scholarly journals Pharmacodynamics of Itraconazole against Aspergillus fumigatus in anIn VitroModel of the Human Alveolus: Perspectives on the Treatment of Triazole-Resistant Infection and Utility of Airway Administration

2012 ◽  
Vol 56 (8) ◽  
pp. 4146-4153 ◽  
Author(s):  
Zaid Al-Nakeeb ◽  
Ajay Sudan ◽  
Adam R. Jeans ◽  
Lea Gregson ◽  
Joanne Goodwin ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Therapeutic Strategies ◽  
Wild Type ◽  
Content Type ◽  
Exposure Response ◽  
Prevention And Treatment ◽  
Resistant Infection ◽  
Resistant Strains ◽  
Type Strains

ABSTRACTItraconazole is used for the prevention and treatment of infections caused byAspergillus fumigatus. An understanding of the pharmacodynamics of itraconazole against wild-type and triazole-resistant strains provides a basis for innovative therapeutic strategies for treatment of infections. Anin vitromodel of the human alveolus was used to define the pharmacodynamics of itraconazole. Galactomannan was used as a biomarker. The effect of systemic and airway administration of itraconazole was assessed, as was a combination of itraconazole administered to the airway and systemically administered 5FC. Systemically administered itraconazole against the wild type induced a concentration-dependent decline in galactomannan in the alveolar and endothelial compartments. No exposure-response relationships were apparent for the L98H, M220T, or G138C mutant. The administration of itraconazole to the airway resulted in comparable exposure-response relationships to those observed with systemic therapy. This was achieved without detectable concentrations of drug within the endothelial compartment. The airway administration of itraconazole resulted in a definite but submaximal effect in the endothelial compartment against the L98H mutant. The administration of 5FC resulted in a concentration-dependent decline in galactomannan in both the alveolar and endothelial compartments. The combination of airway administration of itraconazole and systemically administered 5FC was additive. Systemic administration of itraconazole is ineffective against Cyp51 mutants. The airway administration of itraconazole is effective for the treatment of wild-type strains and appears to have some activity against the L98H mutants. Combination with other agents, such as 5FC, may enable the attainment of near-maximal antifungal activity.

scholarly journals In VitroActivity of Ceftazidime-Avibactam Combination inIn VitroCheckerboard Assays

2014 ◽  
Vol 59 (2) ◽  
pp. 1138-1144 ◽  
Author(s):  
Johanna Berkhout ◽  
Maria J. Melchers ◽  
Anita C. van Mil ◽  
Wright W. Nichols ◽  
Johan W. Mouton
Keyword(s):  
Antibacterial Activity ◽  
Enterobacter Cloacae ◽  
Resistance Mechanisms ◽  
Maximum Effect ◽  
Wild Type ◽  
Dependent Effect ◽  
Content Type ◽  
Resistant Strains ◽  
Type Strains

ABSTRACTTo evaluate thein vitroeffects of the combination of ceftazidime and avibactam on the MICs of both compounds, checkerboard assays were performed for 81 clinical strains, including 55Enterobacteriaceaestrains (32Klebsiella pneumoniae, 19Escherichia coli, 1Citrobacter freundii, and 3Enterobacter cloacae) and 26 strains ofPseudomonas aeruginosa, all with known resistance mechanisms such as extended-spectrum β-lactamases (ESBLs) and carbapenemases, phenotypically or molecularly determined. Phenotypically ceftazidime-resistant strains (n= 69) were analyzed in more detail. For theEnterobacteriaceaestrains, a concentration-dependent effect of avibactam was found for most strains with a maximum effect of avibactam at a concentration of 4 mg/liter, which decreased all ceftazidime MICs to ≤4 mg/liter. Avibactam alone also showed antibacterial activity (the MIC50and MIC90being 8 and 16 mg/liter, respectively). For the ceftazidime-resistantP. aeruginosastrains, considerable inhibition of β-lactamases by avibactam was acquired at a concentration of 4 mg/liter, which decreased all ceftazidime MICs except one to ≤8 mg/liter (the CLSI and EUCAST susceptible breakpoint). Increasing the concentration of avibactam further decreased the MICs, resulting in a maximum effect for most strains at 8 to 16 mg/liter. In summary, for most strains, the tested addition of avibactam of 4 mg/liter restored the antibacterial activity of ceftazidime to a level comparable to that of wild-type strains, indicating full inhibition, and strains became susceptible according to the EUCAST and CLSI criteria. Based on thesein vitrodata, avibactam is a promising inhibitor of different β-lactamases, including ESBLs and carbapenemases.

