Lecture 14 Introduction to Medical Mycology (I& II) PDF

Microbiology & Immunology Unit Lecture 14 Introduction to Medical Mycology (I& II) Dr. Rasha Mokhtar Elnagar M.B.B.C, MSc, PhD, MD Medical Microbiology and Immunology Associate Professor of Medical Microbiology & Immunology Con...

Microbiology & Immunology Unit Lecture 14 Introduction to Medical Mycology (I& II) Dr. Rasha Mokhtar Elnagar M.B.B.C, MSc, PhD, MD Medical Microbiology and Immunology Associate Professor of Medical Microbiology & Immunology Consultant Microbiology & Immunology  Content of lecture  General properties and structure of Fungi  Morphology of Fungi  Classification of medically important fungi  Human mycosis Laboratory Diagnosis of Fungal Infections Specimens: According to the site of infection: skin scrapings, hairs, nails, respiratory secretions, blood, … Laboratory Diagnostic Tests: 1-Direct microscopic examination 2-Fungal culture 3-Serological tests 4-Skin tests 5-Molecular methods as PCR 1-Direct microscopic examination: A. Unstained preparations (wet mount): e.g., for Skin scraping, nails, or hairs add a drop of KOH (10-30%). KOH KOH -- preparation preparation B. Stained preparation by:  Lactophenol cotton blue (main stain).  Silver stain  Periodic acid Schiff (PAS) Aspergillus spp. Penicillium spp. 2. Fungal culture: All fungi are aerobic. Temperature requirement :  Majority of fungi : 25-27°C Superficial  Yeast: 37°C  Dimorphic fungi: 25°C & 37°C Incubation time:  Usually positive cultures are obtained in 7-10 days  At least 4 weeks  Candida & Aspergillus - 24 to 72 hrs. ungal culture Sabouraud`s dextrose agar (SDA): Enriched and selective media for fungi. Aspergillus niger Aspergillus flavus Mucor Penicillium spp. Candida albicans. 3-Serological tests: Antigens and antibodies detection β-D- Glucan detection in blood samples is diagnostic of invasive fungal infections. Galactomannan detection in blood samples is diagnostic for invasive aspergillosis. Detection of specific antibodies to diagnose systemic mycosis.  Antifungal therapy Mechanism of action: 1. Inhibit Cell wall synthesis: Caspofungin 2. Inhibit Ergosterol synthesis in cell membrane: o Polyenes: nystatin & amphotericin B o Azoles: miconazole &fluconazole 3. DNA synthesis inhibitors: Flucytosine Caspofungin Polyenes Flucytosine Azoles Q1: Which of these is a component of the cell membrane of fungi? A. Cholesterol B. Chitin C. Ergosterol D. Peptidoglycan Q2: Tinea pedis or (“Athlete’s foot) means: A. Fungal infection of scalp B. Fungal infection of toe web C. Fungal infection of non-bearded parts of the face D. Suppurative bacterial infection of scalp Q:Which of these antifungal agent inhibits the nucleic acid synthesis? A. Caspofungin B. Azoles C. Polyene D. Flucytosine Q:Which of the these is an example of yeast fungi? A. Histoplasma capsulatum B. Penicillium spp. D. Candida albicans E. Aspergillus flavus Reference Lippincott Illustrated Microbiology 4th edition, Chapters: 20.