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Parasitology > 5. Amoeba > Flashcards

5. Amoeba Flashcards

1
Q

“false feet”

A

Pseudopods

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2
Q

Two morphological forms

A

Trophozoites and cysts

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3
Q

Mode of transmission

A

Ingestion of infective cyst

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4
Q

the morphologic conversion from the cyst form into the trophozoite form; occurs in the ileocecal area of the intestine

A

Excystation

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5
Q

conversion of trophozoites to cysts; occurs in the intestine when the environment becomes unacceptable for continued trophozoite multiplication

A

Encystation

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6
Q

Factors contributing to encystation:

A
  1. Ameba overpopulation
  2. pH change
  3. Food supply
  4. Oxygen supply
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7
Q

E. histolytica

A

Trphozoite:
• MOVEMENT: RAPID, UNIDIRECTIONAL, PROGRESSIVE
• Finger-like hyaline pseudopods

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8
Q

E. histolytica

A

MATURE CYST –infective ; quadrinucleated ; fine granular cytoplasm

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9
Q

E. histolytica YOUNG

A

• CHROMATOID BARS –from unorganized chromatin materials; SQUARED AND ROUND-ENDED STRUCTURES THAT CONTAIN RNA
• GLYCOGEN MASS – without defined borders ; stored food ; disappears when the cyst matures

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10
Q

the only known pathogenic intestinal ameba

A

E. histolytica

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11
Q

(E. histolytica)
ASYMPTOMATIC CARRIER STATE:
• Three factors:

A

1.LOW-VIRULENCE STRAIN
2. The INOCULATION into the host is LOW
3. The patient’s immune system is INTACT

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12
Q

Symptomatic intestinal Amebiasis

A

• Amebic dysentery
• Amebic colitis

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13
Q

• FLASK-SHAPED amebic ulcer
• PRIMARY ULCER , PERITONITIS

A

E. histolytica

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14
Q

SYMPTOMATICEXTRAINTESTINAL AMEBIASIS

A

• AMEBIC PNEUMONITIS
• VENEREALAMEBIASIS
• PENILE AMEBIASIS /VAGINAL AMEBIASIS

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15
Q

Laboratory diagnosis of e. histolytica

A

• STOOLEXAM
• SAMPLESFROMSIGMOIDOSCOPYandHEPATICABSCESS
• TYI-S-33
• Antigen test, ELISA, (IHA), (GDP),(IIF)
• Serologic tests- useful in extraintestinal infections.
• Distinguishing invasive and noninvasive strains : isoenzyme electrophoresis and examining the zymodemes

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16
Q

E. histolytica MOT and Vectors

A

• MOT: Ingestion of infective stage, unprotected sexual contact
• VECTORS: Flies and cockroaches

17
Q

Once designated as “SMALL RACE”

A

E. hartmanni

18
Q

E. hartmanni Trophozoite:

A

• FINGER SHAPED pseudopods exhibiting NONPROGRESSIVE motility
• Contain ONENUCLEUS

19
Q

peripheral chromatin PRESENT as evenly distributed granules, “Beaded appearance”

A

E. hartmanni

20
Q

E. coli TROPHOZOITES

A

TROPHOZOITES
• BLUNT PSEUDOPODS which exhibits SLUGGISH, NONPROGRESSIVE MOTILITY • SINGLE NUCLEUS with a LARGE, IRREGULARYSHAPED, ECCENTRIC karyosome which is surrounded by DISTRIBUTED peripheral chromatin UNEVENLY
• KARYOSOME and PERIPHERAL CHROMATIN appear as REFRACTILE STRUCTURES in unstained preparation

21
Q

E. coli treatment

A
  • Asymptomatic
  • Treatment Is Not Indicated
22
Q

E. coli CYSTS

A

• THICK WALL surrounds the round to spherical cyst
• Cyst nuclei are readily discernible • One to eight nuclei
• Occasionally, large cyst contain 16 or more nuclei

