VTNE Vet Practical Practice Exam Questions and Answers

How do you perform a oxidase test - pick up colony with wooden stick -place on paper and add reagent Positive: purple color - means cytochrome oxidase enzyme is present Is this a positive or negative oxidase result Negative: no color change -lack enzyme Is this a positive or negative oxidase test result How to do a catalase test - pick colony up with wooden stick - place on slide and add one drop of 3% hydrogen peroxide Why don't you pick up blood agar from catalase RVC contains catalase and gives a false positive Positive: bubbling reaction - catalase enzyme is present Is this a positive or negative catalase result test Negative: no reaction occurred Is this a negative or positive catalase result test How to do a KOH test -place a drop of 3% HOH on a slide - using a loop add the colony -mix together positive: stringy - gram negative Is this a positive or negative KOH test result Negative: watery - gram positive Is this a negative or a positive KOH test result How to do a coagulase test - add rabbit plasma - incubate for 4 hours at 37 degrees Celsius -examine for coagulation ( coagulase interaction with the fibrinogen in the plasma ) Positive: fibrin clot ( partial or complete ) - positive for staphylococcus aureus Is this a positive or negative coagulase test result Negative Is this a positive or negative coagulase test result What does enterotube II perform 15 biochemical tests Citrate test Used to determine the ability of an organism to use citrate as its sole source of carbon Positive : blue color developed Is this a positive or negative citrate test result Negative: unchanged medium of green Is this a positive or negative citrate test result SIMS tube test Use a pick and stab straight down , draw pick out following same path Used to see... —Sulfide production — Indole test — Morality Sulfide production ( SIMs test ) Blackening of media Indole test ( SIMs tube ) Add 5 drop of Logan reagent to top of tube, red ring is positive for Indole Motility ( SIMs test ) Look at entire turbidity not just the stab line Positive: blue / bluish-green Is this a positive or negative Indole test result Negative: no change- pink Is this a positive or negative indole test result What does a TSI tube contain 0.17% glucose, 1.0% sucrose, 1.0% lactose How to do a TSI tube Stab the butt of the slant with a wire pick, withdraw and streak across the slant, cap loosely and incubate at 37 degrees C overnight TSI tube : red/ yellow Acid produce and sugar fermented TSI tube : black H2S production has What does. tSI tube describes - carbohydrate fermentation -B2S production +/- -H2S production Why do we use controls So that we can compare and contract the unknown with the known and accurately determine whether the unknown is gram negative or positive Standard time , temp, and pressure for autoclaving medias 121 degrees C, 15 minutes, 15 psi Standard incubation time 36/37 degrees C for 18-24 hours