Comparison of Broth Macrodilution and Microdilution in Testing of Minimal Inhibitory Concentration of Candida Species / 대한임상병리학회지

ABSTRACT

BACKGROUND: Candida species are one ol the major pathogens causing opportunistic infection. The need for a standardized. and clinically relevant method for antifungal susceptibility testing has become more increased because resistance to antifungal agents is now being reported with increasing frequency. The purposes of this study were to measure the minimal inhibitory concentrations actions amphotericin B, flucytosine and fluconazole of clinical isolates of Candida species, and to evaluate broth microdilution method as a more efficient test method, compared with NCCLS standard broth macrodilution. METHODS: The minlmal Inhibitory concentrations of C. parapsilosis ATCC 90018, C, albicans ATCC 90028 and 32 Candida isolates from Korea University Hospital were evaluated against amphotericin B, flucytosine and fluconazole by broth macrodilution and microdilution methods. RESULTS: The minimal inhibitory concentrations of Candida species ranged 0.25 to 1.0 microgram/mL for amphotericin B, 0.125 to 2.0 microgram/mL for flucytosine and 0.125 to 64 microgram/mL for fluconazole. The percent of agreement between NCCLS standard broth macrodilution and microdilution was highest when inoculum size was 0.5-2.5x103 CFU/mL and incubation time was 48 hours, and one fold dilution agreement was 100% for amphotericin B, 100% for flucytosine and 88-96% for fluconazole. CONCLUSIONS: This study showed good agreement of results of broth microdilution test with those of macrodilution, and suggested that broth microdilution method is an accessible and useful method and can be substituted for broth macrodilutlon method with the expectation of good results.