Streptococcus Pneumonia

Student Name: Hassan Mohammad AL-Shehri

ID#2051040006

Streptococcus Pneumoniae Streptococcus pneumoniae, or pneumococcus, is a Gram-positive, alpha-hemolytic diplococcus bacterium and a member of the genus Streptococcus. Despite the name, the organism causes many types of infection other than pneumonia, including acute sinusitis, otitis media, meningitis, osteomyelitis, septic arthritis, endocarditis, peritonitis, pericarditis, cellulitis, and brain abscess.

Pathogenesis S. pneumoniae is normally found in the nasopharynx of 5-10% of healthy adults, and 2040% of healthy children. It can be found in higher amounts in certain environments, especially those where people are spending a great deal of time in close proximity to each other. This normal colonization can become infection if the organisms are carried into areas such as the Eustachian tube or nasal sinuses where it can cause otitis media and sinusitis, respectively. Pneumonia occurs if the organisms are inhaled into the lungs and not cleared.

Virulence Factors • • • • • • •

Polysaccharide capsule: prevents phagocytosis by host immune cells Pneumolysin: kDa protein that can cause lysis of host cells and activate complement. Autolysin: activation of this protein lyses the bacteria releasing its internal contents. Hydrogen peroxide: can cause apoptosis in neuronal cells during meningitis. Pili Choline binding protein A: an adhesion that can interact with carbohydrates on the cell surface of pulmonary epithelial cells Protective Antigen: can inhibit complement-mediated opsonization of pneumococci.

Treatment S. pneumoniae were susceptible to penicillin, but there has been an increasing prevalence of penicillin resistance, especially in areas of high antibiotic use. Some strains may also be resistant to cephalosporins, macrolides (such as erythromycin), tetracycline, clindamycin and the quinolones. Penicillin-resistant strains are more likely to be resistant to other antibiotics. Most isolates remain susceptible to vancomycin.