Gut microbiome in BALB/c and C57BL/6J mice undergoing experimental thyroid autoimmunity associate with differences in immunological responses and thyroid function

Experimental models of hyperthyroid Graves’ disease (GD) and Graves’ orbitopathy (GO) are efficiently developed by genetic immunisation by electroporation with human thyrotropin hormone receptor (hTSHR) A-subunit plasmid in female BALB/c (H-2d) mice. We investigated susceptibility in C57BL/6 J (H-2b) animals to allow studies on disease mechanisms in transgenic and immune response gene knock-out mice. Higher numbers of female C57BL/6 J were positive for pathogenic thyroid stimulating antibodies, but induced hyperthyroidism remained at a low frequency compared to BALB/c animals. Assessment of hTSHR specific T cells showed reduced proliferation in C57BL/6 J animals accompanied with anti-inflammatory IL-10, with less pro-inflammatory IFN-γ compared to BALB/c. Whilst the orbital tissue from immune BALB/c mice showed inflammation and adipogenesis, in contrast C57BL/6 J animals showed normal pathology. We characterised the gut microbiota using 16 S ribosomal RNA gene sequencing to explore its possible pathogenic role in the model. Despite being housed under identical conditions, we observed significantly different organisation of the microbiota (beta-diversity) in the two strains. Taxonomic differences were also noted, with C57BL/6 J showing an enrichment of Operational Taxonomic Units (OTUs) belonging to the Paludibacter and Allobaculum, followed by Limibacter, Anaerophaga and Ureaplasma genera. A higher number of genera significantly correlating with clinical features was observed in C57BL/6 J compared to BALB/c; for example, Limibacter OTUs correlated negatively with thyroid-stimulating antibodies in C57BL/6 J mice. Thus, our data suggest gut microbiota may play a pivotal immunomodulatory role that differentiates the thyroid function and orbital pathology outcome in these two inbred strains undergoing experimental GO

Microbiological Non-Culture-Based Methods for Diagnosing Invasive Pulmonary Aspergillosis in ICU Patients

The diagnosis of invasive pulmonary aspergillosis (IPA) in intensive care unit (ICU) patients is crucial since most clinical signs are not specific to invasive fungal infections. To detect an IPA, different criteria should be considered. Next to host factors and radiological signs, microbiological criteria should be fulfilled. For microbiological diagnostics, different methods are available. Next to the conventional culture-based approaches like staining and culture, non-culture-based methods can increase sensitivity and improve time-to-result. Besides fungal biomarkers, like galactomannan and (1→3)-β-D-glucan as nonspecific tools, molecular-based methods can also offer detection of resistance determinants. The detection of novel biomarkers or targets is promising. In this review, we evaluate and discuss the value of non-culture-based microbiological methods (galactomannan, (1→3)-β-D-glucan, Aspergillus PCR, new biomarker/targets) for diagnosing IPA in ICU patients

Antibacterial Activity of the Novel Drug Gepotidacin against <i>Stenotrophomonas maltophilia</i>—An In Vitro and In Vivo Study

Stenotrophomonas maltophilia is increasingly recognized as a nosocomial bacterial pathogen with a multi-drug resistance profile. In this study, the novel drug gepotidacin, the first compound of the novel triazaacenaphthylene topoisomerase inhibitor antibiotics class, was evaluated on its activity against clinical S. maltophilia isolates. Ninety-nine S. maltophilia isolates plus reference strain K279a (N = 100) were tested on their susceptibility towards gepotidacin in a broth microdilution. Additional susceptibility testing was performed towards the commonly applied combination trimethoprim/sulfamethoxazole (TMP/SXT), moxifloxacin, and levofloxacin. The time–kill kinetic of gepotidacin was observed in a time–kill assay. The greater wax moth Galleria mellonella was used to determine the activity of gepotidacin against S. maltophilia in vivo. Gepotidacin showed minimum inhibitory concentrations (MICs) between 0.25 and 16 mg/L (MIC50: 2 mg/L; MIC90: 8 mg/L), independently of its susceptibility towards TMP/SXT. The five TMP/SXT resistant strains exhibited gepotidacin MICs from 1 to 4 mg/L. The S. maltophilia strains resistant to the assessed fluoroquinolones showed in parts high MICs of gepotidacin. The time–kill assay revealed a time- and strain-dependent killing effect of gepotidacin. In vivo, injection of gepotidacin increased the survival rate of the larvae from 61 % to 90 % after 2 days. This study showed antimicrobial effects of gepotidacin towards S. maltophilia

Prevalence of COVID-19 Associated Mucormycosis in a German Tertiary Care Hospital

Due to Coronavirus disease (COVID-19) a new group of patients at risk emerged with COVID-19-associated mucormycosis (CAM). Systematic studies, evaluating the prevalence of CAM are missing. To assess CAM prevalence in a tertiary care hospital in Germany, we applied direct microscopy, fungal culture and quantitative realtime in-house PCR targeting Mucorales-specific fragments of 18S and 28S rRNA on respiratory specimens of 100 critically ill COVID-19 patients. Overall, one Mucorales-PCR positive bronchoalevolar lavage was found whereas direct microscopy and fungal culture were negative in all cases. We conclude that a routine screening for CAM in Germany is not indicated

Reduced Sphingosine in Cystic Fibrosis Increases Susceptibility to <i>Mycobacterium abscessus</i> Infections

