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Fungi, Parasite Flashcards

1
Q

For fungi,
What is the cell wall made of

What is the cell membrane made of

Does it has a cytoplasm and nucleus?

A

Glucan, protein, Chitin

Phospholipid, ergosterol

Yes

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2
Q

What are the 3 classifications of fungi

A

Yeast, Moulds, Dimorphic fungi

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3
Q

For yeast

What’s the size

Is it unicellular/ multicellular

How does it divide

Name 2 example

A

5 micrometer in diameter

Unicellular

By budding

Candida albicans
Cryptococcus neoformans

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4
Q

For mould

What is the

Unicellular/ Multicellular

Size?

Does it form globular/ filament? What is the product formed

How does it reproduce

Name 2 subdivisions

A

Multicellular

2-4 micrometer wide

Filament. Hyphae–> Mycelium

By spore, via sexual/assexual reproduction

Aspergillus fumigatus

Dermatophytes
‐ Trichophyton, Epidermophyton, Microsporum

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5
Q

For dimorphic fungus

What determine the form

Name the forms and the criteria

Example?

A

Temperature

Yeast: 37 degree Celsius
Mould: 25 degree Celsius

Penicillium marneffei, aka Talaromyces marneffei

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6
Q

Name 3 global fungi

Name 1 local fungi

Neutropenia is the risk factor for what

HIV is the risk factor for what?

A

Candida, Dermatophytes, Aspergillus

T. marneffei

Aspergillus

C. neoformans, T. marneffei

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7
Q

What fungi causes infection/problem in immune competent host?

A

uncommon, but some can be allergic to the spores

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8
Q

What fungi causes infection in immunecompromised host?

A

Systemic candidiasis (ie by Candidas)
Cryptococcus neoformans
Aspergillus fumigatus
Talaromyctes Marneffei

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9
Q

What are the 4 classes of antifungal drug

What is their mechanism

A

Polyenes: complex with ergosterol to disrupt the fungal plasma membrane

Azole: inhibit ergosterol synthesis

Nucleoside analogues (as DNA polymerase inhibitor, reduce DNA synthesis and viral replication)

Echinocandins: Cell wall synthesis inhibitors

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10
Q

Name an example for

Polyenes

Azoles

Nucleoside analogues

Echinocandins

A

Nystatin, amphotericin B

Fluconazole, itraconazole, voriconazole,
posaconazole

5-flucytosine

Caspofungin, micafungin, anidulafungin

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11
Q

What stain do we use to visualize

Mould

Candidas

Cryptococcus neoformans

What is the method to visual ALL fungi’

What is the culture used

A

KOH

Gram Stain

Indian ink stain

Biospy (ie obtain sample)
Histopathology (ie observe sample)

Agar and broth culture

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12
Q

Name the component of cell walll that is detected in antigen testing to detect virus

What is the antigen we use for C.neoformans

What is the antigen we use for Aspergillus

Name another method to detect Aspergillus

What do we look for Patient’s response
Name a fungi that can use antibody detection

A

Beta-D-glucan

Capsular polysaccharide

galactomannan

Nucleic acid detection

Antibody detection
Biospy and histopathology

T. marneffei

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13
Q

Is Candida albican

A yeast/mould/dimorphic fungi

Name 3 important species

What is the host defense against it

A

Yeast

－C. parapsilosis
－C. tropicalis
－C. krusei

－Intact skin
－Neutrophils, monocytes

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14
Q

For Candidas albican

What is the reservior

Is it local/global?

What are the 8 risk factors for that

A

Skin, GI tract, female genital tract

Global

－Broad spectrum antibiotics:
selective pressure
－Hospitalization
－ICU
－Intravenous lines
－HIV (suppressed Immune system)
－Neutropenia (Low neutrophll count)
－Transplant (use of immune suppressor)
－Steroid (same as above)

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15
Q

What can Candidas albican cause

In immune competent host

In immunocompromised host

A

－Vaginal thrush

Refractory superficial infections
－Oral thrush
－Mucocutaneous candidiasis

Systemic candidiasis
－Candidemia: one of the major causes of nosocomial blood
stream infection
－Disseminated infection: Eye, skin, kidney
－Hepatosplenic candidiasis
－Any organ

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16
Q

How do we diagnosize the Candida albicans

By visualization?

By culture

By Antigen detection?

A

With gram stain

－Agar plates e.g. pus
－Broth culture e.g. blood
－Germ tube formation in serum, biochemical tests

Serum: -D-glucan

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17
Q

How do we treat

Superficial candidiasis

Systematic candidiasis?

A

Topical treatment (e.g. nystatin)
－Systemic treatment in refractory cases (e.g. fluconazole)

－Systemic treatment
－Fluconazole, amphotericin B

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18
Q

Why shld we prevent Candida albicans by avoid antibiotics overuse

What drug do we use to prevent? In what situation?

A

It prevents overgrowth of fungi due to disrupted flora and microbiome

Fluconazole prophylaxis for transplant recipients

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19
Q

Can we avoid exposure and do vaccination

A

No

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20
Q

What is the defintion of Parasitism

A

any reciprocal association in which a species depends upon another for its existence.

