The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Dimitrios P Kontoyiannis - One of the best experts on this subject based on the ideXlab platform.
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Host Defenses Against Zygomycetes
Clinical Infectious Diseases, 2012Co-Authors: Emmanuel Roilides, Dimitrios P Kontoyiannis, Thomas J. WalshAbstract:Mucormycosis is a devastating disease and can occur in patients with a variety of risk factors, the most important of which are immunosuppression, anatomic barrier breakdown, iron overload, and hyperglycemia/acidosis. Similarly to what occurs with Aspergillus, the host stimulates an innate immune response against the challenging sporangiospores and invading hyphae of Zygomycetes. This article discusses the host defense to different Zygomycetes, its augmentation, and its subsequent impact on the outcome of mucormycosis.
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increased virulence of Zygomycetes organisms following exposure to voriconazole a study involving fly and murine models of zygomycosis
The Journal of Infectious Diseases, 2009Co-Authors: Gregory A Lamaris, Georgios Chamilos, Russell E Lewis, Ronen Benami, George Samonis, Dimitrios P KontoyiannisAbstract:BACKGROUND: Breakthrough zygomycosis is increasingly observed among patients at high risk for fungal infection who are receiving voriconazole, reflecting either selective pressure or voriconazole-associated alterations in Zygomycetes virulence. We tested the latter hypothesis, using 2 phylogenetically disparate zygomycosis models. METHODS: Three Zygomycetes strains were exposed to voriconazole by serial passages on voriconazole-containing medium. The virulence of voriconazole-exposed Zygomycetes strains was compared with that of voriconazole-nonexposed strains in Drosophila and murine models of zygomycosis by assessment of survival curves, pulmonary fungal burdens, and expression of inflammation-associated genes. RESULTS: Among Toll-deficient (Tl(-/-)) and wild-type fruit flies, infection with Zygomycetes isolates that had been exposed to voriconazole yielded significantly lower survival rates than infection with Zygomycetes strains grown in drug-free media. In contrast, exposure of Rhizopus oryzae to itraconazole, amphotericin B, or caspofungin and exposure of Aspergillus fumigatus to voriconazole did not alter the virulence of these isolates in fruit flies. In the murine model, infection with a R. oryzae strain preexposed to voriconazole was associated with decreased survival rates and increased pulmonary fungal burdens, compared with infection with a voriconazole-nonexposed R. oryzae strain. In addition, enhanced angioinvasion, inflammation, and expression of genes involved in stress response and tissue repair were found in mouse lungs infected with voriconazole-exposed R. oryzae. CONCLUSIONS: Exposure of Zygomycetes organisms to voriconazole selectively enhanced their virulence. The mechanisms underlying these phenotypic changes should be studied further.
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drosophila melanogaster as a model host to dissect the immunopathogenesis of zygomycosis
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: Georgios Chamilos, Russell E Lewis, Lianchun Xiao, Tomasz Zal, Michel Gilliet, Georg Halder, Dimitrios P KontoyiannisAbstract:Zygomycosis is an emerging frequently fatal opportunistic mycosis whose immunopathogenesis is poorly understood. We developed a zygomycosis model by injecting Drosophila melanogaster flies with a standardized amount of fungal spores from clinical Zygomycetes isolates to study virulence and host defense mechanisms. We found that, as opposed to most other fungi, which are nonpathogenic in D. melanogaster (e.g., Aspergillus fumigatus), Zygomycetes rapidly infect and kill wild-type flies. Toll-deficient flies exhibited increased susceptibility to Zygomycetes, whereas constitutive overexpression of the antifungal peptide Drosomycin in transgenic flies partially restored resistance to zygomycosis. D. melanogaster Schneider 2 phagocytic cells displayed decreased phagocytosis and caused less hyphal damage to Zygomycetes compared with that to A. fumigatus. Furthermore, phagocytosis-defective eater mutant flies displayed increased susceptibility to Zygomycetes infection. Classic enhancers of Zygomycetes virulence in humans, such as corticosteroids, increased iron supply, and iron availability through treatment with deferoxamine dramatically increased Zygomycetes pathogenicity in our model. In contrast, iron starvation induced by treatment with the iron chelator deferasirox significantly protected flies infected with Zygomycetes. Whole-genome expression profiling in wild-type flies after infection with Zygomycetes vs. A. fumigatus identified genes selectively down-regulated by Zygomycetes, which act in pathogen recognition, immune defense, stress response, detoxification, steroid metabolism, or tissue repair or have unknown functions. Our results provide insights into the factors that mediate host–pathogen interactions in zygomycosis and establish D. melanogaster as a promising model to study this important mycosis.