Cystic fibrosis (CF) is an autosomal recessive disorder caused by the deficiency of the cystic fibrosis transmembrane conductance regulator (CFTR) and often leads to pulmonary infections caused by various pathogens, including Staphylococcus aureus, Pseudomonas aeruginosa, and nontuberculous mycobacteria, particularly Mycobacterium abscessus. Unfortunately, M. abscessus infections are increasing in prevalence and are associated with the rapid deterioration of CF patients. The treatment options for M. abscessus infections are limited, requiring the urgent need to comprehend infectious pathogenesis and develop new therapeutic interventions targeting affected CF patients. Here, we show that the deficiency of CFTR reduces sphingosine levels in bronchial and alveolar epithelial cells and macrophages from CF mice and humans. Decreased sphingosine contributes to the susceptibility of CF tissues to M. abscessus infection, resulting in a higher incidence of infections in CF mice. Notably, treatment of M. abscessus with sphingosine demonstrated potent bactericidal activity against the pathogen. Most importantly, restoration of sphingosine levels in CF cells, whether human or mouse, and in the lungs of CF mice, provided protection against M. abscessus infections. Our findings demonstrate that pulmonary sphingosine levels are important in controlling M. abscessus infection. These results offer a promising therapeutic avenue for CF patients with pulmonary M. abscessus infections

Effect of Dexamethasone on the Incidence and Outcome of COVID-19 Associated Pulmonary Aspergillosis (CAPA) in Critically Ill Patients during First- and Second Pandemic Wave&mdash;A Single Center Experience

Superinfections with Aspergillus spp. in patients with Coronavirus disease 2019 (CAPA: COVID-19-associated pulmonary aspergillosis) are increasing. Dexamethasone has shown beneficial effects in critically ill COVID-19 patients. Whether dexamethasone increases the risk of CAPA has not been studied exclusively. Moreover, this retrospective study aimed to identify risk factors for a worse outcome in critically ill COVID-19 patients. Data from 231 critically ill COVID-19 patients with or without dexamethasone treatment from March 2020 and March 2021 were retrospectively analysed. Only 4/169 (6.5%) in the DEXA-group and 13/62 (7.7%) in the Non-DEXA group were diagnosed with probable CAPA (p = 0.749). Accordingly, dexamethasone was not identified as a risk factor for CAPA. Moreover, CAPA was not identified as an independent risk factor for death in multivariable analysis (p = 0.361). In contrast, elevated disease severity (as assessed by Sequential Organ Failure Assessment [SOFA]-score) and the need for organ support (kidney replacement therapy and extracorporeal membrane oxygenation [ECMO]) were significantly associated with a worse outcome. Therefore, COVID-19 treatment with dexamethasone did not increase the risk for CAPA. Moreover, adequately treated CAPA did not represent an independent risk factor for mortality. Accordingly, CAPA might reflect patients&rsquo; severe disease state instead of directly influencing outcome

Comparison of genotyping methods for Cunninghamella bertholletiae

Background Invasive fungal infections caused by filamentous fungi of the order Mucorales are serious complications in immunocompromised patients and often associated with fatal outcome. As a member of this order, Cunninghamella bertholletiae is a saprophytic fungus with naturally exhibited high minimum inhibitory concentrations against common antifungal drugs and with the potential for outbreaks in clinical settings. Objectives and methods In a proof-of-principle study, we evaluated the performance of microsatellite markers for the discrimination of thirteen C. bertholletiae isolates from various sources in comparison with a repetitive sequence-based PCR (rep-PCR) and random amplification of polymorphic DNA (RAPD). Based on the higher discriminatory power of the microsatellite PCR with five separate primer pairs (Simpson's index of 1 vs 0 [RAPD] and 0 [rep-PCR]), the novel method was applied to eight additional isolates, including four well-characterised isolates from a cluster of infections in a next step. Results In total, microsatellite PCR identified 21 separate genotypes. A probable epidemiological association of the cluster isolates could be demonstrated by microsatellite genotyping. Conclusion In conclusion, our findings demonstrate the value of microsatellite PCR in genotyping Cunninghamella bertholletiae and its potential for future applications with other species of the order Mucorales

Gut microbiome associated with Graves disease and Graves orbitopathy: the INDIGO Multicenter European Study

Context Gut bacteria can influence host immune responses but little is known about their role in tolerance-loss mechanisms in Graves disease (GD; hyperthyroidism caused by autoantibodies, TRAb, to the thyrotropin receptor, TSHR) and its progression to Graves orbitopathy (GO). Objective This work aimed to compare the fecal microbiota in GD patients, with GO of varying severity, and healthy controls (HCs). Methods Patients were recruited from 4 European countries (105 GD patients, 41 HCs) for an observational study with cross-sectional and longitudinal components. Results At recruitment, when patients were hyperthyroid and TRAb positive, Actinobacteria were significantly increased and Bacteroidetes significantly decreased in GD/GO compared with HCs. The Firmicutes to Bacteroidetes (F:B) ratio was significantly higher in GD/GO than in HCs. Differential abundance of 15 genera was observed in patients, being most skewed in mild GO. Bacteroides displayed positive and negative correlations with TSH and free thyroxine, respectively, and was also significantly associated with smoking in GO; smoking is a risk factor for GO but not GD. Longitudinal analyses revealed that the presence of certain bacteria (Clostridiales) at diagnosis correlated with the persistence of TRAb more than 200 days after commencing antithyroid drug treatment. Conclusion The increased F:B ratio observed in GD/GO mirrors our finding in a murine model comparing TSHR-immunized with control mice. We defined a microbiome signature and identified changes associated with autoimmunity as distinct from those due to hyperthyroidism. Persistence of TRAb is predictive of relapse; identification of these patients at diagnosis, via their microbiome, could improve management with potential to eradicate Clostridiales