Coagulase Test: Click Here to View Images
The coagulase test is used to differentiate S. aureus from other
Staphylococci species. Coagulase is an enzyme produced by
Staphylococcus aureus that converts fibrinogen to fibrin. S. aureus will
coagulate rabbit plasma when incubated in its presence.
Tips for Success:
Weakly coagulase positive strains may require overnight incubation for a
positive result to be observed. Always run positive and negative controls
from known cultures. Be sure to inoculate the unknown and control tubes
with approximately the same amount of inoculum. Refrigerate the
reconstituted rabbit plasma when not in use.
Procedure:
The coagulase test is used to differentiate S. aureus from other
Staphylococci species. Coagulase is an enzyme produced by
Staphylococcus aureus that converts fibrinogen to fibrin. S. aureus will
coagulate rabbit plasma when incubated in its presence.
Tips for Success:
Weakly coagulase positive strains may require overnight incubation for a
positive result to be observed. Always run positive and negative controls
from known cultures. Be sure to inoculate the unknown and control tubes
with approximately the same amount of inoculum. Refrigerate the
reconstituted rabbit plasma when not in use.
Procedure:
- Add 0.5 mL reconstituted lyophilized rabbit coagulase plasma with
EDTA to a sterile 13 x 100mm tube - Touch an isolated colony with an inoculating loop
- Place the loop, carrying some of the isolate, into the tube containing
the rabbit plasma, and mix thoroughly. - Incubate the tube at 35 deg C for 6 hours
- Observe the tube for the presence of clotting.
- If no clotting is observed, incubate for 24 hours and observe again.
- The reaction is positive if clotting is present. (The plasma will gel to
a viscosity where it will not flow down the tube when tilted at a 45
deg angle.)
| Coagulase Procedure For The Identification of Bacteria |
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