Reduction In Tissue Burden Research Articles

In Vivo Synergy of Amphotericin B plus Posaconazole in Murine Aspergillosis.

Aspergillus fumigatus is the main mold causing invasive fungal infection that shows high mortality rates. Therapeutic failure and the increase in drug resistance make it necessary to explore alternative treatments for this infection. We have evaluated the efficacy of amphotericin B at 0.8 mg/kg or 0.3 mg/kg of body weight combined with 40 mg/kg of posaconazole against three A. fumigatus isolates in a murine model of disseminated infection. The combination of the polyene and the azole led to a greater increase in survival and a significantly greater reduction in tissue burden than monotherapies.

Efficacy of Posaconazole in a Murine Model of Systemic Infection by Saprochaete capitata.

The fungus Saprochaete capitata causes opportunistic human infections, mainly in immunocompromised patients with hematological malignancies. The best therapy for this severe infection is still unknown. We evaluated the in vitro killing activity and the in vivo efficacy of posaconazole at 5, 10, or 20 mg/kg twice a day (BID) in a murine neutropenic model of systemic infection with S. capitata by testing a set of six clinical isolates. Posaconazole showed fungistatic activity against all of the isolates tested. The different doses of the drug, especially the highest one, showed good efficacy, measured by prolonged survival, reduction of (1-3)-β-D-glucan levels in serum, tissue burden reduction, and histopathology.

Efficacy and toxicity evaluation of new amphotericin B micelle systems for brain fungal infections

The aim of this work is to study the micelle systems of amphotericin B (AmB) and surfactant sodium deoxycholate (NaDC) as possible formulations to treat brain fungal infections. Fungizone® and Ambisome® were used as AmB references. The particle size, aggregation state, toxicity and efficacy of AmB:NaDC micelles were studied with increasing proportions of NaDC. Differences in the size and aggregation state of the reference formulations and micellar NaDC formulations might explain the differences in their distribution and therefore in their toxicity and efficacy. AmB:NaDC 1:0.8 and 1:1.5 nano-sized micelle systems showed a poly-aggregated form of AmB and small mean particle size (450–750nm). The AmB:NaDC 1:0.8 and AmB:NaDC 1:1.5 micelle systems studied showed an 8-fold lower toxicity than Fungizone®. Efficacy was examined in a murine candidiasis model by determining the survival rate and tissue burden reduction in kidneys and brain. The AmB:NaDC 1:1.5 micellar system at 5mg/kg of AmB and the highest amount of NaDC (7.5mg/kg) presented a good survival rate, and induced a major clearance of brain infection. The new AmB:NaDC 1:1.5 nano-sized micelle system is a promising formulation with a good efficacy/toxicity ratio, which can be attributed to its particle size, AmB aggregation state and NaDC content.

Evaluation of the Efficacies of Amphotericin B, Posaconazole, Voriconazole, and Anidulafungin in a Murine Disseminated Infection by the Emerging Opportunistic Fungus Sarocladium (Acremonium) kiliense

We evaluated and compared the efficacies of different antifungal drugs against Sarocladium kiliense (formerly Acremonium kiliense), a clinically relevant opportunistic fungus, in a murine model of systemic infection. Three clinical strains of this fungus were tested, and the therapy administered was as follows: posaconazole at 20 mg/kg of body weight (twice daily), voriconazole at 40 mg/kg, anidulafungin at 10 mg/kg, or amphotericin B at 0.8 mg/kg. The efficacy was evaluated by prolonged animal survival, tissue burden reduction, and (1→3)-β-d-glucan serum levels. In general, the four antifungal drugs showed high MICs and poor in vitro activity. The efficacy of the different treatments was only modest, since survival rates were never higher than 40% and no drug was able to reduce fungal load in all the organs for the three strains tested. Posaconazole, in spite of its high MICs (≥16 μg/ml), showed the highest efficacy. The (1→3)-β-d-glucan serum levels were equally reduced by all drugs evaluated.

Efficacy of Posaconazole in Murine Experimental Sporotrichosis

We developed a murine model of systemic sporotrichosis by using three strains of each of the two commonest species causing sporotrichosis, i.e., Sporothrix schenckii sensu stricto and Sporothrix brasiliensis, in order to evaluate the efficacy of posaconazole (PSC). The drug was administered at a dose of 2.5 or 5 mg/kg of body weight twice a day by gavage, and one group was treated with amphotericin B (AMB) as a control treatment. Posaconazole, especially at 5 mg/kg, showed good efficacy against all the strains tested, regardless of their MICs, as measured by prolonged survival, tissue burden reduction, and histopathology.

