Coagulase-negative staphylococcal contamination of whole blood and its components: the effects of WBC reduction.

摘要

BACKGROUND: Most bacteria present in blood components are normal skin flora, particularly Staphylococcus epidermidis and other coagulase-negative staphylococci. Growth patterns of these bacteria and the effects of different methods of component preparation may depend on variations in behavior between different isolates of the same species. STUDY DESIGN AND METHODS: Whole-blood units were inoculated with 19 different coagulase-negative staphylococcus (CNS) isolates at 1 to 10 and 10 to 100 CFUs per mL. After overnight holding at 22 degrees C, the units were processed into components. The components were cultured before inoculation and during processing, including before and after WBC reduction. RESULTS: At low inoculum levels, CNS was detected in 15 (79%) of 19 whole-blood units and in 12 (63%) of 19 RBCs after separation; after filtration, bacteria were detected in 3 (16%) of 19 (p = 0.0069). For platelet concentrates, 6 (32%) of 19 grew bacteria before filtration and 1 of 18 after filtration (difference not statistically significant). Three (16%) of 19 plasmas were positive before and after freezing. At high inoculum levels, 16 (89%) of 18 whole-blood samples and RBCs were positive before filtration; 6 (33%) of 18 RBCs were positive after filtration (p = 0.0002); 8 (44%) of 18 platelets were positive before filtration; 3 (17%) of 18 were positive after filtration (difference not statistically significant), and 7 (37%) of 18 plasma samples were positive before and after freezing. CONCLUSION: The growth characteristics of CNS in blood components vary with differences either in the subtype of bacteria or in the donor blood. Filtration reduces but does not eradicate contamination of RBCs and platelets by CNS. Plasma may act as a reservoir for CNS infection.