Controlled evaluation of hypertonic sucrose medium at a 1:5 ratio of blood to broth for detection of bacteremia and fungemia in supplemented peptone broth

Abstract

The value of hypertonic media in the detection of bacteremia and fungemia is controversial, since prior clinical trials have yielded conflicting results with different media. Earlier, we showed that the addition of 10% sucrose to supplemented peptone broth at a 1:10 ratio of blood to broth yielded better recovery of Staphylococcus epidermidis, the Enterobacteriaceae, Pseudomonas aeruginosa, and yeasts. To evaluate the effect of 10% sucrose on blood cultured at a 1:5 ratio, we compared the yield and speed of detection of clinically important microorganisms from adult patients in 5,839 blood samples cultured in supplemented peptone broth with 0.03% sodium polyanetholesulfonate with and without 10% sucrose. The atmosphere of incubation (open venting units), 1:5 ratio of blood to broth, and methods of processing were the same for both bottles. Recovery of facultative gram-positive (P < 0.02) and gram-negative (P < 0.02) bacteria was improved, but the recovery of anaerobic gram-negative bacteria was both reduced (P < 0.01) and delayed (P < 0.02) by sucrose. The total yield of microorganisms including fungi, however, was increased with sucrose. The effect of sucrose on blood cultures appears to depend on the ratio of blood to broth as well as on the medium used and strains of microorganisms encountered.