Ann Clin Microbiol.  2014 Dec;17(4):105-109. 10.5145/ACM.2014.17.4.105.

Effect of Preincubation of Blood Culture Bottles in a BacT/Alert Unit Outside Laboratory Operating Hours on Detection Time

• Kim JS
• Seok H
• Kim S

• KMID: 1971104
• DOI: http://doi.org/10.5145/ACM.2014.17.4.105

Abstract

BACKGROUND
The pre-storage condition of blood culture bottles prior to entering the automated blood culture system may affect the time to detection (TTD) of microorganisms and the final report days.
METHODS
We compared the TTD and final report days according to the pre-incubation conditions after laboratory operating hours: room temperature (RT) vs. a BacT/Alert unit (BioMerieux Inc.) for 3 months respectively. All bottles were inserted into the main BacT/Alert system the next morning.
RESULTS
TTD was significantly reduced by pre-incubating bottles in a BacT/Alert unit (median, 8.4 h) compared to pre-storage at RT (median, 12.4 h) (P< 0.001). The final report of bacterial identification and drug susceptibility within 2 days was available for 24.4% of bottles pre-incubated in a BacT/Alert unit compared to 14.9% of those incubated at RT. The false positive results were significantly higher for pre-incubation in a BacT/Alert unit (0.81%) than for that (0.29%) at RT (P<0.001).
CONCLUSION
If a clinical microbiology laboratory is not operational for 24 hours, an automated blood culture unit might be a good alternative to reduce TTD and allow the submission of a faster final report compared to pre-storage at RT. However, false positive readings increased more than two-fold by pre-incubation in a BacT/Alert unit.

Keyword

Blood culture; Delayed entry; Detection time; False positive; Preincubation

MeSH Terms

Reading

Figure

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  Fig. 1. Comparison of time to detection (TTD) of (A) all microorganisms, (B) Gram (+) organisms, (C) Gram (-) organisms, and (D) yeasts according to prestorage of blood culture bottles at room temperature and in a BacT/Alert unit outside laboratory operating hours. P＜0.001 in (A), (B), and (C) by Mann-Whitney U test.

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  Fig. 2. Final report days of blood culture from bottle entry preincubated at room temperature (RT) or in a BacT/Alert unit outside laboratory operating hours. P=0.052 by χ2 test.

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