Evaluation of the clinical application of MALDI-TOF MS with directly smeared target in rapid identification of filamentous fungi

ObjectiveTo evaluate the clinical application of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) with directly smeared target (MS direct smear method) in the rapid identification of filamentous fungi.

MethodsA study was performed on 133 strains of filamentous fungi cultured from clinical samples in Beijing Tongren Hospital affiliated to Capital Medical University from January 2010 to December 2017, and these strains were identified by morphological observation, gene sequence analysis and MS direct smear method, respectively. The results were analyzed and compared. χ² test was performed in the enumeration data analysis by using software SPSS 16.0.

ResultsBased on the results of 133 strains of filamentous fungi identified by gene sequence analysis and morphological observation, the identification rates of species, complex and genera of the filamentous fungi strains by MS direct smear method were 64.66%, 79.70% and 96.24%, respectively, while the rates obtained by gene sequence analysis were 69.17%, 83.46% and 99.25%, respectively, and then the rates by morphological identification were 68.42%, 84.21% and 93.23%, respectively. Furthermore, there were no significant differences in the identification rates of the species, complexes and genera between MS direct smear method and latter two methods (χ²＝0.611, 0.625, 2.728, respectively, and χ²＝0.516, 0.915, 1.206, respectively, P＞0.05). MS direct smear method identified 61.04%, 88.31% and 98.70% of the 77 strains of Aspergillus, respectively, at species, complex and genera levels, 64.29% and 92.86% of the 14 strains of Penicillium at species and genera levels, and 71.43% and 92.86% of 42 other filamentous fungi strains at species and genera levels. Five strains (3.76%, 5/133) were not identified due to the insufficient species of fungi in the database.

ConclusionMALDI-TOF MS with directly smeared target can accurately identify clinical filamentous fungi with similar results to morphological observation and gene sequence analysis. It is the test which is rapid, easy and simple to handle for use in clinical practice.