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21
Q

What is the defintion of a parasite

A

the species that derives all the benefit from the association.

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22
Q

What is the host

A

the harbouring species

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23
Q

What is the word infection and infestation in parastie

A

Infection: Invasion of endoparasites

Infestation: External parasitism by ectoparasites

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24
Q

How can we classifiy parasite according to their

Dependence on host

Temporal relationship with host

Physical relationship with host

A

obligatory (complete dependence) or facultative

temporary or permanent

ectoparasite or endoparasite

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25
How can we diagnosize parasitic infecion by demostrating parasitic in appropriate specimen? If we detect antigen/antibody in blood/other body fluid, what is it called What parasites will we culture and is it common? If we wanna dianosis via nucleic acid, what have to be done
direct microscopic examination, staining, or tissue sections Serology Protozoa PCR
26
What are the 5 means to prevent parasite
Eliminate/reduce number of Parasite in reservior Vector Avoid exposure to parasites and/or vector Chemoprophylaxis (ie chemoprevention) Vaccines
27
How do we classify endoparasites Name the 2 smaller groups
Single-celled: Protozoa Mutlicellular: Helminths
28
For Protozoa, how do we subdivide them according to the site of infection
Lumen-dwelling (luminal) protozoa and Blood and tissue (extraluminal) protozoa
29
For ectoparasites, what is it
arthropods that live in or on other animals (ie, their hosts) and obtain shelter and nourishment from them.
30
Name 4 example of protozoa
Entamoeba histolytica Cryptosporidium spp. Trichomonas vaginalis Plasmodium
31
Which protozoa cause liver damage What type of protozoa is it What exactly does it cause What is the infectious form and what is the active form How does it reach the extraintestinal abscesses
Entamoeba histolytica Luminal Causes amoebic colitis/dysentery and amoebic liver abscess. Cyst. Trophozoite It invades the colon wall and multiplies and reach the organs via circulation
32
Which protozoa cause water-borne infection What type of protozoa is it What exactly does it cause
Cryptosporidium spp. Luminal Causes diarrhoea in the immunocompetent hosts, but potentially severe infection in the immunocompromised individuals
33
Which protozoa is the cause of common Sexual-transmitted infection What kind of protozoa is it Does it form cyst What is the infectious stage of Trichomonas vaginalis
Trichomonas vaginalis Luminal No Trophozoite
34
Name the one causing Malaria What type of protozoa is it Name 5 main species underneath What is the majority of case caused by
Plasmodium Extraluminal Plasmodium vivax Plasmodium falciparum Plasomodium malariae Plasmodium ovale Plasmodium knowlesi Plasmodium vivax Plasmodium falciparum
35
For malaria, what is the Natural Vector Other mean of transmitting What is the meaning of vertical transmission
female Anopheles mosquitoes Blood transfusion and organ transplantation Contaminated needles/medical instruments and medications Mother to unborn infants before or after delivery
36
What is the life cycle of Plasmodium
Infection. 2. Pre-erythrocytic cycle. 3. Erythrocytic cycle. 4. Secondary schizogony in hepatocytes 5. Transmission to Anopheles.
37
What is the form of Plasmodium in infection What cell will it enter? In what amount of time? What is the vector?
sporozoites Hepatocytes. Half an hour Mosquito
38
In pre-erythrocytic cycle, where are they located What are they doing inside
Hepatocytes Assexual production of exo-erythrocytic merozoites in hepatocytes. as well as infecting other hepatocytes and releasing more merozoites to blood
39
What does they do in Erythrocytic cycle. What does the term Schizogony mean What is the term Gametogony mean
Invading circulating RBC formation of merozoites in infected RBC; infection of new RBC. Formation of male and female gametocytes (micro- and macro- gametocytes), then uptaken by female Anopheles mosquitoes
40
Where is the Secondary schizogony taking place Which 2 class will develop into what
In hepatocytes P vivax and P. ovale into hypozoites
41
What will the plasmodium undergoes when it is uptaken by the vector
The gametocytes forms the gametes The microgametes enter the macrogametes and forms ookines then oocyst. It will then burst to release the sporozoites
42
Is there any specific symptoms for uncomplicated malaria
No
43
For severe malaria, what happens
End-organ damage
44
Is there any specific fever pattern for malaria Does it always exist
Yes No
45
What is relapse in Malaria
recurrence of symptoms after complete initial clearing of parasitaemia due to re- invasion of bloodstream by exo-erythrocytic stages (hypnozoites).
46
What is recrudescence in Malaria
recurrence of symptoms after initial parasitaemia is reduced to a very low level but not completely cleared.
47
What is the pathogenesis, in other words, how does it cause problem for Malaria
