In this study, a total of 125 clinical fungal culture isolates (yeast and
filamentous fungi) and 9 ATCC controls were analyzed using MALDITOFMS.
Itwas found that all the 9 ATCC reference strainswere correctly
identified byMALDI TOFMSwith a log (score) values of N2.30 indicative
of ‘highly probable species identification’. Upon comparing and analyzing
both the MS fingerprint patterns obtained from 125 isolates with
that from the conventional tests, it was observed that the correlation
in yeast (n = 88) identification was extremely high (100%) both at
the genus and species levels (Table. 1). On the other hand, the correlation
in mold identification was more heterogeneous when the normal
extraction procedure was followed as that of yeast (Table 2). Among
the total 37 mold isolates, only 12 (32.42%) isolates were deemed
“Not Reliable Identification (NRI)”,whereas 4 (10.81%) isolates had correct
identification up to the genus level and the rest 21 (56.7%) isolates
up to both the genus and species levels.
Our modified protocol for sample preparation has significantly improved
the identification of molds by MALDI-TOF MS (Table 3).
Among the total 37 mold isolates, only one isolate (2.7%) was deemed
NRI, whereas 4 (10.8%) isolates had correct identification up to the
genus level only and the rest 32 (86.4%) isolates had correct identification
till the genus and species levels.
The correlation betweenMALDI-TOF MS and conventional identification
for all 125 fungal isolates included in the study was 96%
((88 + 32) / 125) at the species level and 99.2% ((88 + 32 + 4) / 125)
at the genus level. Only 2.7% isolates (1/125) had NRI when compared
to conventional methods of identification. The spectral processing