2 para 3 - amoebas
TRANSCRIPT
-
8/16/2019 2 PARA 3 - Amoebas
1/8oup Jobert | Members: Sayoc, Sebastian, Segovia, Segovia, Serencio Page 1 o
Parasitology 2.3
AMOEBAEDr. Llanera
January 20, 2014
UTLINE
I. Subkingdom Protozoa
a. Class Lobosea
b. Structure
c. Life Cycle
d. Outbreaks
II. Entamoeba histolytica
a. Amoebiasis
b. Amoebic ColitisIII. Entamoeba hartmanii
IV. Entamoeba coli
V. Entamoeba polecki
VI. Endolimax nana
VII. Iodomoeba Butschii
VIII. Dientamoeba fragilis
IX. Entamoeba gingivalis
X. Naegleria fowleri
XI. Acanthamoeba sp.
SUBKINGDOM PROTOZOA
Phylum Sarcomastigophora
-
Subphylum Sarcodina Class Lobosea
-
Subphylum Mastigophora
Class Zoomastigophora
Phylum Ciliophora
- Class Kinetofragminophorea
Phylum Apicomplexa
- Class Sporozoa
CLASS LOBOSEA
Intestinal Species
o Entamoeba histolytica
o Entamoeba hartmanni
o Entamoeba coli
o
Entamoeba poleckio Endolimax nana
o Iodamoeba butschlii
o Dientamoeba fragilis (now under Flagellate family)
o Entamoeba dispar
Other Species
o Entamoeba gingivalis
o Acanthamoeba sp.
o Naegleria fowleri
Entamoeba histolytica name comes from Histo – tissue, lytic
– destroy, meaning tissue destroying. Does not only involve
the invasion of colon but also has extra intestinal
involvement, the only member in its species pathogenic to
man
Entamoeba dispar – morphologcally similar to histolytica but
genetically different because it is non-pathogenic
Entamoeba hartmanni, polecki and nana – smallest ones in
its species, < 7 micra
E. hartmanni also called small race E. histolytica
Entamoeba coli – larger than histolytica
Entamoeba polecki is rarely pathogenic in man, exposure
from pigs and monkeys
Similar to flagellates, it also has developmental stages:
trophozoites and cyst except for Dientamoeba fragilis and
Entamoeba gingivalis, they don’t have cystic stage
STRUCTURE
Pseudopodia - with pseudopods or finger like structures which e
for movement
o Lobose
o Crawling motion (not swimming motion)
o E. histolytica active progressive fast movement
o Entamoeba coli sluggish non progressive movement
Nucleus is compact or vesicular with a dark field structure ca
karyosome (endosome or nucleolus)o In histolytica, the karyosome is smaller and centrally locate
an even peripheral chromatin
o In coli, the karyosome is larger and peripherally located w
irregular peripheral chromatin
o Only genus entamoeba has peripheral chromatin
o Granules inside the periphery of karyosome is fine in E. hist
and coarse in Entamoeba coli
Nucleoplasm
Nuclear membrane
Endoplasm
o With mitochondria
o Food synthesis
o Food vacuoles – stored in chromatoidal bodies;
Chromatoidal bodies in E. histolytica: blunt and round Chromatoidal bodies in Entamoeba coli: sharp, splinter
o Has golgi apparatus, endoplasmic reticulum and microsome
Ectoplasm – clear outer area
o Locomotor apparatus for procurement and ingestion of food
o Discharge of metabolic wastes and protection
Table 1. Entamoeba histolytica VS Entamoeba coli
LIFE CYCLE
Person to person transfer (no cystic stage)
Encystation formation of cyst
o Protective - ciliates
o Reproductive – flagellates & amoebae
Excystation – when cyst becomes trophozites
No intermediate hosts, direct life cycles alternating trophozoite
cyst
Mature cyst is the infective stage, for E. histolytica mature cy
have 4 nuclei and Entamoeba coli would have 8 nuclei
Entamoeba Sp Entamoeba
histolytica
Entamoeba coli
Karyosome Size Smaller Larger
