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Pneumococcal Infections


Larry M. Bush

, MD, FACP, Charles E. Schmidt College of Medicine, Florida Atlantic University

Last full review/revision Jun 2019| Content last modified Jun 2019
Click here for the Professional Version

Pneumococcal infections are caused by the gram-positive, sphere-shaped (coccal) bacteria (see figure How Bacteria Shape Up) Streptococcus pneumoniae (pneumococci). These bacteria commonly cause pneumonia, meningitis, sinusitis, and middle ear infection.

  • Pneumococcal bacteria are dispersed in the air when infected people cough or sneeze.

  • Pneumococcal infections usually cause fever and a general feeling of illness, with other symptoms depending on which part of the body is infected.

  • Diagnosis may be based on symptoms or identification of the bacteria in samples of infected material.

  • Young children are routinely vaccinated against these infections, and vaccination is recommended for all people at high risk.

  • Penicillin or another antibiotic is usually effective treatment.

(See also Overview of Bacteria.)

There are more than 90 types of pneumococci. However, most serious infections are caused by only a few types.

Pneumococci commonly reside in the upper respiratory tract of healthy people, their natural host, particularly during the winter and early spring. The bacteria spread to other people when they do the following:

  • Inhale infected droplets dispersed by sneezing or coughing

  • Come in close contact with an infected person

Spread is more likely among self-contained groups of people, such as people who live, stay, or work in nursing homes, prisons, military bases, shelters for the homeless, or day care centers.

Risk factors

Certain conditions increase the risk of developing and the severity of pneumococcal infections:

Influenza and chronic bronchitis may damage the lining of respiratory tract and thus make it easier for pneumococcal bacteria to cause infection.

Also, older people, even if healthy, tend to have more severe symptoms and complications when they get a pneumococcal infection.

Pneumococcal vaccination is recommended for people with one or more risk factors.

Symptoms and Diagnosis

Symptoms of pneumococcal infections vary depending on the site of the infection.

Most pneumococcal infections occur in the

The bacteria may also spread to and through the bloodstream (called bacteremia). Infections may occur in the tissues covering the brain and spinal cord (meningitis) or, less often, in heart valves (endocarditis), bones, joints, or the abdominal cavity.

Pneumococcal pneumonia

Often, symptoms of pneumococcal pneumonia begin suddenly. People have fever, chills, a general feeling of illness (malaise), shortness of breath, and a cough. The cough brings up sputum that is rust-colored.

Commonly, sharp, stabbing chest pains occur on one side. Deep breathing and coughing make the pains worse. In about 40% of people, fluid accumulates between the layers of tissue that cover the lungs (called pleural effusion). Pleural effusion may contribute to chest pain and make breathing difficult.

Chest x-rays are taken to look for signs of pneumonia. Doctors take a sample of sputum and examine it under a microscope. A sample of sputum, pus, or blood may be sent to a laboratory to grow (culture) bacteria. Pneumococcal bacteria are easily identified. They are also tested to see which antibiotics are effective (a process called susceptibility testing).

Pneumococcal meningitis

People with pneumococcal meningitis have fever, headache, and a general feeling of illness (malaise). They have a stiff neck that makes lowering the chin to the chest painful and difficult, but this problem is not always obvious early in the disease.

Unlike older children and adults, most infants with meningitis do not have a stiff neck. They may only be reluctant to eat and be irritable or sluggish.

Pneumococcal meningitis may lead to complications, such as

  • Hearing loss (in up to 50% of people)

  • Seizures

  • Learning disabilities

  • Mental dysfunction

The diagnosis of pneumococcal meningitis requires a spinal tap (lumbar puncture) to obtain a sample of the fluid that surrounds the brain and spinal cord (cerebrospinal fluid). The sample is checked for signs of infection, such as white blood cells and bacteria.

Pneumococcal otitis media

Pneumococcal otitis media causes ear pain and a red, bulging eardrum or pus behind the eardrum. These infections can cause

Pneumococcal bacteria causes about 30 to 40% of all cases of otitis media in children. Pneumococcal otitis media commonly recurs.

The diagnosis of pneumococcal otitis media is usually based on symptoms and results of a physical examination. Cultures and other diagnostic tests are usually not done.


Two types of pneumococcal vaccines are available:

  • A conjugate vaccine (PCV13) that protects against 13 types of pneumococci

  • A nonconjugate polysaccharide vaccine (PPSV23) that protects against 23 types of pneumococci

If children under 5 years old do not have a spleen or if their spleen is not functioning, they may be given antibiotics (such as penicillin) in addition to the vaccine. In such cases, antibiotics may be continued throughout childhood and into adulthood.

Conjugate vaccine (PCV13)

PCV13 is routinely recommended for

  • All children

  • All adults aged 65 and over

PCV13 is also recommended for people aged 6 to 64 who have any of the following high-risk conditions:

  • An injury or other disorder that causes spinal fluid to leak

  • Sickle cell disease or similar disorders of red blood cells

  • A weakened immune system (for example, because of a congenital disorder, certain chronic kidney disorders, HIV infection, leukemia, lymphomas, other cancers, or use of drugs that suppress the immune system)

Nonconjugate vaccine (PPSV23)

PPSV23 is recommended for

  • All adults aged 65 and over

PPSV23 is also recommended for people aged 2 to 64 who have any of the following:

  • Any of the high-risk conditions listed above

  • A chronic lung disorder (including asthma)

  • A chronic heart disorder (except high blood pressure)

  • A chronic liver disorder

  • Chronic alcohol abuse

  • Cigarette smoking


  • Penicillin or another antibiotic

Penicillin (or the related drugs, ampicillin and amoxicillin) is used for most pneumococcal infections. It is usually taken by mouth but, if the infection is severe, may be given intravenously.

Pneumococci that are resistant to penicillin are becoming more common. Thus, other antibiotics, such as ceftriaxone, cefotaxime, fluoroquinolones (such as levofloxacin), vancomycin, or omadacycline, are often used. Vancomycin is not always effective against meningitis caused by pneumococci. Thus, people with meningitis are usually given ceftriaxone or cefotaxime, rifampin, or both, as well as vancomycin.

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