5. Amoeba

Question 1

“false feet”

Answer 1

Pseudopods

Question 2

Two morphological forms

Answer 2

Trophozoites and cysts

Question 3

Mode of transmission

Answer 3

Ingestion of infective cyst

Question 4

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

Answer 4

Excystation

Question 5

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

Answer 5

Encystation

Question 6

Factors contributing to encystation:

Answer 6

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

Question 7

E. histolytica

Answer 7

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

Question 8

E. histolytica

Answer 8

MATURE CYST –infective ; quadrinucleated ; fine granular cytoplasm

Question 9

E. histolytica YOUNG

Answer 9

• 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

Question 10

the only known pathogenic intestinal ameba

Answer 10

E. histolytica

Question 11

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

Answer 11

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

Question 12

Symptomatic intestinal Amebiasis

Answer 12

• Amebic dysentery
• Amebic colitis

Question 13

• FLASK-SHAPED amebic ulcer
• PRIMARY ULCER , PERITONITIS

Answer 13

E. histolytica

Question 14

SYMPTOMATICEXTRAINTESTINAL AMEBIASIS

Answer 14

• AMEBIC PNEUMONITIS
• VENEREALAMEBIASIS
• PENILE AMEBIASIS /VAGINAL AMEBIASIS

Question 15

Laboratory diagnosis of e. histolytica

Answer 15

• 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

Question 16

E. histolytica MOT and Vectors

Answer 16

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

Question 17

Once designated as “SMALL RACE”

Answer 17

E. hartmanni

Question 18

E. hartmanni Trophozoite:

Answer 18

• FINGER SHAPED pseudopods exhibiting NONPROGRESSIVE motility
• Contain ONENUCLEUS

Question 19

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

Answer 19

E. hartmanni

Question 20

E. coli TROPHOZOITES

Answer 20

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

Question 21

E. coli treatment

Answer 21

• Asymptomatic
• Treatment Is Not Indicated

Question 22

E. coli CYSTS

Answer 22

• 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

Question 23

E. polecki TROPHOZOITES

Answer 23

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

Question 24

E. polecki CYSTS

Answer 24

• Spherical to oval in shape
• Contains only ONE NUCLEUS

Question 25

* Considered primarily a parasite of the pigs and monkeys * Human infection is relatively rare * Highest prevalence in Papua, New Guinea

Answer 25

E. polecki

Question 26

E. polecki TROPHOZOITES

Answer 26

* MOTILITY: sluggish, nonprogressive motility * BLUNT, HYALINE PSEUDOPODS * single nucleus * KARYOSOME: “BLOTLIKE” in appearance

Question 27

Key feature of e. polecki

Answer 27

ABSENCE OF PERIPHERAL CHROMATIN

Question 28

e. polecki cysts

Answer 28

* 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

Question 29

I. butschlii trphozoites

Answer 29

* 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

Question 30

I. butschlii

Answer 30

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

Question 31

I. butschlii lab diagnosis

Answer 31

* 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

Question 32

E. gingivalis trphozoites

Answer 32

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

Question 33

causes “Primary Amebic Meningoencephalitis (PAM)”

Answer 33

Naegleria fowleri

Question 34

THREE KNOWN PATHOLOGIC FORMS OF N. fowleri:

Answer 34

1. Cyst 2. Ameboid Trophozoites 3. FLAGELLATE Forms

Question 35

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

Answer 35

PRIMARY AMEBIC MENINGOENCEPHALITIS (PAM)

Question 36

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

Answer 36

Kernig’s sign

Question 37

N. fowleri treatment

Answer 37

* Prompt and aggressive treatment with AMPHOTERICIN B * Amphotericin B in combination with RIFAMPIN or MICONAZOLE * Amphotericin B and Miconazole * RIFAMPIN – inhibits RNA synthesis

Question 38

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

Answer 38

Acanthamoeba spp.

Question 39

N. fowleri lab diagnosis

Answer 39

* 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