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Infectious Disease and Microbiology > Eukaryotic Pathogens: Fungal & Protozoa > Flashcards

Eukaryotic Pathogens: Fungal & Protozoa Flashcards

1
Q

Fungi include

A
  • yeasts: normally grow as single cells

- molds: form branching filaments called hyphae with or without septa (cross walls)

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2
Q

mycelia

A

visible masses formed by intertwining hyphae

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3
Q

common fungal pathogens

A

Most fungi (5.1 million) are harmless to humans

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4
Q

Fungi are also important in medicine as both

A
  • agents of disease

- chemotherapy

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5
Q

only about ____ fungal species cause ______

A

50, disease

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6
Q

In healthy individuals the

incidence of serious fungal infections is

A

low
-certain superficial
fungal infections are fairly common (for example, Athlete’s foot)

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7
Q

Fungal infections can be

A

systemic

-reaching even the deepest of internal tissues

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8
Q

Pathogenic fungi

A

Common fungal pathogens include both Yeast and Molds

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9
Q

many pathogenic fungi are

A

Dimorphic

-they can exists as either Yeast or in Filamentous form (Dimorphism)

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10
Q

Fungi cause disease through three major mechanisms

A
  • Inappropriate immune responses
  • Toxin production
  • Fungal Infections: Mycosis
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11
Q

some fungi trigger

A

immune responses

  • result in allergic (hypersensitivity reactions)
  • following exposure to specific fungal antigens
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12
Q

Aspergillus sp

A 
common saprophyte
-often found in nature as a leaf mold
-produces potent allergens
-triggering asthma attacks or
other hypersensitivity reactions in susceptible
individuals
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13
Q

Mycotoxins e.g. Aflatoxin

A

Fungal disease may occur from its production
-highly toxic and
are also carcinogenic
-can produce liver damage in humans including cirrhosis and liver cancer
-adults aren’t seriously affected by low-level

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14
Q

Mycosis

A

growth of a fungus on/or in the body

-fungal infections that range in severity from superficial to life-threatening

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15
Q

superficial mycoses

A

fungus infects only the surface layers of skin, hair or nails
-quite common

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16
Q

subcutaneous mycoses

A

infections of deeper layers of skin
-typically caused by
different fungi than superficial infections
-Treated with topical drugs.

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17
Q

Systemic mycoses

A

are the most serious categories of fungal infections
- characterized by fungal growth in internal organs of the body
-primary or secondary infections
-far less common
-primarily
affects the elderly or otherwise immune compromised patients
-target those of any age whose Immune System have
been impaired or destroyed

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18
Q

primary infection

A

otherwise normal healthy individual is infected with the fungal pathogen
-rather uncommon

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19
Q

secondary infection

A

occurs in a host that harbors a predisposing condition
-makes the individual more
susceptible to infection

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20
Q

mycoses

A

two extremes of fungal infections are the superficial and the Systemic mycoses

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21
Q

as people age

A

cell-mediated immunity slowly declines due to surgeries,
transplantations, immunosuppressive drug treatments for rheumatism and
autoimmune diseases, and the onset of other conditions, such as pulmonary decline, diabetes and cancer

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22
Q

Trichophyton

A

cause infections of the feet (Athlete’s foot)

  • cause flaking and itchy skin
  • easily transmitted by cells or spores of the pathogen
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23
Q

superficial mycosis can be treated with

A

topical antifungal creams or liquid aerosols

-Miconazole nitrate or Griseofulvin

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24
Q

jock itch

A

infection of groin, skin folds or anus

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25
Q

ringworm

A

fungal infection
-typically localized to scalp or extremities
-infection causes hair loss and inflammation like
reactions

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26
Q

dermatophytes

A

live on keratin

-found in skin, hair and nails

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27
Q

Sporotrichosis

A

occupational hazard of agricultural workers,
miners, gardeners, and others who come into close and continual contact with the soil
-causal organism: Sporothrix schenckii

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28
Q

Chromoblastomycosis

A

due to pathogenic fungal growth in both surface and subcutaneous skin layers
-form crusty, wartlike lesions on the hand or leg

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29
Q

Both Sporotrichosis and Chromoblastomycosis

A

can be treated with oral administration of Azoles

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30
Q

systemic fungal pathogens

A

normally live in soil, and humans become infected by inhaling airborne
spores that later germinate and grow in the lungs