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Increased culture recovery of Zygomycetes under physiologic temperature conditions.
American journal of clinical pathology, 2007Co-Authors: Dimitrios P Kontoyiannis, Georgios Chamilos, Russell E Lewis, Saad A. Hassan, Nathaniel D. Albert, Jeffrey J. TarrandAbstract:Poor recovery of Zygomycetes hyphae from tissue specimens may result from failure of current culture methods to mimic physiologic conditions found in hyphae-laden infected tissue. We describe the use of an in vitro model simulating Zygomycetes growth under necrotic or hypoxic tissue conditions. We preconditioned hyphae of clinical Zygomycetes isolates in flasks under anaerobic conditions using Ana-Packs (Becton Dickinson Microbiology Systems, Sparks, MD) at 37 degrees C for 48 hours, thus simulating in vivo growth in an infracted hypoxic lesion, and compared the recovery of paired inocula at 37 degrees C and 25 degrees C. Incubation of stock culture isolates at 37 degrees C resulted in significantly better culture recovery (about 10-fold) when compared with incubation at 25 degrees C (P < .0001). In addition, we similarly evaluated 25, 291 consecutive clinical specimens. Among 41 specimens, the yield of Zygomycetes cultures incubated at 37 degrees C (23/41 [56%]) was significantly higher than that incubated at 25 degrees C (9/41 [22%]; P = .0001). Overall, we found that culture recovery was significantly (254%) enhanced at 37 degrees C.
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Lovastatin Has Significant Activity against Zygomycetes and Interacts Synergistically with Voriconazole
Antimicrobial agents and chemotherapy, 2006Co-Authors: Georgios Chamilos, Russell E Lewis, Dimitrios P KontoyiannisAbstract:Zygomycetes are emerging opportunistic molds resistant to most conventional antifungals. We evaluated the in vitro activity of lovastatin (LOV), a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, against seven clinical isolates of Zygomycetes by using standard microdilution methods in three different media, disk diffusion testing, and viability dye staining. To further study the in vivo efficacy of LOV against Zygomycetes, we developed a Drosophila melanogaster model of zygomycosis. In different experiments, groups of Toll-deficient ( Tl ) flies fed LOV-containing food were subsequently injected with two representative Zygomycetes isolates ( Mucor and Rhizopus spp.). Finally, we examined the effects of LOV on voriconazole (VRC) activity against Zygomycetes in vitro by checkerboard dilution, Epsilometer test-based methods, and bis-(1,3-dibutylbarbituric acid) trimethine oxonol staining and in vivo in Tl flies fed food containing LOV plus VRC and infected with Zygomycetes. LOV exhibited significant, medium, and strain-independent fungicidal activity against all Zygomycetes isolates in vitro by all testing methods (MIC 50 , 48.0 μg/ml; 50% minimal fungicidal concentration, 56.0 μg/ml; 50% effective concentration, 29.4 μg/ml [6.6 to 38.9 μg/ml]). Tl flies fed LOV-containing food and infected with Mucor had a significantly better 6-day survival rate than did infected Tl flies fed regular food ( P = 0.0005). LOV displayed in vitro synergy with VRC against all Zygomycetes isolates (fractional inhibitory concentration index, 0.104 to 0.290) by all methods used. LOV also displayed synergy with VRC in the Drosophila model of zygomycosis ( P
Eric Dannaoui - One of the best experts on this subject based on the ideXlab platform.
