Fungal and Protozoan Diseases Flashcards
(158 cards)
1
Q
What kind of organisms are fungi?
A
Eukaryotic organisms
2
Q
What do fungi comprise?
A
- Yeasts
- Moulds
- Higher fungi
3
Q
What kind of organisms are yeasts?
A
Single celled
4
Q
What are moulds?
A
Filamentous fungi
5
Q
What are higher fungi?
A
Mushrooms and toadstools
6
Q
What survival advantage do fungi have?
A
They can survive in an environment where nutrients are limited
7
Q
What are saprophytes?
A
Organisms that live off dead organic matter in soil and water.
Many fungi are saprophytes
8
Q
What are the main forms of fungal growth?
A
- Yeast like growth via simple budding
- Mould-type growth
9
Q
What does yeast like growth allow for?
A
Growth in the simplest form
10
Q
What can some yeast form?
A
Pseudeohyphae
11
Q
How do yeasts that form pseudohyphae grow?
A
Buds elongate to form filaments
12
Q
What happens in mould-type growth?
A
Numerous microscopic, branching, filamentous hyphae are produced to form extensive arrangement of mycelia
13
Q
What is the purpose of mycelia?
A
They are used to gain nutrients and reproduce
14
Q
What do reproductive mycelia do?
A
Produce spores
15
Q
How do reproductive mycelia produce spores?
A
Either sexually or asexually
16
Q
What do the spores produced by mycelia do?
A
Disseminate throughout the atmosphere and colonise new environments
17
Q
What do mycelia look like?
A
18
Q
What is meant by dimorphic growth?
A
It will invade a tissue in its yeast form, yet form a mould in the living environment
Fungi can, and commonly do, grow in this manner
19
Q
What is the exception to the dimorphic growth of fungi?
A
Candida spp.
20
Q
How does Candida spp. grow?
A
It stays in its yeast form except for producing pseudohyphae
21
Q
On what basis can fungi be classified?
A
- Degree of tissue involvement
- Mode of entry into the host organisms
22
Q
What are the classifications of fungi?
A
- Superficial
- Subcutaneous
- Systemic
- Opportunistic
23
Q
What is meant by superficial fungi?
A
Localised to hair, skin, and nails
24
Q
How common are subcutaneous fungi?
A
Rare
25
What is meant by systemic fungi?
Deep infections of internal organs
26
When are opportunistic fungal infections seen?
Only in immunocompromised individuals
27
Give 5 examples of fungi that can be superficial
* Dermatophytes
* Candida
* Apergillus
* Cryptococcus
* Pneymocystitis
28
Give 4 examples of fungi that can be systemic
* Candida
* Apergillus
* Cryptococcus
* Pneumocystitis
29
Give 4 examples of fungi that can be opportunistic
* Candida
* Apergillus
* Cryptococcus
* Pneumocystitis
30
How common are fungal infections in the UK?
Most fungal infections are uncommon to healthy individuals, except for candiasis or dermatophyte infections, which are quite common
31
What are dermatophytes?
Superficial fungi that grow on keratin
32
Where are dermatophytes mainly seen?
On skin or hair
33
How can infection from dermatophytes be acquired?
From people, animals, or the environment, depending on the species
34
What are the main species implicated in dermatophyte infection?
* Epidermophyton
* Microsporum
* Trichophyton
35
How do dermatophyte infections commonly present?
Ringworm
36
What is ringworm?
Red scaly patches that spread out that are itchy, but rarely painful
37
On what basis are dematophyte infections clinically labelled?
By their sites of infection
38
What are the clinical labels of dermatophyte infection?
* Tinea Capitis
* Tinea Corporis
* Tinea Pedis
39
Where does Tinea Capitis affect?
Head and neck
40
Where does Tinea Corporis affect?
Trunk
41
What is Tinea Pedis?
Athlete's foot
42
Where are candida species found?
Widely distributed in the environment
43
What do the candida species form part of?
The normal commensal population in the GI tract, skin, and female genital tract
44
What is the result of candida species forming part of the normal commesnal population?
Following the use of broad spectrum antibiotics, a fungal growth may develop
45
*Other than antibiotics,* how else may a fungal growth develop?
As a result of any immune deficiency
46
What do yeast fungi contain?
Pseudohyphae
47
What are most fungal infections caused by?
Candida Albicans
48
What does candida cause?
Oral and vaginal thrush
49
What happens in oral and vaginal thrush?
Creamy, curd-like plaques are produced
50
What do the plaques in thrush cause?
Pain and itching
51
Who can develop a systemic infection from Candida spp.?
Individuals who suffer from neutropenia
52
Why can Candida infection not be diagnosed by growth on laboratory media?
As they are part of the normal commensal flora, the growth on laboratory media can prove inconclusive
53
How can Candida infection be viewed?
