Microbiology Fungi And Parasites L17

Question 1

What is the study of fungi called

Answer 1

Mycology

Question 2

What type of cells are fungi and whats different about them compared to other cells

Answer 2

Eukaryotic but dont contain cholorophyll but have cell
walls, filamentous structures,
and produce spores

Question 3

Examples of fungi species

Answer 3

Moulds, yeasts (single celled) and higher fungi

Question 4

What are filamentous structures formed by fungi called

Answer 4

Hyphae

Question 5

What is a colony of hyphae referred to as

Answer 5

Mycelium

Question 6

What are cross walls in hyphae called

Answer 6

Septa/septum

Question 7

3 types of mycotic diseases

Answer 7

1) Hypersensitivity - an allergic reaction to moulds and spores
2) Poisoning due to fungal toxins
3) infections

Question 8

4 most common classification of fungal infections

Answer 8

1) Superficial mycoses
2) Subcutaneous mycoses (located at or below the epidermis)
3) Systemic mycoses (affecting the whole system)
4) Opportunistic mycoses (infections with organisms of low virulence)

Question 9

Examples of systemic mycoses and how they infect us

Answer 9

• Aspergillus
• Pneumocystis Carini

Systemic mycoses can occur due to inhaled fungal spores or deep trauma

Question 10

How are fungal diseases treated and what effects do they have on the host

Answer 10

membrane sterols or ergosterols are targeted however most substances which may impair the invading fungus will usually have serious side effects on the host

Question 11

What is a parasite

Answer 11

An organism that obtains food and shelter from another organism and derives benefits from this association

Question 12

What is a vector

Answer 12

An organism (usually an insect) that is responsible for
transmitting the parasitic infection is known as the
vector

Question 13

What are the classifications of parasites

Answer 13

1) protozoa
2) helminths
3) arthopods

Question 14

What are protozoa

Answer 14

Diverse groups of unicellular microorganisms about 5 um to 1mm. Most live in water and are parasites of a range of species

Question 15

How do protozoa move

Answer 15

They have mechanisms of locomotion via flagella or pseudopodia

Question 16

Protozoa can be divided into groups based on their motility, what are they

Answer 16

Mastigophora

Sarcodina/Rhizopodia (e.g Acanthamoeba)

Sporozoa (e.g toxoplasma)

Ciliata

Question 17

How can protozoa survive for a long time without food supply

Answer 17

They can form cysts, which reduces their metabolic rate

Question 18

What are Acanthamoeba and where can they be found

Answer 18

Free living amoebae and found almost everywhere, most prevalent in soil, fresh water and other habitats

Question 19

What type of pathogen is Acanthamoeba

Answer 19

Opportunistic or non-opportunistic pathogen

Question 20

What disease can be caused by Acanthamoeba

Answer 20

1) Granulomatous amoebic encephalitis (inflammation of the brain)
2) Disseminated granulomatous amoebic disease (eg, skin, sinus, and pulmonary infections)
3) Amoebic keratitis (1-33 cases per million CL wearers)

Question 21

What are the 2 stages of the life cycle of acanthamoeba

Answer 21

1) an actively feeding stage referred to a trophozoite which feed on bacteria, yeast, algae and cells
2) a dormant cyst

Question 22

How does Acanthamoeba detect its prey

Answer 22

Through chemotaxis

Question 23

What is special about toxoplasma

Answer 23

Vast majority of people infected will not have noticed any symptoms

Lifecycle can only be completed in cats (definitive host) that excrete resistant oocysts in their faeces

Question 24

How does toxoplasma infect people

Answer 24

Oocysts (eggs) can infect by either directly by ingesting substances contaminated with cat faeces or indirectly by ingesting undercooked infected meat of species which have themselves become infected from cats

Question 25

3 groups that helminths can belong to

Answer 25

1) Nematodes (round worms)
2) crestodes (tapeworms)
3) Trematodes (flukes)

Question 26

What is toxocara and how does it infect us

Answer 26

Toxocara canis is a round worm parasite of dogs and foxes and humans (usually children) acquire T. canis eggs by ingesting soil, by direct contact with dogs or by consumption of uncooked food food contaminated by eggs, transmitted by flies

Question 27

What are some clincial syndromes of toxocara

Answer 27

1) Visceral toxocarisis - caused by the migration of larvae through the internal organs of humans and the resulting inflammatory reaction
2) Ocular toxocariasis — migration of larva into the posterior segment of the eye, tends to occur in older children and young adults. Patients may present with decreased vision, red eye, or leukocoria (white appearance of the pupil)

Question 28

What is ochocerca and which part of the world is it common in

Answer 28

Onchocerciasis is endemic within the river basins of West and Central Africa and is the most frequent ophthalmic worm infection

Question 29

Who are the hosts for ochocerca

Answer 29

The black fly is the intermediate host, which also acts as the vector and humans are the definitive host

Question 30

What are the ocular manifestations of ochocerca

Answer 30

• Keratitis
• Irdocyclitis
• Retinitis
• Optic atrophy