Variable neutralization of several nonspecific antibacterial systems in fresh, defibrinated human blood by sodium...

Fresh, defibrinated human blood (80 vol%, i.e., 80% [vol/vol] of a 2-ml final assay volume) from two healthy adult donors killed "delayed serum-sensitive" (DSS) and "promptly serum-sensitive" (PSS) strains of Serratia marcescens, PSS control strain Escherichia coli C, Bacillus subtilis strain ATCC 6633, and Micrococcus lysodeikticus ATCC 4698 in a kinetic manner comparable to that of fresh human serum (80 vol%). However, heat-inactivated (56 degrees C, 30 min), defibrinated human blood revealed markedly reduced or a total lack of beta-lysin activity against the B. subtilis assay strain. Similarly, lysozyme activity of defibrinated blood was diminished somewhat by heat treatment, as determined with the M. lysodeikticus assay strain. Addition of 500 mug of sodium polyanetholsulfonate (SPS) per ml to 80 vol% of fresh, defibrinated human blood completely neutralized blood bactericidal activity against all assay strains of S. marcescens, E. coli C, and B. subtilis; however, SPS at this concentration failed to abolish lysozyme activity for prolonged periods of incubation. Addition of 500 mug of sodium amylosulfate (SAS) per ml to 80 vol% of fresh defibtinated human blood resulted in protection of cell inocula of DSS strains of S. marcescens only; SAS failed to protect cell inocula of the PSS strains of S. marcescens, E. coli C, B. subtilis, and M. lysodeikticus for extended periods of observation. Based on these data, it is recommended that blood culture specimens that are first drawn into specimen containers (such as Vacutainer tubes or the like) at the patient's bedside, and which contain >/=250 mug of SPS per ml, be diluted into suitable broth media with at least >/=250 mug of SPS per ml by the receiving laboratory within 2 to 4 h after procurement of the specimen. This procedure would ensure continued, adequate neutralization of the specimen's inherent beta-lysin, lysozyme, and complement- and antibody-mediated bactericidal activities.