Antifungal Susceptibility In Vitro Determined by the Etest(r) for Candida Obtained from the Oral Cavity of Irradiated and Elderly Individuals

ABSTRACT

This study aimed to evaluate the in vitro antifungal susceptibility of Candida species of head-and-neck-irradiated patients (Group 1), non-institutionalized (Group 2) and institutionalized elders (Group 3) using Etest(r) methodology. Candida was isolated from saliva and presumptively identified by CHROMagar Candida(r), confirmed by morphological criteria, carbohydrate assimilation (API 20C AUX(r)) and genetic typing (OPE 18). The collection was made from 29, 34 and 29 individuals (Groups 1, 2 and 3, respectively) with 67 isolates. Etest(r) strips (ketoconazole, itraconazole, fluconazole, amphotericin B and flucytosine) on RPMI (Roswell Park Memorial Institute) agar, on duplicate, were used to evaluate susceptibility. ATTC (American Type Culture Collection) 10231 (Candida albicans) was used as quality control. Among the 67 isolates of Candida species, most were susceptible to azoles, flucytosine and amphotericin B. None of the isolates showed resistance and dose-dependent susceptibility to amphotericin B. There were nine strains resistant to itraconazole, six to fluconazole and two to ketoconazole and ten dose-dependent, mainly to flucytocine. The highest MIC (minimum inhibitory concentration) to C. albicans, C. tropicalis, C. parapsilosis was 2.671 μg.mL-1, 8.104 μg.mL-1, 4.429 μg.mL-1, all for flucytosine. C. krusei and C. glabrata were associated with higher MIC for azoles and C. glabrata with higher MIC to flucytosine. In summary, susceptibility to all tested antifungal agents was evident. The isolates were more resistant to itraconazole and dose-dependent to flucytosine. A comparison of C. albicans in the three groups showed no outliers. Higher MIC was associated with C. krusei and C. glabrata.

RESUMO

Esse estudo objetivou avaliar a susceptibilidade antifúngica in vitro de espécies de Candida obtidas de pacientes irradiados em cabeça e pescoço (Grupo 1), idosos não institucionalizados (Grupo 2) e idosos institucionalizados (Grupo 3) usando a metodologia Etest(r). Candida foi isolada da saliva e identificada presuntivamente pelo teste CHROMagar Candida(r), confirmada pelo critério morfológico, assimilação de carboidratos API 20C AUX(r) e identificação genética (OPE 18). A coleta foi feita em 29, 34 e 29 indivíduos (Grupos 1, 2 and 3, respectivamente) com 67 isolados. As fitas de Etest(r) (cetoconazol, itraconazol, fluconazol, anfotericina B and flucitosina) em meio ágar RPMI (Roswell Park Memorial Institute), em duplicata, foram utilizados para avaliar a susceptibilidade. A ATTC (American Type Culture Collection) 10231 (Candida albicans) foi usada como controle de qualidade. Dos 67 isolados de espécies de Candida, a maioria foi susceptíveis aos azoles, flucitosina e anfotericina B. Nenhum dos isolados mostrou resistência ou susceptibilidade dose-dependente a anfotericina B. Houve nove espécies resistentes ao itraconazol, seis ao fluconazol e duas ao cetoconazol e dez dose-dependentes, principalmente a flucitosina. Os maiores valores de MIC (mínima concentração inibitória) para C. albicans, C. tropicalis, C. parapsilosis foram, respectivamente, 2,671 μg.mL-1, 8,104 μg.mL-1, 4, 429 μg.mL-1, todos para a flucitosina. C. krusei e C. glabrata foram associadas a um maior MIC para azoles e C. glabrata com maior MIC para flucitosina. Em resumo, a susceptibilidade a todos os antifúngicos testados foi evidente. Os isolados foram mais resistentes ao itraconazol e dose dependentes para a flucitosina. A comparação para C. albicans nos três grupos não mostrou diferença. Os maiores valores de MIC estavam relacionados a C. krusei e C. glabrata.