Kévin Brunet

Candida auris is a multidrug-resistant fungal pathogen responsible for invasive nosocomial infections with high mortality rates. Recent detection of C. auris in natural environments suggests the existence of an environmental reservoir, prompting investigation into the potential role of azole fungicides used for plant protection in the development of resistance to antifungals used in human medicine. Here, we assessed the impact of azole fungicides on in vitro resistance development in two C. auris strains (B11220 and B11221) through sequential exposure to epoxiconazole, propiconazole, or tebuconazole. Exposure resulted in a rapid and significant increase in fungicide MICs, accompanied by a reduced susceptibility to four azole antifungals (fluconazole, voriconazole, posaconazole, isavuconazole), and to a new antifungal agent, the manogepix. Several strains with elevated MICs exhibited stable phenotypes and were associated with a mutation in the TAC1B gene. One of these strains showed a significant overexpression of the efflux pump CDR1. These findings provide experimental evidence that azole fungicides can drive resistance to azole antifungals and reduce susceptibility to manogepix, underscoring the need for integrated One Health antifungal stewardship strategies to combat C. auris.

La mucormycose pulmonaire est une infection fongique invasive grave affectant les patients immunodéprimés. Le traitement de référence fait appel à l’amphotéricine B (AmB) liposomale mais reste peu efficace avec environ 50% de mortalité malgré celui-ci. Le but de cette thèse était d’optimiser le traitement préventif et curatif de la mucormycose pulmonaire. Pour cela, cette thèse a été structurée en 2 axes, un axe préventif puis un axe curatif, eux-mêmes divisés en deux sous-parties.La première partie de l’axe « préventif » s’intéressait au phénomène de réactivation des infections fongiques invasives. Ce concept a été décrit dans un premier article. Son postulat est le suivant : suite à une primo-infection asymptomatique, une seconde infection peut se produire à distance à la faveur d’une immunodépression. Un modèle murin a été développé pour reproduire ce concept et évaluer l’intérêt de l’AmB en décolonisation pour prévenir ce phénomène de réactivation. L’AmB en décolonisation s’est révélé efficace pour prévenir la survenue de la maladie.La seconde partie de cet axe avait pour but d’étudier le rôle des corticoïdes dans la physiopathologie de l’infection. Pour ce faire, un modèle ex vivo qui consiste à administrer des corticoïdes à des souris, puis à récupérer les cellules pulmonaires par lavage broncho-alvéolaire a été mis au point. Les perturbations induites par les corticoïdes sur les cellules immunitaires ont ensuite été étudiées in vitro. Les corticoïdes ont diminué la capacité globale des macrophages alvéolaires à inhiber la filamentation du champignon, diminué la capacité de phagocytose des macrophages alvéolaires et leur capacité de « killing » oxydatif.La première partie de l’axe « curatif » a consisté à développer un modèle murin de mucormycose pulmonaire aigüe afin d’étudier la physiopathologie de cette infection. Ce modèle a été caractérisé sur les plans histologiques et immunitaires et permettra d’explorer la relation champignon-hôte-antifongique. La seconde partie de cet axe a permis d’évaluer in vitro des associations entre AmB et diverses molécules afin d’améliorer l’efficacité de l’AmB. Ces combinaisons ont été testées par technique de chequerboard sur différentes souches de Mucorales. Après avoir passé au crible 20 candidats (antibiotiques, antifongiques, alcools terpéniques, tensioactifs), un a été identifié, le PEG15HS, qui permet de diminuer les concentrations minimales inhibitrices d’AmB

Blastobotrys allociferrii is a yeast involved in human infection and colonization. Here, we present the first draft genome of B. allociferrii, which has been isolated from a human sample (CBS 18616).

