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Flashcards in L40_Fungi-1 Deck (19):

Bacteria are prokaryotes, what are fungi?

They are eukaryotic heterotrophs like humans


Why dont anti-bacterials have any efficacy against fungus?

Because most antibacterials are targets agains 70s ribosomes or the production of peptidoglycan


What are fungal walls made of?

Chitin and Beta-Glucan


What are the two major targets of antifungals?

beta-glucan and ergosterol (cholesterol analog of fungal membranes)


With respect to toxicity, describe why designing antibiotics is much harder for fungi

Antifungals usually have some toxicity in humans, there are fewer molecular targets and since fungi and humans have a much closer evolutionary relationship with humans the effects of antifungals have a lot of spill over into the human system.


Describe fungi ability to grow in different environments than bacteria

Fungi can grow in drier, higher-osmotic-pressure, and colder environments than bacteria: more cutaneous infections and food spoilage.


What are the two main types of fungi, how do each reproduce?

Two main types of fungi: yeast are single-celled, reproduce by budding; molds grow in hyphae/mycelia and have complex reproduction. Both make new cells by fungal mitosis; yeast and some others have closed mitosis.


What certain type of fungi have spores that can be directly diagnosed via microscopy?

Five types of asexual spores have distinctive microscopic appearances that may be used for diagnosis.


What is thermal dimorphism?

Thermal dimorphism: several important fungal pathogens grow as mold at 24C and as yeast at 37C. Yeast form has more immune-evasive properties; dual cultures can be useful for diagnosis.


What is the typical results of an immune response to fungi?

Immune response to fungal infection is granulomatous, sometimes also suppurative.


What are the consequences of most fungal pathogens being environmental?

Most fungal pathogens are environmental: little contagion or drug resistance, no eradication


What fungi is a normal flora?

Exception: C. albicans yeast is normal flora / opportunistic pathogen


What is mycotoxicosis caused by?

Mycotoxicosis is caused by eating fungal toxins (wrong mushroom or spoiled food); not fungal infection.


Can people have allergies to fungus?

Fungal allergies can also be dangerous (asthmatic reaction)`


How can fungal infections be diagnosed?

Fungal infection diagnosed by PPD, KOH-mount microscopy with fungal stains, culture on Sabouraud’s agar; PCR available for dangerous systemics; serology for epidemiology.


What are the major classes of antifungals?

Polyenes, Azoles, Echinocandins


What do polyenes target, what are their side effects? what is the major one?

Polyenes are highly effective and broad-spectrum but toxic – Amphotericin B is the only systemic and is nephrotoxic (can be used during pregnancy


What do Azoles target, what is one of the main ones, what species does it kill?

Azoles are less toxic and inhibit ergosterol synthesis; different ones optimally active against different fungi; Fluconazole/Diflucan major one, treats candidiasis and cryptococcosis


What do Echinocandins target, what are they highly effective against?

Echinocandins are low-toxicity and inhibit beta-glucan syn, highly effective against candida and aspergillus (both are opportunistic pathogens)