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in vitro interactions between antifungals and immunosuppressive drugs against Zygomycetes
Antimicrobial Agents and Chemotherapy, 2009Co-Authors: Patrick Schwarz, Olivier Lortholary, Eric DannaouiAbstract:The in vitro interaction of antifungals with immunosuppressive drugs was evaluated against Zygomycetes. The combination of amphotericin B with cyclosporine, rapamycin, or tacrolimus was synergistic for 90%, 70%, and 30% of the isolates, respectively. For posaconazole, itraconazole, and ravuconazole, synergy was more frequently observed with cyclosporine than with rapamycin or tacrolimus and antagonistic interactions were rarely noted. In summary, calcineurin inhibitors and rapamycin can be synergistic in vitro with amphotericin B and azoles against Zygomycetes.
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Molecular tools for identification of Zygomycetes and the diagnosis of zygomycosis.
Clinical Microbiology and Infection, 2009Co-Authors: Eric DannaouiAbstract:The identification of Zygomycetes and diagnosis of zygomycosis are notoriously difficult. However, there have been recent advances, particularly in the availability and evaluation of new molecular approaches. Two main issues are of importance: the identification to species level of a strain isolated in culture, and the identification of a zygomycete in tissues. By using several molecular targets and by increasing the number of available DNA sequences in international databases, several studies have shown that accurate molecular identification of Zygomycetes to species level is feasible. The internal transcribed spacer (ITS) region may be used as a first-line molecular target for the identification of Zygomycetes in pure culture. However, cultures from infected tissues are often negative and the different Zygomycetes share similar morphology according to histopathology. Furthermore, differentiation of a zygomycete from another hyalohyphomycete can sometimes be difficult in histopathology. Thus, alternative methods for the diagnosis of zygomycosis and for species identification directly from tissues are needed. For this purpose, molecular methods have been recently evaluated, both on unfixed fresh/frozen material and on formalin-fixed, paraffin-embedded biopsies. This review discusses the molecular approaches currently available for the identification of Zygomycetes and the diagnosis of zygomycosis.
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Carbon Assimilation Profiles as a Tool for Identification of Zygomycetes
Journal of clinical microbiology, 2007Co-Authors: Patrick Schwarz, Olivier Lortholary, Françoise Dromer, Eric DannaouiAbstract:Identification of Zygomycetes is difficult and time-consuming by standard microbiological procedures. Carbon assimilation profiles are commonly used for yeast-and bacterial-species identification but rarely for filamentous-fungus identification. Carbon assimilation profiles were evaluated using the commercialized kits ID32C and API 50 CH, which contain 31 and 49 tests, respectively, to serve as simple tools for species identification of Zygomycetes in clinical microbiology laboratories. Fifty-seven strains belonging to 15 species and varieties of Zygomycetes, including Rhizopus, Absidia, Mucor, and Rhizomucor species, were tested for intra- and interspecies variability based on their carbon assimilation profiles. Using ID32C strips, 6 tests were always positive, 7 were never positive, and 18 showed consistently different results between species. With API 50 CH strips, 15 tests were positive for all species, 13 were never positive, and 21 showed different results between species. Nevertheless, assimilation patterns were highly variable among Rhizopus oryzae isolates, and it was not possible to define a specific carbon assimilation profile. With both ID32C and API CH 50 strips, intraspecies variation was found to be low, while large differences were found between genera and species. The clustering of isolates based on their carbon assimilation profiles was in accordance with DNA-based phylogeny of Zygomycetes. In conclusion, carbon assimilation profiles allowed precise and accurate identification of most Zygomycetes to the species level.