Karyosome Locations Centrally located
Peripherally
located
Peripheral Chromatin Even Uneven
Granules Fine Coarse
Chromatoidal Bodies Blunt and round Sharp, splinter li
Movement Fast, active Slow, sluggish
Trophozoite Content RBC Bacteria, debris
-
8/16/2019 2 PARA 3 - Amoebas
2/8
oup Jobert| Members: Raph, Jobs, Dianelli, Paolo, Kinsley Page 2 o
Parasitology 2.3
Colon would be the initial area of invasion by metacystic trophozoites,
especially the cecum. Because the gastric acidity and chime of intestine
is not conducive for reproductive action so they only become active
once they reach the cecum
They are usually present in the flexures, where the intestines bend like
splenic flexure, hepatic flexure, recto-sigmoid flexure
Trophozoites responsible for extra intestinal manifestations most
common site is the liver, especially the right lobe and then the lungs
Trophozoites (non-infective) and mature cyst (infective) are evacuated
in feces.-
Trophozoites found in liquid, watery stools
- Mature cyst found in formed stools
gure 1. Life Cycle – Mature cyst are ingested. Trophozoites then emerge
om the cyst and invade the colonic wall and reproduce. Mature cyst are
en released in feces
ble 2. Reasons for Amoebic Encystation and Excystation
cystation Excystation
Food supply – high / low
Excess of catabolic products of
the organism or associated
bacteria
pH change (marked)Dessication of medium
O2 supply – high / low
Overpopulation
Osmotic changes in medium
Enzymatic action of the
enclosed organism on the inner
surface of the cyst wall
Among the parasitic protozoa,favorable pH and enzymatic
action of the host tissues
OUTBREAKS
Single or multiple strain
Common in Mental institutions
Polymerase Chain Reaction (PCR) – E. histolytica vs. E. dispar
Laredo strain (Laredo, Texas – F. H. Connell in 1956)
Table 3. Different Spectrums of Amoebic Infection
Classification Characteristics
I.
Asymptomatic Intestinal
Infection
Colonization without
involvement
II. Symptomatic Invasive infection
a. Amoebic dysentery Fulminant ulcerative int
disease
b. Nondysentery colitis Ulcerative intestinal disease
c.
Ameboma Proliferative intestinal granulo
d. Complicated Intestinal
Amebiasis
Perforation, haemorrhage, fist
e. Postamebic colitis Mechanism unknown
III. Extraintestinal Amebiasis
a. Nonspecific hepatomegaly No demonstrable in
accompanies intestinal infectio
b.
Acute Nonspecific
Infection
Amoeba in liver but without ab
c. Amebic Abscess Focal structural lesion
d. Amebic Abscess
Complicated
Direct extension to pleura,
peritoneum, pericardium – if t
pericardial involvement left lo
liver more commonly involvede. Amebiasis cutis Direct extension to skin
f. Visceral amebiasis Metastatic infection of lung,
or brain
ENTAMOEBA HISTOLYTICA
AMOEBIASIS: PATHOGENESIS & PATHOLOGY
Sites of colonization
o Intestinal lesion – Colon (Most specific is in the cecum follow
the rectosigmoid)
High requirement for iron
Primary sites of invasion in colon:
o Early – flask shaped ulcer
o Late – neutrophilic infiltrates
Secondary lesions – other levels of the intestine / extraintestinal
VIRULENCE FACTORS
Susceptibility to agglutination by the lectin concanavalin A
Presence of an adhesion lectin that is inhibited by N-ac
galactosamine
Ability to adhere to epithelial cells in vitro and to initiate cell-co
dependent cytolysis
Ability to phagocytize cells (E. histolytica demonstrate this
ingestion of RBCs – “ erythrophagocytosis” ).
