Evaluation of the Vitek-MS™ system in the identification of Candida isolates from bloodstream infections

Abstract

Background: Matrix-assisted laser desorption-time of flight mass spectrometry (MALDI-TOF-MS) represents a revolution in the identification of microorganisms of clinical interest. Many studies have confirmed the accuracy and fastness of this tool with routine strains.

Aims: To identify clinical isolates of Candida from patients diagnosed with candidemia.

Methods: Vitek-MS™ system was used with a collection of 298 blood isolates of the genus Candida represented by 9 different species. Sequencing of the internal transcribed spacer (ITS) region of ribosomal DNA cluster was used as the reference method.

Results: The results of Vitek-MS™ were concordant with those obtained with the reference method for 279 (93.62%) isolates (Kappa coefficient (κ)=0.91). Vitek-MS™ misidentified 10 (3.36%) isolates and did not identify 9 (3.02%) isolates.

Conclusions: This study determines the potential of Vitek-MS™ in yeast identification, being a reliable and fast alternative in the clinical laboratory, with an acceptable sensitivity of 82% (IC 95%: 70-90.6%), in comparison with a 100% (IC 95%: 92.9-100%) sensitivity of the conventional methods.

Keywords: Candida spp.; Especificidad; MALDI-TOF MS; MALDI-TOF-MS; Sensibilidad; Sensitivity; Specificity; VITEK(®) MS; Vitek-MS™.