Intestinal protozoa: Difference between revisions

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= Microbiology =
==Microbiology==


* Protozoans are eukaryotic unicellular organisms that have organelles
*Protozoans are eukaryotic unicellular organisms that have organelles
* Many have a '''trophozoite''' form (active, motile), as well as a '''cyst''' form (vegetative)
*Many have a '''trophozoite''' form (active, motile, feeding form), as well as a '''cyst''' form (vegetative, difficult-to-kill)
* Stains:
*Stains:
** Iron hematoxilin, which stains nuclei on a black background
**Iron hematoxilin, which stains nuclei on a black background
** Acid-fast stain, which highlights red Crypto/Cyclo/Iso
**Acid-fast stain, which highlights red [[Cryptosporidium species|Cryptosporidium]]/[[Cyclospora cayetanensis|Cyclospora]]/[[Cystoisospora belli|Cystoisospora]]
** Can combine both of the above
**Can combine both of the above


= Classification =
==Classification==


From largest to smallest family
From largest to smallest family


* Amoebae
*Amoebae
** ''Entamoeba histolytica/dispar'' (microscopically indistinguishable, but ''E. dispar'' is non-pathogenic)
**''[[Entamoeba histolytica]]/dispar'' (microscopically indistinguishable, but ''E. dispar'' is non-pathogenic)
** ''E. harmanni'' and ''E. coli'' (non-pathogenic)
**''Entamoeba harmanni'' and ''Entamoeba coli'' (non-pathogenic)
** ''Endolimax nana''
**''[[Endolimax nana]]''
** ''Iodamoeba butchlii''
**''[[Iodamoeba butchlii]]''
* Flagellates
*Flagellates
** ''Giardia lamblia''
**''[[Giardia lamblia]]''
** ''Dientamoeba fragilis'' (no cystic form)
**''[[Dientamoeba fragilis]]'' (no cystic form)
** ''Chilomastix mesnili''
**''[[Chilomastix mesnili]]''
* Ciliates
*Ciliates
** ''Balantidium coli''
**''[[Balantidium coli]]''
* Coccidia: small, may be seen as acid-fast
*Coccidia: small, may be seen as acid-fast
** ''Cryptosporidium''
**[[Cryptosporidium]] (~5 μm)
**[[Cyclospora cayetanensis|Cyclospora cayetanensis (~10 μ]]<nowiki/>m)
** ''Cyclospora''
** ''Cystoisospora'' (previously ''Isospora'')
**[[Cystoisospora belli]] (previously called ''Isospora'') (~30 μm)
** ''Sarcocystis hominis''
**[[Sarcocystis hominis]]
* Microsporidia
*[[Microsporidia]]


==Identification==
= Approach to Microscopy =


* Some have classic appearance:
*Some have classic appearance:
** ''Giardia'' trophs look like an owl
**''[[Giardia]]'' trophs look like an owl
* ''Balantidium coli'' is huge
**''[[Balantidium coli]]'' is huge
** ''Trichomonas'' and ''Chilomastix'' trophs have flagellae and are tear-drop shaped
**''[[Trichomonas]]'' and ''[[Chilomastix]]'' trophs have flagellae and are tear-drop shaped
* ''Isospora belli'' looks like an eye or halved egg
**''[[Cystoisospora belli]]'' looks like an eye or halved egg
** ''Cyclospora'' is thick-walled and looks like a golf ball
**''[[Cyclospora]]'' is thick-walled and looks like a golf ball
* ''Cryptosporidium'' is the smallest (4-6 µm) and may have crescent-shaped sporozoites inside
**''[[Cryptosporidium]]'' is the smallest (4-6 µm) and may have crescent-shaped sporozoites inside
** ''Sarcocystis'' is quite large (15 µm), non-acid-fast, and looks like 2 joined ovals
**''[[Sarcocystis]]'' is quite large (15 µm), non-acid-fast, and looks like 2 joined ovals

⚫
* In order to differentiate the larger Amoebae, need to consider the size, nucleus characteristics, and other features
=== Amoebae ===
⚫
* What kind of nucleus is it?

⚫
** Entamoeba: dark ing of peripheral chromatin, with a defined central nucleus and relatively clear perikarysomal space
⚫
*In order to differentiate the larger Amoebae, need to consider the size, nucleus characteristics, and other features
⚫
** Non-entamoeba: more blob-like, less well defined
**Does is stain acid-fast? If yes, it is one of the "sporas"
⚫
** Granulated: big dots, suggests ''Dientamoeba fragilis'' trophozoite
⚫
**What kind of nucleus is it?
⚫
* How many nuclei?
⚫
***''Entamoeba'': dark ring of peripheral chromatin, with a defined central nucleus and relatively clear perikarysomal space
⚫
** Trophs are mostly mono-nucleated, cysts may be poly-nucleated
⚫
***Non-''Entamoeba'': more blob-like, less well defined
⚫
** ''Dientamoeba'' has 2 nuclei in troph form
⚫
***Granulated: big dots, suggests ''[[Dientamoeba fragilis]]'' trophozoite
⚫
* What is the average size?
⚫
**How many nuclei?
⚫
** Need a measurement microscope
⚫
***Trophozoites are mostly mono-nucleated, cysts may be polynucleated
⚫
* Other stuff
⚫
***''[[Dientamoeba]]'' has 2 nuclei in trophozoite form
⚫
** Large vacuole suggests ''Iodamoeba butschlii''
⚫
**What is the average size?
⚫
** Uneven chromatin suggests ''E. coli''
⚫
***Need a measurement microscope
⚫
** Chromatoidal bars suggests ''E. polecki'', ''E. histolytica'', or ''E. hartmanni''
⚫
*Other stuff
⚫
**Large vacuole suggests ''[[Iodamoeba butschlii]]''
⚫
**Uneven chromatin suggests ''[[Entamoeba coli]]''
⚫
**Chromatoidal bars suggests ''[[Entamoeba polecki]]'', [[Entamoeba histolytica|''Entamoeba'' ''histolytica'']], or [[Entamoeba hartmanni|''Entamoeba'' ''hartmanni'']]


