The flashcards below were created by user
cbennett
on FreezingBlue Flashcards.
-
Oxidative catabolism requires what to grow bacteria
oxygen
-
Fermentative catabolism uses what to grow bacteria?
starch hydrolysis (either peptone or glucose)
-
Fermentation of bacteria using peptone does what to the medium?
- Turns OF-glucose medium green to blue
- pH goes up (alkaline)
-
Fermentation of bacteria using glucose
- Turns OF-glucose medium green to yellow
- pH goes down (acidic)
-
How can organisms that don’t use starch grow on a starch agar plate?
They use peptones
-
MRVP broth (RED) is used to determine the energy source ??? in fermentation
- organisms that produce large amounts of acid from glucose
- Remains red = positive and pH below 4.4 (acidic)
- Turns yellow = neutral and pH above 6.0 (alkaline)
-
Citrate agar (GREEN) is used to determine the energy source ??? in fermentation
- Citrate use
- Bacteria with the enzyme citrate lyase can break down citrate to form pyruvate
- Turns blue = positive for the use of citrate acid
-
During prolonged periods (greater than 24-hours) what may happen to the bacteria in a fermentation tube?
- Exhausts the carbohydrate supplied
- Grows oxidatively on the peptone
- Turns red because of ammonia production
-
-
-
-
-
-
chemical agents used on inanimate objects to lower the level of microbes on their surfaces?
disinfectants
-
chemicals used on living tissue to decrease the number of microbes
antiseptics
-
Refers to agents used to kill bacteria
bacteriocidal
-
Agent causing temporary inhibition of growth
bacteriostatic
-
Variables to consider in selecting an antimicrobial agent
- pH
- solubility
- toxicity
- organic material present
- length of contact
-
Explain Disk-Diffusion method
- Petri plate with agar
- Inoculate uniformly over entire surface
- Impregnate with paper disks (ABX, mouthwash, etc.)
-
What is the Minimum Inhibitory Concentration (MIC)?
the lowest concentration of an antimicrobial that will inhibit the visible growth of a microorganism
-
Name bacteria that reside on the skin
- propionibacterium
- staphylococcus aureus
- staphylococcus epidermidis
-
Why is S. Aureus different than the other microbiota of the skin?
produces coagulase (enzyme that clots is pathogenic)
-
What allows bacteria of the skin to survive?
- resist drying
- acidic
- salt tolerant
-
What bacteria primarily exist at the back of the throat?
- Staphylococcus
- Streptococcus
- Neisseria
- Haemophilius
-
Beta-hemolytic group A streptococci (GAS) is which type of strep?
S. pyogenes
-
The importance of S. Pyogenes?
- Most pathogenic bacterium in the whole genus (strep throat to toxic shock to necrotizing fasciitis)
- Causes most Strep infections
-
Greenish color around colonies on blood agar, partial destruction of RBC's is what type?
Alpha hemolysis
- S. pneumoniae
- S. veridians
-
complete hemolysis of RBC's on blood agar, a clear zone around the colony is what type?
Beta hemolytic
S. pyogenes
-
no hemolysis and no change in the blood agar around the colony is what type?
Gamma hemolytic
-
S. pneumoniae vs. S. pyogenes
S. pneumoniae will turn green on blood agar where S. pyogenes will have a clear zone around colony
- S. pneumoniae
- Optochin sensitivity
- Bile solubility – activates an enzyme that lyses the cell wall
- S. pyogenes
- Sensitive to bacitracin – no others are
-
What is the purpose of the Enterotube?
- Rapid identification
- Large number of results from one inoculation
-
a protein enzyme that enables the conversion of fibrinogen to fibrin
Coagulase
-
What does it mean when coagulase causes clumping?
positive result - used to distinguish between different types of staph
-
a common enzyme found in nearly all living organisms exposed to oxygen
Catalase
-
What is the result if Catalase causes bubbles?
- positive result
- It catalyzes the decomposition of hydrogen peroxide
-
What is the test that estimates the concentration of antibody in serum?
agglutination titration
-
Why is the agglutination (titer of antibodies) titration test done?
- Used to determine whether a particular organism may be causing the patient’s symptoms
- An increase in titer in successive days is most likely a positive result
-
Simple dilution problem...
- 1ml bacteria added to 9ml nutrient broth = 1:10
- take 1ml of that dilution add to 9ml = 1:100…10x10x10x10x10 = 1:100,000
- number of colonies on plate of 1:1000 dilution is 54,
- then the count is 54 x 1000 = 54,000 bacteria/ml in sample
|
|
