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STREPTOCOCCUS. 411 , Lab 5 Amany Niazy. Streptococci. + ve. - ve. All are Gram Positive Cocci arranged in chains (short or long) All are Catalase - ve. Gram Stain. Staphylococci. streptococci. Culture. Fastidious organism  no growth on NA Grows well on BAP

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STREPTOCOCCUS

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STREPTOCOCCUS

411 , Lab 5

AmanyNiazy


Streptococci

+ ve

- ve

All are Gram Positive Cocci arranged in chains (short or long)

All are Catalase -ve


Gram Stain

Staphylococci

streptococci


Culture

Fastidious organism  no growth on NA

Grows well on BAP

Facultative anaerobe

Grow at 37C need 24 to 48 hour .


Streptococcus Classification

  • Alpha hemolytic

    • S. viridans

    • S. pneumoniae

  • Beta hemolytic:

    • Group A, B, C, G & D

      Lancefield grouping according to antigens in their cell wall

  • Non-hemolytic:

    • Enterococcus (formaly known as Group D


Alpha Hemolytic Streptococci

  • Give alpha hemolysis on BAP.

  • It Can be divided in to 2:

    • Viridans group

    • S.pneumoniae


Streptococcus viridans

s. pneumoniae


S. PNEUMONIAE

Viridans Streptococci

  • Alpha haemolysis

  • Pin point colonies

  • Optochin resistant

  • Bile Solubility  -ve

  • Part of normal flora of upper respiratory and GI

  • Alpha haemolysis

  • Ring form colonies

  • Tanslucent or mucoid

  • Optochin sensitive

  • Sile solubility  +ve

  • Not part of NF

Not Capsulated

Flattened with raised edges

Capsulated


Viridans Streptococci

S. PNEUMONIAE

  • GPS in chains

  • GPC elongated (Lanceolated) diplococci


1. Optochin Test

Always don on a BAP.

On the primary culture of isolation plate before incubation

Ethylhydrocupreine hydrochloride.

Zone of inhibition of 14 mm or more  sensitive S. pneumoniae

No zone of inhibition S.viridans


Optochin Disk


.Bile Solubility Test

  • To test if colonies are lysed by bile salt (such as desoxycholate) or not.

  • There are 2 ways to do the test :

    • In a tube

    • On plate


Bile Solubility in Tube

  • 2 ml of saline in a tube

  • Emulsify several colonies of test organism in it

  • Divide organism suspension in 2 tubes

  • Add 2 drops of bile salt to one tube and 2 drops of sterile distilled water to the other.

  • Leave 10-25 mn at RT


Bile Solubility on Plate

  • Add drop of bile salt to specified part of plate

  • Incubate at 37C for 10 - 30 min

  • Colony disappear  +ve

  • Colony stay  -ve


Rapid Detection of S. pneumoniae

Rapid latex and coagglutination tests are available to detect capsular pneumococcal antigen in CSF or other sterile body fluids.


Sensitivity Testing of S. pneumoniae


Thank You


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