What is the recommended anticoagulant for body fluids that may clot sent for microbiologic examination?

• A. Heparin
• B. Sodium polyethanol sulfonate (SPS)
• C. Sodium EDTA
• D. Sodium citrate

Answer: (B)

Sodium polyanethol sulfonate (SPS) is used because it both prevents clotting and enhances the chances of recovering viable organisms from body fluids sent for culture. It acts as an anticoagulant by interfering with clot formation, allowing proper sample processing, and it also dampens certain immune activities that can kill bacteria, helping to maximize culture yield.

Other anticoagulants are less suitable for culture. Heparin can interfere with some culture tests and media, EDTA chelates divalent cations and can inhibit growth of some bacteria or affect downstream tests, and citrate is mainly used for coagulation studies rather than optimizing microbial recovery.