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Microbiology Exam III > Parasitic Infections GI Tract > Flashcards

Parasitic Infections GI Tract Flashcards

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1
Q

Protozoa (Classes)

A
  • Eukaryotes (just like us)
  • Four classes, based on MOTILITY:
    1) Ameba - pseudopodia
    2) Flagellates - flagella
    3) Sporozoans - gliding
    4) Cilitates - cilia
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2
Q

Protozoa (Characteristics)

A
  • Most protozoa reproduce asexually via BINARY FISSION
  • Some sporozoans can reproduce asexually via SCHIZOGONY and/or sexually via SPOROGONY
  • Many produce CYST forms (resting/dormant form), which protect them from the environment and aid in transmission
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3
Q

Amebiasis: Entamoeba histolytica (Life Cycle)

A

Exists in Ameoboid and Cyst forms

1) Cyst form is ingested from the environment
2) Ameoboid form comes out and penetrates the wall, DISSEMINATES, and gets into the bloodstream, causing disease of the brain, liver, etc.
3) PMNS and lysing cells are attracted, causing:
a. Amebic collitis with “flask-shaped ulcers”
b. Liver abscess
c. Other abscesses (brain, etc.)
d. Ameboma

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4
Q

Amebiasis: Entamoeba histolytica (Transmission)

A
  • Fecal-oral transmission*
  • Ingestion of CYSTS
    a) Trophozoites WILL NOT SURVIVE in environment or gastric acidity, so they are NOT INFECTIOUS
    b) Symptomatic vs. Asymptomatic Patients
  • Symptomatic: shed NON-INFECTIOUS form, so not as infections
  • Asymptomatic: shed INFECTIOUS CYST FORM, so they are at greater risk for transmitting disease
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5
Q

Amebiasis: Entamoeba histolytica (Intestinal Disease)

A
  • Gastrointestinal disease
  • 95-100% of symptomatic patients will present visible or microscopic BLOOD IN THEIR STOOL (DYSENTERY)

Unlike bacterial dysentery, fever is RARE

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6
Q

Amebiasis: Entamoeba histolytica (Invasive Disease)

A

-Penetration of intestinal wall by trophozoites
FLASK-SHAPED LESION
-Spread via bloodstream
Liver abscess- abdominal pain, fever, elevated WBC count

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7
Q

Amebiasis: Entamoeba histolytica (Diagnosis and Control/Prevention)

A

Diagnosis:

  • Stool examination or Antigen detection (Intestinal) (e.g. Ova and Parasites “O and P”)
  • Biopsy and Serology (Extra-intestinal)

Control/Prevention:
-Sanitation/hygiene

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8
Q

Cysts vs Trophs: Stool Integrity

A

More Cysts –> More Formed stool

More Trophs –> More Watery stool

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9
Q

Giardiasis: Giardia lamblia (Life Cycle)

A

Cyst and Trophozoite forms (like Entameba)

  • **Unlike Entameba, DO NOT invade the mucosa, rather, just adhere to the surface
  • Just get diarrhea, NOT dysentery

***Fecal-Oral Transmission

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10
Q

Giardiasis: Giardia lamblia (Common Groups Infected)

A

Kids: Daycare centers

Adults: Recreational exposure in the water; swallowing lake water contaminated with stool

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11
Q

Giardia lamblia: Trophozoite Form

A

Trophozoite:

  • 5 to 15 um x 9 to 21 um
  • Teardrop-shaped
  • Two nuclei
  • Four pairs of flagella
  • Claw-shaped median bodies
  • Ventral disk
  • Tumbling or swimming motion with synchronous beating of posterior flagella
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12
Q

Giardia lamblia: Cyst Form

A

Cyst:

  • 6 to 10 um x 8 to 12 um
  • Oval, smooth-walled
  • One or two intracystic trophozoites with identifiable nuclei with central karyosomes
  • Prominent transverse claw-shaped median bodies and longitudinal axostyle
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13
Q

Giardiasis: Giardia lamblia (Transmission)

