intestinal and urogenital protozoa

karyosome

nuclear structure

-endosome

-mass of chromatin (dot in center of nucleus)

nuclear DNA

what peripheral chromatin is made of

RNA

what chromatoid is made of

trophozoite (troph)

-motile stage

-feeds, multiplies, maintains colony within host

cyst

-immotile stage

-protected by wall

-ready for transmission to new host

fecal oral (food, water)

cyst transmitted this way with no intermediate host

intestinal tract

where organisms excyst following ingestion

binary fission

how organisms multiply following excystation in intestinal tract

trophs

stage colonizes fecal area following excystation

Entamoeba histolytica

only infection treated

-metronidazole for carriers

-systemic drugs (Iodoquinol, paromomycin) for invasive inf

Entamoeba histolytica

-pathogenic

-asympt colonization (cyst passers)

-amebic dysentry (colitis): flasc shaped ulcers in colon

-extraintestinal amebiasis: liver, lung, pleural absc, peritonitis, skin , genital lesions (anchovy paste pus)

-troph and cyst

Entamoeba histolytica

-troph: 15-25 um, single bulls eye nucleus, may ingest RBCs

-cyst: 10-20 um, 4 nuclei, central cromatoid bar when mature

Entamoeba dispar

-non pathogenic

-troph (15-25): will not ingest RBCs, single bullseye nucleus

-cyst (10-20 um): 4 nuclei, central chromatoid bar

Entamoeba hartmanni

-nonpathogenic

-troph: 4-12 um, small, central karyosome, even peripheral chromatin

-cyst: 5-10 um, small, central karyosome, 1-4 nuclei, cigar-shaped chromatoid bar, evenly distrib chromatin

Entamoeba coli

-nonpathogenic

-troph: 15-50 um, large, eccentric karyosome, uneven chromatin, dirty/vacuolated cyto, engulf bact

-cyst: 10-25 um, 2-8 nuclei, large, eccentric karyosome, splinter-shaped chromatoid bar

Endolimax nana

-nonpathogenic

-troph: 5-12 um, prominent blot like karyosome, no periph chromatin

-cyst: 5-12 um, oval, 4 nuclei, prominent karyosome, granular, vacuolated cyto

Iodamoeba butschlii

-nonpathogenic

-troph: 6-20 um, no periph chromatin, achromatic granules around karyosome, vacuolated cyto

-cyst: 6-15 um, prominent glycogen vacuole, vacuolated cyto, only amebic cyst with one nucleus

Iodamoeba butschlii

cyst form is only cyst with one nucleus

Blastocystis hominis

-mult by binary fission

-3-5 um diameter

-large vacuole surrounded by several small nuclei

-no troph form - only cyst form

Acanthamoeba, Naegleria fowleri

-CNS amoebic pathogens

-directly invading, free-living

-cornea and upper resp tract epithelium

-warm fresh and tap water, heating/air cond units

-humidifiers, dialysis units, eyedrops, contact lens soln

Naegleria fowleri

-pathogenic CNS amoeba

-entry through nose, travels to brain, spinal cord, destroys brain tissue

-swallowing water not a risk factor

-symtoms: PAM and acute primary encephalitis (severe headache, fever, nausea, vom, focal neuro defects, rapid prog to coma, death <10 days)

-diagnostic: trophs in CSF

Naegleria fowleri

-trophs in CSF and brain tissue

-monopodial motion

-can be flagellated

wet prep

most common sample for examination of Naegleria fowleri and Acanthamoeba spp

nature

where Naegleria fowleri cysts are found

Acanthamoeba

-CNS pathogenic amoeba

-cystic keratitis/ulcers: corneal trauma, contacts; encephalitis; granulomatous skin leis

diagnostic:

-motile in CSF

-trichrome of CSF, corneal scraping, skin biopsy

-calcofluor white for cyst

-culture with E. coli overlayed blood agar

Acanthamoeba

-troph: motile (pseudopodia), single nucleus, large central nucleolus (CSF, corneal tissue)

-cyst: “star-like,” nature or body

Balantidium coli (ciliate)

