Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

70 Cards in this Set

  • Front
  • Back
Significant Components?
Positive Test?
Phenylethanol Agar:
-Selects for Gram +
Phenylethanol inhibits Gram neg growth
- Growth is a positive test
Eosin Methylene Blue Agar:
-Sel for Gram - and Diff for Lactose ferm
-Dark Colony: Lactose ferm (MB dye absorbs by high acid production) Pink Colony: Lactose ferm(absorbs Eosin by low acid production) No Dye Absorb: Lactose neg. (orangish)
Desoxycholate Agar:
-Selects for Gram - and Diff for Lactose ferm
-Red Colony: Lactose (+)
Non-Red Colony: Lactose (-)
Lipase Agar:
-Neutral Blue Dye
-Fatty Acid release lowers pH and Blue dye intensifies = (+)
-No Blue intensification= (-)
Milk Agar:
Clearing of opaque Milk = (+)
No Clearing of Opaque Milk = (-)
-Detect Gelatinase(hydrolyzes gelatin protein into amino acids)
No Resolidification=(+)
Nitrate Broth:
-Detect Nitrate Reductase (Nitrase) (converts nitrate to nitrite)
-Red w/o Zinc = (+)
Red with Zinc = (-)
Never turns red = (+)
Litmus Milk Broth:
moderate acid from lactose
pink liquid in tube
Litmus Milk Broth:
Heavy acid production from lactose
pink, hard or soft curds (Coagulation of casein by acid)
Litmus Milk Broth:
Alkaline products from metabolism
blue, liquid;
Litmus Milk Broth:
Reduction of litmus dye to colorless in lower half of broth = ?
viewed as whitish from natural milk color when the litmus dye is no longer in the oxidized colored state. This is the action of bacterial reductase in milk
Litmus Milk Broth:
Loss of opaque casein protein by caseinase?
proteolysis (patronization),
usually seen starting at the top and increases downward;
Litmus Milk Broth:
Detect Moderate/Heavy Acid from Lactose ferm. Detect Caseinase. Detect Reductase
Litmus Milk Broth
Slimy strands suspended in liquid state of medium ?
= ropiness trait produced by capsule-producing bacteria.
Urea Broth:
-Phenol Red: yellow = acid; cerise = alkaline; Red = neutral
-Red to Cerise = (+)
Yellow to light orange = (-)
Tryptone Broth:
-Detect Tryptophanase (hydrolyses tryptone to indole--Indole is what is tested for)
-Kovac's Reagent (added after growth)
-Red/cerise top = (+)
Yellow top = (-)
Methyl Red:
-Tests for Mixed Acid Fermentor
-Methyl Red (added after growth) (3-5 drops) pH below 5.0=Red
-Dye stays red = (+)
Dy turns yellow = (-)
-Detect 2,3 Butanediol ferm by testing for acetoin (acetyl methyl carbinol)
-Red on top = (+)
No red = (-)
Simmon's Citrate Slant:
Growth on slant and Blue Color = (+)
No growth =(-)
Phenol Red Sugar Ferm:
Yellow = ferm (+)
Lt Orange to Red = Ferm (-)
Gas in tube = Gas production
-Detect Phenylalanase (phenylalanine deaminase) which converts phenylalanine to phenylpyruvic acid (PPA)
-10% Ferric Chloride (added after growth) (5-10 drops)
-Green = (+)
No color change to Ferric Chloride = (-)
-Detect Oxidase which removes hydrogen from different substrates
-dimethyl-p-phenylenediamine hydrochloride (Oxidase Reagent-Added after growth)
-BacteriaTurn Dark Blue to Black = (+)
Remain Colorless = (-)
Two Genera of Acid Fast organisms?