MOBILITY PATTERN BY STARCH GEL ELECTROPHORESIS
Performed on recent parasite isolates grown in the presen
bacteria
Virulent strains of E. histolytica grown in axenic culture (w/o ba
retain their zymodeme pattern (isoenzymes). Zymodeme is imp
as one of the differentiating factor between E. histolytica and E. di
E. dispar was recognized by Brumpt in 1925 as genetically distin
morphologically identical to E. histolytica. With regards
hartmanni, it possesses all the features of E. histolytica but it is s
in size.
1913 – WALKER AND SELLARDS
Human volunteers ingested cysts.
All became infected but only some developed acute dysentery.
As few as 10 cysts have been shown to produce infection.
-
8/16/2019 2 PARA 3 - Amoebas
3/8
oup Jobert| Members: Raph, Jobs, Dianelli, Paolo, Kinsley Page 3 o
Parasitology 2.3
PATHOGENIC ACTIVITIES OF E. HISTOLYTICA DEPEND ON:
Host innate resistance
Virulence and invasiveness of the strain
Conditions of the GI tract
gure 2. Stages and manifestations of Enatamoeba histolytica infection
gure 3. Gross image showing erosion of the intestine with minute
morrhages caused by E. histolytica
gure 4. Histology of the intestine showing flask-shaped ulcer. Amoeba is
ble to penetrate the tunica mucosa by way of the crypts of Lieberkuhn
wards the muscularis mucosa, and the subserosa will be the one to contain
e infection to stop it causing the appearance of a flask-shape ulcer, a
athognomonic histopathologic sign
ote: In organs without submucosa like the gallbladder, when they stretch
e epithelium becomes denuded and disappear in some areas. In effect the
uscle layer increases and leads to deepening of the epithelium forming
kitansky-aschoff sinuses.
SECONDARY LESIONS
Lower colonic segments (rectosigmoid) by regurgitation
Amoebic granuloma (ameboma) in colonic wall – sequel to an am
ulcer
-Remember the oldest/primary lesion is in the cecum, that’s why the
similar to appendicitis.
EXTRAINTESTINAL LESIONS
Liver
Right lobe (Amoebic hepatitis)
o Amoebae caught in the occlusion produce lytic necrosis of th
of the vessels → enter periportal sinusoids and digest patinto the lobules.
o 3 zones (gross / LPO)
Necrotic center filled with thick fluid
Median zone with coarse stroma
Outer zone of nearly normal tissue being invad
amoebae
Figure 5. Aspiration of amoebic abscess aspiration of the liver sh
anchovy-like, dark-brown, or sardines-like aspirate.
If FNAB (Fine Needle Aspiration Biopsy) is done, it is usually CT s
ultrasound guided.
Lungs
Extension of a hepatic abscess by rupture through the diap
(hepatobronchial fistula) – liver-colored sputum
Independent of the liver from the intestine
Pericardial
Left lobe of liver mostly affected
Skin
Amebiasis Cutis
o
Perianal extension of acute amoebic colitiso Abdominal wall through rupture or open drainage of a c
appendiceal, or hepatic lesion
o Penis
o Vulvar amoebiasis is less common.
