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Daniel Choi, Harry W Flynn, Darlene Miller, Benjamin David Wilson; Combination Therapy for Candida Endophthalmitis: An in vitro study. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1878.
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© ARVO (1962-2015); The Authors (2016-present)
Antifungal treatment options for Candida endophthalmitis are evolving. Combination therapy is increasingly being used to manage cases. The value of monotherapy versus combination therapy with azoles and amphotericin B remains unclear. We conducted a pilot experiment to evaluate the in vitro efficacy of amphotericin B, voriconazole, and posconazole alone and in combination (amphotericin B plus voriconazole) against Candida isolates from patients with endophthalmitis.
A comparative, experimental microbiological study of antifungal agents against Candida was performed. Isolates included Candida parapsilosis (N=2) and Candida albicans (N=9) collected from 7 vitreous samples and 4 anterior chamber samples recovered in the last 10 years. E tests were used to document the antifungal MICs of the Candida isolates and 2 controls Candida parapsilosis ATCC 22019 and Candida krusei ATCC 6758. Inoculum preparations to achieve a turbidity equivalent of 0.5 McFarland standard were made for each sample and control. The inoculum was spread onto agar plates and allowed to soak for 15 minutes. E test strips (2 amphotericin B, 2 voriconazole, and 1 posconazole) were placed on each agar plate. After one hour, one of the initial amphotericin B and voriconazole E tests were switched for voriconazole and amphotericin B respectively. E test MICs were interpreted after 48 hours described in the E test interpretation protocol. Quality control strains achieved appropriate MIC levels.
All isolates were tested for MIC90 levels at comparable time points. MIC90s were: amphotericin B-0.38 ug/ml ( range 0.047 ug/ml to 0.5 ug/ml), voriconazole 0.008 ug/ml ( 0.003-0.032 ug/ml), posconazole-0.047 ug/ml (0.023-0.125). The MIC90 for amphotericin B plus voriconazole was the same as for voriconazole alone- 0.008 ug/ml (range 0.003-0.032) (ie no additive effect).
This pilot in vitro study demonstrated that voriconazole had the lowest in vitro MICs for these select Candida isolates from patients with endophthalmitis. Additionally, the combination of amphotericin B and voriconazole has no additive effect or increased efficacy against Candida species using the current E test technology.
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