TY - JOUR

T1 - Quality of MALDI-TOF mass spectra in routine diagnostics

T2 - results from an international external quality assessment including 36 laboratories from 12 countries using 47 challenging bacterial strains

AU - Cuénod, Aline

AU - Aerni, Martina

AU - Bagutti, Claudia

AU - Bayraktar, Banu

AU - Boz, Efe Serkan

AU - Carneiro, Cynthia Beisert

AU - Casanova, Carlo

AU - Coste, Alix T.

AU - Damborg, Peter

AU - van Dam, Dirk W.

AU - Demirci, Mehmet

AU - Drevinek, Pavel

AU - Dubuis, Olivier

AU - Fernandez, José

AU - Greub, Gilbert

AU - Hrabak, Jaroslav

AU - Hürkal Yiğitler, Gülen

AU - Hurych, Jakub

AU - Jensen, Thøger Gorm

AU - Jost, Géraldine

AU - Kampinga, Greetje A.

AU - Kittl, Sonja

AU - Lammens, Christine

AU - Lang, Claudia

AU - Lienhard, Reto

AU - Logan, Julie

AU - Maffioli, Carola

AU - Mareković, Ivana

AU - Marschal, Matthias

AU - Moran-Gilad, Jacob

AU - Nolte, Oliver

AU - Oberle, Michael

AU - Pedersen, Michael

AU - Pflüger, Valentin

AU - Pranghofer, Sigrid

AU - Reichl, Julia

AU - Rentenaar, Rob J.

AU - Riat, Arnaud

AU - Rodríguez-Sánchez, Belén

AU - Schilt, Camille

AU - Schlotterbeck, Ann Kathrin

AU - Schrenzel, Jacques

AU - Troib, Shani

AU - Willems, Elise

AU - Wootton, Mandy

AU - Ziegler, Dominik

AU - Egli, Adrian

AU - for the ESGMD study group

N1 - Publisher Copyright: © 2022 The Authors

PY - 2023

Y1 - 2023

N2 - Objectives: Matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) is a widely used method for bacterial species identification. Incomplete databases and mass spectral quality (MSQ) still represent major challenges. Important proxies for MSQ are the number of detected marker masses, reproducibility, and measurement precision. We aimed to assess MSQs across diagnostic laboratories and the potential of simple workflow adaptations to improve it. Methods: For baseline MSQ assessment, 47 diverse bacterial strains, which are challenging to identify by MALDI-TOF MS, were routinely measured in 36 laboratories from 12 countries, and well-defined MSQ features were used. After an intervention consisting of detailed reported feedback and instructions on how to acquire MALDI-TOF mass spectra, measurements were repeated and MSQs were compared. Results: At baseline, we observed heterogeneous MSQ between the devices, considering the median number of marker masses detected (range = [2–25]), reproducibility between technical replicates (range = [55%–86%]), and measurement error (range = [147 parts per million (ppm)–588 ppm]). As a general trend, the spectral quality was improved after the intervention for devices, which yielded low MSQs in the baseline assessment as follows: for four out of five devices with a high measurement error, the measurement precision was improved (p-values <0.001, paired Wilcoxon test); for six out of ten devices, which detected a low number of marker masses, the number of detected marker masses increased (p-values <0.001, paired Wilcoxon test). Discussion: We have identified simple workflow adaptations, which, to some extent, improve MSQ of poorly performing devices and should be considered by laboratories yielding a low MSQ. Improving MALDI-TOF MSQ in routine diagnostics is essential for increasing the resolution of bacterial identification by MALDI-TOF MS, which is dependent on the reproducible detection of marker masses. The heterogeneity identified in this external quality assessment (EQA) requires further study.

AB - Objectives: Matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) is a widely used method for bacterial species identification. Incomplete databases and mass spectral quality (MSQ) still represent major challenges. Important proxies for MSQ are the number of detected marker masses, reproducibility, and measurement precision. We aimed to assess MSQs across diagnostic laboratories and the potential of simple workflow adaptations to improve it. Methods: For baseline MSQ assessment, 47 diverse bacterial strains, which are challenging to identify by MALDI-TOF MS, were routinely measured in 36 laboratories from 12 countries, and well-defined MSQ features were used. After an intervention consisting of detailed reported feedback and instructions on how to acquire MALDI-TOF mass spectra, measurements were repeated and MSQs were compared. Results: At baseline, we observed heterogeneous MSQ between the devices, considering the median number of marker masses detected (range = [2–25]), reproducibility between technical replicates (range = [55%–86%]), and measurement error (range = [147 parts per million (ppm)–588 ppm]). As a general trend, the spectral quality was improved after the intervention for devices, which yielded low MSQs in the baseline assessment as follows: for four out of five devices with a high measurement error, the measurement precision was improved (p-values <0.001, paired Wilcoxon test); for six out of ten devices, which detected a low number of marker masses, the number of detected marker masses increased (p-values <0.001, paired Wilcoxon test). Discussion: We have identified simple workflow adaptations, which, to some extent, improve MSQ of poorly performing devices and should be considered by laboratories yielding a low MSQ. Improving MALDI-TOF MSQ in routine diagnostics is essential for increasing the resolution of bacterial identification by MALDI-TOF MS, which is dependent on the reproducible detection of marker masses. The heterogeneity identified in this external quality assessment (EQA) requires further study.

KW - Bacterial species identification

KW - Diagnostic performance external quality assessment

KW - MALDI-TOF MS

KW - Quality control

KW - Standardisation

U2 - 10.1016/j.cmi.2022.05.017

DO - 10.1016/j.cmi.2022.05.017

M3 - Journal article

C2 - 35623578

AN - SCOPUS:85134840447

VL - 29

SP - 190

EP - 199

JO - Clinical Microbiology and Infection

JF - Clinical Microbiology and Infection

SN - 1198-743X

IS - 2

ER -