A
  • Fecal-oral transmission*
  • Ingestion of CYSTS (contaminated water; peak s in early summer to late fall)
  • Outbreaks in day care centers (Kids and caregivers)
  • Symptomatic vs. Asympatomic
  • Not known if there are animal reservoirs
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14
Q

Giardiasis: Giardia lamblia (Intestinal Disease: Symptoms)

A
  • Sudden onset
  • Diarrhea: foul-smelling, greasy, floating (Cramping, bloating, gas; NO BLOOD; No fever)
  • Infected individuals can shed hundreds of millions (100,000,000) of cyst per day
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15
Q

Giardiasis: Giardia lamblia (Acute vs Chronic, Diagnosis, Control/Prevention)

A

Acute: Weeks

Chronic: Months to Years (Malnutrition due to malabsorption)

Diagnosis:

  • Observing cysts in formed stools or trophozoites in diarrheal stools
  • Fecal antigen detection

Control/Prevention:
-Sanitation/Hygiene (water treatment/filtration when hiking, etc.)

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16
Q

Dientamoeba fragilis: Trophozoite Form

A 
7-12 um
Rounded
One or two (80%) nuclei with four to eight symmetrical chromatin granules
Intracellular vacuoles and bacteria
Best identified in permanent strains
Active pseudopods, but sluggish motility
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17
Q

Dientamoeba fragilis: Cyst Form

A

No cyst form

18
Q

Chilomastix mesnili: Trophozoite Form

A

6-10 um x 10-20 um
Pear shape, with posterior taper
Single anterior nucleus with small karyosome
Three anterior flagella
Spiral groove
Cytosome with curved “Shepherd’s Crook” fibril
Irregular, jerking movement by anterior flagella

19
Q

Chilomastix mesnili: Cyst Form

A 
6-10 um
Unique lemon shape with anterior polar knob
Thick-walled
Single nucleus
Curved cytosomal fibril
20
Q

Enteromonas hominis: Trophozoite Form

A 
3-6 um x 4-10 um
Oval or Pear shape
Single anterior nucleus with prominent karyosome
Three anterior flagella
One posterior-projecting flagellum
No undulating membrane
Rapid, jerking motion
21
Q

Enteromonas hominis: Cyst Form

A

6-8 um
Oval shape
One to four nuclei seen

22
Q

Pantatrichomonas hominis: Trophozoite Form

A

5-8 um x 10-15 um
Oval or Pear shape
Single anterior nucleus
Four anterior flagella
Undulating membrane with posterior projecting flagellum
Unique costa or thin rod at attachment of body to membrane
Central axostyle with sharply pointed posterior protrusion
Rapid, jerking movement with wavelike motion of undulating membrane

23
Q

Pantatrichomonas hominis: Cyst Form

A

No Cyst Form

24
Q

Retortamonas intestinalis: Trophozoite Form

A 
3-4 um x 4-10 um
Oval or Pear Shape
Single Anterior nucleus with karyosome
Two anterior flagella
Cytosome anteriorly with fibril
Rapid, jerking motion
25
Q

Retortamonas intestinalis: Cyst Form

A

3-5 um x 4-7 um
Pear shape
Single nucleus
Two fibrils seen extending from nucleus to end of cyst, resembling a BIRD’S BEAK

26
Q

Balantidium coli - Balantidiasis (Characteristics)

A
  • Very clinically similar to Entameba histolitica: can stay in the lumen of intestine or invade lumen and cause DYSENTERY*
  • Only infection of man caused by CILIATE
  • Fecal oral transmission, frequently from **PIGS*
  • Generally asymptomatic
27
Q

Balantidium coli - Balantidiasis (Chronic vs Acute Disease)

A

Chronic: Diarrhea Constipation

Acute (Invasion): Diarrhea with BLOOD and MUCUS (similar to amebic dysentery)

28
Q

Cryptosporidium parvum - Cryptosporidiosis (Life Cycle)

