Post-influenzal triazole-resistant aspergillosis following allogeneic stem cell transplantation

Pathogenesis of Respiratory Viral and Fungal Coinfections

Individuals suffering from severe viral respiratory tract infections have recently emerged as "at risk" groups for developing invasive fungal infections. Influenza virus is one of the most common causes of acute lower respiratory tract infections worldwide. Fungal infections complicating influenza pneumonia are associated with increased disease severity and mortality, with invasive pulmonary aspergillosis being the most common manifestation. Strikingly, similar observations have been made during the current coronavirus disease 2019 (COVID-19) pandemic. The copathogenesis of respiratory viral and fungal coinfections is complex and involves a dynamic interplay between the host immune defenses and the virulence of the microbes involved that often results in failure to return to homeostasis. In this review, we discuss the main mechanisms underlying susceptibility to invasive fungal disease following respiratory viral infections. A comprehensive understanding of these interactions will aid the development of therapeutic modalities against newly identified targets to prevent and treat these emerging coinfections.

Influenza-Associated Aspergillosis: Nationwide Trends, Predictors and Outcomes From 2005 to 2014

BACKGROUND

Influenza-associated aspergillosis (IAA) has been increasingly reported in the literature in recent years, but contemporary large-scale data on the morbidity and mortality burden of IAA are lacking.

RESEARCH QUESTION

The goal of this study was to estimate the predictors, associations, and outcomes of IAA in the United States.

STUDY DESIGN AND METHODS

This retrospective cohort study was performed by using the National (Nationwide) Inpatient Sample database from 2005 to 2014 to identify influenza and IAA hospitalizations. Baseline variables and outcomes were compared between influenza hospitalizations without IAA and those with IAA. These variables were then used to perform an adjusted analysis for obtaining predictors and associations of the diagnosis and in-hospital mortality of IAA.

RESULTS

Of the 477,556 hospitalizations identified with the principal diagnosis of influenza, IAA was identified in 823 (0.17%) hospitalizations. The IAA cohort consisted more commonly of 45- to 65-year-olds in urban teaching hospitals with substance abuse. Yearly trends revealed that both influenza and IAA hospitalizations have increased over time, with a peak observed in 2009, the year of the influenza A(H1N1) pandemic. Mortality was higher (20.58% vs 1.36%), average length of stay was longer (17.94 vs 4.05 days), and mean cost per hospitalization was higher ($194,932 vs $24,286) in the IAA cohort compared with the influenza cohort without IAA (P < .005). Solid-organ transplantation, hematologic malignancies, and use of invasive mechanical ventilation were associated with higher odds of IAA, among other factors. Use of invasive mechanical ventilation (adjusted OR, 13.43; P < .005), longer length of stay (adjusted OR, 5.47; P < .005), utilization of extracorporeal membrane oxygenation (adjusted OR, 4.99; P = .014), and the group aged 45 to 64 years (adjusted OR, 3.03; P = .012) were associated with higher in-hospital mortality in the IAA cohort.

INTERPRETATION

Although IAA is a rare complication of influenza hospitalizations, it is associated with increased all-cause mortality, more extended hospital stays, and higher hospital charges compared with influenza without IAA.

Azole-Resistant COVID-19-Associated Pulmonary Aspergillosis in an Immunocompetent Host: A Case Report

COVID-19-associated pulmonary aspergillosis (CAPA) is a recently described disease entity affecting patients with severe pulmonary abnormalities treated in intensive care units. Delays in diagnosis contribute to a delayed start of antifungal therapy. In addition, the emergence of resistance to triazole antifungal agents puts emphasis on early surveillance for azole-resistant Aspergillus species. We present a patient with putative CAPA due to Aspergillus fumigatus with identification of a triazole-resistant isolate during therapy. We underline the challenges faced in the management of these cases, the importance of early diagnosis and need for surveillance given the emergence of triazole resistance.

Revealing the Virulence Potential of Clinical and Environmental Aspergillus fumigatus Isolates Using Whole-Genome Sequencing

Aspergillus fumigatus is considered a common causative agent of human fungal infections. A restricted number of virulence factors have been described, and none of them lead to a differentiation in the virulence level among different strains. Variations in the virulence phenotype depending on the isolate origin, measured as survival percentage in animal infection models, have been previously reported. In this study, we analyzed the whole-genome sequence of A. fumigatus isolates from clinical and environmental origins to determine their virulence genetic content. The sample included four isolates sequenced at the University Medical Center Groningen (UMCG), three clinical (two of them isolated from the same patient) and the experimental strain B5233, and the draft genomes of one reference strain, two environmental and two clinical isolates obtained from a public database. The fungal genomes were screened for the presence of virulence-related genes (VRGs) using an in-house database of 244 genes related to thermotolerance, resistance to immune responses, cell wall formation, nutrient uptake, signaling and regulation, and production of toxins and secondary metabolites and allergens. In addition, we performed a variant calling analysis to compare the isolates sequenced at the UMCG and investigated their genetic relatedness using the TRESP (Tandem Repeats located within Exons of Surface Protein coding genes) genotyping method. We neither observed a difference in the virulence genetic content between the clinical isolates causing an invasive infection and a colonizing clinical isolate nor between isolates from the clinical and environmental origin. The four novel A. fumigatus sequences had a different TRESP genotype and a total number of genetic variants ranging from 48,590 to 68,352. In addition, a comparative genomics analysis showed the presence of single nucleotide polymorphisms in VRGs and repetitive genetic elements located next to VRG groups, which could influence the regulation of these genes. In conclusion, our genomic analysis revealed a high genetic diversity between environmental and clinical A. fumigatus isolates, as well as between clinical isolates from the same patient, indicating an infection with a mixed-population in the latter case. However, all isolates had a similar virulence genetic content, demonstrating their pathogenic potential at least at the genomic level.