-pathogenic ciliate

-reservoir: swine

-transmission: fecal oral

-ciliated, trophs encyst before or after stool passage

-asympt to invasive (intestinal/extraintestinal)

-diagnostic: stool O&P with trophs and/or cysts with micro and macronucleus (bean shaped), ciliated troph

fecal oral

transmission of pathogenic intestinal flagellates

Giardia lamblia

-pathogenic intestinal flagellate

-asympt carrier

-acute, severe diarrhea with malabsorption, bloating, naus/vom

-inc 5-6 days, 1-3 wk duration

-chronic: same sympt as acute, immunocomp pts

Giardia lamblia

-troph: 9-21 × 5-15 um, pear shaped, flagellated, two nuclei, “face” appearance

-cyst: 8-12 um, oval, 2-4 nuclei, cyto pulls from cell wall, flagella internal

Dientamoeba fragilis

-pathongenic intestinal flagellate

-no cyst form

-troph: 5-12 um, 4-8 clustered granules (nucleus)

-transmitted via pinworm eggs or other pathogens

Trichomonas vaginalis

-pathogenic intestinal flagellate

-urogenital specimens (sometimes stool)

-diagnostic: vaginal wet prep with motile trophs, undulating memb (or EIA)

-no cyst form

-troph: 15-18 um, jerky motility, flagellated, undulating memb

Chilomastix mesnili

-nonpathogenic intestinal flagellate

-troph: 6-24 um, pear-shaped, anterior nucleus with large, eccentric karyosome

-cyst: 6-10 um, lemon shaped, large eccentric nucleus, “fish hook/shepherd’s crook” inclusion

Cryptosporidium parvum

-opportunistic intestinal coccidian

-major cause endemic and epidemic diarrhea

-resistant to chlorination

-ozonation or dessication (2 hr) to kill

-excyst in small intestine epithelial cells, exist outside 

-low infectious dose, persistent watery diarrhea w cramps, weight loss, fever, naus/vom

-diagnostic: oocysts 4-6 um in modified acid fast

-EIA for diarrheal stools

-DFA microsc, PCR

Cyclospora cayetanensis

-opportunistic intestinal coccidian

-tropics/subtropics, contam produce in US (strawbs, rasp from Central America)

-not direct fecal oral → shed oocysts are non-inf for days/weeks

-oocysts on produce ingested and release sporocysts in GI tract and invade mucosal cells

-severe watery diarrhea, anorexia, weight loss, abdom pain, naus/vom, myalgia, low fever, fatigue

-relapses freq

-sample: stool

-diagnostic: oocysts acid fast (variable), 8-10 um, fluor blue in UV

Cyclospora cayetanensis

oocysts 8-10 um, acid fast variable, fluoresce in UV

Cryptosporidium parvum

oocysts 4-6 um, acid fast

Cystoisospora belli

-least common coccidian intestinal pathogen

-tropical/subtropical, US immuncomp and institutional

-invade villous epithelials, sexual and asexual repro

-acute non bloody diarrhea, cramping, abdom pain

-severe in immunosupp infants and children

-eosinophilia

-diagnostic: stool O&P with large, spindle shaped oocysts (20-33 um)

-wet mount, acid fast, fluorescence in calcfluor blue

Cystoisospora belli

oocysts 20-33 um, modified acid fast, fluoresce blue with calcfluor white

-immature: single sporoblast

-mature: two sporoblasts

Cryptosporidium

Cryptosporidium/Cyclospora oocysts are small

Microsporidia

-obligate intracellular parasites

-infectious particle: spore

-highly resistant, long survival

-size varies by species

-polar filament (belt-like stripe) for insertion of genetic material into host

-affects AIDS pts, severe immunocomp

-manifestations dep on species

-chromotrope 2R stain (90 min)

-quick hot gram chromotrope (10 min)

-calcofluor white

chromotrope 2R

stain used for Microsporidia

-pink-red spore wall, visible central belt-like stripe

-90 min

Enterocytozoon bieneusi

-Microsporidia

-spores in stool

-diarrhea

Encephalitozoon intestinalis

-Microsporidia

-spores fluoresce in eye (example)

-diarrhea with dissem to eye, genitourinary, resp tracts