Background: Data on the risk of invasive fungal infections (IFI) with ibrutinib treatment are scarce.Objectives: This study aimed to determine IFI incidence and risk factors in ibrutinib‐treated patients in real‐life settings.Methods: We constituted a cohort of ibrutinib incident users in the French National Healthcare Database. All patients ≥18 years with a first dispensing of ibrutinib between 21 November 2014 and 31 December 2019 were included. Patients were followed from the cohort entry date until IFI, ibrutinib discontinuation, death, or 31 December 2020, whichever came first. The cumulative incidence function method was used to estimate the probability of IFI accounting for competing risk of death. A multivariate cause‐specific Cox proportional hazards model was used to assess independent IFI risk factors.Results: Among 6937 ibrutinib‐treated patients, 1‐year IFI cumulative incidence was 1.3%, with invasive aspergillosis being the most frequent. Allogenic or autologous stem cell transplantation (ASCT) (hazard ratio [HR] 3.59, 95% confidence interval [1.74; 7.41]), previous anticancer treatment (HR 2.12, CI 95% [1.34; 3.35]) and chronic respiratory disease (HR 1.66, [1.03; 2.67]) were associated with higher risk of IFI. Besides neutropenia and corticosteroids, use of anti‐CD20 agents was significantly more frequent in patients having experienced IFI (HR 3.68, [1.82; 7.45]).Conclusions: In addition to patients with ASCT history, severe neutropenia or treated with corticosteroids, our findings support active surveillance of IFIs in those with chronic respiratory disease, previously treated, or treated with anti‐CD20 agents in combination with ibrutinib. Further studies are needed to optimise IFI prophylaxis in these patient subgroups.

Rhinocladiella similis is a melanized fungi involved in chromoblastomycosis. R. similis genome has never been sequenced, therefore we propose the first draft genome of R. similis.

Kazachstania bovina is a yeast species from the K. telluris complex that has been recently involved in bloodstream infections. While yeast genomes from this complex have already been sequenced, K. bovina genome has not been published yet. Here is the first draft genome of K. bovina (CBS 16326).

Few antifungal agents are currently available for the treatment of fungal infections. Antimicrobial peptides (AMPs), which are natural molecules involved in the innate immune response of many organisms, represent a promising research method because of their broad killing activity. The aim of this study was to assess the activity of a frog AMP, [K³]temporin-SHa, against some species of yeasts and moulds, and to further explore its activity against Candida albicans. MIC determinations were performed according to EUCAST guidelines. Next, the activity of [K³]temporin-SHa against C. albicans was explored using time-killing curve experiments, membrane permeabilization assays, and electron microscopy. Finally, chequerboard assays were performed to evaluate the synergy between [K³]temporin-SHa and amphotericin B or fluconazole. [K³]temporin-SHa was found to be active in vitro against several yeasts with MIC between 5.5 and 45 µM. [K³]temporin-SHa displayed rapid fungicidal activity against C. albicans (inoculum was divided into two in less than an hour and no viable colonies were recovered after 5 h) with a mechanism that could be due to membrane permeabilization. [K³]temporin-SHa was synergistic with amphotericin B against C. albicans (FICI = 0.303). [K³]temporin-SHa could represent an additional tool to treat several Candida species and C. neoformans.

Pulmonary mold infections are life-threatening diseases with high morbi-mortalities. Treatment is based on systemic antifungal agents belonging to the families of polyenes (amphotericin B) and triazoles. Despite this treatment, mortality remains high and the doses of systemic antifungals cannot be increased as they often lead to toxicity. The pulmonary aerosolization of antifungal agents can theoretically increase their concentration at the infectious site, which could improve their efficacy while limiting their systemic exposure and toxicity. However, clinical experience is poor and thus inhaled agent utilization remains unclear in term of indications, drugs, and devices. This comprehensive literature review aims to describe the pharmacokinetic behavior and the efficacy of inhaled antifungal drugs as prophylaxes and curative treatments both in animal models and humans.

The aim of this study was to evaluate the effect of the combination of amphotericin B (AmB) and various non-ionic surfactants on the anti-Mucorales activity of AmB, the toxicity of the combination on eukaryotic cells and the modification of AmB aggregation states. Checkerboards were performed on five genera of Mucorales (12 strains) using several combinations of different surfactants and AmB. These data were analyzed by an E_max model. The effect of surfactants on the cytotoxic activity of AmB was then evaluated for red blood cells and two eukaryotic cell lines by absorbance and propidium iodide internalization. Finally, the effect of polyethylene glycol (15)-hydroxystearate (PEG15HS) on the aggregation states of AmB was evaluated by UV-visible spectrometry. PEG15HS increased the efficacy of AmB on four of the five Mucorales genera, and MICs of AmB were decreased up to 68-fold for L. ramosa. PEG15HS was the only surfactant to not increase the cytotoxic activity of AmB. Finally, the analysis of AmB aggregation states showed that the increased efficacy of AmB and the absence of toxicity are related to an increase in monomeric and polyaggregated forms of AmB at the detriment of the dimeric form. In conclusion, PEG15HS increases the in vitro efficacy of AmB against Mucorales at low concentration, without increasing its toxicity; this combination could therefore be evaluated in the treatment of mucormycosis.