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Eukaryotic Microbes Flashcards

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Biology 101 flashcards
1
Q

Protozoa Eukartyotic Diseases

A

Entamoeba, Leishmania, Malaria, Trichomonas

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2
Q

Fungi Eukaryotic Diseases

A

Candida albicans, Histoplasma

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3
Q

Do Fungi and Protozoa have cell walls?

A

Fungi and algae do, protozoa don’t.

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4
Q

Name some characteristics of Protozoa.

A 
Unicellular
No cell wall
Colourless
Motile
No chlorophyll (unlike algae)
No fruiting bodies (unlike slime moulds)
Phagocytotic
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5
Q

Name the four groups of Protozoa.

A

Sarcodina, Mastigophora, Ciliophora, Apicomplexans

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6
Q

Name a disease and the characterising feature of Sarcodina.

A

Entamoeba histolytica causes amoebic dysentry because Sarcodinas have ameoeboid motion.

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7
Q

Name a disease and the characterising feature of Mastigophora.

A

Trypanosomes cause leishmaniasis, African sleeping sickness and Chagas dieases, helped by the flagella which is charateristic of Mastigophora.

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8
Q

Name a disease and the characterising feature of Ciliophora.

A

Balantidium coli has cilia which helps to cause intestinal dysentry.

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9
Q

Name a disease and the characterising feature of Apicomplexans.

A

Malaria and Toxoplasma gondii are caused by non-motile protozoa apicomplexans.

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10
Q

Entamoeba histolytica main points

A

Can cause asymptomatic infections
Can cause symptomatic or extra-intestinal amoebiasis
Intestinal amoebiasis causes dysentry, gastroenteritis and post-amoebic colitis
Extra-intestinal causes liver enlargement and abscesses
Causes 50,000 - 100,000 deaths annually worldwide

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11
Q

Entamoeba histolytica infection and life cycle

A

Initial infection by ingestion of mature cysts by faecally contaminated food or water
Excystation in small intestine
Trophozoites released and migrate to large intestine
Trophozoites multiply by binary fission and produce cysts
Trophozoites cannot exist outside body, will be killed in GI tract if ingested

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12
Q

Entamoeba histolytica morphology

A

Trophozoites 10 - 60 microns
Motile
Anaerobic (no mitochondria)
Endoplasm contains nuclues and food vacuoles
Cysts much small with thin transparent wall and 4 nuclei

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13
Q

Treatment and prevention of entamoeba histolytica

A

Good personal hygiene
Metronidazole (for anaerobic organisms) treats intestinal disease and liver abscesses
Trophozoite removal by combination of iodoquinol, dioxanide furoate and antibiotics

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14
Q

Name the two types of Leishmaniasis

A

Cutaneous and Visceral (external and internal)

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15
Q

Leishmania transmission

A

Sandfly, hosted by dogs, rodents and humans

Can be zoonotic or anthroponotic

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16
Q

Leishmania lifecycle

A

Sandfly takes blood meal and injects promastigote stage
Promastigotes phagocytised by macrophages
Promastigotes transform into amastigotes in macrophage
Amastigotes multiple in tissue cells
Sandfly takes blood meal, ingests macrophages with amastigotes
Ingestion of parasitised cell
Amastigotes transform to promastigotes in midgut
Divide in midgut and migrate to proboscis
Sandfly takes blood meal and injects promastigotes

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17
Q

Trichomaniasis main points

A 
Affects more than 250m people
Human to human by sexual intercourse
No cyst, transmission occurs by trophozoite
Hydrogenosomes instead of mitochondria
Anaerobic
Wobbling and rotating course of motility
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18
Q

Trichomonas vaginalis

A

4 anterior flagella
1 posterior flagella
Median rod called axostyle
1 nucleus

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19
Q

Hydrogenosome process

A

Glucose goes through glycolysis to produce pyruvate
Pyruvate releases CO2 and H2 to produce Acetyl-CoA
Acetyl-CoA and ADP produce ATP and acetate

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20
Q

Key enzymes of the hydrogenosome

A

pyruvate:ferrodoxin oxidoreductase

hydrogenase

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21
Q

Treatment of trichomaniasis

A

Metronidazole, activated in hydrogenosome by electrons of pyruvate:ferrodoxin oxidoreductase transferred to metronidazole via ferrodoxin, reducing drug to cytotoxic form

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22
Q

What are fungal cell walls comprised of?

