Lecture 3-Diagnostic Microbiology Flashcards
What factors decide what culture will be used with a specific organism
1) source of sample tested
2) species suspected to be present in sample
3) nutritional requirements for said species
How are cultureS preserved?
By freezing them or keeping cold
Lyophilizer is fancy fridge name
Three steps of staining identification
- Make a smear
- Fix dried smear with heat
- Stain with desired dye
What is the simple staining method
Single dye normally used
All organisms same colour
Size, shape, number, arrangement
What is differential staining
Occurs when 2 different stains are used to differentiate two different types or parts of cells
What is the difference between grams negative and gram positive bacteria
.gram positive has a smooth cell wall with a large ration of petidoglycan whereas, gram positive has small ratio of peptidoglycan (smal’line) and ribbed cell wall
What are 3 other ways of staining
Flagella staining
Endosperm staining
Capsule staining
What is fluorescence microscopy
Dye fluoresces at specific wavelength, tagged antibodies
What is electron microscopy
Uses election beam rather then light) very precise
What 2 aspects are important when studying morphology in detail
- Absence or precense of certain traits help with identification
- Morphology( structure) impacts physiology and pathogenicity
What does morphology help science with/it’s use
I. Morphology helps to classify and identify (gram stain)
2. Gives clues to how cocci /bacteria behave in environment C capsules/endospores for example
What are some characteristics of bacteria
‘1. Small 2. Fast metabolism 3. Easter growth
What are the 3 basic shapes of bacteria
- Spherical (cocci)
- Red shaped (bacillus)
- Spiral (spirilum)
Define: chemically defined
All the chemical components are know in A growth
Define: chemicaly undefined
’ When components can’t be controlled or are unknown
Define enrichment media
Specific increase in a specific species of bacteria, isolate and multiply
Define psychrophiles
.bacteria that grows best between 15to20°C
Define mesophiles
Grow 25 to 40°C
Most bacteria belong here
Define hermophiles
40 to 85°C
Define aerobic micro organisms
-grow at normal atmospheric levels of oxygen
Define anaerobic microorganism
. Cannot live in conditions containing oxygen
Facultative microorganism define
Grow in aerobic and anaerobic conditions
Micro aerophillic organism
( Can use oxygen for chemical reaction
What is intracellular pH?
7.5
What are other factors that influence bacteria growth
. pH, water, osmotic pressure
