Select and Inoculate Culture Media Flashcards
What helps you select the appropriate medium?
What was learned on the initial Gram staining
What else can you use to select the appropriate medium?
Oxygen requirements, and Nutrition
Oxygen requirements
Obligate aerobes Obligate anaerobes Facultative anaerobes Microaerophilic Capnophilic
Obligate aerobes
Bacteria that require oxygen to survive
Obligate anaerobes
Bacteria that are killed in the presence of oxygen or those with growth that is inhibited in the presence of oxygen
Facultative anaerobes
Organisms that can survive in the absence of oxygen, but their growth is limited
Microaerophilic
Bacteria that prefer reduced oxygen tension
Capnophilic
Bacteria that require high levels of carbon dioxide
Fastidious microbes
Picky eaters
Agar
Dried sea algae extract
General purpose media
Aka nutrient
Not common in vet med
Enriched media
Meets requirements of fastidious pathogens
What does enriched media meet the requirements of?
Fastidious pathogens
Selective media
Contains antibacterial substances
Differential media
Allows bacteria to differentiate into groups by biochemical reaction
Enrichment media
Favors the growth of a particular type/group of organisms
Transport media
Keeps microbes alive but does not encourage growth
What two media is Blood Agar?
Enriched (fastidious) and Differential (hemolysis)
What does Blood agar do?
An Enriched medium that is used to grow a wide variety of bacteria and a Differential medium based on hemolysis
What are the three different types of hemolysis seen with blood agar
Alpha
Beta
Gamma
Delta
Alpha hemolysis
Partial hemolysis
Beta hemolysis
Complete hemolysis
Creates a clear zone around the colony
Gamma hemolysis
Hemolysis that produces no change in the appearance of the medium and around the colonies
Delta Hemolysis
Double zone hemolysis
What two media is MacConkey Agar?
Selective and Differential
What kind of bacteria does selective media grow?
Gram negative
Lactose fermenting
Bacteria changes pink
Non-lactose fermenting
Bacteria does not change color
Eosin-Methylene Blue Agar (EMB)
A selective and differential medium used to isolate fecal coliforms
What does Eosin-Methylene Blue allow to grow?
Gram positive bacteria
Escheria coli
Klebsiella pneumonia
What color does E.coli and K. pneumonia colonies turn in a Eosin-Methylene Blue Agar?
Metallic Green
Thioglycollate broth
An enrichment broth used to determine oxygen requirements of microorganisms
Mueller-Hinton Agar
A general purpose medium used for culture and sensitivity testing of rapid growth bacteria
What is the Goal of inoculation?
Isolated colonies
How do you start the inoculation process?
Flame the wire loop and allow it to cool.
Collect a small amount of bacteria from an isolated colony from 1st agar plate, broth, or swab
What happens after you collect the bacteria for inoculation?
Make streak area 1 then flame the loop from near to distal
What do you with the loop once it is flamed?
Drag it once through area 1 and streak area 2.
After streaking the loop through area 2 what is the next step in inoculating?
Flame the loop and drag once through area 2 and make area 3
What do you do if you are doing the quadrant method?
Make area 4 by flaming the loop and label
How do you place the agar in the incubator?
Inverted
How do you remove the bacteria to inoculate the slant and butt?
With a small amount of bacteria using a sterile bacteriologic needle
Where do you stab the needle when inoculating a slant and butt?
Directly into the center of the agar tube.
- Push the needle all the way down to the bottom
- Withdraw the needle through the same way
How do you streak a slant and butt?
Using a back n forth motion starting at the bottom of the slant
What temperature should agar plates be incubated at?
37 degrees celsius
Why should agar plates be placed upside down?
To lessen the contamination risk from airborne particles landing on them
Prevent water condensation
Mesophiles
Grow in moderate temperature
Psychrophiles
Grow at a lower temperature
Thermophiles
Grow in a higher temperature
How do bacteria reproduce?
Binary fission
What are the four phases of bacterial growth?
- Initial/Lag phase
- Exponential
- The stationary phase
- The death/final phase
Initial/Lag phase
Adjust to the environment
Exponential
Increase in number of living bacterial cells, until space is used up or wastes accumulate
The Stationary phase
Plateau in the number of living bacterial cells
The Death/final phase
Exponential decrease of living cells
What stage are spores produced at?
The death/final phase
What are the characteristics of colonies?
Size Pigment Density Elevation Form Texture Odor Hemolysis
How do aerobic bacteria produce energy
With the use of oxygen
How do anaerobic bacteria produce energy?
Without oxygen
How is culturing anaerobes different than aerobes?
Anaerobic cultures need to be collected more quickly than aerobic cultures
What is else is different in culturing anaerobes and aerobes?
The growth medium
What is the growth medium for anaerobes?
Thioglycollate
What is the growth medium for aerobes?
Agar