scholarly journals In VitroInteraction between Alginate Lyase and Amphotericin B against Aspergillus fumigatus Biofilm Determined by Different Methods

2012 ◽  
Vol 57 (3) ◽  
pp. 1275-1282 ◽  
Author(s):  
Francesca Bugli ◽  
Brunella Posteraro ◽  
Massimiliano Papi ◽  
Riccardo Torelli ◽  
Alessandro Maiorana ◽  
...  
Keyword(s):  
Invasive Aspergillosis ◽  
Aspergillus Fumigatus ◽  
Amphotericin B ◽  
Extracellular Polymeric Substances ◽  
Alginate Lyase ◽  
Antifungal Drugs ◽  
Antibiofilm Activity ◽  
Content Type ◽  
Time Kill

ABSTRACTAspergillus fumigatusbiofilms represent a problematic clinical entity, especially because of their recalcitrance to antifungal drugs, which poses a number of therapeutic implications for invasive aspergillosis, the most difficult-to-treatAspergillus-related disease. While the antibiofilm activities of amphotericin B (AMB) deoxycholate and its lipid formulations (e.g., liposomal AMB [LAMB]) are well documented, the effectiveness of these drugs in combination with nonantifungal agents is poorly understood. In the present study,in vitrointeractions between polyene antifungals (AMB and LAMB) and alginate lyase (AlgL), an enzyme degrading the polysaccharides produced as extracellular polymeric substances (EPSs) within the biofilm matrix, againstA. fumigatusbiofilms were evaluated by using the checkerboard microdilution and the time-kill assays. Furthermore, atomic force microscopy (AFM) was used to image and quantify the effects of AlgL-antifungal combinations on biofilm-growing hyphal cells. On the basis of fractional inhibitory concentration index values, synergy was found between both AMB formulations and AlgL, and this finding was also confirmed by the time-kill test. Finally, AFM analysis showed that whenA. fumigatusbiofilms were treated with AlgL or polyene alone, as well as with their combination, both a reduction of hyphal thicknesses and an increase of adhesive forces were observed compared to the findings for untreated controls, probably owing to the different action by the enzyme or the antifungal compounds. Interestingly, marked physical changes were noticed inA. fumigatusbiofilms exposed to the AlgL-antifungal combinations compared with the physical characteristics detected after exposure to the antifungals alone, indicating that AlgL may enhance the antibiofilm activity of both AMB and LAMB, perhaps by disrupting the hypha-embedding EPSs and thus facilitating the drugs to reach biofilm cells. Taken together, our results suggest that a combination of AlgL and a polyene antifungal may prove to be a new therapeutic strategy for invasive aspergillosis, while reinforcing the EPS as a valuable antibiofilm drug target.

scholarly journals In VitroInteractions between Aspirin and Amphotericin B against Planktonic Cells and Biofilm Cells of Candida albicans and C. parapsilosis

2012 ◽  
Vol 56 (6) ◽  
pp. 3250-3260 ◽  
Author(s):  
Yabin Zhou ◽  
Ganggang Wang ◽  
Yutang Li ◽  
Yang Liu ◽  
Yu Song ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Amphotericin B ◽  
Antimicrobial Agents ◽  
Positive Interactions ◽  
Antibiofilm Activity ◽  
Data Generation ◽  
Planktonic Cells ◽  
Content Type ◽  
Time Kill

ABSTRACTThe increase in drug resistance and invasion caused by biofilm formation brings enormous challenges to the management ofCandidainfection. Aspirin's antibiofilm activityin vitrowas discovered recently. The spectrophotometric method and the XTT {2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide} reduction assay used for data generation make it possible to evaluate fungal biofilm growth accurately. The combined use of the most commonly used methods, the fractional inhibitory concentration index (FICI) and a newly developed method, the ΔEmodel, which uses the concentration-effect relationship over the whole concentration range instead of using the MIC index alone, makes the interpretation of results more reliable. As an attractive tool for studying the pharmacodynamics of antimicrobial agents, time-kill curves can provide detailed information about antimicrobial efficacy as a function of both time and concentration. In the present study,in vitrointeractions between aspirin (acetylsalicylic acid [ASA]) and amphotericin B (AMB) against planktonic cells and biofilm cells ofCandida albicansandC. parapsilosiswere evaluated by the checkerboard microdilution method and the time-kill test. Synergistic and indifferent effects were found for the combination of ASA and AMB against planktonic cells, while strong synergy was found against biofilm cells analyzed by FICI. The ΔEmodel gave more consistent results with FICI. The positive interactions in concentration were also confirmed by the time-kill test. Moreover, this approach also revealed the pharmacodynamics changes of ASA and synergistic action on time. Our findings suggest a potential clinical use for combination therapy with ASA and AMB to augment activity against biofilm-associated infections.

