1
Q
What is the study of fungi?
A
Mycology
2
Q
Are fungi eukaryotes or prokaryotes?
A
Eukaryotes
3
Q
What do fungi include?
A
Yeasts, moulds, and fleshy fungi
4
Q
Is it true that fungi have adapted well to living on humans and animals?
A
Yes
5
Q
Are many fungi microscopic?
A
Yes, but not mushrooms
6
Q
What type of cell wall do fungi have?
A
A rigid cell wall
7
Q
What surrounds fungal cells?
A
A layered polysaccharide matrix
8
Q
What is meant by the fact that fungi are chemoheterotrophs?
A
Use organic carbon as an energy source
9
Q
What are the 2 types of fungi?
A
Saprophytes and parasites
10
Q
Saprophytes live off…
A
decaying matter
11
Q
parasites…
A
live off living matter
12
Q
Do fungi break down complex structures into smaller ones?
A
Yes
13
Q
Most of the diseases fungi cause are of the..
A
skin, hair, and nails
14
Q
A
lol
15
Q
Is it true that fungi produce toxins to damage the host?
A
Yes
16
Q
How many kingdoms of fungi are there?
A
2
17
Q
Describe the characteristics of a heterotrophic eukaryote
A
- Cells have nuclei
- Osmotrophic (absorb food)
- Diffuse, branched, tubular body (radiating hyphae)
- Reproduce by means of spores
18
Q
What are the 2 fungal kindoms?
A
- Eumycota and chromista
19
Q
describe eumycota
A
- “true fungi”
- use chitin to build their cell walls
- i.e Chytridiomycota, Zygomycota, Glomeromycota, Dikaryomycota
20
Q
describe Chromista
A
- pseudofungi
- have cellulosic hyphal walls and no chitin
- i.e Oomycota and Hyphochytriomycota
21
Q
Which fungi are of interest to us in this module?
A
The medically important fungal pathogens. There are thousands of fungi, but only a few are pathogenic to animals
22
Q
How many species of fungi are there?
A
Over 100,000
23
Q
How many species of fungi are animal pathogens?
A
Around 100
24
Q
Is it true that fungi play a major role in the recycling of nutrients?
A
Yes
25
Is it true that fungi are a major cause of food spoilage?
Yes
26
IS it true that fungi can destroy unpreserved wood and leather products?
Yes
27
- The overall incidence of serious fungal infection is low
- Some superficial fungal infections are quite common
- The overall incidence of serious fungal infection is low
- Some superficial fungal infections are quite common
28
What is the issue with the drugs that are used to kill fungal infections?
These drugs also kill eukaryotic cells in the body, so usually many side effects
29
What is a fungal infection called?
A mycosis
30
What are the major mechanisms of fungal disease?
- Allergic (hypersensitivity) reactions, where there is an immune response to specific fungal antigens
- Production of toxins, where mycotoxins and Aflatoxins may be produced
- Infection/mycosis
31
What is a mycotoxin
A fungal exotoxin
32
What is an aflatoxin?
poisonous, cancer-causing toxins made by Aspergillus molds that contaminate food crops.
33
is it true that fungal toxins can induce tumours in birds?
Yes
34
What are Dermatophytes?
Fungi that infect human skin
35
What are Thermal dimorphic saprobes?
fungi that live as molds in the environment but switch to yeast form at body temperature, allowing them to infect hosts.
36
Why are Thermal dimorphic saprobes diffuclt to control in terms of epidemiology?
Because they know how to survive in and out of the host
37
What are some examples of Thermal dimorphic saprobes?
Histoplasma capsulatum, Coccidioides immitis, Paracoccidioides brasiliensis
38
What are opportunistic saprobes?
Opportunistic saprobes are fungi that usually act as decomposers in nature, but when given the chance (like a weakened host), they can invade living tissues and cause infection.
