page_title: Coagulase
hierarchical_section_title: Coagulase
caption_attribution_description: Bacterial cells of Staphylococcus aureus, which is one of the causal agents of mastitis in dairy cows. Its large capsule protects the organism from attack by the cow's immunological defenses. This image was taken at 50,000X magnification on a Transmission Electron Microscope of a heavy-metal coated replica of a freeze dried sample, (TEM) Plate #.9514. Sourced from Plate #.9513's information. 日本語: 乳牛における乳腺炎の一因である黄色ブドウ球菌の細菌性細胞
context_page_description: Coagulase is a protein enzyme produced by several microorganisms that enables the conversion of fibrinogen to fibrin. In the laboratory, it is used to distinguish between different types of Staphylococcus isolates. Importantly, S. aureus is generally coagulase-positive, meaning that a positive coagulase test would indicate the presence of S. aureus. A negative coagulase test would instead show the presence of coagulase negative organisms such as S. epidermidis or S. saprophyticus. However it is now known that not all S. aureus are coagulase-positive.
  It is also produced by Yersinia pestis.
  Coagulase reacts with prothrombin in the blood. The resulting complex is called staphylothrombin, which enables the enzyme to act as a protease to convert fibrinogen, a plasma protein produced by the liver, to fibrin. This results in clotting of the blood. Coagulase is tightly bound to the surface of the bacterium S. aureus and can coat its surface with fibrin upon contact with blood. The fibrin clot may protect the bacterium from phagocytosis and isolate it from other defenses of the host. The fibrin coat can therefore make the bacteria more virulent.
context_section_description: Coagulase is a protein enzyme produced by several microorganisms that enables the  conversion of fibrinogen to fibrin. In the laboratory, it is used to distinguish between different types of Staphylococcus isolates. Importantly, S. aureus is generally coagulase-positive, meaning that a positive coagulase test would indicate the presence of S. aureus. A negative coagulase test would instead show the presence of coagulase negative organisms such as S. epidermidis or S. saprophyticus. However it is now known that not all S. aureus are coagulase-positive.
  It is also produced by Yersinia pestis.
  Coagulase reacts with prothrombin in the blood. The resulting complex is called staphylothrombin, which enables the enzyme to act as a protease to convert fibrinogen, a plasma protein produced by the liver, to fibrin. This results in clotting of the blood. Coagulase is tightly bound to the surface of the bacterium S. aureus and can coat its surface with fibrin upon contact with blood. The fibrin clot may protect the bacterium from phagocytosis and isolate it from other defenses of the host. The fibrin coat can therefore make the bacteria more virulent. Bound coagulase is part of the larger family of MSCRAMM adhesin proteins.
caption: (TEM cryomicroscopy technique) - S. aureus forms a fibrin capsule that protects it from the immune system of cattle
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