In vitro activity of anidulafungin, caspofungin, fluconazole and amphotericin B against biofilms and planktonic forms of Candida species isolated from blood culture in patients with hematological malignancies.
Objective: The aim of the present study was to evaluate the in vitro susceptibility of anidulafungin, caspofungin, fluconazole and conventional amphotericin B against biofilms and planktonic forms of Candida species isolated from blood culture in patients with hematological malignancies.
Methods: Antifungal susceptibility for planktonic forms and biofilms of Candida was determined by broth microdilution method as described by Clinical and Laboratory Standards Institute M27 methodology and metabolic XTT-based [2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] reduction assay, respectively.
Results: A total of 75 Candida isolates were evaluated between 2006-2018 yy at the National Research Center for Hematology, Russia, Moscow. Biofilm production was detected in 34 (45.3%) Candida species. Antifungal susceptibility was tested for 27 common species of Candida forming biofilms (8 C.krusei, 7 C.tropicalis, 7 C.albicans, 5 C.parapsilosis). MICs below the susceptibility breakpoints were found for 100% of planktonic forms of Candida species for anidulafungin, 85.2% for caspofungin, and 66.7% for fluconazole. Amphotericin B MIC90 for Candida species were less than or equal to 1 μg/ml. Candida biofilms were susceptible in vitro for both tested echinocandins, but MIC80 of anidulafungin were lower compared to caspofungin. The highest MIC80 against Candida biofilms was found for fluconazole (>1,024 μg/ml for all tested isolates) and for conventional amphotericin B (range 4-16 μg/ml).
Conclusions: The majority of Candida isolates grown as planktonic forms were susceptible to anidulafungin, caspofungin, conventional amphotericin B and fluconazole. Anidulafungin displayed higher activity against Candida biofilms than caspofungin. All Candida biofilms were resistant to fluconazole and conventional amphotericin B.