Influence of Human Serum on Antifungal Pharmacodynamics with Candida albicans

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.

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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.

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In Vitro Activities of Isavuconazole and Other Antifungal Agents against Candida Bloodstream Isolates

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01217-06 ◽

2007 ◽

Vol 51 (5) ◽

pp. 1818-1821 ◽

Cited By ~ 61

Author(s):

H. Seifert ◽

U. Aurbach ◽

D. Stefanik ◽

O. Cornely

Keyword(s):

Amphotericin B ◽

Antifungal Agents ◽

Tertiary Care ◽

Common Species ◽

University Hospital ◽

Phase Iii ◽

Highly Active ◽

Fluconazole Resistant ◽

Resistant Strains

ABSTRACT Isavuconazole is the active component of the new azole antifungal agent BAL8557, which is entering phase III clinical development. This study was conducted to compare the in vitro activities of isavuconazole and five other antifungal agents against 296 Candida isolates that were recovered consecutively from blood cultures between 1995 and 2004 at a tertiary care university hospital. Microdilution testing was done in accordance with CLSI (formerly NCCLS) guideline M27-A2 in RPMI-1640 MOPS (morpholinepropanesulfonic acid) broth. The antifungal agents tested were amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole, and isavuconazole. C. albicans was the most common species, representing 57.1% of all isolates. There was no trend found in favor of non-Candida albicans species over time. In terms of MIC50s, isavuconazole was more active (0.004 mg/liter) than amphotericin B (0.5 mg/liter), itraconazole (0.008 mg/liter), voriconazole (0.03 mg/liter), flucytosine (0.125 mg/liter), and fluconazole (8 mg/liter). For isavuconazole, MIC50s/MIC90s ranged from 000.2/0.004 mg/liter for C. albicans to 0.25/0.5 mg/liter for C. glabrata. Two percent of isolates (C. glabrata and C. krusei) were resistant to fluconazole; C. albicans strains resistant to fluconazole were not detected. There were only two isolates with MICs for isavuconazole that were >0.5 mg/liter: both were C. glabrata isolates, and the MICs were 2 and 4 mg/liter, respectively. In conclusion, isavuconazole is highly active against Candida bloodstream isolates, including fluconazole-resistant strains. It was more active than itraconazole and voriconazole against C. albicans and C. glabrata and appears to be a promising agent against systemic Candida infections.

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In Vitro Antifungal Activities of a Series of Dication-Substituted Carbazoles, Furans, and Benzimidazoles

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.42.10.2503 ◽

1998 ◽

Vol 42 (10) ◽

pp. 2503-2510 ◽

Cited By ~ 58

Author(s):

Maurizio Del Poeta ◽

Wiley A. Schell ◽

Christine C. Dykstra ◽

Susan K. Jones ◽

Richard R. Tidwell ◽

...

Keyword(s):

Antimicrobial Activity ◽

Candida Albicans ◽

Fusarium Solani ◽

Antifungal Agents ◽

Antifungal Drugs ◽

Inhibitory Compounds ◽

Wide Range ◽

Fluconazole Resistant ◽

Resistant Strains

ABSTRACT Aromatic dicationic compounds possess antimicrobial activity against a wide range of eucaryotic pathogens, and in the present study an examination of the structures-functions of a series of compounds against fungi was performed. Sixty-seven dicationic molecules were screened for their inhibitory and fungicidal activities againstCandida albicans and Cryptococcus neoformans. The MICs of a large number of compounds were comparable to those of the standard antifungal drugs amphotericin B and fluconazole. Unlike fluconazole, potent inhibitory compounds in this series were found to have excellent fungicidal activities. The MIC of one of the most potent compounds against C. albicans was 0.39 μg/ml, and it was the most potent compound against C. neoformans (MIC, ≤0.09 μg/ml). Selected compounds were also found to be active againstAspergillus fumigatus, Fusarium solani,Candida species other than C. albicans, and fluconazole-resistant strains of C. albicans and C. neoformans. Since some of these compounds have been safely given to animals, these classes of molecules have the potential to be developed as antifungal agents.

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Genotypic variation and antifungal susceptibilities of Candida pelliculosa clinical isolates

Journal of Medical Microbiology ◽

10.1099/jmm.0.45850-0 ◽

2005 ◽

Vol 54 (3) ◽

pp. 279-285 ◽

Cited By ~ 18

Author(s):

F Barchiesi ◽

A M Tortorano ◽

L Falconi Di Francesco ◽

A Rigoni ◽

A Giacometti ◽

...

