Pneumonia Basics

What is pneumonia? An inflammatory condition of the lungs, most often caused by infectious organisms, such as bacteria or viruses. In the US, there are an estimated 5-10 million cases of pneumonia each year and pneumonia is the 4th leading cause of hospitalization.

What are the types of pneumonia? Doctors classify pneumonia by the (1) cause, (2) location in the lung, or (3) clinical setting.

  • Causes: Pneumonia can be caused by bacteria, viruses, fungi, parasites, chemicals, and other agents.
  • Location: Lobar (confined to a specific location, or lobe) versus interstitial (more widely spread throughout the lungs).
  • Clinical Setting: Includes Community-acquired Pneumonia (CAP), Hospital-acquired Pneumonia (also called nosocomial pneumonia), Ventilator-associated Pneumonia (VAP), Aspiration Pneumonia (from gastric content entering the lungs), Opportunistic Pneumonia (in people with defective immune systems), Atypical Pneumonia (based on symptoms and infectious cause), and Occupational/Regional (some jobs or places may predispose you to a certain type of pneumonia).

What are the symptoms of pneumonia? For some pneumonias, such as Pneumococcal Pneumonia (from Streptococcus pneumoniae, the most common cause of CAP), the symptoms develop very rapidly- hours rather than days. Common symptoms of pneumonia include:

  1. Fever (often after a shaking chill)
  2. Chest pain (on the side of the pneumonia), particularly when coughing or breathing deeply
  3. Shortness of breath
  4. Cough (often with darkened mucus)
  5. Nausea, vomiting, and muscle aches

Elderly patients with pneumonia may have fewer symptoms or less rapid onset, and experience confusion or lethargy. Atypical Pneumonia characteristically has more slowly progressive symptoms (often with flu-like symptoms first), dry hacking cough, and less severe chest pain.

How is pneumonia diagnosed? Your doctor will take a thorough history from you, and perform a physical examination. Listening to the lungs with a stethoscope, palpating your chest, and percussing your lungs (tapping with fingers) help your doctor determine if you have pneumonia. The chest x-ray (or maybe chest CT) will give your doctor a visual image of the location and type of pneumonia. A sputum test might be ordered to help identify the cause. Blood tests, such as CBC (to look for abnormal White Blood Cell count) or blood cultures (to look for infection spread to the bloodstream) might be taken. Sometimes, your doctor might need to do invasive testing, such as bronchoscopy, thoracentesis, or lung biopsy.

How is pneumonia treated? The treatment approach in patients with pneumonia involves several decisions by your doctor:

  1. Do you need to be in the hospital, or can you be treated at home?
  2. What type of pneumonia is it or is the most likely?
  3. Do you have any underlying health issues?
  4. What is the best choice of antibiotic (or antimicrobial), if any?

What are the complications of pneumonia? Although the vast majority of pneumonias respond well to treatment, some cases develop complications. These include:


  1. Lung abscess (a thick-walled, pus-filled cavity in the lung)
  2. Atelectasis (deflated lung)
  3. Respiratory failure (inability to keep up the demands of breathing)
  4. Bacteremia (bacteria spread to the blood)
  5. Pleural effusion (fluid in the space between the lungs and chest wall)
  6. Empyema (pus in the pleural space)
  7. Pneumothorax (collapsed lung)
  8. Dehydration
  9. Hypoxia (low oxygen)
  10. Kidney complications and electrolyte imbalances
  11. Heart problems, including arrhythmia (abnormal heart rhythm) and heart attack

Is there prevention? Yes, there are things you can do to help decrease your chance of getting pneumonia.

  1. Good hygiene. Wash your hands and don’t touch infected surfaces. Using ordinary soap is sufficient. Alcohol-based gels are also effective for everyday use.
  2. Avoid transmission. Stay away from sick people (if possible).
  3. Vaccination. A single dose of the Pneumococcal Polysaccharide vaccine works for most adults in protecting against Pneumococcal Pneumonia. A revaccination after 6 years may be needed. Yearly Influenza vaccination (“flu shot”) may reduce your risk of pneumonia.
  4. Healthy lifestyle. Eat a well-balanced diet, and don’t smoke, use illicit drugs or drink alcohol excessively.

Where can I learn more?

National Institutes of Health/National Institute of Allergy and Infectious Diseases

Centers for Disease Control and Prevention (CDC)

American Lung Association

National Heart Lung and Blood Institute