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Pneumonia

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Pneumonia, Bacterial Pneumonia, Atypical Pneumonia, Community-Acquired Pneumonia, CAP

  • Definition
  • Community Acquired Pneumonia (CAP)
  1. Lower respiratory tract infection
  2. Develops in non-hospitalized patient
  3. May be Bacterial, viral, fungal or parasitic
  4. May be present despite normal Chest XRay
  • Epidemiology
  • Community acquired Pneumonia
  1. Incidence: 9.2 to 33 per 1000 person-years in U.S.
  2. Adult mortality: 60,000 deaths per year from Pneumonia or Influenza (8th leading cause of death)
  3. Most severe cases in very young and very old
  4. U.S. cost/year for community acquired Pneumonia: $10-17 billion (90% of cost is inpatient care)
  • Risk Factors
  1. Age over 65 years
  2. Recent antibiotics
  3. Immune compromised (e.g. HIV Infection)
  4. Respiratory illness (COPD, Asthma)
  5. Vascular disease (CHF, CVA)
  6. Diabetes Mellitus
  7. Chronic Liver Disease
  8. Chronic Kidney Disease
  9. Cancer
  • Findings
  • Signs and Symptoms
  1. Bacterial Pneumonia
    1. Cough
      1. Productive of Purulent Sputum with typical Bacteria
      2. Non-productive in atypical cases
    2. Sudden onset
    3. Fever and Chills
    4. Fatigue
    5. Ill appearing patient
    6. Pleuritic Chest Pain
    7. Dyspnea
    8. Tachypnea
    9. Tachycardia
  2. Viral Pneumonia
    1. Non-productive cough
    2. Gradual Onset with prodrome (malaise and Headache)
    3. Chest XRay more impressive than exam
    4. Onset in fall or winter
    5. Wheezing more common in viral causes
    6. Low grade Temperature (<101.3 F)
  3. Mycoplasma pneumonia
    1. Constant, harsh, non-productive cough
    2. Wheezing may occur in Mycoplasma pneumonia
    3. Fever typically lasts longer than 3 days
    4. More common in age over 3 years
  4. Legionella
    1. Onset with myalgias and Headache
    2. Fever to 104 F for first few days
    3. Gastrointestinal symptoms predominate in up to 40%
    4. Cough is late onset, mild, often non-productive
  • Signs
  1. General findings
    1. Fever
      1. Positive Likelihood Ratio: 2.1
      2. Negative Likelihood Ratio: 0.71
    2. Ill appearing patient
    3. Dyspnea
    4. Tachypnea
    5. Tachycardia
    6. Hypoxia (check Oxygen Saturation)
  2. Localized findings at involved lung region
    1. Egophony
      1. Positive Likelihood Ratio: 8.6
      2. Negative Likelihood Ratio: 0.96
    2. Dullness to percussion
      1. Positive Likelihood Ratio: 4.3
      2. Negative Likelihood Ratio: 0.79
    3. Rales
    4. Diminished breath sounds
    5. Bronchial breath sounds
    6. Tactile fremitus
  3. References
    1. Metlay (1997) JAMA 278(17): 1440-5 [PubMed]
  • Diagnosis
  1. See Diehr Rule to Diagnose Pneumonia
  2. Findings with highest Test Sensitivity for Pneumonia
    1. Fever and chills
    2. Pleuritic Chest Pain
    3. Cough productive of mucopurulent Sputum
    4. Dyspnea
    5. Tachypnea (especially in over age 65 years)
  3. Findings with highest Specificity
    1. Asymmetric breath sounds
    2. Pleural rubs
    3. Egophony
    4. Increased tactile fremitus
  • Labs
  1. General
    1. Consider specific testing based on risks
      1. See Pneumonia Causes (as well as indications below)
    2. Lab Indications
      1. Moderate or severe community acquired Pneumonia
      2. Patient with comorbid conditions
    3. Efficacy of Labs
      1. No value in non-severe community acquired Pneumonia
      2. Theerthakarai (2001) Chest 119:181-4 [PubMed]
  2. Sputum Gram Stain and Culture
    1. See Sputum Culture
    2. Adequacy
      1. Good quality sample: <25 epithelial cells/LPF and contains Neutrophils
    3. Indications (IDSA/ATA 2007)
      1. ICU Admission (consider endotracheal aspirate if intubated)
      2. Failed outpatient antibiotic therapy
      3. Cavitary infiltrates (obtain specific fungal and Tuberculosis cultures)
      4. Active Alcohol Abuse
      5. Severe COPD
      6. Pleural Effusion (also perform Thoracentesis for Pleural Fluid culture and analysis)
