Impact of rapid microbial identification on clinical outcomes in bloodstream infection: the RAPIDO randomised trial.

Abstract Objectives Bloodstream infection has a high mortality rate and it was not clear whether laboratory-based rapid identification of the organisms involved would improve outcome. Methods The RAPIDO trial was an open parallel-group multi-centre randomised controlled trial. We tested all positive blood cultures from hospitalised adults by conventional methods of microbial identification and those from patients randomised (1:1) to rapid diagnosis, in addition, by matrix-assisted laser desorption/ionisation time of flight (MALDI-TOF) mass spectrometry directly on positive blood cultures. The only primary outcome was 28-day mortality. Clinical advice on patient management was provided in both groups by infection specialists. Results First positive blood culture samples from 8,628 patients were randomised, 4,312 into rapid diagnosis, 4,136 into conventional. After pre-specified post-randomisation exclusions, 2,740 in the rapid diagnosis arm and 2,810 in the conventional were included in mortality analysis. There was no significant difference in 28-day survival (81·5% 2233/2740 rapid vs 82·3% 2313/2810 conventional; HR 1·05, 95% CI 0·93–1·19, p=0·42). Microbial identification was quicker in the rapid diagnosis group (median 38·5 vs 50·3 hours after blood sampling, IQR 26·7–50·3 vs 47·1–72·9, p Conclusions Rapid identification of bloodstream pathogens by MALDI-TOF in this trial did not reduce patient mortality despite delivering laboratory data to clinicians sooner.