Lab 2-14 5-3 5-8 5-28 Flashcards
What is a disinfectant?
A germicide for use on surfaces.
What is a antiseptic?
A germicide for use on living tissue.
What is the name of the chemical germicide lab?
The Use-Dilution Test
What organisms does the Use-Dilution Test used on?
In class, Staph epidermidis and E. coli
What is a positive result for the Use-Dilution Test?
A positive result will be the surviving bacteria will make the broth turbid, indicating the germicide did not kill the bacteria.
What is the purpose of the Use-Dilution Test?
Test the effectiveness of germicides against bacteria.
What is the pH range does phenol red indicate?
Yellow below pH 6.8 Pink above pH 7.4 Red between pH 6.8-7.4
What is the name of the tube used to collect gas?
Durham tube
What is the name of the gas produced and what does it do to the pH?
Ammonia, NH3 Raises pH, turning phenol red pink
What is phenol red used for?
To differentiate enterobacteriacase from other Gram-negative rods.
What does deaminization mean?
Breaks amino acids becomes more basic, raises pH, making the broth pink.
What kind of broth is phenol red?
Differential
What does the fermintation of glucose begin with?
Pyruvate
What does anaerobic respiration do?
Transfer of electrons to an inorganic molecule other than oxygen.
What kind of broth is nitrate broth?
Undefined beef extract, peptone, and potassium nitrate.
What is the name of the nitrate test?
Nitrate reduction
What does enterobacteriacease do to nitrate?
A one step reduction from nitrate to nitrite.
The incubation of nitrate broth after the addition of reagents and zinc, what is the positive result?
No color change
How is a motility test done?
Stabbing the broth with a straight needle.
What is a positive motility test result?
Red diffuse growth radiating outward from the stab line.
Which bacteria is examined for motility?
Enterobacteriacease
What is the chemistry for the motility test?
Reduction of 2,3,5 TTC by metabolizing bacteria changes from colorless to red insoluble formazan. The formazan is reduced (gains electrons)
What is the end product of fermentation?
Lactic acid, ETOH, CO2
What is a denitrifier?
Something that reduces NO3 all the way to N2.
What test looks for hemolysins?
Blood agar
What is hemolysis?
Lysis of RBC, turns blood agar clear around beta-hemolysis microbes.
What is incomplete lysis?
Alpha-hemolysis, greenish-black zone around colonies.
What is no hemolysis?
Gamma-hemolysis, no media change.
What causes hemolysis?
Stereptolysin O - oxygen labile, anaerobic conditions Streptolysin S - oxygen stable, anaerobic conditions too.
How do you test for an environment favorable for streptolysins?
Streak-stab technique.
When is blood agar used?
Isolation and cultivation of bacteria; Differentiate bacteria based upon hemolytic characteristics