39
Is it true that opportunistic saprobes mainly affect the immunosuppressed?
yes
40
Describe a Cutaneous (superficial) mycoses (infection)
- Affects the outer layers of the skin and causes an allergic reaction or an inflammatory response
41
Describe a subcutaneous mycoses (infection)
- Caused by fungi with low inherent virulence
- Infects host via a wound
- Remain localized or spread by direct mycelial growth
42
What are Systemic mycoses ?
Fungal infections that can affect multiple organs and often become widely disseminated in the host.
43
Give some examples of Cutaneous (superficial) mycoses disease
Ringworm
Athlete’s foot
Jock Itch
Candidiasis
44
Give some examples of Subcutaneous mycoses diseases
Sporotrichosis
Chromoblastomycosis
45
Give some examples of Systemic mycoses diseases
Cryptococcosis
Coccidioido-mycosis
Histoplasmosis
46
Systemic mycoses = fungal diseases that can affect internal organs, often acquired from the environment, and can be life-threatening in severe cases.
Systemic mycoses = fungal diseases that can affect internal organs, often acquired from the environment, and can be life-threatening in severe cases.
47
What are tinea?
related skin infections
48
What is the meaning of the disease tinea pedis?
Athlete's foot
49
What are cutaneous (superficial) mycoses caused by?
closely related dermatophytes that colonise and digest keratin
50
Why are cutaneous mycoses known as superficial?
- Because they affect only the outer, keratin-rich layers of the skin, hair, and nails.
- No living tissue is invaded
51
What fungus is dandruff cuased by?
Malassezia furfur
52
Are systemic mycoses actively pathogenic?
Yes
53
What is ringworm caused by?
Infections of Tinea pedis or Tinea capitis on the feet or scalp
54
How can ringworm spread through direct contact?
through a fragment of keratin containing viable fungus
55
How can ringworm spread through indirect contact?
floor of swimming pool/shower or combs, towels etc.
56
Why is the disease process of ringworm unique?
- no living tissue is invaded
- keratinised stratum corneum is simply colonised
- Can induce an inflammatory response in host.
- Type and severity of the host response related to species/strain of dermatophyte
57
What are the only fungi that depend on human/animal infection for the survival and dissemination?
Dermatophytes
58
Tinea pedis (athlete’s foot) infections...
- Dermatophytes (T. rubru) utilise keratin as a nutrient source
- Invade via enzymic digestion [keratinase] and mechanical pressure
- Usual cause - shedding skin scales containing viable infectious hyphal elements [arthroconidia]
- Scales can remain infectious for months or years
- Surfaces like carpet and matting make excellent vectors
59
What treatments can be used for athlete's foot?
- Topical therapy (i.e. creams applied directly to the skin)
- Oral triazole antifungals e.g. fluconazole (5-membered rings with 3 N-atoms)
- Prophylactic antifungal foot powder use reduces infection in swimmers
60
What is the mechanism of action of athelete's foor treatment Fluconazole?
Blocks ergosterol synthesis → damages fungal membrane
61
Describe yeast
- Unicellular fungi usually appear as oval cells
- 1-5 µm wide by 5-30 µm long.
- Facultative anaerobes
- Energy through aerobic respiration/fermentation.
- Thick polysaccharide cell wall
62
To protect against pathogens, what does the body usually detect?
- Pathogen-Associated Molecular Patterns (PAMPS)
- These are molecules that are unique to microorganisms, usaully cell wall components
63
What happens when the immune system detects yeast PAMPs?
- The innate immune defenses are triggered
- Inflammation, fever, and phagocytosis.
- Alternative complement and lectin pathways activated
64
What is candida albicans?
a normally harmless yeast that can become an opportunistic pathogen, causing infections ranging from mild thrush to life-threatening systemic disease.
65
What 2 ways does yeast reproduce?
By asexual and sexual reproduction
66
How does yeast reproduce by asexual reproduction?
- Budding
- Bud forms on outer cell as nucleus divides
- One nucleus migrates to elongating bud.
- Cell wall forms between bud and parent cell
- Bud breaks away.
67
What spores are produced in yeast sexual reproduction?
