No for Reagent Strips as a Predictor of Bacterial Contamination in Platelet Concentrates

Public awareness has long focused on the risks of the transmission of viral agents through blood product transfusion this risk, however, pales in comparison to the less publicized danger associated with the transfusion of blood products contaminated with bacteria, in particular, platelet concentrates [PC]. It has been suggested that measuring the pH and glucose level of PC using reagent strips can serve as a suitable measure for detection of any bacterial contamination. A total of 500 random donor platelets pool units with a shelf life of 6 days were screened for bacterial contamination using urine reagent strips [Combi-Screen, Analyticon, Germany]. Glucose and pH were measured; results were compared with quantitative culture using aerobic blood culture bottles.  A glucose level less than 250 mg per dL and/or a pH value of less than 7.0 was considered positive indication for bacterial contamination. Of the 500 PCs that were screened using reagent strips, 257 had a pH value of less than 7.0 [51.4%] with one sample only showing a concomitant hypoglycemia with glucose level of 100 mg/dl while none showed bacteria growth on culture. On the other hand 4 bacterially contaminated PC units with colony count >105 CFU/ml were not detected by reagent strips, as they were of normal ph and glucose levels, this was associated with a sensitivity and specificity of 0% and 51.8%, respectively. So the use of reagent strips for the detection of bacterially contaminated platelets should be reconsidered.