Efficient treatment of murine systemic infection with Candida albicans
 using amphotericin B incorporated in nanosize range particles (emulsomes)

ABSTRACT The interaction between fluconazole (Flu) and amphotericin B (AmB) was evaluated in a murine model of systemic candidiasis for one Flu-susceptible strain (MIC, 0.5 μg/ml), two strains with intermediate Flu resistance (Flu mid-resistant strains) (MIC, 64 and 128 μg/ml), and one highly Flu-resistant strain (MIC, 512 μg/ml) ofCandida albicans. Differences in fungal densities in kidneys of infected mice after 24 h of therapy and in survival rates at 62 days of mice treated with an antifungal drug or a combination of antifungal drugs for 4 days were compared. For the Flu-susceptible and Flu mid-resistant strains, the combination of Flu and AmB was antagonistic, as shown by both quantitative culture results and survival. The interaction was additive for the highly Flu-resistant strain. These results suggest that the combination of Flu and AmB should be used with caution in infections due to fungi that are usually susceptible to both antifungal agents and as empirical antifungal drug therapy.

Download Full-text

Antifungal effect of Hevea brasiliensis latex with various fungi. Its synergistic action with amphotericin B against Candida albicans - Antimyzetische Wirkung von Hevea brasiliensis-Latex auf verschiedene Pilze und seine synergistische Wirkung mit Amphotericin B auf Candida albicans

Mycoses ◽

10.1046/j.1439-0507.2002.d01-134.x ◽

2002 ◽

Vol 45 (11-12) ◽

pp. 476-481

Author(s):

R. Giordani ◽

P. Regli ◽

J. Buc

Keyword(s):

Candida Albicans ◽

Amphotericin B ◽

Hevea Brasiliensis ◽

Synergistic Action ◽

Antifungal Effect

Download Full-text

Unaltered Fungal Burden and Lethality in Human CEACAM1-Transgenic Mice During Candida albicans Dissemination and Systemic Infection

Frontiers in Microbiology ◽

10.3389/fmicb.2019.02703 ◽

2019 ◽

Vol 10 ◽

Cited By ~ 1

Author(s):

Esther Klaile ◽

Mario M. Müller ◽

Cristina Zubiría-Barrera ◽

Saskia Brehme ◽

Tilman E. Klassert ◽

...

Keyword(s):

Candida Albicans ◽

Transgenic Mice ◽

Systemic Infection ◽

Fungal Burden

Download Full-text

Sublethal Injury and Resuscitation of Candida albicans after Amphotericin B Treatment

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.47.4.1200-1206.2003 ◽

2003 ◽

Vol 47 (4) ◽

pp. 1200-1206 ◽

Cited By ~ 13

Author(s):

Robert S. Liao ◽

Robert P. Rennie ◽

James A. Talbot

Keyword(s):

Cell Death ◽

Candida Albicans ◽

Amphotericin B ◽

Antifungal Agents ◽

Sybr Green ◽

Sequential Treatment ◽

Tetrazolium Salt ◽

Fungal Cell ◽

Sublethal Injury

ABSTRACT Amphotericin B treatment was previously shown to inhibit Candida albicans reproduction and reduce the fluorescence of vitality-specific dyes without causing a corresponding increase in the fluorescence of the mortality-specific dyes bis-(1,3-dibutylbarbituric acid)trimethine oxonol and SYBR Green Ι. In the present study, we have confirmed these results and have shown that the numbers of CFU are reduced by 99.9% by treatment with 0.5 μg of amphotericin B per ml for 10 h at 35°C. This reduction was not due to fungal cell death. First, the level of reduction of the tetrazolium salt 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide increased in the presence of concentrations of amphotericin B that caused greater than 90% reductions in the numbers of CFU. Second, fungal cells treated with amphotericin B at a concentration of 0.5 μg/ml were resuscitated by further incubation at 22°C for 15 h in the continued presence of amphotericin B. Third, recovery of the ability to replicate was prevented by sequential treatment with 20 μg of miconazole per ml, which also increased the fluorescence of mortality-specific dyes to near the maximal levels achieved with 0.9 μg of amphotericin B per ml. Sequential treatment with fluconazole and flucytosine did not increase the levels of staining with the mortality-specific dyes. Itraconazole was less effective than ketoconazole, which was less effective than miconazole. The practice of equating the loss of the capacity of C. albicans to form colonies with fungal cell death may give incorrect results in assays with amphotericin B, and the results of assays with caution with other antifungal agents that are lipophilic or that possess significant postantifungal effects may need to be interpreted.

