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microbiology > protozoa > Flashcards

protozoa Flashcards

1
Q 
Protozoa
as a group? 
related by?
where they live?
parasitic?
A
  • Diverse group of eukaryotic microbes
  • Related only by their simple organization: unicellular or multicellular without specialized tissues
  • Most are free-living in aquatic environments or on decaying organic matter
  • Some are parasitic
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2
Q

Encystation (many protozoa are capable of this)

A

• formation of a cyst
– resting state with a wall and low metabolic
activity
– function of cysts
• protection from changes in environment
• sites for nuclear reorganization and cell division
• transfer from one host to another

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3
Q

Excystation

A

• escape of vegetative form from cyst
• usually triggered by return to favorable environment
• trophozoite
– vegetative form released by parasitic species
– excystation often triggered by entry into new host

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4
Q

Locomotory Organelles

A 
• some protozoa are
nonmotile
• motile species use one
of following:
– cilia
– flagella
– pseudopodia (s.,
pseudopodium)
• cytoplasmic extensions
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5
Q

Reproduction

A 
• asexual
– usually by binary fission
• mitosis followed by cytokinesis
• sexual
– usually by conjugation
• exchange of gametic nuclei between paired
protozoa of opposite mating types
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6
Q

Zooflagellates, spp

A

Motile due to one or more flagella
Giardia lamblia
Trichomonas vaginalis
Trypanosomes

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7
Q

Giardia lamblia disease

A

giardiasis - gastrointestinal disorder

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8
Q

Trichomonas vaginalis disease

A

trichomoniasis - sexually

transmitted disease

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9
Q

Trypanosomes, class/ disease

A

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

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10
Q

Giardiasis
affects?
most common cause of?

A

gastrointestinal disorder

Most common cause of epidemic waterborne diarrheal disease

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11
Q 
Giardiasis 
caused by? forms? 
transmission?
reservoir?
carriers?
A

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

• transmission usually by cyst-contaminated water
– numerous animal reservoirs
– asymptomatic human carriers are common

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12
Q

Giardiasis clinical manifestations (acute and chronic)

A

– acute giardiasis - severe diarrhea, epigastric pain, cramps, voluminous flatulence,
and anorexia
– chronic gastritis - intermittent diarrhea with periodic appearance and remission of
symptom

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13
Q

giardasis tx, prevention

A

– antiprotozoal agents (metronidazole)

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

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14
Q

Trichomoniasis cause? transmission? form transmitted in?

A

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

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15
Q

Trichomoniasis clinical manifestations

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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16
Q

Trichomoniasis diagnosis and tx? (drug name)

A

observation of parasite in vaginal discharge, semen or urine

– antiparasite therapy (metrodiazole)

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17
Q

Trichomonas tenax

A

resides in mouth
Usually associated with poor oral hygiene
Aspiration associated with pneumonia

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18
Q 
Hemoflagellate Diseases
caused by? 
groups? 
transmitted how?
what do these infect?
A

• caused by flagellated protozoa

– two major groups
• leishmanias
• trypanosomes

  • transmitted by bites of infected arthropods
  • infect blood and tissues of humans
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19
Q

Trypanosomes
flagellum?
pathogens of what?

A

hemoflagellates

important blood pathogens

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20
Q 
african trypanosomiasis
spp?
common name?
transmitted by? 
reservoirs?
affected tissues?
A

Trypanosoma brucei
• African sleeping sickness
• transmitted by tsetse flies – reservoirs included domestic cattle and wild animals

  • Chronic bloodstream infection with bouts of parasitemia
  • CNS invasion after months to years
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21
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

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22
Q

african trypanosomiasis diagnosis

A

diagnosed by observation of motile parasites in blood

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23
Q

african trypanosomiasis tx/ vax

A

drug therapy during systemic stage, but not as effective when CNS involved.
Vaccine not useful due to antigenic variation.

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24
Q 
Chagas disease
additonal name?
transmitted by? 
resivoirs?
infection age in endemic regions? 
early disease? % with later complications?
A

American trypanosomiasis
transmitted by 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

•

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25
Q

chagas disease leads to? how?

A

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

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

26
Q

chagas disease agent/ vector

A

Trypanosoma cruzi
• Parasite discharged in feces of kissing bug
• Enter human body through bite wound

27
Q

chagas tx and vax

A

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

28
Q

Leishmaniasis cause?
transmitted?
reservoirs?
macrophages?

A

• caused by Leishmania species (several, with different tissue tropisms)
• transmitted by sand flies when they take a blood meal (usually tropical)
– animal reservoirs include canines and rodents

Leishmania survives and differentiates in macrophages (superoxide dismutase)

29
Q

Leishmaniasis forms

A

three forms of infection

– mucocutaneous, cutaneous, and visceral

30
Q

mucocutaneous Leishmaniasis

A

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

31
Q

cutaneous Leishmaniasis

A 
•papules that develop
into crustated ulcers
•healing occurs with
scarring and
permanent immunity
32
Q

visceral Leishmaniasis
involves?
clinical manifesations?
immunity?

