Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BS1040: Microbiology and Cell Biology > MC3-4: Eukaryotic microbial pathogens > Flashcards

MC3-4: Eukaryotic microbial pathogens Flashcards

1
Q

Define ‘facultative parasite’

A

An organism that lives and can complete its lifecycle independent of a host, but may occasionally be parasitic under certain conditions, e.g. when immunocompromised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define ‘obigate parasite’

A

A parasite that cannot lead an independent, non-parasitic existence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define ‘opportunistic parasite’

A

A parasite that takes advantage of certain opportunities to cause disease. Many lie dormant in the host until the immune system is reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the three ways in which a fungus can infect a human? Which are the most common?

A
  • Superficially (on the skin) – more common
  • Subcutaneously (under the skin) – less common
  • Systemically (multi-organ) – more common
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are dermatophytes?

How are dermatophyte infections acquired by humans?

Name two examples of dermatophyte infections.

A

Dermatophytes are moulds that grow on keratin (e.g. on the skin)

Infection is acquired from people, animals, or the environment, depending on the species

Examples of diseases: athlete’s foot, ringworm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why do dermatophyte infections cause a circular wound?

A

They eat the keratin and then move outwards when they run out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is candidiasis and what causes it?

A

Oral or vaginal thrush

Opportunistic Candida albicans following antibiotics and T-lymphocyte deficiencies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Define ‘commensalism’

A

A relationship between two organisms where one organism benefits from the other without affecting it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define ‘polymorphic’ and give an example of a polymorphic fungus.

A

An organism that can grow as both a yeast and as filamentous cells

e.g. Candida albicans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What percentage of humans are infected with Candida and where are the most common sites of infection?

A

80%

Intestine, colon, mouth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What percentage of women have had candidiasis and what is the most common cause?

A

75%

Following antibiotic treatments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How can Candida albicans be pathogenic if they are commensal?

A

If the host has low immunity or if there is a change in natural microbiota of physiology

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does Candida albicans cause disease?

A

It attacks the skin or mucosae and invades tissue by puncturing skin with its hyphae

If nutrient-rich environment, spores are produced and the population doubles in an hour

Biofilms can grow on implantable medical devices

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is Cryptococcus neoformans, what does it cause, and how is it acquired?

A

A yeast, causing chronic meningitis

Probably acquired from the environment, possibly pigeon droppings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does Pneumocystic carinii grow, what does it cause, and what is the route of infection?

A

Grows intracellularly

Produces serious pneumonia in immunocompromised

Route of infection uncertain, but endogenous and exogenous routes likely

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Define ‘endogenous’

A

When an organism already carries a pathogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Define ‘exogenous’

A

When an organism does not already carry a pathogen and acquires it from outside

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are Aspergillus and what do they cause?

A

Ubiquitous mould

Causing pulmonary and systemic infections, e.g. allergic aspergillosis (triggering asthma and COPD)

Can cause aflotoxin (a neurotoxin) and aspergilloma (lumps)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why are effective antifungal drugs hard to find?

A

Many drugs do not differentiate between fungi and humans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the three ways in which antifungal drugs work? Give examples of each type.

A
  • Cell wall integrity, e.g. nystatin, amphotericin B
  • Cell wall biosynthesis, e.g. fluconazole, itraconazole, miconazole, terbinafine
  • RNA synthesis: flucytosine (5-fluorocytosine)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What diseases can protoxoal pathogens cause in humans?

A
  • Malaria
  • Toxoplasma
  • Intestinal and vaginal infections
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Where are Naegleria found?

A

In warm fresh water, such as cooling towers in nuclear power stations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How does Naegleria affect humans?

A

Infects humans through their olfactory nerve (through the nose)

Ultimately causes a fatal brain disease
(primary amoebic meningoencephalitis or PAM/PAME)

Known as the brain-eating amoeba

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the life cycle of Naegleria?

