posaconazole and Aspergillosis

Posaconazole is an orally bioavailable triazole antifungal agent for the treatment and prophylaxis of invasive fungal infection. We evaluated plasma posaconazole concentration data from juvenile (younger than 18 years; n = 12) and adult (18 to 64 years; n = 194) patients who participated in a multicenter, phase 3, open-label study that assessed the efficacy and safety of posaconazole treatment for persons who were intolerant of or had invasive fungal infection refractory to standard antifungal therapies. With the exception of one juvenile patient who received 400 mg/day as a divided dose on the day of sample collection, all patients received posaconazole at 800 mg/day as an oral suspension in divided doses. Plasma samples were analyzed through a validated liquid chromatographic-tandem mass spectrometric method with a lower limit of quantitation of 1 ng/ml. Because plasma posaconazole concentrations are relatively constant at steady state, the average of all plasma concentrations (C(av)) for each patient was calculated to provide a single steady-state plasma posaconazole concentration. A blinded data review committee reviewed all treatment outcomes. Variable posaconazole plasma concentrations were observed within both the juvenile and adult populations. Mean (median [range]) C(av) values for juvenile and adult patients were 776 ng/ml (579 ng/ml [85.3 to 2,891 ng/ml]) and 817 ng/ml (626 ng/ml [0 to 3,710 ng/ml]), respectively. Overall success rates and adverse event profiles were comparable. In conclusion, posaconazole concentrations in plasma were similar for juvenile and adult patients, suggesting that clinical outcomes are expected to be similar in adults and children with refractory invasive fungal infection.

Topics: Adolescent; Adult; Antifungal Agents; Aspergillosis; Body Surface Area; Body Weight; Child; Female; Humans; Male; Mycoses; Treatment Outcome; Triazoles

While the orally-active azoles such as fluconazole and posaconazole are effective antifungal agents, they potently inhibit a broad range of off-target human cytochrome P450 enzymes (CYPs) leading to various safety issues (e.g., drug-drug interactions, liver, and reproductive toxicities). Recently we described the rationally-designed, antifungal agent VT-1161 that is more selective for fungal CYP51 than related human CYP enzymes such as CYP3A4. Herein, we describe the use of a homology model of Aspergillus fumigatus to design and optimize a novel series of highly selective, broad spectrum fungal CYP51 inhibitors. This series includes the oral antifungal VT-1598 that exhibits excellent potency against yeast, dermatophyte, and mold fungal pathogens.

Topics: 14-alpha Demethylase Inhibitors; Antifungal Agents; Aspergillosis; Aspergillus fumigatus; Azoles; Cytochrome P450 Family 51; Drug Design; Fungi; Humans; Molecular Docking Simulation; Mycoses; Pyridines; Tetrazoles

The in vivo efficacy of posaconazole against 4 clinical Aspergillus fumigatus isolates with posaconazole MICs ranging from 0.03 to 16 mg/liter, as determined by CLSI method M38A, was assessed in a nonneutropenic murine model of disseminated aspergillosis. The underlying resistance mechanisms of the isolates included substitutions in the cyp51A gene at codon 220 (M220I), codon 54 (G54W), and codon 98 (L98H). The latter was combined with a 34-bp tandem repeat in the gene promoter region (TR L98H). The control isolate exhibited a wild-type phenotype without any known resistance mechanism. Oral posaconazole therapy was started 24 h after infection and was given once daily for 14 consecutive days. Mice were treated with four different doses (1 to 64 mg/kg of body weight), and survival was used as the end point. Survival was dependent both on the dose and on the MIC. The Hill equation with a variable slope fitted the relationship between the dose/MIC ratio and 14-day survival well (R2, 0.92), with a 50% effective dose (ED50) of 29.0 mg/kg (95% confidence interval [CI], 15.6 to 53.6 mg/kg). This also applied to the relationship between the area under the plasma concentration-time curve (AUC)/MIC ratio and 14-day survival (50% effective pharmacodynamic index [EI50], 321.3 [95% CI, 222.7 to 463.4]). Near-maximum survival was reached at an AUC/MIC ratio of nearly 1,000. These results indicate that treatment of infections with A. fumigatus strains for which MICs are 0.5 mg/liter requires doses exceeding the present licensed doses. Increasing the standard dosing regimen may have some effect and may be clinically useful if no alternatives are available.

Topics: Administration, Oral; Animals; Antifungal Agents; Area Under Curve; Aspergillosis; Aspergillus fumigatus; Cytochrome P-450 Enzyme System; Disease Models, Animal; Drug Administration Schedule; Female; Fungal Proteins; Mice; Microbial Sensitivity Tests; Mutation; Triazoles

This study presents in vitro susceptibility data for clinical (n = 48) and environmental (n = 31) isolates of Aspergillus terreus against nine antifungal agents. The methodology of the European Committee on Antimicrobial Susceptibility Testing was applied. Posaconazole and anidulafungin had the lowest and amphotericin B the highest MICs. No differences in susceptibility patterns were observed between environmental and clinical isolates.