Keyword(s):

Candida Albicans ◽

Drug Therapy ◽

Amphotericin B ◽

Antifungal Agents ◽

Yeast Species ◽

Genotypic Variation ◽

Optimal Drug ◽

Typing Methods ◽

Dna Types

At the Istituto Ricovero Cura Carattere Scientifico, Ospedale Maggiore di Milano, Italy, Candida pelliculosa accounted for 3.3 and 4.4 % of all Candida species other than Candida albicans collected during 1996 and 1998, respectively. Genetic variability was investigated by electrophoretic karyotyping and inter-repeat PCR, and the susceptibility to five antifungal agents of 46 strains isolated from 37 patients during these 2 years was determined. Combination of the two typing methods yielded 14 different DNA types. Although the majority of DNA types were randomly distributed among different units, one DNA type was significantly more common in patients hospitalized in a given unit compared with those from other wards (P = 0.034), whereas another DNA type was more frequently isolated in patients hospitalized during 1996 than in those hospitalized during 1998 (P = 0.002). Fluconazole, itraconazole and posaconazole MIC90 values were 16, 1 and 4 μg ml−1, respectively. All isolates but three were susceptible in vitro to flucytosine. All isolates were susceptible in vitro to amphotericin B. These data suggest that there are possible relationships among strains of C. pelliculosa, wards and time of isolation. Amphotericin B seems to be the optimal drug therapy in infections due to this yeast species.

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

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.44.4.1108-1111.2000 ◽

2000 ◽

Vol 44 (4) ◽

pp. 1108-1111 ◽

Cited By ~ 132

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.

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In Vitro Pharmacodynamic Properties of Three Antifungal Agents against Preformed Candida albicans Biofilms Determined by Time-Kill Studies

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.46.11.3634-3636.2002 ◽

2002 ◽

Vol 46 (11) ◽

pp. 3634-3636 ◽

Cited By ~ 183

Author(s):

Gordon Ramage ◽

Kacy VandeWalle ◽

Stefano P. Bachmann ◽

Brian L. Wickes ◽

José L. López-Ribot

Keyword(s):

Candida Albicans ◽

Amphotericin B ◽

Antifungal Agents ◽

Pharmacokinetic Properties ◽

Time Kill ◽

Candida Albicans Biofilms

ABSTRACT We have examined the in vitro activities of fluconazole, amphotericin B, and caspofungin against Candida albicans biofilms by time-kill methodology. Fluconazole was ineffective against biofilms. Killing of biofilm cells was suboptimal at therapeutic concentrations of amphotericin B. Caspofungin displayed the most effective pharmacokinetic properties, with ≥99% killing at physiological concentrations.

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In Vitro Susceptibilities of Candida dubliniensisIsolates Tested against the New Triazole and Echinocandin Antifungal Agents

Journal of Clinical Microbiology ◽

10.1128/jcm.37.3.870-872.1999 ◽

1999 ◽

Vol 37 (3) ◽

pp. 870-872 ◽

Cited By ~ 85

Author(s):

M. A. Pfaller ◽

S. A. Messer ◽

S. Gee ◽

S. Joly ◽

C. Pujol ◽

...

Keyword(s):

Amphotericin B ◽

Antifungal Agents ◽

Clinical Laboratory ◽

National Committee ◽

Mucosal Disease ◽

Fluconazole Resistant ◽

Resistant Strains ◽

Investigational Agents ◽

Multidrug Resistance Transporters

Candida dubliniensis is a newly recognized fungal pathogen causing mucosal disease in AIDS patients. Although preliminary studies indicate that most strains of C. dubliniensis are susceptible to established antifungal agents, fluconazole-resistant strains have been detected. Furthermore, fluconazole-resistant strains are easily derived in vitro, and these strains exhibit increased expression of multidrug resistance transporters, especially MDR1. Because of the potential for the development of resistant strains of C. dubliniensis, it is prudent to explore the in vitro activities of several of the newer triazole and echinocandin antifungals against isolates of C. dubliniensis. In this study we tested 71 isolates of C. dubliniensis against the triazoles BMS-207147, Sch 56592, and voriconazole and a representative of the echinocandin class of antifungal agents, MK-0991. We compared the activities of these agents with those of the established antifungal agents fluconazole, itraconazole, amphotericin B, and 5-fluorocytosine (5FC) by using National Committee for Clinical Laboratory Standards microdilution reference methods. Our findings indicate that the vast majority of clinical isolates of C. dubliniensis are highly susceptible to both new and established antifungal agents. Strains with decreased susceptibilities to fluconazole remained susceptible to the investigational agents as well as to amphotericin B and 5FC. The increased potencies of the new triazole and echinocandin antifungal agents may provide effective therapeutic options for the treatment of infections due to C. dubliniensis.

