Community-acquired pneumonia

Disease Description (Causes and Symptoms)

• Definition: Community-acquired pneumonia (CAP) is pneumonia acquired in the usual living environment and is distinguished from healthcare-associated infections such as those acquired in nursing homes or hospitals. It can occur at any age, but the risk of becoming severe is higher in infants and young children (especially those under 2 years of age) and older adults.
• Main causes: Streptococcus pneumoniae (pneumococcus) is the most common cause, accounting for approximately one-third of all cases. Other causes include Mycoplasma pneumoniae (mainly in younger people), Haemophilus influenzae, viruses (such as influenza and respiratory syncytial virus), and Legionella. The causative organism may vary depending on underlying conditions (chronic lung disease, heart failure, immunosuppression, etc.).
• Pathophysiology (brief): Pathogens invade the airways and alveoli and cause inflammation → exudate and inflammatory cells accumulate in the alveoli → impaired gas exchange and systemic symptoms occur.
• Main symptoms: Cough (possibly with sputum), fever, chest pain (worsening with breathing), shortness of breath, generalized weakness and fatigue. Crackles or decreased breath sounds may be observed on auscultation.

Treatment Methods

• Diagnostic tests (to consider before/during treatment)
  • Chest X-ray: To identify pulmonary infiltrates (the basic diagnostic test). Chest CT if necessary.
  • Sputum Gram stain and culture, blood cultures (in hospitalized or severe cases), urine antigen tests (S. pneumoniae, Legionella), and viral testing (during periods of outbreaks).
  • Oxygen saturation (pulse oximeter), arterial blood gas if necessary, and blood tests (CBC, CRP/ESR, BUN/creatinine, etc.).
• Antibiotics (empirical treatment; varies depending on the region, resistance rates, and patient risk factors)
  • Outpatient treatment (healthy adults without comorbidities): Oral penicillin-class antibiotics (e.g., amoxicillin) or amoxicillin-clavulanate; a macrolide (azithromycin) or doxycycline may be added if necessary (or, if selecting macrolide/doxycycline monotherapy, local drug resistance should be considered).
  • Outpatient treatment (with comorbidities or recent antibiotic use): Respiratory fluoroquinolone monotherapy (levofloxacin, moxifloxacin) or a beta-lactam (e.g., amoxicillin-clavulanate) plus a macrolide.
  • Inpatient treatment (general ward): IV beta-lactam (ceftriaxone, cefotaxime, ampicillin-sulbactam, etc.) plus a macrolide, or respiratory fluoroquinolone monotherapy.
  • Severe cases/ICU: If severe pathogens are considered (e.g., risk of Pseudomonas), the antibiotic coverage is broadened; the standard is an IV beta-lactam plus a macrolide or a beta-lactam plus a fluoroquinolone. If there is a risk of MRSA, adding an anti-MRSA drug (e.g., vancomycin) may be considered.
• Antibiotic duration: Administer for at least 5 days after clinical stability (defervescence, improvement in shortness of breath, normalization of respiratory rate and blood pressure, etc.) is achieved, and treatment may be discontinued when the patient has remained clinically stable for 48–72 hours. However, 7–10 days or longer may be required depending on the individual condition and presence of complications.
• Supportive care: Oxygen therapy (in cases of hypoxemia), fluid management, analgesics and antipyretics, management of bronchial secretions (promoting sputum expectoration), and smoking cessation advice. Mechanical ventilation and hemodynamic support may be required in severe cases.
• Monitoring and follow-up: Monitor the course of symptom improvement; follow-up chest X-rays if necessary (especially in older adults, smokers, or cases of persistent infiltrates, an examination 4–8 weeks later is recommended).
• Preventive treatment and vaccination: Influenza and pneumococcal vaccines are recommended for high-risk groups (infants and young children, people aged 65 and older, and people with chronic diseases). Consult healthcare professionals regarding vaccination recommendations based on the region and individual medical history.

Precautions for This Disease

• When emergency care is immediately required: Severe shortness of breath, oxygen saturation (SpO2) below 90%, altered consciousness, severe hypotension (fainting or orthostatic hypotension), persistent high fever (not improving even with antipyretics), etc.
• Complications: Sepsis, respiratory failure, lung abscess, pleural effusion and empyema (purulent pleuritis), pneumothorax, worsening bronchiectasis, etc. The risk of severe disease and death is increased in older adults.
• Precautions for self-care: Take prescribed antibiotics for the entire period instructed by the healthcare professional, drink sufficient fluids and rest, do not smoke, and visit a healthcare institution immediately if symptoms worsen.

Outpatient Visit Checklist (Including Preparation Items and Example Questions)

• Preparation items
  • A list of currently taken medications (including prescription drugs, over-the-counter medications, herbal medicines, and nutritional supplements) or medication packages
  • A summary of past medical history (chronic diseases, allergies, and recent hospitalizations or surgeries)
  • A record of when symptoms began; changes in fever, cough, and sputum; the degree of shortness of breath (whether worsening or improving); and whether shortness of breath occurs during exercise
  • Recent hospital test results, if available (such as chest imaging and blood test results)
  • Sputum collection if possible (if sputum is produced before the appointment, store it in a container and bring it with you)
• Examples of information and questions that may be useful to provide to the doctor during an outpatient visit
  • Symptoms (when they began and what caused them to worsen), sputum color and amount, degree of shortness of breath (at rest or during activity), and fever pattern

General Example Questions to Ask the Doctor

• "How can you determine whether the cause of this pneumonia is bacterial or viral?"
• "What are the main side effects of the antibiotic I was prescribed, and are there any foods or medications I should specifically avoid while taking it?"
• "How many days does it usually take for symptoms to improve after starting antibiotics? When should I return if there is no improvement?"
• "How do you determine whether hospitalization is needed or whether outpatient treatment is sufficient?"
• "What is the prognosis? What lifestyle habits should I follow to reduce the risk of complications?"

Examples of Disease-Specific Questions

• "Considering my age and underlying conditions (e.g., diabetes or chronic lung disease), what antibiotic combination and treatment duration are recommended?"
• "When does the chest X-ray infiltrate caused by pneumonia usually disappear completely, and when should I have follow-up imaging?"

(Note: Diagnosis and treatment vary depending on the individual patient's condition, local drug resistance rates, and clinical guidelines. Consult the healthcare professional in charge for accurate prescriptions and decisions.)