Comparative evaluation of conventional (manual) blood culture system and BacT/ALERT 3D (automated) blood culture system in a Tertiary care hospital

The prompt detection of bacteremia is a critical function of the clinical microbiology laboratory and blood culture remains the “gold standard” for the detection of bacteremia. Automated continuous-monitoring blood culture systems have detected growth sooner than the manual systems and they have greatly improved the efficiency of blood cultures. Here, in this hospital-based prospective study, we intended to compare such two systems with reference to yield, sensitivity and differential time to positivity. A total of 498 matched pairs of blood culture specimens were compared. Bacterial growth was identified in 183(36.74%) cultures by automated system and 146(29.31%) cultures by manual system (p=0.0153). The BacT/ALERT 3D system showed better sensitivity and specificity than manual culture system. The median time to positivity with the automated system was 15.83 hr, compared with 66.95 hr for the manual system (p<0.0001). Both systems were comparable for the recovery of majority of clinically significant isolates. The BacT/ALERT 3D automated system was very much superior to the manual culture system in the rapid detection of the organisms. The BacT/ALERT 3D ® automated microbial detection system evaluated in our study showed a marginally higher recovery rate than the conventional (manual) blood culture system used in our laboratory. However, the exceptionally faster detection rates shown by the automated system can significantly change the outcome in life threatening bloodstream infections.