Community-Acquired Pneumonia (CAP)

• Pneumonia involves infection in one or both lungs.
• Parenchyma, alveolar spaces, and/or interstitial tissue can be affected.

Etiology

• Pneumonia categorization depends upon where it was acquired.
• Community Acquired Pneumonia (CAP) refers to acute infection of the pulmonary parenchyma outside a health care setting.
• Nosocomial pneumonia involves acute infection of the pulmonary parenchyma acquired in the hospital, including hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP).

Etiology in Adults with CAP

• Viruses, including influenza, are causal agents.
• Bacteria are the most common cause, which can be either typical or atypical organisms.
• Common outpatient CAP causes include S. pneumoniae, M. pneumoniae, H. influenzae, S. aureus, Legionella, and respiratory viruses.

Organisms in Community-Acquired Pneumonia (CAP)

• Typical organisms include Streptococcus pneumoniae (accounting for 60% to 70% of bacterial CAP cases), Hemophilus influenzae, S. aureus, Moraxella catarrhalis, anaerobes, and aerobic gram-negative bacteria.
• Atypical organisms include Legionella, Mycoplasma pneumoniae, Chlamydia pneumoniae, Chlamydia psittaci, and respiratory viruses.

Epidemiology

• CAP is a common and morbid condition in U.S. clinical practice.
• Annually, 5-10 million U.S. residents contract CAP.
• Each year, 1 million U.S. adults are hospitalized due to Pneumonia, and 50,000 die.

Risk Factors

• Older age, specifically, >/ 65 years old, affects approximately 2000 per 100,000 in the U.S.
• Chronic diseases like diabetes, renal disease, COPD, CAD, and CHF increase risk.
• Viral respiratory tract infections are another risk factor.
• Smoking and alcohol overuse are also risk factors.

Classic Presentation

• Cough, which may or may not produce sputum, is a common symptom.
• Dyspnea is another typical symptom.
• Pleuritic chest pain can occur.
• Physical exam findings include tachypnea, increased work of breathing, adventitious breath sounds (rales/crackles, rhonchi), tactile fremitus, egophony, and dullness to percussion as well as Fever>100.4 F.

Differential Diagnosis

• Noninfectious illnesses that mimic CAP include CHF, PE, pulmonary hemorrhage, atelectasis aspiration or chemical pneumonitis, and lung cancer.
• Respiratory illnesses that mimic CAP include acute exacerbation of COPD, influenza, acute bronchitis, and asthma exacerbation.

Pneumonia Diagnosis

• Collect patient history on age, smoking status, malnourishment, underlying lung disease, medical problems, and recent travel.
• Physical examination should include chest auscultation, checking for dullness to percussion, egophony, tachycardia, tachypnea, pleural rubs, and asymmetric breath sounds as well as increased fremitus.
• Presenting signs and symptoms include cough with or without sputum, high fever, malaise, pleuritic chest pain, rales or bronchial breath sounds, dyspnea, and hemoptysis.

Diagnostic Tests

• Chest X-rays are the most reliable test for confirming pneumonia, as recommended by IDSA/ATS for diagnosing and ruling out complications, and checking for lung inflammation, also confirmed when new infiltrates are found.
• Sputum testing analyzes sputum or phlegm may help identify causative bacteria with treatment plan, but IDSA/ATS guidelines advise against use for outpatients diagnosed with CAP.

Labs

• Perform CBC and differentials, complement fixations, ABGs, viral culture, and blood chemistries.

Further Testing

• Patients with CAP warrant investigation for specific pathogens that could alter standard management decisions, especially when suspected based on clinical and epidemiologic clues.
• Additional tests include urine testing, blood oxygen measurement/pulse oximetry (for all patients with possible CAP), pleural fluid culture, CT scan, and bronchoscopy.

Non-Pharmacologic Therapy

• Includes hydration with increased fluids, reduced activity during the acute phase, and patient education on the disease, treatment, and emergency actions.

