59 research outputs found
Optimization of the treatment of invasive fungal infections in the era of antifungal resistance : development of an alternative in vivo model to test the therapeutic efficacy of azoles
No full textL’aspergillose invasive (AI) est une pathologie grave dont la prise en charge est compliquée du fait de l’émergence des résistances au traitement de première ligne (azolés). Ces résistances sont liées aux traitements antifongiques (ATF) aux long cours chez les patients et à la sélection dans l’environnement par l’utilisation de fongicides en milieu agricole. Des alternatives sont indispensables pour la prise en charge des AI. Les associations d’ATF représentent une piste thérapeutique intéressante mais qui doit être validée in vivo. Par ailleurs, dans de nombreux pays et notamment en Tunisie, l’épidémiologie des résistances aux azolés chez Aspergillus reste peu connue.L’objectif de ma thèse était de développer un modèle d’AI chez Galleria mellonella pour évaluer l’efficacité de nouvelles stratégies thérapeutiques et de dépister des souches résistantes d’Aspergillus spp. aux azolés à partir de souches cliniques et environnementales en Tunisie.Nous avons utilisé 3 souches cliniques d’Aspergillus fumigatus (Af) : AfS (sensible à tous les azolés), AfR1(sensible au voriconazole (VRZ), résistante au posaconazole (PSZ)) et AfR2 (R au VRZ et PSZ). Des groupes de 10 larves de Gm ont été infectés par la dose létale correspondante à chaque souche. Les groupes de larves ont été d’abord traités en monothérapie par de l’amphotéricine B (AMB, 0,5 à 4 µg/larve), du VRZ (0,5 à 8 µg/larve), de la caspofungine (CAS 1 à 8 µg/larve) et du PSZ (1 à 8 µg/larve). L’efficacité était évaluée par la mortalité et sur des coupes histopathologiques. Pour tester les associations, les groupes de larves ont été traités par VRZ ou PSZ à 4 μg/larve en monothérapie ou bien en association avec de la CAS à 4, 2 ou 1 μg/larve.La mortalité des larves non traitées était ≥ 95% pour les 3 souches. Une diminution dose dépendante de la mortalité était obtenue par le traitement ATF. Le VRZ était plus efficace pour les larves infectées par les souches sensibles au VRZ (60% de mortalité) que pour les souches résistantes (95% de mortalité). Sur les coupes histologiques et après traitement par le VRZ, les lésions étaient moins disséminées pour AfS que pour AfR2. Le traitement par PSZ a augmenté la survie pour AfS et AfR1 mais pas pour les larves infectées par AfR2. L’association VRZ plus CAS avait un apport significatif par rapport au VRZ seul pour le traitement des larves infectées par AfR2 mais pas pour AfS ou AfR1. L’association PSZ + CAS a augmenté significativement la survie des larves infectées par AfR2 comparé à la monothérapie par CAS ou PSZ.En Tunisie, Nous avons collecté des souches cliniques d’Aspergillus spp., isolées chez des patients et des souches environnementales isolées de prélèvements de sol et d’air. Un criblage des souches résistantes aux azolés a été réalisé sur un milieu de culture contenant des antifongiques. Pour les souches qui ont poussé en présence d’azolés, la CMI a été déterminée par des bandelettes à gradient de concentration et par la technique de référence de dilution en milieu liquide EUCAST.Nous avons collecté 1063 souches d’Aspergillus spp. à partir de prélèvements d’air et de sol. Af et A. flavus représentaient 19 et 5% des souches respectivement. A. niger était l’espèce la plus fréquente (36.6%). Le screening a été réalisé pour 112 souches cliniques (87 A. flavus et 25 Af) et pour 26 souches environnementales (11 A. flavus et 25 Af). Seulement deux souches cliniques d’Af isolées à partir de lavage bronchoalvéolaire de deux patients avaient des CMI à 8 µg/mL pour VRZ et ITZ.G. mellonella est un modèle adapté et intéressant pour l’évaluation de nouvelles stratégies thérapeutiques. Nous avons montré que des associations de CAS avec les azolés permettait d’améliorer la survie des larves infectées par des souches résistantes d’Af. Nous avons également montré que la résistance aux azolés était présente en Tunisie chez des souches d’origine clinique.Invasive aspergillosis (IA) is a serious pathology whose management is complicated by the emergence of resistance to first-line treatment (azoles). These resistances are related to long-term antifungal treatments (AFT) in patients and to environmental selection through the use of fungicides in agricultural settings. Alternatives are essential for management of IA. Combinations of AFT represent an interesting therapeutic option that must be validated in vivo. Moreover, in many countries, and particularly in Tunisia, the epidemiology of resistance to azoles in Aspergillus remains poorly studied. The aim of my thesis was to develop an IA model in G. mellonella (Gm) to evaluate the effectiveness of