Influence of Human Serum on the Postantifungal Effect of Four Antifungal Agents on Candida albicans

Chemotherapy ◽  
1996 ◽  
Vol 42 (4) ◽  
pp. 273-279 ◽  
Author(s):  
F. Mínguez ◽  
J.E. Lima ◽  
M.T. García ◽  
J. Prieto
Keyword(s):  
Candida Albicans ◽  
Human Serum ◽  
Antifungal Agents ◽  
Postantifungal Effect

scholarly journals Postantifungal Effects of Echinocandin, Azole, and Polyene Antifungal Agents against Candida albicans andCryptococcus neoformans

2000 ◽  
Vol 44 (4) ◽  
pp. 1108-1111 ◽  
Author(s):  
Erika J. Ernst ◽  
Michael E. Klepser ◽  
Michael A. Pfaller
Keyword(s):  
Candida Albicans ◽  
Cryptococcus Neoformans ◽  
Amphotericin B ◽  
Antifungal Agents ◽  
Postantifungal Effect

ABSTRACT The postantifungal effect (PAFE) of fluconazole, MK-0991, LY303366, and amphotericin B was determined against isolates of Candida albicans and Cryptococcus neoformans. Concentrations ranging from 0.125 to 4 times the MIC were tested following exposure to the antifungal for 0.25 to 1 h. Combinations of azole and echinocandin antifungals (MK-0991 and LY303366) were tested againstC. neoformans. Fluconazole displayed no measurable PAFE against Candida albicans or Cryptococcus neoformans, either alone or in combination with either echinocandin antifungal. MK-0991, LY303366, and amphotericin B displayed a prolonged PAFE of greater than 12 h againstCandida spp. when tested at concentrations above the MIC for the organism and 0 to 2 h when tested at concentrations below the MIC for the organism.

scholarly journals Influence of Human Serum on Antifungal Pharmacodynamics with Candida albicans

2001 ◽  
Vol 45 (7) ◽  
pp. 2018-2022 ◽  
Author(s):  
George G. Zhanel ◽  
David G. Saunders ◽  
Daryl J. Hoban ◽  
James A. Karlowsky
Keyword(s):  
Candida Albicans ◽  
Protein Binding ◽  
Human Serum ◽  
Amphotericin B ◽  
Reference Strain ◽  
Antifungal Agents ◽  
Low Protein ◽  
High Protein Binding ◽  
Fluconazole Resistant ◽  
Reduced Activity

ABSTRACT Antifungal susceptibilities (NCCLS, approved standard M27-A, 1997) were determined for the reference strain ATCC 90028 and 21 clinical isolates of Candida albicans with varying levels of fluconazole susceptibility using RPMI 1640 (RPMI) and 80% fresh human serum–20% RPMI (serum). Sixty-four percent (14 of 22) of the isolates tested demonstrated significant decreases (≥4-fold) in fluconazole MICs in the presence of serum, and the remaining eight isolates exhibited no change. Itraconazole and ketoconazole, two highly protein-bound antifungal agents, had MICs in serum that were increased or unchanged for 46% (10 of 22) and 41% (9 of 22) of the isolates, respectively. All 10 isolates tested against an investigational antifungal agent, LY303366, demonstrated significant increases in the MIC required in serum, while differences in amphotericin B MICs in the two media were not observed. Four of 10 isolates tested demonstrated fourfold higher flucytosine MICs in serum than in RPMI. Postantifungal effects (PAFEs) and 24-h kill curves were determined by standard methods for selected isolates. At the MIC, fluconazole, itraconazole, ketoconazole, flucytosine, and LY303366 kill curves and PAFEs in RPMI were similar to those in serum. Isolates of fluconazole-resistantC. albicans required lower MICs in serum than in RPMI, without relative increases in fungal killing or PAFEs. Isolates tested against amphotericin B demonstrated significantly reduced killing and shorter PAFEs in serum than in RPMI without observable changes in MIC. In conclusion, antifungal pharmacodynamics in RPMI did not consistently predict antifungal activity in serum for azoles and amphotericin B. Generally speaking, antifungal agents with high protein binding exhibited some form of reduced activity (MIC, killing, or PAFE) in the presence of serum compared to those with low protein binding.

scholarly journals Sublethal Injury and Resuscitation of Candida albicans after Amphotericin B Treatment

2003 ◽  
Vol 47 (4) ◽  
pp. 1200-1206 ◽  
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.

scholarly journals Kinetic characterisation and inhibitor sensitivity of Candida albicans and Candida auris recombinant AOX expressed in a self-assembled proteoliposome system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alice C. Copsey ◽  
Mario R. O. Barsottini ◽  
Benjamin May ◽  
Fei Xu ◽  
Mary S. Albury ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Future Development ◽  
Therapeutic Target ◽  
Fungicide Resistance ◽  
Alternative Oxidase ◽  
Antifungal Agents ◽  
Candida Auris ◽  
Novel Treatments ◽  
Membrane Bound ◽  
Self Assembled

