Murine Model Of Disseminated Infection Research Articles

Virulence of Sporothrix luriei in a Murine Model of Disseminated Infection

Sporothrix luriei is a rare fungus causing sporotrichosis in humans. The virulence of this fungus was evaluated in a murine model of disseminated infection. Mice were challenged intravenously with two different inocula (2×10(5) and 2×10(7)CFU/animals) but only the highest one was able to kill the animals. Infected mice died between days 12 and 16, liver and spleen being the most affected organs. In the infected tissues, a massive infiltration of fungal cells and phagocytes were observed, but not the typical "eyeglass" cells described in infected human tissue.

Anidulafungin in Treatment of Experimental Invasive Infection by Candida parapsilosis: In Vitro Activity, (1→3)-β- d -Glucan and Mannan Serum Levels, Histopathological Findings, and In Vivo Efficacy

We have evaluated the in vitro activity of anidulafungin (AFG) against 31 strains of Candida parapsilosis sensu stricto by using broth microdilution, disk diffusion, and minimal fungicidal concentration (MFC) determination procedures. The two first methods showed a high level of activity of the drug, while MFCs were 1 to 5 dilutions higher than their corresponding MICs. To assess if MICs were predictive of in vivo outcomes, six strains representing different AFG MICs (0.12 to 2 μg/ml) were tested in a murine model of disseminated infection treated with different doses of the drug (1, 5, or 10 mg/kg of body weight). AFG was able to prolong the survival of mice infected with all the strains tested but was able to reduce the tissue burden of those mice infected only with the strains that showed the lowest MIC (0.12 μg/ml).

Efficacy of anidulafungin against Aspergillus niger in vitro and in vivo

In this study, anidulafungin (AFG) showed high in vitro activity against 10 isolates of Aspergillus niger by broth microdilution and disk diffusion methods. The efficacy of AFG at 1, 5 and 10mg/kg was tested against six of the isolates in a murine model of disseminated infection. AFG was able to reduce mortality, showing survival rates of 70–100%, 60–100% and 30–60% in mice treated with AFG at 10, 5 and 1mg/kg, respectively. AFG also showed a dose–response efficacy in reducing tissue burden in kidneys and spleen. A parallel experiment demonstrated that administration of AFG did not reduce serum concentrations of galactomannan in mice. Histopathological studies confirmed the efficacy of AFG.

In Vitro Activity and In Vivo Efficacy of Anidulafungin in Murine Infections by Aspergillus flavus

Anidulafungin (AFG) showed high activity against 27 strains of Aspergillus flavus by use of broth microdilution and disk diffusion methods. This drug was effective in vivo in a murine model of disseminated infection with five isolates tested. AFG was able to prolong survival and reduce tissue burden of infected mice but not able to reduce galactomannan serum concentrations. The AFG serum levels were above the corresponding minimum effective concentrations (MEC) for all of the strains tested.

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.

Treatment of murine Fusarium verticillioides infection with liposomal amphotericin B plus terbinafine

Using a murine model of disseminated infection by Fusarium verticillioides, the efficacy of liposomal amphotericin (L-AmB) B at 10 mg/kg body weight once daily and terbinafine (TRB) at 150 mg/kg body weight twice daily, alone and in combination, was evaluated. The combination of L-AmB with TRB was the only treatment able to prolong survival and to reduce fungal loads in the spleen and kidneys of mice infected with either strain of F. verticillioides used. The results suggest that this combination may have a role in the treatment of F. verticillioides infection.

Combined Therapy Against Murine-Disseminated Infection by Fusarium verticillioides

Using a murine model of disseminated infection by two strains of Fusarium verticillioides, we have evaluated the efficacy of high doses of amphotericin B (AMB) (3 mg/kg of body weight/day), voriconazole (VRC) (60 mg/kg of body weight/day), posaconazole (PSC) (100 mg/kg of body weight/day), and the combinations of AMB plus VRC or PSC. In general, our results were very modest. Neither combination was superior to the respective monotherapies. VRC alone and in combination with AMB was able to prolong survival but not to reduce tissue burden, and AMB plus PSC was able to reduce fungal load in organs but not to prolong survival.

Efficacy of voriconazole in a murine model of invasive paecilomycosis

We studied the efficacy of voriconazole (VRC) and amphotericin B (AMB) in an immunosuppressed murine model of disseminated infection by two strains of Paecilomyces lilacinus. Mice were treated with VRC 60 mg/kg/day orally or AMB 3 mg/kg/day intraperitoneally, beginning 1 day after infection and continuing for 9 days. To avoid rapid clearance of VRC, animals receiving VRC and the control group were given grapefruit juice instead of water. VRC significantly prolonged survival with respect to the group treated with AMB and the control group for both strains ( P = 0.005 and P < 0.0001, respectively, for strain FMR 5522; and P = 0.0002 and P < 0.0001, respectively, for strain FMR 8252). VRC reduced the fungal load in the spleen, kidneys and liver of infected mice for both strains tested. Survival of mice challenged with strain FMR 8252 treated with AMB did not differ from that of the control group ( P = 0.223), being worse than that of the mice treated with VRC ( P = 0.0002). AMB was not able to reduce the tissue burden in any organ with respect to the control group for both strains studied.