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Molecular identification of Zygomycetes from culture and experimentally infected tissues
Journal of Clinical Microbiology, 2006Co-Authors: Patrick Schwarz, Stéphane Bretagne, Jean-charles Gantier, Dea Garcia-hermoso, Olivier Lortholary, Françoise Dromer, Eric DannaouiAbstract:Mucormycosis is an emerging infection associated with a high mortality rate. Identification of the causative agents remains difficult and time-consuming by standard mycological procedures. In this study, internal transcribed spacer (ITS) sequencing was validated as a reliable technique for identification of Zygomycetes to the species level. Furthermore, species identification directly from infected tissues was evaluated in experimentally infected mice. Fifty-four Zygomycetes strains belonging to 16 species, including the most common pathogenic species of Rhizopus spp., Absidia spp., Mucor spp., and Rhizomucor spp., were used to assess intra-and interspecies variability. Ribosomal DNA including the complete ITS1-5.8S-ITS2 region was amplified with fungal universal primers, sequenced, and compared. Overall, for a given species, sequence similarities between isolates were > 98%. In contrast, ITS sequences were very different between species, allowing an accurate identification of Zygomycetes to the species level in most cases. Six species (Rhizopus oryzae, Rhizopus microsporus, Rhizomucor pusillus, Mucor circinelloides, and Mucor indicus) were also used to induce disseminated mucormycosis in mice and to demonstrate that DNA extraction, amplification of fungal DNA, sequencing, and molecular identification were possible directly from frozen tissues.
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activity of posaconazole in treatment of experimental disseminated zygomycosis
Antimicrobial Agents and Chemotherapy, 2003Co-Authors: Eric Dannaoui, Jacques F. Meis, David Loebenberg, Paul E VerweijAbstract:Three isolates of Zygomycetes were used to produce a disseminated infection in nonimmunocompromised mice. Against all zygomycete strains, amphotericin B significantly prolonged survival. Itraconazole was inactive against Rhizopus microsporus and Rhizopus oryzae but was partially active against Absidia corymbifera. Posaconazole had no beneficial effects against R. oryzae but showed partial activity against A. corymbifera. Posaconazole had a clear dose-response effect against R. microsporus.
Russell E Lewis - One of the best experts on this subject based on the ideXlab platform.
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increased virulence of Zygomycetes organisms following exposure to voriconazole a study involving fly and murine models of zygomycosis
The Journal of Infectious Diseases, 2009Co-Authors: Gregory A Lamaris, Georgios Chamilos, Russell E Lewis, Ronen Benami, George Samonis, Dimitrios P KontoyiannisAbstract:BACKGROUND: Breakthrough zygomycosis is increasingly observed among patients at high risk for fungal infection who are receiving voriconazole, reflecting either selective pressure or voriconazole-associated alterations in Zygomycetes virulence. We tested the latter hypothesis, using 2 phylogenetically disparate zygomycosis models. METHODS: Three Zygomycetes strains were exposed to voriconazole by serial passages on voriconazole-containing medium. The virulence of voriconazole-exposed Zygomycetes strains was compared with that of voriconazole-nonexposed strains in Drosophila and murine models of zygomycosis by assessment of survival curves, pulmonary fungal burdens, and expression of inflammation-associated genes. RESULTS: Among Toll-deficient (Tl(-/-)) and wild-type fruit flies, infection with Zygomycetes isolates that had been exposed to voriconazole yielded significantly lower survival rates than infection with Zygomycetes strains grown in drug-free media. In contrast, exposure of Rhizopus oryzae to itraconazole, amphotericin B, or caspofungin and exposure of Aspergillus fumigatus to voriconazole did not alter the virulence of these isolates in fruit flies. In the murine model, infection with a R. oryzae strain preexposed to voriconazole was associated with decreased survival rates and increased pulmonary fungal burdens, compared with infection with a voriconazole-nonexposed R. oryzae strain. In addition, enhanced angioinvasion, inflammation, and expression of genes involved in stress response and tissue repair were found in mouse lungs infected with voriconazole-exposed R. oryzae. CONCLUSIONS: Exposure of Zygomycetes organisms to voriconazole selectively enhanced their virulence. The mechanisms underlying these phenotypic changes should be studied further.
