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69 Cards in this Set
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Catalase test: |
Positive Result:= Bubble formation after placing a drop of hydrogen peroxide on the colony Negative Result= No bubble formation after placing a drop of hydrogen peroxide on the colony on a glass slide |
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What does Catalase test for? |
to see if the microbe has catalase, a protective enzyme capable of destroying the dangerous chemical hydrogen peroxide.
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What is the reagent for catalase? |
Peroxide |
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Oxidase test: |
Positive Result = Purple edging effect after Kovac's reagent is added Negative Result= No edging effect after Kovac's reagent is added |
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What is the reagent for Oxidase? |
Kovac's |
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What does the Oxidase test for? |
used in microbiology to determine if a bacterium produces certain cytochrome c oxidases |
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Carbohydrate Fermentation test: |
Positive Result= Yellow color changes with or without gas production Negative Result= No color change |
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What does the Carbohydrate fermentation test for? |
To see is the bacteria can make the specific enzyme required to breakdown each carbohydrate; then it can USE the carbohydrate. Phenol Red- a pH indicator that changes from red to yellow to indicate acid production ( yielding positive result) |
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Starch Hydrolysis test: |
Positive Result= A clear halo around the colonies after the addition of Gram's Iodine Negative Result = The entire medium is dark blue/brown |
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What is the reagent for the Starch test? |
Gram's Iodine |
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What does the Starch test, test for? |
The purpose is to see if the microbe can use starch, a complex carbohydrate made from glucose, as a source of carbon and energy for growth. Use of starch is accomplished by an enzyme called alpha-amylase. |
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Nitrate Reduction Test: |
Positive Result for Nitrate ---> Nitrite= Yellow,pink or red color change after the addition of Paba. Negative Result for Nitrate--> Nitrite= No color change after addition of the Paba |
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What is the reagent for the Nitrate Reduction Test? |
Paba |
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What is the purpose of the Nitrate reduction test? |
Nitrate broth is used to determine the ability of an organism to reduce nitrate (NO3) to nitrite (NO2) using the enzyme nitrate reductase. It also tests the ability of organisms to perform nitrification on nitrate and nitrite to produce molecular nitrogen. |
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H2S Production (Peptone) test: |
Positive Result= growth with black precipitate in the media Negative Result= growth with no black precipitate |
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What is the purpose of the H2S Production test? |
the microbe reduces sulfur-containing compounds to sulfides during the process of metabolism. |
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Citrate Utilization test: |
Positive Result= Green to blue color change (citrate was utilized as sole carbon source)
Negative Result= No color change (citrate was not utilized)
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What is the indicator for the Agar used in the citrate test? And what does the Medium contain? |
Indicator= bromothymol blue; will detect a pH change greater than 7.5 from the conversion of ammonium dihydrogen phosphate to ammonia and ammonium hydroxide. |
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What is the purpose of the Citrate test? |
Simmons citrate agar tests for the ability of organism to utilize citrate as a sole carbon source. |
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Motility test: |
Positive Result= fanning out away from the stab line. This can also make the tube look cloudy Negative Result= No fanning out from the stab line ** there is a dye in the media that shows the color pink for growth. |
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Urea Hydrolysis test: |
Positive Result= Bright pink slant ( Urea Hydrolyzed, urease is present) Negative Result= Light orange to yellow color (Urea not hydrolyzed, no urease present.) |
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What is the purpose of the Urea Hydrolysis test? |
Using Christensen's urea broth, a media containing urea.The purpose is to see if the microbe can use the compound urea as a source of carbon and energy for growth. Use of urea is accomplished by the enzyme urease. |
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Phenylalanine Deamination test: |
*** reagent =FeCl3 Positive Result= Dark green color on slant (Phenylalanine metabolized to phenylalanine acid, phenylalanine deaminase present)
Negative Result= No color change (Phenylalanine not metabolized, phenylalanine deaminase is not present)
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What is the purpose of the Phenylalanine Deamination test? |
Used to detect the presence of phenylalanine deaminase. |
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BEA, Selective and Differential Media Bile Esculin: |
Positive Result= Growth (selective) of bacteria with a color change of the media to black (differential; Bacteria able to hydrolyze esculin and survive the bile salts, often Enterococcus spp.) Negative Result= Growth of bacteria without color change or no growth of bacteria (Bacteria unable to hydrolyze esculin or unable to grow in presence of bile. |
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What is the purpose of the BEA test? |
To test if the bacteria can survive in the presence of bile and hydrolyze esculin. |
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Mannitol Salt Agar (MSA): |
Positive Result= Growth of bacteria with a color change of the media to yellow Negative Result= Growth of bacteria without a color change or no growth of bacteria ( Bacteria unable to tolerate high salt or unable to ferment mannitol) |
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What is the purpose of the Mannitol Salt Agar (MSA) test? |
Isolation of some pathogenic Gram-positive organisms. Selective for salt-loving bacteria and differential for species that can ferment the Mannitol into acid (color change) |
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Eosin Methylene Blue Agar (EMB) Test: |
Positive Result= Growth of bacteria with a color change of the colonies that have dark centers (magenta or purple) or a metallic green sheen Negative Result= Growth of bacteria without color change (takes on media color) or no growth of bacteria |
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(MR) Methyl Red test |
Positive= red color change indicating mixed acid production Negative= no color change **yellow = neutral environment |
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What is the reagent for Methyl Red test? |
Methyl Red |
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What is the purpose of the MR test? |
To look for either acetoin or mixed acid production. |
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What is the purpose of the EMB ager test?