A

1) Mature oocyst with sporozoites ingested
2) Sporozoites attach to surface of intestinal epithelium and mature (Schizogony)
3) Sexual forms develop (Gametogony) and produce fertilized oocyst
4) Mature oocyst in feces DIAGNOSTIC STAGE

Know that life cycle is very complicated and there are animal reservoirs (i.e. LIVESTOCK)

29
Q

Cryptosporidium parvum - Cryptosporidiosis (Unique Characteristics)

A
  • Sporozoan parasites have TANK-LIKE TREADS that let it glide
  • Asexual and Sexual reproduction occurs within humans (unlike others, which just have asexual)
  • Oocyst = cyst that has been produced by sexual reproduction
30
Q

Cryptosporidium parvum - Cryptosporidiosis (Disease)

A
  • Not recognized as causing human disease until the 1970s
  • Now known to be a relatively common cause of diarrheal disease
    a) 5000 to 10,000 cases REPORTED annually
  • May be 10x greater than this
    b) Large water-borne outbreaks (Milwaukee)
    c) HIV/AIDS
31
Q

Cryptosporidium parvum - Cryptosporidiosis (Transmission)

A
  • Fecal oral route***
  • Ingestion of infectious oocysts
  • Peaks in early summer to early fall (Community swimming pools?)
32
Q

Cryptosporidium parvum - Cryptosporidiosis (Intestinal Disease)

A
  • PROFUSE WATERY DIARRHEA* accompanied by cramping, fatigue, and weigh loss
  • NO BLOOD*

Generally self-limiting (1-2 weeks) but can be prolonged, severe, and fatal in immunocompromised

33
Q

Cryptosporidium parvum - Cryptosporidiosis (Diagnosis and Control/Prevention)

A

Diagnosis:
-Detection of ACID-FAST OOCYST in stool

Control/Prevention:
-Proper sanitation and water treatment

34
Q

Isospora belli (Life Cycle)

A

1) Ingestion of immature oocyst with sporocyst
2) Sporozoites divide and mature (Schizogony) in cells of intestinal mucosa
3) Sexual replication in the intestines and production of fertilized oocyst
4) Oocyst in feces DIAGNOSTIC STAGE

Elongated oocyst seen in stool sample

35
Q

Isospora belli (Disease)

A
  • Increasingly diagnosed in IMMUNOCOMPROMISED INDIVIDUALS*
  • Fever, diarrhea, weight loss

Sever disease in AIDS patients:

  • Watery diarrhea
  • Malabsorption
  • Weight loss
  • Electrolyte imbalance
  • DEATH
36
Q

Cyclospora (Life Cycle)

A
  • Associated with RASPBERRIES, PRODUCE, WATER*
  • Similar life cycle to Isospora
  • Pink-staining oocysts* in feces

Look like Cryptospiridium

37
Q

Cyclospora (Disease)

A

World-wide distribution
Infected Raspberries

Disease is similar to Cryptosporidiosis:

  • Profuse watery diarrhea
  • Cramping, fatigue, weight loss
  • Prolonged (weeks)

***Disease in AIDS patients is generally more severe and longer in duration

38
Q

Cyclospora (Diagnosis)

A

Oocysts fluorescent under UV light

39
Q

Microsporidia - Microsporidiosis (Characteristics)

A
  • Obligate intracellular parasites (Encephalitozoon, Enterocytozoon, Nosema, and Pleistophora)
  • Primitive eukaryotes
  • World-wide distribution
  • Infection is by INGESTION OF SPORES
  • Organisms may cause intestinal disease or disseminate throughout the body
  • Most of what we know about disease in man is due to the increased occurrence in AIDS patients
  • Common in IMMUNOSUPPRESSED/AIDS/HIV patients*
40
Q

Microsporidia - Microsporidiosis (Intestinal vs Extraintestinal Disease)

A

Intestinal Disease:
-Chronic debilitating diarrhea, anorexia, weight loss (10-20 stools per day)

Extraintestinal Disease:

  • KERATOCONJUNCTIVITIS is frequently seen as an early indicator of dissemination
  • Symptomology is dependent on organ system involved

Microbiology Exam III (9 decks)

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