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

摘要

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 Conclusions: TTD was mainly affected by preincubation temperature and duration rather than by input CFU quantity or bottle type for the 3 experimental bacteria.