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drosophila melanogaster as a model host to dissect the immunopathogenesis of zygomycosis
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: Georgios Chamilos, Russell E Lewis, Lianchun Xiao, Tomasz Zal, Michel Gilliet, Georg Halder, Dimitrios P KontoyiannisAbstract:Zygomycosis is an emerging frequently fatal opportunistic mycosis whose immunopathogenesis is poorly understood. We developed a zygomycosis model by injecting Drosophila melanogaster flies with a standardized amount of fungal spores from clinical Zygomycetes isolates to study virulence and host defense mechanisms. We found that, as opposed to most other fungi, which are nonpathogenic in D. melanogaster (e.g., Aspergillus fumigatus), Zygomycetes rapidly infect and kill wild-type flies. Toll-deficient flies exhibited increased susceptibility to Zygomycetes, whereas constitutive overexpression of the antifungal peptide Drosomycin in transgenic flies partially restored resistance to zygomycosis. D. melanogaster Schneider 2 phagocytic cells displayed decreased phagocytosis and caused less hyphal damage to Zygomycetes compared with that to A. fumigatus. Furthermore, phagocytosis-defective eater mutant flies displayed increased susceptibility to Zygomycetes infection. Classic enhancers of Zygomycetes virulence in humans, such as corticosteroids, increased iron supply, and iron availability through treatment with deferoxamine dramatically increased Zygomycetes pathogenicity in our model. In contrast, iron starvation induced by treatment with the iron chelator deferasirox significantly protected flies infected with Zygomycetes. Whole-genome expression profiling in wild-type flies after infection with Zygomycetes vs. A. fumigatus identified genes selectively down-regulated by Zygomycetes, which act in pathogen recognition, immune defense, stress response, detoxification, steroid metabolism, or tissue repair or have unknown functions. Our results provide insights into the factors that mediate host–pathogen interactions in zygomycosis and establish D. melanogaster as a promising model to study this important mycosis.
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Increased culture recovery of Zygomycetes under physiologic temperature conditions.
American journal of clinical pathology, 2007Co-Authors: Dimitrios P Kontoyiannis, Georgios Chamilos, Russell E Lewis, Saad A. Hassan, Nathaniel D. Albert, Jeffrey J. TarrandAbstract:Poor recovery of Zygomycetes hyphae from tissue specimens may result from failure of current culture methods to mimic physiologic conditions found in hyphae-laden infected tissue. We describe the use of an in vitro model simulating Zygomycetes growth under necrotic or hypoxic tissue conditions. We preconditioned hyphae of clinical Zygomycetes isolates in flasks under anaerobic conditions using Ana-Packs (Becton Dickinson Microbiology Systems, Sparks, MD) at 37 degrees C for 48 hours, thus simulating in vivo growth in an infracted hypoxic lesion, and compared the recovery of paired inocula at 37 degrees C and 25 degrees C. Incubation of stock culture isolates at 37 degrees C resulted in significantly better culture recovery (about 10-fold) when compared with incubation at 25 degrees C (P < .0001). In addition, we similarly evaluated 25, 291 consecutive clinical specimens. Among 41 specimens, the yield of Zygomycetes cultures incubated at 37 degrees C (23/41 [56%]) was significantly higher than that incubated at 25 degrees C (9/41 [22%]; P = .0001). Overall, we found that culture recovery was significantly (254%) enhanced at 37 degrees C.
