Multiple pH measurement during storage may detect bacterially contaminated platelet concentrates

BACKGROUND: Bacterial contamination or platelet (PLT) metabolism can change the pH of stored PLT concentrates (PCs). Measurement of pH for quality control is currently done on a limited basis. An easy noninvasive method was developed to obtain sequential pH measurements over time, without risking contamination and/or consuming PCs. STUDY DESIGN AND METHODS: The objective was to measure pH profiles of bacterially contaminated PCs over 7 days of storage. Small-volume PC storage bags with incorporated pH sensor were prepared and in vitro variables were tested using aliquots of PCs. The pH sensors were used to delineate trends associated with the deterioration of these PCs upon inoculation with 19 different bacterial strains and one yeast. RESULTS: Monitoring the pH trends in real time in a noninvasive fashion, most bacterial strains were detected within 24 to 72 hours after spiking into the bag. At the time of detection, bacterial concentrations had reached levels between 1 x 103 and 1 x 108 colony-forming units/mL. Several strains had pH rebound after initial drop. Multiple noninvasive pH reads allowed bacterial detection whereas single pH reads could give false-negative results. CONCLUSIONS: The noninvasive pH sensor facilitated the detection of most strains of bacterial contaminants within 3 days with no potential for sampling error.