diagnosis and sampling

Question 1

sterile and non sterile sites?

Answer 1

Normally sterile body sites
anything “inside” the body
– blood
– cerebrospinal fluid
– vitreous fluid (eye)
– joint (fluid / tissue)

Body sites with bacterial flora
i.e. commensal flora is
present
anything “outside”
– skin – whether intact or
ulcerated
– secretions from the body
- drains

Question 2

Types of swab

Answer 2

• viral culture: Viral transport media (VTM)
• anaerobe: gel swab
• PCR: UTM or VTM
• aerobic culture: dry or gel swab
• Blue Rayon bud (tip) with plastic shaft and
  Amies transport medium w gel: anaerobic and aerobic culture only
• reddish UTM media: for viral culture or viral PCR only

Question 3

How to swab exposed wound

Answer 3

How to take a swab of an exposed wound with signs of infection:
1. Clean away superficial debris – Swabs of wound exudate (taken before cleansing the wound) will detect SURFACE organisms, while the true pathogens will be in the deeper tissues
2. Sample the most representative part.
3. A deep swab is better –Bacteria causing infection is more likely to be in the viable wound tissue
5. Swab with firm pressure, using an approximate area of 1 cm2. Rotate the swab.
6. Press into wound to obtain fluid (if any).

Question 4

Urine sample sterile and non-sterile sites

Answer 4

Sterile: renal aspirate, supra-pubic aspirate

non-sterile: midstream, clean catch, in-out catheter

Question 5

MCS turnaround time

Answer 5

Non-culture tests
- Blood tests
1-3 days
- Microscopy
1-2 days
- PCR
1-3 days

Culture
- Aerobic culture
2-5 days
- Viral culture
7-21 days
- TB culture
10-42 days

Question 6

Urine dipstick interpretation
UTI is usually associated with
___ (white cells) in urine.
There may be associated
haematuria.
__ __ __ is often an indication of sample contamination

Answer 6

UTI is usually associated with
pyuria (white cells) in urine.
There may be associated
haematuria.
Mixed bacterial growth is often an indication of sample contamination