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Microbiology > 5.51 > Flashcards

5.51 Flashcards

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1
Q

Protozoa

• Diverse group of

A

eukaryotic microbes

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2
Q

Protozoa

• Related only by their

A

simple organization: unicellular or

multicellular without specialized tissues

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3
Q

Protozoa
• Most are
• Some are

A

free-living in aquatic environments or on decaying organic matter
parasitic

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4
Q

Encystation (many protozoa are capable of this)

A

• formation of a cyst

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5
Q

• formation of a cyst

– (2)

A

resting state with a wall and low metabolic

activity

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6
Q

function of cysts (3)

A
  • protection from changes in environment
  • sites for nuclear reorganization and cell division
  • transfer from one host to another
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7
Q

Excystation

A

• escape of vegetative form from cyst

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8
Q

Excystation

• usually triggered by

A

return to favorable

environment

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9
Q

Excystation

trophozoite (2)

A

– vegetative form released by parasitic species
– excystation often triggered by entry into new
host

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10
Q

some protozoa are —

A

nonmotile

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11
Q

• motile species use one

of following: (3)

A 
– cilia
– flagella
– pseudopodia (s.,
pseudopodium)
• cytoplasmic extensions
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12
Q

Zooflagellates

Motile due to

A

one or

more flagella

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13
Q

Giardia lamblia

giardiasis -

A

gastrointestinal disorder

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14
Q

Trichomonas vaginalis

trichomoniasis -

A

sexually

transmitted disease

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15
Q

Trypanosomes

3

A

hemoflagellates
important blood pathogens
e.g., African sleeping sickness

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16
Q

Giardiasis
— disorder
Most common cause of

A

gastrointestinal

epidemic waterborne diarrheal disease

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17
Q

Giardiasis

caused by

A

Giardia lamblia
– forms cysts and trophozoites
– trophozoites attach to intestinal epithelium and interfere with nutrient absorption

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18
Q

Giardiasis

transmission usually by (3)

A

cyst-contaminated water
– numerous animal reservoirs
– asymptomatic human carriers are common

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19
Q

Giardiasis
• clinical manifestations
– acute giardiasis - (5)
– chronic gastritis -(2)

A

severe diarrhea, epigastric pain, cramps, voluminous flatulence,
and anorexia

intermittent diarrhea with periodic appearance and remission of
symptoms

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20
Q

Giardiasis

• treatment, prevention, and control (2)

A

– antiprotozoal agents (metronidazole)
– avoiding contaminated water or purify it by boiling or filtering (cysts are resistant
to chlorine treatment)

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21
Q 
Trichomonas vaginalis
sexually transmitted (2)
A

– One of the most common sexually transmitted
diseases (found in 15% of women)
– No cyst stage (only trophozoites)

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22
Q 
Trichomonas vaginalis
clinical manifestations (3)
A

– accumulation of leukocytes at site of infection
– in females, results in yellow purulent vaginal discharge and itching
– in males, usually asymptomatic or burning urination

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23
Q

Trichomonas vaginalis

treatment, prevention, and control (2)

A

– observation of parasite in vaginal discharge, semen or urine
– antiparasite therapy (metrodiazole)

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24
Q

Trichomonas tenax resides in —

Usually associated with —
Aspiration associated with —

A

mouth

poor oral hygiene
pneumonia

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25
Q

Hemoflagellate Diseases

• caused by

A

flagellated protozoa

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26
Q

Hemoflagellate Diseases

– two major groups (2)

A
  • leishmanias

* trypanosomes

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27
Q

Hemoflagellate Diseases

• transmitted by bites of

A

infected arthropods

• infect blood and tissues of humans

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28
Q

Trypanosomes
hemoflagellates
important — pathogens

A

blood

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29
Q

African trypanosomiasis
• African sleeping sickness
• transmitted by

A

tsetse flies

– reservoirs included domestic cattle and wild animals

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30
Q

African trypanosomiasis

• Chronic bloodstream infection with

A

bouts of parasitemia

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31
Q

African trypanosomiasis

• CNS invasion after

A

months to years

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32
Q

African trypanosomiasis

clinical manifestations

A

– interstitial inflammation and necrosis within lymph
nodes and small blood vessels of brain and heart,
leading to lethargy and death within 1 to 3 years

33
Q

African trypanosomiasis

• diagnosed by

A

observation of motile parasites in blood

34
Q

African trypanosomiasis

• drug therapy during systemic stage but not as effective when

A

CNS

involved. Vaccine not useful due to antigenic variation.