Effects of double and triple combinations of antifungal drugs in a murine model of disseminated infection by Scedosporium prolificans.

We have evaluated the efficacies of micafungin, amphotericin B, and voriconazole, alone and in double and triple combinations, in a murine model of systemic infection by Scedosporium prolificans. Micafungin combined with voriconazole or amphotericin B was the most effective, these being the only treatments able to prolong survival and to reduce the fungal load in the kidneys and brain. Triple combinations of these drugs did not improve the results obtained with double combinations.

Combined antifungal therapy in a murine model of disseminated infection byCladophialophora bantiana

We tested ten day courses of amphotericin B (AMB), micafungin (MFG), voriconazole (VRC), flucytosine (5FC) and posaconazole (PSC) alone and in double or triple combinations in the treatment of disseminated infections caused by Cladophialophora bantiana in a murine model. Animals were monitored for survival for 40 days. We found that PSC at 100 mg/kg or 5FC at 180 mg/kg prolonged survival over controls. The combinations PSC+MFG and PSC+5FC improved survival compared to MFG and 5FC alone, but were not superior to PSC alone. The triple combination of PSC+MFG+5FC improved the survival with respect to both the control group and the component monotherapies, but all the animals died during the experiment. When treatment with this triple therapy was extended up to 30 days, half of the animals survived for at least 10 months. Combination therapy with the three drugs (PSC, MFG and 5FC) appears to be a promising option for the treatment of C. bantiana infections.

Combined therapy in treatment of murine infection by Fusarium solani

We evaluated the efficacy of voriconazole, amphotericin B and micafungin alone and combined in a murine model of disseminated infection by Fusarium solani. Immunosuppressed mice were treated with voriconazole at 60 mg/kg/day, amphotericin B at 3 mg/kg/day, micafungin at 10 mg/kg/day or combinations of these antifungal drugs. For survival studies, treatment began 1 day after infection and continued for 10 days. For tissue burden studies, animals were sacrificed on day 6 of the treatment and the fungal load in the kidneys and spleens was measured. The experiments were carried out using two different clinical strains of F. solani. Only the combination of voriconazole plus amphotericin B prolonged the survival of the mice versus the controls for the two strains tested. However, this combination only reduced tissue burden in the kidney and spleen of mice infected by one strain. The other treatments were clearly less effective. Voriconazole plus amphotericin B may have a role in the treatment of fusariosis.

Efficacy of a new formulation of amphotericin B in a murine model of disseminated infection by Candida glabrata

Amphotericin B poly-aggregates are a new formulation of amphotericin B, which can be obtained cheaply. In this study, we tested the efficacy of this new formulation for treating a disseminated infection by Candida glabrata in a murine model. Mice were rendered neutropenic by intraperitoneal cyclophosphamide and intravenous 5-fluorouracil administration and infected intravenously with 2 x 10(8) cfu of C. glabrata. The efficacy of the new formulation of amphotericin B was evaluated by survival and tissue burden studies. The experiments were repeated using three different clinical strains of C. glabrata. Amphotericin B poly-aggregates showed an efficacy similar to that of amphotericin B deoxycholate and liposomal amphotericin B in the treatment of a disseminated murine infection by C. glabrata.

Activity of aminocandin (IP960) compared with amphotericin B and fluconazole in a neutropenic murine model of disseminated infection caused by a fluconazole-resistant strain of Candida tropicalis

To compare the activity of aminocandin (IP960), a new echinocandin with broad-spectrum in vitro activity against Aspergillus and Candida spp., with that of amphotericin B and fluconazole in a temporarily immunocompromised murine model of disseminated candidiasis. Mice were rendered neutropenic with cyclophosphamide and infected intravenously 3 days later with a fluconazole-resistant Candida tropicalis strain. Mice were treated with intraperitoneal amphotericin B (5 mg/kg/dose), oral fluconazole (50 mg/kg/dose), intravenous aminocandin (0.1--5 mg/kg/dose) or solvent control for 9 days. Mice were observed for survival and survivors were sacrificed 11 days post-infection. Kidneys, liver, brain and lungs were removed for semi-quantitative culture. Control mice had 90--100% mortality. After infection with C. tropicalis, aminocandin 2.5 and 5 mg/kg/day and amphotericin B yielded 80% survival; aminocandin 1 mg/kg/day yielded 70% survival; aminocandin 0.25 and 0.1 mg/kg/day yielded 30% and 20% survival, respectively; and fluconazole 50 mg/kg/day and control regimens yielded 10% and 0--10% survival, respectively. Aminocandin 2.5 and 5.0 mg/kg/day and amphotericin B were superior in reducing mortality compared with aminocandin 0.25 and 0.1 mg/kg/day, fluconazole and controls (P<0.047). The only regimen to reduce organ burdens below detectable levels was amphotericin B, which cleared 40% of mice. All organ burdens in the aminocandin 1.0, 2.5 and 5.0 mg/kg/day and amphotericin B regimens were significantly lower than other groups (P<0.02). The data demonstrate that aminocandin at doses of >or=1.0 mg/kg/day is as effective as amphotericin B at improving survival and reducing organ burdens in this murine model of disseminated C. tropicalis.

