What Is Bacterial Pneumonia?

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Pneumonia is a serious lung condition caused by a virus, bacteria, or fungi. It accounts for the largest number of deaths associated with infections in children.

It is a severe respiratory infection that develops quickly (acute) and affects the small air sacs in the lungs—called the alveoli—causing them to fill up with pus and fluid. 

The alveoli function to exchange oxygen that is taken in by the lungs, transferring it into the blood to be circulated throughout the body. When fluid is in the lungs, it interferes with this process, causing low oxygen levels in the body and making it difficult (and sometimes painful) to breathe.

A child lying on a couch with a blanket and pillow

Elizabeth Salleebauer / Getty Images

This article will explore the symptoms, causes, risk factors, diagnosis, treatment, prevention, complications, and prognosis of bacterial pneumonia.

Symptoms of Pneumonia 

The symptoms of pneumonia can vary from mild, flu-like symptoms to severe breathing problems and serious complications. The severity of pneumonia depends on the particular type of bacteria causing the infection, a person’s overall health, and age. Children less than 2 years old and adults more than 65 years old have an immune system that is often not strong enough to fight off diseases such as pneumonia.

 Common symptoms of bacterial pneumonia include:

  • Cough
  • High fever
  • Dyspnea (difficulty breathing)
  • Tachypnea (increased breathing rate)
  • Tachycardia (fast heart rate)
  • Sweats and chills
  • Shortness of breath
  • Chest pain
  • Muscle pain
  • Joint pain

Bacterial pneumonia is the most common type of pneumonia. It is usually more serious than viral pneumonia and often requires medical intervention.

In bacterial pneumonia, the fever can spike suddenly to as high as 105 degrees F, causing profuse sweating, rapid heart rate, and an increase in breathing rate. A person can become confused or delirious, and lips and nail beds are often slightly bluish in color from lack of adequate oxygen.


There are typical and atypical bacterial causes of pneumonia, including the pathogens (germs) that are the underlying cause.

Typical bacterial pneumonia is the type of pneumonia most often seen by healthcare providers. It is more severe than atypical pneumonia. Common bacterial causes of typical pneumonia include:

  • Streptococcus pneumoniae
  • Haemophilus influenzae
  • Staphylococcus aureus
  • Group A streptococci
  • Moraxella catarrhalis
  • Anaerobes, and aerobic gram-negative bacteria

Atypical pneumonia is often referred to as “walking pneumonia.” Its symptoms are much milder than typical pneumonia and are often caused by: 

A person is more apt to be exposed to certain types of pathogens (bacteria) in different environments. For example:

  • Legionella pneumonia typically comes from contaminated water and air conditioning systems.
  • Streptococcus pneumonia, mycobacteria, mycoplasma, and chlamydia are often found in crowded environments, such as homeless shelters and jails.
  • Coxiella burnetii can be transmitted to humans from cats, sheep, and cattle.
  • Chlamydia psittaci is often the result of exposure to birds such as turkeys, ducks, and chickens.

Risk Factors

People at high risk for bacterial pneumonia include:

  • Adults ages 65 and older
  • Children younger than 2 years old
  • People with certain medical conditions (including a heart condition, asthma and other lung disorders, and HIV/AIDS)
  • Those with autoimmune diseases
  • Smokers
  • People receiving chemotherapy (cancer treatment)
  • Organ recipients (those who have had organ transplants)     
  • Pregnant women


Pneumonia can be difficult to diagnose because symptoms often mimic those of disorders such as the common cold or influenza. To diagnose pneumonia, the healthcare provider will get a thorough history, do a physical examination, and perform some tests.  

Medical History

Because certain environments can expose a person to different pathogens (germs), the diagnostician will ask questions about frequent travel, exposure to various vectors (such as certain types of birds), as well as any close contact with other sick people.

Physical Exam

A physical examination will be performed to check for signs and symptoms of pneumonia. The healthcare provider will listen to the lungs with a stethoscope, observing for any telltale signs of pneumonia such as wheezes, crackling, or rumbling sounds when a person breathes in or out.  

Diagnostic Tests

Several different types of diagnostic tests may be performed to diagnose pneumonia, including:


Treatment of bacterial pneumonia depends on the severity of symptoms, the type of pathogen (bacteria), and other factors. Most of the time, pneumonia can be treated in a home setting, but in severe cases, hospitalization may be needed.

Treatment may include:

  • Antibiotics
  • Oxygen therapy
  • Mechanical ventilators
  • Pain medication
  • Expectorants
  • Medications to help ease breathing problems

Home instructions to promote recovery from bacterial pneumonia may include:

  • Controlling fever, often with over-the-counter antipyretic medications such as Tylenol
  • Eating a healthy diet
  • Increasing fluids
  • Getting plenty of rest

Antibiotics for Pneumonia

If you receive antibiotics as part of your treatment modality for pneumonia, be sure to take them exactly as prescribed and finish your full prescription. Stopping the use of antibiotics midway through the treatment regime lends itself to superinfections (infection occurring on top of previous infection) and creates bacteria which are ineffective for treating certain types of germs.


Vaccinations can help prevent certain types of bacterial pneumonia, including Streptococcus pneumoniae, the most common cause of bacterial pneumonia in children from 3 months to 3 years of age. The pneumococcal vaccine series begins at age 2 months and is said to significantly lower the rate of pneumonia from this bacteria.

The pneumococcal vaccine is also recommended for anyone at high risk of getting bacterial pneumonia (such as children less than 5 years old and adults ages 65 and older).

Vaccinations for other childhood diseases that can lead to bacterial pneumonia include those for:


Complications are conditions or symptoms caused by a person’s primary illness. The complications of bacterial pneumonia may include:

  • Acute respiratory distress syndrome
  • Respiratory failure
  • Lung abscesses
  • Sepsis
  • Bronchiectasis
  • Necrotizing pneumonia
  • Destruction and scarring of lung tissue
  • Emphysema
  • Bacteremia

Note, severe complications of pneumonia are more likely in those who are immune compromised or otherwise at high risk (such as small children and elderly adults).


The prognosis is the expected outcome of treatment, based on clinical research studies. The prognosis of bacterial pneumonia varies widely, depending on the type of pathogen that causes pneumonia, the age and general health of the person with pneumonia, and other factors. 

A healthy adult usually recovers promptly from pneumonia when given proper care. But there can be some long-term health issues, such as:

  • A decrease in normal ability to exercise
  • A mental decline
  • Worsening of heart disease (for those with preexisting cardiovascular disease)
  • A decline in the overall quality of life (for months or even years)

Additionally, children who have pneumonia may develop chronic (long-term) lung disorders.

Your healthcare provider can talk to you about your prognosis, based on your risk factors (if any), as well as other influences linked with the prognosis of pneumonia.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Sherry Christiansen
Sherry Christiansen is a medical writer with a healthcare background. She has worked in the hospital setting and collaborated on Alzheimer's research.