Ascospores
68
Describe yeast infections that are caused by Candida albicans
- Normal flora on mucous membranes and in gut
- Constrained by resident host microbes and defenses
- Infection often in Immunosuppressed, diabetics and women
- In women often expressed as Thrush/vaginitis
- Can lead to disseminated infections.
69
Vaginal candidiasis
- Common condition in women i.e if low pH levels
- Sexual activity and oral contraception may contribute
- Intense itching, burning/ soreness
- Production of a creamy white, curd-like discharge.
70
What are Allylamines?
- Antifungal drug class including Terbinafine
- Highly lipophilic in nature and tends to accumulate in skin, nails, and fatty tissues
- Effective but requires long treatment schedules (12-14 Months)
- Can cause liver damage!
71
What is the mechanism of action of Terbinafine?
- Affects ergosterol biosynthesis by inhibiting squalene epoxidase
(this enzyme helps create sterols needed for the fungal cell membrane).
72
What is the name of the fungus that casues oropharyngeal candidiasis (thrush)?
Candida albicans
73
What does thrush appear as?
white curd-like plaques (can be scraped off) in the oral cavity/ tongue
74
What are the symptoms of thrush?
burning, dryness, dysphagia, loss of taste, but can be asymptomatic
75
What is the presentation of Cutaneous candidiasis/ nappy rash
- Between the fingers or toes, or in the groin
- Common in infants i.e due to Irritation due to irregularly changed unclean nappies or chronic moisture
76
Describe the Subcutaneous mycoses, Chromoblastomycosis
- Chronic localised disease of skin and subcutaneous tissues
- Traumatic implantation of fungal elements into skin
- Chronic, slowly progressive and localised
- Rusted, warty lesions of limbs
- Wide distribution
- More common in bare footed populations in tropics
77
How is Chromoblastomycosis
diagnosed?
- Presence of brown pigmented, rounded sclerotic bodies with supporting clinical symptoms (skin scrapings and/or biopsy tissue)
78
How is Chromoblastomycosis treated?
- Surgical removal of tissue plus margin of uninfected tissue
- Use of drugs Fluorocytosine; thiabendazole; itraconazole
for 6 - 12 month period
-
79
Q: What is the classic presentation of sporotrichosis?
- A: Nodular lesions spreading along lymphatics (“sporotrichoid spread”)
80
81
Q: How is sporotrichosis acquired?
A: Traumatic implantation (e.g. rose thorn)
82
Q: What is the key advantage of sexual reproduction in yeast?
Genetic recombination
83
84
what is the subcutaneous mycoses, chromoblastomycosis, caused by ?
traumatic implantation (soil fungi)
85
what is the course of the subcutaneous mycoses, chromoblastomycosis?
chronic, slow, localised
86
What is the site of chromoblastomycosis?
usually lower limbs (barefoot exposure)
87
What do the lesions caused by chromoblastomycosis look like?
warty, verrucous (“cauliflower-like”) plaques
88
What is the epidemiology of chromoblastomycosis?
tropics, agricultural workers
89
“Mould in the cold, yeast in the heat”
“Mould in the cold, yeast in the heat”
90
What are some examples of opportunistic fungi that affect immunocompromised people?
Candidiasis
Aspergillosis
Cryptococcosis
91
Dimorphic cause systemic infections via inhalation!!!
Dimorphic cause systemic infections via inhalation!!!
92
In general, how can fungal pathogens be diagnosed?
- Microscopy (hyphae vs yeast)
- Culture
- Antigen tests
- Histology (e.g. “Medlar bodies”, capsules)
93
“Nodules along lymphatics” →
Sporotrichosis
94
“Warty cauliflower lesions” →
Chromoblastomycosis
95
“White plaques in mouth” →
Candidiasis
96
“Encapsulated yeast + meningitis” →
Cryptococcus
97
“Septate hyphae in lungs” →
Aspergillus
98
🧠 Final Big Picture
Think of fungi in 3 simple axes:
Where? (skin, subcutaneous, lungs, systemic)
Who? (healthy vs immunocompromised)
How? (inhalation vs trauma vs overgrowth)
🧠 Final Big Picture
Think of fungi in 3 simple axes:
Where? (skin, subcutaneous, lungs, systemic)
Who? (healthy vs immunocompromised)
How? (inhalation vs trauma vs overgrowth)
99
What is the cause of oropharyngeal candidiasis (thrush)?
candida albicans
100
What is the appearance of thrush?
