Investigation of infection

Question 1

4 aspects to diagnosing infection

Answer 1

History
Clinical Examination
General investigations
Microbiology investigations

Question 2

2 things to consider when ordering tests?

Answer 2

sensitivity and specificity

predictive values

Question 3

4 key things to consider in a history

Answer 3

Symptoms
Travel
Contact with a case
Predisposing/risk factors
-Immunosuppression
-Medical devices (CVC, Implants)
-Exposure to abx

Question 4

3 types of non-microbiological Ix

Answer 4

Bloods – WCC / CRP / PCT
Body fluids – CSF biochemistry
Imaging – X-Ray/USS/CT/MRI

Question 5

4 types of microbiology investigations

Answer 5

Microscopy
Culture (MC&S)
Serological Test (Ag /Ab detection)
Molecular test (Nucleic acid detection)

Question 6

How to decide what test you should order (4)

Answer 6

Depends on…..
Nature of the microbe
Type of host immune response 
Type of sample
Laboratory tests available

Question 7

6 aspects of the chain of investigation

Answer 7

-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

Question 8

3 microbiological tests for Staph aureus

Answer 8

microscopy
NAT (nucleic acid test)
culture

Question 9

3 microbiological tests for Treponema pallidum

Answer 9

microscopy
NAT
Antibody

Question 10

3 microbiological tests for HIV/HBV

Answer 10

antigen
NAT
antibody

Question 11

4 microbiological tests for Cryptococcus

Answer 11

microscopy
antigen
NAT
culture

Question 12

How to diagnose endocarditis?

Answer 12

blood culture
ECHO
Antibody test

Question 13

How to diagnose meningococcal meningitis?

Answer 13

microscopy of CSF
culture
NAT
Antigen 
Antibody detection

Question 14

5 methods of testing for virology?

Answer 14

microscopy
virus isolation (cell culture)
antigen detection 
antibody detection 
nucleic acid detection

Question 15

First line investigations for pyrexia of unknown origin (7)

Answer 15

History
Physical examination
Complete Blood Count
BCs
Routine blood chemistry (LFT  Hepatitis)
Urinalysis
CXR

Question 16

4 categories of pyrexia of unknown origin

Answer 16

• infection e.g. TB, infective endocarditis
• neoplasm e.g. lymphoma
• connective tissue disorders e.g. temporal arteritis sarcoid, SLE
• other e.g. factitious

Question 17

define pyrexia of unknown origin

Answer 17

T>38.3 >3weeks