Akademik Veri Yönetim Sistemi
ESCMID Global 2025, Vienna, Avusturya, 11 - 15 Nisan 2025, ss.3286-3287, (Özet Bildiri)
Background Antifungal resistance and treatment failure often result from ineffective targeting, insufficient penetration, increased efflux, or mutations. Heter oresistance, a recently recognised concept, involves subpopulations within susceptible isolates exhibiting varied phenotypic responses to treat ment. Candida auris, listed by the World Health Organization as a priority fungal pathogen, is notably resistant to antifungals. This study aimed to identify heteroresistant subpopulations in Candida auris and other Candida species using Population Profile Analysis (PAP). Methods This study included 14 strains isolated from diverse clinical samples: 6 Candida auris, 4 Candida parapsilosis, 2 Candida dublininensis, and 2 Candida tropicalis. The primary objective was to assess the drug-resistant and susceptible phenotypes in the presence of fluconazole and isolate heteroresistant colonies. Strains were screened on YPD agar plates containing fluconazole at concentrations of 0.5, 1, 2, 4, 8, 16, 32, 64, and 128 μg/mL. A 5 μL of yeast suspensions, prepared via serial dilutions (105, 104, 103, 102 cfu/mL), was added on each fluconazole-containing medium. Colonies growing above the MIC were isolated, and the MIC values of these colonies were determined. PAP graphs were generated for each isolate (Figure 1). Results Using the PAP analysis, subpopulations exhibiting MIC values eight times higher than the MIC of the main isolate were classified as heteroresis tant, as described by El-Halfawy et al. While the MIC of 4 Candida auris isolates was determined to be 8 µg/mL, heteroresistant colonies from these isolates exhibited MIC values of 64 µg/mL. No evidence of heteroresistance was observed in strains of Candida parapsilosis, Candida dublininensis, or Candida tropicalis (Table 1). In the analysis of the C. auris reference strain from the CDC, resistance was confirmed both by microdilution and PAP testing. The results for all isolates are presented in the PAP graph (Figure 2). Conclusions This is the first study on heteroresistance in Candida isolates from our country, highlighting its originality. International studies in this field remain limited. The use of PAP analysis, a novel method locally, underscores this study’s pioneering role in antifungal research