CAP-PE Pathology - Truwit Flashcards Preview

M2 Renal/Respiratory > CAP-PE Pathology - Truwit > Flashcards

Flashcards in CAP-PE Pathology - Truwit Deck (26):

Rust-colored sputum is classic for which pathogen?

Streptococcus pneumoniae


E/A changes heard on auscultation of the lungs indicate what?



What is the most common etiology of CAP?

Unknown. The responsible pathogen is not identified approximately 50% of the time.

The sputum gram stain and culture are often discordant, or multiple agents (including atypicals) are present

If the pathogen *is* identified, it is most often streptococcus pneumoniae


Why is an atypical pneumonia "atypical"?

The pathogen is atypical

Also: sputum, physical findings of consolidation, WBC elevation, and alveolar exudate may be absent

This is not unique however - Hx, PEx, and CXR usually are unhelpful in differentiating atypical pneumonia from CAP


Name the (4) major atypical bugs of pneumonia

Mycoplasma pneumoniae

Chlamydia pneumoniae

Chylamydia trachomatis (newborns)

Legionella pneumophila


Name some risk factors for presence penicillin-resistant/drug-resistant pneumococci

Age > 65

beta-lactam use in last 3 months



multiple medical comorbidities

exposure to children at day care centers


Name some risk factors for presence of enteric gram negatives in CAP

Nursing home reisdent

cardiopulmonary disease

multiple medical comorbidities

recent Abx therapy


Name some modifying risk factors for pseudomonas in CAP

brochiectasis (think cystic fibrosis)

steroids >10 mg/day

BSA >7 days in past month



When organisms are identified in CAP, what organisms are most likely when...

  1. Outpatient without modifying risk factors or cardiopulmonary disease
  2. Outpatient with modifying risk factors or cardiopulmonary disease

  1. S. pneumoniae, M. pneumoniae, C. pneumoniae, H. influenza, viruses (also consider miscellaneous like Legionella, TB, and endemic fungi)
  2. Same as without modifying risk factors, plus DRSP, mixed (bacteria + atypical), enteric gram negatives, M. catarrhalis, and aspiration


What is the Abx treatment approach for...

  1. Outpatient without modifying risk factors or cardiopulmonary disease
  2. Outpatient with modifying risk factors or cardiopulmonary disease

  1. Advanced generation macrolide or doxycycline
  2. (Oral beta-lactam plus (macrolide or doxycycline)) OR antipneumococcal fluoroquinolone alone


What criteria system is used to prognosticate CAP mortality risk (and therefore, need to admit to the hospital)?

What are the elements of this rubric?



Urea (>19.1 mg/dL)

Respiratory Rate >30 br/min

Blood pressure <90mmHg systolic or <=60mmHg diastolic

Age >=65


CAP mortality is reduced if Abx are administered how quickly after presentation?

< 8 hours


What are (3) complicating factors that often decrease the utility of sputum analysis in CAP?

Why use it then?

30% of patients unable to produce a specimen

30% of patients treated with Abx prior to admission

25% of patients will have organisms that are difficult/slow to culture



Among hospitalized patients, what bugs (when found) are likely in:

  1. Hospitalized (non-ICU) without modifying risk factors or C-P disease?
  2. Hospitalized (non-ICU) with modifying risk factors or C-P disease?
  3. ICU-admitted without risk for pseudomonas?
  4. ICU-admitted with risk for pseudomonas?

  1. S. pneumoniae, H. influenza, M. pneumoniae, C. pneumoniae, mixed (bacteria + atypical), viruses, legionella, and miscellaneous (M. Tb, endemic fungi, PCP)
  2. Same as (1) plus DRSP, enteric gram negatives, aspiration
  3. S. pneumoniae and DRSP, legionella spp, H. influenza, enteric gram negative bacilli, S. aureus and MRSA, mycoplasma pneumoniae, viruses and miscellaneous (chlamydia, M. tuberculosis, endemic fungi)
  4. Same as (3) plus P. aeruginosa


What is the Abx treatment approach for:

  1. Hospitalized (non-ICU) without modifying risk factors or C-P disease?
  2. Hospitalized (non-ICU) with modifying risk factors or C-P disease?
  3. ICU-admitted without risk for pseudomonas?
  4. ICU-admitted with risk for pseudomonas?

