Surveillance of azole resistance among Candida non-albicans clinical isolates from patients with invasive fungal infections

Abstract number: 1734_176

Kazakos E., Moschous E., Tsiakiri E., Alexiou-Daniel S.

Objectives: The aim of the present study was to document the in vitro susceptibilities of Candida spp. representing predominantly invasive forms of candidiasis, to currently available triazole agents and ketoconazole in order to assess the rates of resistance per species and identify possible implications for antifungal therapy selection.

Materials and Methods: A total of 68 isolates (4 C. ciferrii

, 6 C. dubliniensis, 3 C. famata, 10 C. glabrata, 1 C. haemulonii, 3 C. krusei, 5 C. kefyr, 4 C. lusitaniae, 24 C. parapsilosis, 2 C. sphaerica, 6 C. tropicalis) were included. The strains originated from blood, respiratory tract specimens, surgical wounds and normally sterile sites and each of them represented a unique infectious episode. Identification to species level was achieved by the VITEK 2 automated system with greater then 98% probability. Antifungal susceptibility testing to itraconazole, voriconazole, posaconazole, fluconazole and ketoconazole was performed using the Etest assay according to the manufacturers' instructions. MIC data were interpreted by applying the CLSI breakpoints (document M27-A2) and tentative MICs' previously published.

Results: Overall, the rates of resistance recorded among all isolates were 26.4% for itraconazole, 19.6% for posaconazole, 13.2% for voriconazole, 16.1% for fluconazole and 10.1% for ketoconazole. All fluconazole-resistant strains exhibited resistance to posaconazole (MIC≥8ug/mL) whereas 72.2% of those strains appeared to be less susceptible to voriconazole (MIC≥2ug/mL). Extended rates of cross-resistance were also documented between fluconazole and itraconazole (100% of fluconazole resistant isolates). Pan-azole resistance was evident in 1 C. famata, 5 C. glabrata and 1 C. parapsilosis isolates.

Conclusions: Although our study is limited by the small number of invasive Candida isolates from a single institution, our data provides further evidence regarding the patterns of triazole cross-resistance, previously reported. The degree of resistance recorded highlights the need for introduction of antifungal susceptibility testing in routine practice and raises important clinical issues related to therapeutic options in patients with invasive candidiasis.