Impact of MALDI-TOF-MS-based identification directly from positive blood cultures on patient management: a controlled clinical trial.

OBJECTIVES: Rapid identification of pathogens directly from positive blood cultures (BC) in combination with an antimicrobial stewardship programme (ASP) is associated with improved antibiotic treatment and outcomes, but the effect of each individual intervention is less clear. The current study investigated the impact of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) versus conventional identification on antibiotic management in a setting with a well-established ASP and low resistance rates.

METHODS: In this single-centre open label, controlled clinical trial 425 patients with positive BCs were allocated by weekday during a 1-year period to either MALDI-TOF directly from positive BCs or conventional processing. ASP was identical throughout the study period. The primary outcome was duration of intravenous antimicrobial therapy and was analysed in an intention-to-treat approach.

RESULTS: In all, 368 patients were analysed (MALDI-TOF n = 168; conventional n = 200) with similar baseline characteristics. Mean duration of intravenous antimicrobial therapy (12.9 versus 13.2 days, p 0.9) and length of stay (16.1 versus 17.9 days, p 0.3) were comparable. In the clinically significant bloodstream infection subgroup (n = 242) mean time from Gram-stain to active treatment was significantly shorter (3.7 versus 6.7 h, p 0.003). Admission to the intensive care unit after bloodstream infection onset was less frequent in the MALDI-TOF group (23.1 versus 37.2%, p 0.02).

CONCLUSIONS: Rapid identification of contaminated BCs (n = 126) resulted in a shorter duration of intravenous antimicrobial therapy (mean 4.8 versus 7.5 days, p 0.04). Rapid identification using MALDI-TOF directly from positive BCs did not impact on duration of intravenous antimicrobial therapy, but provided fast and reliable microbiological results and may improve treatment quality in the setting of an established ASP.