  1. IV macrolide alone (or IV beta lactam plus doxycycline if intolerant) OR antipneumococcal fluoroquinolone alone
  2. (IV beta-lactam plus (macrolide or doxycycline)) OR antipneumococcal fluoroquinolone alone
  3. IV beta-lactam (cefoxatime, ceftriaxone) plus IV macrolide OR antipneumococcal fluoroquinolone alone. If MRSA or gram+ cocci in sputum, give vacomycin
  4. IV beta-lactam with antipseudomonal activity plus antipseudomonal fluoroquinolone OR IV beta-lactam with antipseudomonal activity plus IV aminoglycoside plus IV atypical coverage


In CAP, what is the approximate therapy response time after start of Abx for an uncomplicated, stable patient?

When does the fever typically resolve?

When does the WBC count typically resolve?

PEx findings?

Clearing of opacities on CXR?

up to 72 hours

2-4 days

4 days

>7 days in 20-40% of patients

50% @ 2wks; 67% @ 4wks; 75% @ 6wks


What is the typical course of oral Abx therapy (following transition from IV) in CAP?

What other criteria must be met before transition from IV to PO Abx?

7-14 days

Improvement of fever, cough/RD, leukocytosis, GI absorption


Describe Light's Criteria for exudative effusions

If any one of the following is true, the fluid is an exudate:

  • Pleural fluid LDH > 2/3 * (serum upper normal limit for LDH)
  • Pleural fluid LDH / serum fluid LDH > 0.6
  • Pleural fluid protein / serum fluid protein > 0.5


Describe the criteria for determining if a parapneumonic effusion should be drained with a chest tube

  • Criteria A
    • 0 - minimal (<10mm on lat decubitus XR)
    • 1 - moderate, free-flowing (>10mm on lateral decubitus and <1/2 hemithorax)
    • 2 - large free-flowing effusion (>1/2 hemithorax), loculated or thickened effusion on CT scan
  • Criteria B (bacteriology)
    • X - unknown
    • 0 - negative culture and gram stain
    • 1 - positive culture or gram stain
    • 2 - overt pus
  • Criteria C (pH)
    • X - unknown
    • 0 - >=7.20
    • 1 - <7.20

[A,B,C] = [0,X,X] or [1,0,0] -> no drainage

[A,B,C] = [2,1,1] or [X,2,X] -> yes drainage


What factors, affecting the chest wall, might lead to dyspnea?

Muscle weakness

Skeletal deformities (including trauma, scoliosis, etc)


What factors, affecting the pleural spaces, might cause dyspnea?

The lung parenchyma?

Pleural: Fluid, air, tumor

Parenchyma: Interstitial, alveolar


What is the mnemonic for differential diagnosis of dynspnea due to interstitial disease?


  • Sarcoidosis
  • Hypersensitivity pneumonitis
  • Idiopathic pulmonary fibrosis
  • Tuberculosis and tumor
  • Fungi
  • Asbestosis
  • Collagen vascular diseases
  • Eosinophilic granuloma
  • Drug-induced lung disease


What conditions are on the differential for dynspnea due to an airway problem?

Pulmonary arteries?



Airway: Bronchitis, emphysema, asthma, BOOP, upper airway obstruction

Arterial: PE, pulmonary HTN, pulmonary vasculitis

Neural: phrenic nerve dysfunction, quadraplegia (trauma -> SCI)

Pericardium: fluid-based or restrictive


What is the mnemonic for differential diagnosis of dyspnea due to alveolar disease?


  • Pus
  • Cells
  • Proteins
  • Inflammatory processes
  • Edema


What conditions affecting the heart might lead to dyspnea?

What about conditions affecting the blood?


Heart: Cardiomyopathy, diastolic dysfunction, ischemia, valvular origin, conduction abnormalities

Blood: anemia, altered hemoglobin states (smokers)

Psych: **diagnosis of exclusion** - hyperventilation syndrome or heightened response to stimuli (secondary to anxiety?)


Describe the Wells Clinical Prediction Model for diagnostic likelihood of of pulmonary embolism

Clincal variables and point values:

  • Signs and symptoms of DVT - 3.0
  • Alternative diagnosis is less likely than PE - 3.0
  • HR > 100 bpm - 1.5
  • Immobilization or surgery in past 4 weeks - 1.5
  • Previous VTE - 1.5
  • Hemoptysis - 1.0
  • Malignancy (or treatment for malignancy in last 6 months) - 1.0


  • low probability: <2 points
    • if D-dimer negative, stop
    • if D-dimer positive, go to imaging study
  • moderate probability: 2 to 6 points
  • high probability: >6 points

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