ABSTRACT
BACKGROUND: Platelet (PLT) transfusion-associated bacterial sepsis has remained a substantial patient risk, primarily due to lacking effective and point-of-issue measures to detect bacterial contamination. This study describes near infrared (NIR) spectroscopy to examine inoculated PLTs without sampling within a few seconds. STUDY DESIGN AND METHODS: This study evaluated apheresis PLTs inoculated with low concentrations of Bacillus cereus and Staphylococcus epidermidis, comparing with sterile bags. Short-wavelength NIR spectra over the range from 700 to 1100 nm in the transmittance mode were obtained using research (NIRS6500, Foss NIRSystems) and portable (NIRGun, Shizuoka Shibuya Seiki) instruments at 6-hour intervals from 0 to 72 hours after inoculation (HAI). RESULTS: The sensitivity of the NIRS6500 was 100% (43/43) and 98% (50/51) after incubating PLTs inoculated with B. cereus for 42 HAI or more and with S. epidermidis for 54 HAI or more, respectively. Difference spectra calculated by subtracting the NIR spectra of stored PLTs with that of the same PLTs measured at 0 HAI improved the discrimination results compared with conventional second derivative spectra. CONCLUSION: The NIRS6500 system can provide a PLT monitoring system based on difference spectra. The chemical components of PLTs that were influenced by bacterial metabolism seemed to play an important role in the calibration structure. Further studies should examine samples spiked with various species of prevalent bacteria.
Subject(s)
Blood Banking/methods , Microbiological Techniques/instrumentation , Platelet Transfusion/standards , Spectroscopy, Near-Infrared , Staphylococcal Infections/prevention & control , Staphylococcus epidermidis/isolation & purification , Bacillus cereus/growth & development , Bacillus cereus/isolation & purification , Calibration , Equipment Contamination , Gram-Positive Bacterial Infections/blood , Gram-Positive Bacterial Infections/prevention & control , Gram-Positive Bacterial Infections/transmission , Humans , Microbiological Techniques/methods , Staphylococcal Infections/blood , Staphylococcal Infections/transmission , Staphylococcus epidermidis/growth & developmentABSTRACT
BACKGROUND: Bacterial contamination of platelet (PLT) products occurs at low concentrations requiring a period of incubation for growth to minimize sampling error. Culture-based detection methods also need sufficient incubation time; together these periods may limit the useful life of PLTs. This study characterizes the impact of sampling and detection times with two commercially available bacteria detection products. STUDY DESIGN AND METHODS: Apheresis PLTs inoculated with nine bacterial species at low concentrations were sampled immediately and 24 hours after inoculation. Test results were analyzed after incubation at 16, 20, and 24 hours after sampling with two bacterial detection systems. RESULTS: When sampled immediately after inoculation, two commercially available bacterial detection systems (BacT/ALERT, bioMérieux; and eBDS, Pall Corp.) failed to detect some PLTs inoculated with Staphylococcus epidermidis, Serratia liquefaciens, or Pseudomonas aeruginosa and S. epidermidis, S. liquefaciens, Bacillus cereus, or P. aeruginosa, respectively. The BacT/ALERT was better at 20 hours (p<0.02), but not at 16 or 24 hours for Time 0 sampling. When sampling occurred 24 hours after inoculation, there were no difference between the two systems. CONCLUSION: Results suggest that for either bacteria detection system, holding PLTs for 24 hours before sampling improves the detection sensitivity for PLTs contaminated with low concentrations of bacteria, and longer incubation periods improve detection.
