In Vitro and In Vivo Efficacy of Amphotericin B Combined with Posaconazole against Experimental Disseminated Sporotrichosis

Abstract

bWe evaluated the combination of posaconazole with amphotericin B in vitro and in a murine model of systemic infections caused by Sporothrix brasiliensis and Sporothrix schenckii sensu stricto. In vitro data demonstrated a synergistic effect, and although posaconazole alone was effective against sporotrichosis, efficacy in terms of survival and burden reduction was increased with the combination. This combination might be an option against disseminated sporotrichosis, especially when itraconazole or amphotericin B at optimal doses are contraindicated. Disseminated infection is the most severe manifestation of sporotrichosis, occurring mainly in immunocompromised patients, although it has also been reported in immunocompetent people (1, 2). The Sporothrix schenckii complex encompasses four species able to cause sporotrichosis in humans (3, 4). Treatment of disseminated infections is carried out with amphotericin B and maintenance with itraconazole, showing various outcomes (5-7). Posaconazole has shown low MICs against Sporothrix spp. (8), and although only one study has explored its clinical role, its safety and efficacy in animal models indicate that this compound could be a good alternative for the treatment of disseminated sporotrichosis (5, 9). Seeking to enhance the treatment against sporotrichosis, posaconazole was evaluated in combination with amphotericin B against murine systemic infections by Sporothrix brasiliensis and S. schenckii sensu stricto.Two strains of S. brasiliensis (FMR 8319 and FMR 8326) and two strains of S. schenckii sensu stricto (FMR 8606 and FMR 8609) in the mold phase were included in the study. The MICs of amphotericin B (Sigma-Aldrich Co., St. Louis, MO, USA) and posaconazole (Schering-Plough, Kenilworth, NJ, USA.) were determined from 7-day-old cultures, in accordance with the CLSI guidelines (10), and the activity of the drug combination was tested using the checkerboard method. The fractional inhibitory concentration index (FICI) was calculated, and the combination was defined as synergistic at an FICI of Յ0.5, indifferent at an FICI of Ͼ0.5 and Յ4.0, and antagonistic at an FICI of Ͼ4.0 (11). The tests were carried out in duplicate.For the in vivo study, the inocula were prepared from the filamentous growth by flooding the surface of the cultures with saline solution and scraping the sporulating mycelia. The resulting conidial suspension was transferred to potato dextrose broth and incubated in an orbital shaker at 150 rpm and 30°C for 5 days. The cultures were then filtered through sterile gauze and centrifuged at 325 ϫ g. The conidial suspension was adjusted to the desired concentrations by hemocytometer counting (9). Four-week-old OF-1 male mice (Charles River, Criffa S.A., Barcelona, Spain) with a mean weight of 30 g were infected intravenously (i.v.) via the lateral tail vein with 2 ϫ 10 7 CFU in 0.2 ml of sterile saline. Six groups of 15 animals/group, 10 for survival and 5 for tissue burden studies, were established for each strain. Treatment groups received amphoterici...

Identification of two potential inhibitors of Sporothrix brasiliensis and Sporothrix schenckii in the Pathogen Box collection

“…The in vitro and in vivo activity of posaconazole against Sporothrix spp. is well known [21,24]; however, its high costs compromises usage in lower-income countries of South America, like Brazil, where sporotrichosis also figures as a higly prevalent mycosis.…”

Monitoring Fungal Burden and Viability of Sporothrix spp. in Skin Lesions of Cats for Predicting Antifungal Treatment Response

“…after the onset of antifungal treatment. Previous studies have shown that some therapeutic protocols may reduce the fungal burden in sporotrichosis, even when the infection is caused by S. brasiliensis [ 10 , 11 , 12 , 13 ]. Recently, Souza et al [ 13 ] reported a significant reduction in the fungal burden within 5 to 11 weeks after start of antifungal treatment in cats with sporotrichosis caused by S. brasiliensis .…”

Multicenter, International Study of MIC/MEC Distributions for Definition of Epidemiological Cutoff Values for Sporothrix Species Identified by Molecular Methods

“…Ketoconazole is not used as much given its low efficacy and potentially severe side effects (13,16). Among the newer triazoles, in vivo and in vitro activity has been reported with posaconazole in combination with amphotericin B, while voriconazole has not been considered a therapeutic choice for these infections due to its high MICs (19,20).…”