Investigation of infection Flashcards
4 aspects to diagnosing infection
History
Clinical Examination
General investigations
Microbiology investigations
2 things to consider when ordering tests?
sensitivity and specificity
predictive values
4 key things to consider in a history
Symptoms Travel Contact with a case Predisposing/risk factors -Immunosuppression -Medical devices (CVC, Implants) -Exposure to abx
3 types of non-microbiological Ix
Bloods – WCC / CRP / PCT
Body fluids – CSF biochemistry
Imaging – X-Ray/USS/CT/MRI
4 types of microbiology investigations
Microscopy
Culture (MC&S)
Serological Test (Ag /Ab detection)
Molecular test (Nucleic acid detection)
How to decide what test you should order (4)
Depends on….. Nature of the microbe Type of host immune response Type of sample Laboratory tests available
6 aspects of the chain of investigation
-Which specimens, whether, when, how? Lab users’ guide – test only with consent
-Transport to lab
Urgent? Point of Care Testing?
-Analysis in the lab
-Reporting from lab -Telephone + electronic
-Guidance for the clinician and patient
Electronic and in person
-If you send the test – you must check the result
3 microbiological tests for Staph aureus
microscopy
NAT (nucleic acid test)
culture
3 microbiological tests for Treponema pallidum
microscopy
NAT
Antibody
3 microbiological tests for HIV/HBV
antigen
NAT
antibody
4 microbiological tests for Cryptococcus
microscopy
antigen
NAT
culture
How to diagnose endocarditis?
blood culture
ECHO
Antibody test
How to diagnose meningococcal meningitis?
microscopy of CSF culture NAT Antigen Antibody detection
5 methods of testing for virology?
microscopy virus isolation (cell culture) antigen detection antibody detection nucleic acid detection
First line investigations for pyrexia of unknown origin (7)
History Physical examination Complete Blood Count BCs Routine blood chemistry (LFT Hepatitis) Urinalysis CXR
