Fluconazole-resistant Candida parapsilosis: fast detection of the Y132F ERG11p substitution, and a proposed microsatellite genotyping scheme.
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Guinea Jesús, Alcoceba Eva, Padilla Eduardo, Ramírez Aída, De Carolis Elena, Sanguinetti Maurizio, Muñoz-Algarra María, Durán-Valle Teresa, Quiles-Melero Inmaculada, Merino Paloma, González-Romo Fernando, Sánchez-García Aída, Gómez-García-de-la-Pedrosa Elia, Pérez-Ayala Ana, Mantecón-Vallejo María Ángeles, Pemán Javier, Cuétara María Soledad, Zurita Nelly Daniela, García-Esteban Coral, Martínez-Jiménez María Del Carmen, Sánchez Castellano Miguel Ángel, Reigadas Elena, Muñoz Patricia, Escribano Pilar
Аннотация
METHODS: A total of 223 C. parapsilosis isolates (one patient each) from 20 hospitals, located in Spain and Italy were selected. Isolates were fluconazole-resistant (n = 94; harbouring the Y132F ERG11p substitution [n = 85], the G458S substitution [n = 6], the R398I substitution [n = 2], or the wild-type ERG11 gene sequence) or fluconazole-susceptible (n = 129). Two targeted-A395T-mutation PCR formats (conventional and real-time) were engineered and optimized on fluconazole-susceptible and fluconazole-resistant pure-cultured isolates, thus skipping DNA extraction. Two genotyping schemes were compared: Scheme 1 (CP1, CP4a, CP6, and B markers), and Scheme 2 (6A, 6B, 6C, CP1, CP4a, and CP6 markers).
RESULTS: The screening performed using both PCR formats showed 100% specificity (fluconazole-susceptible isolates; n = 129/129) and sensitivity (Y132F isolates; n = 85/85) values; however, results were available in 3 and 1.5 hours with the conventional and real-time PCR formats, respectively. Overall, Scheme 1 showed higher genetic diversity than Scheme 2, as shown by the number of alleles detected (n = 98; mean 23, range 13-38), the significantly higher observed and expected heterozygosity, and the probability of identity index (2.5 × 10-6). Scheme 2 markers did not provide further genotypic discrimination of Y132F fluconazole-resistant genotypes.
CONCLUSION: Both proposed PCR formats allow us to speed up the accurate detection of substitution Y132F ERG11p in C. parapsilosis isolates with 100% specificity and sensitivity. In addition, we recommend CP1, CP4a, CP6, and B microsatellite markers for genotyping fluconazole-resistant isolates.