Two important species in one of the generas?
-Mycobacterium; Two important species = tuberculosis and leprae
Mycobacterium staining properties?
Do not gram stain well if mature because of high wax content within walls, if young appear as gram + tapered rods that sometimes fragment
Nocardia Staining properties?
Actually requires use of a less stringent decolorizer than acid alcohol to achieve the same results
Three genera of Spore forming organisms?
o Bacillus – Aerobic, gram + rod
o Clostridium – Anaerobic gram + rod
o Sporsarcinae – Cocci
_______ produces a metallic green sheen on EMB
E. Coli
(2,3)Butanediol Fermentors produce less acid so that the colonies have pale pink to lavender centers on EMB. Example?
Why can the partial clearing on Blood Agar sometimes appear green?
Partial clearing sometimes appears green due to partial reduction of hemoglobin in blood
An alkaline reaction can occur in sugar fermentation tubes due to?
utilization of the peptone in the broth and not the testing sugar.
What is tested for when determening if something is a 2,3-butanediol fermentor?
acetyl methyl carbinol (acetoin) is easier to detect than 2,3 butanediol, acetoin is tested for when determining if a microorganism is a 2,3 butanediol producer.
Barrit's reagents?
VP1 = alpha-napthol
Oxidase is also known as? What is its function?
cytochrome oxidase
functions to oxidize aromatic amines
Nitrate 1?
Nitrate 2?
Nitrate I = Sulfanilic Acid
Nitrate II = dimethyl-alpha-naphthylamine
Kovacks Reagent is used for what test?
What is it?
-p-dimethylaminobenzaldehyde, amyl or butyl alcohol, and HCl, which will appear red (cerise) in the presence of the product indole
cystine desulfurase?
removes the sulfur side chain from cysteine to produce H2S --> in presense of iron forms BLACK precipitate
Organism that is H2S positive?
Tests for Sulfur (H2S production), Indole, and Motility
Primary indicator of citrate utilization is?
Growth on the media
Oil immersion lens uses oil with ___________________ refractive index as glass to prevent light loss due to diffraction (bending of light rays) which would occur if light traveled from _________ to _________
-approximately the same
-one refractive index to another
As magnification of the objective lens increases, the working distance (distance between the object on slide and the objective lens, when in focus) ______________
directs light towards the objective lens in bright field microscopy
Iris Diaphragm (lever located in the condenser)
adjusts the diameter of the cone of light so that it just fills the objective lens
As you close down the diaphragm:
1. The light intensity _______?
2. Contrast __________?
3. Depth of field __________?
As you close down the diaphragm:
1. The light intensity decreases
2. Contrast improves
3. Depth of field increases
4. Limit Resolution (with oil immersion lens)
Cationic Dyes?
Methylene Blue, Crystal Violet
Anionic Dyes?
Acid fuschin, Congo Red, Nigrosin
Fat Soluble Dyes?
Sudan Black stains granules of Poly-B-OH-butyric acid
Insoluble Dyes?
India Ink (colloid suspension of carbon particles)
Two dyes used in negative staining?
o Nigrosin – a black anionic (negatively) charged dye. The negatively charged dye is repelled by the negatively charged surface of the bacterial cell
o India Ink – an insoluble dye (a colloidal suspension of carbon particles) which does not penetrate the cell surface
What type of staining is best for determining morphology (shape and size)?
Gram-positive microorganisms have a ________ peptidoglycan and ______ lipid content than gram-negative microorganisms
Gram neg. cells are easily decolorized because?
the ethanol dissolves the high lipid cell wall allowing the crystal violet-iodine complex to readily exit the cell
Acid Fast microorganisms have____________________, which requires the use of steam to allow dye to penetrate the cell
a high wax content in their walls
Tests for?
Normal color and Positive indicator?
Bismuth Sulfide Agar:
-Tests for Salmonella typhi
-Normally dull green, S. typhi produces black or brown color
Positive tests?
Brilliant Green Agar:
-Differential for lactose/sucrose fermentation
-Lactose ferm procude yellow/green colony/media
-Sucrose Ferm produce red/pink/white colony + red media
SS Agar
Salmonella produces a black colony
Shigella a colorless colony
Lactose (+) colonies appear red
Desoxycholate CITRATE
Selects for gram (-), lactose (-)
Do lactose (+) grow on desoxycholate citrate
Some Lactose + colonies do grow but they will appear Red
Coagulates is only valid on?
Test is only valid on gram + staphylococcus like bacteria since gram negative bacteria are able to provide false positive reactions from a non coagulase like mechanism.
Positive test?
Manitol Salt Agar:
-Selects for staph d/t high salt concentration 7.5%
-Phenol Red
-plate/colonies turn yellow due to sugar fermentation
Positive test?
Staph 110:
-selects for staph and allows to observe natural colony color
-no indicator
M-staphylococcus broth
Enriched media containing 10% NaCl, which selects for Staphylococcus since Staphylococcus prefer the higher salt concentration, which inhibits most other organisms
Endo Agar:
-Selects for gram (-)
-Differentiates lactose
-Lactose (+) = red colonies
-Coliforms produce golden metalic sheen
Only staph species that can coagulate plasma?
S. aureus
Staph and Strep results for catalase/NO2 reductase?
Strep = (-)(-)

Staph = (+)(+)
facultative anaerobe that ferments lactose to produce gas, and is a gram negative, non-spore-forming rod
two coliforms?
Eschericia coli and Enterobacter aerogenes
mENDO Agar
pink medium that shows coliforms as a golden sheen
mFc Agar
light blue medium that shows fecal coliforms as darker blue colonies
The MIC is the ?
the most dilute (the minimal concentration) tube which prevents growth of the test organism