Why is Streptococcus pneumoniae so virulent?

S. pneumoniae has many virulence factors (Table ​2; Figure ​4) that allow for adherence to host cells, reduce the host’s immune system’s ability to clear the bacterium, and promote invasion of epithelial cells (17).

What is the major virulence factor of Streptococcus pneumoniae?

The polysaccharide capsule is probably the most important virulence factor of the pneumococcus. The role of the capsule in virulence stems from its antiphagocytic activity [1]. Antibody to cell wall constituents of the pneumococcus becomes attached to the surface of the organism, and in turn binds complement.

How is Streptococcus pneumoniae killed?

J Immunol. 2009 Aug 15;183(4):2602-9. doi: 10.4049/jimmunol.

Which strain of Streptococcus pneumoniae is virulent?

Streptococcus pneumoniae is a leading cause of pneumonia, meningitis, and bacteremia, estimated to cause 2 million deaths annually. The majority of pneumococcal mortality occurs in developing countries, with serotype 1 a leading cause in these areas.

What makes a pneumococci different from A streptococci?

and this test is used to differentiate Pneumococci from Streptococci. Pneumococci are oxidase and catalase test negative. They do not display an M protein like some other Streptococci. The specific characteristics of Pneumococci include bile solubility, optochin sensitivity and Quellung phenomenon or Capsule swelling reaction.

Which is the best temperature for pneumococci to grow?

16.5 CULTURAL CHARACTERISTICS Pneumococci are fastidious organisms to grow i. e. they require enriched medium (blood agar) to grow. The optimum temperature for growth is 37° C (range is 25-42° C) and pH is 7.8. Pneumococci grow better in an atmosphere with 5-10% CO 2 (culture plates kept in candle jar and incubated).

What is the lanceolate shape of pneumococcus?

One end of the Pneumococcus is broad and the other end is pointed giving it the typical lanceolate shape. The broad end of the cocci in pair is in apposition and pair of cocci is surrounded by a big capsule. The capsule is most apparent in smears made from exudates (patient sample), capsule is usually lost in culture. MICROBIOLOGY

Where do pneumococci live in the human body?

Pneumococci normally inhabit the mucosa of the upper respiratory tract which is kind of the natural habitat of these bacteria. Healthy adults are carriers (approximately 40–70 %) of Pneumococci.