White curd-like plaques that can be scraped off
101
What is the site of thrush?
buccal mucosa, tongue, oral cavity
102
What are the symptoms of thrush?
white creamy plaques
burning sensation
dryness
loss of taste
103
is it true that thrush can be asymptomatic?
Yes
104
Which type of women is vaginal candidiasis a common condition in ?
Women with low ph levels
105
What might contribute to vaginal candidiasis?
Sexual activity and oral contraception
106
What are the symptoms of vaginal candidiasis?
- Intense itching
- Soreness
- Production of creamy white, curd-like discharge
107
Ergot is the active compound of LSD. What is Ergot produced by?
Fungi
108
Is it true that candida albicans can lead to disseminated infections of the lungs, blood, heart, and the meninges?
Yes
109
Is it true that candida albicans causes ~10% of all cases of septicaemia?
Yes
110
Is it true that candida albicans is a normal flora on mucous membranes and in the gut that is constrained by resident host microbes and defenses ?
Yes
111
In women, what is candida albicans often expressed as?
Thrush/ vaginitis
112
What is Allylamine?
A synthetic antifungal agent
113
How is Chromoblastomycosis diagnosed?
Presence of brown pigmented, rounded sclerotic bodies, with supporting clinical symptoms (skin scrapings and/or biopsy tissue)
114
How is Chromoblastomycosis treated?
Treatment typically involves surgical excision of the affected tissue along with a margin of healthy tissue.
## Footnote
This approach helps to ensure complete removal of the infection and prevent recurrence.
115
What drugs are used to treat Chromoblastomycosis?
- Fluorocytosine
- Thiabendazole
- Itraconazole
116
What makes fungi eukaryotic?
The fact that they have a nucleus
117
is yeast unicellular or multicellular?
Unicellular
118
Is mould unicellular or multicellular?
Multicellular
119
What type of cell wall does chromista have?
A cellulose cell wall
120
What are the virulence featuers of candida albicans?
- Dimorphism (yeast ↔ hyphae)
- Pseudohyphae → tissue invasion
121
Is the adaptation of dimorphic fungi to be a mould in the environemnt and a yeast in the host a key virulence factor?
Yes
122
Do dimorphic fungi cause systemic infections?
Yes
123
What diseases can candida albicans cause?
- Thrush (oral candidiasis)
- Vaginal candidiasis
- Systemic infection (septicaemia)
124
Aspergillus is NOT always systemic, but becomes systemic in immunocompromised patients
Aspergillus is NOT always systemic, but becomes systemic in immunocompromised patients
125
What distinguishes infection by true pathogenic fungi from infection by opportunistic fungi?
True pathogenic fungi can infect healthy individuals, whereas opportunistic fungi usually infect immunocompromised hosts.
126
What is a key clinical feature of systemic fungal infections?
They can spread widely throughout the body, affecting multiple organs.
127
Microbial Pathogens
flashcards
Decks in class (10)
# Cards
-
Introduction and Environment164
-
Fungal Pathogens127
-
Lecture 3: Mycobacterial infection: Leprosy69
-
Lecture 4: Mycobacterial infection: Tuberculosis60
-
Lecture 5: Flagellated Protozoa: American Trypanosomes- Chagas Disease I90
-
Lecture 6 + 7: Flagellated Protozoa: American trypanosomes II + Flagellated protozoa: African trypanosomes (Tuesday 28th October)97
-
Lecture 8: African Trypanosome IIs49
-
Lecture 9: African trypanosomes45
-
Lecture 10: Malaria; Transmission and Epidemiology91
-
Lecture 11: Malaria Entomology and Vector Control65
