Pneumonia

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

1. See Also
   1. Viral Pneumonia
   2. Pneumonia in Children
   3. Pneumonia in the Elderly
   4. Pneumonia in the Nursing Home
2. 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
3. Epidemiology: Community acquired Pneumonia
   1. Adults: 346 Israeli patients admitted for Pneumonia
      1. Pneumococcal Pneumonia (43%)
      2. Mycoplasma pneumonia (29%)
      3. Chlamydia pneumoniae (18%)
      4. Legionella pneumonia (16%)
   2. References
      1. Lieberman (1996) Chest 109:1243-9
4. Causes: Community Acquired Pneumonia
   1. See Pneumonia Causes
   2. Bacteria: Typical
      1. Streptococcus Pneumoniae
      2. Staphylococcus aureus
      3. HaemophilusInfluenzae
      4. Moraxella catarrhalis
   3. Bacteria: Atypical
      1. Mycoplasma pneumoniae
      2. Legionella pneumonia
      3. Chlamydia Pneumonia
      4. Q Fever
      5. Psittacosis
   4. Virus
      1. Adenovirus
      2. Influenza A and B
      3. Parainfluenza
      4. Respiratory Syncytial Virus
   5. Fungus
      1. Blastomycosis
      2. Coccidioidomycosis
      3. Histoplasmosis
5. 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
6. 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
7. 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
   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
8. 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
9. Labs
   1. General
      1. Lab Indications
         1. Moderate or severe community acquired Pneumonia
         2. Patient with comorbid conditions
      2. Efficacy of Labs
         1. No value in non-severe community acquired Pneumonia
         2. Theerthakarai (2001) Chest 119:181-4
   2. Sputum Examination
      1. Tests
         1. Sputum Gram Stain
            1. Good quality sample: <25 epithelial cells/LPF and contains Neutrophils
         2. Sputum Culture
      2. Efficacy of Sputum exam
         1. IDSA/ATS recommends Sputum sample obtained for inpatients before antibiotic therapy
            1. Absence of Gram Negative Rods and Staphylococcus aureus on a good quality Sputum Culture is reassuring
            2. Sputum Culture can help direct subsequent antibiotic therapy narrowing
         2. Sputum has low diagnostic yield in Community acquired Pneumonia
            1. Not recommended in outpatient community acquired Pneumonia
            2. Ewig (2002) Chest 121:1486-92
   3. Blood Culture
      1. Indications
         1. Not indicated unless severe disease
         2. Recommended by ATS in hospitalized community acquired Pneumonia
         3. Highest yield in severe Pneumonia
      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
   4. Specific Testing with reasonable efficacy
      1. Chlamydia Pneumonia
         1. Rapid PCR (>30% Test Sensitivity)
      2. Influenza
         1. Rapid Influenza Test (Influenza DFA)
      3. Legionella pneumophila
         1. Rapid PCR of Sputum (80% Test Sensitivity)
         2. Urinary antigen (>50% Test Sensitivity)
      4. Mycoplasma pneumoniae
         1. Rapid PCR of Sputum (>30% Test Sensitivity)
   5. Thoracentesis with fluid analysis
      1. Indicated for Pleural Effusion >5 cm
      2. Send for Gram Stain, aerobic and anaerobic culture
10. Imaging: Chest XRay
    1. Indications: All cases of suspected CAP
       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. Ebell (2007) Am Fam Physician 76(4): 560-2
    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 CAP
    3. Interpretation
       1. Lobar infiltrate suggests typical bacterial CAP
       2. Diffuse, bilateral infiltrates suggests atypical CAP
11. Differential Diagnosis
    1. See Pneumonia Causes
    2. See Cough Causes
    3. Acute Respiratory Distress Syndrome
    4. Severe Acute Respiratory Syndrome
    5. Churg-Strauss Syndrome
    6. Congestive Heart Failure
    7. Inflammatory Lung Disease
    8. Idiopathic Pulmonary Fibrosis
    9. Interstitial pneumonitis
    10. Pulmonary Embolism
    11. Lung Cancer
    12. Sarcoidosis
    13. Wegener's Granulomatosis
    14. Bronchiolitis Obliterans with Organizing Pneumonia
    15. Bioterrorism Agents
        1. Anthrax
        2. Plague
        3. Tularemia
        4. Q Fever
        5. Brucellosis
12. Management
    1. See Pneumonia Management
    2. See Community Acquired Pneumonia Refractory to Standard Management
    3. Convert to oral antibiotic within 72 hours if possible
    4. See Pneumonia Hospitalization Criteria
    5. See Pneumonia Hospitalization Criteria in the Elderly
    6. See Severe Community Acquired Pneumonia Criteria
    7. See Mortality Prediction Tool for Patients with Community Acquired Pneumonia (CURB-65)
    8. See Pneumonia IRVS Prediction Tool (SMART-COP)
13. Complications
    1. Pulmonary
       1. Parapneumonic Effusion or empyema
       2. Pneumothorax
       3. Lung Abscess
       4. Bronchopleural Fistula
       5. Necrotizing Pneumonia
       6. Acute Respiratory Failure
    2. Metastatic spread
       1. Meningitis or CNS abscess
       2. Pericarditis or endocarditis
       3. Osteomyelitis or Septic Arthritis
    3. Systemic
       1. Sepsis or SIRS
       2. Hemolytic Uremic Syndrome
    4. References
       1. Bradley (2011) Clin Infect Dis 53(7): e1-52
14. Prognosis: Predictors of increased mortality
    1. See Pneumonia Prognostic Factors in Older Patients
    2. See Mortality Prediction Tool for Patients with Community Acquired Pneumonia (CURB-65)
    3. Comorbid neurologic disease
    4. Renal disease
    5. Congestive Heart Failure
    6. Hypotension
    7. Tachypnea
    8. Hypothermia
    9. Hypoglycemia (Serum Glucose <70mg/dl on presentation)
15. Prevention
    1. See Pneumonia Prevention in the Elderly
    2. See Influenza Vaccine
    3. See Pneumococcal Vaccine
16. Resources
    1. Pneumonia Severity Index
       1. http://www.aafp.org/afp/20030815/tips/6.html
17. References
    1. Bernstein (1999) Chest 115:9S-13S
    2. Cunha (2001) Med Clin North Am 85(1):43-77
    3. Fine (1997) N Engl J Med 336:243-50
    4. Fine (1990) Am J Med 89:713-21
    5. Gleason (1997) JAMA 278:32-9
    6. Lim (2009) Thorax 64(suppl 3):1-55
    7. Lutfiyya (2006) Am Fam Physician 73:442-50
    8. Marrie (2000) Clin Infect Dis 31(4):1066-78
    9. Metlay (2003) Ann Intern Med 138:109-18
    10. Watkins (2011) Am Fam Physician 83(11): 1299-306