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31
Q

histoplasmosis

A

caused by Histoplasma capsulatum
-primarily a disease of rural
areas in Midwestern states of the US

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32
Q

Coccidioidomycosis

A

caused by Coccidioides immitis

-more restricted to the desert regions of the southwestern US

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33
Q

Blastomycosis

A

caused by Blastomyces dermatitidis

-Prevalent in more tropical climates

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34
Q

Cryptococcosis

A

caused by the dimorphic yeast Cryptococcus neoformans
-can occur in virtually any
organ of the body
-major mycosis seen in HIV/AIDS patients producing fungal meningitis

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35
Q

Candida auris

A

drug resistant germ that spreads in healthcare facilities

  • can cause bloodstream infection and even death
  • often resistant to medicines
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36
Q

candida auris treatment

A

Echinocandins

  • systemic infections in immunocompromised patients
  • Inhibit 1,3 b-D glucan synthase (no present in mammals), the enzyme that forms Glucan polymers in fungal cell wall
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37
Q

Histoplasma capsulatum

A

Causative agent: Histoplasma capsulatum
-causes a systemic
endemic Mycosis called Histoplasmosis
-thermally dimorphic ascomycete
-can survive at 2 different temperatures
-considered a facultative intracellular fungi that circulates in the
reticuloendothelial system
-remains in a saprophytic Mycelial mold form, but
at mammalian body temperature grows as parasitic yeast
-found in temperate climates

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38
Q

Histoplasma capsulatum

A

endemic to Ohio, Missouri, Iowa, Indiana and Mississippi River valleys in the U.S
-can bind directly to the CD11/CD18 integrins on Macrophages

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39
Q

Histoplasma clinical features

A

In the lungs, inhaled Mycelial fragments and microconidia of Histoplasma capsulatum are ingested by
resident macrophages

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40
Q

pathogenic yeast phase

A

occurs inside the

macrophages, mostly due to the temperature change

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41
Q

Histoplasma capsulatum Treatment

A

-self limited in majority of cases
-Clinical symptoms develop mostly in immunocompromised
individuals
-Severe cases of Acute Histoplasmosis and All cases of Chronic and disseminated disease require treatment with antifungal drugs
-Amphotericin B followed with Itraconazole (inhibits the fungalmediated
synthesis of Ergosterol, via inhibition of lanosterol 14α-demethylase
-Fluconazole and Ketoconazole or a broad spectrum antifungal drug, Imidazole

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42
Q

ergosterol

A

sterol found in fungi

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43
Q

parasitism

A

symbiotic relationship between two organisms, the parasite and the host
-parasite derives essential nutrients from the host and may have little or no harmful effect on the
host
-parasitic infections can be visceral or infec blood

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44
Q

visceral

A

inducing vomiting, diarrhea, and other intestinal symptom

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45
Q

infection of blood

A

internal tissues

46
Q

visceral parasitic infections

A

Amoeba and Ciliates: Entamoeba, Naegleria, and Balantidium

47
Q

Entamoeba and Naegleria

A

belong to a large group of protists that move by extending

lobe-shaped pseudopodia, the Amoebozoa

48
Q

Entamoeba Histolytica

A

pathogenic protist transmitted to humans primarily through contaminated water and sometimes food with
human feces
-Anaerobic and produces resistant cysts, which are the means of transmission
-Infection can be asymptomatic or lead to diarrhea and dysentery

49
Q

ingested cysts

A

germinate to form amoebae that grow both on and in intestinal mucosa

50
Q

dysentery

A

infection of the intestines resulting in severe
diarrhea with the presence of blood and mucus in the feces
-If untreated, invasive cells can invade the liver and
occasionally the lungs and brain
diagnosis: stool examination for Cysts and parasites
-Can be treated with amoebicidal drugs e.g. Metronidazole and/or Tinidazol, followed
by intraluminal agent (Paromomycin)

51
Q

Naegleria fowleri

A

Known as “Brain-eating amoeba
-free-living amoeba found in soil and water runoff that can also cause amebiasis
-Infections usually result from swimming or bathing in warm or hot (up to 1150F, 460C) freshwater, soil-contaminated water
sources
-not in salt waters
-Enters the human body through the nose and burrows directly
into the brain

