Pneumonia: Causes, Symptoms, Diagnosis, Treatment, and Prevention

Introduction

Pneumonia is a serious infection that affects the lungs, causing inflammation and fluid buildup in the air sacs (alveoli). It can make breathing difficult and can range from mild to life-threatening. Pneumonia affects people of all ages but is particularly dangerous for infants, older adults, and people with weakened immune systems.

What Is Pneumonia?

Pneumonia is an infection of the lungs caused by bacteria, viruses, fungi, or other microorganisms. When the infection reaches the lungs, the air sacs become filled with pus and fluid, making it difficult for oxygen to pass into the bloodstream.

Types

Community-Acquired Pneumonia (CAP)

Bacteria (especially Streptococcus pneumoniae)

Viruses (like influenza or RSV)

Mycoplasma pneumoniae (causes walking pneumonia)

Hospital-Acquired Pneumonia (HAP)

This occurs during a hospital stay, typically 48 hours or more after admission. It can be more severe because the bacteria causing it are often resistant to antibiotics.

Ventilator-Associated Pneumonia (VAP)

Seen in patients who are on mechanical ventilation (breathing machines). It’s a serious form of hospital-acquired pneumonia.

Aspiration Pneumonia

Occurs when food, saliva, vomit, or liquids accidentally enter the lungs instead of the stomach. This type is more common in people with swallowing difficulties.

Fungal Pneumonia

Caused by fungi such as Histoplasma or Pneumocystis jirovecii. It mainly affects people with weakened immune systems, such as HIV patients or organ transplant recipients

Causes

Bacteria

Streptococcus pneumoniae (most common)
Haemophilus influenzae
Mycoplasma pneumoniae
Chlamydia pneumoniae
Legionella pneumophila (causes Legionnaires’ disease)

Viruses

Influenza (Flu)
Respiratory Syncytial Virus (RSV)
Coronaviruses (including COVID-19)
Adenovirus

Fungi

Histoplasma capsulatum
Cryptococcus
Pneumocystis jirovecii

Other Causes

Aspiration (food or liquids entering lungs)
Chemical or toxic substances

Risk Factors

Infants and young children
Elderly adults (over 65 years)
People with chronic diseases (like asthma, COPD, diabetes)
Weakened immune system (HIV, chemotherapy, transplant patients)
Smokers
Hospitalized or ventilated patients
Malnourished individuals

Symptoms

Common Symptoms Include:

High fever with chills
Persistent cough (with green, yellow, or bloody mucus)
Chest pain (especially when breathing or coughing)
Shortness of breath or difficulty breathing
Fatigue or weakness
Rapid breathing and heartbeat
Sweating and shivering
Loss of appetite
Confusion (especially in elderly people)

In Children:

Fast or labored breathing
Grunting or wheezing
Fever and irritability
Poor feeding or vomiting

Diagnosis

Physical Examination

Listening to the lungs with a stethoscope for crackling or wheezing sounds.

Chest X-ray

Confirms the presence and extent of lung infection.

Blood Tests

Check for signs of infection and identify the type of organism.

Sputum Test

Analyzes mucus from the lungs to detect bacteria or viruses.

Pulse Oximetry

Measures oxygen levels in the blood.

CT Scan (in severe cases)

Provides detailed lung images for complicated cases.

Bronchoscopy

Used if the infection does not respond to treatment to check the airways directly.

Treatment

The treatment depends on the type and severity of pneumonia and the age and health of the patient.

Bacterial Pneumonia

Treated with antibiotics such as amoxicillin, azithromycin, or doxycycline.
Improvement is usually seen within 3–5 days.

Viral Pneumonia

Usually managed with rest, fluids, and antiviral medications (in severe cases like influenza or COVID-19).

Fungal Pneumonia

Treated with antifungal medicines like fluconazole or amphotericin B.

Supportive Care

Rest and hydration
Oxygen therapy (if oxygen levels are low)
Pain relievers and fever reducers (paracetamol, ibuprofen)
Cough medicine (only if cough is severe)
In severe cases, hospitalization may be required for IV antibiotics, fluids, or ventilator support.

Complications

Pleural effusion (fluid around lungs)
Lung abscess (pus in lung tissue)
Sepsis (infection spreads to the blood)
Respiratory failure
Organ damage
Death, especially in high-risk groups

Prevention

Vaccination

Pneumococcal vaccine: Protects against Streptococcus pneumoniae.
Influenza vaccine: Prevents flu-related pneumonia.
COVID-19 vaccine: Reduces risk of viral pneumonia.
Hib vaccine: Protects children from Haemophilus influenzae type b.

Good Hygiene

Wash hands regularly with soap.
Avoid touching your face and mouth frequently.
Cover your mouth when coughing or sneezing.

Healthy Lifestyle

Eat a balanced diet to strengthen the immune system.
Quit smoking, as it damages the lungs.
Exercise regularly and get enough sleep.

Avoid Exposure

Stay away from people with respiratory infections.
Keep your living area clean and well-ventilated.

Pneumonia in Children

Children, especially under the age of five, are at high risk. In developing countries, pneumonia is a leading cause of death among children. The main causes are bacterial and viral infections.

Warning Signs in Children:

Fast or difficult breathing
Chest indrawing (chest moving inward while breathing)
Inability to feed or drink
Bluish lips or fingertips

Treatment:

Oral or injectable antibiotics (for bacterial pneumonia)
Adequate fluids and rest
Hospitalization in severe cases
Vaccination, breastfeeding, and proper nutrition play a vital role in prevention.

Home Remedies and Self-Care Tips

Drink warm fluids to loosen mucus.
Use a humidifier for easier breathing.
Rest adequately to allow the body to heal.
Avoid smoking and secondhand smoke.
Eat nutritious foods rich in vitamins A, C, and zinc.

When to See a Doctor

Seek immediate medical attention if you experience:

Difficulty breathing
Chest pain
Persistent high fever
Confusion or bluish lips
Coughing up blood

Prognosis (Outlook)

Most healthy individuals recover from pneumonia within 1 to 3 weeks with proper treatment. However, recovery may take longer in elderly or immunocompromised patients. Timely treatment and prevention are key to reducing the risk of severe illness.

Pneumonia