Abstract

Background: The introduction of MALDI-TOF MS, BD PHOENIX, and VITEK-2
equipment into the clinical microbiology laboratory has changed the techniques of
fungal identification. This technique can be used to find cryptic species that have
critical susceptibility patterns. The MALDI-TOF MS, BD PHOENIX, and VITEK-2
systems were used to identify clinical strains. Assuming MALDI-TOF MS isolate
identification as standard, discrepancies between three approaches were evaluated.
Finally, these isolates were subjected to in vitro susceptibility testing.
Results: The agreement between the two approaches for 498 yeast isolates was 93.6
percent (32 discrepant isolates). The BD PHOENIXconcordance with VITEK-2 systems
was lower than MALDI-TOF MS. Several of these discordant yeasts had high
antifungal agent MICs.
Conclusions: We discovered the unusual yeasts, including Candida auris, Trichosporon
faecalis and other yeasts. Although not totally satisfying, the performance of the BD
Phoenix system was superior to that of the Vitek 2 system, particularly its performance
with yeast species that are infrequently isolated in the clinical context. Although new
and promising molecular methods such as MALDI-TOF MS are now available, many
clinical microbiology laboratories continue to rely on instruments such as the BD
Phoenix and Vitek 2 for routine identification of fungal agents.