MICR J210 1st Edition Lecture 12Outline of Last Lecture First lecture for the examOutline of Current Lecture I. An overview of Medical MycologyII. Systemic Mycoses Caused by Pathogenic FungiIII. Superficial, Cutaneous, and Subcutaneous MycosesIV. Fungal Intoxications and AllergiesV. Classification of parasitesCurrent LectureAn Overview of Medical Mycology• Concerned with diagnosis, management, and prevention of fungal diseases or mycoses• Mycoses are among the most difficult diseases to diagnose and treat– Signs of mycoses are often missed or misinterpreted– Not typically screened for– Fungi are often resistant to antifungal agents– We don’t have good complement drugs to treat them– They are similar to our cells• The Epidemiology of Mycoses– Fungi and their spores are almost everywhere in the environment– Most people will experience a mycosis at some time– Typically acquired via inhalation, trauma, or ingestion– Infrequently spread from person to person – Not an infectious disease; usually picked up from the environment– Most mycoses are not contagious– Dermatophytes are the major exception• Fungi that can infect skin and are contagious (athlete’s foot)– Epidemics result from mass exposure to environmental source of fungi– Mycoses are generally not reportable– Adequate information on their occurrence is often lacking• Categories of Fungal Agents: True Fungal Pathogens and Opportunistic Fungi– Only four fungi usually considered true pathogens– Endemic to the Americans and other regions– Other fungi are opportunistic – Certain factors increase risk for opportunistic mycosesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.• Invasive medical procedure• Medical therapies• Certain disease conditions• Immunosuppression• Specific lifestyle factors• Clinical Manifestations of Fungal Diseases– Three categories of clinical manifestation– Fungal infections• Causes a growth on or in an individual• Most common mycoses• Caused by presence of true pathogens or opportunists– Toxicoses• Acquired through ingestion• Occurs when poisonous mushrooms are eaten– Allergies• Most often result from the inhalation of fungal spores• Fungal spores are allergen and can induce the production of IgE such as mold spores• The Diagnosis of Fungal Infections– Patient’s history is critical for diagnosis of most mycoses– Definitive diagnosis often requires morphological analysis of the fungus involved– Sabouraud dextrose agar used to culture fungi• This medium favors fungal growth– Various techniques used to detect fungal cells in patient specimens– Difficult to distinguish fungal infections from simple exposures– Opportunistic infections especially challenging– Difficult to identify what is causes the infection• Antifungal Therapies– Mycoses are among the most difficult diseases to heal: fungi are eukaryotes and we have very similar structures so many antifungal medications can have really harsh side effects– Fungi often resist T cell-mediated immune responses– Fungi biochemically similar to human cells• Antifungal drugs can harm human tissues • Ergosterol is often a target of antifungal drugs• Humans do not produce ergosterol– Amphotericin B is gold standard of antifungals (Amphoterrible)– Some cross reactivity with our own cells– Opportunistic infections require two-step treatment– High-dose treatment to reduce pathogens– Low-dose maintenance therapy– Azole drugs• Antifungal Vaccines– Antifungal vaccines have been difficult to develop– Not commonly used – Fungal metabolism similar to our own– Scientists have developed vaccines against some fungi– Coccidioides– Candida– Blastomycosis– These vaccines are primarily for people that are at risk…not the general exposureSystemic Mycoses Caused by Pathogenic Fungi• Infections spread throughout the body—not opportunistic or localized• Caused by one of four pathogenic fungi of the division Ascomycota– Blastomyces, Coccidioides, Histoplasma, and Paracoccidioides• Acquired through inhalation– Begins as generalized pulmonary infection – Disseminates via the blood to the rest of the body– Get them from the environment NOT other humans• All are dimorphic– have different manifestations in environment and host– Form mycelium: hypha and sporalating bodies – Can undergo sexual reproduction when less than 30 C and budding yeast cells in 37 C (human body temperature)• Individuals working with these fungi must take precautions to avoid exposure to spores• Histoplasmosis– Histoplasma capsulatum is the causative agent– Most common true fungal pathogen affecting humans– Mostly in the eastern United States but also in Africa and Asia– Fungi found in moist soils containing high nitrogen levels– Most common infection route is inhalation of spores into the lungs – H. capsulatum is phagocytosed by alveolar macrophages– Dispersed beyond the lungs via the blood and lymph– Macrophages are the ones that spread the disease– Usually asymptomatic and resolves without damage to lungs– Clinical histoplasmosis results in one of four diseases– Chronic pulmonary histoplasmosis: chronic growth of fungus in lung– Chronic cutaneous histoplasmosis: chronic growth of fungus in skin– Systemic histoplasmosis: chronic growth of fungus in the blood– Ocular histoplasmosis: chronic growth of fungus in eye– Infections in healthy individuals resolve on their own– Amphotericin B is preferred drug for those who require treatment• Blastomycosis– Blastomyces dermatitidis is the causative agent– Endemic in the southeastern United States north to Canada– Fungi found in soils rich in organic matter– Pulmonary blastomycosis is the most common manifestation– Initial pulmonary lesions are mostly asymptomatic– The disease resolves in most people but may become chronic if you have a weakened immune system– Other conditions may result– Cutaneous blastomycosis, osteoarticular blastomycosis, meningitis• Coccidioidomycosis– Also known as “Valley Fever”– Coccidioides immitis is the causative agent– Almost exclusively in the southwestern United States and Northern Mexico: not found inIN– Fungi in desert soil, rodent burrows, archaeological remains, mines– If inhaled, forms