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Koh, Lee, and Kim: Effects of Preincubating Blood Culture Bottles at 37o C during the Night Shift and of Collected Blood Volume on Time to Detection and Days to Final Report
Original Article

Ann Clin Microbiol 2014;17(1):14-19.

Published online: 5 March 2014

DOI: https://doi.org/10.5145/ACM.2013.17.1.14

Effects of Preincubating Blood Culture Bottles at 37o C during the Night Shift and of Collected Blood Volume on Time to Detection and Days to Final Report

Eun-Ha Koh, Dong-Hyun Lee, Sunjoo Kim

Department of Laboratory Medicine, Gyeongsang Institute of Health Sciences, Gyeongsang National University School of Medicine, Jinju, Korea

Correspondence: Sunjoo Kim, Department of Laboratory Medicine, Gyeongsang National University School of Medicine, 79 Gangnam-ro, Jinju 660-702, Korea. (Tel) 82-55-750-8239, (Fax) 82-55-762-2696, (E-mail) sjkim8239@hanmail.net

Received 22 August 201321 November 2013       Accepted 30 November 2013

Copyright © 2014 The Korean Society of Clinical Microbiology

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

초록

Background

By varying the collected blood volume and storage temperature of the blood culture bottles prior to entry in an automated blood culture system, growth of organisms will be affected.

Methods

Blood culture bottles with a 20 mL blood volume per set were stored at 37o C (1st period) and room temperature (RT, 2nd period) upon arrival at the laboratory after working hours compared to baseline period (10 mL, RT). The time to detection (TTD) for all strains and the number of days until the final report after bottle entry were compared among the three periods.

Results

The median TTD for all strains was 13.5 h, 10.6 h, and 11.3 h in the baseline (N=268), 1st (N=454), and 2nd period (N=370), respectively (P＜0.001). The final identification report was available within two days of bottle entry for 12.3%, 30.6% and 15.1% of bottles in the three different periods, respectively (P＜0.001).

Conclusion

Collecting an adequate blood volume is critical to reduce TTD. The preincubation of blood culture bottles at 37o C during the night shift might enable earlier final reports than storage at RT for samples with the same collected blood volume.

Keywords: Blood culture, Detection, Storage

REFERENCES

1.Clinical and Laboratory Standards Institute. Principles and procedures for blood cultures; approved guidline. Document M47-A. Wayne, PA; Clinical and Laboratory Standards Institute. 2007.
2.Baron EJ., Weinstein MP, et al. Cumulative techniques and procedures in clinical microbiology. Washington; American Society of Microbiology. 2005. 1–16.
3.Shin JH., Song SA., Kim M., Kim S. Nationwide survey of blood culture performance regarding skin disinfection, blood collection and laboratory procedures. Korean J Clin Microbiol. 2011. 14:91–6.
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5.Kerremans JJ., van der Bij AK., Goessens W., Verbrugh HA., Vos MC. Immediate incubation of blood cultures outside routine laboratory hours of operation accelerates antibiotic switching. J Clin Microbiol. 2009. 47:3520–3.
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6.van der Velden LB., Vos FJ., Mouton JW., Sturm PD. Clinical impact of preincubation of blood cultures at 37°C. J Clin Microbiol. 2011. 49:275–80.
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Table 1.
Median time to detection (TTD) and interquartile range (IQR) according to the storage conditions of blood culture bottles and collected blood volume during the night shift
Strains RT 10 mL 37 o C 20 mL RT 20 mL 　 P value*
N Median TTD (IQR) N Median TTD (IQR) N Median TTD (IQR)
All strains 268 13.5 (8.6-24.9) 454 10.6 (5.5-19.6) 370 11.3 (7.2-18.1) ＜0.001
Gram-positives 142 18.4 (11.4-27.5) 207 13.7 (7.8-20.7) 152 14.3 (9.9-21.9) 0.001
Gram-negatives 109 8.8 (6.9-11.6) 230 7.3 (4.1-13.8) 200 8.8 (6.1-12.7) 0.003
Yeasts 17 40.5 (19.0-68.1) 17 29.9 (26.3-39.8) 18 38.8 (16.8-75.4) 0.592

∗ Kruskal-Wallis

Abbreviation: RT, test. T, room temmperature.

Table 2.
Time elapsed between bottle entry and blood culture report for bottles preincubated at room temperature (RT) and 37 o C during the night shift
Days RT 10 mL/set 37 o C 20 mL/set RT 20 mL/set
N % N % N %
2 33 12.3 139 30.6 56 15.1
3 140 52.2 179 39.4 212 57.3
4 58 21.6 83 18.3 47 12.7
≥5 37 13.8 53 11.7 55 14.9
Total 268 100 454 100 370 100

P < 0.001 by χ2 test.

Table 3.
Frequency of isolates from blood culture distributed by storage temperature and blood volume collected
　 RT 10 mL/set 37 o C 20 mL/set RT 20 mL/set P value†
N % N % N %
Gram (+) 142 53 207 45.6 152 41.1 0.012
  CoNS∗ 31 11.6 31 6.8 24 6.5  
  Enterococcus spp. 10 3.7 24 5.3 24 6.5  
  Staphylococcus aureus 48 17.9 54 11.9 32 8.6  
  Staphylococcus epidermidis 21 7.8 36 7.9 28 7.6  
  Streptococcus agalactiae 2 0.8 9 2 0 0  
  Streptococcus pneumoniae 8 3 10 2.2 8 2.2  
  Viridans group streptococci 19 7.1 28 6.2 3 0.8  
  Other gram-positives 3 1.1 15 3.3 33 8.9  
Gram (-) 109 40.7 230 50.7 200 54.1 0.003
  Acinetobacter spp. 3 1.1 14 3.1 13 3.5  
  Escherichia coli 57 21.3 116 25.6 80 21.6  
  Klebsiella pneumoniae 21 7.8 57 12.6 48 13  
  Pseudomonas aeruginosa 1 0.4 14 3.1 10 2.7  
  Salmonella Typhi 0 0 8 1.8 5 1.4  
  Other gram-negatives 27 10.1 21 4.6 44 11.9  
Yeasts 17 6.3 17 3.8 18 4.9 0.283
 Candida albicans 11 4.1 0 0 8 2.2  
 Candida non-albicans 6 2.2 17 3.8 10 2.7  
Total 268 100 454 100 370 100  

∗ CoNS, coagulase-negative staphylococci other than S. epidermidis.

† P value by χ2 test.

Abbreviation: RT, room temperature.

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