35
Q

tsetse fly

2

A

• Intermediate host
between animal reservoir &
humans
• Determines disease range

36
Q

Chagas disease
• American trypanosomiasis (Latin America; sporadic in southern USA)
• transmitted by

A

kissing bug (= reduviid bug)

– reservoirs included domestic cattle and other animals
– In endemic regions most people in population infected in childhood
– Early disease mild; small % develop complications 10-20 years later

37
Q

Chagas disease

heart disease and other disorders due to destruction of parasitized cells in the liver, spleen, lymph nodes, and central nervous system
(2)

A

– Megaesophagus, megacolon (due to damage to nerves in GI tract)
– Cardiomyopathy (due to damage to heart muscle)(sudden death from arrhythmia)

38
Q

Chagas disease

tx (2)

A

• no treatment available for late complications
Vaccines not useful because of
antigenic variation- genetic switching

39
Q

Chagas disease
Vector
(2)

A

• Parasite discharged in feces
• Enter human body through
bite wound

40
Q

Leishmaniasis

• caused by

A

Leishmania species (several, with different tissue tropisms)

41
Q

Leishmaniasis

transmitted by

A

sand flies when they take a blood meal (usually tropical)
– animal reservoirs include canines and rodents
– Leishmania survives and differentiates in macrophages (superoxide
dismutase)

42
Q

Leishmaniasis

three forms of infection

A

– mucocutaneous, cutaneous, and visceral

43
Q

visceral
•involves
•clinical manifestations (2)

A

tissue macrophage disfunction

–intermittent fever and enlargement of
spleen or liver
–recovery provides permanent immunity

44
Q

mucocutaneous

A

lesions of mouth, nose,
throat and skin that cause
extensive scarring and
disfigurement

45
Q

cutaneous (2)

A 
•papules that develop
into crustated ulcers
•healing occurs with
scarring and
permanent immunity
46
Q

Leishmaniasis

treatment, prevention, and control (2)

A 
Several types of drugs available
(including amphotericin B, the
polyene anti-fungal agent)
– vector and reservoir control, and
epidemiological surveillance
47
Q

Amoebiasis (amoeboid protozoa)
• amoebic —
• caused by

A

dysentery

Entamoeba histolytica

48
Q

Amoebiasis

• transmission by

A

ingestion of cysts

49
Q

Amoebiasis

clinical manifestations

A

– asymptomatic to fulminating dysentery,
exhaustive diarrhea, and abscesses of
liver, lungs, and brain

50
Q

Amoebiasis
treatment, prevention, and control
(3)

A 
– observation of trophozoites in fresh
warm stools or cysts in ordinary stools,
and serological tests
– Metronidazole therapy (amoebas carry
out anaerobic metabolism and drug
penetrates tissue well to destroy invasive
pathogens)
– avoiding contaminated water and food
and hyperchlorination or iodination of
water supplies to destroy waterborne
cysts
51
Q

Phylum Apicomplexa
• lack — organelles
• all have — complex

A

locomotor

apical

52
Q

Phylum Apicomplexa
lack locomotor organelles
– except for (2)

A

male gametes and

zygotes

53
Q

Phylum Apicomplexa
all have apical complex
– arrangement (3) at
one end of cell

A

fibrils, tubules,

vacuoles, and other organelles

54
Q

Apicomplexan life cycles

involves (2)

A

• involves two different hosts (usually mammal and
mosquito)
• involves both asexual and sexual phases

55
Q

Apicomplexan life cycles
– schizogony
(2)

A

• asexual phase
• rapid series of mitotic events producing
infective organisms

56
Q

Apicomplexan life cycles

– oocyst (3)

A

• produced during sexual phase
• thick-walled, diploid structure
• undergoes meiosis to produce haploid
spores

