First description of the performance of the VITEK MITUBE device used with MALDI-TOF mass spectrometry to achieve identification of gram-negative bacteria directly from positive blood culture broth.

Abstract

Improving the rapidity of identification of bacteria causing bacteremia continues to be a focus for quality improvement within the discipline of clinical microbiology. This multicenter study was used to obtain In Vitro Diagnostic Regulation Conformite Europeenne (CE) mark in Europe and describes the performance of the VITEK MITUBE to matrix-assisted laser desorption/ionization (MALDI) workflow for identification of 10 species of gram-negative bacteria directly from positive blood culture broth without subculture. One hundred twenty-five (125) prospective clinical samples, including Escherichia coli (69), Klebsiella aerogenes (4), Klebsiella oxytoca (3), Klebsiella pneumoniae (29), Proteus mirabilis (9), Pseudomonas aeruginosa (10), and Serratia marcescens (1), were included; and 123 (98.4%) were accurately identified using the VITEK MITUBE workflow. None were misidentified, and two (1.6%) K. pneumoniae were not identified. Contrived samples were also tested and reported in this study. When considering both the prospective clinical samples and the contrived samples, the workflow was able to identify the species 95% of the time. Proteus vulgaris accounted for 81% (13/16) of the samples that were unable to achieve an identification. A single misidentification error is reported in the contrived sample testing. The VITEK MITUBE to MALDI workflow enables accurate and reliable identification of commonly encountered gram-negative bacteria directly from positive blood culture broth.IMPORTANCEMITUBE is a new in vitro diagnostic device designed to meet a need in the clinical microbiology community for a simple, rapid, accurate, and inexpensive system to identify bacteria detected in blood cultures using MALDI-TOF and without the need for subculture.