Evaluation of Etest and MICRONAUT-AM Assay for Antifungal Susceptibility Testing of <i>Candida auris</i>: Underestimation of Fluconazole Resistance by MICRONAUT-AM and Overestimation of Amphotericin B Resistance by Etest
Multidrug-resistant <i>Candida auris</i> has recently caused major outbreaks in healthcare facilities. Rapid and accurate antifungal susceptibility testing (AST) of <i>C. auris</i> is crucial for proper management of invasive infections. The Commercial Sensititre Yeast One an...
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2024-09-01
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| author | Mohammad Asadzadeh Suhail Ahmad Wadha Alfouzan Inaam Al-Obaid Bram Spruijtenburg Eelco F. J. Meijer Jacques F. Meis Eiman Mokaddas |
| author_facet | Mohammad Asadzadeh Suhail Ahmad Wadha Alfouzan Inaam Al-Obaid Bram Spruijtenburg Eelco F. J. Meijer Jacques F. Meis Eiman Mokaddas |
| author_sort | Mohammad Asadzadeh |
| collection | DOAJ |
| description | Multidrug-resistant <i>Candida auris</i> has recently caused major outbreaks in healthcare facilities. Rapid and accurate antifungal susceptibility testing (AST) of <i>C. auris</i> is crucial for proper management of invasive infections. The Commercial Sensititre Yeast One and Vitek 2 methods underestimate or overestimate the resistance of <i>C. auris</i> to fluconazole and amphotericin B (AMB). This study evaluated the AST results of <i>C. auris</i> against fluconazole and AMB by gradient-MIC-strip (Etest) and broth microdilution-based MICRONAUT-AM-EUCAST (MCN-AM) assays. Clinical <i>C. auris</i> isolates (<i>n</i> = 121) identified by phenotypic and molecular methods were tested. Essential agreement (EA, ±1 two-fold dilution) between the two methods and categorical agreement (CA) based on the Centers for Disease Control and Prevention’s (CDC’s) tentative resistance breakpoints were determined. Fluconazole resistance-associated mutations were detected by PCR-sequencing of <i>ERG11</i>. All isolates identified as <i>C. auris</i> belonged to South Asian clade I and contained the <i>ERG11</i> Y132F or K143R mutation. The Etest–MCN-AM EA was poor (33%) for fluconazole and moderate (76%) for AMB. The CA for fluconazole was higher (94.2%, 7 discrepancies) than for AMB (91.7%, 10 discrepancies). Discrepancies were reduced when an MCN-AM upper-limit value of 4 µg/mL for fluconazole-susceptible <i>C. auris</i> and an Etest upper-limit value of 8 µg/mL for the wild type for AMB were used. Our data show that resistance to fluconazole was underestimated by MCN-AM, while resistance to AMB was overestimated by Etest when using the CDC’s tentative resistance breakpoints of ≥32 µg/mL for fluconazole and ≥2 µg/mL for AMB. Method-specific resistance breakpoints should be devised for accurate AST of clinical <i>C. auris</i> isolates for proper patient management. |
| format | Article |
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| issn | 2079-6382 |
| language | English |
| publishDate | 2024-09-01 |
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| spelling | doaj-art-7c5719fab4ef49e1b71fc2246cbf7b8b2025-08-20T01:56:04ZengMDPI AGAntibiotics2079-63822024-09-0113984010.3390/antibiotics13090840Evaluation of Etest and MICRONAUT-AM Assay for Antifungal Susceptibility Testing of <i>Candida auris</i>: Underestimation of Fluconazole Resistance by MICRONAUT-AM and Overestimation of Amphotericin B Resistance by EtestMohammad Asadzadeh0Suhail Ahmad1Wadha Alfouzan2Inaam Al-Obaid3Bram Spruijtenburg4Eelco F. J. Meijer5Jacques F. Meis6Eiman Mokaddas7Department of Microbiology, Faculty of Medicine, Kuwait University, Safat 13110, KuwaitDepartment of Microbiology, Faculty of Medicine, Kuwait University, Safat 13110, KuwaitDepartment of Microbiology, Faculty of Medicine, Kuwait University, Safat 13110, KuwaitMicrobiology Department, Al-Sabah Hospital, Shuwaikh 70031, KuwaitCanisius Wilhelmina Hospital (CWZ)/Dicoon, 6532 Nijmegen, The NetherlandsCanisius Wilhelmina Hospital (CWZ)/Dicoon, 6532 Nijmegen, The NetherlandsRadboudumc-CWZ Center of Expertise for Mycology, 6500 Nijmegen, The NetherlandsDepartment of Microbiology, Faculty of Medicine, Kuwait University, Safat 