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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
chagas disease leads to? how?
• 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
chagas disease agent/ vector
Trypanosoma cruzi • Parasite discharged in feces of kissing bug • Enter human body through bite wound
27
chagas tx and vax
no treatment available for late complications Vaccines not useful because of antigenic variation - genetic switching
28
Leishmaniasis cause? transmitted? reservoirs? macrophages?
• 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
Leishmaniasis forms
three forms of infection | – mucocutaneous, cutaneous, and visceral
30
mucocutaneous Leishmaniasis
lesions of mouth, nose, throat and skin that cause extensive scarring and disfigurement
31
cutaneous Leishmaniasis
``` •papules that develop into crustated ulcers •healing occurs with scarring and permanent immunity ```
32
visceral Leishmaniasis involves? clinical manifesations? immunity?
•involves tissue macrophage disfunction –intermittent fever and enlargement of spleen or liver –recovery provides permanent immunity
33
treatment, prevention, and control of Leishmaniasis
– Several types of drugs available (including amphotericin B, the polyene anti-fungal agent) – vector and reservoir control, and epidemiological surveillance
34
Amoebiasis cause | transmission
• amoebic dysentery • caused by Entamoeba histolytica • transmission by ingestion of cysts l
35
Amoebiasis clinical manifestations
asymptomatic to fulminating dysentery, exhaustive diarrhea | and abscesses of liver, lungs, and brain
36
treatment, prevention, and control of Amoebiasis stool? serological? drug treatment? water/food?
– 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
Phylum Apicomplexa lack? all have?
• 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
Apicomplexan life cycles
• involves two different hosts (usually mammal and mosquito) • involves both asexual and sexual phases – schizogony – oocyst
39
asexual phase of apicomplexans | undergoes? produces?
– schizogony | • rapid series of mitotic events producing infective organisms
40
sexual phase a apicomplexans strucure? ploidy? undergoes?
– oocyst • produced during sexual phase • thick-walled, diploid structure • undergoes meiosis to produce haploid spores
41
Important sporozoan genera (sporozoan = apicomplexan) and diseases caused
* Plasmodium – malaria * Cryptosporidium – cryptosporidiosis * Toxoplasma – toxoplasmosis
42
Malaria caused by? most virulent? transmitted?
* 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
malaria resivoir, host types
Reservoir: humans Intermediate host: humans asexual reproduction Definitive host: mosquito sexual reproduction
44
recurrent malaria
P. vivax and P. ovale form hypnozoites (dormant forms) within liver cells. These cause recurrent malaria (months to years after initial disease).
45
malaira clinical manifestations
periodic attacks of chills and fever (coincides with RBC lysis and merozoite release, which stimulates cytokine production)
46
malaria cycle in humans
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
malaria cycle in mosquitoes
Meiotic division generates sporozoites which can penetrate host cells
48
Malaria | Diagnosis, treatment, prevention, and control
– 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
malaria early ring forms
50
Babesia
Endemic to USA Caused by Babesia species transmitted by same Ixodes tick as Borrelia burgdorferi (Lyme disease agent)
51
Babesia infections severity? common name? protozoa infect what? result?
subclinical to severe disease; “summer flu" Protozoa infect red blood cells and cause fever upon release (like malaria, but no intermediate liver stage)
52
babesia resivoir
Humans are not the reservoir (white-footed mouse)
53
babesia diagnosis and treatment
Diagnosis: microscopy of Giemsa-stained blood samples, PCR, ring forms present Treatment: clindamycin + quinine (different from malaria)
54
Toxoplasmosis caused by? transmission? invades what cells?
* caused by Toxoplasma gondii * transmission by ingestion of undercooked meat, congenital transfer, blood transfusion, tissue transplant and ingestion of cat feces * Invades macrophages
55
Toxoplasmosis cycle
56
toxoplasmosis clinical manifestations % symptomatic? can resemble? fatal in what population? (how) congenital?
usually asymptomatic (>99%) or resembles mononucleosis – can be fatal in immunocompromised hosts (mass lesions in the brain) – Congenital infections
57
Toxoplasmosis treatment, prevention, and control
– 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
``` Cryptosporidiosis caused by? forms? parasitize what cells? resistant to? transmission? ```
* 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
Cryptosporidiosis clinical manifestations limited? fatal in what populations?
– diarrhea, abdominal pain, nausea, fever, and fatigue – usually self-limiting – can be fatal in late stage AIDS patients and other immunocompromised individuals
60
Cryptosporidiosis diagnosis and treatment
– microscopic examination of stools | – symptomatic/supportive therapy

microbiology (42 decks)

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