blog




  • Essay / Streptococcus pneumoniae - 940

    Streptococcus pneumoniaeHistory of lifeStreptococcus pneumoniae is present throughout the world. The common host is the human body, in which it often does not cause disease, but at other times it can cause disease, including pneumonia. It also causes otitis media, bacteremia, meningitis, peritonitis and sinusitis. The route by which this organism spreads is from human to human in the form of aerosol droplets. Within the host, the nasopharynx is the primary site of pneumococcal colonization in the body. From this site, it can aspirate into the lungs, eventually spread to the bloodstream, and cross the blood-brain barrier to the meninges. Once in the blood, it can cause infections throughout the body. Symptoms of the illness include sudden cold, fever, cough, pleuritic pain, or rusty red/brown-colored sputum. Microbiological characteristicsStreptococcus pneumoniae is a Gram-positive cocci. They are usually found in pairs of cocci, or diplococci, but they can also occur in short chains or singly. When grown on blood agar, they demonstrate alpha hemolysis. They are non-mobile organisms. VirulenceVirulence is caused by the chemical composition of the capsule. There are more than 90 serotypes of S. pneumoniae, which poses great difficulties when trying to develop a vaccine against this bacteria. The capsule interferes with phagocytosis by preventing C3b opsonization of bacterial cells.DiseasesS. pneumoniae is the leading cause of pneumonia at all ages. Pneumonia due to this organism is characterized by four stages. Initially, the lung alveoli fill with a serous fluid that is thought to be stimulated by the body's cell wall. This fluid contains many organisms but few inflammatory cells... middle of paper ......for pneumonia, 6 million cases of otitis media and 60,000 cases of invasive diseases, including 3,300 cases of meningitis . Incidence in the United States has shown a geographic variation of 21 to 33 cases per 100,000 people. Interestingly, Alaska Native adults have an 8 times higher rate of disease and Alaskan infants have a 4 times higher rate than the reference American community. This statistic indicates how the organism spreads, because S. pneumoniae spreads through aerosol droplets, from person to person. The fact that Alaskans must stay indoors and live in crowded conditions and poorly ventilated homes increases the transmission and therefore the incidence of S. pneumoniae in this region. Sources cited: http://www.dhfs.state.wi.us/healthtips /BCD/StrepPneumo.htmhttp://www2.cdc.gov/ncidod/aip/Strep/strep.asphttp://www.bact.wisc .edu/Bact330/lecturespneumo