Evaluation of the Sensitivity and Specificity of Use of Glucose and pH for Bacterial Screening of Platelet Concentrates Compared to the Bact/Alert.

Bacterial contamination of blood components is the major infectious risk in transfusion medicine. Since platelets should be stored at room temperature that makes them an excellent growth medium for bacteria; it is mentioned as a major problem in transfusion medicine. Transfusion risk of a bacterial contaminated platelet concentrate is higher than viral pathogen such as HIV, HBV, HCV and HTLV. The objective of this study was to evaluation of the sensitivity and specificity of use of glucose and pH for bacterial screening of platelet concentrates compared to the Bact/Alert. 1332 platelet concentrates were screened by the Bact/Alert system for aerobic and anaerobic bacterial contamination. Bacterial contamination was also evaluated by using urine reagent strips (Multistix10 SG Bayer) and culture methods. Moreover PH screening with a pH meter (Metrohm 744 Swiss) and glucose was also used for detection of bacterial contamination. The rate of bacterial contamination detected by the Bact/Alert system in platelet concentrates was 25 in 1332 (1.9 %). It contained 15 (1.1 %) for aerobic bacteria and 10 (.8 %) for anaerobic bacteria. 226 of 1332 were considered as containing bacteria by using urine reagent strips. Six of the 226 units were also positive by the Bact/Alert system. Three of those units were culture positive for aerobic bacteria and three for anaerobic. The result of platelet concentrates that underwent pH screening by use of pH meter and a pH portion of urine reagent strips was the same. The sensitivity and specificity of considering glucose alone for detection of bacterial contamination were 12 and 98 % respectively. For pH alone, these were 24 and 83 %. For glucose and/or pH, these were 24 and 83 %; and for combination of glucose and pH, these were 12 and 98 %. Our results showed use of glucose/pH strips would improve the safety of blood products and should be encouraged.