scholarly journals SEARCH FOR NEW ANTILEISHMANIAL CHEMOTHERAPEUTICS

2018 ◽  
Vol 10 (1) ◽  
pp. 46
Author(s):  
Nabanita Kar ◽  
Santanu Ghosh ◽  
Leena Kumari ◽  
Shreyasi Chakraborty ◽  
Tanmoy Bera
Keyword(s):  
Betulinic Acid ◽  
Leishmania Donovani ◽  
Antileishmanial Activity ◽  
Gas Chromatography Mass Spectrometry ◽  
Drug Resistant ◽  
Wild Type ◽  
Leaf Oil ◽  
Resistant Strains ◽  
Type Strains

Objective: The objective of this work was to screen a number of compounds for their antileishmanial efficacy and cytotoxicity profiling.Methods: Curry leaf oil, cypress oil and spikenard oil were identified by gas chromatography-mass spectrometry (GC/MS) analysis. Betulinic acid, spikenard oil, cypress oil and curry leaf oil were evaluated for their in vitro antileishmanial activity against Leishmania donovani AG83 wild-type, sodium stibogluconate resistant (SSG-resistant), paromomycin (PMM-resistant) and GE1 field type strains on axenic and cellular amastigote model and compared the results with standard drugs used to treat leishmaniasis.Results: Betulinic acid showed strong antileishmanial activity against wild-type (SI= 192.8), SSG-resistant (SI= 19.3) and GE1 strains (SI= 100), whereas cypress oil has produced highest antileishmanial activity against PMM-resistant strains (SI= 15.09) among all the tested drugs. The data obtained also revealed that cypress oil had the maximum CC50 value of 452.9 μl among all standard and tested drugs.Conclusion: All tested drugs had antileishmanial property but among them, betulinic acid possess strong antileishmanial activity in case of both wild-type and drug-resistant leishmaniasis.

scholarly journals Genetic Barcodes for Improved Environmental Tracking of an Anthrax Simulant

2012 ◽  
Vol 78 (23) ◽  
pp. 8272-8280 ◽  
Author(s):  
Patricia Buckley ◽  
Bryan Rivers ◽  
Sarah Katoski ◽  
Michael H. Kim ◽  
F. Joseph Kragl ◽  
...  
Keyword(s):  
Environmental Fate ◽  
Wild Type ◽  
Risk Models ◽  
Content Type ◽  
Genetic Signatures ◽  
Isogenic Strains ◽  
Type Strains ◽  
Long Term Studies

ABSTRACTThe development of realistic risk models that predict the dissemination, dispersion and persistence of potential biothreat agents have utilized nonpathogenic surrogate organisms such asBacillus atrophaeussubsp.globigiior commercial products such asBacillus thuringiensissubsp.kurstaki. Comparison of results from outdoor tests under different conditions requires the use of genetically identical strains; however, the requirement for isogenic strains limits the ability to compare other desirable properties, such as the behavior in the environment of the same strain prepared using different methods. Finally, current methods do not allow long-term studies of persistence or reaerosolization in test sites where simulants are heavily used or in areas whereB. thuringiensissubsp.kurstakiis applied as a biopesticide. To create a set of genetically heterogeneous yet phenotypically indistinguishable strains so that variables intrinsic to simulations (e.g., sample preparation) can be varied and the strains can be tested under otherwise identical conditions, we have developed a strategy of introducing small genetic signatures (“barcodes”) into neutral regions of the genome. The barcodes are stable over 300 generations and do not impactin vitrogrowth or sporulation. Each barcode contains common and specific tags that allow differentiation of marked strains from wild-type strains and from each other. Each tag is paired with specific real-time PCR assays that facilitate discrimination of barcoded strains from wild-type strains and from each other. These uniquely barcoded strains will be valuable tools for research into the environmental fate of released organisms by providing specific artificial detection signatures.

scholarly journals The Small GTPase RacA Mediates Intracellular Reactive Oxygen Species Production, Polarized Growth, and Virulence in the Human Fungal Pathogen Aspergillus fumigatus

2010 ◽  
Vol 10 (2) ◽  
pp. 174-186 ◽  
Author(s):  
Haiyan Li ◽  
Bridget M. Barker ◽  
Nora Grahl ◽  
Srisombat Puttikamonkul ◽  
Jeremey D. Bell ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Aspergillus Fumigatus ◽  
Invasive Pulmonary Aspergillosis ◽  
Reactive Oxygen ◽  
Small Gtpase ◽  
Oxygen Species ◽  
Wild Type ◽  
Content Type ◽  
Diphenylene Iodonium

