In the lab, SPS typically refers to Sodium Polyanethole Sulfonate, an anticoagulant commonly used in blood culture collection.
Here's a more detailed explanation:
-
Purpose: SPS is primarily used in blood culture vials to prevent blood from clotting and to inhibit the activity of certain components of the immune system that could kill or inhibit the growth of bacteria. This allows for the detection and identification of bacteria in the bloodstream, a condition known as bacteremia or sepsis.
-
Mechanism of Action:
- Anticoagulant: SPS acts as an anticoagulant by binding to calcium ions, which are essential for the coagulation cascade.
- Inhibition of Complement and Phagocytosis: SPS also inhibits the complement system and phagocytosis by white blood cells. These are innate immune mechanisms that can kill bacteria in the blood sample, potentially leading to false-negative results in blood cultures. SPS helps to neutralize these effects, maximizing the chances of bacterial growth and detection.
-
Use in Blood Cultures: SPS is a critical component of blood culture media. When blood is drawn for culture, it is injected into vials containing SPS and other nutrients that support bacterial growth. The SPS prevents the blood from clotting and inhibits the host's defenses, allowing any bacteria present in the blood to multiply to detectable levels.
-
Example: In a hospital setting, if a patient presents with a fever and suspected sepsis, blood cultures will be ordered. The blood will be drawn into special bottles containing SPS. These bottles are then incubated in a laboratory, and if bacteria grow, they can be identified, allowing the physician to prescribe the appropriate antibiotic.
In summary, SPS (Sodium Polyanethole Sulfonate) plays a vital role in laboratory blood cultures by preventing coagulation and neutralizing the activity of certain immune factors, ultimately enhancing the detection of bacteria in blood samples.