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used in identification and isolation of Gram-negative rods. EMB agar inhibits the growth of Gram-postivie organism (selective), and differentiates bacteria between lactose fermenting and non-lactose fermenting.
TWO indicator dyes: Eosin and methylene Blue Metallic green sheen = E.coli colonies |
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MacConkey Agar (MAC) test= |
Positive Result= Growth of bacteria with a color change of the media to bright pink Negative Result= Growth of bacteria without color change or no growth of bacteria |
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What is the purpose of the MAC agar test? |
It is also for the identification of lactose fermenting, Gram-negative enteric organisms, and for inhibiting growth of Gram-positive organisms. The red color is due to the pH indicators response to the acidic environment created by fermentation of lactose. |
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O/F Test |
Positive Result=growth in both tubes with and without mineral oil with color change from red to yellow.
Negative Result= No growth or only growth in the tube without mineral oil layer. No color change . |
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Purpose of O/F test?
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To test for the ability to oxidize and ferment lactose.
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Lactose, Glucose, Sucrose, Xylose, Trehalose test |
Positive Result= Growth with a color change of sugar broth from red to yellow and production of gas ( gas bubble in the Durham tube) Negative Result = No growth with no color change nor gas bubble. |
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List of types of Agars used: |
-Sheep Blood Agar (SBA) -Iron Peptone Agar (PIA) -Simmon's citrate agar ( SC) -Christenson's Urea Broth -Bile Esculin Agar (BEA) -Mannitol Salt Agar (MSA) -Eosin Methylene Blue Agar (EMB) -MacConkey Agar (MAC) -Brain Heart Infusion Agar (BHI) -Nutrient Agar (NA) -Thioglycolate broths -Tryptic Soy Agar (TSA) -Mueller-Hinton Agar (MH) *Antibiotic Infused
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For sugar Agars, what does the +/- mean? |
the left hand side is for color change, differential, and the right hand side is for gas production ( selective) |
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What does MPN stand for? |
Most probable number of contaminants (water samples) |
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Hemolysis= |
Some microbes contain enzymes that can lyse host cells, especially red blood cells. ---Test is done onSBA plates (Sheep blood agar) |
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Virulence factors |
are molecules produced by pathogens (bacteria, viruses, fungi and protozoa) that contribute to the pathogenicity of the organism and enable them to achieve the following: colonization of a niche in the host (this includes attachment to cells) |
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What was on the poop plate? |
Tetracycline; therefore, if there was growth, it was a tetracycline resistant anaerobe and a facultative anaerobe ( can grow in the presence of O2 but prefers no O2) |
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High copy number: |
plasmid that may have up to 300 copies of itself in any one bacterial cell, thus is can produce up to 300 copies of gene product that it carriers in that one bacterial cell. |
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pGlO: |
a plasmid that contains an ampicillin resistance gene, which codes for the exoenzyme ampicillinase. |
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Alpha hemolysis: |
incomplete |
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Beta hemolysis= |
complete |
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transformation: |
to move DNA around |
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What did the CaCl2 do in the experiment with transformation? |
Brings plasmids to cell wall so that when the sample is heat shocked, the pores open and the plasmids can enter. |
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AMPr gene: |
encodes for an ampicillinase ( becomes resistant to ampiciline) |
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pGLO gener --> |
GFP-Green flouresent protein (isolated in bioilluminesent; potential to glow) ---only transcribed/ translated in the presence of arabinose---> inducer (like an operon) |
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Indicator organism |
is one which is present in human waste in high enough numbers to be readily detected and east to find |
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Coliforms: |
are aerobic or facultatively anaerobic gram negative rods. They do not form endospores and they ferment lactose which leads to acid and gas production within 48 hours of incubation at 35 degrees Celsius. |
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multiple tube technique: |
a way to detect Coliforms. Involves two tests; a presumptive test in lactose broth and a confirmation test. Those tubes that test positive in the presumptive test (acid and gas production) go on to be confirmed using MUG (methylumbelliferyl-B D glucuronide) agar or EMB ( Eosin Methylene Blue) agar. |
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Gram Stain procedure: |
Crystal Violet Rinse Grams iodine Ethanol Rinse Safranin Rinse |
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Dilutions equation: |
CFU= # of colonies / (amount plated)(dilution factor) *** divide every time by 10 then; multiply each total to give the final mL. Plug in that ML for "dilution factor) the amount plated is a CONSTANT : 0.1 remember only can be 30- 300 colonies to be used for calculations. |
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Microaerophiles: |
require low concentrations of O2 fro growth. However, higher oxygen concentrations will inhibit heir growth and they cannot grow in the total absence of oxygen. |
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Capnophillic organisms: |
prefer higher concentrations of CO2 |
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Reservoirs |
are humans or animals that are sources of infection. |
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Vectors |
Diseases transmitted by insect and arthropod |
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Mechanical Transmission |
occurs when an insect carriers fecal pathogens on its feet and then walks on food. |
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Biological transmission |
occurs through the bite of an infected mosquito, tick, or flea |
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Endemic |
diseases are present in a population all the time at low levels. |
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Zoonoses |
are diseases of animals that can spread to humans. |
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aseptically |
without introducing other microbes |
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Autoclave |
steam and pressure. heated to 121 degrees C at 15 psi. for 15 mins can kill all microbes including spores. |
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Psychrophile- Mesophile- Thermophile- |
Cold-loving
Middle-temp loving Heat-loving |
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Disk-diffusion method |
used to determine the effectiveness of some antibiotics on certain bacteria |