Microscopy
54
What should any results of Candida infection investigation be determined in relation to?
The clinical picture
55
Who is at risk of developing opportunistic fungal growth?
* Immunocompromised
* Metabolic defects
* Undergone surgery
56
What fungi can grow opportunistically?
* Aspergillus spp.
* Cryptococcus
* Pneumocystis jiroveci
57
When can candiasis develop systemically?
* In severely immunocompromised individuals
* Following chemotherapy
58
What are aspergillus spp.?
Ubiquitous saprophytic fungi
59
What can aspiration of aspergillus spores give rise to?
Type III hypersensitivity reaction *(Farmers lung)*
60
What can become colonised by aspergillus?
Healed old cavities or bronchiectasis
61
What is caused when healed cavities or bronchiectasis are colonised by aspergillus?
Aspergilloma
62
What can happen in aspergillus infection in neutropenic patients?
They begin in the lung, and can develop into disseminated systemic disease
63
How can aspergillus infections be diagnosed?
* Broncholavage
* Antibody detection
64
How can aspergillus infections be treated?
Using anti-fungals
65
What is cryptococcus?
A saprophyte that infects humans
66
Where is cryptococcus commonly found?
In pigeon faeces
67
What is the main species of the cryptococcus genus?
Cryptococcus neoformans
68
What is cryptococcus neoformans associated with?
Subacute or chronic form of meningitis
69
What does meningitis caused by cryptococcus neoformans result from?
Inhalation of the species
70
In whom does pneumocystis jiroveci cause infection?
**Only** patients with severe T-cell dysfunction
71
Why may someone have severe T-cell dysfunction?
* HIV
* Malnutrition
* Primary immune deficiencies
* Immunosupressive drugs
72
What kind of fungus is pneumocystis jiroveci?
Yeast-like
73
How is pneumocystis jiroveci transmitted?
Via the respiratory route
74
How do patients with pnuemocystis jiroveci present?
* Progressive dyspnoea
* Unproductive, dry cough
75
What does pneumocystis jiroveci cause?
Pneumocystsis pneumonia (PDP)
76
What happens in PCP?
* Pulmonary consolidation
* Decreased pO2
77
How can pneumocystis jiroveci be diagnosed?
* Bronchiolavage
* Immunoflourescence
78
What is the result of fungi being eukaryotes?
They share a similar cellular structure to human cells
79
What is the result of fungi sharing a similar cellular structure to human cells?
Any anti-fungals used have the potential to cause damage to our own cells
80
What are the main types of anti-fungals commonly used?
* Azoles
* Terbinafine
* Polyenes
* Echinocandins
81
What do azoles do?
Block the action of cytochrome C450
82
What does the type of azole given depend on?
The fungus in question
83
Give 4 types of azole
* Fluconazole
* Itraconazole
* Vorixonazole
* Flucystosine
84
What does terbinafine do?
Inhibits squalene epoxidase with resultant accumulation of aberrant and toxic sterols in the cell wall
85
What do polyenes do?
Forms a pore in the fungal membrane
86
What do echinocandins do?
Inhibit the synthesis of 1,3-ß-glucan
87
What is 1,3-ß-glucan?
A molecule in the cell wall of pathogenic fungi
88
What are protozoan?
Single celled eukaryotes
89
How do protozoan differ from fungi?
In their cell walls and life cycle
90
What are the main two protozoan worldwide?
* Toxoplasmosis
* Malaria
91
What is the prevalence of toxoplasmosis?
1-2billion
92
What is the prevalence of malaria?
200-300million
93
How can the life cycles of protozoan be classified?
* Simple
* Complex
94
Give two examples of a protozoa with a simple life cycle
* *Entamoeba*
* *Giardia*
95
Give two examples of protozoa with complex life cycles
* *Plasmodium*
* *Toxoplasma*
96
Draw a diagram illustrating the simple life cycle of a protozoa
97
Draw a diagram illustrating the complex life cycle of a protozoa
98
What is a trophozoite?
The active protozoa which is mitotically dividing constantly
99
What is the cyst?
The non-replicating, resistant form of the protozoa
100
What are the eggs in the complex life cycle seen to be?
The infectious form of the protozoa
101
What are the main groups of protozoa?
* Amoebae
* Flagellates
* Apicomplexa
102
What are the simplest forms of protozoa?
Amoebae
103
What are amoebae characterised by?
A feeding and dividing trophozoite
104
How can amoebae survive in most environments?
They can form a resistant cyst
105
What form do flagellates have?
A trophozoite form with a flagella attached
106
What is the purpose of flagellates flagella?
Locomotion
107
Give an example of a flagellate
Giardia
108
What are apicomplexa?