In Vitro Activity and In Vivo Efficacy of Posaconazole in Treatment of Murine Infections by Different Isolates of the Aspergillus terreus Complex

Posaconazole (PSC) is an antifungal drug recommended as an alternative for the treatment of invasive aspergillosis in patients who are refractory or intolerant to primary antifungal therapy. We have evaluated the in vitro activity of PSC against 21 strains of the Aspergillus terreus complex using both broth microdilution and disk diffusion (Neo Sensitabs) methods. PSC showed the same high level of activity against all the strains with the two in vitro methods used. We developed a murine model of disseminated infection to evaluate the efficacy of PSC at 5, 10, or 20 mg/kg of body weight twice a day by using 6 different strains chosen randomly. PSC showed good efficacy, especially at 20 mg/kg, as measured by prolonged survival, tissue burden reduction, histopathology, and lowered galactomannan levels. The PSC levels in serum on the fourth day of treatment were higher than the MICs for the strains tested.

Efficacy of voriconazole in a murine model of cryptococcal central nervous system infection

We studied the efficacy of voriconazole compared with amphotericin B in a murine model of central nervous system infection by Cryptococcus neoformans. Infection was established intracerebrally. Mice were treated with voriconazole at 10, 40 or 60 mg/kg/day orally or with amphotericin B at 1.5 mg/kg/day intraperitoneally. Treatment began 1 day after infection and continued for 10 days post-infection. Tissue burden studies were performed on day 7 and 1 day after the treatment finished. Both drugs were able to significantly prolong survival with respect to the control group. The highest tissue burden reduction was achieved with voriconazole at 60 mg/kg/day. We have developed a murine model of cryptococcal central nervous system infection and demonstrated that voriconazole has a potential for the treatment of cryptococcosis.

Combined antifungal therapy in a murine infection by Candida glabrata

To develop proper treatments for patients who do not respond to current antifungal treatments, we tested new combinations of antifungal drugs for treating disseminated infections by Candida glabrata in a murine model. Mice were rendered neutropenic by intraperitoneal cyclophosphamide and intravenous 5-fluorouracil administration. The animals were infected intravenously with 2 x 10(8) cfu of C. glabrata. The efficacies of micafungin combined with amphotericin B, fluconazole or flucytosine, and of amphotericin B combined with fluconazole were evaluated by survival and tissue burden reduction. Micafungin plus amphotericin B was the most effective combination at reducing tissue burden. Micafungin at 10 mg/kg combined with amphotericin B at 0.75, 1.5 or 3 mg/kg prolonged survival with respect to the monotherapies, but only the second combination showed a synergistic effect in reducing fungal load in spleen and kidney. Amphotericin B at 1.5 mg/kg combined with micafungin at 5, 10 or 20 mg/kg reduced tissue burden with respect to the monotherapies, but the effects of the three combinations were very similar. These results suggest that amphotericin B in combination with micafungin is promising for the treatment of disseminated C. glabrata infections.

A novel murine model of cerebral scedosporiosis: lack of efficacy of amphotericin B

Cerebral scedosporiosis is a life-threatening infection that is difficult to treat. The aim of this work was to develop a murine model of cerebral infection by Scedosporium apiospermum using intracranial inoculation and to use this model to evaluate the efficacy of amphotericin B deoxycholate and liposomal amphotericin B. Mice were rendered neutropenic by intraperitoneal cyclophosphamide and intravenous (iv) 5-fluorouracil administration. Animals were infected with iv or intracranial inoculation of 1 x 10(4), 5 x 10(4) or 5 x 10(5) cfu of a clinical strain of S. apiospermum. Tissue burden reduction was determined in kidneys and brain 4 days after the infection. Efficacy of amphotericin B and liposomal amphotericin B (0.8 mg/kg/day intraperitoneally and 40 mg/kg/day iv, respectively) was evaluated in neutropenic mice infected iv or intracranially with 5 x 10(4) cfu. Survival was analysed with the log-rank test. Fungal burden values of different groups were compared using the Mann-Whitney U-test. In our model, intracranial infection produced a higher fungal load in the brain and a lower fungal load in the kidney than iv inoculation. Survival of animals infected intracranially and treated with amphotericin B or liposomal amphotericin B (mean survival time = 8.3 and 9.2 days, respectively) was not different from the control group (P=0.58 and 0.85, respectively). We have developed a murine model of cerebral scedosporiosis, which may be useful for studying various pathological aspects of this infection and evaluating new therapeutic approaches. Amphotericin B and liposomal amphotericin B were unable to resolve the infection.