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Lovastatin Has Significant Activity against Zygomycetes and Interacts Synergistically with Voriconazole
Antimicrobial agents and chemotherapy, 2006Co-Authors: Georgios Chamilos, Russell E Lewis, Dimitrios P KontoyiannisAbstract:Zygomycetes are emerging opportunistic molds resistant to most conventional antifungals. We evaluated the in vitro activity of lovastatin (LOV), a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, against seven clinical isolates of Zygomycetes by using standard microdilution methods in three different media, disk diffusion testing, and viability dye staining. To further study the in vivo efficacy of LOV against Zygomycetes, we developed a Drosophila melanogaster model of zygomycosis. In different experiments, groups of Toll-deficient ( Tl ) flies fed LOV-containing food were subsequently injected with two representative Zygomycetes isolates ( Mucor and Rhizopus spp.). Finally, we examined the effects of LOV on voriconazole (VRC) activity against Zygomycetes in vitro by checkerboard dilution, Epsilometer test-based methods, and bis-(1,3-dibutylbarbituric acid) trimethine oxonol staining and in vivo in Tl flies fed food containing LOV plus VRC and infected with Zygomycetes. LOV exhibited significant, medium, and strain-independent fungicidal activity against all Zygomycetes isolates in vitro by all testing methods (MIC 50 , 48.0 μg/ml; 50% minimal fungicidal concentration, 56.0 μg/ml; 50% effective concentration, 29.4 μg/ml [6.6 to 38.9 μg/ml]). Tl flies fed LOV-containing food and infected with Mucor had a significantly better 6-day survival rate than did infected Tl flies fed regular food ( P = 0.0005). LOV displayed in vitro synergy with VRC against all Zygomycetes isolates (fractional inhibitory concentration index, 0.104 to 0.290) by all methods used. LOV also displayed synergy with VRC in the Drosophila model of zygomycosis ( P
Georgios Chamilos - One of the best experts on this subject based on the ideXlab platform.
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increased virulence of Zygomycetes organisms following exposure to voriconazole a study involving fly and murine models of zygomycosis
The Journal of Infectious Diseases, 2009Co-Authors: Gregory A Lamaris, Georgios Chamilos, Russell E Lewis, Ronen Benami, George Samonis, Dimitrios P KontoyiannisAbstract:BACKGROUND: Breakthrough zygomycosis is increasingly observed among patients at high risk for fungal infection who are receiving voriconazole, reflecting either selective pressure or voriconazole-associated alterations in Zygomycetes virulence. We tested the latter hypothesis, using 2 phylogenetically disparate zygomycosis models. METHODS: Three Zygomycetes strains were exposed to voriconazole by serial passages on voriconazole-containing medium. The virulence of voriconazole-exposed Zygomycetes strains was compared with that of voriconazole-nonexposed strains in Drosophila and murine models of zygomycosis by assessment of survival curves, pulmonary fungal burdens, and expression of inflammation-associated genes. RESULTS: Among Toll-deficient (Tl(-/-)) and wild-type fruit flies, infection with Zygomycetes isolates that had been exposed to voriconazole yielded significantly lower survival rates than infection with Zygomycetes strains grown in drug-free media. In contrast, exposure of Rhizopus oryzae to itraconazole, amphotericin B, or caspofungin and exposure of Aspergillus fumigatus to voriconazole did not alter the virulence of these isolates in fruit flies. In the murine model, infection with a R. oryzae strain preexposed to voriconazole was associated with decreased survival rates and increased pulmonary fungal burdens, compared with infection with a voriconazole-nonexposed R. oryzae strain. In addition, enhanced angioinvasion, inflammation, and expression of genes involved in stress response and tissue repair were found in mouse lungs infected with voriconazole-exposed R. oryzae. CONCLUSIONS: Exposure of Zygomycetes organisms to voriconazole selectively enhanced their virulence. The mechanisms underlying these phenotypic changes should be studied further.
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drosophila melanogaster as a model host to dissect the immunopathogenesis of zygomycosis
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: Georgios Chamilos, Russell E Lewis, Lianchun Xiao, Tomasz Zal, Michel Gilliet, Georg Halder, Dimitrios P KontoyiannisAbstract:Zygomycosis is an emerging frequently fatal opportunistic mycosis whose immunopathogenesis is poorly understood. We developed a zygomycosis model by injecting Drosophila melanogaster flies with a standardized amount of fungal spores from clinical Zygomycetes isolates to study virulence and host defense mechanisms. We found that, as opposed to most other fungi, which are nonpathogenic in D. melanogaster (e.g., Aspergillus fumigatus), Zygomycetes rapidly infect and kill wild-type flies. Toll-deficient flies exhibited increased susceptibility to Zygomycetes, whereas constitutive overexpression of the antifungal peptide Drosomycin in transgenic flies partially restored resistance to zygomycosis. D. melanogaster Schneider 2 phagocytic cells displayed decreased phagocytosis and caused less hyphal damage to Zygomycetes compared with that to A. fumigatus. Furthermore, phagocytosis-defective eater mutant flies displayed increased susceptibility to Zygomycetes infection. Classic enhancers of Zygomycetes virulence in humans, such as corticosteroids, increased iron supply, and iron availability through treatment with deferoxamine dramatically increased Zygomycetes pathogenicity in our model. In contrast, iron starvation induced by treatment with the iron chelator deferasirox significantly protected flies infected with Zygomycetes. Whole-genome expression profiling in wild-type flies after infection with Zygomycetes vs. A. fumigatus identified genes selectively down-regulated by Zygomycetes, which act in pathogen recognition, immune defense, stress response, detoxification, steroid metabolism, or tissue repair or have unknown functions. Our results provide insights into the factors that mediate host–pathogen interactions in zygomycosis and establish D. melanogaster as a promising model to study this important mycosis.
