First itraconazole resistant Aspergillus fumigatus clinical isolate harbouring a G54E substitution in Cyp51Ap in South America / Primer aislamiento clínico en Sudamérica de una cepa de Aspergillus fumigatus resistente a itraconazol con la sustitución G54E en Cyp51Ap

Background. A 27-year-old male rural worker was admitted with a fungal keratitis due to an injury involving plant detritus. Materials and methods. Specimens were collected for microscopy examination and culture. The isolate was identified by morphological and molecular criteria. Susceptibility testing was performed using CLSI methods. CYP51A gene was PCR amplified and sequenced. Results. An Aspergillus fumigatus strain resistant to itraconazole (MIC>8μg/ml) was isolated. The isolate was susceptible to amphotericin B, posaconazole, voriconazole and caspofungin. CYP51A sequencing showed two mutations leading on the G54E substitution. The patient received natamycin as treatment. Conclusions. This is the first report in South America of a clinical A. fumigatus strain carrying the substitution G54E at Cyp51Ap associated with itraconazole resistance. Considering the patient was azole-naive, this resistant isolate may have been acquired from the environment (AU)

Antecedentes. Un trabajador rural de 27años de edad fue hospitalizado con una queratitis fúngica debido a un traumatismo con un resto vegetal. Materiales y métodos. Se tomaron las muestras para los exámenes de microscopía y cultivo. El aislamiento se identificó mediante criterios morfológicos y moleculares. Se realizaron pruebas de sensibilidad a los antifúngicos siguiendo el documento del CLSI. Se amplificó y secuenció el gen CYP51A de la cepa. Resultados. Se aisló una cepa de Aspergillus fumigatus resistente a itraconazol (CIM>8μg/ml). El aislamiento resultó sensible a la anfotericina B, el posaconazol, el voriconazol y la caspofungina. La secuenciación del gen CYP51 reveló 2 mutaciones que generan la sustitución G54E. El paciente fue tratado con natamicina oftálmica. Conclusiones. Este es el primer caso informado en Sudamérica de una cepa clínica de A. fumigatus con la sustitución G54E en el Cyp51Ap, asociada con resistencia al itraconazol. Teniendo en cuenta que el paciente no había recibido nunca antes tratamiento alguno con azoles, podría haber adquirido esta cepa resistente del ambiente (AU)

First itraconazole resistant Aspergillus fumigatus clinical isolate harbouring a G54E substitution in Cyp51Ap in South America.

BACKGROUND: A 27-year-old male rural worker was admitted with a fungal keratitis due to an injury involving plant detritus. MATERIALS AND METHODS: Specimens were collected for microscopy examination and culture. The isolate was identified by morphological and molecular criteria. Susceptibility testing was performed using CLSI methods. CYP51A gene was PCR amplified and sequenced. RESULTS: An Aspergillus fumigatus strain resistant to itraconazole (MIC>8µg/ml) was isolated. The isolate was susceptible to amphotericin B, posaconazole, voriconazole and caspofungin. CYP51A sequencing showed two mutations leading on the G54E substitution. The patient received natamycin as treatment. CONCLUSIONS: This is the first report in South America of a clinical A. fumigatus strain carrying the substitution G54E at Cyp51Ap associated with itraconazole resistance. Considering the patient was azole-naive, this resistant isolate may have been acquired from the environment.

Prevalencia y sensibilidad a los antifúngicos de Candida albicans y sus especies relacionadas, Candida dubliniensis y Candida africana aisladas de muestras vulvovaginales en un hospital de Argentina / Prevalence and antifungal susceptibility of Candida albicans and its related species Candida dubliniensis and Candida africana isolated from vulvovaginal samples in a hospital of Argentina

Candida africana taxonomical status is controversial. It was proposed as a separate species within the Candida albicans species complex; however, phylogenetic analyses suggested that it is an unusual variety of C. albicans. The prevalence of C. albicans-related species (Candida dubliniensis and C. africana) as vulvovaginal pathogens is not known in Argentina. Moreover, data on antifungal susceptibility of isolates causing vulvovaginal candidiasis is scarce. The aims of this study were to establish the prevalence of C. dubliniensis and C. africana in vaginal samples and to evaluate the antifungal susceptibilities of vaginal C. albicans species complex strains. We used a molecular-based method coupled with a new pooled DNA extraction methodology to differentiate C. dubliniensis and C. africana in a collection of 287 strains originally identified as C. albicans isolated from an Argentinian hospital during 2013. Antifungal susceptibilities to fluconazole, clotrimazole, itraconazole, voriconazole, nystatin, amphotericin B and terbinafine were evaluated by using the CLSI M27-A3 and M27-S4 documents. Of the 287 isolates, 4 C. dubliniensis and one C. africana strains (1.39% and 0.35% prevalence, respectively) were identified. This is the first description of C. africana in Argentina and its identification was confirmed by sequencing the ITS2 region and the hwp1 gene. C. dubliniensis and C. africana strains showed very low MIC values for all the tested antifungals. Fluconazole-reduced-susceptibility and azole cross-resistance were observed in 3.55% and 1.41% of the C. albicans isolates, respectively. These results demonstrate that antifungal resistance is still a rare phenomenon in this kind of isolates.

