Fungi Flashcards by Erin Nolan

2 Forms of Fungi

QUIZ/EXAM Q***

1) Yeast
-unicellular organism
-asexual reproduction, budding

2) Mold
-multicellular organism
-sexual reproduction

How well did you know this?

Not at all

Perfectly

What reproduces more slowly?
a) yeast
b) mold

a) yeast

How well did you know this?

Not at all

Perfectly

What is more difficult to treat?
a) yeast
b) mold

a) yeast

due to intrinsic resistance (property that doesn’t need to be learned or acquired)

How well did you know this?

Not at all

Perfectly

Fungal characteristics (3)

1) contain membrane bound organelles

2) distinct organelles:
-Mitochondria (cell generator)
-Endoplasmic reticulum (manages cellular export)
-membrane bound nucleus

3) sexual and asexual reproduction

How well did you know this?

Not at all

Perfectly

What is one of the biggest risk factors for fungal disease?

antibiotic use

How well did you know this?

Not at all

Perfectly

Fungal Cell Wall

Ergosterol: similar to Cholesterol and is a primary sterol that makes up the cell wall

NO peptidoglycan

major structure: Chitin

exploited for diagnosis typically

new drugs use the cell wall as a target

How well did you know this?

Not at all

Perfectly

Functions of the Fungal Cell Wall (3)

Ergosterol:

1) gives shape to the fungi

2) gives strength by protecting them from organic solvents and UV light

3) secretes enzymes from their walls - able to hydrolyze sugars for nutrition

How well did you know this?

Not at all

Perfectly

Primary fungal reproductive structures

spores or conidia

can transmit spores, very bad for patients

How well did you know this?

Not at all

Perfectly

Fungal reproduction is
a) fast
b) slow

b) slow

mold takes up to 6 weeks to grow in lab

yeast (unicellular) is a little quicker, 48 to 72 hours

How well did you know this?

Not at all

Perfectly

Many medically relevant fungi are ____________

environmental

How well did you know this?

Not at all

Perfectly

Medically relevant yeasts (2)

1) Candida app

2) Cryptococcus spp

How well did you know this?

Not at all

Perfectly

Candida app

normal flora of the GI tract and often colonized the skin and the environment

leads to infections in immunocompromised to some degree

can lead to several aetiologies
-candidemia
-oral thrush - advanced immunocompromised (radiation, chemo, AIDS)
-vaginitis (most common)
-diaper rash

How well did you know this?

Not at all

Perfectly

Risk factors for invasive Candida app infections (many)

critical illness

organ transplant

neonates

antibiotics*

total parenteral nutrition

hemodialysis

chemo

How well did you know this?

Not at all

Perfectly

Cryptococcus spp

can lead to disease/ infection in those with altered immune status or underlying morbidity

environmental - found in soil and in dried animal faeces, specifically associated with bird poop or guano

can lead to pneumonia, fungemia (disseminated), cryptococcemia (meningitis) and cutaneous infection

contains large capsule around the yeast cell - helps it evade immune mediated phagocytosis

How well did you know this?

Not at all

Perfectly

Most medically relevant Cryptococcus spp (2)

1) Cryptococcus neoformans

2) Cryptococcus gattii

How well did you know this?

Not at all

Perfectly

Medically relevant molds (4)

1) Dermatophytes

2) Zygomycetes

3) Hyaline Molds

4) Dimorphic Fungi

Dermatophytes

distinct group of fungi that ONLY nail, skin, hair → use keratin as carbon source

produce keratinase which helps break down nail, skin, hair

3 different genus of Dermatophytes

1) Trichophyton - “Tri” - infects hair, skin and nails

2) Microsporum - infects skin and hair

3) Epidermophyton - infects skin and nails

Examples of Dermatophytes (many)

ringworm

Athlete’s foot

Tinea corporis (body)

Tinea pedis (foot)

Tinea capitis (head)

What is one of the few fungi that can infect an immunocompetent person?

dimorphic

Dimorphic fungi (6)

1) Histoplasma capsulatum

2) Blastomyces dermatiditis

3) Coccidioides immitis

4) Paracoccidiodes brasilensis

5) Sporothrix schleferi

6) Taloromyces marneffei

Histoplasma capsulatum

found around the world

clinical presentation include fever, sweats, weight loss, fatigue, and respiratory symptoms

CNS involvement in 5% to 20% of cases of acute disseminated histoplasmosis, presenting as chronic meningitis

disseminated disease are rare but seen

Blastomyces dermatiditis

Massachusetts, NY, Kingston, Northern Ontario, Montreal, St. Lawrence Valley

presents as nonspecific febrile acute or chronic pulmonary disease mimicking CAP and/or malignancy

ultimately to disseminated disease involving cutaneous, genitourinary, and bony lesions

Coccidioides immitis

pulmonary involvement and in most cases is asymptomatic

symptomatic infection presents with fever, cough, and chest pain and may mimic CAP

disseminated disease can occur locally with pleural or pericardial invasion or any organ of the body

disseminated disease can involves cutaneous, genitourinary, and bony lesions

Paracoccidiodes brasilensis

found in Brazil, South America

Sporothrix schleferi

likes plants, “rose grower’s” fungus on rose thorns infection at the site

Taloromyces marneffei

exclusively in Southeast Asia - Vietnam, Laos, Vietnam War - reactivates when you get immunocompromised

Temperature dependent dimorphism

2 different morphologies: yeast and mold infects you as a yeast, found in the environment as a mold yeast at 37C mold at 25C if it cannot live at that temperature, won’t infect you

Infection Classification (4)

1) Superficial or cutaneous mycoses -e.g. dermatophytes - like skin, hair, and nails -nail infections, dandruff, ringworm - break down keratin 2) Subcutaneous mycoses -more embedded 3) Systemic mycoses -in blood -fungemia 4) Opportunistic -immunocompromised

T or F: Most pathogens are opportunistic

TRUE

Opportunistic fungi definition/characteristics

immune system needs to be compromised cause significant illness in the immunocompromised, those with prosthetic/IV devices and hematologic malignancies molds - can result in sinus infections, respiratory diseases and fungemia

Opportunisitic fungi (5)

1) Aspergillus 2) Penicillium 3) Paeciliomyces 4) Acremonium 5) Fusarium

Most common invasive mold

Aspergillus

has become the major cause of morbidity and mortality in immunocompromised patients lung cancer, cystic fibrosis almost 2/3s (61%) of patients with invasive aspergillosis have an underlying hematologic disease, or have undergone bone marrow transplantation

Zygomecetes (Mucorales) Molds

fast growing fungi characterized by primitive coenocytic (mostly aseptate) hyphae known as “lid-lifters” (2 days) environmental - soil, dung and vegetative matter extremely aggressive disease as the organism does not respect tissue planes including devastating rhino-orbital infections and wound infections

T or F: anti-fungals have more side effects compared to other medications like antibiotics

TRUE

Anti-fungal therapy effects (5)

effects: 1) Lanosterol synthesis 2) Ergosterol synthesis 3) Nucleic acid synthesis 4) Forms membrane pores 5) Cell wall synthesis

Lab detection of fungi

gram stain + additional stains from specimens - may see fungal elements culture on specialize media: -Yeast: 1-3 days -Dermatophytes: 1-3 weeks -Systemic fungi: 3-6 weeks variety of stains used can help identify fungi