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Justin
Coagulase Test
~0.6 mins read
This is a laboratory procedure used to differentiate staphylococcus aureus (positive) which produces the enzyme coagulase, from Staphylococcus epidermis and S. Saprophyticus(negative) which do not produce coagulase.
Principle: coagulase is an enzyme like protein and causes plasma to clot by converting fibrinogen to fibrin.
Procedure(slide test) ;
1.place a drop of physiological saline on each end of a slide, or on 2 separate slides.
2.with the loop, emulsify a portion of the isolated colony in each drops to make 2 thick suspensions.
3.Add a drop of human or rabbit plasma to one of the suspensions, and mix gently.
4.looking for clumping of the organisms within 10seconds.
5.No plasma is added to the second suspension to differentiate any granular appearance of the organism from true coagulase clumping.
profile/7350IMG_20200427_212430.jpg
Justin
Catalase Test
~0.4 mins read
This is a laboratory procedure used to differentiate staphylococci (catalase positive) from streptococci(catalase negative).
A catalase is a common enzyme found in nearly all living organisms exposed to oxygen. It catalyzes the decomposition of water and oxygen. It is important in protecting the cell from oxidative damage.
Procedure;
1.transfer a small amount of bacteria colony into a surface of clean, dry glass slide using a loop.
2.place a drop of 3% hydrogen peroxide on the slide and mix.
3.A positive result is the rapid evolution of oxygen(within 5-10sec) as evidenced by bubbling.
4.A negative result no bubbles.
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