Susceptibility Testing of Fungi to Antifungal Drugs

Abstract

Susceptibility testing of fungi against antifungal drugs commonly used for therapy is a key component of the care of patients with invasive fungal infections. Antifungal susceptibility testing (AFST) has progressed in recent decades to finally become standardized and available as both Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) reference methods and in commercial manual/automated phenotypic methods. In clinical practice, the Sensititre YeastOne and Etest methods are widely used for AFST, particularly for sterile site isolates of Candida. Nevertheless, AFST is moving toward new phenotypic methods, such as matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), that are capable of providing rapid, and potentially more actionable, results for the treating clinician. Our objective is to summarize updated data on phenotypic methods for AFST of Candida and Aspergillus species and to assess their significance in view of opposing, but emerging, molecular genotypic methods.

Antimicrobial Susceptibility Testing of Antimicrobial Peptides to Better Predict Efficacy

“…Different documents describe breakpoints for bacteria, yeasts, filamentous fungi (moulds) and other microorganisms ( Table 1 ). Despite many similarities and agreements, there remains some lack of harmonisation between AST methods from different organisations (Pfaller et al, 2011 , 2014 ; Chowdhary et al, 2015 ; Kahlmeter, 2015 ; Brown et al, 2016 ; Sanguinetti and Posteraro, 2018 ; Simjee et al, 2018 ; Cusack et al, 2019 ). Interpretive categories most commonly assigned are susceptible (S), indicative of a high probability of a successful outcome, and resistant (R), indicative of a low probability of a successful outcome, although in less common cases other categories include; non-susceptible, intermediate, susceptible-dose dependent and area of technical uncertainty (See the documents in Table 1 for details about these interpretive categories).…”

“…Antimicrobial susceptibility testing (AST) determines the concentration of an antimicrobial that inhibits microbial growth, for both microbicidal and microbiostatic agents (Brown et al, 2016 ; Sanguinetti and Posteraro, 2018 ; Humphries et al, 2019 ; van Belkum et al, 2019 ). The importance of accurate AST in at least guiding antibiotic use in the clinic cannot be underestimated (Doern et al, 1994 ; Kumar et al, 2009 ; Weiss et al, 2012 ; Holmes et al, 2016 ).…”

Antimicrobial Activity and Interactions of Toddalia asiatica Isolated Coumarins with Two Known Drugs

“…A number of phytochemicals have proven therapeutic potential as antimicrobial compounds and have also been shown to increase the susceptibility of the organism to various drugs [28,29,31]. In the current study, interaction in antimicrobial activity between two isolated compounds 1 and 3, and in combination with antimicrobial agents, gentamycin and fluconazole was evident.…”

“…The minimum inhibitory concentrations (MICs) of test samples and the positive control drugs gentamicin (1.0 µg/disc) and fluconazole (1.0 µg/disc) were measured by the microdilution broth susceptibility assay Sanguinetti, & Posteraro, [31] against the microorganisms S. aureus, E. coli, P. digitatum and R. stolonifer, obtained from MMUST microbiology laboratory. The inocula of bacterial strains were prepared from 12 h broth cultures and suspensions were adjusted to 0.5 McFarland standard turbidity.…”

Invasive Candidiasis: Epidemiology and Risk Factors

“…Examples include Sensititre™ and YeastOne™. Other methods are based on agar, in which a gradient of the antifungal is diffused in the solid growth media, which allows to directly read the MIC (e.g., Etest ™) [7].…”