Fungi

Question 1

Why is it hard to treat fungi?

Answer 1

Fungi are closer to animals than to plants esp. humans. Hence there are many similarities between the two, that is why it is so difficult to treat. It is hard to find a treatment which will only fungi and not damage us.

Question 2

Poisonous mushrooms

Answer 2

Amatoxins - damage the intestine, kidneys and liver by inhibiting RNA polymerase

Current treatment: remove toxin from system.
Increase excretion of toxin.
Supportive care - as it may be too late for treatment

Question 3

Food spoilage fungi and mycotoxins

Answer 3

Mycotoxins:
- Acute (moderate levels of toxins + specific, observable disease)
- Chronic (Low levels of toxins + weight loss, infertility, failure to thrive)
E.g. Aflatoxins (Aspergillus flavus toxin - Turkey X disease). Most potent natural carcinogen - liver cancer

Question 4

Allergenic fungi and hypersensitivity

Answer 4

Compromise the immune system which then causes other problems.
Fungi can grow in damp conditions and then make allergenic spores and volatiles

Question 5

Commonesal and pathogenic fungi

Answer 5

• Superfical
• Cutaneous
• Subcutaneous mycoses

Infect skin and underlying tissue

Invasive fungal infections (x3)

Question 6

Superficial mycoses

Answer 6

Infection of hair shaft - piedras

Can be prevented by good personal hygiene and Treat with cleansing agents of the body

Question 7

Cutaneous mycoses: Dermatomycoses

Answer 7

Ringworm of the body (Tinea corporis)

Clinical Aspect:

• blister like lesions dry to leave scaly ring
• treat by changing env

Question 8

Dermatophytes

Answer 8

Fungi that cause dermatomycoses
Examples:
- Trichophyton
-Microsporum

Have a distinctive spore structure

Easily passed from one person to another

Question 9

Subcutaneous mycoses

Answer 9

Caused by soil fungi - not spread by person to person, instead puncture

Disease develops very slowly, production of subcutaneous nodules, where can drain to the skin surface / lymphatic system.

Difficult to treat

Lots of pigments in cell wall - difficult to treat

Question 10

Example of Subcutaneous mycoses

Answer 10

Chromoblastomycosis

Caused by black mould that exist worldwide

Question 11

Aspergillus

Answer 11

Aspergillus fumigatus

• makes tough, pigmented spores which are hydrophobic and resistant to high temperatures
• Opportunistic infection - gets more serious based on the immunocompetency of the host - hard to treat and high mortality.
• Aspergilloma (fungal ball) will be inhaled into the lung and will be inhaled
• Invasive pulmonary aspergillosis
• Disseminated aspergillosis

Question 12

Candidiasis: Candida albicans

Answer 12

Single celled yeast that forms pseudophyphae

Endogenous + can be passed from person to person

Question 13

Candidiasis can take many forms:

Answer 13

• Vagina (vulvocandidasis)
• oral candidiasis/ thrush
• Disseminated candidiasis after surgery or immunosuppressed

Question 14

Two forms of Cryptococcosis

Answer 14

C. neoformans (env. esp. decaying of wood)

C. gattii

Question 15

Virulence factor of cryptococcosis

Answer 15

a large capsule which protects the organisms from immune system

Question 16

Disease cryptococcosis

Answer 16

Cryptococcal meningitis

Cryptococcal pneumonia

Question 17

Process of cryptococcal infection

Answer 17

• Acquired from the env.
• The first site of infection is in the lungs
• then can disseminate

Question 18

Cryptococcus neoformans

Answer 18

2 species

• opportunistic
• Major AIDS pathogen
• Worldwide
• pigeons (in poo, then dries and then we inhale)

Question 19

Cryptococcus gattii

Answer 19

Most primary pathogens

- restricted areas

Question 20

Diagnosis of fungal infections

Answer 20

culture and microscopy

molecular techniques - ELISA with fungus specific antibodies, PCR

some bacteria can be similar to fungi thus important to differentiate

Question 21

Treatment

Answer 21

few effective anti-fungal