Blastocystsis Flashcards
Blastocystys hominis
- PROTOZOA
- found worldwide
- affects humans and animals
- most commonly isolated organism in parasite form
- pleomorphic
- 3 major forms
> central body or vacuolated form (clinical specimens such as stools, esp. diarrhea)
> granular and amoeboid form = arise from central body form
- granular = seen mre in cultures; produces 3 types of granules
- amoeba form = seen more in diarrhea; fluid and can be difficult to recogniz
** oxygen exposure to Blastocystis hominis can be very damaging = strict anaerobe **
granular forms of B. hominis
metabolic granules
reproductive granules
lipid granules
old cultures/cultures with serum for B. hominis
granular form
T or F. B. hominis is capable of pseudood extension and retraaction
T!
how does B. hominis reproduce?
by binary fission or sporulation
this takes up 90% of cell and function in sexual and asexual rperoduction
membrane-bound central body
life cycle of B. hominis
can be difficult to undertsand = pleomorphic
- conjugation = transfer of genetic material to the progeny (development in cellular central body) to offspring => release of daughter cells and then
- binary fisson occurs = transverse or longitudinal based on the axis of cell separation
can also be budding, schizogony and sporulation
how does one get infected with B. hominis?
person ingests contam food or water
excystation in large intestine
vacular forms are produced
encystation during passage along large intestine => cyst in feces
transmission of B. hominis
fecal-oral
where does B. hominis reproduction occur?
large intestine
both granular and ameoboid form of B. hominis arise from _____ form
vacoulated or central body form
B. hominis type of reproduction that occurs less commonly in vaculated form
sporulation
what is the function of central body in B. hominis
carbohydrate and lipid storage
central body of B. hominis normally stains __________ with Trichrome
green
but at certain times, central body can also stain red = reason unclear
pathogenesis and symptomatology of B. hominis
- controversial, nonspecific
- genetically diverse group of organisms; mechanism unknown
- clinical pres = diarrhea w/ cramps, bloating, vomiting, fever RARE, or no symptoms at all
- in absence of virus, bacteria, or other parasite, B. hominis may be the cause of (immunocompromised)pt symptoms; B. hominis in feces found in immunocompetent
criteria for B. hominis microscopy
> 5 parasites/hpf
gastrointestinal symptoms
absence of any other co-infecting pathogens and presence of >5 parasites/hpf
epidemiology of B. hominis
higher in developing countries (20-50% tropics)
sources/transmission occurs bc of poor hygiene, consumption of contaminated food and water, exposure to several animals
until more evidence of pathogenicity, significance is no more than any other non-pathogen
Diagnosis of B. hominis
stool mic
cultivation (Jones medium; requires both bacteria nd serum for growth)
T or F. Without signs and symptoms, B. hominis treatment is not required
T!
