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Microbiology Final > FINAL > Flashcards

FINAL Flashcards

1
Q

protozoa

A
  • single celled, animal-like
  • amoeba, ciliates, flagellates, sporozoans
  • structures: cytoplasmic membrane, cytoplasm, usually with flagellum
  • aquatic, obligate parasites
  • chronic or acute diseases: amerbiasis, sleeping sickness, chagas disease, STD
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2
Q

entamoeba histolytica

A
  • cause of amoebiasis (intestinal disease)
  • mostly mild diarrhea; dysentery, abdominal pain, fever fatigue, weight loss
  • ## tissue damage and in severe cases can lead to extra-intestinal infections
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3
Q

treatment of amoebiasis

A
  • drugs that target parasites both in the feces and the tissues
  • iodoquinol, metronizadole, dehydroemetine, chloroquine
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4
Q

naegleria fowleri

A
  • common, free living protozoans, accidental parasites
  • live in lakes, hot springs, swimming pools, hot tubs, moist soil
  • cause of primary amoebic meningoencephalitis (brain infection)
  • invades nasal mucosa
  • has cyst and trophozoite stages and can grow into flagellates as well
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5
Q

acanthamoeba

A
  • common, free living protozoans, accidental parasites
  • live in lakes, hot springs, swimming pools, hot tubs, moist soil
  • cause of granulomatous amoeba encephalitis (brain infection)
  • invades through broken skin, conjunctiva, lung, and eyes
  • course of infection lengthier than naegleria
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6
Q

treatment for naegleria meningoencephalitis

A
  • advances too fast to have an effective treatment

- amphotericin B, sulfadiazine, tetracycline, and ampicillin can be of some benefit if treated early in the infection

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7
Q

ciliates characteristics

A
  • has cilia for movement
  • two nuclei: macro and micro
  • undergo sexual and asexual production
  • life cycle includes trophozoites and mature cysts
  • natural habitats: large intestines of pigs and other domestic animals, primates: cysts in feces
  • causes balantidiosis
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8
Q

balantidium coli

A
  • infection of intestinal mucosa (ciliate protozoa)
  • symptoms: irritation, injury, nausea, vomiting, diarrhea, dysentery, and abdominal colic
  • healthy individuals are resistant
  • prevention: prevent food or drink contamination with pig manure
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9
Q

treatment of balantdium coli

A

oral tetracycline

- if this fails, dodoquinol, nitrimidazine or metronidazole

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10
Q

flagellates

A
  • mastigophorans
  • common feature: long, filamentous flagella
  • diseases:
    • trichomononiasis and giardiasis (mild)
    • trypanosomiasis and leishmaniasis (debilitating)
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11
Q

trichomonads

A
  • small, pear-shaped protozoa, with four flagella and an undulating membrane (flagellate)
  • does not produce cysts
  • reservoir: human urogenital tract: 50% asymptomatic
  • mode of transmission: sexual contact, communal bath, public facilities, mother to child
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12
Q

trichonomoniasis

A
  • 2nd most prevalent STD
  • symptoms:
    • females: foul smell, green to yellow vaginal discharge, vulvitis, cervicitis, urinary frequency and pain
    • males: urethritis, milky discharge, prostate infection
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13
Q

treatment of trichomoniasis

A

oral and vaginal metronidazole; both sexual partners have to be treated

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14
Q

Giardia lamblia

A
  • flagellate protozoa
  • causes giardiasis
  • most common flagellate isolated in clinical specimens
  • prominent cause of diarrhea
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15
Q

giardiasis

A
  • infection caused by giardia lamblia - prominent cause of diarrhea
  • outbreaks: traveler’s diarrhea, hikers, campers drinking from fresh mountain streams, children in day care centers
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16
Q

treatment of giardiasis

A

quinacrine or metronidazole

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17
Q

hemoflagellates

A
  • vector-borne blood parasites (in blood and tissues)
  • two major species:
    • trypanosoma
    • leishmania
  • life-threatening diseases
  • spread by blood-sucking insects
  • complicated life cycles
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18
Q

