Coagulase test: Difference between revisions

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**Checks for agglutination after a drop of plasma is combined with a suspension of the bacteria on a slide
**Checks for agglutination after a drop of plasma is combined with a suspension of the bacteria on a slide
**Positive if clumping is apparent within 10 seconds or less, and no clumping is observed in saline or water
**Positive if clumping is apparent within 10 seconds or less, and no clumping is observed in saline or water
**A few species of [[coagulase-negative staphylococci]] may be positive due to membrane-bound clumping factor, including [[Staphylococcus lugdenensis]] and [[Staphylococcus intermedius]]
**A few species of [[coagulase-negative staphylococci]] may be positive due to membrane-bound clumping factor
***[[Staphylococcus lugdenensis]], [[Staphylococcus schleiferi]] subsp. ''schleiferi'', [[Staphylococcus sciuri]] subsp. ''carnaticus'', [[Staphylococcus sciuri]] subsp. ''rodentium'', and [[Staphylococcus intermedius]]
**[[Staphylococcus aureus]] is negative in 15% of tests, especially MRSA, so negative results need to be confirmed with tube coagulase
**[[Staphylococcus aureus]] is negative in 15% of tests, especially MRSA, so negative results need to be confirmed with tube coagulase
*'''Tube coagulase'''
*'''Tube coagulase'''
**Mix a heavy inoculum of bacteria into a tube filled with rabbit plasma
**Mix a heavy inoculum of bacteria into a tube filled with rabbit plasma
**Positive if clot is formed within 4 hours when incubated at 37ºC
**Positive if clot is formed within 4 hours when incubated at 37ºC
**A few species of [[Coagulase-negative staphylococci]] may be positive
**A few species of [[Coagulase-negative staphylococci]] may be positive: [[Staphylococcus intermedius]], [[Staphylococcus saccharolyticus]], and [[Staphylococcus schleiferi]]


[[Category:Diagnostics]]
[[Category:Diagnostics]]

Revision as of 22:31, 23 August 2020