what makes a fungus
- eukaryotes (have membrane enclosed nucleus)
- heterotrophs (require pre formed source of C for growth (secrete degradative enzymes)
- saprophytic (obtain nourishment from dead matter)
- parasitic (obtain nourishment from live organic matter)
- often take form as respiratory or skin infections
- mycosis should always be considered in immunocompromised patients
- specialized antifungal agents are needed to treat
fungal cell walls
made of chitin (bacteria peptidoglycan)
- means not affected by ABX!!
- contain ergosterol (human cell walls don’t contain this so antifungals don’t kill human cells)
How fungal cells grow
- filamentous
- yeast like
- dimorphic
filamentous fungi
- “mold like”
- the vegetative body is a mass of threads with many branches. the mass is a mycelium which grows by branching and tip elongation.
yeast like fungi
- single unconnected spheroid cells, reproduce by budding
- spaghetti and meatballs
dimorphic fungi
-yeast like in one environment and mold like in another. they can be air or water borne where they germinate and establish new colonies. They reproduce either sexually or asexually.
fungal reproduction
- sporulation (with and without sex, most human pathogenic fungi reproduce asexually)
- spores are metabolically dormant (released in huge numbers via wind and water then germinate to establish new colonies)
Lab diagnosis
-under scope with KOH prep (KOH digests keratin)
classification of pathogenic mycoses
- where on body they infect (cutaneous, subcutaneous, systemic)
- what type of body they infect (healthy vs immunocompromised)
cutaneous pathogenic mycoses
- dermatophytes!!
- reside on humans, animals, soil
- infect superficial keratinized structures (hair, skin, nails)
- human to human or animal transmission
- diaper rash! (fester in warm, moist environments)
subcutaneous pathogenic mycoses
- infect dermis, subcutaneous, tissue and bone
- reside in soil or decaying vegetation
- acquired through traumatic lacs or puncture wounds (usually in tropical enviorns)
systemic pathogenic mycoses
- some can infect healthy people
- some primarily infect sick people
- usually confined to geographic areas
if get fungal infection, what do you wonder?
- is pt immunocomp? do they have aids? diabetes?
- if someone on abx and still sick, wonder fungus?
opportunistic
- type of systemic pathogen
- infect immunocompromised host (BM transplant, AIDS, chemo, etc)
- may be normal flora going out of control
candida
- oral or cutaneous candidal dermatitis
- yeast growth in different areas
trichophyton species
- tinea corpis: body (ring worm)
- tinea cruris: groin (jock itch)
- tinea pedis: foot (athletes foot)
- tinea unguinum: nail
- tinea capitus: scalp
sporothrix schenckii
- “rose thorn”
- spopotrichosis
histoplasma capsulatum
- histoplasmosis (also blastomyces)
- ohio river valley (mississippi river)
pneumocystis jiroveci
- PCP pneumonia
- classic presentation: chest radiograph report reads “bilateral, diffuse, perihelia, fine, reticular, interstitial nodular opacification, appears somewhat granular”
- pt fatigued, coughing, short of breath
rocky mountain spotted fever
- southeast (NC)
- fever and rash
lyme disease
east coast
coccidomycosis
arizona and SA (arid climates)
rhizopus
- common in bread and compost mold
- can kill in week if inhaled
