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Comparative analysis of two blood culture systems (Isolator® and a 12‐tube system) by cumulative differences in detection power at different times during incubation
Author(s) -
ARPI MAGNUS,
PRAG JØRGEN,
SCHRØDER STEEN S.,
FREDERIKSEN WILHELM,
BENTZON MICHAEL WEIS
Publication year - 1988
Publication title -
apmis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.909
H-Index - 88
eISSN - 1600-0463
pISSN - 0903-4641
DOI - 10.1111/j.1699-0463.1988.tb05329.x
Subject(s) - incubation , isolator , agar plate , centrifugation , agar , staphylococcus aureus , incubation period , microbiology and biotechnology , staphylococcus , biology , chromatography , bacteria , chemistry , biochemistry , genetics , electronic engineering , engineering
A lysis‐centrifugation blood culture system (Isolator®) and a conventional system (4 tubes of nutrient broth, 4 tubes of semisolid agar, and 4 tubes of thioglycollate agar) were compared after different lengths of incubation by cumulative scoring of differences in detection power. After the first half day of incubation, the Isolator® system was already significantly faster in detecting isolates of clinical significance (15 vs. 4, P = 0.02). Maximum difference in first or only detection system was seen after two days of incubation and was based on an overall superior detection of Staphylococcus aureus (11 vs. 0, P = 0.001), and an earlier detection of Enterobacteriaceae (30 vs. 13, P = 0.01) in the Isolator® system. On the contrary, the detection of Streptococcus pneumoniae was significantly inferior in the Isolator® system (0 vs. 10, P = 0.002). The earlier finding of clinically significant microorganisms in the Isolator® system certainly contributes to good patient‐care. A drawback of the Isolator® system was the finding of clinically insignificant coagulase‐negative staphylococci in 11%, compared with 1% in the conventional system. This led to a considerable waste of time and materials in the laboratory. The comparison of the two blood culture systems, based on statistical analysis of cumulative differences in detection power, expressed as the earliest or only findings, gives the optimal information, and is in our opinion the clinically most relevant comparison.