ORIGINAL ARTICLE Effect of platelet additive solution on bacterial dynamics and their influence on platelet quality in stored platelet concentrates Carey A. Greco, Jerry G. Zhang, Miloslav Kalab, Qi-Long Yi, Sandra M. Ramirez-Arcos,* and Maria I.C. Gyongyossy-Issa* BACKGROUND: Platelet additive solutions (PASs) are an alternative to plasma for the storage of platelet con- centrates (PCs). However, little is known about the effect of PAS on the growth dynamics of contaminant bacteria. Conversely, there have been no studies on the influence of bacteria on platelet (PLT) quality indicators when suspended in PAS. STUDY DESIGN AND METHODS: Eight buffy coats were pooled, split, and processed into PCs suspended in either plasma or PAS (SSP+, MacoPharma). PCs were inoculated with 10 and 100 colony-forming units (CFUs)/bag of either Serratia liquefaciens or Staphylo- coccus epidermidis. Bacterial growth was measured over 5 days by colony counts and bacterial biofilm for- mation was assayed by scanning electron microscopy and crystal violet staining. Concurrently, PLT markers were measured by an assay panel and flow cytometry. RESULTS: S. liquefaciens exhibited an apparent slower doubling time in plasma-suspended PCs (plasma-PCs). Biofilm formation by S. liquefaciens and S. epidermidis was significantly greater in PCs stored in plasma than in PAS. Although S. liquefaciens altered several PLT quality markers by Days 3 to 4 postinoculation in both PAS- and plasma-PCs, S. epidermidis contamination did not produce measurable PLT changes. CONCLUSIONS: S. liquefaciens can be detected more quickly in PAS-suspended PCs (PAS-PCs) than in plasma-PCs by colony counting. Furthermore, reduced biofilm formation by S. liquefaciens and S. epidermidis during storage in PAS-PCs increases bacteria availabil- ity for sampling detection. Culture-based detection remains the earliest indicator of bacterial presence in PAS-PCs, while changes of PLT quality can herald S. liquefaciens contamination when in excess of 10 8 CFUs/mL. P latelet concentrates (PCs) are transfused to treat bleeding diatheses and to provide prothrom- botic support after chemotherapy. As an alterna- tive to storage in plasma, platelet additive solutions (PASs) were created to decrease plasma-related transfusion reactions as well as to conserve plasma for fractionation. 1 First-generation PASs (e.g., PlasmaLyte A, T-Sol, Baxter, Deerfield, IL) were sodium-citrate-acetate chloride solutions. Subsequent formulations were supple- mented with potassium and magnesium for the suppres- sion of platelet (PLT) metabolism to slow progression of the PLT storage lesion. 2 For improved buffering capacity, SSP+ (MacoPharma, Tourcoing, France), Composol (Fres- enius, Bad Homburg, Germany), and PAS-G (Pall Corp., Port Washington, NY) were created by augmenting the earlier formulations with phosphates, gluconate, or glu- cose. 3,4 The influence of PASs and PAS components on the quality of stored PLTs is well documented, and PASs are ABBREVIATIONS: CBS = Canadian Blood Services; CoNS = coagulase-negative staphylococci; MPV = mean platelet volume; netCAD = Network Centre for Applied Development; PAS(s) = platelet additive solution(s); PAS-PCs = PAS-suspended platelet concentrates; PC(s) = platelet concentrate(s); pCO2 = partial pressure of carbon dioxide; plasma-PCs = plasma-suspended platelet concentrates; pO2 = partial pressure of oxygen; SEM = scanning electron microscopy. From the Canadian Blood Services, Ottawa, Ontario; the Centre for Blood Research, University of British Columbia,Vancouver, British Columbia; and Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada. Address reprint requests to: Sandra M. Ramirez-Arcos, MSc, PhD, Development Scientist, Canadian Blood Services, 1800 Alta Vista Drive, Ottawa, Ontario, Canada K1G 4J5; e-mail: sandra.ramirez@blood.ca. *Both authors contributed equally to the manuscript. Received for publication March 5, 2010; revision received April 8, 2010, and accepted April 18, 2010. doi: 10.1111/j.1537-2995.2010.02726.x TRANSFUSION **;**:**-**. Volume **, ** ** TRANSFUSION 1