Medical Mycology PDF

**Medical Mycology** **Chapter overview** - Basic concepts in Mycology - Fungal Infections - Fungal allergies - Antifungal treatments **Mycology is the study of the Fungi** - Genetic and biochemical properties - Taxonomy - Use to humans as source for medicines (penicillin), fo...

**Medical Mycology** **Chapter overview** - Basic concepts in Mycology - Fungal Infections - Fungal allergies - Antifungal treatments **Mycology is the study of the Fungi** - Genetic and biochemical properties - Taxonomy - Use to humans as source for medicines (penicillin), food (beer, wine, cheese, mushrooms) - Dangers, such as poisoning or infection (Medical Mycology) More difficult to get rid of fungal infection because on the proximity with us (than for ex bacterial infection) **Fungal Morphology** - Mold (mould): is a morphological term referring to a filamentous multicellular fungus. Filamentous is described as tube-like strands called hyphae, characterized by being: - tubular, with a hard wall of chitin. They can be: - Septated - Non septated - multinucleate, with growth at tips **The surface of the colonies is velvety and powdery -** Bigger than bacterial, eukaryotes and multicellular - Yeast is a morphological term referring to a unicellular fungus - Monomorphic mold: *Aspergillus fumigatus* - Monomorphic yeast: *Criptococcus neoformans* - Dimorphic: can switch between two forms of growth, like *Histoplasma capsulatum* - Pleiomorphic: three or more possible morphologies, like *Candida albicans*  **Human fungal infections** - Superficial (outmost layers of skin and hair) - Cutaneous - Subcutaneous - Systemic - Opportunistic [Superficial mycoses\ ] - Pityriasis versicolor - Tinea Nigra - White Piedra - Black Piedra **Pityriasis versicolor** - Etiological agent: *Malassezia furfur* - More prevalent in tropical and subtropical regions - Causes small hypo or hyperpigmented macules, that can be raised and cover by a fine scale **Tinea Nigra** - Etiological agent: *Hortaea werneckii* - Occurs in tropical and subtropical regions - Contracted by traumatic inoculation of the fungus into the superficial layers of the epidermis - Appears as a solitary, irregular, pigmented macule. Usually on the palms or soles. **White Piedra** - Caused by *Trichosporon spp* - Causes white to brown swelling around the hair strand - Transmission is often mediated by shared hair brushes or combs **Black Piedra** - Caused by *Piedraia hortae* - Produces small hard nodules that surround the hair - Infected areas must often be shaved to remove the fungi [Cutaneous mycoses] - infections strictly confined to keratinized epidermis (skin, hair, nails) are called dermatophytoses- ringworm - 39 species in the genera *Trichophyton*, *Microsporum*, *Epidermophyton* - They can be geophilic (found in soil), zoophilic (transmitted by animals) or anthropophilic (transmitted from human) - infection facilitated by moist (sweating, humidity, poor drying), chafed skin (friction) **Classification** - Tinea capitis: ringworm of scalp, affects scalp and hair-bearing regions of head; hair may be lost. - Tinea corporis: ringworm of body, occurs as inflamed, red ring lesions anywhere on smooth skin - Tinea cruris: ringworm of groin, affects groin (inguine) and scrotal regions - Tinea pedis and tinea manuum: Ringworm or foot (Athlete's foot) and hand is spread by exposure to public surfaces; occurs between digits and on soles. - Tinea unguium: ringworm of nails, a persistent colonization of the nails of the hands and feet that distorts the nail bed.  [Subcutaneous mycoses] - Invade traumatized skin, rarely become systemic but can cause destructive local lesions: - lymphocutaneous sporotrichosis - mycetoma **Sporothrix schenckii** - Sporotrichosis (rose-gardener's disease) - very common saprophyte fungus that decomposes plant matter in soil - occurs when contaminated plant matter penetrates the skin and the pathogen forms a nodule, then spreads to nearby lymph nodes **Mycetoma**  - Caused by *Madurella*, *Fusarium*, *Aspergillus*, *Scedosporium*, among others - progressive, tumor-like disease of the hand or foot due to chronic fungal infection; may lead to loss of that body part. [Systemic mycoses] - Thermal dimorphism - Restricted to certain endemic regions of the world - Soil is normal habitat - Infection by inhalation of spores Pulmonary infections - *Histoplasma capsulatum* - *Coccidioides immitis* - *Blastomyces dermatitidis* - *Paracoccidioidomycosis brasiliensis* [Opportunistic mycoses] **Factors that predispose individuals to Opportunistic Mycoses** **Opportunistic Fungi** - *Candida albicans* - *Criptococcus neoformans* *:* causes cryptococosis, common infection of AIDS, cancer or diabetes patients. Infection of lungs that can disseminate to the brain. - *Aspergillus fumigatus* *:* inhalation of spores causes fungus balls in lungs and invasive disease in the eyes, heart and brain - *Pneumocystis carinii (now jiroveci)* causes pneumonia, the most prominent opportunistic infection in AIDS patients **Candida albicans** Now also candida Auris also becoming more common in Spain because of dolphin moving to Mediterranean ocean - widespread yeast - infections can range from short, superficial skin irritations to overwhelming, fatal systemic diseases - budding cells of varying size that may form both elongate pseudohyphae and true hyphae - forms off-white, pasty colony with a yeasty odor ***C. albicans* epidemiology** - Normal flora of oral cavity, genitalia, large intestine or skin of 20% of humans - Account for 80% of nosocomial (acquired In hospitals) fungal infections - Account for 30% of deaths from nosocomial infections ***C. albicans* and human disease** - Thrush -- occurs as a thick, white, adherent growth on the mucous membranes of mouth & throat - Vulvovaginal yeast infection -- painful inflammatory condition of the female genital region that causes ulceration & whitish discharge - Cutaneous candidiasis -- occurs in chronically moist areas of skin and burn patients [Fungal allergies] - Fungal spores are common sources of atopic allergies - asthma, often occurring in seasonal episodes - farmer's lung, a chronic and sometimes fatal allergy of agricultural workers exposed to moldy grasses - teapicker's lung - bagassosis, a condition caused by inhaling moldy dust from processed sugarcane debris [Antifungal treatments] **Classes of antifungals**