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Rapid detection of contaminant bacteria in platelet concentrate using differential impedance
Author(s) -
Zhao Z.,
Chalmers A.,
Rieder R.
Publication year - 2014
Publication title -
vox sanguinis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.68
H-Index - 83
eISSN - 1423-0410
pISSN - 0042-9007
DOI - 10.1111/vox.12144
Subject(s) - bacteria , contamination , bacterial growth , lysis , centrifugation , chromatography , microbiology and biotechnology , differential centrifugation , incubation period , chemistry , incubation , biology , immunology , biochemistry , ecology , genetics
Background and Objectives Current FDA ‐approved culture‐based methods for the bacterial testing of platelet concentrate ( PC ) can yield false‐negative results attributed to Poisson‐limited sampling errors incurred near the time of collection that result in undetectable bacterial concentrations. Testing PC at the point of issue ( POI ) extends the incubation period for any contaminant bacteria increasing the probability of detection. Data are presented from time–course experiments designed to simulate POI testing of bacterially contaminated PC s at different stages of growth using differential impedance sensing. Study design and methods Whole‐blood‐derived PC s were typically spiked with low numbers of bacteria (approximately 100  CFU /ml) and incubated under standard PC storage conditions. Each infected unit was evaluated every two hours over a 12‐h period. All samples were treated with a chemical compound that induces stress in the bacterial cells only. The development of any bacterial stress was monitored by detecting changes in the dielectric properties of the PC using differential impedance. Results Differential impedance measurements and corresponding cell counts at the different time‐points are presented for six organisms implicated in post‐transfusion–septic reactions. All infected PC s were detected once contaminant bacteria reached concentrations ranging between 0·6 × 10 3 and 6 × 10 3   CFU /ml irrespective of the phase of growth. Results were obtained within 30 min after the start of the assay and without the need for cell lysis or centrifugation. Conclusion Differential impedance sensing can detect bacterial contamination in PC rapidly at concentrations below clinical thresholds known to cause adverse effects.

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