Rapid Test Screens for Bacterial Contamination of Platelets

It is intended to supplement current quality control testing methods used by blood establishments following collection of platelets using an automated instrument.

The test consists of a disposable plastic cartridge that can be stored at room temperature and three dropper bottle sample pretreatment reagents. The platelet PGD test procedure involves pre-treating a 500-µl-platelet sample and applying it to the sample well on the test cartridge. Within approximately 20 minutes of sample addition, a pink-colored bar will appear in one of the two reading windows on the test cartridge if either Gram-positive or Gram-negative bacteria are detected in the sample above the cut-off level of the assay. Negative samples show no color bar in the read windows.

Platelets are used to prevent or treat bleeding in individuals undergoing chemotherapy for cancer, after major trauma, during or after surgery, and in individuals who do not produce platelets. Patients who are transfused with platelets contaminated with bacteria are at risk of developing a serious and potentially life-threatening infection of the blood stream known as septicemia. Septicemia must be treated quickly to prevent the infection from spreading to the heart and lungs.

Bacterial contamination of platelets is the leading infectious cause of transfusion-related patient fatalities. The risk of a patient receiving a transfusion contaminated with bacteria is 1 in 5,000--far greater than the risk of transmitting hepatitis C virus (1 in 1.6 million) or human immunodeficiency virus (HIV) (1 in 1.9 million). To reduce the risk of transfusing contaminated platelets, blood centers culture samples of the platelets 24 hours after the donation. The culture is read within the next 24 hours (within 48 hours after the donation), and contaminated units are discarded. However, there is a possibility that the number of bacteria present at the time of culture may be so low that bacteria is not detected due to sampling limitations.

Developed by Verax Biomedical (Worcester, MA, USA), the Pan Genera detection (PGD) test system is less sensitive than standard cultures, but is performed later in storage when bacteria, if present, have multiplied, and thus are easier to detect. The U.S. Food and Drug Administration (FDA; Rockville, MD, USA) has cleared the PGD test system for marketing.


Related Links:
Verax Biomedical
Food and Drug Administration