Coagulase test: Difference between revisions

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.

@@ Line 1: / Line 1: @@
-* 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 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
+**[[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
+**A few species of [[coagulase-negative staphylococci]] may be positive due to membrane-bound clumping factor
-** [[S. aureus]] is negative in 15% of tests, especially MRSA, so negative results need to be confirmed with tube coagulase
+***[[Staphylococcus lugdenensis]], [[Staphylococcus schleiferi]] subsp. ''schleiferi'', [[Staphylococcus sciuri]] subsp. ''carnaticus'', and [[Staphylococcus sciuri]] subsp. ''rodentium''
-* '''Tube coagulase'''
+*'''Tube coagulase'''
-** Mix a heavy inoculum of bacteria into a tube filled with rabbit plasma
+**Checks for free coagulase
-** Positive if clot is formed within 4 hours when incubated at 37ºC
+**Mix a heavy inoculum of bacteria into a tube filled with rabbit plasma
-** A few species of [[Coagulase-negative staphylococci]] may be positive
+**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)[[CiteRef::sasaki2010mu]]
 [[Category:Diagnostics]]