Study on the usefulness of hypertonic culture media

Abstract

Specimens from 300 patients were studied using five to nine aerobic and anaerobic culture media, including five that were hypertonic, Groups studied included fever of unknown origin, suspected endocarditis, endocarditis during therapy, bacteremia during therapy, abscess and cellulitis, presumed infectious arthritis, renal transplantation during rejection, collagen disease, sarcoidosis, lymphoma, and colitis. Isolates in hypertonic media were reverted to parent form by agar passage. In only 5% of these selected cases were organisms found in hypertonic, but not conventional, media that appeared on the basis of repeated isolation and/or serological studies to come from the patient. Nine of the 16 appeared to be of major significance. The two groups in which use of highly enriched, hypertonic media seemed most helpful were suspected endocarditis and undefined meningitis with negative cultures using standard media. The most effective of the hypertonic media used was 0.3 M sucrose in brain heart infusion with 20% horse serum. In most instances, the organism grew only in the hypertonic sucrose, and in most cases it appeared in conventional rather than aberrant form. Hypertonic media, especially 0.3 M sucrose, are of substantial helpin a small number of carefully selected cases.

Invited commentary

“…If blood cultures are negative using standard media, then it may be beneficial to place blood specimens in hypertonic (10% sucrose) media [8]. It is also well to point out that if a patient with unexplained fever, especially a drug user, has isolated from the blood a Candida species other than C. albicans or C. tropicalis--species such as Candida parapsilosis or Candida guilliermondii--it is very likely that the patient has endocarditis.…”