Full text loading...
Chapter 29 : Zygomycetes as Agents of Infectious Disease in Humans
Category: Fungi and Fungal Pathogenesis
Ebook: Choose a downloadable PDF or ePub file. Chapter is a downloadable PDF file. File must be downloaded within 48 hours of purchase
The zygomycoses are a group of infections caused by a variety of fungal organisms belonging to the class Zygomycetes. This class is composed of two orders, Mucorales and Entomophthorales. The focus of this chapter is to discuss the molecular principles of mucormycosis pathogenesis. The agents of mucormycosis are classified into six different families based on morphologic analysis of the fungus, carbohydrate assimilation, and the maximal growth temperature. Of note, these categories of invasive mucormycosis tend to occur in patients with specific defects in host defense. The mechanism by which ketoacidosis enhances susceptibility to rhinocerebral disease remains unclear. As discussed, patients in ketoacidosis, or indeed those with any systemic acidosis, have increased available serum iron due to proton-mediated dissociation of iron from sequestering proteins. Simulated acidotic conditions decreased the iron-binding capacity of sera collected from normal volunteers. Importantly, rFTR1 gene expression is induced when R. oryzae is iron limited, indicating that this gene might operate in vivo where the iron supply is limited. The amdS gene allows the organism to grow on media containing acetamide as a sole source of nitrogen. These molecular approaches will aid in understanding mucormycosis pathogenesis and may therefore contribute to establishing improved therapeutic strategies to treat and/or prevent mucormycosis infections. Genome sequence data have the potential to revolutionize the study of mucormycosis, as has been done for other pathogenic fungi, including Candida and Aspergillus. A recently completed genome sequence project can provide data in advancing our understanding of the pathogenesis of mucormycosis.
Key Concept Ranking
- Antifungal Agents
Taxonomy of Zygomycetes. Adapted from reference 84 .