Transcript Fungal Diseases

Fungal Diseases - Mycoses
Superficial Fungi
• Pityriasis versicolora is a superficial mycosis which
appears on the upper torso, arms, and abdomen as
hyper/hypo pigmented macular lesions which scale
leaving the area looking dry and chalky
– Malassezia furfur is a lipophilic yeast which is part
of the normal microflora of the skin; grows mostly
a a yeast, but sometime produces a hyphal form.
• grow in the skin is activated by certain
predilecting factors like exposure to sunlight,
etc.
• organism is identified in KOH preparation of the
white, chalky scales; organism appears a yeast
cells among hypae
Cutaneous Fungi-Dermatophytes
• Dermatophyte Fungi are mold fungi which grow in tissues
containing keratin; Thus, they are limited to skin, hair and nails.
– cellular immune response to the presence of fungi in the skin
evokes an inflammatory response often described as “ ringworm” or
“tinea”
– infections are often classified by the area affected; such as tinea
capitis, tinea pedis, tinea manus, tinea ungium, etc.
– there are three main dermatophyte genera which infect humans
• Trichophyton
• Epidermophyton
• Microsporium
– species within these genera are grouped based upon their source
• anthropophilic
humans
• zoophilic
animals
• geophilic
soil
– dermatophytes are diagnosed by finding septate hypha and
asexual(anamorphic) spores in the scraping of infected tissue.
Subcutaneous Fungi-
Mycosis
• Lymphocutaneous Sporotrichosis
nodular and ulcerative
lesions which develop along the lymph channels
which drain the primary site of inoculation; when the lymph
gland is infected, the fungus disseminates to other areas
– Sporothrix schenckii a dimorphic fungus
• fungus grow in soil and on plants and spores are
inoculated into subcutaneous tissues by thorns and
sharp needle of certain plants, like roses.
• Diagnosis is based upon finding yeast cells in lymphatic
fluid from lesions
• In the laboratory at 25 C, characteristic colonies
containing delicate branching hyphae with unique rosette
conidia
Systemic Fungi -
Systemic Mycoses
• Histoplamosis - acute necrotizing, caseous granuloma of the lungs;
in immunocompromised people or those exposed to high
infectious dose, the yeast cells invade the mediastinal and hilar
lymph nodes and disseminate via macrophages to the liver and
spleen; in immunocompetent people the cellular immune
response limits the spread of the yeast and confines the
infection to mild flu-like symptoms; most primary infections are
asymptomatic; has many features similar to tuberculosis
– Histophasma capsulatum
dimorphic fungus found in nature;
mutiplies extensively in area where bird feces accumulate
• Epidemiology - endemic geographical area; macroconidia(spores) are inhalated
and taken into the lungs
• Blastomycosis - chronic granulomatous ans suppurative disease of
the lungs resulting in small areas of pulmonary
consolidation; when confined to the lungs resolution results in
scarring; dissemiation involves the skin, bones,
– Blastomyces dermatiditis
dimorphic fungus found in nature
– Epidemiology
broad geographic area with source unknown
Systemic Fungi
- Systemic Mycoses
• Coccidioidomycosis
chronic, necrotizing mycotic
infection of
the lungs which pathologically resembles
tuberculosis; begins
as a bronchopneumonia with its
inflammatory infiltrate;
disseminates in
immunocompromised people to many sites
including skin, bones, meninges,liver, spleen.; symptoms
range from asymptomatic to mild respiratory symptoms to
diverse set of symptoms associated with the affected areas;
another “great imitator”
– Coccidioides immitis
dimorhic fungus which
grows in the soil of the S.W. United States; spores called
arthrospores are inhaled into the alveoli and terminal
bronchioles where they enlarge into “spherules”; spherules
fill with endospores(yeast-like cells) which are released to
form more spherules;
• Epidemiology
• Diagnosis
Systemic Fungi
• Cryptococcosis
Systemic Mycoses
primary disease of the lungs with
gramulomas and consolidation; readily spreads to the
meninges and brain causing “meningoencephalitis”
– Cryptococcus neoformans - only systemic fungus which is not
dimorphic; its is a highly encapsulated yeast which accounts for its
virulence
• Epidemiology
• Diagnosis
Opportunistic Fungi
Mycoses
• Candidia albicans
– a common unicelluar fungus which is part of the flora
of the oral cavity, vagina, and gastrointestinal tract; in
this setting in becomes an opportunist especially in
immunocompromised people
– in culture, it grow as blastospores, pseudohyphae,
and septate hyphae
– candidiasis
the collective term for infection
involving Candida
• cutaneous
• vaginal
• systemic
• Aspergillus fumigatus/ A. flavus
• Pneumocystis carnii