A

•involves tissue macrophage disfunction

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

33
Q

treatment, prevention, and control of Leishmaniasis

A

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

34
Q

Amoebiasis cause

transmission

A

• amoebic dysentery
• caused by Entamoeba histolytica
• transmission by ingestion of cysts
l

35
Q

Amoebiasis clinical manifestations

A

asymptomatic to fulminating dysentery, exhaustive diarrhea

and abscesses of liver, lungs, and brain

36
Q

treatment, prevention, and control of Amoebiasis
stool? serological?
drug treatment?
water/food?

A

– observation of trophozoites in fresh warm stools or cysts in ordinary stools, and serological tests
– Metronidazole therapy
– avoiding contaminated water and food and hyperchlorination or iodination of water supplies to destroy waterborne cysts

37
Q

Phylum Apicomplexa
lack?
all have?

A

• lack locomotor organelles
– except for male gametes and zygotes

• all have apical complex
– arrangement fibrils, tubules, vacuoles, and other organelles at one end of cell

Contains materials that are secreted and aid in penetration of host cell

38
Q

Apicomplexan life cycles

A

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

39
Q

asexual phase of apicomplexans

undergoes? produces?

A

– schizogony

• rapid series of mitotic events producing infective organisms

40
Q

sexual phase a apicomplexans
strucure? ploidy?
undergoes?

A

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

41
Q

Important sporozoan genera (sporozoan = apicomplexan) and diseases caused

A
  • Plasmodium – malaria
  • Cryptosporidium – cryptosporidiosis
  • Toxoplasma – toxoplasmosis
42
Q

Malaria
caused by? most virulent?
transmitted?

A
  • caused by four species of Plasmodium (Plasmodium falciparum is most virulent; others are P. vivax, P. malariae, and P. ovale)
  • transmitted by bite of an infected female Anopheles mosquito
43
Q

malaria resivoir, host types

A

Reservoir: humans
Intermediate host: humans asexual reproduction
Definitive host: mosquito sexual reproduction

44
Q

recurrent malaria

A

P. vivax and P. ovale form hypnozoites (dormant forms) within liver cells.
These cause recurrent malaria (months to years after initial disease).

45
Q

malaira clinical manifestations

A

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

46
Q

malaria cycle in humans

A

Hepatocellular cycle Released from liver as merozoities
8-14 days

erythocytic cyle in blood, 2-3 days, asexual reproduction

Small number of merozoites develop into gametocytes

47
Q

malaria cycle in mosquitoes

A

Meiotic division generates sporozoites which can penetrate host cells

48
Q

Malaria

Diagnosis, treatment, prevention, and control

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 detox
– chemoprophylaxis for individuals traveling to endemic areas, netting, insect repellants

49
Q

malaria early ring forms

A
50
Q

Babesia

A

Endemic to USA
Caused by Babesia species transmitted by same Ixodes tick as Borrelia burgdorferi
(Lyme disease agent)

51
Q

Babesia infections
severity? common name?
protozoa infect what? result?

A

subclinical to severe disease; “summer flu”

Protozoa infect red blood cells and cause fever upon release (like malaria, but no intermediate liver stage)

52
Q

babesia resivoir

A

Humans are not the reservoir (white-footed mouse)

53
Q

babesia diagnosis and treatment

A

Diagnosis: microscopy of Giemsa-stained blood samples, PCR, ring forms present
Treatment: clindamycin + quinine (different from malaria)

54
Q

Toxoplasmosis
caused by?
transmission?
invades what cells?

A
  • caused by Toxoplasma gondii
  • transmission by ingestion of undercooked meat, congenital transfer, blood transfusion, tissue transplant and ingestion of cat feces
  • Invades macrophages
55
Q

Toxoplasmosis cycle

A
56
Q

toxoplasmosis clinical manifestations
% symptomatic? can resemble?
fatal in what population? (how)
congenital?

A

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

57
Q

Toxoplasmosis treatment, prevention, and control

A

– antiparasite therapy for immunocompromised patients
– 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)

58
Q 
Cryptosporidiosis
caused by? forms? 
parasitize what cells? 
resistant to? 
transmission?
A
  • caused by Cryptosporidium parvum – apicomplexan that forms cysts, sporozoites, and merozoites
  • sporozoites parasitize intestinal epithelial cells
  • chlorine-resistant

• transmitted from 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
– Public water system risks/ pools

59
Q

Cryptosporidiosis
clinical manifestations
limited?
fatal in what populations?

A

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

60
Q

Cryptosporidiosis diagnosis and treatment

A

– microscopic examination of stools

– symptomatic/supportive therapy

microbiology (42 decks)

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