Pneumonia Flashcards
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
When and who is most likely to get CAP?
Can happen year round, but mostly in winter, mostly people with age >65
What are “typical” pathogens of CAP?
S. pneumoniae, H. influenzae, M. catarrhalis, S. aureus
What are the risk factors for severe S. pneumoniae disease?
- Asplenia - failure to clear capsular organisms
2. Abnormal immunoglobulin response (myeloma, lymphoma, HIV) - failure to bind Ab to capsule
What are the risk factors for S. aureus CAP?
Elderly, or post-influenza in normal adults
What is the clinical presentation of atypical pneumonias?
Low grade fever, mild respiratory illness, dyspnea, non-productive cough, in yonug adults
What is seen on chest Xray for atypical pneumonias? Gram stain?
Typically diffuse lung disease, except Legionella may be focal
Gram stain: Nothing appears
What are the specific features of Mycoplasma pneumoniae? Is it transmitted person to person?
Walking pneumonia, sore throat is initial finding, X-ray looks way worse than it actually is
Yes, transmitted person to person
What is one specific finding that happens in about 5% of Mycoplasm pneumoniae?
Bullous myringitis -> inflammation of the tympanic membrane
What is a common chest X-ray finding for Chlamydia pneumonia?
Multi-lobar findings with gradual progression
What do viruses typically cause in terms of respiratory infections?
Acute bronchitis in children, but can also be seen in adults and set the stage for bacterial superinfection
Which virus causes bronchiolitis in children <2 years?
RSV
What other common viruses seed bacterial infections?
Influenza, parainfluenza type 3, adenovirus, CMV in immuncompromised host
What is HAP vs VAP?
Nosocomial pneumonias
HAP - Hospital-acquired pneumonia (>48 hours post admission)
VAP - Ventilator-associated pneumonia (>48 hours after intubation)
What microbes are frequently implicated in nosocomial pneumonias, and do we worry about Candida?
Gram negative aerobes (Pseudomonas, Acinetobacter)
MRSA
Candida is often cultured, but does NOT cause disease and should not be treated
What are the two most common patient populations which have TB?
- HIV+
2. Patients receiving TNF inhibitors
What are the clinical features of TB?
Indolent course
Fever, dry cough, weight loss, nightsweats, hemoptysis
Where is TB commonly found?
Upper lung lobe, from reactivation, due to high oxygen tension
What are three risk factors for Aspergillosis pneumonia?
- Neutropenia
- Prolonged, high dose steroid use
- Chronic granulomatous disease
What are the clinical features of aspergillosis pneumonia?
Fever, pleuritic chest pain, cough with hemoptysis
What are the X-ray features of aspergillosis?
Nodular lesions with “halo sign” that often progresses to cavities
What is seen on biopsy of aspergillosis?
Acute angle branching hyphae, It is often a contaminant of sputum culture unless a high risk patient
Which of the endemic fungi is most likely to disseminate, and how are they often detected?
Blastomycosis disseminates in normal hosts at times, but they can all disseminate in immunocompromised.
Detect via urine antigen
What does chest X-ray for PCP pneumonia cause?
Diffuse interstitial disease, but may be normal
What are the clinical features of PCP pneumonia?
Indolent clinical course, mild cough with minimal sputum, and progressive dyspnea and hypoxia
What lab is usually elevated in PCP pneumonia?
Serum beta-glucan
