Early phenotypic detection of fluconazole- and anidulafungin-resistant Candida glabrata isolates.
Journal
The Journal of antimicrobial chemotherapy
ISSN: 1460-2091
Titre abrégé: J Antimicrob Chemother
Pays: England
ID NLM: 7513617
Informations de publication
Date de publication:
29 05 2022
29 05 2022
Historique:
received:
17
11
2021
accepted:
15
02
2022
pubmed:
25
3
2022
medline:
3
6
2022
entrez:
24
3
2022
Statut:
ppublish
Résumé
Increased fluconazole and echinocandin resistance in Candida glabrata requires prompt detection in routine settings. A phenotypic test based on the EUCAST E.DEF 7.3.2 protocol was developed for the detection of fluconazole- and anidulafungin-resistant isolates utilizing the colorimetric dye XTT. Thirty-one clinical C. glabrata isolates, 11 anidulafungin resistant and 14 fluconazole resistant, were tested. After optimization studies, 0.5-2.5 × 105 cfu/mL of each isolate in RPMI 1640 + 2% d-glucose medium containing 100 mg/L XTT + 0.78 μΜ menadione and 0.06 mg/L anidulafungin (S breakpoint) or 16 mg/L fluconazole (I breakpoint) in 96-well flat-bottom microtitration plates were incubated at 37°C for 18 h; we also included drug-free wells. XTT absorbance was measured at 450 nm every 15 min. Differences between the drug-free and the drug-treated wells were assessed using Student's t-test at different timepoints. ROC curves were used in order to identify the best timepoint and cut-off. The XTT absorbance differences between fluconazole-containing and drug-free wells were significantly lower for the resistant isolates compared with susceptible increased exposure isolates (0.08 ± 0.05 versus 0.25 ± 0.06, respectively, P = 0.005) at 7.5 h, with a difference of <0.157 corresponding to 100% sensitivity and 94% specificity for detection of resistance. The XTT absorbance differences between anidulafungin-containing and drug-free wells were significantly lower for the resistant isolates compared with susceptible isolates (0.08 ± 0.07 versus 0.200 ± 0.03, respectively, P < 0.001) at 5 h, with a difference of <0.145 corresponding to 91% sensitivity and 100% specificity, irrespective of underlying mutations. A simple, cheap and fast phenotypic test was developed for detection of fluconazole- and anidulafungin-resistant C. glabrata isolates.
Sections du résumé
BACKGROUND
Increased fluconazole and echinocandin resistance in Candida glabrata requires prompt detection in routine settings. A phenotypic test based on the EUCAST E.DEF 7.3.2 protocol was developed for the detection of fluconazole- and anidulafungin-resistant isolates utilizing the colorimetric dye XTT.
METHODS
Thirty-one clinical C. glabrata isolates, 11 anidulafungin resistant and 14 fluconazole resistant, were tested. After optimization studies, 0.5-2.5 × 105 cfu/mL of each isolate in RPMI 1640 + 2% d-glucose medium containing 100 mg/L XTT + 0.78 μΜ menadione and 0.06 mg/L anidulafungin (S breakpoint) or 16 mg/L fluconazole (I breakpoint) in 96-well flat-bottom microtitration plates were incubated at 37°C for 18 h; we also included drug-free wells. XTT absorbance was measured at 450 nm every 15 min. Differences between the drug-free and the drug-treated wells were assessed using Student's t-test at different timepoints. ROC curves were used in order to identify the best timepoint and cut-off.
RESULTS
The XTT absorbance differences between fluconazole-containing and drug-free wells were significantly lower for the resistant isolates compared with susceptible increased exposure isolates (0.08 ± 0.05 versus 0.25 ± 0.06, respectively, P = 0.005) at 7.5 h, with a difference of <0.157 corresponding to 100% sensitivity and 94% specificity for detection of resistance. The XTT absorbance differences between anidulafungin-containing and drug-free wells were significantly lower for the resistant isolates compared with susceptible isolates (0.08 ± 0.07 versus 0.200 ± 0.03, respectively, P < 0.001) at 5 h, with a difference of <0.145 corresponding to 91% sensitivity and 100% specificity, irrespective of underlying mutations.
CONCLUSIONS
A simple, cheap and fast phenotypic test was developed for detection of fluconazole- and anidulafungin-resistant C. glabrata isolates.
Identifiants
pubmed: 35323941
pii: 6551886
doi: 10.1093/jac/dkac075
pmc: PMC9840476
doi:
Substances chimiques
Antifungal Agents
0
Echinocandins
0
Fluconazole
8VZV102JFY
Anidulafungin
9HLM53094I
Types de publication
Journal Article
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
1655-1661Informations de copyright
© The Author(s) 2022. Published by Oxford University Press on behalf of British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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