Effect of dilution on recovery of bacteria from blood.

The multiplication rate of bacteria in undiluted blood containing sodium polyanethol sulfonate was compared with growth rates obtained in dilutions of blood ranging from 1:2 to 1:8. Although all organisms tested grew in the undiluted blood, increased growth rates were seen in the 1:2 dilution. Further dilution resulted in growth rates equivalent to that obtained with the 1:2 dilution. In view of these results, we question the present recommendations that blood be diluted 1:10 or 1:20.