Protozoa that are intracellular, and have a sexual and asexual reproduction life cycle
109
Give two apicomplexa
* Toxoplasmosis
* Malaria
110
Give 3 types of protozoa that affect humans to cause disease
* Entamoeba histolytica
* Giardia lambia
* Cryptosporidium
111
What does entamoeba histolytica infect?
The large intestine
112
How are entamoeba histolytica transmitted?
By faeco-oral route
113
How do entamoeba histolytica infect the large intestine?
They adhere to the intestinal epithelium
114
What can entamoeba histolytica lead to?
* Dysentry
* Brain or liver abscesses
115
Is giardia lamblia common worldwide?
Yes
116
How is giardia lamblia transmitted?
In the water and food supplies
117
What allows giadia lamblia to be transmitted in the food and water supplies?
Poor sanitiation
118
What path do giardia lamblia take in the human body?
They divide in the jejenum, then adhere to the intestinal walls
119
How do giardia lamblia divide?
By binary fission
120
How do giardia lamblia adhere to the intestinal wall?
By sucking discs
121
What do giardia lamblia form that allows their transmission to the environment?
Cysts in faeces
122
What are the symptoms of giardia lamblia?
* Abdominal pain
* Flatus
* Bulky, fatty stools
123
Why does giardia lamblia infection cause bulky, fatty stools?
Due to poor fat absorption
124
What kind of protozoa is cryptosporidium?
Zoonotic
125
How is cryptosporidium transmitted?
By farm animal contact
126
Who is cryptosporidium infection common in?
Children and immunosuppressed individuals
127
What are the symptoms of cryptosporidium infection?
Self-limiting watery diarrhoea with abdominal cramps
128
How does cryptosporidium produce its symptoms?
The protozoa interferes with the sodium pumps in the small intestine
129
What causes malaria?
Four species of the genus plasmodium;
* P. Falciparum
* P. Vivax
* P. Ovale
* P. Malarie
130
How many people live under the treat of malaria?
More than 1.5 billion people
131
How many children under the age of 5 years die in Africa each year from malaria?
1 million
132
How does malaria get into the body?
The oocytes of plasmodium *(sporozoa)* are injected into the circulation of individuals by the female Anopheles bites
133
What happens to the malaria parasites once they are inside the body?
They multiply in the hepatocytes in the liver before invading the red blood cells and multiplying
134
How are the systemic features of malaria caused?
The plasmodium provoke the release of cytokines from the red blood cells
135
How are plasmodium spread to other cells from RBCs?
They cause the lysis of the erythrocytes and so can spread to other cells, *producing very large numbers*
136
What happens to the malaria infected erythrocytes?
They can adhere to the endothelial wall, causing cerebral malaria
137
How can malaria be transmitted from an infected individual?
The plasmodium protozoa differentiate into the sexual stage and can be taken up by another biting female Anopheles, and develop in the mosquito gut before migrating to the mosquitos salivary glands
138
Between that do the symptoms of malaria vary?
* Individuals
* Plasmodium species
139
What are the symptoms of malaria?
* Shaking
* Fever
* Anaemia
* Pre-hepatic jaundice
* Dark pigmented urine
140
Why is dark pigmented urine a symptom of malaria?
From erythrocyte destruction
141
What secondary pathologies can malaria cause?
* Cerebral malaria
Hepatospleenomegaly
142
What is the most fatal malaria species?
Plasmodium Falciparum
143
What is the most common malaria species?
Plasmodium Vivax
144
What is plasmodium Vivax known to do?
Reoccur from latency
145
What does treatment for malaria involve?
* Chemotherapy
* Quinine
146
What is the purpose of chemotherapy in malaria treatment?
To destroy the parasites
147
What is the best means to reduce malaria cases?
Prevention
148
How is malaria prevented?
* Use of mosquito nets while sleeping
* Prophylaxis regularly taken
149
Draw a diagram illustrating the cycle of malaria
150
What causes toxoplasmosis?
The protozoan toxoplasmosis gondii
151
Where does toxoplasmosis gondii have its life cycle?
In cats
152
What can toxoplasmosis gondii infect?
All warm blooded mammals
153
How can humans become infected with toxoplasmosis gondii?
* Through ingestion of the oocytes from cat excrement contaminating food
* Can spread vertically to foetus
154
What does toxoplasmosis cause in the primary infection?
Flu-like symptoms
155
Who is toxoplasmosis a problem for?
Immunocompromised individuals
156
Why is toxoplasmosis a problem for immunocompromised individuals?
Because toxoplasmosis gondii persists inside the host cell for very long periods, yet falling immunity can allow for reactivation
157
Where can toxoplasmosis spread to?
The brain
158
What is the result of toxoplasmosis spreading to the brain?
* Cerebral abscesses
* Encephalitis
