Bacteriologic Culture of Sterile Body Fluids: Assessment of a Protocol

Abstract

Results of routine bacteriologic cultures of 1,496 cerebrospinal fluid (CSF) specimens and 846 other normally sterile body fluid (SBF) specimens were examined for frequency of isolation of organisms, time required for detection, and correlation of Gram's stain and culture. Microorganisms were isolated from 104 CSF; however, 46 of these isolates were judged to be probable contaminants. The positive culture rate for CSF is then 3.9% (58/1496), and 11.8% (100/846) for SBF. The Gram's stain was of diagnostic value in 28% (16/58) of CSF and in 34% (34/100) of SBF. All Gram's stain-positive specimens were culture-positive within 24 hours. Of CSF and SBF isolates, 9 1% (53/58) and 88% (118/134), respectively, were recovered within 48 hours. Eight yeast isolates from CSF did not grow in a prereduced anaerobic broth. CSF and SBF specimen cultures require a minimum of 72 hours of incubation on appropriate media. Gram's stains are of diagnostic value in only one third of these specimens.