Community Acquired Pneumonia Exam
Questions And Answers Graded A+
Epidemiology
Community-Acquired Pneumonia
• An estimated 5.6 million cases/year
• Estimated total annual cost is $10 billion
• 6th leading cause of death in U.S.
- #1 cause of death from infectious diseases
• Up to 80% of treatment is outpatient
• Mortality rate varies
- <1-5% outpatient
- 12% inpatient
- Up to 40% in critically ill/ICU admissions
Pathogenesis
Community-Acquired Pneumonia
• Microorganisms gain access to the lower
respiratory tract via:
- Inhaled as aerosolized particles
- Enter via bloodstream from an extra-pulmonary site of infection
- Aspiration of oropharyngeal contents
- Commensal bacteria in respiratory tract
become pathogenic
• When pulmonary defenses are functioning optimally, aspirated organisms are cleared via the
mucociliary
transport system, coughing, and alveolar macrophages
• Factors that promote aspiration include altered MS (stroke, seizure), neuromuscular dz, ETOH and
medications
• Lung infections w/viruses can suppress antibacterial activity of the lungs by impairing alveolar
macrophage
fxn and mucociliary clearance
• Mucociliary clearance is reduced by diseases, ETOH, and drugs (narcotics)
• Defects in cellular and humoral immune function
Etiology
Community-Acquired Pneumonia
• The causative organism is only identified in 30- 50% of cases of CAP
• S. pneumoniaeis most common cause
• Underlying lung disease (i.e. COPD)
-H. influenzae, Moraxella catarrhalis
• s/p respiratory viral infxn (i.e. influenza)
-S. aureus
• Chronic oral steroids/severe underlying
bronchopulm dz, ETOH, frequent abx use
- Enterobacteriaceae, P. aeruginosa
Factors that Increase Risk with
Specific Pathogens
, Community-Acquired Pneumonia
• Penicillin-resistant/drug resistant pneumococci
- Age < 2 or > 65, ß-lactam tx (or other antimicrobials) w/in past 3 mos, ETOH, immunosuppression,
multiple
medical comorbidities, exposure to a child in daycare
• Enteric gram-negatives
- Underlying cardiopulmonary dz, multiple medical comorbidities, recent antibiotic tx, ETOH
•Pseudomonas aeruginosa
- Structural lung dz, corticosteroid tx, broad spectrum antibiotic tx for >7 days in past month,
malnutrition
Mechanisms of Resistance
Community-Acquired Pneumonia
S. pneumoniae
-altered pen binding protein
H. influenzae
-Beta-lactamase
M. catarrhalis
-Beta-lactamase
CAP Presentation
Community-Acquired Pneumonia
• Signs/symptoms
• Physical examination
• Chest x-ray
• Laboratory tests
Signs/Symptoms
Community-Acquired Pneumonia
• Abrupt onset of:
- Fever
- Chills
- Dyspnea
- Cough
• Productive vs nonproductive
- Chest pain
- Mental status changes
- Fatigue
- Headache
• Atypical pathogen
presentation may be
more sub-acute
- Onset may be more
gradual
Physical Examination
Community-Acquired Pneumonia
• Tachypnea, tachycardia
• Lung examination
- Dullness to percussion
- Diminished breath sounds
- Inspiratory crackles
Questions And Answers Graded A+
Epidemiology
Community-Acquired Pneumonia
• An estimated 5.6 million cases/year
• Estimated total annual cost is $10 billion
• 6th leading cause of death in U.S.
- #1 cause of death from infectious diseases
• Up to 80% of treatment is outpatient
• Mortality rate varies
- <1-5% outpatient
- 12% inpatient
- Up to 40% in critically ill/ICU admissions
Pathogenesis
Community-Acquired Pneumonia
• Microorganisms gain access to the lower
respiratory tract via:
- Inhaled as aerosolized particles
- Enter via bloodstream from an extra-pulmonary site of infection
- Aspiration of oropharyngeal contents
- Commensal bacteria in respiratory tract
become pathogenic
• When pulmonary defenses are functioning optimally, aspirated organisms are cleared via the
mucociliary
transport system, coughing, and alveolar macrophages
• Factors that promote aspiration include altered MS (stroke, seizure), neuromuscular dz, ETOH and
medications
• Lung infections w/viruses can suppress antibacterial activity of the lungs by impairing alveolar
macrophage
fxn and mucociliary clearance
• Mucociliary clearance is reduced by diseases, ETOH, and drugs (narcotics)
• Defects in cellular and humoral immune function
Etiology
Community-Acquired Pneumonia
• The causative organism is only identified in 30- 50% of cases of CAP
• S. pneumoniaeis most common cause
• Underlying lung disease (i.e. COPD)
-H. influenzae, Moraxella catarrhalis
• s/p respiratory viral infxn (i.e. influenza)
-S. aureus
• Chronic oral steroids/severe underlying
bronchopulm dz, ETOH, frequent abx use
- Enterobacteriaceae, P. aeruginosa
Factors that Increase Risk with
Specific Pathogens
, Community-Acquired Pneumonia
• Penicillin-resistant/drug resistant pneumococci
- Age < 2 or > 65, ß-lactam tx (or other antimicrobials) w/in past 3 mos, ETOH, immunosuppression,
multiple
medical comorbidities, exposure to a child in daycare
• Enteric gram-negatives
- Underlying cardiopulmonary dz, multiple medical comorbidities, recent antibiotic tx, ETOH
•Pseudomonas aeruginosa
- Structural lung dz, corticosteroid tx, broad spectrum antibiotic tx for >7 days in past month,
malnutrition
Mechanisms of Resistance
Community-Acquired Pneumonia
S. pneumoniae
-altered pen binding protein
H. influenzae
-Beta-lactamase
M. catarrhalis
-Beta-lactamase
CAP Presentation
Community-Acquired Pneumonia
• Signs/symptoms
• Physical examination
• Chest x-ray
• Laboratory tests
Signs/Symptoms
Community-Acquired Pneumonia
• Abrupt onset of:
- Fever
- Chills
- Dyspnea
- Cough
• Productive vs nonproductive
- Chest pain
- Mental status changes
- Fatigue
- Headache
• Atypical pathogen
presentation may be
more sub-acute
- Onset may be more
gradual
Physical Examination
Community-Acquired Pneumonia
• Tachypnea, tachycardia
• Lung examination
- Dullness to percussion
- Diminished breath sounds
- Inspiratory crackles
