What is Pneumonia?

Pneumonia is an acute respiratory infection that causes inflammation in the air sacs (alveoli) in one or both of the lungs. The air sacs of a pneumonia patient fill up with pus and fluid, resulting in feeling pain when breathing and limited oxygen intake. Its seriousness ranges from mild to life-threatening. Pneumonia causes 14% of the deaths in children under five years old and killed 740.180 children in only 2019. It can be prevented, and in the case of pneumonia caused by bacteria, it can be treated with antibiotics. 

There are more than 30 causes for why a person may have pneumonia. The main cause types used for grouping the disease are: 

  1. Bacterial pneumonia: The most common bacteria for it is Streptococcus pneumoniae. It generally happens when the body is weakened in some way and the bacteria are able to work their way into the lungs. It can affect all ages, but there are some factors that increase the risk.
  2. Viral pneumonia: It is caused by many different viruses including the influenza virus and is responsible for about one-third of all the cases.
  3. Mycoplasma pneumonia: This type has different symptoms and physical signs. It is caused by the bacterium Mycoplasma pneumoniae. It affects all age groups and generally causes a mild and widespread pneumonia.
  4. Other pneumonias: There are other less common pneumonias that may be caused by other infections including fungi.

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Risk groups for pneumonia

A person can get pneumonia regardless of their age. But the following groups have the highest risk

  • Adults older than 65 
  • Children younger than 2
  • People with certain medical conditions
  • Smokers

Pneumonia symptoms

These symptoms may vary between mild and severe, depending on several factors such as overall health and the type of germ causing the infection. 

  • Pain in the chest when breathing or coughing 
  • Changes in mental awareness (seen in elderly patients)
  • Cough (may have phlegm)
  • Fatigue
  • Nausea, vomiting
  • Diarrhea 
  • Shortness of breath 
  • Fever, sweating, chills


Pneumonia diagnosis is usually made based on the state of the illness determined by a physical exam, and the patient's recent health history. But, the following tests may be used to confirm the diagnosis:

  • Chest x-ray: looks for the location and the inflammation amount in the lungs.
  • Blood tests: confirms the infection and tries to identify the germ causing the illness.
  • Sputum test: a mucus sample is tested to look for the source of the infection.
  • Pulse oximetry: measures the oxygen level in the blood (because pneumonia can stop the lungs from moving enough oxygen into the blood)

Some additional tests also may be used if the patient is high-risk or hospitalized:

  • Arterial blood gas test: measures the amount of oxygen in a blood sample from an artery and is more accurate than pulse oximetry.
  • CT scan: to look for abscesses or other complications in the lungs.
  • Bronchoscopy: used to look into the lungs' airways. 
  • Pleural fluid culture: a small amount of fluid is taken from around the tissues surrounding the lung to identify the bacteria causing the pneumonia.

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Pneumonia treatment

Pneumonia generally is treated with antibiotics. Hospitalization is recommended only for severe pneumonia cases. 

In mild cases, getting a lot of rest and drinking plenty of liquids is advised, in addition to using antibiotics. 


Pneumonia may get very serious and even cause death. Some critical complications are: 

  • Lung abscesses: pockets of pus that form around or inside the lungs, which may need to be drained surgically.   
  • Sepsis: infection getting into the bloodstream. May lead to organ failure.
  • Respiratory failure: requires the use of a ventilator.
  • Acute respiratory distress syndrome: a severe form of respiratory failure.


It is possible to reduce the risk of getting pneumonia by being careful about a few simple things. First of all, as the flu is a common cause of pneumonia, getting a flu shot every year may help. Also, children younger than 5 and adults older than 65 should get vaccinated against pneumococcal pneumonia (a common bacterial pneumonia form). 

Adding to this, paying attention to general health and hygiene is also vital. Measures like frequent hand washing and not smoking can be helpful as well. 


  1. "Pneumonia", World Health Organization, 2021.
  2. "Pneumonia - Symptoms & Causes", Mayo Clinic, 2020.
  3. "Pneumonia", United Kingdom National Health Service, 2019.
  4. "Pneumonia Symptoms and Diagnosis"American Lung Association, 2021.
  5. "Pneumonia", John Hopkins Medicine.

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