52
Q

You _____ be infected with Naegleria fowleri by drinking

contaminated _____

A

can’t, water

53
Q

Meningoencephalitis

A

extensive

hemorrhage and brain damage

54
Q

initial symptoms of Naegleria fowleri

A

headache, fever, nausea, or
vomiting. Later symptoms can include stiff neck, confusion, lack of attention to people and surroundings, loss of balance, seizures, and hallucinations

55
Q

diagnosis of Naegleria fowleri

A

requires observation of the amoebae in CSF
(Cerebrospinal fluid)
-Drug treatment is effective if infections are identified early

56
Q

balantidium coli

A

ciliated intestinal human and swine parasite that
alternates between the cyst and trophozoite stage
-only known ciliated parasite of humans
-infections caused by cysts
-transmitted to humans through fecally contaminated food and water
-germinates in colon and infects mucosal tissues

57
Q

balantidium coli symptoms

A

resemble those of amebiasis:
diarrhea, dysentery, abdominal pain, nausea, vomiting
-infected patient usually experienced a spontaneous recovery or may become an
asymptomatic carrier

58
Q

three medications often used to treat Balantidium coli

A

Tetracycline, Metronidazole,

and Iodoquinol

59
Q

infective balantidium coli

A

spherical

-diagnostically found in feces of infected individuals

60
Q

non-infective balantidium coli

A

occasionally found in feces,

often found in tissue biopsis of infected individuals

61
Q

Diplomonads & Parabasalids

A

Key genera: Giardia, Trichomonas
-unicellular, flagellated, non-phototrophic protists that lack chloroplasts
-Live in anoxic habitats, such as animal intestines, either
symbiotically or as parasites, conserving energy for fermentation

62
Q

diplomonads

A

-Have two nuclei of equal size
– Have mitosomes, limited mitochondria lacking e- transport proteins and enzymes of the citric acid cycle.
– Cause of Giardiasis, a common waterborne diarrheal disease

63
Q

parabasalids

A

Contain a parabasal body that gives structural support to the Golgi complex.
– Lack mitochondria, but have hydrogenosomes for anaerobic metabolism
– Live in the intestinal and urogenital tract as parasites or as commensal symbionts (Trichomona vaginalis, cause a sexually transmitted disease in humans: Trichomoniasis.
– Genomes lack introns, but is huge for a parasitic organism showing evidence of horizontal gene transfer from bacteria

64
Q

Giardiasis

A

Giardia intestinalis (also called Giardia lamblia)
-It is a Flagellated anaerobic parasite
– Has mitosomes
– Produces highly resistant cysts
-It is typically transmitted to humans in fecally contaminated water
and causes an acute gastroenteritis, giardiasis

65
Q

giardiasis characterized by

A

Explosive foul-smelling diarrhea, intestinal
cramps, nausea, weight loss, and malaise
– Many individuals exhibit no symptoms and can act
as carriers

66
Q

What distinguishes diarrhea from giardiasis?

A

foul-smelling diarrhea and the absence of fecal blood

67
Q

Giardia Intestinalis

A

causes a significant number of drinking water infectious disease outbreaks in the US
-thick-walled cysts are resistance to chlorine
-most outbreaks associated with water systems
that use only chlorination as a mean of water purification. -Water subjected to proper clarification and filtration
followed by chlorination or other disinfection should be free of giardia cysts.
-Most surface water sources (lakes, ponds, and streams) contain Giardia cysts as beavers and muskrats are carriers
(remember Raw Water

68
Q

Trichomonas vaginalis

A

Causes a sexually transmitted infection, Trichomoniasis
-Flagellated anaerobic parasite
-Has hydrogenosomes (membrane enclosed organelle)
-Transmitted person-to-person by sexual intercourse
-Can survive on moist surfaces for several hours
-Can be transmitted by toilet seats, sauna benches,
and towels
-Can survive for up to a day in urine or semen
-asymptomatic in males
-Presents a yellowish vaginal discharge that causes a
persistent itching, and burning in women
-diagnosed by observation of the
motile protists in a wet mount of fluid discharged from
the patient.

69
Q

What drug is used in treatment of Trichomonas vaginalis?