Brain – Hematogenous / Arises from or concomitant with liver or lungs
Spleen
Adrenals
Renal System – Kidneys, Ureters, Urinary bladders, Urethras
Clitoris
Nasal polyp
Eye
-
8/16/2019 2 PARA 3 - Amoebas
4/8
oup Jobert| Members: Raph, Jobs, Dianelli, Paolo, Kinsley Page 4 o
Parasitology 2.3
AMOEBIC COLITIS: PATHOLOGIC ANATOMY
The earliest, oldest and most advanced erosive ulceration is seen in the
cecal region (cecum, ileocecal valve, appendix, ascending colon)
2nd
in frequency and intensity: sigmoid, rectum
3rd
: splenic and hepatic flexures
SYMPTOMATOLOGY
Incubation period
o Biological incubation: 2 – 5 days or more
o
Clinical incubation: 4 days – 1 yearo Expected incubation: 1 – 4 months
Onset
o Gradual development of symptoms
o Diarrhea, abdominal cramps, or may be asymptomatic
Amoebic Colitis is acute if
-
8/16/2019 2 PARA 3 - Amoebas
5/8
oup Jobert| Members: Raph, Jobs, Dianelli, Paolo, Kinsley Page 5 o
Parasitology 2.3
ANTIAMOEBICS
Metronidazole – kills trophozoites; for E. histolytica, Giardia,
Trichomonas; has metallic taste; do not use with alcohol (disulfiram-like
reactions)
Iodoquinol – luminal amoebicide
Diloxanide Furoate – luminal, if asymptomatic – flatulence, nausea,
rash
Paromomycin Sulfate – luminal
Emetine & Dehydroemetine – toxic
TREATMENT
Metronidazole 750 mg tid x 5-10 days – only used for confirmed cases
of E. histolytica and prophylaxis prior to abdominal surgery
Iodoquinol
Emetine HCl (6% soln) – SQ/IM – 1 mg/kg BW daily x 5 days (max daily
dose of 60 mg) – relieves symptoms > eradicate infection
Dehydroemetine & Emetine – with toxic effects on myocardium &
peripheral nerves
DO NOT give the following: Loperamide HCl, Diphenoxylate HCl,
Thephenamil HCl (may produce toxic megacolon in acute ulcerative
colitis).
ENTAMOEBA HARTMANII
“small race” of E. histolytica
TROPHOZOITES STAGE
Size: 5-12μ
Motility: Usually nonprogressive
Nucleus
o Number: Not visible in unstained preparations
o Peripheral Chromatin: Fine granules; Evenly distributed;
Uniform in size
o Karyosomal Chromatin: Small; Discrete; Eccentrically located
Cytoplasm
o Appearance: Finely granular
o Inclusions: Bacteria
CYSTIC STAGE
Size: 5-10 μ
Shape: Spherical
Nucleus
o Number: 4 in mature cyst; 1-2 in immature cyst
o Peripheral Chromatin: Fine uniform granules; Evenly
distributed
o Karyosomal Chromatin: Small; Discrete; Centrally located
Cytoplasm
o Chromatid Bodies: Elongated bars with bluntly rounded ends
o Glycogen: Diffuse; Stains reddish-brown with iodine
ENTAMOEBA COLI
TROPHOZOITES STAGESize: 15-50 μ
Motility: Sluggish; Non-progressive with blunt pseudopods
Nucleus
o Number: Often visible in unstained preparations
o Peripheral Chromatin: Coarse granules; Irregular in size and
distribution
o Karyosomal Chromatin: Large; Discrete; Eccentrically located
Cytoplasm
o Appearance: Coarse often vacuolated
o Inclusions: Bacteria, Yeasts, etc
Figure 9. Entamoeba coli trophozoite
CYSTIC STAGE
Size: 10-35 μ
Shape: Spherical; Occasionally oval, triangular or another shape
Nucleus
o Number: 8 in mature cyst but there are supernucleate
with 16; 2 in immature cysts
o Peripheral Chromatin: Coarse; Irregularly shaped gra
Irregularly distributed
o Karyosomal Chromatin: Large; Discrete; Usually eccent
located; Occasionally centrally located
Cytoplasm
o
Chromatid Bodies: Less in number than E. histoSplinter-like with pointed ends
