Etest and Sensititre YeastOne Susceptibility Testing of Echinocandins against Candida Species from a Single Center in Austria

Abstract

Candida species were tested for susceptibility to caspofungin, anidulafungin, and micafungin in order to evaluate the roles of Etest and Sensititre YeastOne in antifungal susceptibility testing for daily routines and to survey resistance. A total of 104 Candida species isolates detected from blood cultures were investigated. With EUCAST broth microdilution as the reference method, essential agreement (EA), categorical agreement (CA), very major errors (VME), major errors (ME), and minor (MIN) errors were assessed by reading MICs at 18, 24, and 48 h. By use of EUCAST broth microdilution and species-specific clinical breakpoints (CBPs), echinocandin resistance was not detected during the study period. Using EUCAST CBPs, MIC readings at 24 h for the Etest and Sensititre YeastOne resulted in CA levels of 99% and 93% for anidulafungin and 99% and 97% for micafungin. Using revised CLSI CBPs for caspofungin, CA levels were 92% and 99% for Etest and Sensititre YeastOne. The Etest proved an excellent, easy-to-handle alternative method for testing susceptibility to anidulafungin and micafungin. Due to misclassifications, the Etest is less suitable for testing susceptibility to caspofungin (8% of isolates falsely tested resistant). The CA levels of Sensititre YeastOne were 93% and 97% for anidulafungin and micafungin (24 h) by use of EUCAST CBPs and increased to 100% for both antifungals if CLSI CBPs were applied and to 100% and 99% if Sensititre YeastOne epidemiological cutoff values (ECOFFs) were applied. No one echinocandin could be demonstrated to be superior to another in vitro. Since resistance was lacking among our Candida isolates, we cannot derive any recommendation from accurate resistance detection by the Etest and Sensititre YeastOne.

Antibacterial and Antifungal Activity of Propyl-Propane-Thiosulfinate and Propyl-Propane-Thiosulfonate, Two Organosulfur Compounds from Allium cepa: In Vitro Antimicrobial Effect via the Gas Phase

“…In this context, the thiosulfinates derived from Allium spp., such as allicin, have demonstrated broad antifungal activity in numerous in vitro studies against yeasts of the genus Candida [ 21 , 22 , 23 ]. In the present work, the MICs obtained for antifungals were similar to those obtained in previous research, both in our geographical area [ 24 , 25 ] and in more remote areas [ 19 , 26 , 27 , 28 , 29 ]. The lowest MICs were obtained for C. albicans and C. tropicalis ; the highest for C. glabrata and C. krusei , especially in the case of azoles, which indicates that Candida species remain susceptible to commonly used antifungals and do not represent a problem for the therapeutic approach.…”

Antifungal susceptibility of yeast bloodstream isolates collected during a 10‐year period in Austria

“…Thus, routine analysis is often performed with the aid of easier‐to‐conduct commercial methods, such as Etest, disc diffusion assays, Sensititre ® , Micronaut ® or Vitek ® , which each have their individual disadvantages . Although commercial systems produce data essentially in agreement with the EUCAST method for azoles and echinocandins, certain pitfalls, such as unclear inhibition zones, remain. In addition, fungi occasionally show distorted growth and thus render interpretation of endpoints difficult.…”

A nationwide passive surveillance on fungal infections shows a low burden of azole resistance in molds and yeasts in Tyrol, Austria

“…Susceptibility tests were performed by applying the Etest ® method to determine the MICs of the respective antifungal agents; in uncertain cases, the EUCAST methodology was applied [ 5 , 6 ]. This commercially available test was previously described as a simple and reliable method for AST that was comparable in performance to reference procedures [ 7 ].…”