Direct Antifungal Susceptibility Testing of Candida Species from Blood Culture Bottles
Project no. 29671 · Status: Kapanmış (Yayın bekleniyor) · 2023
Summary
<p>Objective: Candidemia has a high mortality rate, and early initiation of effective treatment is crucial. Given the rising antifungal resistance rates, rapid antifungal susceptibility testing is essential. This study aimed to assess the feasibility of rapid antifungal susceptibility testing using the disk diffusion method directly from growth-positive blood culture bottles, compared to standard methods.</p><p><br></p><p>Materials and Methods: Blood culture specimens sent to Ege University Medical Faculty Hospital between December 2023 and December 2024, in which only yeast cells were detected on Gram stain, were included in the study. To expand the sample size, previously isolated Candida species, ATCC reference strains, and echinocandin- and fluconazole-resistant</p><p>C. parapsilosis strains were inoculated into blood culture bottles for standardization.</p><p><br></p><p>For direct susceptibility testing, yeast suspensions were prepared from growth-positive blood culture bottles, and antifungal susceptibility tests were performed using disk diffusion (KDD) and standard broth microdilution (SMD) tests following CLSI M27-A3 guidelines and disk diffusion (DD) tests according to CLSI M44-A2 guidelines from culture were conducted for comparison. The data obtained were evaluated by concordance analysis and correlation and regression analysis.</p><p><br></p><p>Results: A total of 104 Candida strains were included in the study: 30 C. albicans, 30</p><p>C. parapsilosis, 30 N. glabrata (C. glabrata), 10 C. tropicalis, two C. fabianii, one C. lusitaniae, and one C. marxinanus (C. kefyr). When SMD was compared with KDD, categorical agreement for fluconazole was 100% for C. albicans, N. glabratus and C. tropicalis isolates and 90% for C. parapicillosis. Categorical agreement for mycafungin was 96.7% for C. albicans, 86.7% for C. parapicillosis, 53.3% for N. glabratus and 90% for C. tropicalis.</p><p><br></p><p>Conclusion: The findings suggest that KDD may be a reliable alternative to fluconazole, but mycafungin susceptibility tests may vary depending on the species. Especially in species with low compliance such as N. glabratus, the results should be confirmed by standard methods. It is concluded that this method should be evaluated in larger studies for different antifungals and species.</p>