o Glycogen: Diffuse; May be a well-defined mass in imm
cysts; Stains reddish-brown with iodine
Figure 10. Entamoeba coli cyst
ENTAMOEBA POLECKI
Usually seen in hogs and monkeys; rarely diagnosed in man
Figure 11. Entamoeba polecki
TROPHOZOITES STAGE
Size: 10-25 μ
Motility: Sluggish; May be progressive in diarrheic stool
Nucleus
o Number: Slightly visible in unstained preparations; M
distorted by pressure from vacuoles in cytoplasm
o Peripheral Chromatin: Fine granules; Evenly distri
Occasionally irregularly arranged; in plaques or crescent
o Karyosomal Chromatin: Small; Discrete; Eccentrically lo
Occasionally large, diffuse or irregular
Cytoplasm
-
8/16/2019 2 PARA 3 - Amoebas
6/8
oup Jobert| Members: Raph, Jobs, Dianelli, Paolo, Kinsley Page 6 o
Parasitology 2.3
o Appearance: Coarse; Granular; Contains numerous vacuoles
o Inclusions: Bacteria; Yeast
CYSTIC STAGE
Size: 9-18 μ
Shape: Spherical or Oval
Nucleus
o Number: 1 to 2
o Peripheral Chromatin: Fine granules evenly distributed
o
Karyosomal Chromatin: Small; Eccentrically locatedCytoplasm
o Chromatid Bodies: Many small bodies with angular or pointed
ends; May be oval or rodlike
o Glycogen: Small diffuse masses; Stains reddish-brown with
iodine; A dark area called Incusion Mass is often present;
Inclusion Mass doesn’t stain with iodine
ENDOLIMAX NANA
“Dwarf Internal Slug”
TROPHOZOITES STAGE
Size: 6-12 μ
Motility: Sluggish; Usually nonprogressive with blunt pseudopods
Nucleus
o Number: Occasionally visible in unstained preparations
o Peripheral Chromatin: None
o Karyosomal Chromatin: Large; Irregularly shaped (blot-like)
Cytoplasm
o Appearance: Granular, vacuolated
o Inclusions: Bacteria
Figure 12. Endolimax nana trophozoite
CYSTIC STAGE
Size: 5-10 μ Shape: Spherical, Ovoid or Ellipsoidal
Nucleus
o Number: 4 in mature cysts; Less than 4 in immature cysts
(rarely seen)
o Peripheral Chromatin: None
o Karyosomal Chromatin: Large; Blot-like; Centrally located
Cytoplasm
o Chromatid Bodies: Granules or small oval masses
o Glycogen: Diffuse; Concentrated mass may be seen in young
cysts; Stains reddish-brown with iodine
Figure 13. Endolimax nana cyst
IODAMOEBA BUTSCHLII
TROPHOZOITES STAGE
Size: 8-20 μ
Motility: Sluggish; Nonprogressive
Nucleus
o Number: Not usually visible in unstained preparations
o Peripheral Chromatin: None
o Karyosomal Chromatin: Large; Centrally located; Surro
by refractive achromatic granules
Cytoplasm
o
Appearance: Coarse, granular, Vacuolatedo Inclusions: Bacteria; Yeasts; Etc.
Figure 14. Iodamoeba butschlii trophozoite
CYSTIC STAGE
Size: 5-20 μ
Shape: Ovoid, Ellipsoidal, Triangular or of another shape
Nucleus
o Number: 1 in mature cyst
o Peripheral Chromatin: None
o Karyosomal Chromatin: Large; Eccentrically located; Ref
achromatic granules on one side; Indistinct in
preparations
Cytoplasm
o Chromatid Bodies: Granular
o Glycogen: Compact well-defined mass; Stains dark
with iodine
Figure 15. Iodamoeba butschlii cyst
DIENTAMOEBA FRAGILIS
Trophozoite only
Non-invasive
-
8/16/2019 2 PARA 3 - Amoebas
7/8
oup Jobert| Members: Raph, Jobs, Dianelli, Paolo, Kinsley Page 7 o
Parasitology 2.3
Size: 6-12 μ
Motility: Single pseudopodia are multiple leaflike hyaline structures;
motion is active and progressive
Nucleus
o Number: Usually 1 but may be 2
o Rosette-shaped nuclei (Belizario)
o Peripheral Chromatin: None
o Karyosomal Chromatin: Fragmented into 4-8 segments
Cytoplasm
o