Efficacy of Micafungin in Combination with Other Drugs in a Murine Model of Disseminated Trichosporonosis

Using a murine model of disseminated infection caused by Trichosporon asahii, we have evaluated the efficacies of amphotericin B (AMB; 1 mg/kg of body weight/day), fluconazole (FLC; 20 mg/kg/twice a day), and micafungin (MFG; 5 mg/kg/twice a day). We tested these drugs alone and in combination (MFG with AMB and MFG with FLC). MFG with AMB showed a synergistic effect and demonstrated a higher degree of efficacy in prolonging survival and reducing the kidney fungal burden than either agent alone. The combination MFG with FLC was able to reduce significantly the kidney fungal burden in comparison to that achieved with either drug administered alone.

Telomere length control and transcriptional regulation of subtelomeric adhesins in Candida glabrata

The pathogenic yeast Candida glabrata is able to bind in vitro to human epithelial cells. This interaction depends on expression of the adhesin Epa1p. The genome contains a number of EPA1 paralogues which localize to the subtelomeric regions of the C. glabrata. We have identified three hyperadherent mutants of C. glabrata. The first has an insertion adjacent to EPA7, an EPA1-related adhesin. The others disrupt the SIR3 and RIF1 genes of C. glabrata. We show that SIR3 and RIF1 are required for subtelomeric silencing in C. glabrata and that RIF1 regulates telomere length in C. glabrata. We show that the hyperadherent phenotype of the sir3Delta and rif1Delta deletion strains depends primarily on derepression of two novel members of the EPA gene family -EPA6 and EPA7. The sir3Delta and rif1Delta mutants show increased colonization of the kidney in a murine model of disseminated infection and this hypercolonization depends, at least in part, on derepression of EPA6 and EPA7. The analysis here is the first evidence that multiple EPA genes encode adhesins and demonstrates that transcription of at least two of these adhesins is regulated by subtelomeric silencing.

Antifungal activities of posaconazole and granulocyte-macrophage colony-stimulating factor ex vivo and in mice with disseminated infection due to Scedosporium prolificans.

Invasive infection due to Scedosporium prolificans is characterized by drug resistance and a high rate of mortality. The effects of posaconazole (POS), an investigational antifungal triazole, murine granulocyte-macrophage colony-stimulating factor (GM-CSF), and their combination against S. prolificans were evaluated ex vivo and in a newly developed murine model of disseminated infection due to this organism. When POS was combined with polymorphonuclear leukocytes from untreated or GM-CSF-treated mice (P < 0.01) ex vivo, it had increased activity in terms of the percentage of hyphal damage. Immunocompetent BALB/c mice were infected with 4 x 10(4) conidia of S. prolificans via the lateral tail vein. At 24 h postinfection the mice were treated with GM-CSF (5 microg/kg of body weight/day subcutaneously), POS (50 mg/kg/day by gavage), both agents, or saline only. Half of the brain, lung, liver, and kidney from each animal were cultured; and the other half of each organ was processed for histopathology. The mean survival times were 7.0 +/- 0.3 days for the controls, 7.4 +/- 0.4 days for POS-treated mice, 8.0 +/- 0.3 days for GM-CSF-treated mice (P = 0.08 compared with the results for the controls), and 7.3 +/- 0.3 days for POS-GM-CSF-treated mice. Fungal burdens (determined as the numbers of CFU per gram of tissue) were found in descending orders of magnitude in the kidneys, brains, livers, and lungs. The burdens were significantly reduced in the brains of GM-CSF-treated mice (P < 0.05) and the livers of POS-treated mice (P < 0.05). The numbers of lesions in the organs closely corresponded to the fungal burdens. GM-CSF tended to prolong survival (P = 0.08 compared with the results for the controls). While the combination of POS and GM-CSF showed enhanced activity ex vivo, it did not increase the activities of the two agents against this highly refractory filamentous fungus in mice.

Activities of clarithromycin, ofloxacin, and clarithromycin plus ethambutol against Mycobacterium simiae in murine model of disseminated infection.

After 2 weeks of intravenous challenge with Mycobacterium simiae, ICR outbred mice were treated with clarithromycin, ofloxacin, or clarithromycin plus ethambutol for 4 weeks. All three therapy groups demonstrated a decrease in the level of infection in both the lungs and the spleen. There were no significant differences among the three treated groups in decreasing mycobacterial counts in the lungs; however, both ofloxacin and clarithromycin plus ethambutol were superior to clarithromycin alone in reducing the level of infection in the spleen. Results of the study suggest a potential role for these agents in the treatment of human M. simiae infection.