Rapid detection of positive blood cultures with the BACTEC NR-660 does not require first-day subculturing

M. H. Levi, P. Gialanella, M. R. Motyl, J. C. McKitrick

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


An analysis of blood culture data was performed to determine whether subculturing within the first 24 h of incubation decreased the time to detection of positive blood cultures when compared with the routine use of the BACTEC NR-660 system (Johnston Laboratories, Inc., Towson, Md.). During a 9-month period (June 1985 to February 1986), 17,913 blood cultures were received in our laboratory, of which 1,463 (8.2%) became positive. Of the positive cultures, 97% were detected with equal or greater rapidity by the NR-660 system than by visual inspection and first-day blind subculturing. There were 37 delayed positive cultures from which only one isolate (0.07%) was not eventually detected by the NR-660 system. Coagulase-negative staphylococcus was the most frequent isolate among the delayed positive cultures, but only 3 of 15 isolates were known to be clinically significant isolates. The longest delay in detection by the NR-660 system was 6 days for one isolate of Cryptococcus neoformans and one isolate of Klebsiella pneumoniae. Although subculturing may decrease the time to detection of a few cultures, the majority of positive blood cultures were detected faster or with equal speed by the NR-660 system. When the data were evaluated, routine use of the NR-660 system was sufficient for the detection of positive blood cultures and was cost-effective.

Original languageEnglish (US)
Pages (from-to)2262-2265
Number of pages4
JournalJournal of Clinical Microbiology
Issue number11
StatePublished - 1988

ASJC Scopus subject areas

  • Microbiology (medical)


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