scholarly journals Dectin-2-Targeted Antifungal Liposomes Exhibit Enhanced Efficacy

mSphere ◽  
2019 ◽  
Vol 4 (5) ◽  
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.

scholarly journals In VitroActivities of Nine Antifungal Drugs against 81 Phialophora and Cyphellophora Isolates

2012 ◽  
Vol 56 (11) ◽  
pp. 6044-6047 ◽  
Author(s):  
Peiying Feng ◽  
M. Javad Najafzadeh ◽  
Jiufeng Sun ◽  
Sarah Ahmed ◽  
Liyan Xi ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Antifungal Drugs ◽  
Content Type

ABSTRACTCyphellophora guyanensis(n= 15), otherCyphellophoraspecies (n= 11),Phialophora europaea(n= 43), and otherPhialophoraspecies (n= 12) were testedin vitroagainst nine antifungal drugs. The MIC90s across all of the strains (n= 81) were, in increasing order, as follows: posaconazole, 0.063 μg/ml; itraconazole, 0.5 μg/ml; voriconazole, 1 μg/ml; micafungin, 1 μg/ml; terbinafine, 2 μg/ml; isavuconazole, 4 μg/ml; caspofungin, 4 μg/ml; fluconazole, 8 μg/ml; amphotericin B, 16 μg/ml.

scholarly journals In Vivo Efficacy of Liposomal Amphotericin B against Wild-Type and Azole-Resistant Aspergillus fumigatus Isolates in Two Different Immunosuppression Models of Invasive Aspergillosis

2017 ◽  
Vol 61 (6) ◽  
Author(s):  
Seyedmojtaba Seyedmousavi ◽  
Johan W. Mouton ◽  
Willem J. G. Melchers ◽  
Paul E. Verweij
Keyword(s):  
Invasive Aspergillosis ◽  
Aspergillus Fumigatus ◽  
Amphotericin B ◽  
Liposomal Amphotericin ◽  
Treated Group ◽  
Liposomal Amphotericin B ◽  
Wild Type ◽  
Resistance Mutations ◽  
Content Type

ABSTRACT Using an immunocompetent murine model of invasive aspergillosis (IA), we previously reported that the efficacy of liposomal amphotericin B (L-AmB) (Ambisome) is not hampered by the presence of azole resistance mutations in Aspergillus fumigatus (S. Seyedmousavi, W. J. G. Melchers, J. W. Mouton, and P. E. Verweij, Antimicrob Agents Chemother 57:1866–1871, 2013, https://doi.org/10.1128/AAC.02226-12 ). We here investigated the role of immune suppression, i.e., neutropenia and steroid treatment, in L-AmB efficacy in mice infected with wild-type (WT) A. fumigatus and with azole-resistant A. fumigatus harboring a TR34/L98H mutation in the cyp-51A gene. Survival of treated animals at day 14 in both immunosuppressed models was significantly better than that of nontreated controls. A dose-response relationship was observed that was independent of the azole-resistant mechanism and the immunosuppression method used. In the neutropenic model, 100% survival was reached at an L-AmB dose of 16 mg/kg of body weight for the WT strain and the TR34/L98H isolate. In the steroid-treated group, 90.9% survival and 100% survival were achieved for the WT isolate and the TR34/L98H isolate with an L-AmB dose of 16 mg/kg, respectively. The 50% effective dose (ED50) was 1.40 mg/kg (95% confidence interval [CI], 0.66 to 3.00 mg/kg) for the WT isolate and 1.92 mg/kg (95% CI, 0.60 to 6.17 mg/kg) for the TR34/L98H isolate in the neutropenic model and was 2.40 mg/kg (95% CI, 1.93 to 2.97 mg/kg) for the WT isolate and 2.56 mg/kg (95% CI, 1.43 to 4.56 mg/kg) for the TR34/L98H isolate in the steroid-treated group. Overall, there were no significant differences between the two different immunosuppressed conditions in the efficacy of L-AmB against the wild-type and azole-resistant isolates (P > 0.9). However, the required L-AmB exposure was significantly higher than that seen in the immunocompetent model.

scholarly journals In VitroActivities of a Wide Panel of Antifungal Drugs against Various Scopulariopsis and Microascus Species

2015 ◽  
Vol 59 (9) ◽  
pp. 5827-5829 ◽  
Author(s):  
Magdalena Skóra ◽  
Małgorzata Bulanda ◽  
Tomasz Jagielski
Keyword(s):  
Amphotericin B ◽  
Effective Concentration ◽  
Antifungal Drugs ◽  
Antifungal Effect ◽  
Content Type ◽  
Minimal Effective Concentration

