoxication or other causes of altered mental status
Occurs while unconscious or during vomiting
Common in alcoholics
Aspiration pneumonia
How is aspiration pneumonia different from aspiration (chemical) pneumonitis?
multiple organisms are aspirated
these pts get very sick very quickly
possible lung abscess and ARDS as complications
Suppurative destruction of the lung parenchyma within a central area of cavitation, liquefactive necrosis
lung abscess
How do lung abscesses get to the lung?
aspiration post-pneumonic septic emboli from distant infections obstructive (neoplastic conditions) trauma, infected adjacent organs, hematogenous seeding (bacteremia)
How will people with lung abscesses present?
cough
fever
copious foul-smelling purulent sputum
clubbing
Typically localized lesion
Granulomatous inflammatory reaction
Chronic pneumonia
What usually causes chronic pneumonia?
mycobacterium TB
fungi: histoplasma, blastomyces, coccidioides
Clinical presentation and morphology are very similar to TB
Intracelluar parasite of macrophages
Self-limited and latent 1o infection
Chronic progressive 2o disease
Fever, night sweats, cough
Localized extrapulmonary involvement
Wide dissemination in immunocompromised patients
Histoplasmosis
This disease presents like TB, with granuloma formation with caseation necrosis. Granulomas can become fibrotic and calcify.
Histoplasmosis
How do you distinguish histoplasmosis from TB?
yeast on tissue exam
culture
antibody testing
Macrophages have limited ability to ingest and kill this dimorphic fungus
Calls in neutrophils, which leads to suppurative granulomas
Causes pulmonary, disseminated, and primary cutaneous infections
Blastomycosis
How does blastomycosis infect the skin?
when the fungus is directly innoculated to the skin
**can be mistaken for squamous cell cancer due to epithelial hyperplasia
San Joaquin Valley Fever Most in endemic areas have been infected Most primary infections are asymptomatic 10% have lung lesions Fever, cough, pleuritic chest pain Erythema nodosum or Erythema multiformae Granulomatous or pyogenic (suppurative) or both Depends on if spherules remain intact Rupture and release of endospores results in a pyogenic reaction Rarely (
Coccidioidomycosis
Ubiquitous mold that can cause allergies*, invasive lung disease in immunocompromised host, and pulmonary lesions
Aspergillus fumigatus
Risk factors for Mycobacterium TB infection?
poverty
crowding
chronic disease
If you are infected with Mycobacterium TB, do you have disease manifestations?
not always
Primary TB is typically asymptomatic, but it can remain dormant and reactivate when immunity is down
What type of cell-mediated reaction does Mycobacterium TB cause? What do you look for when administering the PPD skin test?
type 4 delayed sensitivity reaction;
look for palpable induration
A lesion seen in the lung that is caused by tuberculosis
The lesions consist of a calcified focus of infection and an associated lymph node.
Ghon complex
**Ghon focus is the calcified region of infection
What will be seen in both the lung and lymph node in a Gohn complex in a patient with TB?
caseous necrosis
For granulomas to develop in TB, what factor is necessary? This explains why Crohn’s disease and RA can cause reactivation of TB
TNF is key!!
This factor activates macrophages and can be used in an assay to test for latent TB
IFN gamma
Secondary (mostly) Reactivation TB
Usually years after Primary Infection when host resistance is down
Can be from an exogenous source
Classic location of lesions is at the apex of the lung
Pre-existing hypersensitivity activates and walls off the infection –> caseous necrosis
Erosion into airways leads to coughing up TB laced sputum
Erosion into blood vessels leads to hemoptysis
Secondary (reactivation) TB
How will patients with reactivation TB present?
malaise, anorexia, weight loss –> CONSUMPTION
fever that is remittant
night sweats
hemoptysis and pleuritic chest pain may be present
What can be done to diagnose TB? What MUST be done?
clinical picture culture acid fast stain of sputum or BAL fluid PCR (nucleic acid testing) for Tb DNA TNF assay
**must identify tubercle bacilli
TB mixed with this immunodeficiency is a bad bad thing
HIV
- *with HIV, you may get false negative sputum or PPD test
- *you have higher bacterial loads, but decreased T cell activity, so you get cavitation and erosion :(
