Pneumonia (Community-Acquired)
Evaluation
General—inflammation of the lungs is typically caused by an infectious process.
Clinical—cough, sputum production, shortness of breath, pleuritic chest pain, fatigue, and myalgias.
Etiology (in immunocompetent patients)
Typicals
Streptococcus pneumoniae (pneumococcus)—approximately 66% of bacterial pneumonias
Of note, prevalence of drug resistant S. pneumoniae is rising and may require intensive care unit (ICU) care.
Haemophilus influenzae
Atypicals (Mycoplasma and Chlamydia pneumoniae, Legionella)—approximately 20% to 40% of cases
Respiratory viruses (influenza, parainfluenza, adenovirus, respiratory syncytial virus [RSV], and coronavirus)
Anaerobes—typically found in aspiration pneumonia
Pseudomonas, Staphylococcus aureus, and gram-negative rods—typically need ICU care
Epidemiology—4 million cases of community-acquired pneumonia in the United States per year.
Risk factors—smoking is a risk factor for invasive pneumococcal disease.
Diagnostic algorithm
First, diagnose pneumonia based on history and physical and chest x-ray showing a pulmonary infiltrate.
Predictive rules (e.g.,—pneumonia severity index) help establish if hospitalization is needed.
Contraindications to outpatient treatment
Hypoxemia (O2 saturation <A onclick="get_content(event,'AB1-M12'); return false;" onmouseover="window.status=this.title; return true;" onmouseout="window.status=''; return true;" title="<90% or PaO2 <A onclick="get_content(event,'AB1-M12'); return false;" onmouseover="window.status=this.title; return true;" onmouseout="window.status=''; return true;" title="<60 mm Hg on room air)
Hemodynamic instability
Comorbid condition which mandates hospitalization or frail condition
Inability to take oral medications, or no response to oral medications
Unstable psychosocial situation
Factors, which increase risk from low (outpatient) to moderate-high (hospitalize)
Age older than 50
Comorbid condition (cancer, liver disease, renal disease, congestive heart failure [CHF], and so on)
Abnormalities on physical (altered mental status, vital sign abnormalities)
For further evaluation, obtain gram stain and cultures of blood and sputum
Treatment
