Coagulase test: Difference between revisions

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* Used to differentiate [[Staphylococcus aureus]] from less pathogenic [[coagulase-negative staphylococci]]
*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)
*Tests for the ability of the organism to convert fibrinogen into fibrin (that is, to form a clot)
* '''Slide coagulase'''
*'''Slide coagulase'''
** 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
**A few species of [[coagulase-negative staphylococci]] may be positive, including [[Staphylococcus lugdenensis]] and [[Staphylococcus intermedius]]
** [[S. 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


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

Revision as of 22:19, 23 August 2020

References

  1. ^  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.