ABSTRACTThein vitroactivities of 11 antifungal drugs against 68ScopulariopsisandMicroascusstrains were investigated. Amphotericin B, 5-fluorocytosine, fluconazole, itraconazole, ketoconazole, miconazole, posaconazole, voriconazole, and ciclopirox showed no or poor antifungal effect. The best activities were exhibited by terbinafine and caspofungin, where the MIC and MEC (minimal effective concentration) ranges were 0.0313 to >16 μg/ml and 0.125 to 16 μg/ml, respectively. The MIC and MEC modes were both 1 µg/ml for terbinafine and caspofungin; the MIC50and MEC50were 1 µg/ml for both drugs, whereas the MIC90and MEC90were 4 µg/ml and 16 µg/ml, respectively.

scholarly journals In VitroCombination of Isavuconazole with Micafungin or Amphotericin B Deoxycholate against Medically Important Molds

2014 ◽  
Vol 58 (11) ◽  
pp. 6934-6937 ◽  
Author(s):  
Aspasia Katragkou ◽  
Matthew McCarthy ◽  
Joseph Meletiadis ◽  
Vidmantas Petraitis ◽  
Patriss W. Moradi ◽  
...  
Keyword(s):  
Combination Therapy ◽  
Invasive Aspergillosis ◽  
Amphotericin B ◽  
Aspergillus Flavus ◽  
Aspergillus Terreus ◽  
Synergistic Activity ◽  
Content Type ◽  
Amphotericin B Deoxycholate ◽  
Combination Studies

ABSTRACTWhether isavuconazole, an extended-spectrum triazole, possesses synergistic activity in combination therapy with echinocandins or amphotericin B for the treatment of invasive molds infections has not been studied. Ourin vitrocombination studies showed that isavuconazole and micafungin are synergistically active againstAspergillus fumigatus,Aspergillus flavus,Aspergillus terreus, andCunninghamella bertholletiae. These results suggest that isavuconazole, in combination with micafungin, may have a role in the treatment of invasive aspergillosis and warrants further investigation.

scholarly journals Molecular Studies Reveal Frequent Misidentification of Aspergillus fumigatus by Morphotyping

2006 ◽  
Vol 5 (10) ◽  
pp. 1705-1712 ◽  
Author(s):  
S. Arunmozhi Balajee ◽  
David Nickle ◽  
Janos Varga ◽  
Kieren A. Marr
Keyword(s):  
Aspergillus Fumigatus ◽  
Amphotericin B ◽  
Distinct Species ◽  
Enzyme Polymorphism ◽  
Antifungal Drugs ◽  
Clinical Isolates ◽  
Polymorphism Analysis ◽  
In Vitro Susceptibility ◽  
Epidemiological Surveys

ABSTRACT Aspergillus fumigatus has been understood to be the most common cause of invasive aspergillosis (IA) in all epidemiological surveys. However, recent studies have uncovered a large degree of genetic heterogeneity between isolates morphologically identified as A. fumigatus, leading to the description of a new species, Aspergillus lentulus. Here, we examined the genetic diversity of clinical isolates identified as A. fumigatus using restriction enzyme polymorphism analysis and sequence-based identification. Analysis of 50 clinical isolates from geographically diverse locations recorded the presence of at least three distinct species: A. lentulus, Aspergillus udagawae, and A. fumigatus. In vitro, A. lentulus isolates demonstrated decreased susceptibility to antifungal drugs currently used for IA, including amphotericin B, voriconazole, and caspofungin; A. udagawae isolates demonstrated decreased in vitro susceptibility to amphotericin B. Results of the present study demonstrate that current phenotypic methods to identify fungi do not differentiate between genetically distinct species in the A. fumigatus group. Differential antifungal susceptibilities of these species may account for some of the reported poor outcomes of therapy in clinical studies.

scholarly journals Amphotericin B- and Voriconazole-Echinocandin Combinations against Aspergillus spp.: Effect of Serum on Inhibitory and Fungicidal Interactions

2013 ◽  
Vol 57 (10) ◽  
pp. 4656-4663 ◽  
Author(s):  
Antigoni Elefanti ◽  
Johan W. Mouton ◽  
Paul E. Verweij ◽  
Athanassios Tsakris ◽  
Loukia Zerva ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Colorimetric Method ◽  
Antifungal Drugs ◽  
Content Type ◽  
Synergistic Interactions ◽  
Inhibitory Activities ◽  
Additive Interactions ◽  
Species Specific

