Evaluation of the efficacy of rezafungin, a novel echinocandin, in the treatment of disseminated Candida auris infection using an immunocompromised mouse model.

Background: Multiple cases of Candida auris infection have been reported with high mortality rates owing to its MDR nature. Rezafungin (previously CD101) is a novel echinocandin with enhanced stability and pharmacokinetics that achieves high plasma drug exposure and allows for once weekly dose administration. Objectives: Evaluate the efficacy of rezafungin in the treatment of disseminated C. auris infection using a mouse model of disseminated candidiasis. Methods: Mice were immunosuppressed 3 days prior to infection and 1 day post-infection. On the day of infection, mice were inoculated with 3 × 107C. auris blastospores via the tail vein. Mice were randomized into four groups (n = 20): rezafungin at 20 mg/kg, amphotericin B at 0.3 mg/kg, micafungin at 5 mg/kg and a vehicle control. Treatments were administered 2 h post-infection. Rezafungin was given additionally on days 3 and 6 for a total of three doses, while the remaining groups were treated every day for a total of seven doses. Five mice from each group were sacrificed on days 1, 4, 7 and 10 of the study. Kidneys were removed from each mouse to determine the number of cfu for each respective day. Results: Rezafungin had significantly lower average log10 cfu/g of tissue compared with amphotericin B- and vehicle-treated mice on all days when kidneys were harvested. Additionally, rezafungin-treated mice had significantly lower average log10 cfu/g of tissue compared with micafungin-treated mice on day 10. Conclusions: Our findings show that rezafungin possesses potent antifungal activity against C. auris in a disseminated model of candidiasis.

Efficacy of caspofungin combined with amphotericin B against azole-resistant Candida albicans.

The activity of caspofungin (CFG) combined with amphotericin B (AMB) against azole-resistant Candida albicans was evaluated in vitro (chequerboard) and in vivo (murine). CFG+AMB resulted in positive interactive effects in vitro (fractional inhibitory concentration index 0.75). Compared with untreated controls, CFG+AMB prolonged mouse survival (P = 0.006) and compared with AMB alone, CFG+AMB prolonged mouse survival (P = 0.36); however, the latter difference was not significant. CFG+AMB treatment significantly reduced kidney cfu compared with untreated controls and CFG-treated groups (P < or = 0.05 for both comparisons). In addition, this combination reduced brain cfu significantly compared with untreated controls and AMB-treated mice (P = 0.005 and 0.05, respectively).

Rabbit model of Candida albicans biofilm infection: liposomal amphotericin B antifungal lock therapy.

Catheter-related infections due to Candida albicans biofilms are a leading cause of fungal nosocomial bloodstream infection. In this paper, we describe the development of a model of catheter-associated infection with C. albicans biofilms and show that antifungal lock therapy with liposomal amphotericin B is an effective treatment strategy for these infections. Silicone catheters surgically placed in New Zealand White rabbits were infected with C. albicans, and the rabbits were randomized into three groups: (i) untreated controls, (ii) liposomal amphotericin B lock, and (iii) fluconazole lock. Upon completion of therapy, blood cultures were obtained and the catheters were removed for quantitative culture and scanning electron microscopic analyses. Quantitative cultures revealed that catheters treated with liposomal amphotericin B yielded 0 CFU, which was significant compared to the untreated controls (P < 0.001) and the fluconazole-treated group (P = 0.0079). Although fluconazole treatment tended to have lower CFU compared to untreated controls, there was no difference in mean colony counts between these two groups (1.128 +/- 0.764 and 1.841 +/- 1.141 log(10) CFU/catheter segment, respectively; P = 0.297). Scanning electron microscopy revealed abundant biofilm in the control and fluconazole groups, while the liposomal amphotericin B group was virtually cleared. These findings suggest a possible treatment strategy for the successful salvage of catheters infected with C. albicans biofilms and describe an animal model that may play an important role in the further study of C. albicans biofilm pathogenesis and evaluation of potential antibiofilm agents.