ABSTRACTAspergillus fumigatusis the predominant mold pathogen in immunocompromised patients. In this study, we present the first characterization of the small GTPase RacA inA. fumigatus. To gain insight into the function ofracAin the growth and pathogenesis ofA. fumigatus, we constructed a strain that lacks a functionalracAgene. The ΔracAstrain showed significant morphological defects, including a reduced growth rate and abnormal conidiogenesis on glucose minimal medium. In the ΔracAstrain, apical dominance in the leading hyphae is lost and, instead, multiple axes of polarity emerge. Intriguingly, superoxide production at the hyphal tips was reduced by 25% in the ΔracAstrain. Treatment of wild-type hyphae with diphenylene iodonium, an inhibitor of NADPH oxidase, resulted in phenotypes similar to that of the ΔracAstrain. These data suggest that ΔracAstrain phenotypes may be due to a reduction or alteration in the production of reactive oxygen species. Most surprisingly, despite these developmental and growth abnormalities, the ΔracAstrain retained at least wild-type virulence in both an insect model and two immunologically distinct murine models of invasive pulmonary aspergillosis. These results demonstrate thatin vitrogrowth phenotypes do not always correlate within vivovirulence and raise intriguing questions about the role of RacA inAspergillusvirulence.

scholarly journals Activity of a Novel 1,3-Beta-D-Glucan Synthase Inhibitor, Ibrexafungerp (Formerly SCY-078), against Candida glabrata

2019 ◽  
Vol 63 (12) ◽  
Author(s):  
M. Ghannoum ◽  
L. Long ◽  
N. Isham ◽  
C. Hager ◽  
R. Wilson ◽  
...  
Keyword(s):  
Candida Glabrata ◽  
Wild Type ◽  
Glucan Synthase ◽  
Content Type ◽  
Clinical Strains ◽  
Resistant Strains ◽  
Oral Availability ◽  
Synthase Inhibitor ◽  
Time Kill ◽  
Type Strains

ABSTRACT Ibrexafungerp (formerly SCY-078), a novel glucan synthase inhibitor with oral availability, was evaluated for activity against Candida glabrata. The susceptibility of clinical strains to ibrexafungerp was determined by microdilution and time-kill assays. The MIC range against wild-type strains was 1 to 2 μg/ml. Ibrexafungerp was also active against the majority of echinocandin-resistant strains. Time-kill studies showed 4- to 6-log-unit reductions in growth at 24 and 48 h with concentrations of 0.25 to 4 μg/ml.

scholarly journals In VitroBiochemical Study of CYP51-Mediated Azole Resistance in Aspergillus fumigatus

2015 ◽  
Vol 59 (12) ◽  
pp. 7771-7778 ◽  
Author(s):  
Andrew G. S. Warrilow ◽  
Josie E. Parker ◽  
Claire L. Price ◽  
W. David Nes ◽  
Steven L. Kelly ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Inhibitory Concentration ◽  
Point Mutations ◽  
Residual Activity ◽  
Azole Resistance ◽  
Wild Type ◽  
Biochemical Basis ◽  
Content Type ◽  
Resistant Phenotype

ABSTRACTThe incidence of triazole-resistantAspergillusinfections is increasing worldwide, often mediated through mutations in the CYP51A amino acid sequence. New classes of azole-based drugs are required to combat the increasing resistance to existing triazole therapeutics. In this study, a CYP51 reconstitution assay is described consisting of eburicol, purified recombinantAspergillus fumigatusCPR1 (AfCPR1), andEscherichia colimembrane suspensions containing recombinantA. fumigatusCYP51 proteins, allowingin vitroscreening of azole antifungals. Azole-CYP51 studies determining the 50% inhibitory concentration (IC50) showed thatA. fumigatusCYP51B (Af51B IC50, 0.50 μM) was 34-fold more susceptible to inhibition by fluconazole thanA. fumigatusCYP51A (Af51A IC50, 17 μM) and that Af51A and Af51B were equally susceptible to inhibition by voriconazole, itraconazole, and posaconazole (IC50s of 0.16 to 0.38 μM). Af51A-G54W and Af51A-M220K enzymes were 11- and 15-fold less susceptible to inhibition by itraconazole and 30- and 8-fold less susceptible to inhibition by posaconazole than wild-type Af51A, confirming the azole-resistant phenotype of these two Af51A mutations. Susceptibility to voriconazole of Af51A-G54W and Af51A-M220K was only marginally lower than that of wild-type Af51A. Susceptibility of Af51A-L98H to inhibition by voriconazole, itraconazole, and posaconazole was only marginally lower (less than 2-fold) than that of wild-type Af51A. However, Af51A-L98H retained 5 to 8% residual activity in the presence of 32 μM triazole, which could confer azole resistance inA. fumigatusstrains that harbor the Af51A-L98H mutation. The AfCPR1/Af51 assay system demonstrated the biochemical basis for the increased azole resistance ofA. fumigatusstrains harboring G54W, L98H, and M220K Af51A point mutations.

