Safety and specimen management

Question 1

What are methods of sterilisation?

Answer 1

Dry heat
Moist heat

Filtration

Ionising gamma radiation/ UV

Question 2

What is difference between sterilisation and disinfection?

Answer 2

Sterilisation kills all microbes including spores

Disinfection kills most, but not all microbes

Question 3

Hazard coding system is a square with 4 boxes.

What do they represent?

Answer 3

top - flammable temperature

left - health hazard e.g hazardous, extreme danger, deadly

right - instability e.g unstable if heated, may detonate

bottom - specific information e.g oxidiser, acidic, corrosive

Question 4

T/F

• chlorhexidine gluconate can be used to cleanse skin before drawing blood
• fume hoods filter air, and remove pathogens before discharging it outside

Answer 4

• chlorhexidine gluconate can be used to cleanse skin before drawing blood T
• fume hoods filter air, and remove pathogens before discharging it outside F

Question 5

Standard precautions include the following except…

A hand washing after removing gloves
B using PPE when handling specimens
C wearing lab coat to cafeteria
D using automatic pipettor

Answer 5

C wearing lab coat to cafeteria

Question 6

Routine clinical specimens should be handled with precautions designated for…

• biosafety level 1
• biosafety level 2
• biosafety level 3
• biosafety level 4

Answer 6

• biosafety level 2
• biosafety 1 is suitable for undergraduate science
• 3/4 if for potentially infectious pathogens

Question 7

Microbiologists must be careful not to generate infectious aerosols. Practice that generate aerosols include the following except….

A hot looping (trying to quickly cool an innouclating loop by inserting into agar)
B votexing
C streaking a plate
D grinding tissue

Answer 7

C streaking a plate

Question 8

T/F

• bronchoscopy specimens should be centrifuged and sediment used to inoculate culture media
• urine culture represent semiquantitative technique

Answer 8

• bronchoscopy specimens should be centrifuged and sediment used to inoculate culture media T - this is to break down epithelial cells of lung
• urine culture represent semiquantitative technique F this is a quantitative technique, as know volume of liquid using specific inoculating loop

Question 9

What are three sources of laboratory contamination, during molecular testing?

Answer 9

Carryover contamination - PCR products of previous samples, can be aerosolised during pipetting, and travel over benches/ equipment contaminating clean lab equipment

Sample-sample contamination - manipulating sample in MSC Class I cabinet can contaminate cabinets, consumables and gloves

Template DNA - contamination from environment from lab staff, or reagents used in PCR assay

Question 10

How to reduce risk of lab contamination in molecular testing?

Answer 10

General -

• Unidirectional workflow - pre-amp to amp
• Use dedicated equipment e.g pipettes for each section

Specimens -

• Do not keep tubes/ reagents longer than necessary
• All reagents/ reaction tubes should be clearly labelled
• Centrifuge samples to remove droplets from lids

Cleaning -

• Clean regularly - e.g DNA away, UV-irradiation, sodium hypochlorite
• Environmental swabs for regular testing for contamination

Staff -

• Wash hands/ use gloves
• Lab coats
• training