Making an Infection Diagnosis

Question 1

What does microbiology do?

Answer 1

Diagnostic advice, treatment advice and infection control

Question 2

Describe the role on an infection specialist

Answer 2

Provide diagnostic tests, clinical consultation service for patents with suspected infection, clinical advice on interpreting results, provide advice on therapy of serious infections and manage control of infection issues.

Question 3

How do microbiologists make diagnosis

Answer 3

By;

direct examination, cultures, serology and molecular

Question 4

Name some of the tests that microbiologists use to diagnose?

Answer 4

Smear diagnosis - rapid, cheap and simple however not very specific or sensitive (examples include using light/fluorescent/electron microscopy)
Culture diagnosis - More sensitive than smear, allows detailed identification and susceptibility testing but is rendered negative by antibiotics.
MALDI-TOF - rapid identification, but does not provide susceptibilities and antibiotics render cultures negative.

Question 5

Describe what serology diagnosis can do

Answer 5

Detect high IgG concs, the rising of falling titres, detect IgM/IgA and antigens and can measure avidity (strength) of binding - examples are immunofluorescence and ELISA

Question 6

Give two examples of molecular techniques

Answer 6

DNA hybridisation and nucleic acid amplification testing

Question 7

Give some examples of specimens that are taken for certain diseases

Answer 7

UTI - midstream trine collection
Wound - pus or swab
Meningitis - CSF and blood
Pyrexia (fever) of unknown origin - blood for culture and serology
Pneumonia - Sputum, lavage and serology

Question 8

What is sensitivity?

Answer 8

The ability of a test to detect all of the true positives.

Question 9

What is specificity

Answer 9

Ability to identify the number of true negatives.