Fungal infections 2 Flashcards
Other medically important fungi include
Aspergillus found/important
found throughout the world
Ecologically important saprophytic cycle (biomass recycling)
Expert in making and secreting compounds! (many are toins; used to breakdown biomass)
Adapted to high temperature - very hot in compost
Why Aspergillus Problematic treatment
acquired resistance to antifungals
and formation of biofilms
Aspergillus entry route into body
inhale spores into lungs and paranasal sinuses
Is a mold → hyphal grow will traverse cellular barriers!
is an angioinvasive pathogen → looks for blood vessles to grow inside → will destroy blood vessels
Aspergillus CNS infection
Relatively infrequent opportunistic
Brain parenchymal aspergillosis may cause stroke-like syndromes, mycotic aneurysms, or hemorrhage [massive strokes - growing inside vessels]
most common pathogenic species of Aspergillus
A. fumigatus
Aspergillus morbidity
very high
asthma, cystic fibrosis, toxicoses → produces several mycotoxins; most common aflatoxin
also high burden in food industry - exposure to toxins
Will form biofilms → harder to treat
Problem when requiring catheterization (chemo, dialysis) → catheter becomes source
Aspergillus diagnosis
direct microscopy (preferably using optical brighteners) and microbiological culture
Aspergillus treatment
For CNS infection: Voriconazole
Azole-resistant → AmpB (not as effective, and many side effects)
Biofilms
makes everything more resistant to anything
is an assemblage of surface-associated microbial cells that is enclosed in an extracellular polymeric substance [EPS] matrix.
Blastomyces spp cause
blastomycosis, generally a lung and skin
infection, but can disseminate
Mostly B. dermatitidis
Blastomyces Niche
Environmental fungi, but has restricted niches
moist soil and in decomposing organic matter such as wood and leaves in humid areas
Most cases occur in the endemic areas - area expanding
Blastomyces are ___ dynamic
Thermally dimorphic fungi
Mold in environment → yeast inside hosts
Blastomyces cycle
Blastomyces risk groups
Is a primary pathogen but at risk:
Live in an endemic area
Participate in outdoor activities that expose them to wooded areas
Have weakened immune systems
It is a veterinary problem, particularly for dogs - but not continuous, cannot spread from pets, need to inhale spores from environment
Blastomyces CNS
Untreated symptoms can develop into disseminated blastomycosis (20% in pediatric and 40% in AIDS)
[~50% of infected people will show symptoms]
Blastomyces diagnosis
growth from patient sample - lung culture
Broad neck is strong indicator
Serology not accurate
CNS infection must have CSF positive sample
Blastomyces treatment
AmB for severe infection,
followed by prolonged azole regimen
can progress to acute respiratory distress
syndrome (ARDS) - when it comes back more leathal - not very well understood
most common invasive fungal pathogen
Candida
Candida is
A dimorphic fungus, some species part of microflora - NOT ALL are dimporphic
Yeast form → commensal
Hyphal form → pathogen
most common cause of Candida disease
C. albicans
Makes diagnostic difficult - is part of normal flora!
Mostly an “endogenous” infection
C. albicans common cause of ___ infections
Common HAI [hospital aquired infections]: bloodstream; cathether-associated; various organs (kidney, eye, brain)
CNS = very rare - usually terminal stage of AIDS
Invasive candidiasis
internal orgon
blood, heart, brain, eyes, bones, kidney, etc.
Source of candidiasis
breach on normal cellular barriers (surgery, catheter, etc.)
Commonly categorized as a contaminant – challenging diagnosis!
Candida spp risk
long-term antibiotic usage, GI-UT (urinary tract) surgery, medical immunosuppression
Candida diagnosis
is based on the identification of Candida spp. in the CSF culture
Brain imaging helpful to determine the clinical manifestation
Candida treatment
If CNS
liposomal AmB with or without flucytosine initially, followed by maintenance therapy with fluconazole
Antifungal resistance a concern - C. auris currently a superbug
Other antifungals (Echinocandins/NEW) won’t go inside CNS
If suspected endogenous infection, removal of prosthetic material needed
The rise of Candida auris
Very likely due to climate change
Why mycoses are so hard to treat
- Delayed diagnosis
- Few antifungals
- Toxic side effects
New oputuntites - medical intervention ex. cathatory
New platforms and niches! Appearance of superbugs! - special adhesions - bind to surfeces
New land! Ease of travel, climate change, etc.
WHO first ever list of fungal pathogens
