Lab Final Flashcards
Define erythroblastosis fetalis.
Fetal RBC destruction
Eosin Methylene Blue Agar meaning?
Poor/no growth, inhibited by eosin and methylene blue, Gr +
Good growth, not inhibited by eosin and methylene blue, Gr -
Green metalic growth, ferments lactose with acid, coliform
What does the GasPak Anaerobic System do?
Creates anaerobic, microaerophilic, or CO2 enriched conditions
What is EMB used for?
Fecal coliform
How is a motility test done?
Stabbing the broth with a straight needle.
When is blood agar used?
Isolation and cultivation of bacteria; Differentiate bacteria based upon hemolytic characteristics
With wet mount and hanging mount looking for motility, what could cause a false negative?
Water dries up.
Too many microbes on slide - no room to move.
If a culture is too old or cold.
What is the Acid-Fast Stain Technique?
C A M
Heat fix, carbolfuchsin, water, alcohol, water, MB, water, blot
What is in the GasPak?
sodium borohydride and sodium bicarbonate
The incubation of nitrate broth after the addition of reagents and zinc, what is the positive result?
No color change
How is this broth described?
Flocculence (clumping)
What is the name of the bacteria that grows between 20 degrees and 45 degrees C.?
Mesophiles
What is EMB used for?
Fecal coliform
Can antimicrobial disk diffusion be determined by the clearning method alone?
No. A dimetral intrepretertive chart is needed.
What kind of broth is phenol red?
Differential
Decarboxylation test tubes. What is the meaning?
No color change, no decarboxylation, -
Yellow, fermentation; no decaroboxylation, -
Purple, decarboxylation w decarboxylase, +
What is EMB used for?
Fecal coliform
In Ex. 1-1, what was the purpose of the hand cleaning agents exercise?
Evaluate the effectiveness of a variety of hand-washing agents
What is the Endospore Stain Technique?
Phenol Red Broths meaning?
Seletive or differential?
Yellow broth, bubble in tube, fermentation with acid gas, A/G
Yellow broth, no buble in tube, fermentation w acid and no gas A/-
Red broth, no bubble in tube, no fermentation, -/-
Pink broth, no bubble, degragation on peptone, K
Differentiate Enterobacteriaceae
How is a wet mount made?
By placing a drop of water on a slide and covering it with a cover slip
If you get good growth in eosin methylene blue, EMB, what is the presumptive ID?
Gram negative
Sketch the Quadrant Streak Pattern
How is a hanging drop slide prepared?
Depression slide with a petroleum jelly ring.
Droplet is hanging on cover slip and not toughing the slide.
At what pH does Neural red indicate?
Indicates red at pH less than 6.8 - acidic conditions
What does eosin methylene blue, EMB, contain?
Gelatin, lactose eosin Y and methylene blue
What microbe does MacConkey agar detect?
Enterobacteriacease to ferment lactose
Sketch the Simple Streak Pattern
Note: no cross streak as seen in photo
What is the formulas for Dilution and Origional Cell Density
V1D1 = V2D2
OCD = CFU / (D x v)
MacConkey Agar meaning?
Is it selective and/or differential?
Poor/ no growth, inhibited by CV, Gr +
Good growth, not inhibited by CV, Gr -
Red, produces acid from lactose fermentation, coliform
Selective and differential for Enterbacteriaceae
What is the negative stain technique?
SOSD
Negrosin, add organism, slide, dry
In Ex. 1-1, hand cleaing agent, what is a positive result look like?
Any finger contamination that grows on nutirent agar is a positive result
Blood agar meaning?
List the five types of oxygen tolernace and draw each
Define decontamiantion
The reduction of the number of pathogens to a level to handle without PPE
What does the fermintation of glucose begin with?
Pyruvate
How do you test for an environment favorable for streptolysins?
Streak-stab technique.
Catalase Test meaning?
What is catalase?
Bubbles, catalase is present, +
No bubbles, catalase is absent, -
Catalase converts hydrogen peroxide H2O2 to H2O and O2
Nitrate Reduciton Test tubes with zinc meaning?
Red, nitrate reduction to nitrite, +
After adding zinc, no color change, nitrite to nitrogen, +
After adding zinc, red color, no nitrate reduction, -
What is in the GasPak?
sodium borohydride and sodium bicarbonate
What is the heat fixing technique?
Loopful of water, bacteria, air dry, flame
What causes hemolysis?
Streptolysin O - oxygen labile, anaerobic conditions
Streptolysin S - oxygen stable, anaerobic conditions too.
What is tested in blood agar? Which type has the most, middle, and no hemolysis?
Hemolysins to break RBC. beta-, alpha-, gamma-hemolysis has no media change.
How can motility be best observed?
using low or high-dry lenses
MacConkey agar uses neural red dye. At what pH does it indicate?
0-6.8 pH. Organisms that ferment lower the pH.
Citrate Utilization Test meaning?
Selective or differential?
Blue, citrate is utilized, +
No color change, citrate is not utilized, -
Differentiates Enterobacteriaceae
What is phenol red used for?
To differentiate enterobacteriacase from other Gram-negative rods.
Tripple Sugar Iron Agar meaning?
What is the name of the bacteria that grows between 0 degrees and 20 degrees C.?
Psychrophiles
Starch Hydrolysis (Amylase Test) meaning?
Clearing around growth, alpha-amylase present, +
No clearing, no alpha-amylase present, -
alpha-amalyase hydrolyze starch
Which microbe is motility an important characteristic?
Enterobacteriaceae
Gelatine Hydrolysis (Gelatinase Test)?
Geletin is solid, no gelatinase is present, -
Gelatin is liquid, gelatinase is present, liquidfaction, +
What is a disinfectant?
A germicide for use on surfaces.
Taken from an anaerobic jar, how are these cultures described?
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 Brownian motion?
Microbe collisions with water molecules.
Microbes vibrate in place, not swim
Sketch the three domains of life, include supergroups, and prokaryotes and eukaryotes
What is the name of the bacteria that grows between 50 degrees and 60 degrees C?
Thermophiles
What is the Capsule Stain Technique?
Sheep serum, congo red, slide, Maneval stain, water dry
What is phenylethyl alcohol agar, PEA, used for?
To isolate staphylocci and streptococci