new therapeutic strategies and to detect resistant strains of Aspergillus spp. to azoles from clinical and environmental strains in Tunisia.We used 3 clinical strains of Aspergillus fumigatus (Af): AfS (azole-susceptible), AfR1 (voriconazole (VRZ) susceptible, posaconazole (PSZ) resistant) and AfR2 (resistant to VRZ and PSZ). Groups of 10 Gm larvae were infected with the corresponding lethal dose for each strain. The larval groups were initially treated with monotherapies with amphotericin B (AMB, 0.5-4 µg/larva), VRZ (0.5-8 µg/larva), caspofungin (CAS 1-8 µg/larva) and PSZ (1-8 µg/larva). Efficacy was assessed by mortality and on histopathological sections. Groups of larvae were treated with VRZ or PSZ at 4 μg/larvae as monotherapy or in combination with CAP at 4, 2 or 1 μg/larva.Mortality of untreated larvae was > 95% for all 3 strains. A dose-dependent mortality decrease was obtained through AFT treatment. VRZ was more effective for larvae infected with VRZ-susceptible strains (60% mortality) than for resistant strains (95% of mortality).On histological sections and after VRZ treatment, lesions were less disseminated for AfS-infected larvae compared to AfR2. Treatment with PSZ increased survival for AfS and AfR1 but not for AfR2 infected larvae. The combination VRZ and CAS had a significant contribution compared to VRZ alone for the treatment of AfR2 but not for AfS or AfR1 infected larvae. The combination of PSZ and CAS significantly increased survival of AfR2-infected larvae compared to CAS and PSZ monotherapy.In Tunisia, we collected clinical strains of Aspergillus spp. isolated from patients and environmental strains isolated from soil and air samples. A screening of azole resistant strains was carried out on a culture medium containing antifungals. For strains that grew in the presence of azoles, the MIC was determined by concentration gradient strips and by the EUCAST liquid dilution reference technique.We collected 1063 strains of Aspergillus spp. from air and soil sampling. Af and A. flavus represented 19 and 5% of the strains respectively. A. niger was the most common species (36.6%). Screening was carried out for 112 clinical strains (87 A. flavus and 25 Af) and 26 environmental strains (11 A. flavus and 25 Af). Only two clinical strains of Af isolated from bronchoalveolar lavage of two patients had MIC at 8 µg/mL for VRZ and ITZ.G. mellonella is a suitable and interesting model for evaluating new therapeutic strategies. We showed that CAS associations with azoles improved the survival of larvae infected with resistant strains of Af. We also showed that resistance to azoles was present in Tunisia in strains of clinical origin
Galleria mellonella for the Evaluation of Antifungal Efficacy against Medically Important Fungi, a Narrative Review
No full textThe treatment of invasive fungal infections remains challenging and the emergence of new fungal pathogens as well as the development of resistance to the main antifungal drugs highlight the need for novel therapeutic strategies. Although in vitro antifungal susceptibility testing has come of age, the proper evaluation of therapeutic efficacy of current or new antifungals is dependent on the use of animal models. Mammalian models, particularly using rodents, are the cornerstone for evaluation of antifungal efficacy, but are limited by increased costs and ethical considerations. To circumvent these limitations, alternative invertebrate models, such as Galleria mellonella, have been developed. Larvae of G. mellonella have been widely used for testing virulence of fungi and more recently have proven useful for evaluation of antifungal efficacy. This model is suitable for infection by different fungal pathogens including yeasts (Candida, Cryptococcus, Trichosporon) and filamentous fungi (Aspergillus, Mucorales). Antifungal efficacy may be easily estimated by fungal burden or mortality rate in infected and treated larvae. The aim of the present review is to summarize the actual data about the use of G. mellonella for testing the in vivo efficacy of licensed antifungal drugs, new drugs, and combination therapies
Paludisme post-transfusionnel chez un patient allogreffé de cellules souches hématopoïétiques (CSH)
No full textIn vitro and in vivo evaluation of antifungal combinations against azole-resistant Aspergillus fumigatus isolates
