Evaluation of two commercial kits for rapid pathogen identification directly from positive blood cultures by matrix-associated laser desorption/ionization time-of-flight mass spectrometry

Abstract

Background: A bloodstream infection is a life-threatening medical emergency, with a mortality rate of up to 30%. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) can be used to identify pathogens directly from positive blood cultures. Two commercial preparation kits, SepsiTyper (Bruker Daltonics, Germany) and SepsiPrep (ASTA Corp., Korea), and two MALDI-TOF MS systems, MALDI Biotyper Sirius (Bruker Daltonics, Germany) and VITEK MS PRIME (bioMérieux, France), are available in Korea. We examined these kits and MALDI-TOF MS systems to analyze their performance. Methods: We assessed the effectiveness of direct identification using 47 blood cultures and 3 bile cultures positive for microbial growth. The VIRTUO system (bioMérieux, France) was used to incubate the samples after they were collected in Bact/ALERT aerobic and anaerobic bottles. The manufacturers’ protocols were followed for both the SepsiTyper and SepsiPrep kits. Results: The SepsiTyper yielded considerably more accurate identifications than did the SepsiPrep, when utilized in MALDI-TOF MS systems (P = 0.0044). However, the SepsiPrep was easier to use and the results more quickly obtained than with the SepsiTyper. The MALDI Biotyper Sirius produced more accurate identifications with the SepsiTyper than did the VITEK MS PRIME (P = 0.0736). The SepsiTyper enabled the accurate identification of five of six polymicrobial cases, utilizing either the MALDI-TOF MS systems. Conclusions: Among the pathogen ID kits tested in this study, the SepsiTyper with MALDI Biotyper Sirius performed the best. In clinical laboratories utilizing VITEK MS PRIME, it is recommended that the either the SepsiTyper or SepsiPrep kit be used for direct identification, while considering certain limitations in terms of performance.