Abstract
ObjectivesRapid and accurate mold identification is critical for guiding therapy for mold infections. MALDI-TOF MS has been widely adopted for bacterial and yeast identification; however, few clinical laboratories have applied this technology for routine mold identification due to limited database availability and lack of standardized processes. Here, we evaluated the versatility of the NIH Mold Database in a multicenter evaluation.MethodsThe NIH Mold Database was evaluated by eight US academic centers using a solid media extraction method and a challenge set of 80 clinical mold isolates. Multiple instrument parameters important for spectra optimization were evaluated, leading to the development of two specialized acquisition programs (NIH method and the Alternate-B method).ResultsA wide range in performance (33–77%) was initially observed across the eight centers when routine spectral acquisition parameters were applied. Use of the NIH or the Alternate-B specialized acquisition programs, which are different than those used routinely for bacterial and yeast spectral acquisition (MBT_AutoX), in combination with optimized instrument maintenance, improved performance, illustrating that acquisition parameters may be one of the key limiting variable in achieving successful performance.ConclusionSuccessful mold identification using the NIH Database for MALDI-TOF MS on Biotyper systems was demonstrated across multiple institutions for the first time following identification of critical program parameters combined with instrument optimization. This significantly advances our potential to implement MALDI-TOF MS for mold identification across many institutions. Because instrument variability is inevitable, development of an instrument performance standard specific for mold spectral acquisition is suggested to improve reproducibility across instruments.
Highlights
MATERIALS AND METHODSRapid bacterial and yeast identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDITOF MS) has revolutionized microbiology laboratory practices (Tan et al, 2012; Huang et al, 2013; Lacroix et al, 2014)
No misidentifications were observed with the NIH Mold Database; a few misidentifications were noted with the Bruker MBT Database (Table 2)
We evaluated the versatility of the NIH Mold Database (Lau et al, 2013) across 10 centers each with varying levels of mass spectrometry experience with molds, using a set of 80 challenge isolates that encompassed common clinical molds and less common organisms (Table 1)
Summary
MATERIALS AND METHODSRapid bacterial and yeast identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDITOF MS) has revolutionized microbiology laboratory practices (Tan et al, 2012; Huang et al, 2013; Lacroix et al, 2014). Studies evaluating MALDI-TOF MS for mold identification have been published, but only a few clinical laboratories have applied this technology in routine practice. Utilize either the Bruker MALDI Biotyper (MBT) system for which the Filamentous Fungal Database has not been cleared by the FDA, or the older VITEK MS 2.0 which lacks the mold database due to the time needed for test system reverification and/or software compatibility restraints. Unlike multicenter bacterial and yeast studies for which excellent inter- and intra-laboratory reproducibility has been demonstrated (Westblade et al, 2015; Wilson et al, 2017), this study has highlighted significant performance variability between instruments regardless of acquisition parameters and demonstrated that development of a specific mold standard is required for successful use of MALDITOF MS for mold identification
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