Investigations Flashcards
When would you carry out a microbiological smear?
for testing for the presence of fungi or bacteria
What microbiological investigations are there?
Smear
Plain Swab
Imprint culturte
Oral rinse
When would you use a plain swab?
To detect for fungi, bacteria, HSV and VZV
When would you carry out an imprint culture?
to determine bacteriological or fungal coloinisation of mucosa or surface of an IO appliance
Foam swab placed on site and sent to lab
What do you use in a concentrated oral rinse?
10ml buffered phosphate saline
How should tissue biopsied for immunofluorescence be sent to the lab?
should be sent on fresh ice or in michels solution
what is vital staining?
Use of toluidine blue stain which is picked up by areas of abnormal mucosa, however some normal mucosa is also picked up. Used only as an adjcunt
How do you perform the schirmer test?
This tests investigates lacrimal fluid flow
Placing a filter paper under the eyelid for 5 minutes.
Wetting of the paper of less than 5mm indicates reduced tear production
when do you perform the schilling test?
to investigate B12 deficiency
looks at the amount of B12 excreted in the urine
what is the purpose of a biopsy?
removal/sample of tissue for histopath assessment
What colours are H and E staining?
Eosin stains pink
Haem: stains blue
what structures does eosin stain?
keratin
muscle
Bone (un Ca)
collagen
What structures does Haematoxylin stain?
Nuclei
cytoplasm
ground substance
Un Ca bone
when do you use the PAS stain?
periodic acidic schiff stain
Fungi/mucins/glycogen
when is the ziehl neelsen stain used?
Mycobacteria
when is the congo red stain used?
amyloid protein
what does immunohistochemistry look at? at when is it used?
monoclonal antibodies to antigens on cell surface. used to detect where primary site of tumour is
what type of tissue preparation is needed for immunohistochem?
frozen or fixed
what is the issue with frozen section tissues?
poor quality tissue
when would you use frozen tissue?
when need rapid assessment of tissues
What is the Paul bunnel test used for?
For diagnosis of IM via Detection of EBV
What is used in the Paul bunnel test?
Patients serum is used to see if it causes agglutination of sheep erythrocytes. If EBV is present then the sheep erythrocytes will agglutinate
What test has superseded the Paul bunnel test?
The mono spot test
How does the mono spot test work?
It tests the patients serum for presence of heterophile antibodies by mixing horse red blood cells and the serum.
If EBV/CMV is present then the horse erythrocytes will agglutinate
What other lab test can be used in IM?
Presence of atypical lymphocytes on blood smear
What does heterophile antibodies mean in terms of lab testing?
They can cross react with antigens across species lines
What is the problem with using the monospt test?
It is more of a screening method since the test may come back negative if in the first week of IM. So negative results should be repeated after a few days. Also in children aged less then 8 am EBV serology test should be performed if EBV is suspected
When is the gram stain used?
Bacteria and some fungi
What machine is used to free the tissues for frozen section?
Cryostat
