Pneumococcal Bacteria

Pneumococcal Bacteria


Pneumococcus Meaning

  • Pneumococcus is a partner of the upper respiratory tract.
  • Pneumococci essential pathogen of pneumonia and oddities media in children.
  • Pneumococci is reclassified into the streptococcus pneumoniae.


Pneumococcus Morphology

  • It is a small, slightly elongated, gram positive cocci that is arranged in pair.
  • Each coccus consist two ends, one end is rounded or broad and other is pointed.
  • Each pair is enclosed by the capsule.
  • Pneumococcus is non motile and non sporing.


Pneumococcus Culture 

  • Pneumococci are aerobs and facultative anaerobes.
  • Pneumococci growth require 37° C temperature and 7.8 PH.
  • On the blood agar, the colonies are small, dome shaped after 18 hour incubation.
  • On the prolonged incubation, colonies flat with raised edge.
  • Pneumococci produce the uniform turbidity in the liquid medium.

Pneumococcus Biochemical reactions

  • Pneumococci ferment several sugars with the production of acid.
  • Generally, pneumococci are soluble in the bile.
  • Pneumococci is the catalase and oxidase negative.
  • Bile solubility test is a essential test to differentiate the pneumococcus from the streptococci.


Pneumococcal resistance mechanism

  • Pneumococci are more sensitive to the usual antiseptics.
  • Pneumococci are destroyed at 52° C temperature for 15 minutes.


Pneumococcal Antigenic structure

  • The most important antigen of pneumococcus – is capsular polysaccharides.
  • Other antigens are – M protein and cell wall carbohydrate.


  1. Capsular polysaccharide – It is a specific pneumococci that is classified based upon the capsular polysaccharide nature.


  1. M protein – It is another type of pneumococci that is associated with antibody and virulence to M protein.


  1. Cell wall carbohydrate – It is a specific carbohydrate Antigen that called C – substance.
  • It is precipitate due to abnormal protein and occur in the acute phase of pneumonia and disappear during convalescence.
  • C – Substance also occur in the patient blood with some other disease, is called C – reactive protein (CRD).


Pneumococcus Pathogenesis

  • Streptococcus pneumoniae is the most common bacteria which is causing pneumonia (both lobar and bronchopneumonia).
  • It is second most important cause of pyogenic meningitis.
  • This type disease most commonly occur in the children.


Pneumococcus Laboratory diagnosis

  1. Specimens – 

  • CSF, sputum, blood, pleural exudate, etc.
  • For pneumococci septicaemia, blood culture is useful.
  1. Collection and transport

  • All sample should be collected in the sterile container under the aseptic techniques and transport immediately in the lab.
  1. Direct microscopic – Gram staining of smear demonstrate the large number of polymorphs and typical organism.
  1. Culture – The sample should be incubated on the blood agar.
  • The sample also inoculated at 37° C temperature for 24 hours in the presence of CO2.
  1. Biochemical reaction – Biochemical test describe the steps to cocas pneumoniae is differentiate from the streptococcus viridans.
  • The biochemical test is insulin fermentation and bile solubility test.

Animal pathogenicity test 

  • The heart blood and peritoneal exudate of pneumococci.

Pneumococcus Treatment

  • Antibiotic of choice – Parenteral penicillin.


  • Reference – Textbook of microbiology 5th edition, By DR. C. P. Baveja.
  • Page no. 196 – 198.
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