amastigote

A

round cells lacking a free flagellum

- development stage of hemoflagellates

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19
Q

promastigote

A

cell with single, free, anterior flagellum

- development stage of hemoflagellate

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20
Q

epimastigote

A
  • flagellate stage, with both flagellum and an undulating membrane
  • development stage of hemoflagellates
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21
Q

trypomastigote

A

the large, fully formed stage of trypanosoma

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22
Q

leishmania development stages

A
  • amastigote - intracellular in human macrophages

- promastigote - found in sand fly gut; infective to humans

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23
Q

trypanosoma brucei development stages

A
  • epimastigote - present in salivary glands of tsetse fly

- trypomastigote - in biting mouthparts of tstete fly; infective to humans

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24
Q

trypanosoma cruzi development stages

A
  • ALL STAGES OCCUR
  • amastigote: intracellular in human macrophages, liver, heart, spleen
  • promastigote: occurs
  • epimastigote: present in gut of reduviid
  • trypomastigote: in feces of reduvid big; transferred to humans
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25
Q

trypanosoma brucei

A
  • one of the two major trypanosoma species
  • cause of african sleeping sickness
  • two subspecies: T.b. gambiense (west africa) T.b. rhodesiense (east africa)
  • principle vector: tsetse flies
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26
Q

trypanosoma cruzi

A
  • cause of chagas disease

- insect host: kissing bug

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27
Q

sleeping sickness

A
  • caused by trypanoma brucei
  • intermittent fever, enlarged spleen, swollen lymph nodes, joint pain
  • personality change, sleep disturbances (sleepiness in the day and sleeplessness at night)
  • advanced neuromuscular disorders:
    • muscular tremors, shuffling gait, slurred speech, epileptic seizures, paralysis
    • death: coma, secondary infections, heart damage
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28
Q

treatment of sleeping sickness

A
  • chemotherapy: successful if administered prior to brain damage
  • treatment of brain infections: expensive
    • melarsoprol - toxic arsenic-based drug
    • difluoromethylornithine (DFMO): less toxic
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29
Q

why can’t the immune system defeat the trypanosome?

A
  • trypanosomes produce a large number of surface antigen in succession (>100 antigenic variations)
  • antibodies produced by the host fail to stop bugs with new antigen
  • host becomes overwhelmed
  • difficult to immunize
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30
Q

chagas disease

A
  • fever, swelling lymph nodes, spleen and liver
  • favored targets are heart muscle and large intestine
  • heart enlargemnt and death in 2 years
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31
Q

treatment of chagas disease

A
  • nifurtimox and benzonidazole for early treatment

- side-effects are damaging (humans cells similar to protozoans - cross-reactivity)

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32
Q

leishmaniasis

A
  • capillary infection of leishmania (gets into capillaries and causes tissue damage)
  • transmitted among mammals by phlebotomine flies (sand flies)
  • endemic to equatorial regions
  • special risks: travelers and immigrants
  • death by destruction of tissues
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33
Q

apicomplexan parasites

A
  • sporozoan protozoas
  • lack locomotor organelles in the mature stage
  • sexual and asexual reproduction
  • most important human pathogens
    • plasmodium - malaria
    • toxoplasma - toxoplasmosis
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34
Q

malaria

A
  • caused by plasmodium (apicomplexan parasite)
  • symptoms:
    • chills and fever at regular intervals, followed by sweating, due to synchronous rupturing of RBCs
    • anemia in young children; organ rupture from accumulated cell debris (spleen, liver and kidneys)
    • long recovery: up to 5 years
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35
Q

plasmodium

A
  • cause of malaria
  • obligate intracellular sporozoan
  • four species: P. malariae; p. vivax, P. falciparum, P. ovale
  • transmission
    • mostly by female anopheles mosquitoes
    • occasionally sharing needles
    • blood transfusions
    • mother to child
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36
Q

