Symptoms and Causative Agent
Streptococcus pneumoniae bacteria, also called pneumococcal bacteria, pneumococci (plural), and pneumococcus (singular), are one of the leading causes of illness in young children. At least 90 types of pneumococcal bacteria are known to exist. As the name implies, they can cause pneumonia; however, these bacteria also can cause bloodstream infections (bacteremia), meningitis, sinusitis, and middle ear infection, among other illnesses. Collectively, the different illnesses caused by Streptococcus pneumoniae are referred to as pneumococcal disease.
Symptoms of pneumococcal disease vary based on the specific illness the bacteria have caused. Pneumococcal pneumonia symptoms include fever, chest pain, cough, and shortness of breath. When pneumococci infect normally sterile locations, so-called invasive pneumococcal disease may result. The two major types of invasive pneumococcal disease are bacteremia and meningitis (infection of the fluids and tissues surrounding the brain and/or spinal cord). Pneumococcal meningitis symptoms include fever, headache, stiffness in the neck, light sensitivity, and disorientation. Pneumococcal bacteremia may complicate localized infections such as pneumonia and is commonly associated with high fever and shaking chills.
Invasive pneumococcal disease can be fatal; survivors of meningitis may have permanent injury, including brain damage, seizures, or hearing loss.
Many people are colonized by Streptococcus pneumoniae bacteria without becoming ill. The bacteria are present in the noses or throats of many healthy individuals (5-10% of adults without children are carriers, as are 27-58% of school students) and can be spread to others via coughing or sneezing. People who are ill with pneumococcal disease can spread the bacteria in the same way as carriers can.
Individuals with sickle cell disease, certain immune deficiencies, or chronic renal disease, and those taking immunosuppressive drugs or using cochlear implants, are at an increased risk for pneumococcal infection. Cigarette smoking also increases the risk of invasive pneumococcal disease.
Treatment and Care
Antibiotics are used to treat pneumococcal disease, but some strains of the bacteria have developed resistance to some of the drugs used against them. Drug resistance can complicate treatment and increase the length of hospital stays.
Invasive pneumococcal disease and pneumococcal pneumonia can be extremely serious and often require hospitalization.
Each year in the United States, pneumococcal bacteria cause more than 4,800 cases of invasive pneumococcal disease in children younger than five years of age. Among this group, about 5% die from the infection. Of those who survive, some are left with permanent injury.
Pneumococcal bacteremia (bloodstream infection) cases total more than 50,000 each year in the United States (bacteremia occurs in approximately 25% of all pneumococcal pneumonia cases). The case fatality rate for those with pneumonia complicated by bacteremia is approximately 20%, but may be as high as 60% for elderly patients. Pneumococcal meningitis cases total about 3,000 each year in the United States, and the mortality rate is 10-30%.
Pneumococcal pneumonia causes an estimated 175,000 hospitalizations each year in the United States, and has a case fatality rate of 5-7% (in the elderly this figure is higher). Pneumococcus is the cause of up to 36% of community-acquired pneumonia cases, and 50% of community-acquired cases that require hospitalization.
Available Vaccines and Vaccination Campaigns
A pneumococcal vaccine that protected against 14 different strains was licensed in 1977, and expanded to protect against 23 strains in 1983. This vaccine is a polysaccharide vaccine called PPSV23 (brand name Pneumovax 23, manufactured by Merck). However, it is most effective in adults, and does not consistently generate immunity in children younger than two years old. A separate vaccine for children called PCV7 was licensed in 2000. PCV7 is a conjugate vaccine (see our article, Different Types of Vaccines, for more on how these vaccines are made); it was expanded to include protection against 13 strains in 2010, and renamed PCV13 (brand name Prevnar 13, manufactured by Pfizer). PCV13 protects against the bacterial strains responsible for the most severe childhood pneumococcal infections.
PCV7 was added to the recommended childhood vaccination schedule in 2000 (PCV13 replaced it on the schedule in 2010). Since the initial recommendation, invasive pneumococcal disease in children has dropped by nearly 80% in the United States.
U.S. Vaccination Recommendations
Pneumococcal vaccination via PCV13 is included on the U.S. childhood immunization schedule for all children younger than five years of age. Additional protection via the polysaccharide vaccine (PPSV23) is recommended for children with certain underlying medical conditions. The PPSV23 vaccine is also recommended for adults with certain risk factors for pneumococcal disease up to age 65, including asthma and cigarette smoking
Since 1984, the Advisory Committee on Immunization Practices (ACIP) has recommended that individuals age 65 and older should receive pneumococcal polysaccharide vaccine (PPSV). In 2014, the Advisory Committee on Immunization Practices recommended that adults age 65 and older also receive pneumococcal conjugate vaccine (PCV). Therefore, at age 65, adults who have never received pneumococcal vaccine should receive a single dose of PCV13 followed 6-12 months later by a dose of PPSV23.