Validation of the Colibrí Instrument for Automated Preparation of MALDI-TOF MS Targets for Yeast Identification


Recently, Copan (Italy) introduced the Colibrí instrument for automated colony
picking and preparation of matrix-assisted laser desorption ionization–time of flight (MALDI- TOF)
target plates. Our study aimed to validate this system for yeasts as such testing has not been
performed yet and is a missing link needed to implement the system for routine use. Fifty-five
Candida strains were selected to evaluate the accuracy of Colibrí. For each strain, a sheep blood
agar plate supplemented with X and V factors (HEM) and a Sabouraud agar plate (SAB) were inoculated
and incubated using the WASPlab specimen processing system (Copan). After 18 h and 36 h of
incubation, the isolates were spotted in parallel using Colibrí and manually onto MALDI-TOF target
plates with the addition of formic acid and identified using MALDI-TOF mass spectrometry. The
reproducibility was evaluated using ATCC reference and clinical isolate-derived strains. The
cumulative percentage of accept- able identification scores (IDs) after 36 h was 91% for strains
cultured on HEM plates using both Colibrí and the manual method. The SAB plates showed inferior
results for both Colibrí (76%) and the manual method (78%). We observed an overall agreement of 92%
at 18 h for identification of the strains on the HEM plates between Colibrí and the manual method
and 94% after 36 h. For the SAB plates, the agreement was 78% after 18 h and 84% after 36 h. Apart
from Candida dubliniensis and Candida tropicalis, all Candida species were identified with 100%
accuracy using Colibrí on HEM plates. We observed good agreement between Colibrí and the manual
reference method. These results demonstrate that Colibrí is a reliable system for MALDI-TOF target
preparation for yeast identification, allowing increased standardization and less hands-on time.