P. falciparum

A
  • causes the most severe cases of malaria

- persistent fever, rapid pulse, cough, weakness for weeks without relief, high death rate in acute phase

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37
Q

diagnosis of malaria

A
  • stained blood smear
  • antibodies
  • DNA-PCR analysis
38
Q

treatment of malaria

A
  • chloroquine, less toxic side effects for non-resistant strains
  • for resistant strains - mefloquine or quinine
  • for eliminating the parasites from the liver: use primaquine or proguenil
39
Q

toxoplasma gondii

A
  • cause of toxoplasmosis

- exposure rate: 90%

40
Q

toxoplasmosis

A
  • caused by toxoplasma gondii
  • most cases: mild, sore throat, lymph node enlargement, low grade fever
  • immunodeficient patients: brain lesions, fetal disruption of the the heart and lungs
  • infection in pregnant women (33% chance transmission to fetus) -> leads to still birth, liver failure, hydrocephalus, convulsions, and retina damage and blindness
41
Q

Helminth Life Cycle A

A
  • route of infection: oral
  • source: water and food contaminated with mature eggs
  • larvae hatches in tissues and then migrates into the intestine to mature and mate
  • embryonic eggs are then released back into the environment
42
Q

Helminth Life Cycle B

A
  • route of entry: skin penetration
  • source: contaminated soil
  • eggs develop into the larvae to allow skin penetration in the environment
  • larvae migrates into the intestine to mature and mate
  • embryonic eggs are then released back into the environment
43
Q

Helminth Life Cycle C

A
  • route of entry: oral
  • source: contaminated meat with encystment in the muscle
  • larvae migrate into the intestines to mature and mate
  • embryonic eggs are then released back into the environment to be taken up by livestock again
44
Q

Helminth Life Cycle D

A
  • two routes of infection: direct skin penetration or contaminated meat
  • larvae migrate to intestine or bladder to mature or mate
  • embryonic eggs are then released back into the environment
  • eggs develop into the first larval stage then infect intermediate host then, enter larval stage
  • second larval stage can be taken in through skin penetration of contaminated meat
45
Q

Helminth Cycle E

A
  • parasite transferred through insect bites
  • infective larvae get lodged in tissues and new larvae are released into circulation and ready to be transferred into new insects and hosts
46
Q

pathology of helminth infection

A
  • symptoms: enlargement of organs, hemorrhage, weight loss, anemia
  • ## worms migrate with enzymes to liquefy and penetrate tissues -> tissue damage, blocked ducts and organs, toxic secretions, pressure
47
Q

methods for diagnosis of helminths

A
  • eosinophilia (increase in eosinophils)
  • travel history
  • detection of eggs in stools, urine or blood
48
Q

Ascaris Lumbricoides

A
  • intestinal nematodes
  • cycle A
  • causes ascariasis
  • retain motility (do not attach)
  • severe inflammatory reactions mark the migratory route
  • allergic reactions can occur
  • heavy worm loads can retard physical and mental development
49
Q

Hookworms

A
  • intestinal nematode
  • cycle B
  • larbae burrow into the skin -> circulation -> lungs –> throat –> small intestine
  • symptoms:
    • dermatitis
    • pneumonia
    • nausea, vomiting, pain, bloody diarrhea
    • chronic fatigue, anemia
50
Q

