Streptococcus pneumoniae is a type of bacteria that can cause pneumococcal disease.

There are more than 100 strains of this bacteria, though not all of them lead to infections. People can carry the bacteria in their respiratory tract without even knowing it.

Read on to learn more about S. pneumoniae bacteria (pneumococci), including the types of diseases it may cause and how you can protect yourself and others from infection.

Pneumococci bacteria commonly live in the human respiratory tract. The Centers for Disease Control and Prevention (CDC) estimates that between 5% and 90% of people may be carriers, depending on age and setting. Children tend to carry the bacteria longer than others.

For example, 20% to 60% of school-aged children may carry this bacterium, while 5% to 10% of adults without children may carry it. The estimated carrier rate among military service personnel is slightly higher at 50% to 60%.

Despite its prevalence, only a small number of pneumococci lead to related infections. Like other respiratory illnesses, pneumococcus infections can spread via coughing and sneezing.

However, the CDC also acknowledges that little is known about how some carriers may develop natural immunity.

Who’s most at risk for pneumococcal disease?

Older adults and young children may be at a higher risk of developing pneumococcal disease. Other risk factors include underlying health conditions that may impact your immune system. These include:

Smoking cigarettes and excessive alcohol use may also increase your risk.

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Pneumococcus can cause various infections that affect your lungs, brain, and other parts of your body. The symptoms may also vary depending on the body part affected.


Pneumococcal pneumonia is a type of lung infection. It leads to approximately 150,000 hospitalizations in the United States each year.

Symptoms may include:

  • cough
  • breathing difficulties
  • rapid breathing
  • chest pain
  • confusion
  • fever or chills

This type of pneumonia may also lead to life threatening complications, such as:

  • infection that spreads from the lungs to your chest cavity (empyema)
  • blockage of air to your lungs (endobronchial obstruction)
  • pus buildup (lung abscess)
  • lung collapse (atelectasis)
  • inflammation of the heart’s outer lining (pericarditis)


Meningitis describes a serious and potentially fatal infection of the brain and spinal cord. Symptoms may include:


Pneumococcal bacteremia describes a blood infection. This infection can lead to serious complications, including death.

Symptoms of this blood infection include fever, chills, and low alertness.


Sepsis describes your body’s overall response to an infection. Pneumococcal disease may also cause sepsis.

Symptoms of sepsis include:

  • fever
  • extreme chills
  • clamminess or sweating
  • significant muscle and joint pain
  • shortness of breath
  • increased heart rate
  • confusion

If left untreated, sepsis may cause permanent damage to your:

  • brain
  • heart
  • kidneys
  • lungs


While there are many causes of sinusitis, some sinus infections are due to pneumococcus.

Symptoms of sinusitis can include:

While rare, complications of sinusitis include bone and eye infections, as well as painful abscesses.


Bronchitis refers to inflammation in the airways (bronchial tubes) of your lungs. While usually due to viral infections, bacterial infections like pneumococcus may also lead to bronchitis.

Symptoms include:

  • a productive cough
  • wheezing
  • shortness of breath
  • chest pain
  • low grade fever

Otitis media

Pneumococcal otitis media is a type of middle ear infection. This is one of the mildest and most common pneumococcal infections.

Symptoms include:

  • ear pain
  • swelling and redness of the eardrum
  • fever
  • fatigue

While a physical exam and your symptoms can help a doctor diagnose pneumococcal disease, the only way to know if you have this type of bacterial infection is through lab testing.

A doctor will need to test a sample of your body fluids. They may do this through a urinary antigen test, which looks for C-polysaccharides in the sample. C-polysaccharides are antigens found on the cell walls of all pneumococci.

Another common method is gram staining. This method involves taking a fluid sample via a swab. They may use a variety of fluids, including urine, blood, and sputum.

Since bacteria cause pneumococcal disease, the main treatment is a course of oral antibiotics. Other treatments may involve supportive care or treating specific symptoms.

Depending on the type of infection you have, other treatment measures could include over-the-counter pain relievers, decongestants, and drinking plenty of fluids.

Although the protection rate is not 100%, pneumococcal vaccines can still help protect against most strains and related infections in both children and adults.

There are four available vaccines against pneumococcus. Which vaccine is right for you will depend on several factors, such as:

  • your age
  • whether you have any underlying conditions
  • whether you have had previous pneumococcal vaccines

Talk with a medical professional to determine the vaccine or dosage that is best for you or your child.

Pneumococcal vaccines are safe for most people. But temporary side effects may occur, such as:

  • redness, swelling, and pain at the injection site
  • muscle aches
  • chills
  • fever
  • fatigue
  • headache
  • loss of appetite

How often do I need a pneumococcus vaccine?

The number of times a doctor may recommend the pneumococcal vaccine depends on your vaccination history, age, and medical history.

The CDC recommends an initial 3-dose series for infants at ages 2, 4, and 6 months, followed by a booster between 12 and 15 months. But you may need an additional booster later in life if you’re over 65 years old or have a weakened immune system.

Can I take antibiotics as a preventive measure?

No. You should only take antibiotics if you have a confirmed bacterial infection. Antibiotics don’t work against viral and fungal infections, and they can’t prevent bacterial infections from occurring. They also come with potential side effects.

Taking these medications when unnecessary can increase your risk of developing antibiotic resistance. This can make it harder for your body to fight infections in the future, while also making antibiotics not work as well.

Can I get pneumococcal disease more than once?

Yes. For example, children may be more prone to pneumococcal otitis media, with repeated infections possibly requiring the need for ear tubes.

Is pneumococcus fatal?

Pneumococcus can be fatal. According to the CDC, there were 3,250 deaths related to pneumococcal meningitis and bacteremia in the United States in 2019. About 1 in 20 people with pneumococcal pneumonia die from this lung infection.

Streptococcus pneumoniae is a common type of bacteria that many people carry in their respiratory tract without knowing it.

While not all strains cause illness, some may lead to a variety of pneumococcal diseases that can affect your lungs, brain, bloodstream, and other parts of your body. Some may even lead to life threatening complications.

To protect yourself:

  • Stay away from others who may be sick.
  • Follow common public health recommendations such as frequent handwashing and physical distancing.
  • Talk with a doctor to see if you’re up to date on your vaccinations.