Effects of two blood culture anticoagulants on growth of Neisseria meningitidis.

Tests of 25 strains of Neisseria meningitidis for sensitivity to sodium polyanethol sulfonate (SPS) showed that the sensitivity of strains varied with both inoculum size and SPS concentration. In Trypticase soy broth (TSB), 2 out of 13 strains were sensitive to 0.05% SPS, whereas 8 out of 13 strains were sensitive to the same concentration of SPS in brain heart infusion (BHI). In artificial blood cultures with six strains of meningococci, the addition of 10% defibrinated blood was found to eliminate the sensitivity of all six strains to SPS in BHI, but not of the two strains in TSB. Addition of 1.2% gelatin to artificial blood cultures eliminated the inhibitory effect of 0.05% SPS, whereas the addition of 1% yeast extract to blood cultures containing 0.025% or 0.05% SPS enhanced the inhibitory effect of this anticoagulant. None of the 13 strains tested was inhibited by 0.05% sodium amylosulfate in TSB or BHI alone or in artificial blood cultures with these media.