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Microbiology > 5.51 > Flashcards

5.51 Flashcards

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
Hemoflagellate Diseases | • caused by
flagellated protozoa
26
Hemoflagellate Diseases | – two major groups (2)
* leishmanias | * trypanosomes
27
Hemoflagellate Diseases | • transmitted by bites of
infected arthropods | • infect blood and tissues of humans
28
Trypanosomes hemoflagellates important --- pathogens
blood
29
African trypanosomiasis • African sleeping sickness • transmitted by
tsetse flies | – reservoirs included domestic cattle and wild animals
30
African trypanosomiasis | • Chronic bloodstream infection with
bouts of parasitemia
31
African trypanosomiasis | • CNS invasion after
months to years
32
African trypanosomiasis | clinical manifestations
– 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
African trypanosomiasis | • diagnosed by
observation of motile parasites in blood
34
African trypanosomiasis | • drug therapy during systemic stage but not as effective when
CNS | involved. Vaccine not useful due to antigenic variation.
35
tsetse fly | 2
• Intermediate host between animal reservoir & humans • Determines disease range
36
Chagas disease • American trypanosomiasis (Latin America; sporadic in southern USA) • 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
37
Chagas disease heart disease and other disorders due to destruction of parasitized cells in the liver, spleen, lymph nodes, and central nervous system (2)
– Megaesophagus, megacolon (due to damage to nerves in GI tract) – Cardiomyopathy (due to damage to heart muscle)(sudden death from arrhythmia)
38
Chagas disease | tx (2)
• no treatment available for late complications Vaccines not useful because of antigenic variation- genetic switching
39
Chagas disease Vector (2)
• Parasite discharged in feces • Enter human body through bite wound
40
Leishmaniasis | • caused by
Leishmania species (several, with different tissue tropisms)
41
Leishmaniasis | 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)
42
Leishmaniasis | three forms of infection
– mucocutaneous, cutaneous, and visceral
43
visceral •involves •clinical manifestations (2)
tissue macrophage disfunction –intermittent fever and enlargement of spleen or liver –recovery provides permanent immunity
44
mucocutaneous
lesions of mouth, nose, throat and skin that cause extensive scarring and disfigurement
45
cutaneous (2)
``` •papules that develop into crustated ulcers •healing occurs with scarring and permanent immunity ```
46
Leishmaniasis | treatment, prevention, and control (2)
``` Several types of drugs available (including amphotericin B, the polyene anti-fungal agent) – vector and reservoir control, and epidemiological surveillance ```
47
Amoebiasis (amoeboid protozoa) • amoebic --- • caused by
dysentery | Entamoeba histolytica
48
Amoebiasis | • transmission by
ingestion of cysts
49
Amoebiasis | clinical manifestations
– asymptomatic to fulminating dysentery, exhaustive diarrhea, and abscesses of liver, lungs, and brain
50
Amoebiasis treatment, prevention, and control (3)
``` – 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
Phylum Apicomplexa • lack --- organelles • all have --- complex
locomotor | apical
52
Phylum Apicomplexa lack locomotor organelles – except for (2)
male gametes and | zygotes
53
Phylum Apicomplexa all have apical complex – arrangement (3) at one end of cell
fibrils, tubules, | vacuoles, and other organelles
54
Apicomplexan life cycles | involves (2)
• involves two different hosts (usually mammal and mosquito) • involves both asexual and sexual phases
55
Apicomplexan life cycles – schizogony (2)
• asexual phase • rapid series of mitotic events producing infective organisms
56
Apicomplexan life cycles | – oocyst (3)
• produced during sexual phase • thick-walled, diploid structure • undergoes meiosis to produce haploid spores
57
``` Important sporozoan genera (sporozoan = apicomplexan) • Plasmodium – • Cryptosporidium – • Toxoplasma – ```
malaria cryptosporidiosis toxoplasmosis
58
Malaria | • caused by four species of
Plasmodium (Plasmodium falciparum is | most virulent; others are P. vivax, P. malariae, and P. ovale)
59
Malaria | • transmitted by
bite of an infected female Anopheles mosquito
60
Malaria | Reservoir:
humans
61
Malaria | Intermediate host:
humans | asexual reproduction
62
Malaria | Definitive host:
mosquito | sexual reproduction
63
``` Malaria P. vivax and P. ovale form --- (dormant forms) within liver cells. These cause --- (months to years after initial disease). ```
hypnozoites | recurrent malaria
64
Malaria | clinical manifestations
``` periodic attacks of chills and fever (coincides with RBC lysis and merozoite release, which stimulates cytokine production) ```
65
Malaria Diagnosis, treatment, prevention, and control (3)
– 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
Babesia --- to USA Caused by --- species transmitted by
Endemic Babesia same Ixodes tick as Borrelia burgdorferi (Lyme disease agent)
67
Babesia | Infections:
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
Babesia | Diagnosis:
microscopy of Giemsa-stained blood samples, PCR
69
Babesia | Treatment:
clindamycin + quinine (different from malaria)
70
Toxoplasmosis • caused by --- • transmission by (5) • Invades ---
Toxoplasma gondii ingestion of undercooked meat, congenital transfer, blood transfusion, tissue transplant and ingestion of cat feces macrophages
71
Toxoplasmosis --- is the definitive host (sexual cycle)
Cat
72
``` Toxoplasmosis This is the most common mode of transmission: undercooked meat containing ```
tissue cysts
73
``` Toxoplasmosis clinical manifestations (3) ```
– usually asymptomatic (>99%) or resembles mononucleosis – can be fatal in immunocompromised hosts (mass lesions in the brain) – Congenital infections
74
Toxoplasmosis | • treatment, prevention, and control (3)
– 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
Cryptosporidiosis | caused by
``` Cryptosporidium parvum – apicomplexan that forms cysts, sporozoites, and merozoites • sporozoites parasitize intestinal epithelial cells ```
76
Cryptosporidiosis | • ---resistant
chlorine
77
Cryptosporidiosis | 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 (e.g. day care centers) – Public water system risks – Swimming pools ```
78
Cryptosporidiosis clinical manifestations (3)
– diarrhea, abdominal pain, nausea, fever, and fatigue – usually self-limiting – can be fatal in late stage AIDS patients and other immunocompromised individuals
79
Cryptosporidiosis treatment, prevention, and control (2)
– microscopic examination of stools | – symptomatic/supportive therapy

Microbiology (42 decks)

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