Diagnosis and Management of Oral Disease III

Question 1

Good sampling practice?

Answer 1

Collect specimen prior to administration of antimicrobial therapy
Take specimen from actual infection site e.g. drainage from deeper site vs scab
Sample collection and transportation crucial as may impact quality, minimise contamination of microorganisms

Question 2

Fine needle aspirate - how much fluid to take and how to send it to the lab?

Answer 2

1ml

Put sheaf back on needle and tape it up

Question 3

Specimen features?

Answer 3

Prompt processing
Quicker specimen processed the better
Pathogens may die in transit = false negative results
If transport delayed, a transport medium should be used

Question 4

What is a transport medium? What does it contain?

Answer 4

Contain no growth supporting nutrients - maintains vitality without supporting grown

Reducing agent can be added to preserve anaerobes but allows aerobes to survive
CO2 can be included to support vitality of certain pathogens e.g. N.gonorrhoea
Gelatin/corn starch to absorb toxic metabolic products of the host

Question 5

How to sample pus?

Answer 5

Swabs

• Clean mucosa prior to incision
• Send in transport medium - water, isotonic salts, reducing agent

Aspirates

• Leave in syrige
• Make needle safe

Paper points
- Send in transport medium

Question 6

How to sample mucosa and skin?

Answer 6

Swabs

• Dry sites - moisten swab - standard transport medium e.g. angular chelitis
• Suspected viral - viral swab - viral transport medium - protein stabiliser, salts, gelatin, water OR vesicle fluid - aspirate into a tuberculin syringe

Oral rinse
- 10ml sterile saline, rinse mucosa 30 secs, spit into sterile bottle/tube - provides info on microbial load

Question 7

How to get samples to the lab?

Answer 7

Specimen request form

• State type of sample, where from, clinical signs and symptoms, provisional diagnosis
• Ask for culture and sensitivity
• Separate pocket of bag from specimen

Local lab
- Take ASAP - same day, refrigerate if delay

Post

• Label as diagnostic specimen or biological substance, category B
• Place in rigid container
• Wrap aspirates in absorbent material in case of leakage
• Itemise list of contents enclosed between the 2ndry and outer packaging

Question 8

What are category A infectious substances?

Answer 8

When exposure to it occurs, it can cause permanent disability, life-threatening or fatal disease to humans or animals

• HIV
• Hep B/C
• Mycobacterium tuberculosis

Only applies to cultures/concentrates - not swabs or aspirates from infected pts taken for diagnosis

Question 9

Lab results?

Answer 9

Preliminary possible after 24hr but normally at least 48hr required

• Microscopy
• Culture

Result will not give species
Will give sensitivity to common antibiotics