Comparative recovery of fungi from biphasic and conventional blood culture media

Abstract

A brain heart infusion broth and agar biphasic bottle was compared with a vented broth brain heart infusion bottle for the recovery of fungi from [human] blood. A total of 40 fungi, all yeasts, were recovered from 5000 blood cultures. The biphasic bottle slightly increased the overall recovery of 6 yeast spp. In addition, yeasts were first detected more often in the biphasic bottle (73%) than in the vented broth bottle (38%). A routine early (6-24 h) or late (5 day) subculture of macroscopically negative cultures may not be required for yeast isolation when a biphasic medium is used. Of the yeasts initially detected in the biphasic medium, 83% were seen to be growing on the agar slant. Only 4 were detected from a 24 h subculture; no biphasic isolate was recovered from a 5 day subculture. Only 1 yeast, a Candida glabrata of questionable clinical significance, was recovered after a routine blood culture period of 7 days; however, other fungi, not recovered in this study, require extended incubation periods.