Rapid direct identification of positive paediatric blood cultures by MALDI-TOF MS technology and its clinical impact in the paediatric hospital setting.

Abstract

Objective: Rapid diagnostic tools are imperative for timely clinical decision making, particularly in bacteraemic patients. This study evaluated the performance of a fast, inexpensive novel in house method for processing positive blood cultures for immediate identification of microorganisms by MALDI-TOF mass spectrometry (Vitek MS bioMérieux). We prospectively analyzed the clinical impact of such method on the management of pediatric patients.Result: In total, 360 positive blood cultures were included in this study. Among 318 mono-microbial cultures, in-house method achieved correct identification in 270 (85%) cultures to the species level, whilst 43 (13.5%) gave no identification, and 7 (2.2%) gave discordant identifications. Identification of Gram-negative organisms was accurate to both species and genus level in 99% of isolates, and for Gram positives accuracy was 84% to genus and 81% to species level overall, with accuracy of 100% for Staphylococcus aureus and Enterococcus to the species level. Assessment of the potential impact of direct MALDI-TOF identification in sixty sequential cases revealed a clear clinical benefit in 35.5% of cases. Benefits included timely antibiotic rationalization, change of medical intervention, and early confirmation of contamination. This study demonstrates a highly accurate in-house method with considerable potential clinical benefits for paediatric care.

The value of MALDI-TOF failure to provide an identification of Staphylococcal species direct from blood cultures and rule out Staphylococcus aureus bacteraemia: a post-hoc analysis of the RAPIDO trial

“…Previous research has shown the value of MALDI-TOF in direct identification of blood cultures, showing a significant decrease in time to identification in RAPIDO [3], and with observational data supporting the accuracy and timeliness of direct MALDI-TOF [1,[5][6][7][8][9]. Recent work on SA has shown the potential for rapid identification of methicillin resistance using a directly targeted assay with cefoxitin added to the droplets and incubated before addition of matrix [10].…”

Diagnostic clinical microbiology

“…From agar plates, isolated colonies are chosen for identification. Direct identification from clinical specimens (i.e., blood cultures) has been investigated and is an area of continuing investigation/development (Samaranayake et al, 2020; Schubert et al, 2011). The concept is quite simple and straight forward: that is, bacteria to be identified are placed on a slot on a glass slide to which a matrix solution is added.…”