Blood is one of the most important clinical specimens for the isolation of bacteria. A rapid isolation and a high isolation rate of bacteria are very important in blood culture because bacteremic patients are mostly in grave condition. Various blood culture media which support growth of most fastidious bacteria are available commercially. However, growth of bacteria are frequently delayed because of antibacterial activity of blood.
Sodium polyanethol sulfonate (Liquoid) has been reported to inactivate the antibacterial substance and disrupt phagocytic cells. The beneficial effect of SPS is well recognized in the isolation of gram-positive bacteria. However, the effect does not seem to be prominent for gram-negative bacilli isolation mainly due to the rapidity of their growth.
It has been experienced with Sal. typhi that the growth is much slower than that of other gram-negative bacilli. For the rapid growth of the organism, use of bile broth has been recommended. Although Sal. typhi is the most frequently isolated organism at present, about one half of total isolates are other organisms and; in case bile broth is used, other media which support growth of these organisms should be used together. Fluid thioglycollate medium (FTM) which is always used in blood culture to isolate anaerobes is inferior to brain heart infusion (BHI) for the isolation of aerobes.
This study was done to determine the effect of SPS on the isolation of Sal. typhi from blood. During the Sep. 1973 to Sep. 1974 study period, 2460 blood cultures were made from the Severance hospital patients: BHI and FTM sets 1431 specimens, BHI with SPS (0. 05%) and FTM sets 396 specimens, BHI and FTM with SPS sets 359 specimens, BHI and BHI with SPS sets 274 specimens.
Mean incubation time required for the macroscopic detection of growth of Sal. typhi were 3.5 days on BHI and 2. 7 days on BHI with SPS. The 0.8 day difference was statistically significant. On FTM the mean incubation time was 3.8 days while it was 2.9 days on FTM with SPS. The 0. 9 day difference was statistically significant.
The result on BHI with and without SPS sets showed faster growth on BHI with SPS in 7 specimens and slower growth in one specimen and the remaining 12 showed growth at the same time. These specimens had mean incubation time of 3.2 days on BHI and 2. 3 days on BHI with SPS. The 0. 9 day difference was statistically significant.
This study indicates beneficial effect of SPS for the rapid isolation of Sal. typhi from clinical blood specimens.
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