A

Glucan and chitin

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23
Q

What are the three fungal groups?

A

Moulds, mushrooms and yeasts

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24
Q

How do fungi cause disease?

A

Hypersensitivity, mycotoxins or mycosis

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25
Q

How do fungi feed?

A

By exoenzymes secreted before ingestion - heterotrophic

This can cause tissue damage in a host

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26
Q

Name the three types of mycoses.

A

Superficial, subcutaneous and systemic.

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27
Q

Explain and give examples of superficial mycoses.

A

Common, mostly benign, self limiting. Only infect surface areas such as skin, hair and nails. Ringworm caused by microsporum and athletes foot caused by trichophyton.

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28
Q

Explain and give examples of subcutaneous mycoses.

A

Colonisation of deeper skin layers, starting from fungal infection of a small wound. Sporotrichosis caused by sporothrix.

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29
Q

Explain and give examples of systemic mycoses.

A

Primary or secondary infections. Cryptococcosis caused by Cryptococcus neoformans.

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30
Q

What is histoplasmosis?

A

A primary systemic mycosis which induces a granulomatous reaction in tissues.

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31
Q

What is histoplasma capsulatum?

A

The fungus that causes histoplasmosis. It is dimorphic, at room temperature takes on mycelial form becoming macro/microconidia. At body temperature it morphs into a yeast.

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32
Q

How is histoplasmosis contracted and diagnosed?

A

Infection by conidia inhalation, diagnosis by x-ray and histoplasmin skin test.

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33
Q

What is candida albicans?

A

The fungus that causes thrush. Part of normal microflora in upper respiratory, GI and vaginal tract but suppressed by other commensal bacteria. Damage to this bacteria causes thrush.

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34
Q

Name two eukaryotic microbial diseases found in New Zealand.

A

Giardiasis caused by Giardia lamblia (flagella) causes gastrointestinal disease.
Cryptosporidiosis caused by Cryptosporidium parvum (protozoa) causes vomiting and diarrhoea.

35
Q

How do apicomplexans obtain nutrients?

A

By taking them up in the soluble form across the cytoplasmic membrane.

36
Q

What can apicomplexans form to transmit disease?

A

Sporozoites.

37
Q

What are apicoplasts?

A

Part of an apicomplexan that carry out biosynthetic reactions and are derived from red algal cells by endosymbiosis.

38
Q

What is a sporozoan?

A

A microbe that ccannot form true resting spores but can form sporozoites.

39
Q

Name the main points of toxoplasmosis.

A

Sporozoal disease
Caused by Toxoplasma gondii, an obligatory intracellular parasite
Affects 50% of population, normally asymptomatic
Mainly in immunocompromised people
Infection by undercooked meat or cats
Can involve many tissues e.g. muscle, lymph nodes etc.

40
Q

Describe the life cycle of toxoplasmosis.

A

Immature oocyte passes with feces to soil
Oocyst - Sporogony - Mature oocyst and sporocyst with 4 sporozoites
Mature oocyte ingested by non-feline animals (or directly by cat)
Sporozoite invade tissue of non-feline animal and produce tachyzoites and bradyzoites
Human or mouse eat zoitocysts (with bradyzoites)
Cat eats mouse infected with oocyst or zoitocyst
Bradyzoites released in feline intestine
Bradyzoite infects cell - merozoite - macrogamete - microgamete - immature oocyte

41
Q

Name the main points of malaria.

