fungi characteristics
eukaryotic
can be unicellular or multicellular filamentous
some species are dimorphic
usually in 2 forms (complex life cycle)
mainly cause self-limiting diseases
usually only affect immunocompromised individuals
fungi environment
nature and human microflora
fungal infections types
endemic mycoses
opportunistic mycoses
subcutaneous mycoses
superficial and cutaneous mycoses
systemic mycoses
endemic mycoses
only in some countries
CAN cause disease in healthy individuals
opportunistic mycoses
in immunocompromised patients
subcutaneous, superficial, and cutaneous mycoses
skin and layers of the skin
systemic mycoses
usually from a cut or inhalation
fungi information
at least 100,000 species
way <1% cause disease
usually degrade organic waste in environment
cytoplasmic membrane contains sterols
cell walls are chitin, mannon, and glycan
do not photosynthesize
almost all are strict anaerobes
what kind of sterols do fungi use?
ergosterol (as compared to cholesterol in humans)
are fungi cell walls the same as plant cell walls?
no
pathogenic fungi
dimorphic
unicellular form is yeast
multicellular filamentous form is mold, hyphae, and mycelium
asexual reproduction of fungi
budding
hyphae
can either have septums or not
mycellium are many hyphae together
fungal reproduction structures
asexual: conidia in mold
sexual: sporangia (exospores)
fungal morphology
asexual: sporangiophore is stalk, then sporangium is covered by sporangiospore
sexual: conidophore is stalk, with conidia at the end
entry of fungi
innate immune system to pathogenic fungi in healthy individuals is high
skin and mucosal surfaces are primary barriers
bacterial flora compete with fungi
alterations of flora increase entry
trauma allows entry into sterile parts of the body
Body's response to fungi
nonspecific inflammatory response
neutrophil and macrophages phagocytose as primary mechanism
cell-mediated immunity
antibodies
what is the most important host defense against fungi?
cell-mediated immunity
what is the minor host defense role?
antibodies
fungi damage determined by...
virulence of organism
size of inoculum
adequacy of host defense
fungi diagnosis
direct microscopy
histopathology
culture
serology
antigen detection
what diagnosis is usually used?
culture, and it takes ~6 weeks
what is used if the fungi is chronic?
antigen detection (antibody assay)
fungi treatment
small amount of options
can be life long if inefficient
usually taken for months to years
top 3 endemic mycoses in US
histoplasmosis
blastomycosis
coccidioidomycosis
histoplasmosis
caused by histoplasma capsulatum
does histoplasma capsulatum have a capsule?
no
H. capsulatum
grows in soil with bird and bat excreta
transforms into yeast after inhalation to alveoli
immunity depends on T-cells and activated macrophages
causes acute and chronic pulmonary and disseminated disease (most have no symptoms though)
is dimorphic
life-lo
H. capsulatum occurance
mississippi and ohio valleys
H. capsulatum treatment
amphotericin B for severe
itraconazole for mild to moderate
if severe: B 1st, then itra
H. capsulatum diagnosis
ELISA assay
H. capsulatum prevention
don't breath it in
H. capsulatum infection route
mold>inhaled>yeast>phagocytosed>establish infection
blastomycosis
caused by Blastomyces dermatiditis
B. dermatiditis environement
Mississippi river valley and SE and N central states
soil mold that transforms into yeast after inhalation into alveoli (dimorphic)
B. dermatiditis
triggers immunity that depends on polymorphonuclear leukocytes, T-cells, and macrophages
B. dermatiditis symptoms
skin lesions
pneumonia
other pulmonary and disseminated infections
B. dermatiditis diagnosis
grow and observe (can take weeks)
B. dermatiditis treatment
amphotericin B for severe
itraconazole for mild to moderate
take for .5-1 yr
coccidioidomycosis
caused by 2 species: coccidioides immitis and coccidioides posadasii
coccidioides species environment
SW us
grow in desert soil
coccidioides species
have large endospore spherule in body
triggers imunity that depends on PMNS, lymphocytes, and macrophages
dimorphic
coccidioides species symptoms
wide spectrum of pulmonary diseases
skin diseases
osteoarticular lesions
ascesses
meningitis
coccidioides species treamtent
amphotericin B for severe
itraconazole or fluconazole for mild to moderate
flucanozole for life if meningitis
Are coccidioides species infectious?
yes, very
~80% of people in area have been infected
endospore can prolong infection, but most are asymptomatic
do the coccidioides species have a yeast form?
no, the spherule replaces the yeast form
other mycoses in America
paracoccidioidomycosis
penicilliosis