Antifungal susceptibility testing of dermatophytes: Development and evaluation of an optimised broth microdilution method

Mycoses ◽  
2020 ◽  
Author(s):  
Riccardo Curatolo ◽  
Nada Juricevic ◽  
Cheryl Leong ◽  
Philipp P. Bosshard
Keyword(s):  
Susceptibility Testing ◽  
Antifungal Susceptibility ◽  
Antifungal Susceptibility Testing ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method

scholarly journals Flow Cytometry Antifungal Susceptibility Testing of Pathogenic Yeasts other than Candida albicans and Comparison with the NCCLS Broth Microdilution Test

2000 ◽  
Vol 44 (10) ◽  
pp. 2752-2758 ◽  
Author(s):  
Rama Ramani ◽  
Vishnu Chaturvedi
Keyword(s):  
Flow Cytometry ◽  
Candida Albicans ◽  
Amphotericin B ◽  
Susceptibility Testing ◽  
Antifungal Susceptibility ◽  
Antifungal Susceptibility Testing ◽  
Broth Microdilution ◽  
Nitrogen Base ◽  
Microdilution Method ◽  
Broth Microdilution Method

ABSTRACT Candida species other than Candida albicansfrequently cause nosocomial infections in immunocompromised patients. Some of these pathogens have either variable susceptibility patterns or intrinsic resistance against common azoles. The availability of a rapid and reproducible susceptibility-testing method is likely to help in the selection of an appropriate regimen for therapy. A flow cytometry (FC) method was used in the present study for susceptibility testing ofCandida glabrata, Candida guilliermondii,Candida krusei, Candida lusitaniae,Candida parapsilosis, Candida tropicalis, andCryptococcus neoformans based on accumulation of the DNA binding dye propidium iodide (PI). The results were compared with MIC results obtained for amphotericin B and fluconazole using the NCCLS broth microdilution method (M27-A). For FC, the yeast inoculum was prepared spectrophotometrically, the drugs were diluted in either RPMI 1640 or yeast nitrogen base containing 1% dextrose, and yeast samples and drug dilutions were incubated with amphotericin B and fluconazole, respectively, for 4 to 6 h. Sodium deoxycholate and PI were added at the end of incubation, and fluorescence was measured with a FACScan flow cytometer (Becton Dickinson). The lowest drug concentration that showed a 50% increase in mean channel fluorescence compared to that of the growth control was designated the MIC. All tests were repeated once. The MICs obtained by FC for all yeast isolates except C. lusitaniae were in very good agreement (within 1 dilution) of the results of the NCCLS broth microdilution method. Paired ttest values were not statistically significant (P = 0.377 for amphotericin B; P = 0.383 for fluconazole). Exceptionally, C. lusitaniae isolates showed higher MICs (2 dilutions or more) than in the corresponding NCCLS broth microdilution method for amphotericin B. Overall, FC antifungal susceptibility testing provided rapid, reproducible results that were statistically comparable to those obtained with the NCCLS method.

Susceptibility of Filamentous Fungi to Voriconazole in Malaysia Tested by Sensititre YeastOne and CLSI Microdilution Methods

2021 ◽  
Author(s):  
Xue Ting Tan ◽  
Stephanie Jane Ginsapu ◽  
Fairuz binti Amran ◽  
Salina binti Mohamed Sukur ◽  
Surianti binti Shukor
Keyword(s):  
Filamentous Fungi ◽  
Susceptibility Testing ◽  
Rhizopus Oryzae ◽  
Antifungal Susceptibility ◽  
Sporothrix Schenckii ◽  
Rank Test ◽  
Broth Microdilution ◽  
Syncephalastrum Racemosum ◽  
Microdilution Method ◽  
Broth Microdilution Method