A

Antiprotozoal drug Metronidazole

70
Q

Cryptosporidium, Toxoplasma, and Cyclospora are genera of

A

Parasitic coccidia (which group among the alveolates)

  • Transmitted to humans through fecally contaminated food or water
  • can trigger serious bouts of diarrhea, or in the case of Toxoplasma, serious internal organ damage
71
Q

Cryptosporidium parvum

A

-Protist that lives as a parasite in warm-blooded
animals in particular cattle (a) Trophozoites.
-Produces thick-walled cells (oocysts) that are shed in the feces of infected animals
-The oocysts are transmitted in fecally
contaminated water
-Oocysts are highly resistant to chlorine and UV
radiation
-sedimentation and filtration
methods are most effective at removal

72
Q

Cryptosporidium parvum treatment

A

Nitazoxanide for treatment of diarrhea

73
Q

Alveolates (Apicomplexans)

A

Obligate parasites of animals that causes severe human diseases such as Malaria, toxoplasmosis and coccidiosis

  • Characterized by nonmotile adult stages, nutrients are taken up in soluble form across the cytoplamic membrane as in bacteria and fungi
  • Produce structures called sporozoites
  • Contain apicoplasts
74
Q

sporozoites

A

which function in

transmission of the parasite to a new host.

75
Q

apicoplasts

A

chloroplasts that lack

pigments and phototrophic capacity, carry out fatty acid, and heme biosynthesis

76
Q

toxoplasmosis

A

due to infection with Toxoplasma gondii
-Definitive host of the parasite: cats
-Symptoms: Most primary infections produce no
symptoms. The time between exposure to the parasite and
symptom development is 1 - 2 weeks.
-disease can
affect the brain, lung, heart, eyes, or liver.

77
Q

Coccidiosis:

A

parasitic disease of the intestinal tract
produced by coccidian protozoa
- disease spreads from
one animal to another by contact with infected feces

78
Q

Toxoplasma gondii (Toxoplasmosis)

A

Protist that lives as a parasite in warm-blooded animals
–Produces oocysts that are shed in the feces of infected animals
– The oocysts are transmitted by cats (obligate host)
-humans and other
animals are only incidental hosts.
-Also by undercooked meat: beef, pork or lamb

79
Q

Toxoplasmosis is

A

mainly asymptomatic
-can damage eyes, brain, and other organs in
immune-compromised individuals
-first time infection with T. gondii in expectant
mothers can lead to birth defects in newborns

80
Q

Toxoplasma gondii causative agent

A

protozoan intracellular parasite

81
Q

Toxoplasma gondii entry and spread within the body

A

Oocytes are shed in the feces of cats and may survive up to 18 months in the environment.
- During this time they may be ingested by other animals such as rodents
-Within the intestine of these intermediate hosts, the
oocytes release sporozoites that invade the intestinal
epithelium and multiple to form Tachyzoites

82
Q

Tachyzoites

A

may spread to local cells or pass via the lymphatics to regional lymph nodes and then to elsewhere in the body
-At each tissue Tachyzoites multiply to form tissue cysts

83
Q

Toxoplasma gondii person to person spread

A

Humans can pass infection vertically from pregnant mother to fetus but are NOT a source of horizontal transmission

84
Q

Toxoplasma gondii clinical presentation

A

pregnant mothers acquire Toxoplasma gondii infection
during their pregnancy there is a risk of transplacental
transfer of Tachyzoites
-If the infection had been acquired before pregnancy
there is the possibility that reactivation of tissue
cysts will release Tachyzoites during pregnancy

85
Q

The greatest risk of congenital abnormality is with infections between __
and __ weeks gestation

A

10, 24

86
Q

Hydrocephalus

A

a build-up of fluid in the cavities deep within the brain

87
Q

microcephaly

A

disturbance

of brain development can stunt its growth

88
Q

chorioretinitis

A

inflammation of the retina in the eye

-commonest manifestation of toxoplasma gondii

89
Q

Toxoplasma gondii diagnosis

A

main diagnostic test is serology:
-Currently ELISA techniques are used to assay for anti-Toxoplasma IgG and IgM
-Formerly live or formalin-fixed tachyzoites were used in neutralization, immunofluorescence , and
agluttination assays
-useful in excluding T. gondii infection if negative on two occasions 3 weeks apart

90
Q

Toxoplasma gondii management

A

Pyrimethamine and Sulfadiazine
-both are folate antagonist
effective in killing tachyzoites, but do not
clear tissue cysts
-Side effects: severe BM suppression, add Folic Acid
supplements

91
Q

Management of toxoplasmosis during pregnancy

A

-is challenging: the drug used in pregnant women is Spiramycin (macrolide antibiotic: protein synthesis inhibitor)