1. Increased destruction of erythrocytes due to: * Decreased deformability of RBC. * Infection by parasites (P. falciparum infects both reticulocytes and mature RBCs) * Increased clearance in splenomegaly. 2. Cytoadherence in P. falciparum infection (adhesion of infected RBC to endothelial cells) resulting in microvascular obstrucon. 3. Lysis of RBC resulting in iron depletion, anaemia, haemoglobinuria (hence the name of blackwater fever) 4. Immune complex deposition in kidneys resulting in nephrotic syndrome (in chronic infections due to P. malariae). 5. Release of inflammatory cytokines during the course of infection.
48
What is the most severe form of Malaria What are it's characteristics
Falciparum malaria Invades RBC of all ages. * High levels of parasitaemia. * Highest mortality. * Microvascular obstruction.
49
What shld we ask when suspecting malaria
Travel history
50
Name 3 therapy for malaria and their underlying principle
chemoprophylaxis: destroys asexual erythrocytic stages to prevent development of clinical symptoms. **Preventive measure Clincal cure: blood schizonticidal --> Killing infected RBC at all stages Radical cure:Tissue schizonticide --> targets at elimination of the gametocytes and hepatic resting stages (hypnozoites of P. vivax and P. ovale)
51
Can chemoprophylaxis protect malaria completely? When shld the antimalarials be intaken
No Before, during and some days after going to an endemic place
52
What is the 5 methods to prevent and control malaria
1. Vector control; e.g. reducing breeding sites of mosquitoes. 2. Avoidance of exposure; e.g. use of insect repellents. 3. Treatment of cases 4. Chemoprophylaxis 5. Vaccines are now available, but they do not confer 100% protective efficacy, and currently not used for general protection of the whole population or travellers.
53
What are the symptoms of malaria
1. Paroxysms. * Chills and rigor for 1–2 hours, followed by spiking fever in the next few hours. * Marked sweatng and defervescence with a rapid drop in temperature. * Note that in real life, patients usually do not present with the typical periodic fever paterns. 2. Severe malaria (usually in P. falciparum, and occasionally P. vivax): characterized by end organ damage, e.g. cerebral malaria, severe anaemia, renal failure, circulatory shock, hypoglycaemia, etc.
54
What is the fever pattern of malaria theoretically
* P. vivax, P. ovale, P. falciparum: 48-hour cycle. * P. malariae: 72-hour cycle. * P. knowlesi: 24-hour cycle.
55
How can we diagnosize Malaria
1. History: travel history, fever patern (not useful in most clinical cases), prophylaxis taken, blood or blood product transfusion, etc.. 2. Specimens: peripheral blood, an􀆟coagulated with EDTA. 3. Thick and thin blood films stained with Giemsa, Wright, or Field’s stain. 4. Single nega􀆟ve blood smear does not rule out malaria. 5. Other diagnos􀆟c tests: an􀆟gen detec􀆟on in peripheral blood, nucleic acid amplifica􀆟on
56
For Helminths, what are the 3 subdivisions
nematodes, trematodes, cestodes
57
What is nematodes What can it be subdivided into
Round worms Intestinal nematodes and blood and tissue nematodes
58
Which one is usually asymptomatic for immunocompetent host but cause problem for immunocompromised host What problem can it cause What can cause complication What type of nematodes is it Why will it cause pneumonia
Strongyloides stercoralis Hyperinfection and disseminated infection (infection due to a far away origin) bacterial sepsis Intestinal nematodes It brings bacteria from the large intestine to the lungs
59
Which nematode is common in cosmopolitan infection What does it cause What form is it intaken How does it cause the symptom
Enterobius vermicularis perianal pruritis embryonated egg At night, the female Enterobius vermocularis will travel to perianal region to lay eggs The movement
60
What Nematode cause meningitis Where is it usually present Where is it present before it infects human How does it leave the first host What is the role of the snails and slugs. etc
Angiostrongylus cantonensis Present in high risk food raw or undercooked snails and slugs, freshwater shrimp, land crabs, Lung of rodents Faeces of rodents Intermediate host
61
What is meant by trematodes What is their characteristic How do we classify them What are the 4 divisions
Flukes. Leaf-shaped worms All require freshwater snail as intermediate host By the organ of involvement Liver flukes, intestinal fluke, lung fluke, blood fluke
62
What is most common endoparasite in Hong Kong What type of fluke is it What cancer is it related to What are the life stages
Clonorchis (Opisthrochis) sinensis Liver fluke cholangiocarcinoma (bile duct cancer) 1. Ingested by Snails in the form of egg 2. Grow into miracidia--> sporocyst --> Redia -->cercaria 3. Cercaria penetrate under the scale of fish and become metacercaria 4. It forms excyst in duodenum and goes to bile duct to f=become adult 5. Lay embryonated egg that is found in faeces
63
What trematode is related with pneumonia What are the life stages of the parasite What is it's route in human body
Paragonimus spp. In snail: embryonated egg--> Miracidium -->Sporocyst --> Redia --> Cercaria -->metacercaria -->Excyst in stomach Stomach --> Intestinal wall --> Abdominal cavity --> Penetrates diaphragm -->Pleural cavity
64

MBBS IASM (24 decks)

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