Abstract Background: Voriconazole is a trizaole antifungal to treat fungal infection. In this study, the susceptibility pattern of voriconazole against filamentous fungi was studied using Sensititre® YeastOne and Clinical & Laboratory Standards Institute (CLSI) M38 broth microdilution method. Methods: The suspected cultures of Aspergillus niger, A. flavus, A. fumigatus, A. versicolor, A. sydowii, A. calidoutus, A. creber, A. ochraceopetaliformis, A. tamarii, Fusarium solani, F. longipes, F. falciferus, F. keratoplasticum, Rhizopus oryzae, R. delemar, R. arrhizus, Mucor sp., Poitrasia circinans, Syncephalastrum racemosum and Sporothrix schenckii were received from hospitals. Their identification had been confirmed in our lab and susceptibility tests were performed using Sensititre® YeastOne and CLSI M38 broth microdilution method. The significant differences between two methods were calculated using Wilcoxon Sign Rank test.Results: Mean of the minimum inhibitory concentrations (MIC) for Aspergillus spp. and Fusarium were within 0.25 μg/mL-2.00 μg/mL by two methods except A. calidoutus, F. solani and F. keratoplasticum. Moreover, mean of MIC for S. schenkii were around 3.00 μg/mL by two methods. In contrast, mean of MIC for Rhizopus spp., Mucor sp., P. circinans and S. racemosum were ≥6.00 μg/mL by two methods. Generally, the MIC obtained by Sensititre YeastOne was one two-fold increase or decrease compared with the results obtained by CLSI method. The overall agreement between Sensititre YeastOne and CLSI methods to test susceptibility testing of voricaonazole was more than 70% except A. sydowii. The significant differences between two methods were significant when tested on A. niger, A. flavus, A. fumigatus, A. versicolor, A. sydowii, F. solani and S. schenkii. Conclusions: In conclusion, Sensititre YeastOne method appears to be an alternative procedure for antifungal susceptibility testing for some Malaysian moulds.

scholarly journals Evaluation of a Modified EUCAST Fragmented-Mycelium Inoculum Method forIn VitroSusceptibility Testing of Dermatophytes and the Activity of Novel Antifungal Agents

2015 ◽  
Vol 59 (6) ◽  
pp. 3675-3682 ◽  
Author(s):  
B. Risslegger ◽  
C. Lass-Flörl ◽  
G. Blum ◽  
M. Lackner
Keyword(s):  
Antifungal Agents ◽  
Susceptibility Testing ◽  
Preparation Method ◽  
Antifungal Susceptibility ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Inoculum Preparation ◽  
Minimal Effective Concentration

ABSTRACTFor antifungal susceptibility testing of nonsporulating or poorly sporulating dermatophytes, a fragmented-mycelium inoculum preparation method was established and compared to broth microdilution testing according to CLSI and EUCAST guidelines. Moreover, thein vitroactivity of new antifungal agents against dermatophytes was evaluated. Agreement between the mycelial inoculum method and the CLSI broth microdilution method was high (93% to 100%). Echinocandins (minimal effective concentration [MEC], ≤0.5 mg/liter) and posaconazole (MIC, ≤3.00 mg/liter) showed good activity against all tested dermatophytes.

scholarly journals Antifungal Susceptibility Testing of Malassezia spp. with an Optimized Colorimetric Broth Microdilution Method

2017 ◽  
Vol 55 (6) ◽  
pp. 1883-1893 ◽  
Author(s):  
Cheryl Leong ◽  
Antonino Buttafuoco ◽  
Martin Glatz ◽  
Philipp P. Bosshard
Keyword(s):  
Susceptibility Testing ◽  
Skin Diseases ◽  
Antifungal Susceptibility ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Broth Microdilution ◽  
Content Type ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Colorimetric Indicator

ABSTRACTMalasseziais a genus of lipid-dependent yeasts. It is associated with common skin diseases such as pityriasis versicolor and atopic dermatitis and can cause systemic infections in immunocompromised individuals. Owing to the slow growth and lipid requirements of these fastidious yeasts, convenient and reliable antifungal drug susceptibility testing assays forMalasseziaspp. are not widely available. Therefore, we optimized a broth microdilution assay for the testing ofMalasseziathat is based on the CLSI and EUCAST assays forCandidaand other yeasts. The addition of ingredients such as lipids and esculin provided a broth medium formulation that enabled the growth of allMalasseziaspp. and could be read, with the colorimetric indicator resazurin, by visual and fluorescence readings. We tested the susceptibility of 52 strains of 13Malasseziaspecies to 11 commonly used antifungals. MIC values determined by visual readings were in good agreement with MIC values determined by fluorescence readings. The lowest MICs were found for the azoles itraconazole, posaconazole, and voriconazole, with MIC90values of 0.03 to 1.0 μg/ml, 0.06 to 0.5 μg/ml, and 0.03 to 2.0 μg/ml, respectively. AllMalasseziaspp. were resistant to echinocandins and griseofulvin. SomeMalasseziaspp. also showed high MIC values for ketoconazole, which is the most widely recommended topical antifungal to treatMalasseziaskin infections. In summary, our assay enables the fast and reliable susceptibility testing ofMalasseziaspp. with a large panel of different antifungals.

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