A

Caused by Plasmodium species which infect and destroy red blood cells
Paroxysm (fever and chill)
Symptoms include fever, headache, vomiting
Death by anaemia, clogged capillaries, cerebral malaria, pulmonary odoema, kidney failure

42
Q

Malaria epidemiology

A

300m-500m clinical cases a year
2m deaths a year
NZ gets 70 imported cases a year
Spread by bite of infected female mosquito

43
Q

Name the 4 plasmodium species that can cause malaria

A

Vivax, ovale, falciparum, malariae

44
Q

Describe the malaria life cycle.

A

Infection by mosquito bite
Sporozoites in blood
Invade liver, transform to merozoites
Merozoites exit liver, go through asexual reproduction
Gametocytes form which are transmitted to mosquito
Mosquito forms sporozoites from gametocytes

45
Q

What are the stages of malaria within a human host?

A

Sporozoites
Exoerythrocytic schizogonic phase in liver
Hepatocytes in parasitophorous vacuole
Sporozoite - schizont
Trophozoite - merozoite
Merozoites burst from hepatocyte to blood stream
Erythrocytic schizogonic phase
Merozoites endocytised by erythrocyte
Early trophozoite stage/Signet ring stage
Mature trophozoites - schizonts - new merozoites
Merozoites repeat or undergo gametogenesis

46
Q

What are the stages of malaria within a mosquito host?

A 
Gamogony
Sporogony
Gametes taken up by feeding
MIcro/macrogamete fuse - diploid zygote
Ookinete - oocyst - sporoblast
Sporozoites
47
Q

What is schizogony?

A

MItotic division in which several divisions of the nucleus occur before cytoplasm division/

48
Q

Name three evolutionary mechanisms that control malaria.

A

Sickle cell anaemia heterozygosity for falciparum.
Duffy antigen null for vivax.
Thalassaemia: globin chain production imbalances produce reactive oxygen species which injure and kill malaria parasites.

49
Q

Name three types of malarial control.

A

Antimalarial drugs, vector control, avoiding mosquito bites.

50
Q

What is another name for trypanosomiasis?

A

African Sleeping Sickness

51
Q

What are some first stage symptoms of trypanosomiasis?

A 
Chancre at site of insect bite
Swollen cervial lymph nodes
Winterbottoms sign
Headaches
Fever
Joint pain
Itching
Weakness
52
Q

What is Winterbottoms sign?

A

The enlargement of lymph nodes in the neck.

53
Q

What are some second stage symptoms of trypanosomiasis?

A 
Inability to concentrate
Mood swings
Indiferrence
Lethargy
Aggressiveness
Disrupted sleeping patterns
Weight loss
Seizures
Coma
Death if untreated
54
Q

What causes trypanosomiasis?

A

Trypanosoma brucei

55
Q

Name the 3 subspecies of Trypanosoma brucei and their reservoirs.

A

Trypanosoma brucei rhodisiense: cattle reservoir, infects humans and animals
Trypanosoma brucei gambiense: Only infects humans
Trypanosoma brucei brucei: Only infects cattle

56
Q

How are the 3 subspecies of Trypanosoma brucei distinguished from one another?

A

Although morphologically the same, they are all transmitted by different types of Glossina fly.

57
Q

What is another name for the Glossina species?

A

The Tsetse fly

58
Q

How does transmission of trypanosomiasis occur?

A

Via the Tsetse fly when it takes a blood meal or rarely from person to person by blood transfusion and sexual contact.

59
Q

What are trypanosomes?

A

Blood feeding hemoflagellates with a kinetoplast.

60
Q

What is a kinetoplast?

A

A mass of circular DNA present in a single large mitochondrion. They are only found in the kinetoplastida class of protozoa.

61
Q

Describe the Trypanosome life cycle.

A 
Trypomastigote divides
Trypomastigotes in blood stream
Tsetse takes blood meal
Epimastigote in fly gut
Metacyclic trypomastigote in salivary gland of fly
Tsetse blood meal from reservoir host
62
Q

Control of trypanosomiasis

A

Reducing disease reservoir

Vector control

63
Q

How is trypanosomiasis diagnosed?