A
  • Flagellate stage:
    • A small pear-shaped organism with two flagellae
    • Mobile
    • Stage that infects people who are exposed through water
  • Amoeba form:
    • ​Occurs after infection
  • Cyst stage:
    • ​Occurs in response to unfavourable environmental conditions
    • Resistant to harsh environmental conditions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Where are *Naegleria fowleri* usually found?
In warm-water environments
26
What is one of the most common amoebae found in soil, fresh water, and the natural environment?
*Acanthamoeba*
27
How big are *Acanthamoeba*?
15-35μm
28
Where are *Acanthamoeba* found?
In fresh water (e.g. contact lens solution) and salt water
29
How do *Acanthamoeba* affect humans?
* They infect humans through **contaminating contact lenses/contact lens cases** * Can also **infect broken skin** and cause cutaneous disease or even spread to the brain via the blood * Can also **infect the mucosa** and then the brain in a similar way to *Naegleria*
30
What is the life cycle of *Acanthamoeba*?
1. **Cysts** 2. **Trophozoite** (infective) 3. **Amoebae** which can enter humans in many ways
31
What diseases can *Acanthamoeba* cause?
* **Acanthamoeba keratitis (AK)** – eye disease * **Cutaneous amoebiasis** – skin disease * **Granulomatous amoebic ancephalitis (GAE)** – brain disease
32
What is acanthamoeba keratitis (AK)?
* **Progressive sight-threatening corneal disease** * Leading risk factor is **contact lens water** * **Most common type** of *Acanthamoeba* infection * Treatment is **not always successful** and corneal transplants often required * **Reactivation occurs if in transplanted cornea**
33
What are coccidia?
Obligate intracellular parasites that infect the intestinal tracts of mammals
34
What are common characteristics of coccidia?
Sexual cycle occurs in **epithelial cells** (gut in most species) Oocysts (infective stages) secretion after sexual cycle. Environmentally resistant
35
Define 'trophozoite'
The feeding stage of a protozoan parasite
36
Define 'schizogony'
The process of asexual reproduction during which the nucleus undergoes division preceding cell division
37
What are 'merozoites'?
The daughter cells produced by schizogony. They can develop into gametocytes or enter new host cells and undergo another cycle of schizogony
38
Define 'gameocyte'
Cells that are capable of developing into gamete. They are derviced from merozoites
39
*Cryptosporidium* were once thought to have many species. What is the current view?
They contain only a few species that have broad host specificity
40
What is the lifecycle of *Cryptosporidium*?
Direct faecal-oral life cycle with no intermediate hosts
41
Why did diseases caused by *Cryptosporidium* come to light in the 1980s?
A large number of AIDS patients were suffering from the disease
42
What is *Cryptosporidium parvum* and what are the symptoms of the disease it causes?
* A protozoan parasite that infects the intestine of the host * It is a problem in the young, old, and immunocompromised * Symptoms: * Diarrhoea (10-15 litres per day) * Abdominal cramps * Headache * Fatigue * Mild fever
43
Why are *Cryptosporidium* less accessible to factors that the host would normally use to control intracellular pathogens?
They live in an intracellular but extracytoplasmic location
44
What are *Cryptosporidium*'s unique features?
* **Parasite develops just under the host epithelial cell membrane** in an intracellular but extracytoplasmic position * The **oocyst stages are fully formed** when expelled from the host * There is **no need for sporulation** and therefore oocysts are **immediately infective** (auto-infection)
45
What is the common coccidian sexual life cycle?
* **Multiple rounds of schizogony** (depending on parasite species) * **Microgamete** (male) and **macrogamete** (female) form a **zygote** * **Oocysts can sporulate in host or externally**, depending on species
46
What is *Toxoplasma gondii*, how is it spread, and what are the symptoms in humans?
An **opportunistic parasite** Usually **asymptomatic** in adult humans Toxoplasmosis is usually spread by eating **poorly cooked food** that contains the cysts Can also contract it directly from **cats**
47
What are the different life cycles of *Toxoplasma gondii*?
