4/3 PL Quiz Flashcards
This is a test designed to differentiate bacteria on the basis of fermentative or oxidative metabolism of carbohydrates
Oxidation-fermentation (O-F)
How are organisms oxidized
Glycolysis, oxidation of pyruvate, citric acid cycle, electron transport chain
What does the O-F medium include
High sugar to peptone ratio to reduce the possibility that alkaline products will neutralize weak acids
When is bromothymol blue dye yellow
6
When is bromothymol blue dye green
7.1
When is bromothymol blue dye blue
7.6
What is the OF medium prepared with
Glucose, lactose, sucrose, maltose, mannitol, or xylose
What is one tube of OF sealed with and why
Later of sterile mineral oil to promote anaerobic growth and fermentation
What is the OF test used to do
Differentiate bacteria based on their ability to oxidize or ferment specific sugars
When it is green or blue sealed OF
Oxidation
When it is yellow throughout in sealed OF
Oxidation and fermentation or fermentation only
Slightly yellow at the top of sealed OF
Oxidation and slow fermentation or slow fermentation only
Green or blue sealed AND unsealed of OF
No sugar metabolism
MacConkey agar and EMB agar are selective for what
Gram negative organisms
What does the MacConkey agar contain
Lactose, bile salts, neutral red and crystal violet
What inhibits the growth of gram positive in MacConkey agar
Bike salts and crystal violet
When is neutral red dye colorless and red
Colorless above 6.8 and red below 6.8
What is MacConkey agar used to isolate
Members of Enterobacteriaceae based on the ability to ferment lactose
Poor growth or no growth in MacConkey
Gram positive
Good growth in MacConkey
Gram negative
Pink to red growth with or without bile precipitate
Probable coliform
Growth is colorless
Noncoliform
What are systems designed to run an entire battery of tests simultaneously
Multiple test systems
Why are multiple test systems beneficial
They are databases for fast and easy identification
What is the api 20 E system
Plastic strip of 20 micro tubes and cupsules, partially filled with different dehydrated substrates
What is added to the micro tubes
Bacterial suspension which rehydrated the media and inoculates them at the same time
These do not require the addition of reagents
Spontaneous reactions
What happens when the info can not identify the organism
Organism is grown and examined in MacConkey agar and supplemental tests are performed
What is the api 20 E system used for
Clinically for the rapid identification of enterobacteriaceae and other gram negative rods