Download Full-text

Identification and Characterization of TUP1-Regulated Genes in Candida albicans

Genetics ◽

10.1093/genetics/156.1.31 ◽

2000 ◽

Vol 156 (1) ◽

pp. 31-44 ◽

Cited By ~ 7

Author(s):

Burkhard R Braun ◽

W Steven Head ◽

Ming X Wang ◽

Alexander D Johnson

Keyword(s):

Candida Albicans ◽

Systemic Infection ◽

Subtractive Hybridization ◽

Filamentous Growth ◽

Surface Proteins ◽

Infection Model ◽

Ferric Reductase ◽

Pathogenesis Related Protein ◽

Plant Pathogenesis ◽

Rnase T2

Abstract TUP1 encodes a transcriptional repressor that negatively controls filamentous growth in Candida albicans. Using subtractive hybridization, we identified six genes, termed repressed by TUP1 (RBT), whose expression is regulated by TUP1. One of the genes (HWP1) has previously been characterized, and a seventh TUP1-repressed gene (WAP1) was recovered due to its high similarity to RBT5. These genes all encode secreted or cell surface proteins, and four out of the seven (HWP1, RBT1, RBT5, and WAP1) encode putatively GPI-modified cell wall proteins. The remaining three, RBT2, RBT4, and RBT7, encode, respectively, an apparent ferric reductase, a plant pathogenesis-related protein (PR-1), and a putative secreted RNase T2. The expression of RBT1, RBT4, RBT5, HWP1, and WAP1 was induced in wild-type cells during the switch from the yeast form to filamentous growth, indicating the importance of TUP1 in regulating this process and implicating the RBTs in hyphal-specific functions. We produced knockout strains in C. albicans for RBT1, RBT2, RBT4, RBT5, and WAP1 and detected no phenotypes on several laboratory media. However, two animal models for C. albicans infection, a rabbit cornea model and a mouse systemic infection model, revealed that rbt1Δ and rbt4Δ strains had significantly reduced virulence. TUP1 appears, therefore, to regulate many genes in C. albicans, a significant fraction of which are induced during filamentous growth, and some of which participate in pathogenesis.

Download Full-text

Dectin-2-Targeted Antifungal Liposomes Exhibit Enhanced Efficacy

mSphere ◽

10.1128/msphere.00715-19 ◽

2019 ◽

Vol 4 (5) ◽

Cited By ~ 1

Author(s):

Suresh Ambati ◽

Emma C. Ellis ◽

Jianfeng Lin ◽

Xiaorong Lin ◽

Zachary A. Lewis ◽

...

Keyword(s):

Candida Albicans ◽

Aspergillus Fumigatus ◽

Effective Dose ◽

Cryptococcus Neoformans ◽

Amphotericin B ◽

Antifungal Drugs ◽

Extracellular Matrices ◽

Content Type ◽

Order Of Magnitude ◽

Life Threatening

ABSTRACT Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus cause life-threatening candidiasis, cryptococcosis, and aspergillosis, resulting in several hundred thousand deaths annually. The patients at the greatest risk of developing these life-threatening invasive fungal infections have weakened immune systems. The vulnerable population is increasing due to rising numbers of immunocompromised individuals as a result of HIV infection or immunosuppressed individuals receiving anticancer therapies and/or stem cell or organ transplants. While patients are treated with antifungals such as amphotericin B, all antifungals have serious limitations due to lack of sufficient fungicidal effect and/or host toxicity. Even with treatment, 1-year survival rates are low. We explored methods of increasing drug effectiveness by designing fungicide-loaded liposomes specifically targeted to fungal cells. Most pathogenic fungi are encased in cell walls and exopolysaccharide matrices rich in mannans. Dectin-2 is a mammalian innate immune membrane receptor that binds as a dimer to mannans and signals fungal infection. We coated amphotericin-loaded liposomes with monomers of Dectin-2’s mannan-binding domain, sDectin-2. sDectin monomers were free to float in the lipid membrane and form dimers that bind mannan substrates. sDectin-2-coated liposomes bound orders of magnitude more efficiently to the extracellular matrices of several developmental stages of C. albicans, C. neoformans, and A. fumigatus than untargeted control liposomes. Dectin-2-coated amphotericin B-loaded liposomes reduced the growth and viability of all three species more than an order of magnitude more efficiently than untargeted control liposomes and dramatically decreased the effective dose. Future efforts focus on examining pan-antifungal targeted liposomal drugs in animal models of fungal diseases. IMPORTANCE Invasive fungal diseases caused by Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus have mortality rates ranging from 10 to 95%. Individual patient costs may exceed $100,000 in the United States. All antifungals in current use have serious limitations due to host toxicity and/or insufficient fungal cell killing that results in recurrent infections. Few new antifungal drugs have been introduced in the last 2 decades. Hence, there is a critical need for improved antifungal therapeutics. By targeting antifungal-loaded liposomes to α-mannans in the extracellular matrices secreted by these fungi, we dramatically reduced the effective dose of drug. Dectin-2-coated liposomes loaded with amphotericin B bound 50- to 150-fold more strongly to C. albicans, C. neoformans, and A. fumigatus than untargeted liposomes and killed these fungi more than an order of magnitude more efficiently. Targeting drug-loaded liposomes specifically to fungal cells has the potential to greatly enhance the efficacy of most antifungal drugs.

Download Full-text