13110, KuwaitMultidrug-resistant <i>Candida auris</i> has recently caused major outbreaks in healthcare facilities. Rapid and accurate antifungal susceptibility testing (AST) of <i>C. auris</i> is crucial for proper management of invasive infections. The Commercial Sensititre Yeast One and Vitek 2 methods underestimate or overestimate the resistance of <i>C. auris</i> to fluconazole and amphotericin B (AMB). This study evaluated the AST results of <i>C. auris</i> against fluconazole and AMB by gradient-MIC-strip (Etest) and broth microdilution-based MICRONAUT-AM-EUCAST (MCN-AM) assays. Clinical <i>C. auris</i> isolates (<i>n</i> = 121) identified by phenotypic and molecular methods were tested. Essential agreement (EA, ±1 two-fold dilution) between the two methods and categorical agreement (CA) based on the Centers for Disease Control and Prevention’s (CDC’s) tentative resistance breakpoints were determined. Fluconazole resistance-associated mutations were detected by PCR-sequencing of <i>ERG11</i>. All isolates identified as <i>C. auris</i> belonged to South Asian clade I and contained the <i>ERG11</i> Y132F or K143R mutation. The Etest–MCN-AM EA was poor (33%) for fluconazole and moderate (76%) for AMB. The CA for fluconazole was higher (94.2%, 7 discrepancies) than for AMB (91.7%, 10 discrepancies). Discrepancies were reduced when an MCN-AM upper-limit value of 4 µg/mL for fluconazole-susceptible <i>C. auris</i> and an Etest upper-limit value of 8 µg/mL for the wild type for AMB were used. Our data show that resistance to fluconazole was underestimated by MCN-AM, while resistance to AMB was overestimated by Etest when using the CDC’s tentative resistance breakpoints of ≥32 µg/mL for fluconazole and ≥2 µg/mL for AMB. Method-specific resistance breakpoints should be devised for accurate AST of clinical <i>C. auris</i> isolates for proper patient management.https://www.mdpi.com/2079-6382/13/9/840<i>Candida auris</i>antifungal susceptibility testingEtestMICRONAUT-AM EUCAST assaycomparative performance |
| spellingShingle | Mohammad Asadzadeh Suhail Ahmad Wadha Alfouzan Inaam Al-Obaid Bram Spruijtenburg Eelco F. J. Meijer Jacques F. Meis Eiman Mokaddas Evaluation of Etest and MICRONAUT-AM Assay for Antifungal Susceptibility Testing of <i>Candida auris</i>: Underestimation of Fluconazole Resistance by MICRONAUT-AM and Overestimation of Amphotericin B Resistance by Etest Antibiotics <i>Candida auris</i> antifungal susceptibility testing Etest MICRONAUT-AM EUCAST assay comparative performance |
| title | Evaluation of Etest and MICRONAUT-AM Assay for Antifungal Susceptibility Testing of <i>Candida auris</i>: Underestimation of Fluconazole Resistance by MICRONAUT-AM and Overestimation of Amphotericin B Resistance by Etest |
| title_full | Evaluation of Etest and MICRONAUT-AM Assay for Antifungal Susceptibility Testing of <i>Candida auris</i>: Underestimation of Fluconazole Resistance by MICRONAUT-AM and Overestimation of Amphotericin B Resistance by Etest |
| title_fullStr | Evaluation of Etest and MICRONAUT-AM Assay for Antifungal Susceptibility Testing of <i>Candida auris</i>: Underestimation of Fluconazole Resistance by MICRONAUT-AM and Overestimation of Amphotericin B Resistance by Etest |
| title_full_unstemmed | Evaluation of Etest and MICRONAUT-AM Assay for Antifungal Susceptibility Testing of <i>Candida auris</i>: Underestimation of Fluconazole Resistance by MICRONAUT-AM and Overestimation of Amphotericin B Resistance by Etest |
| title_short | Evaluation of Etest and MICRONAUT-AM Assay for Antifungal Susceptibility Testing of <i>Candida auris</i>: Underestimation of Fluconazole Resistance by MICRONAUT-AM and Overestimation of Amphotericin B Resistance by Etest |
| title_sort | evaluation of etest and micronaut am assay for antifungal susceptibility testing of i candida auris i underestimation of fluconazole resistance by micronaut am and overestimation of amphotericin b resistance by etest |
| topic | <i>Candida auris</i> antifungal susceptibility testing Etest MICRONAUT-AM EUCAST assay comparative performance |
| url | https://www.mdpi.com/2079-6382/13/9/840 |
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