Chapter 7 Fungal Classification, Structure, and Replication Medical Microbiology Chapter 7 Fungal Classification, Structure, and Replication

Importance of Fungi Fungi are ubiquitous and diverse They have recently emerged as significant pathogens Especially among immunocompromised and hospitalized individuals Table 7-1 According to your book, “there are no nonpathogenic fungi!”

Fungi Fungi are eukaryotic cells Problem with treatment? They contain a rigid cell wall made of chitin and glucan They also have ergosterol in their membranes Figure 7-1

Fungi Morphologies: Yeasts – single-celled organisms Replication by budding or fission May produce pseudohyphae Produce colonies on agar Molds – multicellular organisms Consist of hyphae that form a mat-like structure called a mycelium Dimorphic Fungi – can be found as either yeasts or molds Figures 7-2 and 7-3

Human Mycoses Mycosis – infection caused by a fungus Superficial mycoses – limited to very superficial surfaces of skin and hair Of cosmetic importance only Figures 72-3 and 72-5 Cutaneous mycoses – infections of the skin, hair, and nails Signs and symptoms – itching, scaling, broken hairs, ring-like patch on the skin, thickened, discolored nails. Caused by “dermatophytes” Figures 72-14, 72-15, and 72-16

Human Mycoses Subcutaneous mycoses – infections of the deeper tissues Can cause abscesses and non-healing ulcers Figures 73-1, 73-5, 73-8, and 73-9 Endemic Mycoses – systemic infections Fungi exhibit thermal dimorphism Can infect healthy individuals Generally confined to specific areas Figures 74-2, 74-5, 74-6, 74-12, and 74-14

Human Mycoses Opportunistic Mycoses – normally non-pathogenic fungi Candida spp. – thrush, vaginal yeast infections, other more serious infections Cryptococcus neoformans – pulmonary and CNS infections Figure 75-10 Aspergillus spp. others

Disease of the Day “The Terminator” article

Summary Summary – page 73