* Takes place in the epithelium of the cats * Similar sexual cycle to *Cryptosporidium* * Direct (faecal-oral) life cycle can occur in cats
48
What is the life cycle of *Toxoplasma gondii* in an intermediate host?
* Any warm-blooded animal that **injests oocysts** can become **infected** * The parasite **does not undergo sexual multiplication** in the gut of intermediate hosts * Instead, it undergoes **asexual (extra-intestinal) multiplication in any cell of the host** as the **tachyzoite** **stage** for around 14 days * At 14 days post infection, the **tachyzoites transform into bradyzoites**. These form cysts in the muscle, brain, and eye * These cysts stages are long-lived and can i**nitiate the sexual cycle when eaten by a cat** or the **asexual cycle when ingested by any other carnivore**
49
Why are incidences of *Toxoplasma gondii* higher in pregnant women in Paris than they are in pregnant women in Glasgow?
Parisian women eat a lot of almost-raw meat
50
What are the differences in the *Toxoplasma gondii* symptoms in immunocompetent and immunocompromised humans, and congenital disease?
**Immunocompetenet** * Disease is usually slef-limiting but mild flu-like symptoms are common at onset * Cyst stages persist for life **Immunocompromised** * Disease commonly manifests as severe encephalitis * Due to a new infection or reactivation of cyst stages from historic infection **Congenital disease** * Women infected during pregnancy can transfer parasite to foetus * Congenital disease can be severe hydrocephalus, ocular lesions, mental retardation
51
What is the treatment for infections of *Toxoplasma gondii*?
* Sulphadiazine * Pyrimethamine * Spiromycin
52
What causes malaria?
The obligate parasite *Plasmodium*
53
How many cases of malaria were there in 2010? How many of these died?
* 219-550 million cases * 660,000 - 1.24 million deaths
54
Which species of *Plasmodium* infect man? Which is the most severe, and which is the most common?
* *P. falciparum* (most severe) * *P. vivax* (most common) * *P. ovale* * *P. malariae* * *P. knowlesi*
55
What does *Plasmodium* require?
Two hosts (obligate requirement)
56
How does malaria spread between hosts?
* **Female *Anopheles*** mosquite infected during **blood meal** * Male and female **gametocytes ingested** * **Sexual reproduction** occurs in stomach of mosquite * Infective **sporozoites accumulate** in the salivary glands of mosquito * Mosquito **injects sporozites into next host** during subsequent blood meal
57
Explain the geographic distribution of malaria infections.
* **Limited** but **extensive** geographic distribution * Dictated by **natural habitat of** ***Anopheles*** host * **Population density**, prevalence of **childhood infection**, ambient **temperature** and **rainfall** all play an important role * **80%** of cases originate from **sub-Saharan Africa**
58
What are the differences between *P. falciparum* and *P. vivax* infections?
***P. falciparum*** * Potentially fatal – cerebral malaria * Very high parasitaemia * Drug resistance ***P. vivax*** * Common, usually benign * Recurrent
59
How can malaria be managed and controlled?
* **Diagnosis** by microscopy of blood films * **Treatment** with **chloroquine** or **quinine** (++) * **Eradicate liver forms** in *P. vivax* * **Prophylaxis** for travellers * **Avoid mosquito bites** * Mosquito **control** * ?**Vaccination** – trying to develop
60
Give a brief overview of the current state of malaria research.
* Malaria **funding has increased** nearly 10-fold * Major gains have been made in **controlling** **the** **disease** in developing nations * Through interventions, including **timely diagnosis and treatment**, improved **diagnostics**, effective **drugs**, indoor spraying with long-lasting **insecticides**, bed nets treated with long-lasting insecticides * Current tools and treatments are **insufficient to achieve elimination** in many countries * Cost of maintaining these interventions is **billions of dollars a year** * Malaria **parasite is developing resistance** * Infected individuals who are **asymptomatic** remain an ongoing source of transmission * Microbiome impacts on mosquito gut

BS1040: Microbiology and Cell Biology (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions