Lecture 2 - Laboratory Flashcards
culture dependent
can grow organism in lab and study it
*Collect specimen > Isolate > Investigate / test > identify
culture independent
don’t need to grow it in lab to be able to identify and study it
*collect specimen> Investigate (test) > identify
what is important when it comes to specimens collection, why?
quality. Effects speed and accuracy of organism identification.
- contributes to better pt outcomes and avoids inappropriate treatment
what types of specimens can you collect?
throat swab, sputum, blood samples (sterile), wound swabs, urine, genital swabs, stool
what is an example of a sterile specimen, why?
blood sample.
arent in contact with bacteria, virus, fungus that is all over body – no chance for cross contamination.
– able to identify bacteria and such that isnt supposed to be in there
what are important details to label on specimen collection
- sources (niches) –> can aid in identification (rash vs cat bite)
- patient status can effect work up (healthy vs diabetic)
culture
a population of bacteria grown in defined medium and defined conditions in a laboratory
pure culture
growth of a single known species - what we want
mixed culture
holds two or more species (starting point)
-need to separate normal flora from causative agent
contaminated culture
includes unwanted microbes, usually introduced inappropriately
-living on pt but not actually the cause of infection
what is inoculation?
- how is it completed
- types?
Adding a small amount of sample (ex: urine, swab) to media to grow a culture
-only certain bacteria can grow on certain media
-Inoculated media is incubated to grow culture at 20 to 40 ºC, different atmospheres (aerobic, anaerobic)
Types of inoculation: Streak plate (\/\/\) Spread plate (L)
*goal is to isolate colonies
isolated colony
A population of cells on an agar plate that arise from division of a single cell
-dif species form colonies with distinct characteristics (morphology) like size and colour
what is colony morphology
- differs between species - an be used to identify causative agent
- media type also aids in identification (differential and selective or enriched)
differential media
- Contain chemicals that allow distinction of different types of bacteria based on colony morphology (d/t specific trait like metabolism)
ex) mackonkey agar - identify lactose fermentation or not
Selective Media
- prevents growth of a specific group of microbes, while allowing growth of others
- target general groups (gram + or gram - or staphylococcus)