-Consider to be test for chemical reactions and product pathways.
-Used to identify gram negative organisms that look alike under the microscope.
-Each organism will react differently with all these test allowing proper ID and treatment
-gram negative organism found in the intestines.
-Other organisms outside this family can test positive for the MR-VP or other test.
Enterobacteriaceae that are MR+
-All ferment formic acid to mixed acid
Enterobacteriaceae that are VP+
-All ferment formic acid to butanediol
Enterobacteriaceae that are MR- VP-
Enterobacteriaceae that are MR+ VP+
Organisms not part of Enterobacteriaceae Family
MR- and VP-
Sugars: Mannitol tube
-bacteria use many sugars
-Mannitol tubes contain individual sugars
-Phenol red indicator will change color if acid is produced and pH lowers
-Yellow: sugar fermented..acid produced.. Positive Test
-Red: sugar was not fermented.. Negative Test
Placed upside down in mannitol tube to capture gas production. Presence of air pocket means gas was produced.
-Triple Sugar Iron
lactose and sucrose in the slant
Phenol red in the pH indicator
-The results are abbreviated:
K- means alkaline (red color)
A- acid (yellow color
TSI Results: red slant/ yellow butt (K/A)
Means glucose was fermented
TSI Results:yellow slant/yellow butt (A/A)
Means that glucose and lactose OR sucrose was fermented
TSI Results: red slant/red butt (K/K)
Means no sugar was fermented
TSI Results: if gas is present
it will split the agar or move the butt off the bottom of the tube. When right the results in (A/A) format you circle the 2nd letter.
TSI Results: H2S (Sulfur) produced
Media turns a black color. A plus sign is added to the bottom letter (A/A+)
Organisms that test TSI: (K/K)
Organisms that test TSI: (K/A)
Organisms that test TSI: (K/A+)
Organisms that test TSI: (A/A gas)
Organisms that test TSI: (A/A +)
Organisms that test TSI: (A/A)
-Determines of an organism produces the enzyme gelatinase
-Must refrigerate before reading results since gelatin is liquid at room temp.
-Solid gelatin (looks like jello): Negative
-Liquid gelatin: Positive
Gelatin (gelatinase) -> polypeptides and single
Gelatin + organism
Gelatin - organism
Methyl Red (MR)
-MR turns red when pyruvate is broken down to lactic acid, succinic acid, ethanol, acetic acid (the mixed acids)
-thus it checks for mixed acid fermentation.
-pH below 5 turns broth red when methyl red reagent is added
-gently swirl to make sure the red c
MR + organisms
MR - organisms
Glucose ->pyruvate->formic acid -> acetaldehyde->lactic acid, succinic and acetic acid
-Positive when pyruvate is converted to acetoin and carbon dioxide.
-checks for butanediol fermation
-Detects acetoin as end product that will not be used in any further reactions.
Voges-Proskauer (VP) Process
-Add Barritt's reagent:
Base: KOH (Potassium hydroxide)
-Let stand for 15 min so pink/brown color can develop
-Pink to brown: +
Voges-Proskauer (VP) Reaction
Glucose ->pyruvate->formic acid -> acetaldehyde->acetolactate->acetoin->butanediol
VP + organisms
VP - organisms
-determines ability to utilize citrate as sole carbon source
-Ammonium salts supply the nitrogen
-contains bromothymol blue indicator
-tells if organism produces citrate permease
-when citrate is remove from medium carbon dioxide is produced, which combin
Citrate Slants Result Colors
-slant turns a prussian blue color if positive
-slant remains teal green if negative.
Citrate Slants + organisms
Citrate Slants - organisms
Citrate Slant Reaction
Citrate->oxaloacetic acid and acetic acid
Oxaloacetic acid -> pryuvate and CO2
CO2 + Na and H2o -> Na2CO2 which increase pH and causes the color change
Testing Indole, Methyl Red, Voges Proskauer, Citrate
Escherichia Coli: ++--
Edwardsiella, Morganella: ++--