Topics: Antifungal Agents; Aspergillosis; Aspergillus; DNA, Fungal; Humans; Microbial Sensitivity Tests; Soil Microbiology

Caspofungin is used for the treatment of acute invasive candidiasis and as salvage treatment for invasive aspergillosis. We report characteristics of isolates of Candida albicans and Aspergillus fumigatus detected in a patient with breakthrough infection complicating severe gastrointestinal surgery and evaluate the capability of susceptibility methods to identify candin resistance. The susceptibility of C. albicans to caspofungin and anidulafungin was investigated by Etest, microdilution (European Committee on Antibiotic Susceptibility Testing [EUCAST] and CLSI), disk diffusion, agar dilution, and FKS1 sequencing and in a mouse model. Tissue was examined by immunohistochemistry, PCR, and sequencing for the presence of A. fumigatus and resistance mutations. The MICs for the C. albicans isolate were as follows: >32 microg/ml caspofungin and 0.5 microg/ml anidulafungin by Etest, 2 microg/ml caspofungin and 0.125 microg/ml anidulafungin by EUCAST methods, and 1 microg/ml caspofungin and 0.5 microg/ml anidulafungin by CLSI methods. Sequencing of the FKS1 gene revealed a mutation leading to an S645P substitution. Caspofungin and anidulafungin failed to reduce kidney CFU counts in animals inoculated with this isolate (P > 0.05 compared to untreated control animals), while both candins completely sterilized the kidneys in animals infected with a control isolate. Disk diffusion and agar dilution methods clearly separated the two isolates. Immunohistochemistry and sequencing confirmed the presence of A. fumigatus without FSK1 resistance mutations in liver and lung tissues. Breakthrough disseminated aspergillosis and candidiasis developed despite an absence of characteristic FKS1 resistance mutations in the Aspergillus isolates. EUCAST and CLSI methodology did not separate the candin-resistant clinical isolate from the sensitive control isolate as well as did the Etest and agar methods.

Topics: Animals; Antifungal Agents; Aspergillosis; Aspergillus fumigatus; Candida albicans; Candidiasis; Caspofungin; Colony Count, Microbial; Echinocandins; Humans; Immunohistochemistry; Injections, Intraperitoneal; Lipopeptides; Mice; Mice, Inbred Strains; Microbial Sensitivity Tests; Polymerase Chain Reaction

Serum (1-->3)-beta-D-glucan concentrations were serially measured in the presence and absence of antifungal therapy in a murine model of invasive pulmonary aspergillosis. Serum (1-->3)-beta-D-glucan was detected early during the course of infection, and reductions in this biomarker were associated with improved survival in animals treated with antifungal agents.

Topics: Animals; Animals, Outbred Strains; Antifungal Agents; Aspergillosis; Aspergillus fumigatus; beta-Glucans; Biomarkers; Disease Models, Animal; Humans; Lung; Lung Diseases, Fungal; Mice; Mice, Inbred ICR; Proteoglycans; Treatment Outcome

Antifungal susceptibility testing of molds has been standardized in Europe and in the United States. Aspergillus fumigatus strains with resistance to azole drugs have recently been detected and the underlying molecular mechanisms of resistance characterized. Three hundred and ninety-three isolates, including 32 itraconazole-resistant strains, were used to define wild-type populations, epidemiological cutoffs, and cross-resistance between azole drugs. The epidemiological cutoff for itraconazole, voriconazole, and ravuconazole for the wild-type populations of A. fumigatus was < or =1 mg/liter. For posaconazole, the epidemiological cutoff was < or =0.25 mg/liter. Up till now, isolates susceptible to itraconazole have not yet displayed resistance to other azole drugs. Cross-resistance between azole drugs depends on specific mutations in cyp51A. Thus, a substitution of glycine in position 54 of Cyp51A confers cross-resistance between itraconazole and posaconazole. A substitution of methionine at position 220 or a duplication in tandem of a 34-bp fragment in the cyp51A promoter combined with a substitution of leucine at position 98 for histidine confers cross-resistance to all azole drugs tested. The results obtained in this study will help to develop clinical breakpoints for azole drugs and A. fumigatus.

