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
  • 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 develops >48 hours after endotracheal intubation
  • Health care–associated pneumonia (HCAP): This categorization is no longer used.

Epidemiology

• In the United States as of 2018, CAP is the eighth most common cause of death (even higher in those >65) and most common cause of death related to infection.
• Pneumonia causes 3.2 million estimated deaths.
• 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 informs 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
  • <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-α 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 PPSV23 only. Adults >65 years old in the high risk group should receive PCV13 followed by pneumococcal polysaccharide (PPSV23) ≥1 year interval.
• For adults ≥65 years old in the high risk group 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 who were previously given PPSV23 should receive a PCV13 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