Fungal Pathogens I

Question 1

Pathogenic fungi are relatively

Answer 1

Rare

Out of 1.5m species, 8000 plant pathogens and 600 human pathogens

Question 2

Types of fungi

Answer 2

1. Filamentous fungi

2. Yeasts

Question 3

Filamentous fungi

Answer 3

e.g. Aspergillus
Long hyphae
Airborne spores

Question 4

Yeasts

Answer 4

e.g. Saccharomyces cerevisiae
Unicellular
Budding

Question 5

Dimorphic yeast

Answer 5

Switch between filamentous and yeast growth forms
e.g. Candida albicans
Response to change in environment

Question 6

Human disease types

Answer 6

1. Superficial
2. Subcutaneous
3. Systemic

Question 7

Mycosis

Answer 7

Fungal disease

Question 8

Superficial mycoses

Answer 8

Skin, hair, nails, mucous membranes

Question 9

Subcutaneous mycoses

Answer 9

Through puncture wound

Question 10

Systemic mycoses

Answer 10

Deep organ or disseminated

Question 11

Superficial mycoses species

Answer 11

Dermatophytes (athletes foot)
Candida (thrush)
Malasezzia (dandruff, pityriasis versicolor)

Question 12

Subcutaneous mycoses species

Answer 12

Chromoblastomycosis
Madurella mycetomatis (madura foot)
Rare infections

Question 13

Primary pathogens

Answer 13

Exposure causes disease in healthy individuals

Question 14

Opportunistic pathogens

Answer 14

Only cause disease in immunocompromised

Question 15

Dermatophytes

Answer 15

Medical term ‘tinea’ skin
Named according to site of infection
Tinea corporis - ringworm
Tinea captis - cradle cap

Question 16

Dermatophyte genera

Answer 16

1. Microsporum
2. Epidermophyton
3. Trichophyton

Filamentous - soil, animals, people

Produce keritinase (virulence factor)

Question 17

Dermatophytes produce

Answer 17

Keritinase
Can digest keratin so substrate = skin, hair, nails
Virulence factor

Question 18

Dermatophytes are divided into 3 groups based on habitat:

Answer 18

1. Anthropophilic
2. Zoophilic
3. Geophilic

Question 19

Anthropophilic dermatophytes

Answer 19

Reservoir is man
Host is man

Trichophyton rubrum (chronic athletes foot)

Question 20

Zoophilic dermatophytes

Answer 20

Reservoir is animal
Can infect man

Microsporum canis

Question 21

Geophilic dermatophytes

Answer 21

In soil

Question 22

Zoophilic species give the most

Answer 22

Severe inflammatory reaction

Question 23

Candida albicans is present in

Answer 23

50% of population in mouth and GI tract
20% women in genital tract
Commensal

Question 24

Candida parapsilosis causes disease in

Answer 24

Neonates

Question 25

Most disease causing candida are in the

Answer 25

CTG clade

Atypical genetic code

Question 26

Candida infection sites

Answer 26

1. Mouth, genitals, skin, nails

Predisposing factors - antibiotics, pregnancy, diabetes

Question 27

Subcutaneous mycoses are

Answer 27

Geographically limited
Wide range of organisms
Effect subcutaneous layers, though they can’t get in by themselves

Question 28

Subcutaneous mycoses develop

Answer 28

Slowly

Difficult to treat

Question 29

Invasive mycoses cause

Answer 29

Systemic life threatening infection

Primary and opportunistic

Question 30

As many die from top 10 fungal diseases as

Answer 30

TB and malaria

Question 31

90% of all fungal related deaths are from

Answer 31

Cryptococcus, candida, aspergillus, pneumocystis

Question 32

Opportunistic mycoses cause the majority of

Answer 32

Deaths from infection

Question 33

4 main primary pathogens

Answer 33

1. Histoplasma capsulatum
2. Blastomyces dermatiditis
3. Parracoccidioides brasiliensis
4. Coccidioides immitis

Inhalation of spores

Geographically limited

Question 34

Primary fungal pathogens are all

Answer 34

Thermally dimorphic
Saprophytic filamentous at 25 degrees
Parasitic yeast form at 37 degrees

Question 35

Primary fungal pathogens cause

Answer 35

Mild respiratory infection

But can progress to severe pulmonary or disseminated infection in immunocompromised (10-25% HIV patients)

Question 36

Disseminated infections predisposing factors

Answer 36

Severely immunocompromised - neutropenia, cancer, bone and organ transplant
major burns, long term catheters, abdominal surgery

Question 37

Systemic candida infection

Answer 37

Varies with underlying disease (33% bone marrow transplants)

30-50% mortality rate with treatment

Question 38

Candida auris

Answer 38

Ear pathogen discovered in Japan in 2009

Reached UK in 2013

Question 39

Candida auris causes both

Answer 39

Superficial and systemic disease

Multidrug resistant

Question 40

Aspergillosis

Answer 40

Mainly caused by A. fumigatus, A. flavus

Inhalation of spores (sick building syndrome)

Question 41

Aspergillus disease types

Answer 41

1. Allergy (Asthma)
2. Toxins
3. Invasive bronchopulmonary aspergillosis (opportunistic)
4. Disseminated aspergillosis 60-90% mortality

Question 42

Cryptococcosis species that cause disease

Answer 42

Cryptococcus neoformans
C. gattii

Inhaled

Dimorphic
Capsulate yeast (capsule is a virulence factor)
Soil and avian habitats

Question 43

Cryptos mainly cause

Answer 43

Pulmonary disease, chronic
Meningitis (disseminated)
AIDS patients
Can be an intracellular pathogen

Question 44

Pnuemocystis

Answer 44

Pulmonary and disseminated infection
AIDS
5-40% mortality
VBNC (lacks genes for a.a.biosynthesis)
Obligate parasite, originally classed as a protozoan

Question 45

Emerging fungal diseases in animals

Answer 45

Psuedogymnoascus destructans
White nose syndrome in bats

Batrachochytrium dendrobatiditis
Amphibian skin disease