Comparison of the BluePoint MoldID oligonucleotide array and Bruker Biotyper MALDI-TOF MS for the identification of filamentous fungi.

Abstract

BluePoint MoldID can identify 43 fungal species through nucleic acid array hybridization and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) can identify 247 filamentous fungi through mass spectrometry. First, 43 standard isolates from the Bioresource Collection and Research Center, Taiwan, and the College of American Pathologists and 41 clinical Aspergillus species isolates confirmed by rDNA-ITS sequencing were analyzed using BluePoint MoldID and Bruker MALDI-TOF MS. BluePoint MoldID accurately identified 79% (34/43) of the standard isolates to the species level but failed to recognize nine isolates absent from its database; additionally, 87.8% (36/41) of the clinical isolates were identified at the species level, with 80.5% (33/41) accuracy. MALDI-TOF MS identified 86% (37/43) of the standard isolates, with 81.4% (35/43) accurately identified at the species level and two at the genus level, and identified all the clinical isolates, with 92.6% (38/41) accurately identified at the species level. Next, we analyzed 93 clinical Aspergillus species and compared the results by rDNA-ITS sequencing. BluePoint MoldID identified 87.1% (81/93) of the isolates at the species level, with 80.6% (75/93) accuracy. MALDI-TOF MS identified 97.8% (91/93) of the isolates, including some uncommon species, with 90.3% (84/93) accuracy at the species level. BluePoint MoldID and MALDI-TOF MS had turnaround times of 8 and 2 h, respectively, significantly reducing the time needed to identify filamentous fungi.

Importance: The BluePoint MoldID kit is an oligonucleotide array used for the identification of filamentous fungi, and it has not yet been mentioned in recent studies. We used a BluePoint MoldID kit to identify standard and clinical filamentous fungal isolates and compared its performance with that of Bruker MALDI-TOF MS. The former accurately identified 80.2% of the isolates (142/177), and the latter identified 92.6% of the isolates (164/177). The performance of the BluePoint MoldID kit was slightly inferior to that of Bruker MALDI-TOF MS because of the smaller database. However, the BluePoint MoldID kit can cover most clinically common opportunistic fungal infections; thus, it offers an alternative method for laboratories that lack MALDI-TOF MS equipment, as the device is less expensive.