scholarly journals The Strength of Synergistic Interaction between Posaconazole and Caspofungin Depends on the Underlying Azole Resistance Mechanism of Aspergillus fumigatus

2015 ◽  
Vol 59 (3) ◽  
pp. 1738-1744 ◽  
Author(s):  
Eleftheria Mavridou ◽  
Joseph Meletiadis ◽  
Antony Rijs ◽  
Johan W. Mouton ◽  
Paul E. Verweij
Keyword(s):  
Aspergillus Fumigatus ◽  
Resistance Mechanism ◽  
Fungal Growth ◽  
Resistance Mechanisms ◽  
Azole Resistance ◽  
Wild Type ◽  
Content Type ◽  
Synergistic Interactions ◽  
Drug Concentrations

ABSTRACTThe majority of azole resistance mechanisms inAspergillus fumigatuscorrespond to mutations in thecyp51Agene. As azoles are less effective against infections caused by multiply azole-resistantA. fumigatusisolates, new therapeutic options are warranted for treating these infections. We therefore investigated thein vitrocombination of posaconazole (POSA) and caspofungin (CAS) against 20 wild-type and resistantA. fumigatusisolates with 10 different resistance mechanisms. Fungal growth was assessed with the XTT [2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide inner salt] method. Pharmacodynamic interactions were assessed with the fractional inhibitory concentration (FIC) index (FICi) on the basis of 10% (FICi-0), 25% (FICi-1), or 53 0% (FICi-2) growth, and FICs were correlated with POSA and CAS concentrations. Synergy and antagonism were concluded when the FICi values were statistically significantly (ttest,P< 0.05) lower than 1 and higher than 1.25, respectively. Significant synergy was found for all isolates with mean FICi-0 values ranging from 0.28 to 0.75 (median, 0.46). Stronger synergistic interactions were found with FICi-1 (median, 0.18; range, 0.07 to 0.47) and FICi-2 (0.31; 0.07 to 0.6). The FICi-2 values of isolates with tandem-repeat-containing mutations or codon M220 were lower than those seen with the other isolates (P< 0.01). FIC-2 values were inversely correlated with POSA MICs (rs= −0.52,P= 0.0006) and linearly with the ratio of drug concentrations in combination over the MIC of POSA (rs= 0.76,P< 0.0001) and CAS (rs= 0.52,P= 0.0004). The synergistic effect of the combination of POSA and CAS (POSA/CAS) againstA. fumigatusisolates depended on the underlying azole resistance mechanism. Moreover, the drug combination synergy was found to be increased against isolates with elevated POSA MICs compared to wild-type isolates.

scholarly journals Validation of a New Aspergillus Real-Time PCR Assay for Direct Detection of Aspergillus and Azole Resistance of Aspergillus fumigatus on Bronchoalveolar Lavage Fluid

2015 ◽  
Vol 53 (3) ◽  
pp. 868-874 ◽  
Author(s):  
Ga-Lai M. Chong ◽  
Wendy W. J. van de Sande ◽  
Gijs J. H. Dingemans ◽  
Giel R. Gaajetaan ◽  
Alieke G. Vonk ◽  
...  
Keyword(s):  
Bronchoalveolar Lavage ◽  
Aspergillus Fumigatus ◽  
Real Time ◽  
Real Time Pcr ◽  
Gold Standard ◽  
Azole Resistance ◽  
Wild Type ◽  
Pcr Assay ◽  
Content Type ◽  
Resistant Strains

