Quantitative Methods Flashcards
1
Q
What are some examples of enumeration techniques ?
A
- pour plate
- spread plate
- Miles & Misra
- quantitative loop
2
Q
Describe Urinary Tract Infections
A
- very common
- most commonly caused by E.coli
- catheters predispose UTIs
3
Q
How can a sample be acquired to test for UTIs?
A
- midstream
- catheter
- suprapubic aspirate = directly from bladder - young children
- Early morning urine
4
Q
Why is it important to transport urine samples to the lab quickly ?
A
- urine is a good growth medium
5
Q
What lab investigations are used to diagnose UTIs?
A
- microscopy
- Culture - blood agar, MacConkey, CLED
- 37 degrees for 18 hrs
6
Q
How is Total Cell Count using a haemocytometer achieved ?
A
- add small sample of suspension to sample injection area
- examine under x40 objective
- count 80 small squares
7
Q
What are some examples of viable counts ?
A
- growth of bacteria from a suspension onto plates
- a single bacterium grows to give visible colony
- count colonies & extrapolate back to original suspension
8
Q
Describe the process of Bacteruritest Strips
A
- sterile paper strips 7.5cm x 0.6cm
- dipped in urine, end inoculated onto CLED
- incubated overnight at 37 degrees
- 20 or more colonies per sample is significant
9
Q
Describe the pros of a spiral plater
A
- rapid enumeration without manual dilutions
- saves on agar, Petri dishes & pipettes
- automatic sampling, disinfecting & rinsing
10
Q
Describe Most Probable Number (MPN)
A
- estimating numbers in food, water, wastewater
- serial dilutions made in medium
- 3 tubes incubated for each dilution
- dilutions scored for growth/no growth
- scores are used in MPN calculation to determine how many viable cells were in original sample
