Single-Cell Optical Nanomotion of Candida albicans in Microwells for Rapid Antifungal Susceptibility Testing

Abstract

Candida albicans is an emerging multidrug-resistant opportunistic pathogen representing an important source of invasive disease in humans and generating high healthcare costs worldwide. The development of a rapid and simple antifungal susceptibility test (AFST) could limit the spread of this disease, increase the efficiency of treatment, and lower the risk of developing resistant strains. We developed a microfluidic chip containing an array of microwells that were designed to trap the cells and perform rapid antifungal susceptibility tests using optical nanomotion detection (ONMD). Yeast cell entrapment in a microwell allows for a very rapid exchange of growth medium with the antifungal, which enables performing single-cell ONMD measurements on the same cell before and after antifungal treatment. The exposure to a low concentration of the antifungal caspofungin or flucanozole induced a significant decrease in the nanomotion signal, demonstrating the high sensitivity of this technique. We used this chip to quantify the real-time response of individual C. albicans cells to the antifungal treatment in as fast as 10 min. This simple and label-free technique could be further developed into a simple-to-use device that allows the performance of fast AFST as part of a routine hospital procedure in developed and also eventually developing world countries.

Yeast Biotechnology 6.0

“…Radonicic et al [14] developed a rapid antifungal susceptibility testing (AFST) method based on optical nanomotion detection (ONMD) and applied it to the opportunistic fungal pathogen Candida albicans. In ONMD, an optical microscope is used to record the nanometric-scale movements of living cells.…”

A simplified version of rapid susceptibility testing of bacteria and yeasts using optical nanomotion detection

“…Since it does not require the attachment of the cells to a cantilever and is a single-cell technique, it is much simpler to implement and significantly cheaper than its AFM-based ancestor. ONMD was shown to be an efficient and rapid AST method that can be applied to motile, non-motile, Gram-positive, Gram-negative, rapid, and slow-growing bacteria ( Villalba et al, 2023 ) and yeast cells (such as Candida species) ( Willaert et al, 2020 ; Radonicic et al, 2022 , 2023 ).…”

Machine learning method for the classification of the state of living organisms’ oscillations

“…One of the primary and most straightforward applications is the development of rapid and label-free antimicrobial sensitivity tests for pathogenic bacteria (or yeasts) ( Stupar et al, 2017 ; Mustazzolu et al, 2019 ; Villalba et al, 2022 ; 2023 ; Radonicic et al, 2023 ). In this approach, the organism of interest is exposed to different antibiotics, and its nanomotion is monitored over time.…”