Pneumonia

PNEUMONIA Overview

  • Pneumonia is a severe infection affecting the lungs, leading to inflammation and fluid accumulation in the alveoli.

  • It remains one of the leading causes of death from infectious diseases, particularly in older adults.

  • Can be categorized into two main types: community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP).

Statistics

  • Commonality: Leading cause of death from infectious disease in the U.S.

  • Hospital-Acquired Pneumonia (HAP):

    • Second most prevalent nosocomial infection, affecting 0.6%–1.1% of hospitalized patients.

    • Highest incidence in ICU patients post thoracic or abdominal surgery and elderly patients.

  • Mortality Rates:

    • Community-acquired pneumonia without hospitalization: <1%

    • Community-acquired pneumonia with hospitalization: ~14%

    • Ventilator-associated pneumonia (VAP): 20%–50%

Community-Acquired Pneumonia (CAP)

  • Defined as an acute infection of the pulmonary parenchyma accompanied by radiological or auscultatory evidence.

  • Exclusion Criteria: Must not have certain characteristics prior to diagnosis:

    • Hospitalization for 2 days or more in the previous 90 days

    • Residence in long-term care facilities

    • Receipt of intravenous antibiotics, chemotherapy, or wound care in the last 30 days

    • Attendance at a hospital clinic or hemodialysis within 30 days.

Symptoms of Pneumonia

  • Common Symptoms:

    • Fever or hypothermia

    • Rigors

    • Sweats

    • New cough (90%), with or without sputum

    • Chest discomfort (50%)

    • Onset of dyspnea (66%)

    • General exhaustion, myalgias, abdominal pain, anorexia, headache

  • Note on Older Adults: Symptoms may be fewer or less severe, with common mental status changes.

Predictors of Severe Pneumonia

  • Factors that increase the risk of serious outcomes:

    • Age > 65 years

    • Comorbid conditions (diabetes, heart failure, chronic lung/liver disease, renal failure)

    • High temperature (> 101°F / 38°C)

    • Presence of bacteremia

    • Altered mental status

    • Immunosuppression (steroids, cancer)

    • High-risk pathogens (e.g., Staphylococcus aureus, Legionella)

    • Multilobe pneumonia or pleural effusions

  • Hospitalization should be guided by severity scales like CURB-65.

CURB-65 Severity Assessment

  • Points allocation:

    • Confusion: 1 point

    • Urea > 19 mg/dL: 1 point

    • Respiratory rate > 30 breaths/min: 1 point

    • SBP < 90 mm Hg / DBP < 60 mm Hg: 1 point

    • Age > 65 years: 1 point

  • Treatment Location Based on Score:

    • 0-1: Treat as outpatient (death risk: 0.7-2.1%)

    • 2: Outpatient or inpatient (risk: 9.2%)

    • 3: Inpatient (ICU risk: 14.5%)

    • 4-5: Inpatient (ICU risk: 40% and 57% respectively)

Hospital Acquired Pneumonia (HAP) and Ventilator-Assisted Pneumonia (VAP)

  • HAP: Develops 48 hours post-admission, not incubating upon arrival.

  • VAP: Arises more than 48 hours after intubation.

  • Health Care-Associated Pneumonia (HCAP): Occurs after significant health care contact; not included in 2016 HAP/VAP guidelines.

  • Important to assess for multidrug-resistant (MDR) organisms in these cases.

Risk Factors for HAP/VAP

  • Elevated risk due to several factors:

    • Intubation and mechanical ventilation

    • Supine positioning of patients

    • Enteral feeding practices

    • Oropharyngeal colonization

    • Stress bleeding prophylaxis

    • Blood transfusions

    • Hyperglycemia

    • Immunosuppression or corticosteroid use

    • Recent surgical procedures (thoracoabdominal, etc.)

    • Patient immobilization or use of nasogastric tubes

    • Recent antibiotic therapy

    • ICU admission

    • Older age

    • Pre-existing chronic lung conditions

Epidemiology and Bacterial Causes

  • Common Causes of CAP:

    • 40-60% unidentifiable causes

    • Mycoplasma pneumoniae: 13-37%

    • Streptococcus pneumoniae: 9-20%

  • Common Causes of HAP:

    • Unidentifiable: 50%

    • S. aureus: 10%

    • Pseudomonas aeruginosa, Klebsiella pneumoniae, etc.

Clinical Considerations in Specific Populations

  • Alcoholism: Increased risk for S. pneumoniae, oral anaerobes

  • Nursing Home Residents: Higher incidences of S. pneumoniae, H. influenzae

  • COPD Patients: Frequently associated with S. pneumoniae, H. influenzae

  • Post-Influenza: Recurrence of H. influenzae, S. pneumoniae

  • Exposure to Water: Risks of Legionella exposure

  • Poor Oral Hygiene: Linked to oral anaerobes

  • HIV Infection: Higher incidence of Pneumocystis jirovecii and other pathogens

By understanding the symptoms, risks, and treatments associated with pneumonia, healthcare professionals can better manage this widespread infection.