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Noninvasive pH monitoring for bacterial detection in platelet concentrates
Maria Loza-Correa1, Heather Perkins1, Dilini Kumaran1
1Canadian Blood Services, Ottawa, Ontario, Canada.
Background:
Bacterial contamination of platelet concentrates (PCs) remains the prevalent posttransfusion infectious risk. The pH SAFE system, a noninvasive method used to measure pH of PC for quality control, was evaluated herein as a rapid method to detect bacterial contamination in PCs.
Study Design And Methods:
Pairs of ABO-D-matched apheresis and buffy coat PCs were pooled and split into two pH SAFE platelet bags. One of the bags served as the control unit, while the other was inoculated with one of nine clinically relevant bacteria (target concentration approx. 1 colony-forming units [CFUs]/mL). The pH of both PCs was measured over 7 days of storage at approximately 4-hour intervals during daytime. One-milliliter samples were taken at the testing points to determine bacterial concentration.
Results:
PCs with pH values of less than 6.6 or with a pH change over time (ΔpH/Δtime) greater or equal than 0.046 pH units/hr are suspected of being contaminated. pH decreased significantly during storage in all bacterially inoculated PC at concentrations of more than 10(7) CFUs/mL (p < 0.0001). A significant decrease in pH (p < 0.0001) was noticed as early as 28 hours in units with Bacillus cereus and as late as 125 hours in units containing Staphylococcus epidermidis. Interestingly, PCs containing Gram-negative species showed a decline in pH followed by a rebound.
Conclusions:
The pH SAFE system allows for repeated, noninvasive pH screening during PC storage. A significant decrease in pH could serve as an indicator of clinically significant levels of bacterial contamination. Since differences in pH decline were observed among bacterial species, continuous pH monitoring in PCs is recommended.
Insights
The pH SAFE system can detect bacterial contamination in platelet concentrates (PCs) by monitoring pH changes. A significant pH decrease indicates contamination, recommending continuous pH monitoring for quality control.
Area of Science:
- Transfusion Medicine
- Microbiology
- Medical Device Technology
Background:
- Bacterial contamination of platelet concentrates (PCs) is a major post-transfusion infectious risk.
- The pH SAFE system offers a noninvasive method for PC quality control by measuring pH.
Purpose of the Study:
- To evaluate the pH SAFE system as a rapid method for detecting bacterial contamination in PCs.
- To assess the correlation between pH changes and bacterial load in stored PCs.
Main Methods:
- Platelet concentrates were inoculated with various bacteria at low concentrations.
- pH was measured noninvasively over 7 days using the pH SAFE system.
- Bacterial concentration was determined through sample analysis.
Main Results:
- A significant decrease in pH was observed in PCs with bacterial concentrations exceeding 10^7 CFUs/mL.
- pH decline was detected as early as 28 hours for Bacillus cereus and 125 hours for Staphylococcus epidermidis.
- Gram-negative bacteria showed an initial pH decline followed by a rebound.
Conclusions:
- The pH SAFE system enables repeated, noninvasive pH screening of PCs during storage.
- A significant pH decrease can indicate clinically relevant bacterial contamination.
- Continuous pH monitoring is recommended due to species-specific pH decline patterns.
