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Susceptibility testing of Prototheca bovis isolates from cases of bovine mastitis using the CLSI reference broth microdilution method and the Sensititre YeastOne colorimetric panel

Investigation article published in Medical Mycology

October 13rd, 2021

A total of 62 Prototheca bovis isolates from cases of bovine mastitis were tested for susceptibility to different antifungal compounds by the Clinical and Laboratory Standards Institute (CLSI) reference microdilution method and a commercial colorimetric microdilution panel (Sensititre YeastOne). All isolates displayed low susceptibility to echinocandins (MICs > 8 μg/ml for anidulafungin, caspofungin, and micafungin), flucytosine (MIC > 64 μg/ml), and the azoles enilconazole and fluconazole (MICs > 4 and > 64 μg/ml, respectively). Moreover, 45.2%, 32.3%, and 1.6% of isolates had MICs > 4 μg/ml for ketoconazole, terbinafine, and voriconazole, respectively, when tested by the CLSI method. In contrast, all isolates were more susceptible to the polyene compounds amphotericin B and nystatin, and itraconazole, posaconazole, and ravuconazole (MICs ≤ 2 μg/ml, in all cases). Comparison of the results obtained in the CLSI and Sensititre methods showed excellent essential agreement (EA) for azoles (98.4% for itraconazole and posaconazole, and 100% for voriconazole) and moderate EA for amphotericin B (72.6%), when MICs were read after 24 h and 48 h of incubation, respectively. In contrast, much lower EA values were obtained in some cases when the MICs for both techniques were determined after 48 h of incubation (e.g., 9.7% for amphotericin B and 69.4% for posaconazole). Therefore, the CLSI broth microdilution method and the Sensititre YeastOne panel can be used indistinctly for susceptibility testing of P. bovis isolates against azoles but not against amphotericin B until further optimization of the test conditions.
Lay summary: The antifungal susceptibility of Prototheca bovis isolates was analyzed. All tested isolates displayed low susceptibility to echinocandins, flucytosine, and some azoles. Excellent agreement of the results of two different test methods was obtained for azoles, but not for the polyene amphotericin B.
Keywords: Prototheca bovis; antifungals; broth microdilution; susceptibility testing




Alvarez-Perez S., Anega B., Diaz A., Gonzalez-Martin JV., Riesgo-Martínez M., Garcia ME. and Blanco JL.




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Susceptibility testing of Prototheca bovis isolates from cases of bovine mastitis using the CLSI reference broth microdilution method and the Sensititre YeastOne colorimetric panel

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Susceptibility testing of Prototheca bovis isolates from cases of bovine mastitis using the CLSI reference broth microdilution method and the Sensititre YeastOne colorimetric panel



Participants:

Universidad ComplutenseDepartamento de Sanidad Animal. Facultad de Veterinaria. Universidad Complutense (UCM).

Comunidad de MadridLaboratorio Regional de Sanidad Animal. Consejería de Medio Ambiente y Ordenación del Territorio. Comunidad de Madrid.

Universidad ComplutenseDepartamento de Medicina y Cirugía Animal. Facultad de Veterinaria. Universidad Complutense (UCM).

Universidad ComplutenseCentro de Vigilancia Sanitaria Veterinaria (VISAVET). Universidad Complutense (UCM).







Medical Mycology
FACTOR YEAR Q
4.076 2020

PMID: 34643716

ISSN: 1369-3786



TITLE: Susceptibility testing of Prototheca bovis isolates from cases of bovine mastitis using the CLSI reference broth microdilution method and the Sensititre YeastOne colorimetric panel


JOURNAL: Med Mycol


NUMERACIÓN: myab063


AÑO: 2021


PUBLISHER: Taylor & Francis


AUTHORS: Alvarez-Perez S., Anega B., Diaz A., Gonzalez-Martin JV., Riesgo-Martínez M., Garcia ME. and Blanco JL.


DOI: https://doi.org/10.1093/mmy/myab063


CITE THIS PUBLICATION:

Alvarez-Perez S., Anega B., Diaz A., Gonzalez-Martin JV., Riesgo-Martínez M., Garcia ME. and Blanco JL. Susceptibility testing of Prototheca bovis isolates from cases of bovine mastitis using the CLSI reference broth microdilution method and the Sensititre YeastOne colorimetric panel. Medical Mycology. myab063. 2021. (A). ISSN: 1369-3786. DOI: 10.1093/mmy/myab063