Streptococcus pneumoniae (S. pneumoniae) related knowledge
Streptococcus pneumoniae (S. pneumoniae) is a gram-positive bacterium (1) first isolated from the saliva of a patient with rabies by Pasteur in 1881. The chemical structure and antigenicity of the pneumococcal capsular polysaccharide and its association with virulence and its role in human disease were explained over the period of 1915 to 1945. The bacteria are lancet-shaped anaerobic organisms spreading by direct person-to-person contact via respiratory droplets and causing serious disease in humans: The 10 most common serotypes are estimated to account for about 62% of invasive disease worldwide (2). S. Pneumoniae colonizes upper respiratory tract tissues causing severe pneumonia and mild/acute earache/otitis. Pneumococci cause 13% to 19% of all cases of bacterial meningitis in the United States (4). One-fourth of patients with pneumococcal meningitis also have pneumonia. Clinical symptoms are generally similar to those of other forms of purulent bacterial meningitis and include headache, lethargy, vomiting, irritability, fever, nuchal rigidity, cranial signs, seizures and coma. The case-fatality of pneumococcal meningitis is about 30% but can be as high as 80% among the elderly. Bacterial pneumonia accounts for 12-16% of invasive pneumococcal disease among children aged 2 years and younger whereas S. Pneumoniae has become the leading cause of bacterial meningitis among children younger than 5 years of age in the United States. Antibiotic treatment is efficient even if more penicillin-resistant strains have been identified (5). Several vaccines are available with variable efficiency depending on patient age or whether patients are developing some chronic illness or immunodeficiency. Nevertheless, vaccines have been demonstrated to provide protection against pneumococcal pneumonia (6).
1. AlonsoDeVelasco, E., Verheul,A.F.,Verhoen, J, Snippe, H. Streptococcus pneumoniae: virulence factors, pathogenesis, and vaccines. Microbiological Reviews, 59 (4), 591-603, 1995.
2. CDC. Updated recommendations for preventionof invasive pneumococcal disease among adults using the 23-valent pneumococcal polysaccharide vaccine (PPSV23). MMWR, 59 (34) : 1102-1106, 2010.
3. Kadioglu, A., Weiser, J.N., Paton, J.C., and Andrew, P.W. The role of Streptococcus pneumoniae virulence factors in host respiratory colonization and disease. Nature Reviews, Microbiology, 6 (4) doi: 10.1038/nrmicro1871, 2008. 6
4. Robinson, K.A., Baughman, W., Rothrock, G. Epidemiology of invasive Streptococcus pneumoniae infections in the United States, 1995-1998. Opportunities for prevention in the conjugate vaccine era. JAMA, 285 : 1729-1735, 2001.
5. Whitney, C.G., Farley, M.M., Hadler, J. et al. Increasing prevalence of multidrug-resistant Streptococcus pneumoniae in the United States. N. Engl. J. Med., 343 : 1917-1924, 2000.
6. Tsai, C.J., Griffin, M.R., Nuorti, J.P. et al. Changing epidemiology of pneumococcal meningitis after the introduction of pneumococcal conjugate vaccine in the United States. Clin. Infect. Dis., 46 : 1664-1672, 2008.