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Streptococcus pneumoniae Disease
Clinical Features Pneumonia, bacteremia, otitis media, meningitis, sinusitis, peritonitis and arthritis. Etiologic Agent Streptococcus pneumoniae. More than 90 serotypes exist; of strains causing invasive disease, 88% are serotypes included in the 23-valent polysaccharide vaccine. Before the new pneumococcal conjugate vaccine was introduced in 2001, over 80% of invasive isolates in children <5 years old were included in the 7-valent vaccine. Incidence Until 2000, S. pneumoniae infections caused 100,000-135,000 hospitalizations for pneumonia, 6 million cases of otitis media, and 60,000 cases of invasive disease, including 3300 cases of meningitis. Incidence of sterile-site infections showed geographic variation from 21 to 33 cases per 100,000 population. Disease figures are now changing due to conjugate vaccine introduction.; in 2002, the rate of invasive disease was 13 cases per 100,000 in the United States.
Sequelae Death occurs in 14% of hospitalized adults with invasive disease. Neurologic sequelae and/or learning disabilities can occur in meningitis patients. Hearing impairment can result from recurrent otitis media. Transmission Person to person. Risk Groups Persons at higher risk for infection are the elderly, children under 2 years old, blacks, American Indians and Alaska Natives, children who attend group day care centers, and persons with underlying medical conditions including HIV infection and sickle-cell disease. Surveillance Active, population-based surveillance is conducted in nine states (total population: 25 million). Reporting of drug-resistant S. pneumoniae and all invasive disease in children <5 years old has been mandated in several states. A nationwide system tracks invasive disease occurring in children <5 years who have been vaccinated. Trends The incidence among young adults and young children is decreasing, due to improved HIV therapy and to use of the new conjugate vaccine for children. Outbreaks have occurred in institutional settings and child care centers. In the United States, ß-lactam resistance is common and prevalence of strains resistant to multiple classes of drugs is increasing. Challenges Supplies of pneumococcal conjugate vaccine are inadequate. The 23-valent polysaccharide vaccine is underused. Sensitive, rapid diagnostic tests are not available for many types of pneumococcal infections, although a new urinary antigen test may be useful in adults. Widespread overuse of antibiotics contributes to emerging drug resistance. Opportunities Ability to prevent infections could improve through expanded use of 23-valent polysaccharide vaccine among adults and through use of the conjugate vaccine for infants and young children. Campaigns for judicious use of antibiotics along with the new vaccine may slow or reverse emerging drug resistance. December 2003