Comparison of microdilution broth and disk diffusion for antifungal susceptibility testing against Candida spp.<:Comparison of microdilution broth and disk diffusion for antifungal susceptibility testing against Candida spp.<br> Comparação entre microdiluição e disco difusão para o teste de susceptibilidade aos antifúngicos contra Candida spp.

Abstract

The evolution of fungal resistance can be evaluated by testing susceptibility to antifungal agents. The protocols for susceptibility testing most common are Broth Microdilution (BMD), Disk Diffusion (DD) and E-test. The objective of this study was to compare the susceptibility tests conducted by the BMD and DD methods for amphotericin B and fluconazole against Candida spp. isolated in Fortaleza/CE. Were used 40 C. albicans, 50 C. tropicalis and 47 C. parapsilosis isolated from blood and urine samples of patients treated at Fortaleza General Hospital. The tests were conducted by the BMD and DD methods according to protocols M27-A3 and M44-A2 of the CLSI. These methods were compared and the percentages of agreement were calculated. For amphotericin B and fluconazole was a predominance of strains with reduced susceptibility. The percentage of agreement for the methods tested was above 97%. No serious errors were detected. The use of DD for performing antifungal susceptibility testing can be applied in routine laboratory tests, since one technique is easy, inexpensive, and reliable when compared to the BMD without compromising the results for the strains of C. albicans, C. tropicalis and C. parapsilosis.A evolução da resistência fúngica pode ser avaliada pelo teste de susceptibilidade aos antifúngicos. Os protocolos mais utilizados para testes de susceptibilidade são a micro diluição em caldo (MDC), disco difusão (DD) e E-test. O objetivo principal deste estudo foi comparar os testes de sensibilidade realizados pelos métodos de MDC e DD para a anfotericina B e o fluconazol contra cepas de Candida spp. isoladas em Fortaleza/CE. Foram utilizadas 40 C. albicans, 50 C. tropicalis e 47 C. parapsilosis, isoladas de amostras de sangue e urina de pacientes atendidos no Hospital Geral de Fortaleza. Os testes foram realizados pelos métodos MDC e DD, de acordo com os protocolos M27-A3 e M44-A2 do CLSI. As metodologias foram comparadas e calculadas os percentuais de concordância. Para a anfotericina B e fluconazol, ocorreu um predomínio de cepas com susceptibilidade. O percentual de concordância para as metodologias foi acima de 97% e não foram detectados erros graves. A utilização de DD para realização de testes de susceptibilidade antifúngica pode ser aplicada na rotina laboratorial, pois é uma técnica fácil, barata, e de confiança quando comparada ao teste de MDC, sem comprometer os resultados para as cepas de C. albicans, C. tropicalis e C. parapsilosis.

Keywords

• Microdilution broth
• Diffusion Disk
• Candida sp.