ABSTRACTAntifungal combination therapy with voriconazole or amphotericin B and an echinocandin is often employed as primary or salvage therapy for management particularly of refractory aspergillosis. The pharmacodynamic interactions of amphotericin B- and voriconazole-based combinations with the three echinocandins caspofungin, micafungin, and anidulafungin in the presence of serum were tested against 15Aspergillus fumigatuscomplex,A. flavuscomplex, andA. terreuscomplex isolates to assess both their growth-inhibitory and fungicidal activities. Thein vitroactivity of each drug alone and in combination at a 1:1 fixed concentration ratio was tested with a broth microdilution colorimetric method, and interactions were assessed by isobolographic analysis. Synergy was found for all amphotericin B- and voriconazole-based combinations, with amphotericin B-based combinations showing strong inhibitory synergistic interactions (interaction indices of 0.20 to 0.52) and with voriconazole-based combinations demonstrating strong fungicidal synergistic interactions (interaction indices of 0.10 to 0.29) (P< 0.001). Drug- and species-specific differences were found, with caspofungin and theA. fumigatuscomplex exhibiting the weakest synergistic interactions. In the presence of serum, the synergistic interactions were reduced in the order (from largest to smallest decrease) micafungin > anidulafungin > caspofungin, andA. flavuscomplex >A. fumigatuscomplex >A. terreuscomplex, resulting in additive interactions, particularly for inhibitory activities of amphotericin B-echinocandin combinations and fungicidal activities of voriconazole-echinocandin combinations. Drug- and species-specific differences were found in the presence of serum for inhibitory activities of antifungal drugs, with the lowest interaction indices being observed for amphotericin B-caspofungin (median, 0.77) and for theA. terreuscomplex (median, 0.56). The presentin vitrodata showed that serum had a major impact on synergistic interactions of amphotericin B-echinocandin and voriconazole-echinocandin combinations, resulting in additive interactions and explaining the indifferent outcomes usually observedin vivo.

scholarly journals Dynamic Interaction between Fluconazole and Amphotericin B against Cryptococcus gattii

2012 ◽  
Vol 56 (5) ◽  
pp. 2553-2558 ◽  
Author(s):  
Julliana Ribeiro Alves Santos ◽  
Ludmila Ferreira Gouveia ◽  
Erika Linzi Silva Taylor ◽  
Maria Aparecida Resende-Stoianoff ◽  
Gerson Antônio Pianetti ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Cryptococcus Gattii ◽  
Content Type ◽  
Antagonistic Interaction ◽  
Ergosterol Content ◽  
Kill Curve ◽  
Time Kill ◽  
Postantifungal Effect

ABSTRACTCryptococcus gattiiis the main pathogen of cryptococcosis in healthy patients and is treated mainly with fluconazole and amphotericin B. The combination of these drugs has been questioned because the mechanisms of action could lead to a theoretical antagonistic interaction. We evaluated distinct parameters involved in thein vitrocombination of fluconazole and amphotericin B againstCryptococcus gattii. Fourteen strains ofC. gattiiwere used for the determination of MIC, fractional inhibitory concentration, time-kill curve, and postantifungal effect (PAFE). Ergosterol quantification was performed to evaluate the influence of ergosterol content on the interaction between these antifungals. Interaction between the drugs varied from synergistic to antagonistic depending on the strain and concentration tested. Increasing fluconazole levels were correlated with an antagonistic interaction. A total of 48 h was necessary for reducing the fungal viability in the presence of fluconazole, while 12 h were required for amphotericin B. When these antifungals were tested in combination, fluconazole impaired the amphotericin B activity. The ergosterol content decreased with the increase of fluconazole levels and it was correlated with the lower activity of amphotericin B. The PAFE found varied from 1 to 4 h for fluconazole and from 1 to 3 h for amphotericin B. The interaction of fluconazole and amphotericin B was concentration-dependent and special attention should be directed when these drugs are used in combination againstC. gattii.

scholarly journals In Vitro and In Vivo Exposure-Effect Relationship of Liposomal Amphotericin B against Aspergillus fumigatus

2019 ◽  
Vol 63 (6) ◽  
Author(s):  
Maria Siopi ◽  
Johan W. Mouton ◽  
Spyros Pournaras ◽  
Joseph Meletiadis
Keyword(s):  
Aspergillus Fumigatus ◽  
Amphotericin B ◽  
Liposomal Amphotericin ◽  
Simulation Analysis ◽  
Maximal Activity ◽  
Liposomal Amphotericin B ◽  
Content Type ◽  
Exposure Effect

ABSTRACT In vitro pharmacokinetic/pharmacodynamic data of liposomal amphotericin B (L-AMB) were compared with animal data from neutropenic and nonneutropenic models of azole-susceptible and azole-resistant invasive aspergillosis. L-AMB was equally effective. The in vitro fCmax (maximum concentration of free drug)/MIC ratio associated with 50% of maximal activity was 0.31 (0.29 to 0.33), similar to that in neutropenic but not nonneutropenic mice (0.11 [0.06 to 0.20]). Simulation analysis indicated that standard L-AMB doses (1 to 3 mg/kg) are adequate for nonneutropenic patients, but higher doses (7.5 to 10 mg/kg) may be required for neutropenic patients for Aspergillus fumigatus isolates with MICs of 0.5 to 1 mg/liter.

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