No full textAzole resistance in Aspergillus fumigatus (Af) has become a widespread threat and a major concern for optimal management of patients with invasive aspergillosis (IA). Combination of echinocandins with azoles is an attractive alternative option for the treatment of IA due to azole-resistant Af strains. The aim of this study was to evaluate the in vitro and in vivo combination of caspofungin (CAS) with either voriconazole (VRZ) or posaconazole (PSZ). In vitro interactions were assessed by two methods, and an animal model of IA in Galleria mellonella was used for in vivo evaluation. Assessment of efficacy was based on larvae mortality. Groups of 10 larvae were infected by 3 clinical strains of Af (azole susceptible, AfS; PSZ resistant, AfR1; VRZ and PSZ resistant strain, AfR2). In vitro, combination of CAS and azoles was indifferent against AfS, and AfR2, and a synergy was found for AfR1. When compared to VRZ monotherapy, the combination of VRZ at 4 µg/larva with CAS at 4 µg/larva improved survival of AfR2-infected larvae (p=0.0066). Combination of PSZ at 4µg/larva with CAS at 4 µg/larva improved survival of AfR1-infected larvae compared to CAS (p=0.0002) and PSZ (0.0024) monotherapy. Antagonism was never observed. In conclusion, the combination of caspofungin with azoles is a promising alternative for the treatment of azole resistant strains of Af
In vitro and in vivo evaluation of antifungal combinations against azole-resistant Aspergillus fumigatus isolates
No full textAzole resistance in Aspergillus fumigatus (Af) has become a widespread threat and a major concern for optimal management of patients with invasive aspergillosis (IA). Combination of echinocandins with azoles is an attractive alternative option for the treatment of IA due to azole-resistant Af strains. The aim of this study was to evaluate the in vitro and in vivo combination of caspofungin (CAS) with either voriconazole (VRZ) or posaconazole (PSZ). In vitro interactions were assessed by two methods, and an animal model of IA in Galleria mellonella was used for in vivo evaluation. Assessment of efficacy was based on larvae mortality. Groups of 10 larvae were infected by 3 clinical strains of Af (azole susceptible, AfS; PSZ resistant, AfR1; VRZ and PSZ resistant strain, AfR2). In vitro, combination of CAS and azoles was indifferent against AfS, and AfR2, and a synergy was found for AfR1. When compared to VRZ monotherapy, the combination of VRZ at 4 µg/larva with CAS at 4 µg/larva improved survival of AfR2-infected larvae (p=0.0066). Combination of PSZ at 4µg/larva with CAS at 4 µg/larva improved survival of AfR1-infected larvae compared to CAS (p=0.0002) and PSZ (0.0024) monotherapy. Antagonism was never observed. In conclusion, the combination of caspofungin with azoles is a promising alternative for the treatment of azole resistant strains of Af
Micro-analysis as a Tool for the Characterization of Historical Masonry Buildings: The Decorative Elements of the Basilica Della Beata Vergine Maria Del Rosario (Polesella, Rovigo)
No full textThe Basilica of the Beata Vergine Maria del Rosario of Polesella, the subject of this study, was built in the mid-eighteenth century in the village of Polesella (in the province of Rovigo, Veneto Region, Italy). Some restoration work on the Basilica has been necessary for recent years; this has allowed sampling of interior plasters on which preliminary microanalyses have been performed to better characterize the building materials used, in support of subsequent repair work. Among the many planned restoration works, interventions on the interior walls were, in addition, also planned. For this, the interior plasters and interior painting of the church were studied through observations with SEM–EDS. The objective of this work is mainly to show how archeometric analyses can be a valuable tool to improve the knowledge and characterization of the materials used, in this case, on some decorative elements of the Basilica. In particular, regarding the frescoes, the research was also aimed at identifying the type of pigments used by the author Luigi Battisti, believed to be the author of some of the works on display
In Vivo Efficacy of Voriconazole in a <i>Galleria mellonella</i> Model of Invasive Infection Due to Azole-Susceptible or Resistant <i>Aspergillus fumigatus</i> Isolates
No full textAspergillus fumigatus is an environmental filamentous fungus responsible for life-threatening infections in humans and animals. Azoles are the first-line treatment for aspergillosis, but in recent years, the emergence of azole resistance in A. fumigatus has changed treatment recommendations. The objective of this study was to evaluate the efficacy of voriconazole (VRZ) in a Galleria mellonella model of invasive infection due to azole-susceptible or azole-resistant A. fumigatus isolates. We also sought to describe the pharmacokinetics of VRZ in the G. mellonella model. G. mellonella larvae were infected with conidial suspensions of azole-susceptible and azole-resistant isolates of A. fumigatus. Mortality curves were used to calculate the lethal dose. Assessment of the efficacy of VRZ or amphotericin B (AMB) treatment was based on mortality in the lethal model and histopathologic lesions. The pharmacokinetics of VRZ were determined in larval hemolymph. Invasive fungal infection was obtained after conidial inoculation. A dose-dependent reduction in mortality was observed after antifungal treatment with AMB and VRZ. VRZ was more effective at treating larvae inoculated with azole-susceptible A. fumigatus isolates than larvae inoculated with azole-resistant isolates. The concentration of VRZ was maximal at the beginning of treatment and gradually decreased in the hemolymph to reach a Cmin (24 h) between 0.11 and 11.30 mg/L, depending on the dose. In conclusion, G. mellonella is a suitable model for testing the efficacy of antifungal agents against A. fumigatus
