What is Pneumococcus?

Pneumococcal disease is an infection caused by the bacterium Streptococcus pneumoniae (S. pneumoniae). S. pneumoniae bacteria are gram-positive, lancet-shaped, facultative anaerobic bacteria, and currently over 90 known serotypes have been identified. Only a few serotypes cause most pneumococcal infections, but nearly all serotypes are capable of causing serious disease.⁽¹⁾

S. pneumoniae are often found in the airways, and up to 90% of healthy people may have the bacteria present in the nasopharynx (upper throat area behind the nose). As many as 20-60% of all school-age children can be carriers of the bacterium.⁽²⁾ Colonization of S. pneumoniae in the nasopharynx tends to be maximal by age 3 years and decline thereafter. S. pneumoniae colonization in adults is usually acquired through exposure of children, but the rates found in adults are lower than those seen in children.⁽³⁾

Most pneumococcal infections are mild, but severe disease can occur.⁽⁴⁾ S. pneumoniae can cause several types of infections, including pneumonia, ear infections, sinus infections, bloodstream infections (bacteremia), and meningitis.⁽⁵⁾ Less commonly, S. pneumoniae can cause bacterial infections of the bones and joints,6 pericarditis, endocarditis, and peritonitis.⁽⁷⁾

In adults, pneumococcal pneumonia is the most common form of pneumococcal disease. The incubation period for pneumococcal pneumonia is 1 to 3 days, and the initial symptoms of chills, rigors, and fever often come on suddenly. Other symptoms include productive cough, rapid heart rate and breathing, shortness of breath, poor oxygenation, rust-colored sputum, weakness, and malaise. Headache, vomiting and nausea may also occur, although less frequently.⁽⁸⁾

Pneumococcal bacteremia without pneumonia is another form of pneumococcal disease, and symptoms include chills, fever, and a depressed level of consciousness.⁽⁹⁾ An estimated 5.000 cases of pneumococcal bacteremia occur in the United States each year.⁽¹⁰⁾

Pneumococcal meningitis accounts for more than 50% of all cases of bacterial meningitis in the United States. Symptoms of meningitis can include fever, stiff neck, irritability, vomiting, seizures, headache, sensitivity to light, and coma. Between 3.000 and 6.000 cases of pneumococcal meningitis occur each year in the United States, and approximately 22% of adults and 8% of children die.⁽¹¹⁾

In children, acute otitis media (middle ear infection) is the most common form of pneumococcal disease, and S. pneumoniae can be found in up to 55% of ear aspirates. Before the age of one, more than 60% of children have at least one middle ear infection. Otitis media results in more doctor visits than any other childhood disease.⁽¹²⁾ Symptoms of pneumococcal otitis media (middle ear infection) in children include tantrums, clicking ears, insomnia, hearing difficulties, and balance problems.⁽¹³⁾ In some children, ear infections can become chronic, resulting in recurrent use of antibiotics or surgery to insert tubes in the ears.^(14-15)

Laboratory tests of blood or other body fluids, such as cerebrospinal fluid, should be done to confirm the diagnosis of S. pneumoniae.⁽¹⁶⁾