Comparison of Oxoid Signal and biphasic blood culture systems in clinical practice

The 1-bottle Oxoid Signal blood culture system was compared with a biphasic 2-bottle system in a clinical trial. A total of 851 routine blood samples were processed in the study which was run as a multicenter study at 4 university hospitals. Microorganisms were isolated from 104 (12.2%) blood cultures by one or both methods. 75 (72%) were clinically significant isolates, 61 of them were recovered in both systems, 9 in Oxoid Signal only and 5 in the biphasic system only. 29 isolates (28%) were judged as contaminants, 6 of them were found in both systems, 18 in Oxoid Signal only and 5 in the biphasic system only. The Oxoid Signal System had many advantages although it sometimes gave false positive signals in the device. The growth of pathogens was equally good, 93% versus 88% positive cultures.