Pneumococcal infections are caused by the gram-positive bacteria Streptococcus pneumoniae (pneumococcus).
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 inhale infected droplets dispersed by sneezing or coughing. 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.
Certain conditions make people more likely to develop these infections, and vaccination is recommended for such people. Older people, even if healthy, tend to have more severe symptoms and complications when they get a pneumococcal infection.
Most pneumococcal infections occur in the lungs (pneumonia), middle ear (otitis media, which is common among children), or sinuses (sinusitis). Pneumonia may develop after influenza, which damages the lining of the respiratory tract.
The bacteria may also spread to and through the bloodstream (causing bacteremia). Infections may occur in the space within the tissues covering the brain and spinal cord (meningitis) or, less often, in heart valves, bones, joints, or the abdominal cavity.
Symptoms and Diagnosis
Symptoms vary depending on the site of the infection.
Often, symptoms begin suddenly. People have fever, chills, a general feeling of illness (malaise), shortness of breath, and a cough. The cough brings up sputum that becomes rust-colored.
Commonly, sharp, stabbing chest pains occur on one side. Deep breathing and coughing make the pains worse. This pain is called pleurisy.
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. However, these tests do not always enable doctors to identify the bacteria.
People have fever, headache, and a general feeling of illness (malaise). Moving the neck becomes painful and difficult, but this problem is not always obvious early in the disease. Infants may only be reluctant to eat and be irritable or sluggish.
The diagnosis 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:
These infections cause ear pain and a red, bulging eardrum or pus behind the eardrum.
The diagnosis 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.
Conjugate vaccine is the only one that works in children under 2 years old. It is routinely given to children starting at age 2 months but can be started at age 6 weeks. Three doses are given at 2-month intervals, followed by a fourth dose, usually at age 12 to 15 months (see see Sidebar 3: Vaccinating Infants and Children). Because of this vaccine, serious pneumococcal infections—pneumonia, otitis media, and meningitis—are much less common among children.
Nonconjugate polysaccharide vaccine is recommended for people who are at high risk of pneumococcal infections or complications after a pneumococcal infection. These people include the following:
The nonconjugate vaccine is effective against many more types of pneumococci than the conjugate vaccine. Thus, children at high risk, such as those with sickle cell anemia or AIDS, are given one dose of the nonconjugate vaccine at age 2 years (but at least 2 months after the last dose of conjugate vaccine), even if they have had the conjugate vaccine.
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, or vancomycin, are often used.
Last full review/revision September 2008 by Matthew E. Levison, MD