La clasificación taxonómica de Candida africana está en discusión, es considerada una nueva especie dentro del complejo C. albicans o una variedad inusual de C. albicans. La prevalencia de las especies relacionadas a C. albicans (C. dubliniensis y C. africana) como agentes de vulvovaginitis en Argentina se desconoce. Los objetivos de este trabajo fueron determinar la prevalencia de C. dubliniensis y C. africana en muestras vaginales y evaluar la sensibilidad a los antifúngicos de aislamientos vaginales de las especies del complejo C. albicans. Para diferenciar C. dubliniensis y C. africana utilizamos un método molecular asociado a un nuevo método de extracción de ADN. Se utilizó una colección de 287 cepas originalmente identificadas como C. albicans aisladas durante 2013 en un hospital de Argentina. Se evaluó la sensibilidad a fluconazol, clotrimazol, itraconazol, voriconazol, nistatina, anfotericina B y terbinafina utilizando los documentos M27-A3 y M27-S4 del CLSI. De los 287 aislamientos, se identificaron 4 C. dubliniensis y 1 C. africana (1,39 y 0,35% de prevalencia, respectivamente). Esta es la primera descripción de C. africana en Argentina. Su identificación fue confirmada por secuenciación de la región ITS2 y del gen hwp1. Las cepas identificadas como C. dubliniensis y C. africana mostraron valores de CIM muy bajos para todos los antifúngicos probados. En los aislamientos de C. albicans, la sensibilidad reducida al fluconazol y la resistencia cruzada a todos los azoles se observó en el 3,55% y el 1,41%, respectivamente. Estos resultados demuestran que la resistencia a los antifúngicos es todavía un fenómeno raro en este tipo de aislamientos.

Prevalence and antifungal susceptibility of Candida albicans and its related species Candida dubliniensis and Candida africana isolated from vulvovaginal samples in a hospital of Argentina.

Candida africana taxonomical status is controversial. It was proposed as a separate species within the Candida albicans species complex; however, phylogenetic analyses suggested that it is an unusual variety of C. albicans. The prevalence of C. albicans-related species (Candida dubliniensis and C. africana) as vulvovaginal pathogens is not known in Argentina. Moreover, data on antifungal susceptibility of isolates causing vulvovaginal candidiasis is scarce. The aims of this study were to establish the prevalence of C. dubliniensis and C. africana in vaginal samples and to evaluate the antifungal susceptibilities of vaginal C. albicans species complex strains. We used a molecular-based method coupled with a new pooled DNA extraction methodology to differentiate C. dubliniensis and C. africana in a collection of 287 strains originally identified as C. albicans isolated from an Argentinian hospital during 2013. Antifungal susceptibilities to fluconazole, clotrimazole, itraconazole, voriconazole, nystatin, amphotericin B and terbinafine were evaluated by using the CLSI M27-A3 and M27-S4 documents. Of the 287 isolates, 4 C. dubliniensis and one C. africana strains (1.39% and 0.35% prevalence, respectively) were identified. This is the first description of C. africana in Argentina and its identification was confirmed by sequencing the ITS2 region and the hwp1 gene. C. dubliniensis and C. africana strains showed very low MIC values for all the tested antifungals. Fluconazole-reduced-susceptibility and azole cross-resistance were observed in 3.55% and 1.41% of the C. albicans isolates, respectively. These results demonstrate that antifungal resistance is still a rare phenomenon in this kind of isolates.

Epidemiology and antifungal susceptibilities of yeasts causing vulvovaginitis in a teaching hospital.

Vulvovaginal candidiasis is one of the most common mycosis. However, the information about antifungal susceptibilities of the yeasts causing this infection is scant. We studied 121 yeasts isolated from 118 patients with vulvovaginal candidiasis. The isolates were identified by phenotypic and molecular methods, including four phenotypic methods described to differentiate Candida albicans from C. dubliniensis. Antifungal susceptibility testing was performed according to CLSI documents M27A3 and M27S4 using the drugs available as treatment option in the hospital. Diabetes, any antibacterial and amoxicillin treatment were statistically linked with vulvovaginal candidiasis, while oral contraceptives were not considered a risk factor. Previous azole-based over-the-counter antifungal treatment was statistically associated with non-C.albicans yeasts infections. The most common isolated yeast species was C. albicans (85.2 %) followed by C. glabrata (5 %), Saccharomyces cerevisiae (3.3 %), and C. dubliniensis (2.5 %). Fluconazole- and itraconazole-reduced susceptibility was observed in ten and in only one C. albicans strains, respectively. All the C. glabrata isolates showed low fluconazole MICs. Clotrimazole showed excellent potency against all but seven isolates (three C. glabrata, two S. cerevisiae, one C. albicans and one Picchia anomala). Any of the strains showed nystatin reduced susceptibility. On the other hand, terbinafine was the less potent drug. Antifungal resistance is still a rare phenomenon supporting the use of azole antifungals as empirical treatment of vulvovaginal candidiasis.