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Combination of antifungal drugs and protease inhibitors prevent Candida albicans biofilm formation and disrupt mature biofilms

10.1101/2020.02.11.945030 ◽

2020 ◽

Author(s):

Matthew B. Lohse ◽

Megha Gulati ◽

Charles S. Craik ◽

Alexander D. Johnson ◽

Clarissa J. Nobile

Keyword(s):

Candida Albicans ◽

Protease Inhibitors ◽

Amphotericin B ◽

Biofilm Formation ◽

Antifungal Agents ◽

Antifungal Drugs ◽

Aspartyl Protease ◽

Abiotic Surfaces ◽

Drug Concentrations ◽

Aspartyl Protease Inhibitors

AbstractBiofilms formed by the fungal pathogen Candida albicans are resistant to many of the antifungal agents commonly used in the clinic. Previous reports suggest that protease inhibitors, specifically inhibitors of aspartyl proteases, could be effective antibiofilm agents. We screened three protease inhibitor libraries, containing a total of 80 compounds for the abilities to prevent C. albicans biofilm formation and to disrupt mature biofilms. The compounds were screened individually and in the presence of subinhibitory concentrations of the most commonly prescribed antifungal agents for Candida infections: fluconazole, amphotericin B, or caspofungin. Although few of the compounds affected biofilms on their own, seven aspartyl protease inhibitors inhibited biofilm formation when combined with amphotericin B or caspofungin. Furthermore, nine aspartyl protease inhibitors disrupted mature biofilms when combined with caspofungin. These results suggest that the combination of standard antifungal agents together with specific protease inhibitors may be useful in the prevention and treatment of C. albicans biofilm infections.ImportanceCandida albicans is one of the most common pathogens of humans. C. albicans forms biofilms, structured communities of cells several hundred microns thick, on both biotic and abiotic surfaces. These biofilms are typically resistant to antifungal drugs at the concentrations that are normally effective against free-floating cells, thus requiring treatment with higher drug concentrations that often have significant side effects. Here, we show that certain combinations of existing antifungal agents with protease inhibitors, including several drugs already commonly used to treat HIV patients, are effective at inhibiting biofilm formation by C. albicans and/or at disrupting mature C. albicans biofilms.

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Isolation and characterization of fluconazole- and amphotericin B-resistant Candida albicans from blood of two patients with leukemia.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.41.1.196 ◽

1997 ◽

Vol 41 (1) ◽

pp. 196-199 ◽

Cited By ~ 149

Author(s):

F S Nolte ◽

T Parkinson ◽

D J Falconer ◽

S Dix ◽

J Williams ◽

...

Keyword(s):

Candida Albicans ◽

Amphotericin B ◽

High Dose ◽

Clinical Settings ◽

Desaturase Gene ◽

Isolation And Characterization ◽

Fluconazole Resistant ◽

Resistant Strains ◽

Fluconazole Prophylaxis

Infections with fluconazole-resistant Candida albicans isolate have rarely been described in clinical settings other than oropharyngeal candidiasis in patients with late-stage AIDS. We report on two patients with leukemia who developed fungemia caused by fluconazole-resistant C. albicans after receiving fluconazole prophylaxis (400 mg/day) and empiric amphotericin B therapy (0.5 mg/kg of body weight per day). The fluconazole MICs for the isolates were > or = 64 micrograms/ml, and the isolates were resistant to other azoles and had membrane sterol changes consistent with a mutation in the delta 5,6-sterol desaturase gene. The lack of ergosterol in the cytoplasmic membrane of the fluconazole-resistant strains also imparted resistance to amphotericin B. Both patients were successfully treated with high-dose amphotericin B (1 to 1.25 mg/kg/day) and flucytosine (150 mg/kg/day).

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In vitroactivities of antifungals alone and in combination with tigecycline againstCandida albicansbiofilms

PeerJ ◽

10.7717/peerj.5263 ◽

2018 ◽

Vol 6 ◽

pp. e5263 ◽

Cited By ~ 6

Author(s):

Mayram Hacioglu ◽

Ayse Seher Birteksoz Tan ◽

Sibel Dosler ◽

Nese Inan ◽

Gulten Otuk

Keyword(s):

Candida Albicans ◽

Amphotericin B ◽

Biofilm Formation ◽

Antifungal Agents ◽

Synergistic Effects ◽

Planktonic Cells ◽

Effective Agent ◽

Highly Active ◽

Highly Effective ◽

Anti Fungal

BackgroundCandidamay form biofilms, which are thought to underlie the most recalcitrant infections.MethodsIn this study, activities of antifungal agents alone and in combination with tigecycline against planktonic cells and mature and developing biofilms ofCandida albicansisolates were evaluated.ResultsAmphotericin B and echinocandins were found to be the most effective agents against mature biofilms, whereas the least effective agent was fluconazole. Furthermore, the most effective anti-fungal monotherapies against biofilm formation were amphotericin B and anidulafungin, and the least effective monotherapy was itraconazole. The combination of tigecycline and amphotericin B yielded synergistic effects, whereas combinations containing itraconazole yielded antagonist effects against planktonic cells. The combination of tigecycline and caspofungin exhibited maximum efficacy against mature biofilms, whereas combinations containing itraconazole exhibited minimal effects. Combinations of tigecycline with amphotericin B or anidulafungin were highly effective againstC. albicansbiofilm formation.DiscussionIn summary, tigecycline was highly active againstC. albicansparticularly when combined with amphotericin B and echinocandins.

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