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Increased culture recovery of Zygomycetes under physiologic temperature conditions.
American journal of clinical pathology, 2007Co-Authors: Dimitrios P Kontoyiannis, Georgios Chamilos, Russell E Lewis, Saad A. Hassan, Nathaniel D. Albert, Jeffrey J. TarrandAbstract:Poor recovery of Zygomycetes hyphae from tissue specimens may result from failure of current culture methods to mimic physiologic conditions found in hyphae-laden infected tissue. We describe the use of an in vitro model simulating Zygomycetes growth under necrotic or hypoxic tissue conditions. We preconditioned hyphae of clinical Zygomycetes isolates in flasks under anaerobic conditions using Ana-Packs (Becton Dickinson Microbiology Systems, Sparks, MD) at 37 degrees C for 48 hours, thus simulating in vivo growth in an infracted hypoxic lesion, and compared the recovery of paired inocula at 37 degrees C and 25 degrees C. Incubation of stock culture isolates at 37 degrees C resulted in significantly better culture recovery (about 10-fold) when compared with incubation at 25 degrees C (P < .0001). In addition, we similarly evaluated 25, 291 consecutive clinical specimens. Among 41 specimens, the yield of Zygomycetes cultures incubated at 37 degrees C (23/41 [56%]) was significantly higher than that incubated at 25 degrees C (9/41 [22%]; P = .0001). Overall, we found that culture recovery was significantly (254%) enhanced at 37 degrees C.
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Lovastatin Has Significant Activity against Zygomycetes and Interacts Synergistically with Voriconazole
Antimicrobial agents and chemotherapy, 2006Co-Authors: Georgios Chamilos, Russell E Lewis, Dimitrios P KontoyiannisAbstract:Zygomycetes are emerging opportunistic molds resistant to most conventional antifungals. We evaluated the in vitro activity of lovastatin (LOV), a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, against seven clinical isolates of Zygomycetes by using standard microdilution methods in three different media, disk diffusion testing, and viability dye staining. To further study the in vivo efficacy of LOV against Zygomycetes, we developed a Drosophila melanogaster model of zygomycosis. In different experiments, groups of Toll-deficient ( Tl ) flies fed LOV-containing food were subsequently injected with two representative Zygomycetes isolates ( Mucor and Rhizopus spp.). Finally, we examined the effects of LOV on voriconazole (VRC) activity against Zygomycetes in vitro by checkerboard dilution, Epsilometer test-based methods, and bis-(1,3-dibutylbarbituric acid) trimethine oxonol staining and in vivo in Tl flies fed food containing LOV plus VRC and infected with Zygomycetes. LOV exhibited significant, medium, and strain-independent fungicidal activity against all Zygomycetes isolates in vitro by all testing methods (MIC 50 , 48.0 μg/ml; 50% minimal fungicidal concentration, 56.0 μg/ml; 50% effective concentration, 29.4 μg/ml [6.6 to 38.9 μg/ml]). Tl flies fed LOV-containing food and infected with Mucor had a significantly better 6-day survival rate than did infected Tl flies fed regular food ( P = 0.0005). LOV displayed in vitro synergy with VRC against all Zygomycetes isolates (fractional inhibitory concentration index, 0.104 to 0.290) by all methods used. LOV also displayed synergy with VRC in the Drosophila model of zygomycosis ( P
Olivier Lortholary - One of the best experts on this subject based on the ideXlab platform.
