2. Fungal Overview
• More than 50,000 species exist
• Only 100 to 150 species recognized agents of human disease
• About 25 cause the majority of human disease
• Fungi are found everywhere
• Soil
• Water
• Plants (leaves, roots, fruits)
• Animals
• Human skin
3. Fungal Infections
• Any fungal infection is termed mycosis
• Generally cause chronic infections – fungi grows slowly
• Often opportunistic pathogen
• Mycoses divided into five groups
• Systemic
• Subcutaneous
• Dermatomycoses or cutaneous mycoses
• Superficial mycoses
• Opportunistic mycoses
4.
5. • Superficial mycoses
• Localized along hair shafts and in superficial epidermal cells.
• Rarely invades the deeper tissues
• E.g. dermatophytes
• Subcutaneous mycoses
• Infection beneath the skin (subcutaneous tissue0
• Caused by saprophytic fungi from soil and vegetation – Introduced through trauma
• Infection occurs by direct implantation of spores or mycelium into punctured woun
• Rarely spreads systemically
• Usually form deep, ulcerated skin lesions of fungal masses
• Most commonly involving the lower extremities (feet or legs)
6. • Systemic mycoses
• Usually caused by fungi found in soil
• Inhalation is route of transmission
• Infection starts in the lungs and spreads to other body
tissue
• Often fatal if infection widespread
• Eg histoplasmosis and coccidiodomycosis
7. Dermatomycoses or cutaneous mycoses
• Infection of epidermis, hair and nails
• The fungi are called dermatophytes
• These dermatophytes secrete keratinase that breaks down keratin
(protein found in skin, hair and nails)
• Infection transmitted from human to human or animal to human
• by direct contact with infected hairs and epidermal cells (at
barber shop clippers or shower room floor)
8. SUPERFICIAL MYCOSES
• disease of the skin and its appendages caused by fungi
• They have the affinity to keratin rich tissues and produce dermal
inflammatory response, intense itching,
• Superficial mycoses are common worldwide
• affect 20% to 25% of the world's population, and the incidence of superficial
mycoses continues to increase
• Etiological agent consists of dermatophytes, yeasts, and
nondermatophyte molds
9. Dermatophytosis (tinea)
• a group of closely related fungi infecting skin, hair, and nails in
living host including man.
• They produce an infection called dermatophytosis, also known as
ringworm or tinea
• The skin infections caused by nondermatophytic fungi are known
as dermatomycoses
• Hair dermatomycoses – Piedra
• Nail dermatomycoses - onychomycosis
10. Depending on site of infection;
• Tinea unguium – nails (onychomycosis)
• Tinea pedis - foot
• Tinea capatis - scalp
• Tinea corporis - body
12. Other Superficial mycoses
pityriasis versicolor (Malassezia furfur)
tinea nigra (Hortea werneckii)
black piedra (Piedraia hortae)
white piedra (genous Trichosporon) Pityriasis versicolor
chronic infection
occur as patches of discolored skin
inflamation, scaling, irritation are minimal
lesions fluoresce under Wood’s lamp
PIEDRA - endemic in tropical countries
Black piedra -Piedra hortae: nodular infection of the hair
shaft
White piedra - Trichosporon spp.: large, soft, yellowish
nodules on the hair
TINEA NIGRA – Hortaea werneckii
appear as a dark discoloration often on the palm
14. Cryptococcus Neoformans
• Is a yeast fungus that cause systemic infection particularly in
immunocompromised patients like HIV/AIDS individuals
• Mostly found in the environment around the world
• Commonly isolated in Soil and bird droppings especially of pigeons
• Transmitted through inhalation into the lungs
• Infects the lungs or the central nervous system (CNS) ie the brain
and spinal cord
• In the lungs it causes Pneumonia
• In the CNS it causes Cryptococcal Meningitis
15. Candida Albicans
• Is a yeast fungus that cause systemic infection
• Is a normal flora on the skin and inside the body
• Normally dwells in the mouth, throat, gut, and vagina, without causing
problems.
• Can only cause infections if it grows out of control or if it enters deep into the
body.
• Can be transmitted through physical contact
• Most common mother to child during birth
• Causes Candidiasis
• Oral Candidiasis (thrush)
• Virginal Candidiasis
• Invasive candidiasis
16. SYSTEMIC
Histoplasmosis
Caused by Histoplasma capsulatum (dimorphic fungi)
• found in the soil
• Infection of the lungs
• Inhaled spores germinate to the yeast form
• Taken up by macrophages to mediastinal lymph nodes, spleen and liver
• granulomata form and heal causing Calcification
• Symptoms-pneumonia
• Infection through chicken or bat droppings
17. Management
• Amphotericin B
• Oral itraconazole
• Control is by avoiding exposure or using itraconazole as long term
suppression in chronic disease
18. Paracoccodioidomycosis
• South American Blastomycosis
• Paracoccidio species- Paracoccidioides brasiliensis
• Infects mucous membranes mainly nose and throat.
• Painful ulcerative granulomas-destruction of tissue leading to loss of
function.
