A-240 Rapid and Reliable Identification of Microorganisms from Early Growth of Positive Blood Cultures Using MALDI-TOF Mass Spectrometry

Abstract Background Rapid identification of organisms causing bloodstream infections is critical for treatment. Traditional workflows rely on 18–24 h growth isolated colonies. Our objective was to evaluate early using Bruker and VITEK® MS PRIME MALDI-TOF systems. Materials Positive blood cultures (BACT/ALERT® FA/FN Plus; bioMérieux VIRTUO®) were included if bottles positive <8 had time-to-positivity <40 h. Broths sub-cultured agar incubated at 35°C/5% CO2. 6–8 (short incubation, SI) (standard SDI) performed by a high (HEU, >1 year) low (LEU, <1 month) experience user. Each standard set-up VITEK PRIME, target PICKMETM pen. Identification level time-to-result (TTR) measured compared Fisher’s exact t-test. Results 53 (36 Gram-positive, 15 Gram-negative, 2 yeast) from 50 cultures. The HEU achieved species-level 87% routine PICKME after SI vs 74% Bruker, while 66% 70% identified 75% the LEU (Table). After SDI, ≥94%(HEU) ≥87%(LEU) identified, with no differences noted or user (P > 0.05). Species-level higher Gram-negative (100%) Gram-positive (67–86%) HEU. pen usage increased identifications 100% 67% Gram-negatives LEU. For mixed (n = 3), only 1 SI. TTR significantly longer(P < 0.05) SDI Conclusions microorganisms short incubation solid media achieves early, reliable majority without need additional hands-on time extraction.