      7. Positive Legionella urine antigen (Legionella culture requires special media)
      8. Positive Pneumococcal urine antigen
    4. Efficacy
      1. Sputum has low diagnostic yield in Community acquired Pneumonia
        1. Not recommended in outpatient community acquired Pneumonia
        2. Ewig (2002) Chest 121:1486-92 [PubMed]
  3. Blood Culture
    1. Indications (IDSA/ATA 2007)
      1. Not indicated unless severe disease (highest yield in severe Pneumonia)
      2. Consider in hospitalized community acquired Pneumonia (especially if possible ICU patient)
      3. Intensive care unit admission
      4. Cavitary infiltrates
      5. Leukopenia
      6. Active Alcohol Abuse
      7. Chronic severe liver disease
      8. Asplenia
      9. Pleural Effusion
      10. Positive Pneumococcal urine antigen
    2. Efficacy
      1. Low sensitivity: Positive in only 5-10% of cases
      2. Does not predict severity or outcome
    3. References
      1. Campbell (2003) Chest 123:1142-50 [PubMed]
  4. Specific Testing with reasonable efficacy
    1. Influenza
      1. Rapid Influenza Test (Influenza DFA)
    2. Legionella pneumophila
      1. Rapid PCR of Sputum (80% Test Sensitivity)
      2. Urinary antigen
        1. Test Sensitivity 70-90% (for serogroup 1, responsible for >80% of cases)
        2. Test Specificity 99%
      3. Indications (Legionella UAT per IDSA/ATS 2007)
        1. Intensive care unit admission
        2. Failed outpatient antibiotic therapy
        3. Active Alcohol Abuse
        4. Travel within prior 2 weeks
        5. Pleural Effusion
    3. Mycoplasma pneumoniae
      1. Rapid PCR of Sputum (>30% Test Sensitivity)
    4. Chlamydia Pneumonia
      1. Rapid PCR (>30% Test Sensitivity)
    5. Streptococcus Pneumoniae (Pneumococcus)
      1. Pneumococcal Urine antigen Test (UAT)
        1. Test Sensitivity 60-80%
        2. Test Specificity >90%
      2. Indications (Pneumococcal UAT per IDSA/ATS 2007)
        1. Intensive care unit admission
        2. Failed outpatient antibiotic therapy
        3. Active Alcohol Abuse
        4. Chronic severe liver disease
        5. Leukopenia
        6. Asplenia
        7. Pleural Effusion
  5. Thoracentesis with fluid analysis
    1. Indicated for Pleural Effusion >5 cm
    2. Send for Gram Stain, aerobic and anaerobic culture
  6. Fungal and TB Culture
    1. Cavitary lesions
    2. Foreign travel or immigration
  7. References
    1. Mandell (2007) Clin Infect Dis 44:S27–72 [PubMed]
  1. Indications: All cases of suspected Community Acquired Pneumonia
    1. Any patient with at least 1 of the following
      1. Temperature >100 F (37.8 C)
      2. Heart Rate >100 beats/min
      3. Respiratory Rate >20 breaths/min
    2. Any patient with at least 2 of the following
      1. Decreased breath sounds
      2. Rales or crackles
      3. No Asthma history to explain findings
    3. Other indications (not included in Ebell protocol)
      1. Hypoxemia
      2. Confusion
      3. Known structural lung disease
      4. Age > 60 years old
      5. Systemic illness signs
    4. Ebell (2007) Am Fam Physician 76(4): 560-2 [PubMed]
  2. Precautions: False negatives in early presentation
    1. Serial Chest XRays may be needed
    2. Does not exclude Pneumonia in severe illness
      1. Positive in only 40% of acute pneumococcal community acquired Pneumonia (CAP)
  3. Precautions: Underlying malignancy
    1. Confirm infiltrate resolution at 6 weeks after management (especially in smokers, or those over age 50)
  4. Interpretation
    1. Lobar infiltrate suggests typical Bacterial community acquired Pneumonia (CAP)
    2. Diffuse, bilateral infiltrates suggests atypical community acquired Pneumonia (CAP)
  1. May be more accurate than Chest XRay in the diagnosis of Pneumonia
  2. Also defines other respiratory conditions at the bedside (e.g. Pneumothorax, Pleural Effusion)
  3. Test Sensitivity: 94 to 95%
  4. Test Specificity: 90 to 96%
  5. Chavez (2014) Respir Res 15:50 [PubMed]
  6. Ye (2015) PLoS One 10(6): e0130066 [PubMed]