Rapid detection of bacteremia caused by Enterobacteriaceae with subculture in broth and laser nephelometry.

The early detection of Gram-negative rod bacteremia favors the prompt institution of appropriate antimicrobial therapy. During a 6-week period, blood cultures were subcultured in broth during the first 18 h of incubation. The turbidity of these subcultures was studied by laser nephelometry. Fifty-five percent of the blood cultures positive for Enterobacteriaceae were reported on the same day the sample was taken from the patient; this constitutes a marked acceleration in comparison with the results obtained by a conventional method. The identification and results of the antimicrobial susceptibility tests were available 2 days after the specimen was taken. Early subculture in broth combined with laser nephelometry studies of broth turbidity is readily applied to the study of bacteremia due to Enterobacteriaceae and may favorably influence the outcome of such disease by providing specific results more rapidly.