3.7.1: Coagulase Test

OER - BIOL 2420 Laboratory Manual · LibreTexts

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    From LibreTexts, under CC BY 4.0, as the source states it; its equations are written in TeX, which the PDF shows typeset. This page at LibreTexts.

    Coagulase is an exoenzyme produced by some species within the genera Staphylococcus, including Staphylococcus aureus. Coagulase contributes to the virulence of such species by permitting the bacteria to clot blood. The enzyme interacts with the enzyme prothrombin which then converts fibrinogen to fibrin in the plasma which in turn forms the clot. It has been hypothesized that the bacteria capable of doing this are protected by the network of fibrin proteins, preventing their phagocytosis by the immune cells of the host.

    This test can assist in differentiating Staphylococcus aureus from other species of Staphylococcus such as Staphylococcus epidermidis and Staphylococcus haemolyticus.

    The coagulase test is performed using rabbit plasma in a test tube. The bacteria is added to the media and then the media is observed to determine if the plasma coagulates.

    Coagulase Test Results
    Coagulase positive Coagulase negative
    Examples:

    Staphylococcus aureus

    Staphylococcus intermedius    		 Examples:

    Staphylococcus epidermidis

    Staphylococcus haemolyticus
    Coagulase test - Top positive tube, bottom negative result.
    Coagulase test - Top culture tube shows a positive tube, bottom culture tube shows a negative result. Source: isis325, flickr, CC BY 2.0.

    This page titled 3.7.1: Coagulase Test was last modified on Sat, 25 Jul 2026 03:43:00 GMT and is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by Sherry Smith.