Azole resistance inAspergillus fumigatusis increasingly reported. Here, we describe the validation of the AsperGenius, a new multiplex real-time PCR assay consisting of two multiplex real-time PCRs, one that identifies the clinically relevantAspergillusspecies, and one that detects the TR34, L98H, T289A, and Y121F mutations in CYP51A and differentiates susceptible from resistantA. fumigatusstrains. The diagnostic performance of the AsperGenius assay was tested on 37 bronchoalveolar lavage (BAL) fluid samples from hematology patients and 40 BAL fluid samples from intensive care unit (ICU) patients using a BAL fluid galactomannan level of ≥1.0 or positive culture as the gold standard for detecting the presence ofAspergillus. In the hematology and ICU groups combined, there were 22 BAL fluid samples from patients with invasive aspergillosis (IA) (2 proven, 9 probable, and 11 nonclassifiable). Nineteen of the 22 BAL fluid samples were positive, according to the gold standard. The optimal cycle threshold value for the presence ofAspergilluswas <36. Sixteen of the 19 BAL fluid samples had a positive PCR (2Aspergillusspecies and 14A. fumigatussamples). This resulted in a sensitivity, specificity, and positive and negative predictive values of 88.9%, 89.3%, 72.7%, and 96.2%, respectively, for the hematology group and 80.0%, 93.3%, 80.0%, and 93.3%, respectively, in the ICU group. The CYP51A real-time PCR confirmed 12 wild-type and 2 resistant strains (1 TR34-L98H and 1 TR46-Y121F-T289A mutant). Voriconazole therapy failed for both patients. The AsperGenius multiplex real-time PCR assay allows for sensitive and fast detection ofAspergillusspecies directly from BAL fluid samples. More importantly, this assay detects and differentiates wild-type from resistant strains, even if BAL fluid cultures remain negative.

scholarly journals Fitness Studies of Azole-Resistant Strains of Aspergillus fumigatus

2015 ◽  
Vol 59 (12) ◽  
pp. 7866-7869 ◽  
Author(s):  
Isabel Valsecchi ◽  
Emilia Mellado ◽  
Rémi Beau ◽  
Shriya Raj ◽  
Jean-Paul Latgé
Keyword(s):  
Aspergillus Fumigatus ◽  
Parental Strain ◽  
Fitness Cost ◽  
Content Type ◽  
Strain Competition ◽  
Resistant Strains

ABSTRACTIsogenic bar-coded strains ofAspergillus fumigatuscarrying the G54W or M220K mutation in Cyp51A were constructed.In vitro, the growth and conidiation capacities of the mutants were similar to those of the parental strain. Competition studies in the absence of azoles showed that there was no adverse fitness cost for the azole-resistantA. fumigatusstrainsin vitroorin vivocompared to the parental strain.

scholarly journals Elevated MIC Values of Imidazole Drugs against Aspergillus fumigatus Isolates with TR 34 /L98H/S297T/F495I Mutation

2018 ◽  
Vol 62 (5) ◽  
Author(s):  
Yong Chen ◽  
Zongwei Li ◽  
Xuelin Han ◽  
Shuguang Tian ◽  
Jingya Zhao ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Susceptibility Testing ◽  
Antifungal Susceptibility ◽  
Azole Resistance ◽  
Pyrenophora Teres ◽  
Str Typing ◽  
Content Type ◽  
Resistant Strains ◽  
Short Tandem

ABSTRACT The use of azole fungicides in agriculture is believed to be one of the main reasons for the emergence of azole resistance in Aspergillus fumigatus . Though widely used in agriculture, imidazole fungicides have not been linked to resistance in A. fumigatus . This study showed that elevated MIC values of imidazole drugs were observed against A. fumigatus isolates with TR 34 /L98H/S297T/F495I mutation, but not among isolates with TR 34 /L98H mutation. Short-tandem-repeat (STR) typing analysis of 580 A. fumigatus isolates from 20 countries suggested that the majority of TR 34 /L98H/S297T/F495I strains from China were genetically different from the predominant major clade comprising most of the azole-resistant strains and the strains with the same mutation from the Netherlands and Denmark. Alignments of sterol 14α-demethylase sequences suggested that F495I in A. fumigatus was orthologous to F506I in Penicillium digitatum and F489L in Pyrenophora teres , which have been reported to be associated with imidazole resistance. In vitro antifungal susceptibility testing of different recombinants with cyp51A mutations further confirmed the association of the F495I mutation with imidazole resistance. In conclusion, this study suggested that environmental use of imidazole fungicides might confer selection pressure for the emergence of azole resistance in A. fumigatus .

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