Efficacy of liposomal amphotericin B and anidulafungin using an antifungal lock technique (ALT) for catheter-related Candida albicans and Candida glabrata infections in an experimental model

OBJECTIVE: The aims of this study were as follows. First, we sought to compare the in vitro susceptibility of liposomal amphotericin B (LAmB) and anidulafungin on Candida albicans and Candida glabrata biofilms growing on silicone discs. Second, we sought to compare the activity of LAmB versus anidulafungin for the treatment of experimental catheter-related C. albicans and C. glabrata infections with the antifungal lock technique in a rabbit model. METHODS: Two C. albicans and two C. glabrata clinical strains were used. The minimum biofilm eradication concentration for 90% eradication (MBEC(90)) values were determined after 48h of treatment with LAmB and anidulafungin. Confocal microscopy was used to visualize the morphology and viability of yeasts growing in biofilms. Central venous catheters were inserted into New Zealand rabbits, which were inoculated of each strain of C. albicans and C. glabrata. Then, catheters were treated for 48h with saline or with antifungal lock technique using either LAmB (5mg/mL) or anidulafungin (3.33mg/mL). RESULTS: In vitro: anidulafungin showed greater activity than LAmB against C. albicans and C. glabrata strains. For C. albicans: MBEC(90) of anidulafungin versus LAmB: CA176, 0.03 vs. 128 mg/L; CA180, 0.5 vs. 64 mg/L. For C. glabrata: MBEC(90) of anidulafungin versus LAmB: CG171, 0.5 vs. 64 mg/L; CG334, 2 vs. 32 mg/L. In vivo: for C. albicans species, LAmB and anidulafungin achieved significant reductions relative to growth control of log(10) cfu recovered from the catheter tips (CA176: 3.6±0.3 log(10) CFU, p≤0.0001; CA180: 3.8±0.1 log(10) CFU, p≤0.01). For C. glabrata, anidulafungin lock therapy achieved significant reductions relative to the other treatments (CG171: 4.8 log(10) CFU, p≤0.0001; CG334: 5.1 log(10) CFU, p≤0.0001) CONCLUSIONS: For the C. albicans strains, both LAmB and anidulafungin may be promising antifungal lock technique for long-term catheter-related infections; however, anidulafungin showed significantly higher activity than LAmB against the C. glabrata strains.