Original Article

Ann Lab Med 2013; 33(6): 406-409

Published online November 1, 2013

Copyright © Korean Society for Laboratory Medicine.

Growth Dynamics of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa as a Function of Time to Detection in BacT/Alert 3D Blood Culture Bottles with Various Preincubation Conditions

Dong-Hyun Lee, M.D., Eun-Ha Koh, M.D., Sae-Rom Choi, M.T., and Sunjoo Kim, M.D.

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

Correspondence to: Sunjoo Kim
Department of Laboratory Medicine, Gyeongsang National University School ofMedicine, Gangnam-ro 79, Jinju 660-702, Korea
Tel: +82-55-750-8239
Fax: +82-55-762-2696

Received: October 23, 2012; Revised: December 1, 2012; Accepted: July 9, 2013

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.


Background: Delayed entry of blood culture bottles is inevitable when microbiological laboratories do not operate for 24 hr. There are few studies reported for prestorage of these bottles. The growth dynamics of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa were investigated with respect to various preincubation conditions. Methods: Fifteen or 150 colony-forming units (CFU) of bacteria were inoculated into standard aerobic or anaerobic blood culture bottles. Bottles were preincubated at 25°C or 37°C for 0, 2, 4, 8, 12, 24, or 48 hr. The time to detection (TTD) then was monitored using the BacT/Alert 3D system (bioMerieux Inc., USA). Results: Significant difference in TTD was observed following preincubation for 8 hr at 25°C vs. 4 hr at 37°C for S. aureus, 4 hr at 25°C vs. 4 hr at 37°C for E. coli, 12 hr at 25°C vs. 4 hr at 37°C for P. aeruginosa, compared to no preincubation (P<0.005). TTD values did not vary significantly with bacterial CFU or with aerobic or anaerobic bottle type. The BacT/Alert 3D system returned false negatives following preincubation of P. aeruginosa for 48 hr at 25°C or 24 hr at 37°C. Conclusions: TTD was mainly affected by preincubation temperature and duration rather than by input CFU quantity or bottle type for the 3 experimental bacteria.

Keywords: Blood culture, Detection, Storage, Preincubation