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 coagulase negativity usually excludes
S. aureus. However it is now known that not all S. aureus are coagulase-positive.