Airport malaria: report of four cases in Tunisia
No full textInternational audienceFour cases of airport malaria were notified for the first time in Tunisia during the summer of 2013. All patients were neighbours living within 2 km of Tunis International Airport. They had no history of travel to malarious countries, of blood transfusion or of intravenous drug use. Although malaria transmission had ceased in Tunisia since 1980, autochthonous infection by local Anopheles mosquitoes was initially considered. However, this diagnostic hypothesis was ruled out due to negative entomological survey and the absence of additional cases. All cases were caused by Plasmodium falciparum. Clinical presentation was severe (important thrombocytopaenia and parasitaemia), because of relatively important delay in diagnosis (average of seven days). This indicates the need to consider malaria while examining airport employees or people living near international airports presenting with fever of unknown origin. It also stresses the need for effective spraying of aircrafts coming from malarious areas
Image_1_In vitro and in vivo evaluation of antifungal combinations against azole-resistant Aspergillus fumigatus isolates.tif
No full textAzole resistance in Aspergillus fumigatus (Af) has become a widespread threat and a major concern for optimal management of patients with invasive aspergillosis (IA). Combination of echinocandins with azoles is an attractive alternative option for the treatment of IA due to azole-resistant Af strains. The aim of this study was to evaluate the in vitro and in vivo combination of caspofungin (CAS) with either voriconazole (VRZ) or posaconazole (PSZ). In vitro interactions were assessed by two methods, and an animal model of IA in Galleria mellonella was used for in vivo evaluation. Assessment of efficacy was based on larvae mortality. Groups of 10 larvae were infected by 3 clinical strains of Af (azole susceptible, AfS; PSZ resistant, AfR1; VRZ and PSZ resistant strain, AfR2). In vitro, combination of CAS and azoles was indifferent against AfS, and AfR2, and a synergy was found for AfR1. When compared to VRZ monotherapy, the combination of VRZ at 4 µg/larva with CAS at 4 µg/larva improved survival of AfR2-infected larvae (p=0.0066). Combination of PSZ at 4µg/larva with CAS at 4 µg/larva improved survival of AfR1-infected larvae compared to CAS (p=0.0002) and PSZ (0.0024) monotherapy. Antagonism was never observed. In conclusion, the combination of caspofungin with azoles is a promising alternative for the treatment of azole resistant strains of Af.</p
Image_2_In vitro and in vivo evaluation of antifungal combinations against azole-resistant Aspergillus fumigatus isolates.tif
No full textAzole resistance in Aspergillus fumigatus (Af) has become a widespread threat and a major concern for optimal management of patients with invasive aspergillosis (IA). Combination of echinocandins with azoles is an attractive alternative option for the treatment of IA due to azole-resistant Af strains. The aim of this study was to evaluate the in vitro and in vivo combination of caspofungin (CAS) with either voriconazole (VRZ) or posaconazole (PSZ). In vitro interactions were assessed by two methods, and an animal model of IA in Galleria mellonella was used for in vivo evaluation. Assessment of efficacy was based on larvae mortality. Groups of 10 larvae were infected by 3 clinical strains of Af (azole susceptible, AfS; PSZ resistant, AfR1; VRZ and PSZ resistant strain, AfR2). In vitro, combination of CAS and azoles was indifferent against AfS, and AfR2, and a synergy was found for AfR1. When compared to VRZ monotherapy, the combination of VRZ at 4 µg/larva with CAS at 4 µg/larva improved survival of AfR2-infected larvae (p=0.0066). Combination of PSZ at 4µg/larva with CAS at 4 µg/larva improved survival of AfR1-infected larvae compared to CAS (p=0.0002) and PSZ (0.0024) monotherapy. Antagonism was never observed. In conclusion, the combination of caspofungin with azoles is a promising alternative for the treatment of azole resistant strains of Af.</p
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