23
Q

E. polecki TROPHOZOITES

A

TROPHOZOITES
* MOTILITY: Sluggish, non-progressive motility in
normal consistency of the stool ; progressive,
unidirectional motility in diarrheal stools
* KARYOSOME: resemble that of E.histolytica
* PERIPHERAL CHROMATIN: resemble that of
E.coli

24
Q

E. polecki CYSTS

A
  • Spherical to oval in shape
  • Contains only ONE NUCLEUS
25
Q
  • Considered primarily a parasite of the pigs and monkeys
  • Human infection is relatively rare
  • Highest prevalence in Papua, New Guinea
A

E. polecki

26
Q

E. polecki TROPHOZOITES

A
  • MOTILITY: sluggish, nonprogressive motility
  • BLUNT, HYALINE PSEUDOPODS
  • single nucleus
  • KARYOSOME: “BLOTLIKE” in appearance
27
Q

Key feature of e. polecki

A

ABSENCE OF PERIPHERAL
CHROMATIN

28
Q

e. polecki cysts

A
  • SPHERICAL,OVOID, or ELLIPSOIDAL
  • Most commonly seen mature cyst contains FOUR
    nuclie
  • Large “blot-like” karyosome which is usually
    centrally located, absence of peripheral chromatin
29
Q

I. butschlii trphozoites

A
  • PROGRESSIVE,SLUGGISH motility
  • NUCLEUS: large, central karyosome
    surrounded by refractive achromatic
    granules
  • PERIPHERAL CHROMATIN:
    ABSENT
  • Coarsely granular and vacuolated cytoplasm may contain bacteria, yeast
    cells, and other debris
30
Q

I. butschlii

A
  • Resembles “basket of flowers” in
    shape
  • SIZE: 8 – 12 um
  • Shape may vary (ovoid, ellipsoidal,
    triangular)
  • Contain one nucleus
  • Large karyosome is eccentrically
    located
31
Q

I. butschlii lab diagnosis

A
  • Stool Exam
  • Iodine Wet Preparations (Cyst)
  • Glycogen Mass: takes up the iodine stain ;
    remains unstained in trichrome staining
  • Unstained in Trichome stain: another feature
    that aids in identification of I.butschilii
32
Q

E. gingivalis trphozoites

A
  • Exibits ACTIVE MOTILITY (multiple
    pseudopods)
  • Inclusions: food vacuoles containing
    phagocytosed and partially digested
    WBCs; epithelial cells; ingested RBCs
33
Q

causes “Primary Amebic Meningoencephalitis (PAM)”

A

Naegleria fowleri

34
Q

THREE KNOWN PATHOLOGIC
FORMS OF N. fowleri:

A
  1. Cyst
  2. Ameboid Trophozoites
  3. FLAGELLATE Forms
35
Q

Occurs when the ameboid trophozoites invade the brain,
causing rapid tissue destruction

A

PRIMARY AMEBIC MENINGOENCEPHALITIS (PAM)

36
Q

The appearance of resistance or pain during extension of the patient’s knees beyond 135 degrees

A

Kernig’s sign

37
Q

N. fowleri treatment

A
  • Prompt and aggressive treatment with AMPHOTERICIN B
  • Amphotericin B in combination with RIFAMPIN or
    MICONAZOLE
  • Amphotericin B and Miconazole
  • RIFAMPIN – inhibits RNA synthesis
38
Q

causes “granulomatous amebic encephalitis (gae), acanthamoeba keratitis”

A

Acanthamoeba spp.

39
Q

N. fowleri lab diagnosis

A
  • SPECIMEN of CHOICE: CSF
  • Brain tissue, corneal scrapings
  • Culture on non-nutrient agar with gram-negative bacteria
  • Histologic examination
  • Calcoflour white
  • Technique of choice: Indirect immmunoflourescent antibody
    staining

Parasitology (6 decks)

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