Pharmacologic Therapy for Adult Outpatients

• For previously healthy outpatients with no recent antibiotic use:
  • Amoxicillin 1 g po TID x 5 days, unless PCN allergy is present.
  • Doxycycline hyclate 100 mg po BID x 5 days.
  • Macrolide: Azithromycin (Zithromax) 500 mg po once, then 250 mg po QD x 4 days.
• For outpatients with co-morbidities (COPD, diabetes, renal or heart failure, malignancy, EtOH, immunosuppression, or asplenia):
  • Amoxicillin clavulanate (Augmentin) 875 mg po BID OR cefpodoxime 200 mg po BID OR cefuroxime 500 mg po BID, PLUS
    • Azithromycin (Zithromax) 500 mg po once, then 250 mg po daily x 4 days OR
    • Doxycycline hyclate 100 mg po BID x 5 days
  • If cephalosporin/Penicillin allergy, use a respiratory fluoroquinolone, such as:
    • Levofloxacin 750 mg po daily x 5 days OR
    • Moxifloxacin 400 mg po daily x 5 days

Inpatient vs. Outpatient Treatment

• The Curb-65 score helps determine the appropriate treatment setting and assigns one point each for:
  • Confusion.
  • Uremia: BUN > 19 mg/dL (> 7 mmol/L).
  • Respiratory Rate ≥ 30.
  • BP: Systolic BP < 90 mmHg or Diastolic BP ≤ 60 mmHg.
  • Age ≥ 65 years.
• Interpretation of Curb-64 score:
  • A score of 0 or 1 indicates low risk, consider home treatment.
  • A score of 2 indicates short inpatient hospitalization or closely supervised outpatient treatment.
  • A score of 3, 4, or 5 indicates severe pneumonia, hospitalize and consider admitting to intensive care.

Follow Up

• Follow up in 24-48 hours either in person or telephonically to monitor symptom improvement with treatment.
• A follow-up chest x-ray 4-6 weeks after treatment completion is recommended for smokers and patients > 40 years old to rule out bronchogenic carcinoma which may present as pneumonia.

Geriatric Considerations

• Pneumonia is a common infection causing significant morbidity and mortality.
• Geriatric pneumonia is an increasing problem related to the increase in elderly population.
• Pneumonia is a top cause for hospitalization for those 65+.
• Elderly persons are more susceptible and more likely to die from pneumonia than younger populations.
• Older than 65 years of age indicate risk increase.
• Immunity and lung function impairment increases risk.
• Malnutrition and swallowing disorders increase risk.
• A high rate of comorbidities and weakened immune system increases risk.
• Poor functional and bedridden status increases risk.
• The elderly with pneumonia may have fewer or milder symptoms, or none of the classic signs.
• Atypical complaints in the elderly include fatigue, lethargy, decreased appetite, increased falls, and altered mental status (confusion, stupor, or coma), and tachypnea.
• S.pneumoniae is the most common pathogen in the elderly.
• A diagnosis of pneumonia is often delayed in the elderly due to an unusual presentation of symptoms.
• No specific indication for diagnostic workup in the elderly.
• In both the elderly and the general population, conditions such as severity, failure of outpatient antibiotic therapy, immunosuppression, or chronic severe illness determine the diagnosis and course of treatment.
• Antimicrobials remain a cornerstone therapy for all populations, including the elderly.
• Clinical guidelines for CAP do not recommend different treatments for elderly patients; pneumonia treatment guidelines should be followed.
• Smoking cessation counseling benefits the elderly population.
• Immunization against both influenza virus and S.pneumoniae is recommended for patients above 65.

Pneumonia Vaccination

• There are two types of pneumonia vaccines:
  • Pneumococcal conjugate vaccines (PCVs) (15, 20, and 21).
  • Pneumococcal polysaccharide vaccine (PPSV23).
• Guidelines:
  • The CDC recommends PCV15, PCV20, or PCV21 for adults who have never received a PCV and are:
    • Ages 50 years or older.
    • Ages 19 through 49 years with specific risk conditions, such as immunocompromised individuals, those with a cochlear implant, or those with chronic lung, heart, or kidney disease.
  • If PCV15 is used, then administer a dose of PPSV23 as follow-up.
  • If PCV20 or 21 is used, no need for PPSV23.
  • Further guideline information can be found at: Pneumococcal Vaccine Recommendations | Pneumococcal | CDC.