Strongyloidiasis

A
  • intestinal nematode
  • cycle B
  • threadworm (also called pinworm) infections
  • 100 to 200 million patients worldwide
  • symptoms:
    • bloody diarrhea
    • liver enlargement
    • bowel obstruction
    • malabsorption
51
Q

trichinella spiralis

A
  • intestinal nematode
  • cycle C
  • mammalian hosts
  • encysted larval form in muscles
  • humans infections from raw meat from swine or bear
52
Q

trichinosis

A
  • caused by trichinella spiralis
  • symptoms:
    • initially: fever, diarrhea, nausea, abdominal pains, and sweating.
    • Second phase: intense muscle and joint pain, shortness of breath, and eosinophilias –> heart and brain damage –> death
  • prevention: cook meat well. freezing also kills the worm larvae
53
Q

filarial nematodes

A
  • tissue nematode
  • cycle E
  • long, threadlike worms
  • biphasic life cycle: alternating between humans and mosquitoes or flies
  • two major species: wuchereria bancrofti and oncocerca volvulus
54
Q

bancroftian filariasis

A
  • wuchereria bancrofti
  • affects 120 million people
  • symptoms: elephantiasis
    • inflammation and blockage of main lymphatic channels –> accumulation of fluid
55
Q

onchocerca volvulus

A
  • tissue nematode
  • causes river blindness/ onchocerciasis
    • inflammation, and granulomatous lesions
    • river blindness: invasion of eyes
  • transmitted by black flies that breed along rivers in west Africa
56
Q

Loa Loa

A
  • tissue nematode
  • cycle E
  • the African eye worm
  • transmitted by a fly
  • treatment: pull worm out; diethylcarbamazine
57
Q

Dracunculus medinensis

A
  • tissue nematode
  • cycle D
  • dragon worm
  • found in india, middle east, and central Africa
  • parasite first infects cyclops (arthropod found in still water
  • infection cycle: ingestion of larva in cyclops -> intestine -> subcutaneous tissue -> irritants -> itching blisters (fireworm) -> eruption in water -> cyclops
58
Q

blood flukes/ schistosomes

A
  • trematode
  • cycle D
  • causes schistosomiasis
  • life cycle: infected humans -> eggs -> ciliated larva (mircadium) -> snails (host) -> forked larva (cercaria) -> human skin -> circulation -> liver -> intestine -> feces
59
Q

schistosomiasis

A
  • caused by schistosomes/ blood flukes
  • symptoms: fevers, chills, diarrhea, and cough
    • chronic infections: hepatomegaly, splenomegaly, bladder obstruction, kidney damage, blood in urine, brain damage
  • control: snail-eating fish
60
Q

cercaria

A

capable of penetrating exposed human skin

61
Q

liver and lung flukes

A
  • trematode/fluke
  • cycle D
  • develop in liver or lung
  • sexual development in humans
  • intermediate hosts: snails
  • infection by ingesting inadequately cooked or raw freshwater fish and crustaceans
  • larvae hatch and crawl into the bile duct -> matures -> shed eggs into the intestinal tract -> feces into standing water -> snails -
62
Q

Cestode/ Tapeworm

A
  • cycle C
  • morphology:
    • scolex: head - sucker, no mouth
    • neck
    • strobila: ribbon composed of reproductive segments (proglottids)
63
Q

taenia saginata

A
  • beef tapeworm
  • cause of taeniasis
  • 2000 proglottids anchored by a scolex with suckers
  • worldwide
  • cows infected by ingesting in fields with proglottids or eggs contamination
  • humans infected by eating raw beef
  • symptoms: mild abdominal pain and nausea
64
Q

taenia solium

A
  • swine tapeworm
  • T. solium is smaller than T. saginata
  • endemic in areas consumin raw or partially cooked pork
65
Q

cysticercosis

A

a severe form of Taenia solium infection

  • tapeworm larvae migrate to different tissues
  • form peculiar cysticerci
  • tissue damage - heart, eye, brain
66
Q

anisakis

A
  • fish helminths
  • cause of anisakiasis
    • tingling sensation in the throat a few hours after eating sushi or sashimi
    • anisakis larvae will try to burrow into the tissue causing irritation and vomiting but usually gets expelled without further symptoms
    • can cause acute GI pain, cramping and vomiting
67
Q

diphyllobothrium latum

A
  • tapeworm/cestode
  • found in the great lakes region, Canada, and Alaska
  • humans are definitive hosts
68
Q

control of helminth infections

A
  • sewage treatment
  • now use of human feces as fertilizer
  • water treatment
  • no raw meat
  • chemotherapy: paralyze worms and interfere with worm metabolism
69
Q

