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Immunology / Micro > Pneumonia > Flashcards

Flashcards in Pneumonia Deck (49):
1

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)

2

What is the most common cause of infection related mortality?

pneumonia

3

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)

4

What are two ways host defenses can be disrupted and acute pneumonia can arise?

1. Presence of especially virulent organisms
2. Large inoculum

5

What is microaspiration?

A common way of acquiring pneumonia, when epithelial surfaces of upper airway are colonized

6

What are some factors that interfere with normal host defenses?

1. Ciliary disruption - i.e. viral infection or cigarettes
2. Altered consciousness - i.e. alcohol, or especially when intubated
3. Iatrogenic manipulation - bronchoscopies

7

Why do older people often get pneumonia?

Diminished ciliary clearance, abnormal elastic recoil of lungs, and diminished T and B cell response

8

What are the three most common symptoms of pneumonia?

1. Cough
2. Shortness of breath
3. Chest pain - pleuritic (pain on inspiration)

9

What are the four most common clinical signs of pneumonia?

1. Fever
2. Tachypnea
3. Tachycardia
4. Purulent sputum

10

Why does poor dentition put you at risk for pneumonia?

Aspiration of anaerobes from abscesses is a common source of infection

11

What are two chest signs on physical exam that point to pneumonia?

1. Chest splinting - cannot expand on both sides
2. Evidence of consolidation - i.e. dullness, egophony, bronchophony, crackles

12

What are two lab signs that point to pneumonia?

1. Elevated white cell count with left shift
2. High inflammatory markers (procalcitonin, C-reactive protein)

13

What is a left shift of WBC?

more band form PMNs found -> indicates rapid production of PMNs and likely infection

14

What are two common patterns of Chest X-rays for pneumonia?

1. Lobar consolidation
2. Diffuse interstitial

15

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

16

What is the definition of a good sputum sample?

<10 epithelial cells and >25 PMNs per low power field

17

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

18

What stains can be used to visualize TB?

Ziehl-Neelsen, or Auramine-rhodamine fluorescent stain

19

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

20

Why can sputum culture be misleading?

S. pneumoniae will always be significant, but organisms like E. coli may just be colonizers

21

What are the sputum consistencies / features for mixed anerobic aspiration pneumonia vs pneumococcal pneumonia?

Mixed anaerobic - foul smelling

Pneumococcal - rusy colored

22

Why is a blood culture useful for pneumonia?

If positive (20%), proves etiology and can be used to test susceptibility of the organism

23

What are two urine antigen tests that are always used and why are they appealing?

Very quick turnaround - 1 hour
1. Pneumococcal urine antigen
2. Legionella urine antigen (serotype 1)

24

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

25

When and who is most likely to get CAP?

Can happen year round, but mostly in winter, mostly people with age >65

26

What are "typical" pathogens of CAP?

S. pneumoniae, H. influenzae, M. catarrhalis, S. aureus

27

What are the risk factors for severe S. pneumoniae disease?

1. Asplenia - failure to clear capsular organisms
2. Abnormal immunoglobulin response (myeloma, lymphoma, HIV) - failure to bind Ab to capsule

28

What are the risk factors for S. aureus CAP?

Elderly, or post-influenza in normal adults

29

What is the clinical presentation of atypical pneumonias?

Low grade fever, mild respiratory illness, dyspnea, non-productive cough, in yonug adults

30

What is seen on chest Xray for atypical pneumonias? Gram stain?

Typically diffuse lung disease, except Legionella may be focal

Gram stain: Nothing appears

31

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

32

What is one specific finding that happens in about 5% of Mycoplasm pneumoniae?

Bullous myringitis -> inflammation of the tympanic membrane

33

What is a common chest X-ray finding for Chlamydia pneumonia?

Multi-lobar findings with gradual progression

34

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

35

Which virus causes bronchiolitis in children <2 years?

RSV

36

What other common viruses seed bacterial infections?

Influenza, parainfluenza type 3, adenovirus, CMV in immuncompromised host

37

What is HAP vs VAP?

Nosocomial pneumonias
HAP - Hospital-acquired pneumonia (>48 hours post admission)
VAP - Ventilator-associated pneumonia (>48 hours after intubation)

38

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

39

What are the two most common patient populations which have TB?

1. HIV+
2. Patients receiving TNF inhibitors

40

What are the clinical features of TB?

Indolent course
Fever, dry cough, weight loss, nightsweats, hemoptysis

41

Where is TB commonly found?

Upper lung lobe, from reactivation, due to high oxygen tension

42

What are three risk factors for Aspergillosis pneumonia?

1. Neutropenia
2. Prolonged, high dose steroid use
3. Chronic granulomatous disease

43

What are the clinical features of aspergillosis pneumonia?

Fever, pleuritic chest pain, cough with hemoptysis

44

What are the X-ray features of aspergillosis?

Nodular lesions with "halo sign" that often progresses to cavities

45

What is seen on biopsy of aspergillosis?

Acute angle branching hyphae, It is often a contaminant of sputum culture unless a high risk patient

46

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

47

What does chest X-ray for PCP pneumonia cause?

Diffuse interstitial disease, but may be normal

48

What are the clinical features of PCP pneumonia?

Indolent clinical course, mild cough with minimal sputum, and progressive dyspnea and hypoxia

49

What lab is usually elevated in PCP pneumonia?

Serum beta-glucan

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