🧪 Tube Coagulase Test for Staphylococcus aureus The tube coagulase test is the gold standard method for detecting free coagulase produced by Staphylococcus aureus. 🔬 How is the tube test performed? 1️⃣ A small amount of the bacterial colony is mixed with plasma (usually rabbit plasma) in a test tube. 2️⃣ The tube is incubated at 35–37°C. 3️⃣ The tube is checked at 4 hours; if negative, incubation can continue up to 24 hours. 🧫 Result interpretation: ✅ Positive: formation of a stable clot that