Appearance: Vacuolatedo Inclusions: Bacteria; Yeast; Starch granules
Figure 16. Dientamoeba fragilis
ENTAMOEBA GINGIVALIS
Trophozoite only
First amoeba to be described
Present only in the mouth
Size: 10-20 μ
Motility: Pseudopodia are usually blunt; moderately active and
progressive motility
Nucleus
o Number: One spheroid nucleus
o Peripheral Chromatin: Fine; Evenly distributed
o Karyosomal Chromatin: Coarse
Cytoplasm
o
Appearance: Vacuolated
o Inclusions: Food, debris, bacteria
Figure 17. E. gingivalis
NAEGLERIA FOWLERI
Free-living amoebo-flagellate
Motile trophozoites
o Amoeboid
o Flagellate (w/ 2 flagella) – shed flagella then resume amoeboid
motility and reproduction
Non motile resistant cysts
Flagellate stage enters nasal cavity; where it reverts to amoeboid form
before invading olfactory tissues and the brain
Cysts instilled intranasally are not infective in experimental animals
PATHOGENESIS, PATHOLOGY & SYMPTOMATOLOGY
Findings:
o Like fulminant bacterial meningitis
o Amoebae in exudates
Primary Amebic Meningoencephalitis
Diagnosis: swimming in thermal/stagnant water 3 to 6 days prio
histopath
Prognosis: fatal within a week
Treatment: none; Amphotericin B and Sulfadiazine
ACANTHAMOEBA
A. culbertsoni
A. polyphaga
A. castellanii
A. stronyxis
ACANTHAMOEBA CULBERTSONI
Amoebic meningoencephalitis, uveitis and ulceration of cornea
Active trophic forms
o No flagellate form
Resistant cysts – resistant to chlorine and can withstand drying
Slow movement of acanthopodia
PATHOGENESIS, PATHOLOGY & SYMPTOMATOLOGY
Purulent leptomeningitis, brain edema, foci of necrosis
Olfactory nerves and lobes not affected
Cerebral hemispheres may be edematous and soft with hemorrh
abscesses. (Belizario)
Most affected areas of the brain: posterior fossa, diencep
thalamus, brainstem
On the affected areas, the leptomeninges are opaque with pu
exudates & vascular congestion. (Belizario)
Figure 18. Pathogenesis of Acanthamoeba. The route of invasion
penetration into the CNS is via the circulatory system, while the prim
sites of infection are either the skin or lungs.
-
8/16/2019 2 PARA 3 - Amoebas
8/8
oup Jobert| Members: Raph, Jobs, Dianelli, Paolo, Kinsley Page 8 o
Parasitology 2.3
Figure 19. Life Cycle of Naegleria fowleri & Acanthamoeba
DIAGNOSIS
Amoebae in CSF, scrapings from lesions in cases of corneal orcutaneous infections; cultures of material from those sources; stained
vaginal smears; purulent discharge from infected ear
TREATMENT
Amphotericin B and sulfadiazine
NAEGLERIA VS ACANTHAMOEBA
APPENDIX
Throphozoites (top) and Cysts (bottom): From left to right: (A) E. histo
(B) E. hartmanii, (C) E. coli, (D) E. polecki, (E) Endolimax nana, (F) Iodam
butschii, (G) Dientamoeba fragilis
REFERENCES
Dr. Llanera’s lecture & ppt
Philippine Textbook of Medical Parasitology (Belizario)
Edited by: Gab Tan
aegleria Acanthamoeba
Pathogenic : 1 species
Olfactory neuroepithelium
Faster course
Pathogenic: 4 species
Broken or ulcerated skin or eye;
lungs or genitourinary tract
Slow tissue invasion
Granuloma formation
Gradual onset; prolonged chronic
course
Chronically ill /
immunosuppressed
MORPHOLOGY Naegleria Acanthamoeba
Trophozoites
Broad pseudopods Filamentous pseudopo
(acanthopodia)
Motility Active Sluggish
Flagellate stage
+
Does not form this stage
Cysts
Thin
walled
Double walled
Pores in cyst wall NoneMay have pores
osteioles
Encystment in
tissue No May encyst in tissue