making an infection diagnosis Flashcards
what 3 things does microbiology do?
1) Diagnostic advice – identifying the infecting organism
2) Treatment advice – Susceptibility test (what antibiotics may be effective)
3) Infection control – Identify clustered organisms over-represented in the community
why do clinicians not use microbiology results?
the spread of progression of infection than the time taken to generate the results
what is the role of microbiologist?
1) Provide high quality diagnostic tests
2) Provide a clinical consultation service for patients with suspected infection
3) Provide clinical advice on the interpretation of diagnostic tests
4) Provide advice on therapy of serious infections
5) Manage control of infection issues within the hospital environment
what are 4 ways to make a microbiological diagnosis?
- direct exam
- serology
- culture
- molecular
describe smear diagnosis as a type of direct examination
- fast and simple
- cheap
BUT - not very sensitive
- not very specific
- requires considerable expertise to actually do it.
describe microscopy as a direct examination method?
you can use light, flourescent or electron microscopy all used to detect different things.
what is maldi-tof? and what are its advantages and disadvantages?
it is a mass spectometer (type of culture diagnosis)
ADVANTAGES
- rapid identification of bacteria
DISADVANTAGES
- does not provide susceptabilities
- delayed by slow growth
- it is of no value if the antibiotics render the culture negative.
what are the advantages and disadvantages of culture diagnosis?
ADVANTAGES
- more sensitive than a smear test
- allows suceptability testing
- allows a rapid persumptive diagnosis
- allows detailed identification
DISADVANTAGE
- rendered negative by antibiotics
what does serology tests look for?
- high IgG conc
- rising of falling titres
- detect IgM/IgA
- measure avidity of binding
- detects antigens
a rise or fall in any of these will give ou an insight into what is casuing the infection.
what is serology?
this is the scientific study of diagnostic examination of blood serum
eg- agglutination
what are 2 examples of molecular diagnosis?
- DNA hybridisation
- nucleic acid amplification testing (eg - PCR)
if someone has meningitis, what type of sample would you take?
CSF and blood
what is wrong with culture based diagnosis?
- slow
- many organisms do not grow on agar
- specimens will be rendered negative by antibiotics
- missing prognostic info
- aetiology not understood
definition of…
- culture
- viable
- viable culture
culture = they will grow on agar
viable = they will not grow on agar
viable culture = alive and will grow on agar
what is an example of a speciman with a single pathogen?
- throat swab
