Performance of the BacT/Alert Virtuo Microbial Detection System for the culture of sterile body fluids: prospective multicentre study

Abstract

ObjectivesContinuous monitoring blood culture systems are commonly used for sterile body fluid cultures. In this multicentre study, we evaluated the performance of the new-generation BacT/Alert Virtuo system compared to the BacT/Alert 3D and conventional culture for the recovery of microorganisms from sterile body fluids. MethodsPeritoneal, cerebrospinal, pericardial, pleural and synovial fluids from adult patients submitted for culture were collected from three different centres. Specimens were inoculated into two bottles of the same bottle type (SA, SN, FA Plus or FN Plus) in equal volumes for simultaneous incubation in the Virtuo and 3D instruments. Each specimen was also Gram stained and seeded to solid media. ResultsA total of 811 specimens were inoculated to 1257 bottle pairs. The Virtuo and 3D showed equivalent recovery of clinically significant microorganisms (127/155, 81.9%, vs. 126/155, 81.3%, respectively). Solid media cultures recovered fewer pathogens than either continuous monitoring system (95/155, 61.3%, p <0.001), including significantly fewer Enterobacteriaceae and enterococci. The Virtuo was significantly faster than the 3D in median time to detection of isolates from the same specimen (12.5 (range, 2.8–101.5) hours vs. 15.5 (range, 4.3–78.5) hours, p <0.001). Direct specimen Gram stain detected the eventual pathogen in 30 (26.1%) of 115 significant positive specimens. ConclusionsThe BacT/Alert Virtuo system was equivalent to the 3D system in organism recovery from sterile body fluid culture but showed faster detection of growth as a result of design enhancements.