University:
University of Alberta
Course:
MMI 133 | Medical Microbiology for Health Care Professionals
Academic year:

2024
Views:

127

Pages:

3
Author:

Ali O

Part 1: Fungi Lecture 7 Fungi 3 Types of Fungi: 1. Moulds 2. Yeasts 3. Thermally Dimorphic ↳ Mould at 20*C ↳ Yeast at 37*C · Nosocomial (hospital acquired) infections · Opportunistic infections of immunocompromised · Few are primary pathogens (mainly dimorphic moulds) · Cell walls are made of chitin ↳ chitin stains with calcofluor white · Ergosterol in cell membrane ↳ we target ergosterol in drugs because it stops them from being able to grow -Amphotericin B (most widely used) -Azoles -Nystatin 1. Moulds · made of long filaments called hyphae · the body of the fungus is called the thallus · reproduces through conidia spores Hyphae 2. Yeasts · oval or spherical shape · reproduce by budding · pseudohyphae form when the buds fail to detach from mother cell · yeasts use facultative anaerobic growth, most molds are anaerobic only 2. a) Candida Albicans · may attack to epithelial cells as a yeast, but invades deeper tissues by using pseudohyphae · C. Albicans is normal flora in the gut and mouth · can lead to candidiasis and thrush in newborns and immunocompromised (vaginal yeast infections) 2. b) Saccharomyces · yeast thats used for baking, wine, leavening dough · nonpathogenic 2. c) Cryptococcus neoformans · produces a polysaccharide capsule · can cause meningitis in immunocompromised (In bird poop - pigeon) 3. Thermally Dimorphic Fungi · can grow as a mold or yeast based on temperature ↳ mold 20* C, yeast 37* C · dimorphism: temperature dependent · the moulds are considered pathogenic · dimorphic fungi are NOT infections from one person to another, the mould form is spread by spores in the air Sporothrix (subcutaneous infection) · dimorphic · "Rose Gardener's Disease" · fungal spores introduced into wound after trauma (pricked by rose thorn) · Lymphangitis: inflammation of the walls of lymphatic vessels Fungal Reproduction · formation of spores called "conidia" ↳ conidia is used for identification and reproduction Fungal Nutrition · don't require as much nutrients, not picky either · grows better than bacteria in extreme conditions · most are aerobic and grow best at 25-30* C Fungal Diseases · all fungal diseases are called mycoses (plural) or mycosis (singular) Types of Mycoses: 1. Superficial 2. Cutaneous 3. Systemic Less severe 1. Superficial Mycoses Most severe outer layer of skin · mild infections · Fungal infection along surface of hair shafts and ↳ black and white piedra (hairs of scalp) ↳ Malassezia furfur: yeast on the surface of 2. Cutaneous Mycoses the skin that causes decolourization · Fungal infection of deeper layers of the epidermis ↳ eg. ) athletes foot, ringworm · caused by dermatophytes that degrade and use keratin as a carbon source · 3 different moulds with same method of pathogenicity · clinical diseases are called "tineas" 3. Systemic Mycoses · Infections in deep tissues (organs) · caused by primary pathogens such as dimorphic fungi OR opportunistic pathogens ↳ Candida albicans (the yeast listed above) ↳ Aspergillus species (causes aspergillosis when spore gets pushed into tissues)