Cell Structure

Cell Structure

source: http://images.fineartamerica.com/images-medium-large/2-streptococcus-pneumoniae-bacteria-roger-harris.jpg

Streptococcus pneumoniae have a round coccus shape, and are often found as diplococci as seen in the picture. They have a polysaccharide capsule which protects them from immune system detection. Streptococcus pneumoniae have pili that help them adhere to the respiratory tract, and prevent them from being expelled by coughing.

Source: https://microbewiki.kenyon.edu/index.php/Streptococcus_pneumoniae

Where is Streptococcus pneumoniae found?

https://edc2.healthtap.com/ht-staging/user_answer/reference_image/7450/large/respiratory_system.jpeg?1386670508

Streptococcus pneumoniae is found in the upper respiratory system of mammals as a part of the normal flora (2).

Host Interactions

When found in low densities, Streptococcus pneumoniae lives unnoticed in its host. However when found at larger densities, it causes pneumonia (1). Pneumonia is characterized by coughing, green-yellow phlegm, fever, and chest pain (1). Streptococcus pneumoniae causes Pneumonia by initiating a cytokine reaction in the lungs, which leads to the symptoms of Pneumonia. They are able to infect hosts due to various factors.

1.     The bacteria have long pili that enable it to attach to the epithelial tissue of the lungs and to resist being expelled by coughing (1).

2.     It contains a polysaccharide capsule that helps Streptococcus pneumoniae evade phagocytosis by immune cells (2).

Fun Fact: Streptococcus pneumoniae with a polysaccharide capsule are 100,000 times more virulent than strains without one! (1).

3.     Streptococcus pneumoniae contain five PBPs (penicillin binding proteins) that allow it to be penicillin resistant (2).

Phylogeny and Taxonomy

Bacteria-Firmicutes-Bacilli-Lactobacillales-Streptoccaceae-Streptococcus

References

(1) "Streptococcus pneumoniae." - MicrobeWiki. Ed. Kenyon College. Kenyon College, 29 Apr. 2011. Web. 21 Nov. 2014. <https://microbewiki.kenyon.edu/index.php/Streptococcus_pneumoniae>.

(2) Todar, Kenneth, PhD. "Streptococcus pneumoniae and Pneumococcal Pneumonia." Streptococcus pneumoniae and Pneumococcal Pneumonia. N.p., n.d. Web. 21 Nov. 2014. <http://textbookofbacteriology.net/S.pneumoniae.html>.

History, Culture Conditions, and Gram Staining

Culture Conditions

·      Requires choline and reducing agents in media.

·      Facultative anaerobe

·      Grows best at a pH of 7.8.

·      Optimal growth temperature 30-35C

·      Grows best on a blood agar plate.

·      Needs vitamin B complex, 7-10 amino acids, adenine, guanine, and uracil.

Source: http://www.biomedcentral.com/1471-2180/5/34

Streptococcus pneumoniae is gram-positive

source: http://web.uconn.edu/mcbstaff/graf/Student%20presentations/Streptococcuspneu/Spneumo.jpg

Here the Streptococcus pneumoniae are shown as the dark cocci in the picture from a gram stain.

History

1881: Pasteur isolates Streptococcus pneumoniae for the first time.

1884: The discovery of Gram staining allows S. pneumoniae to be identified from other causes of pneumonia.

1940: By this time 80 plus serotypes of pneumococci had been described.

1960s: Many patients died despite receiving penicillin to treat S. pneumoniae infections.

1977: The first US pneumococcal vaccine is licensed.

Source: http://www.cdc.gov/vaccines/pubs/pinkbook/downloads/pneumo.pdf

Metabolic Lifestyle

Metabolic Lifestyle of Streptococcus pneumoniae

(2) http://www.streppneumoniae.com/figure1.asp 

·      Streptococcus pneumoniae is a Chemoorganoheterotroph.

o   It ferments glucose into lactic acid using lactate as an electron acceptor (3).

·      It has an extracellular enzyme system which lets it metabolize polysaccharides and hexosamines (1).

Interesting Aspects of Streptococcus pneumoniae

http://textbookofbacteriology.net/S.pneumoniae.html

S. pneumoniae cultured on a blood agar plate (3).

S. pneumoniae does not make its own catalase, so it must be grown on a medium that includes catalase e.g. blood (3). Without catalase, the bacteria will produce too much hydrogen peroxide (3).

References 

(1) "Streptococcus pneumoniae." - MicrobeWiki. Ed. Kenyon College. Kenyon College, 29 Apr. 2011. Web. 22 Oct. 2014. <https://microbewiki.kenyon.edu/index.php/Streptococcus_pneumoniae>.

(2) "Streptococcus pneumoniae Metabolism." Streptococcus pneumoniae Metabolism. American Society for Microbiology, 2001. Web. 24 Oct. 2014. <http://www.streppneumoniae.com/figure1.asp>.

(3) Todar, Kenneth, PhD. "Streptococcus pneumoniae and Pneumococcal Pneumonia." Streptococcus pneumoniae and Pneumococcal Pneumonia. N.p., n.d. Web. 22 Oct. 2014. <http://textbookofbacteriology.net/S.pneumoniae.html>.