{| class="wikitable"
{| class="wikitable"
! Organism
!Organism
! Nucleus type
!Nucleus type
! No. nuclei
!No. nuclei
! Size
!Size
! Other features
!Other features
|-
|-
| ''E. histolytica''
|''[[E. histolytica]]''
| Entamoeba type
|Entamoeba type
| 2-4
|2-4
| &gt; 10 µm
|&gt; 10 µm
| Chromatoidal bars
|Chromatoidal bars
|-
|-
| ''E. coli''
|''[[Entamoeba coli|E. coli]]''
| Entamoeba type
|Entamoeba type
| 5-8+
|5-8+
| &gt; 10 µm
|&gt; 10 µm
|
|
|-
|-
| ''E. hartmanni''
|''[[Entamoeba hartmanni|E. hartmanni]]''
| Entamoeba type
|Entamoeba type
|
|
| &lt; 10 µm
|&lt; 10 µm
| Chromatoidal bars
|Chromatoidal bars
|-
|-
| ''E. polecki''
|''[[Entamoeba polecki|E. polecki]]''
| Entamoeba type but 1/3 cell width
|Entamoeba type but 1/3 cell width
|
|
| &gt; 10 µm
|&gt; 10 µm
| Chromatoidal bars, but may have glycogen mass
|Chromatoidal bars, but may have glycogen mass
|-
|-
| ''Iodamoeba''
|''[[Iodamoeba butschlii|Iodamoeba]]''
| Blob-like
|Blob-like
| 1
|1
|
|
| Large vacuole
|Large vacuole
|-
|-
| ''Endolimax''
|''[[Endolimax]]''
| Blob-like
|Blob-like
| 2-4
|2-4
|
|
|
|
|}
|}


=== Coccidia ===

* No serology available
* Culture difficult or impossible
* May be seen on histopathology of biopsy specimens

{| class="wikitable"
!Organism
!Size of oocyst
!Stool O&P
!Stool antigen
!Acid-fast
!Other stain
|-
|[[Cryptosporidium]]
|4-6 μm
| +
| +
| +
|immunofluorescence
|-
|[[Cyclospora cayetanensis]]
|8-10 μm
| +
|–
| +
|
|-
|[[Cystoisospora belli]]
|23-33 x 10-19 μm
| +
|–
| +
|
|-
|[[Microsporidia]]
|1-3.5 μm
|±
|–
|–
|chromotrope, calcofluor
|}
[[Category:Microbiology]]
[[Category:Microbiology]]
[[Category:Parasites]]
[[Category:Protozoa]]

Latest revision as of 02:47, 8 February 2022

Microbiology

  • Protozoans are eukaryotic unicellular organisms that have organelles
  • Many have a trophozoite form (active, motile, feeding form), as well as a cyst form (vegetative, difficult-to-kill)
  • Stains:

Classification

From largest to smallest family

Identification

Amoebae

  • In order to differentiate the larger Amoebae, need to consider the size, nucleus characteristics, and other features
    • Does is stain acid-fast? If yes, it is one of the "sporas"
    • What kind of nucleus is it?
      • Entamoeba: dark ring of peripheral chromatin, with a defined central nucleus and relatively clear perikarysomal space
      • Non-Entamoeba: more blob-like, less well defined
      • Granulated: big dots, suggests Dientamoeba fragilis trophozoite
    • How many nuclei?
      • Trophozoites are mostly mono-nucleated, cysts may be polynucleated
      • Dientamoeba has 2 nuclei in trophozoite form
    • What is the average size?
      • Need a measurement microscope
  • Other stuff
Organism Nucleus type No. nuclei Size Other features
E. histolytica Entamoeba type 2-4 > 10 µm Chromatoidal bars
E. coli Entamoeba type 5-8+ > 10 µm
E. hartmanni Entamoeba type < 10 µm Chromatoidal bars
E. polecki Entamoeba type but 1/3 cell width > 10 µm Chromatoidal bars, but may have glycogen mass
Iodamoeba Blob-like 1 Large vacuole
Endolimax Blob-like 2-4

Coccidia

  • No serology available
  • Culture difficult or impossible
  • May be seen on histopathology of biopsy specimens
Organism Size of oocyst Stool O&P Stool antigen Acid-fast Other stain
Cryptosporidium 4-6 μm + + + immunofluorescence
Cyclospora cayetanensis 8-10 μm + – +
Cystoisospora belli 23-33 x 10-19 μm + – +
Microsporidia 1-3.5 μm ± – – chromotrope, calcofluor
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