Clinistripes quantitatively test for sugar in urine.
The Kastle-Meyer test tests for the presence of blood.
Salicylate testing is a category of drug testing that is focused on detecting salicylates such as acetysalicylic acid for either biochemical or medical purposes.
Iodine solution tests for starch.
The Van Slyke determination tests for specific amino acids.
The Zimmermann test for Ketosteroids
Seliwanoff's test for differentiating between aldose and ketose sugars
Test for fat: add ethanol to sample, then shake; add water to the solution, and shake again. If fat is present, the product turns MILKY WHITE.
Commonly Used Tests for Aerobic, Gram-positive Cocci Catalase positive Taxos A positive Optochin positive Bile Esculin positive 6.5% NaCl positive Bile solubility positive PYR & LAP positive Coagulase positive Catalase negative Vancomycin positive Optochin negative Bile Esculin negative 6.5% NaCl negative Bile solubility negative PYR negative & LAP positive Coagulase negative
Commonly Used Tests for Aerobic, Gram-Negative Cocci Oxidase positive (Gordon & McLeod's Reagent) Polysaccharide from Sucrose positive Rapid Sugars Polysaccharide from sucrose negative
Standard Biochemical Tests for the Enterobacteriaceae Indol Methyl Red Triple Sugar Iron agar (TSI) Motility Phenyl Red Carbohydrate Broth Malonate Broth Voges-Proskauer Simmons Citrate agar Lysine Iron agar (LIA) Phenylalanine
Standard Biochemical Tests for the Nonfermentative Gram-negative Bacilli Nitrate positive (before zinc) Nitrate positive (after zinc) Triple Sugar Iron agar (TSI) Decarboxylase Broth (Moeller) positive 42° C positive Acetamide positive Oxidase positive (Kovacs reagent) Nitrate negative Motility Decarboxylase Broth (Moeller) negative 42° C negative Acetamide negative Oxidase negative (Kovacs reagent)
-WE ARE BASICALLY GOING TO FOCUS ON SELECTIVE AND DIFFERENTIAL MEDIA, THE CATALASE TEST AND THE IMViC TESTS
Uses of selective & differential medium The use of media that is both selective and differential not only selects for a particular group or species of organisms, it also reveals specific metabolic information that can point to a particular species. For example, MSA (Manitol Salt Agar) is selective for Gram positive organisms from the family Micrococcaceae and differential for Staphylococci. The Atlas describes the composition and characteristic results of various selective and differential media.
Selective Media Culture medium that allows the growth of certain types of organisms, while inhibiting the growth of other organisms. -dyes in the medium. For example, methylene blue in EMB & crystal violet in MacConkey's. -high salt concentration in the medium. For example, 7% salt in MSA inhibit the growth of unwanted microorganisms.
Differential Medium Culture medium that allows one to distinguish between or among different microorganisms based on a difference in colony appearance (color, shape, or growth pattern) on the medium. -dyes in the medium. For example eosin/methylene blue in EMB. -pH indicators change the color of the medium as sugars in the medium. For example, lactose in EMB & MacConkey's and mannitol in MSA are fermented to produce acid products.
Hemolysis with Blood Agar -not selective -differential for: hemolysis - based on the ability to break down hemoglobin or red blood cells, 3 groups of microorganisms can be described *alpha-hemolysis: bacteria partially break down hemoglobin leaving a green pigment around the colonies * beta-hemolysis: a clearing is seen around the colonies as bacteria produce a "beta-hemolysin" which lyses the red blood cells * gamma-hemolysis (no hemolysis): no hemolysis is observed, bacteria do not produce a hemolysin
Catalase is an enzyme that breaks hydrogen peroxide into water and oxygen gas. Hydrogen peroxide is often used as a disinfectant in wounds, the bubbling that is seen is due to the evolution of oxygen gas. Hydrogen peroxide can wreak havoc in a cell, therefore any cell that uses oxygen or can live in the presence of oxygen must get rid of the peroxide. One of those ways is to make catalase. Organisms which produce catalase will bubble when placed into hydrogen peroxide. The catalase test is primarily used to distinguish among Gram-positive cocci: Member of the genus Staphylococcus are catalase-positive, and members of the genera Streptococcus and Enterococcus are catalase-negative.
The IMViC tests are a group of individual tests used in microbiology lab testing to identify an organism in the coliform group. A coliform is a gram negative, aerobic or facultative aerobic rod which produces gas from lactose within 48 hours. The presence of some coliforms indicate fecal contamination. The IMViC Tests
Enterics are Gram-negative bacteria that grow in the intestinal tract of humans and other animals. The IMViC tests is used to identify these microbes such as Klebsiella, Enterobacter, and Escherichia coli. IMViC tests is used to differentiate these three organisms. IMViC is an acronym that stands for indole , methyl red, Voges-Proskauer , and citrate . To obtain the results of these four tests, three test tubes are inoculated: tryptone broth (indole test), methyl red - Voges Proskauer broth (MR-VP broth), and citrate.
The Indole Test Test organism is inoculated into tryptone broth, a rich source of the amino acid tryptophan. Indole positive bacteria such as Escherichia coliproduce tryptophanase, which cleaves tryptophan, producing indole and other products. Kovac's reagent is then added to the broth. Postive results: Dark pink colour develops. *The indole test must be read by 48 hours of incubation
The Methyl Red and Voges-Proskauer Tests The methyl red (MR) and Voges-Proskauer (VP) tests are read from a single inoculated tube of MR-VP broth. After 24-48 hours of incubation the MR-VP broth is split into two tubes. One tube is used for the MR test and the other for the VP test. MR-VP media contains glucose and peptone. All enterics oxidize glucose for energy, however the end products vary depending on bacterial enzymes. Methyl red is then added to the broth. Bacteria that produce acid causes pH to drop below 4.4. Positive MR Results: Broth turns cherry red Bacteria which cannot grow in neutral pH breaks down the peptone, causing the pH to rise above 6.2. Negative MR Results: Broth is yellow in colour.
Reagents used for the VP test are alpha-napthol and potassium hydroxide. These reagents are added the broth. Positive VP Results: Reagents turn a pink-burgundy color (Acetyl methyl carbinol is present). *This may take 20 to 30 minutes to develop
The Citrate Test The citrate test is used to determine if a bacterium can grow utilizing citrate as its sole carbon and energy source.Simmon's citrate media contains bromthymol blue, a pH indicator. -Yellow at acidic pH's (around 6) -Blue at more alkaline pH's (around 7.6) Simmon's citrate agar has an intermediate green color. Positive Results: Agar turns blue Enterobacter and Klebsiella are citrate positive while E.coli is negative.
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