Ivanovski and Beijernick

A

identified tobacco mosaic virus causing a tobacco disease (1890)

70
Q

Louis Pasteur

A
  • postulated that rabies was caused by “living things” smaller than bacteria
  • in 1884, developed the first vaccine for rabies
  • proposed the term virus
71
Q

Loeffler and Frosch

A

identified foot-and-mouth virus

72
Q

size of viruses

A
  • animal viruses 20 nm to 450 nm

- electron microscope needed to observe viruses (up to 5,000,000x magnification)

73
Q

negative staining

A

use thin layers of an opaque salt to outline the shape of the virus against a dark background and to enhance the texture of the viral surface

74
Q

positive staining

A

detects internal details of proteins and nucleic acids

75
Q

shadowcasting

A

spread metallic vapor from a certain angle. the metallic coating over the surface approximates the viral contours and a shadow is cast on the unexposed side

76
Q

capsid

A

a protein shell that surround the nucleic acid in the central core
- made up of identical subunits called capsomers

77
Q

nucleocapsid

A

capsid + nucleic acid

78
Q

envelope

A

some possess modified host cell membrane that wraps outside of the nucleocapsid

79
Q

Icosahedron

A
  • 3D, 20 sided object, with 12 evenly spaced corners
  • constructed from single or multiple types of capsomers
  • variations in the number of capsomer in each virus
  • with or without envelop
80
Q

papillomaviruses

A

icosahedral virus with no envelope

81
Q

herpes virus

A

enveloped icosahedron

82
Q

functions of viral capsid/ envelope

A

protection of nucleic acids:

  • capsids of enteric (intestinal) viruses such as polio and hepatitis A are resistant to the acid and protein- digesting enzymes of the GI tract
  • host cell invasion (adsorption; introduction of viral DNA or RNA)
  • contain antigenic elements for immune responses
83
Q

poxviruses

A
  • complex virus
  • very large
  • DNA
  • lack regular capsid, but have several layers of lipoproteins, and coarse surface fibrils
  • cause smallpox
84
Q

bacteriophage

A
  • complex virus
  • DNA
  • polyhedral head
  • helical tail
  • fibers for attachment to the host cells
85
Q

Mumps

A
  • enveloped virus
  • helical nucleocapsid
  • RNA
86
Q

Herpes virus

A
  • enveloped virus

- DNA

87
Q

rhabdovirus

A
  • enveloped virus

- RNA

88
Q

HIV

A
  • enveloped viruses

- RNA

89
Q

adenovirus

A
  • Naked viruses

- DNA

90
Q

multiplication cycle in bacteriophages

A
  • (adsorption: tail fibers bind to specific bacterial surface receptors
  • injection of phage DNA into the bacteria by pushing the inner tube through the bacteria wall into the bacteria
  • phage DNA: direct synthesis of phage parts: capsid heads, parts of the tail, new genome, and enzyme that weakens the cell wall in preparation of phage release
  • spontaneous assembly to generate progeny phages
91
Q

penetration of animal viruses

A
  • via endocytosis: entry into cells in a vacuole or vesicle
    • enzymes in the vesicle digest away the envelope and capsid: uncoating to release viral nucleic acid into the cytoplasm (ex: herpes virus)
  • membrane fusion between viral envelope and the cytoplasmic membrane, releasing nucleic acid into the cytoplasm (ex: mumps)
92
Q

plaques

A

develop when the viruses released by an infected cell radiate out to adjacent cells

  • as new cells become infected and they die and release more viruses and result in more cell lysis
  • lysed cells give rise to a clear area

Microbiology Final (1 decks)

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