Description

Bacterial pneumonia can be classified as the following:

• Community-acquired pneumonia (CAP): acute infection of the pulmonary parenchyma acquired outside of a health care setting or long-term care facility
• Nosocomial pneumonia: acute infection of the pulmonary parenchyma acquired in health care settings
  • Health care associated pneumonia (HCAP): occurs in a nonhospitalized patient with extensive health care contact, such as:
    • Residing in a long-term care facility
    • Hospitalization in an acute care hospital for ≥2 days within the past 90 days
    • Hemodialysis clinic within the past 30 days
  • Hospital-acquired pneumonia (HAP): occurs ≥48 hours after admission and did not appear to be incubating at time of admission
  • Ventilator-associated pneumonia (VAP): pneumonia that develops >48 hours after endotracheal intubation

Epidemiology

• In the United States as of 2017, community acquired pneumonia is the ninth most common cause of death (even higher in those older than 65 years) and most common cause of death related to infection
• Pneumonia causes 3.2 million estimated deaths globally
• HAP is the leading cause of death among nosocomial infections and is one of the leading causes of death in the ICU.
• Rates of infection are 3 times higher in African Americans than in whites and are 5 to 10 times higher in Native American adults and 10 times higher in Native American children.
• Mortality rate in children is approximately 1.6 million a year. Hospitalization rate for children with CAP is still highest among the very young ages (<18 months). Respiratory viruses are the most commonly detected causes of pneumonia in children (1).

• CAP: 5 to 6 cases per 1,000 persons with increased incidence occurring in the winter months
• HAP: 5 to 20 cases per 1,000 admissions; incidence increases 6- to 20-fold in ventilated patients

Etiology and Pathophysiology

• Pathogenicity of the implicated organisms inform the presentation and antibiotic choice
• Adults, CAP
  • Typical (85%): Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, group A Streptococcus, Moraxella catarrhalis
  • Atypical (15%): Legionella sp., Mycoplasma pneumoniae, Chlamydophila pneumoniae
• Adults, HCAP/HAP/VAP
  • Aerobic gram-negative bacilli: Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Acinetobacter sp.
  • Gram-positive cocci: Streptococcus sp. and S. aureus (including MRSA)
• Pediatric
  • Birth to 3 weeks: E. coli, group B Streptococci, Listeria monocytogenes
  • Less than 3 months: Chlamydia trachomatis, S. pneumoniae, H. influenzae
  • 3 months to 18 years
    • Typical: S. pneumoniae
    • Atypical: C. pneumoniae, M. pneumoniae

Risk Factors

• Immunosuppression:
  • Chronic steroid use (>20 mg/day or >2 mg/kg/day of prednisone for >14 days)
  • HIV/immunoglobulin deficiencies/solid organ transplant/TNF-alpha inhibitor therapy
• Chronic health conditions
  • Asthma, COPD
  • Type 2 DM, chronic renal failure, CHF, liver disease, tobacco use
• Other:
  • Age >65 years
  • Antibiotic therapy in the past 6 months/resistance to antibiotics
  • Hospitalization for ≥2 days during past 90 days
  • Poor functional status as defined by activities of daily living score

General Prevention

Vaccination recommendations:

• All children 2 to 59 months of age should be routinely vaccinated with pneumococcal conjugate (PCV13); given at 2, 4, and 6 months of age; a fourth dose at 12 to 15 months of age
• Adults ≥65 years who are vaccine naïve should receive PCV13 followed by pneumococcal polysaccharide (PPSV23) ≥1 year interval.
• For adults ≥65 years old who have already received PPSV23, a dose of PCV13 is indicated after ≥1 year.
• Adults 19 to 64 years with tobacco use, chronic heart or lung disease, alcoholism, or chronic liver disease should receive a dose of PPSV23, followed by PCV13 at age 65 and a subsequent PPSV23 ≥1 year after PCV13 and at least 5 years after the previous PPSV23 dose.
• High-risk adults ≥19 years old with immunocompromising conditions: asplenia, CSF leaks, cochlear implants, HIV infection, immunodeficiencies: 1 dose of PCV13 followed by PPSV23 after ≥8 weeks. A second dose of PPSV23 is recommended for all except those with CSF leak or cochlear implant; it should be given 5 years after first dose. A final dose of PPSV23 should be administered at age 65 and at least 5 years after the previous dose. Those they were previously given PPSV23 should receive a PPCV13 dose ≥1 year after last PPSV23. If additional PPSV23 is required, it should be given ≥8 weeks after PCV13 and 5 years after most recent dose of PPSV23.
• Annual influenza vaccine