Microbiology-viruses Flashcards
What dose ELISA stand for?
enzyme linked immunosorbent assay
What methods are the old fashioned methods of virus detection?
Electron microscopy
Cytopathic effect
What are the disadvantages of PCR?
So sensitive that it is vulnerable to laboratory contamination
Because you have to use complementary primers, you cannot detect a virus unless you suspect it to begin with- so wouldn’t be able to detect completely new virus
What are the advantages of PCR?
sensitive and quick
What is serology?
The study and detection of antibodies in the serum
Which type of antibody will you find within one week of onset of infection?
IgM
Which type of antibody appears later than IgM but can bind better to the antigen?
igG
What is avidity?
ability to bind to the antigen
Give three examples of techniques used in serology
CFT- complement fixation test
IF- immunoflourescence
ELISA- enzyme linked immunosorbent assay
What kind of swab is done to detect bacteria?
charcoal swab
What kind of swab is done to detect viruses?
green viral swab
What virus causes shingelles?
varicella zoster virus
What colour is a FBC bottle?
purple
What colour is the top of the bottle you would take a sample for serology in?
yellow
What is the medical term for glandular fever?
infectious mononucleosis
What virus causes glandular fever?
Epstein-Barr virus (EBV)
Describe the blood film of a person infected with epstein-Barr virus
Atypical lymphocytes
These vary in form, have basophilic cytoplasm and prominent nucleoli
Describe the ELISA test method
Virus/ bacterial antigen adsorbed to wells of a plate. Unbound antigen is washed away
Patient serum added (usually in two fold dilutions). Plate is washed to remove unbound serum
Anti human IgG or anti human IgM antibodies that are precoupled with an enzyme are added. Plate is washed to remove unbound secondary antibodies
Enzyme substrate added
Colour change indicates positive test
What is the cut off for a significant EBV igM antibody titre in an ELISA test?
1/64
Which antibody type is only detectable in the blood in primary EBV infection?
IgM
Which organ enlarges in glandular fever?
the spleen
What visual symptom can you get with glandular fever?
photophobia
What can happen to the tonsils in a case of glandular fever?
reddening
swelling
white patches
What can happen to the lymph nodes in glandular fever?
swelling
Can you get a cough and a sore throat due to glandular fever?
yes
in what time frame will a blood film come back from the lab?
hours
In what time frame will PCR results come back from the lab?
next day
How long will it take for acute EBV serology to come back from the lab?
1-2 days
Anti-streptolysin O antibodies are produced in response to which exotoxin released by Streptococcus pyogenes ?
streptolysin O
What test would you do to detect anti-streptolysin O antibodies?
latex agglutination test
In a latex agglutination test, what does a positive result look like?
visible agglutination
What advice would you have to give to a rugby player with glandular fever?
avoid playing contact sports for at least 6 weeks to avoid splenic rupture
What drug can you give to patients with flu?
neuraminidase inhibitors
What does qPCR stand for?
quantitative PCR
How does qPCR quantify DNA?
using a flourescent dye that binds to DNA molcules and produces a light signal
What does CMV stand for?
cytomegalovirus
What drug would you give to treat CMV colitis?
ganciclovir
What three different markers in the blood can HIV test look for ?
Antibody, p24 antigen, HIV RNA
In STH what is the first test done for HIV?
Roche COBAS assay
If the Roche COBAS assay test for HIV comes back positive, which tests are then done to confirm the diagnosis?
Liason X and line assay
What do all new positive tests require for confirmation?
A second bleed from the patient
Which test is routinely used for HIV screening in the UK that can simultaneously detect the presence of antigen and antibody and can come back positive often within two weeks of infection?
fourth generation assays
What would you expect CSF protein and glucose to look like in viral meningitis?
normal
What rapid diagnostic test can be done for meningitis?
white cell count
What tests are done on a CSF sample in the lab?
cell count and differential
gram stain for organisms
qPCR for virus and bacterial pathogens
protein and glucose
