Coagulase Test

Rehydrate with 10 mL of sterile water previously heated to 37 °C. Dispense into tubes, 0.3 mL each.

After that, inoculate with 0.1 mL of a previous pure culture in BHI Broth (formulated according to ISO), or directly with a loop from an isolated colony.

Incubate at 37 °C and analyze the coagulation after 30 minutes, 1, 4 and 6 hours (up to 24 hours). The presence of S. aureus (and other coagulase-positive staphylococci) is evident because of a solidification of the medium (coagulase transforms prothrombin into staphylothrombin, which combines with the fibrinogen in the medium, and they form fibrin).

The presence of trypsin in the plasma may invert positive reactions when readings are done late.

The rehydrated plasma will remain stable for 30 days if stored at 4 °C.

Rehydrate with 10 mL of sterile water previously heated to 37 °C.

Physical/chemical control

Microbiological control

Reconstitute 1 vial as indicated in Composition; shake and dissolve completely.

Prepare a suspension from pure culture.

Analytical methodology according to ISO 11133:2014/Amd 1:2018; A2:2020.

Incubation at 37 °C, reading between 12 and 18 h.

Microbiological control according to ISO 11133:2014/Amd 1:2018; A2:2020.

Sterility control

Add 5 mL of the sample to 100 mL of TSB and to 100 mL of Thioglycollate.

Incubation 48 hours at 30-35 °C and 48 hours at 20-25 °C: NO GROWTH.

• VANDERZANT, C. and D.F. SPLITTSTOESSER (1992) Compendium of Methods for the Microbiological Examination of Foods. 3rd. Ed. APHA. Washington.
• ISO 6888-1:1999 Microbiology of food and animal feeding stuffs. Horizontal method for the enumeration of coagulase-positive staphylococci.
• ISO 11133:2014/Amd 1:2018/Amd 2:2020. Microbiology of food, animal feed and water. Preparation, production, storage and performance testing of culture media.