Coagulase test: Difference between revisions
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*Tests for the ability of the organism to convert fibrinogen into fibrin (that is, to form a clot) |
*Tests for the ability of the organism to convert fibrinogen into fibrin (that is, to form a clot) |
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*'''Slide coagulase''' |
*'''Slide coagulase''' |
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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 from bound coagulase and clumping factors 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 |
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**[[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 |
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***[[Staphylococcus lugdenensis]], [[Staphylococcus schleiferi]] subsp. ''schleiferi'', [[Staphylococcus sciuri]] subsp. ''carnaticus'', and [[Staphylococcus sciuri]] subsp. ''rodentium'' |
***[[Staphylococcus lugdenensis]], [[Staphylococcus schleiferi]] subsp. ''schleiferi'', [[Staphylococcus sciuri]] subsp. ''carnaticus'', and [[Staphylococcus sciuri]] subsp. ''rodentium'' |
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*'''Tube coagulase''' |
*'''Tube coagulase''' |
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| + | **Checks for free coagulase |
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**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 |
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**Positive if clot is formed within 4 hours when incubated at 37ºC |
**Positive if clot is formed within 4 hours when incubated at 37ºC |
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Latest revision as of 19:12, 23 August 2020
- Used to differentiate Staphylococcus aureus from less pathogenic coagulase-negative staphylococci
- Tests for the ability of the organism to convert fibrinogen into fibrin (that is, to form a clot)
- Slide coagulase
- Checks for agglutination from bound coagulase and clumping factors 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
- Staphylococcus aureus is negative in 15% of tests, especially MRSA, so negative results need to be confirmed with tube coagulase
- 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, and Staphylococcus sciuri subsp. rodentium
- Tube coagulase
- Checks for free coagulase
- 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
- A short list of animal-associated staphylococci are also coagulase-positive: Staphylococcus intermedius (dogs), Staphylococcus schleiferi subsp. coagulans, Staphylococcus hyicus, Staphylococcus lutrae, Staphylococcus delphini (dolphins), and Staphylococcus pseudintermedius (dogs)1
References
- ^ Takashi Sasaki, Sae Tsubakishita, Yoshikazu Tanaka, Arihito Sakusabe, Masayuki Ohtsuka, Shintaro Hirotaki, Tetsuji Kawakami, Tsuneo Fukata, Keiichi Hiramatsu. Multiplex-PCR Method for Species Identification of Coagulase-Positive Staphylococci. Journal of Clinical Microbiology. 2010;48(3):765-769. doi:10.1128/jcm.01232-09.