92
Q

Spiramycin:

A

does not cross placenta and is only used to kill tachyzoites before they can transfer to the fetus

93
Q

Malaria

A

-protist disease caused by Plasmodium spp, member of the alveolate group.
-Several species of the protozoal genus cause malaria-like diseases in warm-blooded hosts
-Has a complex life cycle that includes female Anopheles mosquitoes as vectors
-WHO estimates that around 350 million people infected worldwide
– Each year over 1 million people die from Malaria
– Generally found in tropical and subtropical regions
– Four species of Plasmodium: P. vivax, P. falciparum, P. ovale and P. malariae -cause most human malaria.
– The most widespread disease is caused by P. vivax, whereas the most serious disease is caused by P. falciparum

94
Q

Life cycle of Plasmodium requires

A

both a warm-blooded host and the mosquito vector

95
Q

plasmodial life cycle in RBC

A

proceeds with repeated division, growth, and release of Merozoites:
results in the destruction of
the host RBC
-Vomiting and severe headache

96
Q

defining clinical symptoms

of malaria

A

chills followed by fever of up to 400C (104F)

97
Q

Malaria typically causes

A

Anemia and some enlargement of the spleen (splenomegaly

98
Q

drugs used to prevent and treat plasmodium/malaria

A
  • Chloroquine (kills merozoites within RBC but does not kills sporozoites) -Primaquine eliminates sporozoites of P. vivax and P. ovale that may remain in the liver cells
  • treatment with both drugs effectively cures most malaria
99
Q

Malaria can be controlled by

A

draining swamps, mosquito nets or eliminating mosquitoes with insecticides

100
Q

Plasmodium spp causative agent

A

eukaryotic protozoan that infects the RBC of humans. –vector for Malaria is the female Anopheles mosquito.

101
Q

Plasmodium spp Entry and spread within the body

A

transmission stage is the

sporozoite, which is injected into the bloodstream of a human when the female Anopheles mosquito takes a blood meal

102
Q

plasmodium person to person spread

A

sporozoites are injected into an individual when an infected female Anopheles mosquito feeds and the whole cycle starts again

103
Q

plasmodium Non-mosquito spread

A

malaria can also be transmitted through blood transfusion, hypodermic needle sharing or accidents, and from mother to fetus

104
Q

epidemiology of malaria

A

Global incidence is estimated to be 350-500 million cases each year, -300 million
carriers of the parasite
-Most malaria infections and death occur in sub-Saharan Africa
-account for 80%
of all clinical cases and about 90% of all people that carry the parasite

105
Q

What provides protection against the plasmodium?

A

Sickle cell trait (heterozygous for HbS

  • G6PD deficiency confers resistance to malaria
  • alpha and in a minor degree beta-Thalassemia
106
Q

plasmodium diagnosis

A

-Blood film: the morphological appearance of the trophozoite (or gametocyte) can be used to identify the species of malaria.
-Serology: detection of antibodies or antigen (used for
rapid identification of acute cases.
-PCR or DNA probes.

107
Q

plasmodium treatment

A

-Drug treatment of the patients with infection
+target the RBC stage of the infection e.g. Chloroquine x 3 days followed by Primaquine x 14
days).
-prevention and control of the vector (mosquito)

108
Q

Euglenozoans

A

Key genera: Trypanosoma, Euglena
-Unicellular free-living or parasitic flagellated eukaryotes that includes the kinetoplastids and euglenids.
– Have a crystalline rod in their flagella

109
Q

Kinetoplastids

A

Named for the presence of the kinetoplast, a mass of circular DNA (kDNA) present in their single large mitochondrion
-Live primarily in aquatic habitats feeding on
bacteria
-Some species are parasites causing serious diseases in humans
- Trypanosoma brucei causes African sleeping sickness, a chronic an usually fatal human
disease
-parasite lives and grows in the bloodstream later stages of the disease it invades the central nervous system
-transmitted from host-to-host by the tsetse-fly

110
Q

American trypanosomiasis (Chagas disease)

A

Trypanosoma cruzi

  • acute form usually goes unnoticed and may present as a localized swelling at the site of entry
  • chronic form may develop 10 to 20 years after infection
  • form affects internal organs
  • Affected people may die from congestive heart failure.
  • Vector: reduviid bug or triatomine bug (kissing bug

Infectious Disease and Microbiology (9 decks)

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