AbstractCandidemia caused by Candida spp. is a serious threat in hospital settings being a major cause of acquired infection and death and a possible contributor to Covid-19 mortality. Candidemia incidence has been rising worldwide following increases in fungicide-resistant pathogens highlighting the need for more effective antifungal agents with novel modes of action. The membrane-bound enzyme alternative oxidase (AOX) promotes fungicide resistance and is absent in humans making it a desirable therapeutic target. However, the lipophilic nature of the AOX substrate (ubiquinol-10) has hindered its kinetic characterisation in physiologically-relevant conditions. Here, we present the purification and expression of recombinant AOXs from C. albicans and C. auris in a self-assembled proteoliposome (PL) system. Kinetic parameters (Km and Vmax) with respect to ubiquinol-10 have been determined. The PL system has also been employed in dose–response assays with novel AOX inhibitors. Such information is critical for the future development of novel treatments for Candidemia.

scholarly journals CaNdt80 Is Involved in Drug Resistance in Candida albicans by Regulating CDR1

2004 ◽  
Vol 48 (12) ◽  
pp. 4505-4512 ◽  
Author(s):  
Chia-Geun Chen ◽  
Yun-Liang Yang ◽  
Hsin-I Shih ◽  
Chia-Li Su ◽  
Hsiu-Jung Lo
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Drug Resistance ◽  
Candida Albicans ◽  
Type Strain ◽  
Antifungal Agents ◽  
Wild Type Strain ◽  
Efflux Pump ◽  
Antifungal Drugs ◽  
Galactosidase Activity ◽  
Wild Type

ABSTRACT Overexpression of CDR1, an efflux pump, is one of the major mechanisms contributing to drug resistance in Candida albicans. CDR1 p-lacZ was constructed and transformed into a Saccharomyces cerevisiae strain so that the lacZ gene could be used as the reporter to monitor the activity of the CDR1 promoter. Overexpression of CaNDT80, the C. albicans homolog of S. cerevisiae NDT80, increases the β-galactosidase activity of the CDR1 p-lacZ construct in S. cerevisiae. Furthermore, mutations in CaNDT80 abolish the induction of CDR1 expression by antifungal agents in C. albicans. Consistently, the Candt80/Candt80 mutant is also more susceptible to antifungal drugs than the wild-type strain. Thus, the gene for CaNdt80 may be the first gene among the regulatory factors involved in drug resistance in C. albicans whose function has been identified.

scholarly journals Kinetic Patterns of Candida albicans Germ Tube Antibody in Critically Ill Patients: Influence on Mortality

2009 ◽  
Vol 16 (10) ◽  
pp. 1527-1528 ◽  
Author(s):  
Rafael Zaragoza ◽  
Javier Pemán ◽  
Guillermo Quindós ◽  
Jose R. Iruretagoyena ◽  
María S. Cuétara ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Intensive Care ◽  
Intensive Care Units ◽  
Critically Ill ◽  
Critically Ill Patients ◽  
Germ Tube ◽  
Antifungal Agents ◽  
Mortality Rates ◽  
Antifungal Treatment ◽  
Lower Mortality

ABSTRACT The influence of kinetic patterns of Candida albicans germ tube antibodies (CAGTA) on mortality was analyzed in six intensive care units. Statistically significant lower mortality rates were found in patients with patterns of increasing CAGTA titers who had been treated with antifungal agents. Thus, antifungal treatment should be considered when CAGTA titers are increasing in critically ill patients.

scholarly journals Candida albicans Sterol C-14 Reductase, Encoded by the ERG24 Gene, as a Potential Antifungal Target Site

2002 ◽  
Vol 46 (4) ◽  
pp. 947-957 ◽  
Author(s):  
N. Jia ◽  
B. Arthington-Skaggs ◽  
W. Lee ◽  
C. A. Pierson ◽  
N. D. Lees ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Fungal Pathogens ◽  
Antifungal Agents ◽  
Fungal Infections ◽  
Brefeldin A ◽  
Agricultural Applications ◽  
Mouse Model System ◽  
Cellular Inhibitors ◽  
Germ Tubes ◽  
Doubling Times

ABSTRACT The incidence of fungal infections has increased dramatically, which has necessitated additional and prolonged use of the available antifungal agents. Increased resistance to the commonly used antifungal agents, primarily the azoles, has been reported, thus necessitating the discovery and development of compounds that would be effective against the major human fungal pathogens. The sterol biosynthetic pathway has proved to be a fertile area for antifungal development, and steps which might provide good targets for novel antifungal development remain. The sterol C-14 reductase, encoded by the ERG24 gene, could be an effective target for drug development since the morpholine antifungals, inhibitors of Erg24p, have been successful in agricultural applications. The ERG24 gene of Candida albicans has been isolated by complementation of a Saccharomyces cerevisiae erg24 mutant. Both copies of the C. albicans ERG24 gene have been disrupted by using short homologous regions of the ERG24 gene flanking a selectable marker. Unlike S. cerevisiae, the C. albicans ERG24 gene was not required for growth, but erg24 mutants showed several altered phenotypes. They were demonstrated to be slowly growing, with doubling times at least twice that of the wild type. They were also shown to be significantly more sensitive to an allylamine antifungal and to selected cellular inhibitors including cycloheximide, cerulenin, fluphenazine, and brefeldin A. The erg24 mutants were also slightly resistant to the azoles. Most importantly, erg24 mutants were shown to be significantly less pathogenic in a mouse model system and failed to produce germ tubes upon incubation in human serum. On the basis of these characteristics, inhibitors of Erg24p would be effective against C. albicans.

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