A

By a Car Agglutination Trypanosomiasis Test, microscope and lumbar puncture (for stage 2)

64
Q

Preventative measures for trypanosomiasis

A

Neutral clothing
Thicker clothing
Check vehicles for Tsetse
Avoid brushes during the day (they are diurnal)

65
Q

Name the four main drugs for Trypanosomiasis.

A

Suramin, Pentamidine, Melarsoprol, Eflornithine

66
Q

Name six main drugs for Malaria.

A

Quinine, Artemisinin, Atovaquone, Doxycycline, Chloroquine, Melfloquine

67
Q

How does quinine protect against malaria?

A

Quinine inhibits hemozoin biocrystalisation which allows cytotoxic heme to be produced, which kills malarial parasites.

68
Q

How does Artemisinin protect against malaria?

A

Theoretically, the heme reduces the peroxide which causes a cascade and oxygen free radicals, killing the parasites.

69
Q

How does Atovaquone protect against malaria?

A

Atovaquone inhibits dihydrofolate reductase which converts folic acid to folinic acid in the parasite, essential for reproduction.

70
Q

How does Doxycycline protect against malaria?

A

Usually used as part of combination therapy due to it’s delay because it inhibits growth of the apicoplasts so biosynthetic reactions can’t progress.

71
Q

How does Chloroquine protect against malaria?

A

Interferes with haemozoin formation and forms free-haem-chloroquine complex, toxic to parasite.

72
Q

How does Melfloquine protect against malaria?

A

Unknown, thought to act as blood schizonticide by inhibiting heme polymerase.

73
Q

How does Suramin protect against trypanosomiasis?

A

Used for 1st stage T. b. rhodesiense by inhibiting heterotrimeric G protein coupled receptors, causing lack of GTP and energy, therefore parasite dies.

74
Q

How does Pentamidine protect against trypanosomiasis?

A

Used for first stage T. b. gambiense by intravenous infusion or intramuscular injection, theoretically blocks synthesis of DNA, RNA, proteins and phospholipids.

75
Q

How does Melarsoprol protect against trypanosomiasis?

A

Used for second stage T. b. rhodesiense/gambiense by intravenous injection, by invasion of the trypanosome and inhibiting pyruvate kinase. ATP is inhibited, the parasite has no energy and dies. Organoarsenic, very dangerous, can elicit encephalopathic reactions.

76
Q

How does Eflornithine protect against trypanosomiasis?

A

Used for second stage T. b. gambiense, safer than melarsoprol but requires 4 injections a day for 2 weeks. Works by suicide inhibiting, irreversibly binding to ODC and preventing orthinine from binding ODC. Trypanosomes cannot work without ODC so they die.

77
Q

What is another name for American Trypanosomiasis?

A

Chagas Disease

78
Q

What is Chagas disease caused by?

A

Trypanosoma cruzi

79
Q

What is the vector for Chagas?

A

The ‘kissing bug’ which deposits feces while taking a blood meal which will later be rubbed into the bite wound.

80
Q

What are the main differences between African and American Trypanosomiasis?

A

T. cruzi can survive intracellularly
T. cruzi does not make variable surface antigens
Chagas is spread by the kissing bug, so named because it bites peoples faces when they are asleep
Chagas spread by T. cruzi, Sleeping Sickness spread by T. brucei
Sleeping sickness spread by injection of saliva, Chagas spread by rubbing fecal matter into bite wound

81
Q

What is a chagoma?

A

The swelling of the initial site of infection after being bitten by T. cruzi.

82
Q

What is the acute phase of Chagas disease?

A

The initial stage of infection, lasts about 2 months after bite. Parasites circulate in blood, asymptomatic or flu resembling symptoms.
Skin lesions or styes.

83
Q

What is the chronic phase of Chagas disease?

A

Parasites in heart and digestive muscle.
30% = cardiac disorder
10% = digestive, neurological, mixed disorders
Sudden death or heart failure

84
Q

Why is chemotherapy not very effective in treating Chagas?

A

Because the parasite resides in host cells which are impermeable to drugs. Vector control preferred.

Microbiology (6 decks)

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