SLIDE COAGULASE TEST

 

AIM:

          To identify whether the organism contains the Clumping factor or bound coagulase.

PRINCIPLE:

          Bound coagulase or clumping factor is a membrane bound heat stable protein molecule present on the cell wall of certain bacteria’s which has the capacity to form clot when it comes in contact with the plasma.

          If the organism produce the clumping factor it will directly reacts with the fibrinogen in the plasma and converts it into fibrin to form clot.

 

          Clumping factor  +   Fibrinogen -----------------> Fibrin (Clot)

             (in bacteria)          (in Plasma)

 

REAGENT:

          Rabbit or Human plasma with EDTA

PROCEDURE:

1.    Take a clean glass slide and mark the slide for Positive control, Test and Negative control respectively.

2.    Add a drop of physiological saline in each and emulsify the respective culture organisms in the saline.

3.    Now add 1 or 2 drops of rabbit or human plasma to PC, Test and NC.

4.    Mix and gently rock the slide for 5-10 secs and observe for clumping.

INTERPRETATION:

          Positive control (ATCC 25923 S.aureus) – coarse clumping is observed within 10 secs.

          Negative control (ATCC 12228 S.epidermidis) – No clumping is observed.

          Test – Coarse clumping is observed within 10 secs.

EXAMPLES:

          Slide coagulase positive – S.aureus, S.hyicus, S.intermedius.

          Slide coagulase negative – S.delphini.

NOTE:

·       It is not a confirmational test, so irrespective of the results positive/negative, it should be confirmed with a Tube coagulase test.

·       Capsulated strains shows negative reaction.