Practical aerobic membrane filtration blood culture technique: clinical blood culture trial

During the course of preliminary clinical trials of an improved membrane filter blood culture system, filter plugging produced by a gelling of the lysing solution was observed when the patients had high leukocyte counts. A solution of streptokinase-streptodornase (Varidase, Lederle Laboratories) dissolved or prevented the gel and permitted rapid filtration without plugging. With streptokinase-streptodornase incorporated in the filtration procedure, a comparison of several culture systems was carried out on 176 blood cultures. Brucella broth with and without sodium polyanethol sulfonate, a prereduced osmotically stabilized broth, pour plates, and an improved aerobic membrane filter system were compared. The membrane filter system yielded 29 of the total of 37 positive cultures, far surpassing all other systems. Eight of these cultures were detected first by the filter technique, and 13 were positive only in this system. Nineteen of the 37 positive cultures were from patients on antimicrobial agents. Fourteen of these were detected by the filter, twice the number detected by any of the other systems.