Abstract

Biofilm formation during infections with the opportunistic pathogen Aspergillus fumigatus can be very problematic in clinical settings, since it provides the fungal cells with a protective environment. Resistance against drug treatments, immune recognition as well as adaptation to the host environment allows fungal survival in the host. The exact molecular mechanisms behind most processes in the formation of biofilms are unclear. In general, the formation of biofilms can be categorized roughly in a few stages; adhesion, conidial germination and development of hyphae, biofilm maturation and cell dispersion. Fungi in biofilms can adapt to the in-host environment. These adaptations can occur on a level of phenotypic plasticity via gene regulation. However, also more substantial genetic changes of the genome can result in increased resistance and adaptation in the host, enhancing the survival chances of fungi in biofilms. Most research has focused on the development of biofilms. However, to tackle developing microbial resistance and adaptation in biofilms, more insight in mechanisms behind genetic adaptations is required to predict which defense mechanisms can be expected. This can be helpful in the development of novel and more targeted antifungal treatments to combat fungal infections.

Highlights

  • Aspergillus fumigatus (A. fumigatus) is a saprophytic fungus that can normally be found in the soil, where it lives on organic debris

  • This study showed that the outer layer of the conidia was characterized by a layer of rodlets made of hydrophobins, a family of small hydrophobic proteins on the cell surface [21]

  • The results of this study indicated that the mixture of variants of A. fumigatus found at the sino-nasal mucosal surface in the dog is a result of in-host adaptation

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Summary

Introduction

Aspergillus fumigatus (A. fumigatus) is a saprophytic fungus that can normally be found in the soil, where it lives on organic debris. A. fumigatus can cause infections in the respiratory tract of immunocompromised individuals, such as patients following chemotherapy, receiving transplants and immunesuppressive drugs or those in intensive care [4,5]. Developments in medical therapy and technology such as organ transplantations accompanied with immunosuppression and new chemotherapeutic agents have increased the survival of patients suffering from severe diseases that previously would be fatal. Due to these advances in medical technology, the number of immunocompromised patients that are vulnerable to nosocomial infections by fungi has increased [7]. The mechanism and effect of genetic adaptation and micro-evolution in A. fumigatus biofilms will be described

Stages of Biofilm Development and Molecular Pathways
Adhesion
Conidial Germination and Hyphal Development
Biofilm Maturation
Cell Dispersion
Drug Resistance Mechanisms
Interaction with Host Immune Systems
Genetic Evolution and Adaptation
Primary and Acquired Resistance Mechanisms
Phenotypic Plasticity
Genomic Plasticity
Hypermutation
Transcriptomic Studies of Biofilms
Objective
Findings
Conclusions and Future Directions
Full Text
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