Blastocystsis

Question 1

Blastocystys hominis

Answer 1

• 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 **

Question 2

granular forms of B. hominis

Answer 2

metabolic granules
reproductive granules
lipid granules

Question 3

old cultures/cultures with serum for B. hominis

Answer 3

granular form

Question 4

T or F. B. hominis is capable of pseudood extension and retraaction

Answer 4

T!

Question 5

how does B. hominis reproduce?

Answer 5

by binary fission or sporulation

Question 6

this takes up 90% of cell and function in sexual and asexual rperoduction

Answer 6

membrane-bound central body

Question 7

life cycle of B. hominis

Answer 7

can be difficult to undertsand = pleomorphic

1. conjugation = transfer of genetic material to the progeny (development in cellular central body) to offspring => release of daughter cells and then
2. binary fisson occurs = transverse or longitudinal based on the axis of cell separation

can also be budding, schizogony and sporulation

Question 8

how does one get infected with B. hominis?

Answer 8

person ingests contam food or water

excystation in large intestine

vacular forms are produced

encystation during passage along large intestine => cyst in feces

Question 9

transmission of B. hominis

Answer 9

fecal-oral

Question 10

where does B. hominis reproduction occur?

Answer 10

large intestine

Question 11

both granular and ameoboid form of B. hominis arise from _____ form

Answer 11

vacoulated or central body form

Question 12

B. hominis type of reproduction that occurs less commonly in vaculated form

Answer 12

sporulation

Question 13

what is the function of central body in B. hominis

Answer 13

carbohydrate and lipid storage

Question 14

central body of B. hominis normally stains __________ with Trichrome

Answer 14

green
but at certain times, central body can also stain red = reason unclear

Question 15

pathogenesis and symptomatology of B. hominis

Answer 15

• 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

Question 16

criteria for B. hominis microscopy

Answer 16

> 5 parasites/hpf
gastrointestinal symptoms

absence of any other co-infecting pathogens and presence of >5 parasites/hpf

Question 17

epidemiology of B. hominis

Answer 17

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

Question 18

Diagnosis of B. hominis

Answer 18

stool mic
cultivation (Jones medium; requires both bacteria nd serum for growth)

Question 19

T or F. Without signs and symptoms, B. hominis treatment is not required

Answer 19

T!