Time-to-Detection Comparison for a Novel Blood Culture System Using Simulated Blood Cultures: DLTM versus BacT/ALERTTM and BACTECTM.

Abstract

Automated blood culture systems are routinely used in microbiology laboratories to isolate bacteria and fungi causing bloodstream infections. A novel automated blood culture system, DL-Bt112TM (DL) was compared with the BACTEC 9050TM (BCT) and BacT/Alert 3DTM (B3D) systems for time-to-detection (TTD) using 10 different clinical bacteria that commonly cause bloodstream infections. Simulated blood cultures were used to compare the three automated blood culture systems. Blood drawn from healthy donors was inoculated with known concentrations of 10 different species of commonly isolated bacteria and analysed using the automated systems. TTD values for the three systems were recorded and analysed. Significant differences in the TTD were observed among the three systems. The DL system exhibited the longest detection time of all the systems (p < 0.0001). The BCT and B3D systems were superior to the DL system for all Gram-positive and most Gram-negative bacteria. No significance difference was observed between the BCT and the B3D systems when overall TTD values were evaluated; however, the BCT system yielded significantly better results than did the B3D system for the Gram-positive bacteria. TTD values were longer for the DL system than for the two commonly used blood culture systems when tested on simulated blood cultures. Thus, clinical laboratories considering the DL system should take its long TTD into consideration.