57
Q 
Important sporozoan genera
(sporozoan = apicomplexan)
• Plasmodium –
• Cryptosporidium –
• Toxoplasma –
A

malaria
cryptosporidiosis
toxoplasmosis

58
Q

Malaria

• caused by four species of

A

Plasmodium (Plasmodium falciparum is

most virulent; others are P. vivax, P. malariae, and P. ovale)

59
Q

Malaria

• transmitted by

A

bite of an infected female Anopheles mosquito

60
Q

Malaria

Reservoir:

A

humans

61
Q

Malaria

Intermediate host:

A

humans

asexual reproduction

62
Q

Malaria

Definitive host:

A

mosquito

sexual reproduction

63
Q 
Malaria
P. vivax and P. ovale form
--- (dormant forms)
within liver cells. These cause
--- (months to
years after initial disease).
A

hypnozoites

recurrent malaria

64
Q

Malaria

clinical manifestations

A 
periodic attacks of chills and
fever (coincides with RBC lysis
and merozoite release, which
stimulates cytokine
production)
65
Q

Malaria
Diagnosis, treatment, prevention, and control
(3)

A

– demonstration of parasites within Wright- or Giemsa-stained red blood cells and serological
tests (but these of little value in acutely ill patient)
– antimalarial drugs (Classic drugs: chloroquine & other quinine based drugs - these block heme
detoxification in Plasmodium food vacuole)
– chemoprophylaxis for individuals traveling to endemic areas, netting, insect repellants

66
Q

Babesia
— to USA
Caused by — species
transmitted by

A

Endemic
Babesia
same Ixodes tick as Borrelia burgdorferi
(Lyme disease agent)

67
Q

Babesia

Infections:

A

subclinical to severe disease; “summer flu
Protozoa infect red blood cells and cause fever upon release
(like malaria, but no intermediate liver stage)
Humans are not the reservoir (white-footed mouse)

68
Q

Babesia

Diagnosis:

A

microscopy of Giemsa-stained blood samples, PCR

69
Q

Babesia

Treatment:

A

clindamycin + quinine (different from malaria)

70
Q

Toxoplasmosis
• caused by —
• transmission by (5)
• Invades —

A

Toxoplasma gondii
ingestion of undercooked meat, congenital transfer, blood transfusion, tissue transplant and ingestion of cat feces
macrophages

71
Q

Toxoplasmosis
— is the definitive
host (sexual cycle)

A

Cat

72
Q 
Toxoplasmosis
This is the most common
mode of transmission:
undercooked meat
containing
A

tissue cysts

73
Q 
Toxoplasmosis
clinical manifestations (3)
A

– usually asymptomatic (>99%) or resembles mononucleosis
– can be fatal in immunocompromised hosts (mass lesions in the brain)
– Congenital infections

74
Q

Toxoplasmosis

• treatment, prevention, and control (3)

A

– antiparasite therapy for immunocompromised patients (pyrimethamine and
– minimizing exposure by: avoidance of raw meat and eggs, washing hands after working
in soil, and cat-handling practices
– Women screened for antitoxoplasma antibody at marriage or very early in pregnancy (if
positive, fetus is protected)

75
Q

Cryptosporidiosis

caused by

A 
Cryptosporidium parvum 
– apicomplexan that forms cysts,
sporozoites, and merozoites
• sporozoites parasitize intestinal
epithelial cells
76
Q

Cryptosporidiosis

• —resistant

A

chlorine

77
Q

Cryptosporidiosis

transmitted from

A 
animal reservoirs in contaminated food or water
– many birds and mammals shed oocysts
in feces
– Also spread from person-to-person in
crowded urban environments (e.g. day
care centers)
– Public water system risks 
– Swimming pools
78
Q

Cryptosporidiosis
clinical manifestations
(3)

A

– diarrhea, abdominal pain, nausea, fever, and fatigue
– usually self-limiting
– can be fatal in late stage AIDS patients and other immunocompromised
individuals

79
Q

Cryptosporidiosis
treatment, prevention, and control
(2)

A

– microscopic examination of stools

– symptomatic/supportive therapy

Microbiology (42 decks)

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