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in vitro interactions between antifungals and immunosuppressive drugs against Zygomycetes
Antimicrobial Agents and Chemotherapy, 2009Co-Authors: Patrick Schwarz, Olivier Lortholary, Eric DannaouiAbstract:The in vitro interaction of antifungals with immunosuppressive drugs was evaluated against Zygomycetes. The combination of amphotericin B with cyclosporine, rapamycin, or tacrolimus was synergistic for 90%, 70%, and 30% of the isolates, respectively. For posaconazole, itraconazole, and ravuconazole, synergy was more frequently observed with cyclosporine than with rapamycin or tacrolimus and antagonistic interactions were rarely noted. In summary, calcineurin inhibitors and rapamycin can be synergistic in vitro with amphotericin B and azoles against Zygomycetes.
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Carbon Assimilation Profiles as a Tool for Identification of Zygomycetes
Journal of clinical microbiology, 2007Co-Authors: Patrick Schwarz, Olivier Lortholary, Françoise Dromer, Eric DannaouiAbstract:Identification of Zygomycetes is difficult and time-consuming by standard microbiological procedures. Carbon assimilation profiles are commonly used for yeast-and bacterial-species identification but rarely for filamentous-fungus identification. Carbon assimilation profiles were evaluated using the commercialized kits ID32C and API 50 CH, which contain 31 and 49 tests, respectively, to serve as simple tools for species identification of Zygomycetes in clinical microbiology laboratories. Fifty-seven strains belonging to 15 species and varieties of Zygomycetes, including Rhizopus, Absidia, Mucor, and Rhizomucor species, were tested for intra- and interspecies variability based on their carbon assimilation profiles. Using ID32C strips, 6 tests were always positive, 7 were never positive, and 18 showed consistently different results between species. With API 50 CH strips, 15 tests were positive for all species, 13 were never positive, and 21 showed different results between species. Nevertheless, assimilation patterns were highly variable among Rhizopus oryzae isolates, and it was not possible to define a specific carbon assimilation profile. With both ID32C and API CH 50 strips, intraspecies variation was found to be low, while large differences were found between genera and species. The clustering of isolates based on their carbon assimilation profiles was in accordance with DNA-based phylogeny of Zygomycetes. In conclusion, carbon assimilation profiles allowed precise and accurate identification of most Zygomycetes to the species level.
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Molecular identification of Zygomycetes from culture and experimentally infected tissues
Journal of Clinical Microbiology, 2006Co-Authors: Patrick Schwarz, Stéphane Bretagne, Jean-charles Gantier, Dea Garcia-hermoso, Olivier Lortholary, Françoise Dromer, Eric DannaouiAbstract:Mucormycosis is an emerging infection associated with a high mortality rate. Identification of the causative agents remains difficult and time-consuming by standard mycological procedures. In this study, internal transcribed spacer (ITS) sequencing was validated as a reliable technique for identification of Zygomycetes to the species level. Furthermore, species identification directly from infected tissues was evaluated in experimentally infected mice. Fifty-four Zygomycetes strains belonging to 16 species, including the most common pathogenic species of Rhizopus spp., Absidia spp., Mucor spp., and Rhizomucor spp., were used to assess intra-and interspecies variability. Ribosomal DNA including the complete ITS1-5.8S-ITS2 region was amplified with fungal universal primers, sequenced, and compared. Overall, for a given species, sequence similarities between isolates were > 98%. In contrast, ITS sequences were very different between species, allowing an accurate identification of Zygomycetes to the species level in most cases. Six species (Rhizopus oryzae, Rhizopus microsporus, Rhizomucor pusillus, Mucor circinelloides, and Mucor indicus) were also used to induce disseminated mucormycosis in mice and to demonstrate that DNA extraction, amplification of fungal DNA, sequencing, and molecular identification were possible directly from frozen tissues.