Topics: Amino Acid Substitution; Antifungal Agents; Aspergillosis; Aspergillus fumigatus; Azoles; Cytochrome P-450 Enzyme System; Drug Resistance, Fungal; Fungal Proteins; Genes, Fungal; Humans; Itraconazole; Microbial Sensitivity Tests; Molecular Epidemiology; Molecular Sequence Data; Pyrimidines; Thiazoles; Triazoles; Voriconazole

Two clinical isolates of Aspergillus fumigatus, designated AT and DK, were recently obtained from patients failing caspofungin and itraconazole therapy, respectively. The isolates were tested by microdilution for susceptibility to itraconazole, voriconazole, posaconazole, ravuconazole, and caspofungin and by Etest for susceptibility to amphotericin B and caspofungin. Susceptibility testing documented that the DK isolate was azole resistant (itraconazole and posaconazole MICs, >4 microg/ml; voriconazole MIC, 2 microg/ml; ravuconazole MIC, 4 microg/ml), and the resistance was confirmed in a hematogenous mouse model, with mortality and the galactomannan index as the primary and secondary end points. Sequencing of the cyp51A gene revealed the M220K mutation, conferring multiazole resistance. The Etest, but not microdilution, suggested that the AT isolate was resistant to caspofungin (MIC, >32 microg/ml). In the animal model, this isolate showed reduced susceptibility to caspofungin. Sequencing of the FKS1 gene revealed no mutations; the enzyme retained full sensitivity in vitro; and investigation of the polysaccharide composition showed that the beta-(1,3)-glucan proportion was unchanged. However, gene expression profiling by Northern blotting and real-time PCR demonstrated that the FKS gene was expressed at a higher level in the AT isolate than in the susceptible control isolate. To our knowledge, this is the first report to document the presence of multiazole-resistant clinical isolates in Denmark and to demonstrate reduced susceptibility to caspofungin in a clinical A. fumigatus isolate with increased expression of the FKS gene. Further research to determine the prevalence of resistance in A. fumigatus worldwide, and to develop easier and reliable tools for the identification of such isolates in routine laboratories, is warranted.

Topics: Adult; Animals; Antifungal Agents; Aspergillosis; Aspergillus fumigatus; Azoles; Base Sequence; Caspofungin; Cytochrome P-450 Enzyme System; Disease Models, Animal; DNA, Fungal; Drug Resistance, Multiple, Fungal; Echinocandins; Fungal Proteins; Genes, Fungal; Glucosyltransferases; Humans; In Vitro Techniques; Itraconazole; Lipopeptides; Mice; Microbial Sensitivity Tests; Mutation

Aspergillus fumigatus is a leading cause of death in immunocompromised patients and a frequent colonizer of the respiratory tracts of asthma and cystic fibrosis (CF) patients. Biofilms enable bacteria and yeasts to persist in infections and can contribute to antimicrobial resistance. We investigated the ability of A. fumigatus to form biofilms on polystyrene (PS) and human bronchial epithelial (HBE) and CF bronchial epithelial (CFBE) cells. We developed a novel in vitro coculture model of A. fumigatus biofilm formation on HBE and CFBE cells. Biofilm formation was documented by dry weight, scanning electron microscopy (SEM), and confocal scanning laser microscopy (CSLM). The in vitro antifungal activities of seven antifungal drugs were tested by comparing planktonic and sessile A. fumigatus strains. A. fumigatus formed an extracellular matrix on PS and HBE and CFBE cells as evidenced by increased dry weight, SEM, and CSLM. These biofilms exhibited decreased antifungal drug susceptibility and were adherent to the epithelial cells, with fungi remaining viable throughout 3 days. These observations might have implications for treatment of A. fumigatus colonization in chronic lung diseases and for its potential impact on airway inflammation, damage, and infection.

Topics: Antifungal Agents; Aspergillosis; Aspergillus fumigatus; Biofilms; Bronchi; Cells, Cultured; Cystic Fibrosis; Drug Resistance, Fungal; Epithelial Cells; Humans; Microbial Sensitivity Tests; Microscopy, Confocal; Microscopy, Electron, Scanning; Respiratory Tract Infections

The MICs and fractional inhibitory concentrations of posaconazole (POS) and voriconazole (VRZ), alone and in combination with amphotericin B (AMB), for the conidia and hyphae of 100 Aspergillus isolates were evaluated. POS-AMB had more synergistic activity against hyphae (75% of isolates) than VRZ-AMB (37%) and significantly more synergistic activity against hyphae than against conidia (12%).

Topics: Amphotericin B; Antifungal Agents; Aspergillosis; Aspergillus; Drug Synergism; Drug Therapy, Combination; Microbial Sensitivity Tests; Pyrimidines; Triazoles; Voriconazole

As part of a detailed study, the syntheses, biological activities, and pharmacokinetic properties of hydroxylated analogues of the previously described broad spectrum antifungal agents, Sch 51048 (1), Sch 50001 (3), and Sch 50002 (4), are described. Based on an overall superior profile, one of the alcohols, Sch 56592 (2), was selected for clinical studies.

Topics: Alcohols; Animals; Antifungal Agents; Aspergillosis; Candidiasis; Chemistry, Pharmaceutical; Dose-Response Relationship, Drug; Drug Design; Drug Evaluation, Preclinical; Haplorhini; Humans; Immunosuppressive Agents; Mice; Models, Chemical; Time Factors; Triazoles