Are We Ready for Nosocomial Infections? Rapid Identification and Antifungal Resistance Detection Using MALDI-TOF Mass Spectrometry May Be the Answer.

The occurrence of multidrug-resistant isolates and the increased mortality associated with invasive infections or outbreaks due to this species have been reported in many healthcare settings. Therefore, accurate and rapid identification at the species level of clinical isolates as well as their timely differentiation as susceptible or resistant to antifungal drugs is mandatory. Aims of the present study were to implement the MALDI-TOF mass spectrometry (MS) Bruker Daltonics Biotyper database with spectrum profiles and to develop a fast and reproducible MS assay for detecting anidulafungin (AFG) resistance in isolates. After creation of main spectra, a score-oriented dendrogram was generated from hierarchical cluster analysis, including spectra of isolates from and other (, , , , and ) or non- () species. Cluster analysis allowed to group and classify the isolates according to their species designation. Then, a three-hour incubation antifungal susceptibility testing (AFST) assay was developed. Spectra obtained at null, intermediate, or maximum AFG concentrations were used to create composite correlation index matrices for eighteen isolates included in the study. All six resistant isolates were detected as resistant whereas 11 of 12 susceptible isolates were detected as susceptible by the MS-AFST assay. In conclusion, our MS-based assay offers the possibility of rapidly diagnosing and appropriately treating patients with infection.