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Classifications of Pneumonia

• Community-Acquired (CAP)
• Healthcare-Associated (HAP)
  • Any IV therapy, wound care, or chemotherapy within 20 days
  • Resident of nursing home or other long term care facility
  • Hospitalization for ≥ 2 days within 90 days
  • Visit to outpatient clinic or hemodialysis within 30 days
• Ventilator-Associated (VAP)
  • Currently or previously intubated during current hospitalization

Epidemiology

• 6 cases per 1000 persons per year (~ 5 million cases per year)
• Top 10 in mortality in US (~60,000 deaths/year)
• 12% 30-day mortality in patients requiring admission
• 28% all-cause mortality within one year

 

Pathogenesis

4 phases of development

• Edema
  • Proteinaceous exudate in the alveoli
  • Bacteria accumulation
• Red hepatization
  • Erythrocyte extravasation
• Grey hepatization
  • Neutrophil extravasation with bacterial clearance
• Resolution
  • Macrophage proliferation with inflammatory response

 

Risk Factors

• Age
• Winter months
• Increased risk of aspiration (AMS, CVA, intoxication, seizures)
• Smoking
• Underlying pulmonary disease (Asthma, COPD, cancer)
• Immunosupression
• Viral URI
• Decreased host defenses (impaired ciliary clearance)
• Acid-reducing medications
• Malnutrition
• Inhalation exposures

 

Pathogens

• Viral (most common)
  • Rhinovirus (most common)
  • Influenza
  • Adenovirus
  • Respiratory Syncytial Virus (RSV)
• Bacterial
  • S. pneumoniae (most common CAP)
  • H. influenza
  • M. pneumoniae (most common atypical)
  • K. pneumoniae (tends to be more severe)
  • Legionella
  • ESKAPE bugs (>80% of VAP)
    • Enterococcus
    • Staphylococcus
    • Klebsiella
    • Acinetobacter
    • Pseudomonas
    • Enterobacter
• Fungal (immunocompromised)
  • Histoplasmosis
  • Cryptococcus
  • Coccidioides
  • Blastomycosis
  • Aspergillus

Signs and Symptoms

• Productive cough
• Fever
• Chills and/or rigors
• Dyspnea
• Pleuritic chest pain
• Nausea/vomiting
• Altered mental status

 

Physical Exam Findings

• Vital signs
  • Febrile (elderly may not mount a response)
  • Tachycardic
  • Tachypnic
• Pulmonary
  • Rales and/or rhonchi
  • Signs of consolidation
    • Decreased breath sounds
    • Dullness to percussion
    • Increased tactile fremitus
    • Egophany
    • Whispered pectoriliquoy

 

Radiographic Evaluation

• Bacterial
  • Unilateral, lobar, air bronchograms

• Viral
  • Diffuse or perihilar, bilateral

Laboratory Evaluation

• CBC with differential
• Blood cultures
• Sputum culture and gram stain
  • Good sample = PMNs with < 10 squamous cells per LPF
• Urine antigen (pneumococcal and Legionella)
• Multiplex PCR

Should They Stay or Should They Go Now????

• Pneumonia Severity Index (PSI)
  • Step 1
    • If none of the following, then Class I and outpatient treatment
      • Age > 50 years
      • Neoplastic disease
      • Heart failure
      • Cerebrovascular disease
      • Renal disease
      • Liver disease
      • Altered mental status
      • HR ≥ 125/min
      • RR ≥ 30/min
      • SBP ≤ 90 mmHg
      • Temperature ≤ 35^oC or ≥ 40^oC
  • Step II

• CURB-65 Score
  • 5 variables
    • Confusion
    • Urea (BUN ≥ 20 mg/dL)
    • Respiratory rate ≥ 30/min
    • Blood pressure (SBP < 90 mmHg or DBP < 60 mmHg)
    • Age ≥ 65 years
  • Interpretation
    • Score 0-1 = Outpatient management
    • Score 2-3 = Inpatient management
    • Score 4-5 = ICU management
• SMART-COP Score
  • Used to predict need for respiratory or vasopressor support

 

Treatment

• Care should be taken to think about patients with risk factors for drug-resistant S. pneumoniae:
  • Age > 65 years
  • Beta-lactam, macrolide, or fluouroquinolone in the past 3-6 months
  • Alcoholism
  • Medical comorbidities
  • Immunosuppression
  • Exposure to child in daycare
• Community-Acquired

• Healthcare-Associated

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Cottage Physician

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References

1. Mandell LA, Wunderink RG. Pneumonia. In: Kasper D, Fauci A, Hauser S, Longo D, Jameson J, Loscalzo J. eds. Harrison’s Principles of Internal Medicine, 19e. New York, NY: McGraw-Hill; 2015. http://accessmedicine.mhmedical.com/content.aspx?bookid=1130&Sectionid=79733578. Accessed July 11, 2016.
2. Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia. American journal of respiratory and critical care medicine. 171(4):388-416. 2005. [pubmed]
3. File TM, Marrie TJ. Burden of community-acquired pneumonia in North American adults. Postgraduate medicine. 122(2):130-41. 2010. [pubmed]
4. Murthy SV. Pathology of Pneumonia.    http://www.slideshare.net/vmshashi/pathology-of-pneumonia.  Accessed on July 11,  2016.
5. Almirall J, Bolíbar I, Balanzó X, González CA. Risk factors for community-acquired pneumonia in adults: a population-based case-control study. The European respiratory journal. 13(2):349-55. 1999. [pubmed]
6. Mandell LA, Wunderink RG, Anzueto A. Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 44 Suppl 2:S27-72. 2007. [pubmed]
7. Musher DM, Thorner AR. Community-acquired pneumonia. The New England journal of medicine. 371(17):1619-28. 2014. [pubmed]
8. Jain S, Self WH, Wunderink RG. Community-Acquired Pneumonia Requiring Hospitalization among U.S. Adults. The New England journal of medicine. 373(5):415-27. 2015. [pubmed]
9. Metlay JP, Kapoor WN, Fine MJ. Does this patient have community-acquired pneumonia? Diagnosing pneumonia by history and physical examination. JAMA. 278(17):1440-5. 1997. [pubmed]
10. Fine MJ, Auble TE, Yealy DM. A prediction rule to identify low-risk patients with community-acquired pneumonia. The New England journal of medicine. 336(4):243-50. 1997. [pubmed]
11. Lim WS, van der Eerden MM, Laing R. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study. Thorax. 58(5):377-82. 2003. [pubmed]
12. Charles PG, Wolfe R, Whitby M. SMART-COP: a tool for predicting the need for intensive respiratory or vasopressor support in community-acquired pneumonia. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 47(3):375-84. 2008. [pubmed]
13. Pugh R, Grant C, Cooke RP, Dempsey G. Short-course versus prolonged-course antibiotic therapy for hospital-acquired pneumonia in critically ill adults. The Cochrane database of systematic reviews. 2015. [pubmed]