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.


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 1×10(3) and 1×10(8) 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.
Barker
Lynn M
LM
Blood Cell Storage, Inc. (BCSI), Seattle, Washington, usa.
Nanassy
Oliver Z
OZ
Reed
Michael W
MW
Geelhood
Steven J
SJ
Pfalzgraf
Randy D
RD
Cangelosi
Gerard A
GA
De Korte
Dirk
D
D001424:Bacterial Infections / Q000097:blood / Q000175:diagnosis* / Q000378:metabolism; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods; D001774:Blood Chemical Analysis / Q000379:methods* / Q000706:statistics & numerical data; D001792:Blood Platelets / Q000737:chemistry* / Q000378:metabolism / Q000382:microbiology; D001793:Blood Preservation / Q000592:standards; D058731:Blood Safety / Q000295:instrumentation / Q000379:methods; D001810:Blood Volume / Q000502:physiology; D002176:Candida albicans / Q000378:metabolism; D015169:Colony Count, Microbial; D004340:Drug Contamination; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010976:Platelet Count; D013211:Staphylococcus aureus / Q000378:metabolism