pH changes caused by bacterial growth in contaminated platelet concentrates

While platelet concentrates are stored at room temperature, lactic and other acids are produced and the pH decreases as the buffering capacity of the plasma is exhausted. Platelet viability will be compromised if the pH decreases to pH 6.0 and below. Similarly, a pH decrease can be produced also by bacterial contamination if the organisms produce acid as an end product. Thus the determination of pH could serve as a sensitive indicator of bacterial contamination. This hypothesis was tested by us by inoculating known organisms into platelet concentrations. It was found that the pH may decrease, may remain unchanged, or, in a few cases, even increase. Visual signs of contamination could be observed but not consistently enough to be entirely dependable. Therefore, this method does not appear to detect bacterial contamination reliably in platelet concentrates.