TSI Agar Exam 49 Questions with Verified Answers,100% CORRECT

TSI Agar Exam 49 Questions with Verified Answers What is the agar used in the Triple Sugar Iron Agar - CORRECT ANSWER TSI (triple sugar agar medium) slant medium What does the TSI agar diffrentiate - CORRECT ANSWER it differentiates bacteria based on sulfur reduction and glucose, lactose, and sucrose fermentation What is the substrate used in the TSI experiment? - CORRECT ANSWER Sodium thiosulfate What is the enzyme used in the TSI experiment - CORRECT ANSWER Thiosulfate reductase What is the reaction used in the TSI experiment - CORRECT ANSWER reduction What is the end product we are looking for the TSI experiment - CORRECT ANSWER H2S What is the indicator for the TSI experiment - CORRECT ANSWER Ferric ammonium citrate When testing for fermentation, the substrate of interest was - CORRECT ANSWER lactose, sucrose, and glucose The enzyme used for fermentation - CORRECT ANSWER varies The reaction we look for in fermentation is - CORRECT ANSWER fermentation The end product we look for in fermentation is - CORRECT ANSWER CO2 and acid the indicator used for this experiment is - CORRECT ANSWER phenol red Name two media that can be used to test for the ability to ferment lactose. - CORRECT ANSWER Any two of the following: EMB plate, MacConkey plate, phenol red lactose broth, and TSI agar slant Phenol red is what color under acidic conditions and what are acidic conditions? - CORRECT ANSWER It is yellow under acidic conditions, and acidic conditions are a pH under 7 What is the name given to the small inverted tube often put into sugar fermentation and what is its purpose? - CORRECT ANSWER It is a Durham tube, and its function is to collect any gas produced as a result of fermentation Phenol red is what color under alkaline or basic conditions and what are alkaline conditions? - CORRECT ANSWER It is hot pink under alkaline conditions, and alkaline conditions are a pH over 7 How is TSI agar inoculated and with what tool? - CORRECT ANSWER Stab and streak with an inoculation needle Which describes the appearance of a sucrose and glucose fermenting organism with TSI agar? - CORRECT ANSWER Acid slant and acid butt (yellow slant and yellow butt) What is often added to media that reacts with sulfur to produce a black color/ precipitate? - CORRECT ANSWER Sodium thiosulfate and iron Describe the appearance of a gas and sulfur producing glucose fermenter with TSI agar. - CORRECT ANSWER Unchanged slant and acid butt with black precipitate and breaks in the agar. (Red slant with yellow and black butt with breaks in the agar) What sugar fermentation does the butt of TSI agar reveal? - CORRECT ANSWER Glucose What other information- besides sugar fermentation does the butt of TSI agar reveal? - CORRECT ANSWER H2S production What sugar fermentation does the slant of TSI agar reveal? - CORRECT ANSWER Lactose and/or sucrose What does TSI stand for in TSI agar? - CORRECT ANSWER Triple sugar iron agar Purpose of TSI Agar? - CORRECT ANSWER differentiate bacteria on basis of glucose fermentation, lactose fermentation, sucrose fermentation, and sulfur reduction What color is a positive test in cysteine and sodium thiosulfate? - CORRECT ANSWER black What color is a negative test in cysteine and sodium thiosulfate? - CORRECT ANSWER no black What does the black color indicate? - CORRECT ANSWER acidic pH What is a positive test in glucose, lactose, sucrose? - CORRECT ANSWER some yellow (glucose only), all yellow (glucose and 1 dissaccharide) What is a negative test in glucose, lactose, sucrose? - CORRECT ANSWER no yellow What is the pH indicator in glucose, lactose, sucrose? - CORRECT ANSWER phenol red What does the color pink indicate? - CORRECT ANSWER alkaline What does the pink slate mean? - CORRECT ANSWER break down protein What does K/A pink and yellow in glucose test mean? - CORRECT ANSWER goes through pH reversion because runs out of glucose What is the substrate in the first Triple Sugar Iron Agar test? - CORRECT ANSWER cysteine and sodium thiosulfate What is the bacterial enzyme in the first Triple Sugar Iron Agar test? - CORRECT ANSWER cysteine desulfurase and thiosulfate reductase What is the end product in the first Triple Sugar Iron Agar test? - CORRECT ANSWER H2S What is the H2S indicator in the first Triple Sugar Iron Agar test? - CORRECT ANSWER ferrous ammonium sulfate What are the substrate in the second Triple Sugar Iron Agar test? - CORRECT ANSWER glucose, lactose, sucrose What are the bacterial enzyme in the second Triple Sugar Iron Agar test? - CORRECT ANSWER various endoenzymes What is the end product in the second Triple Sugar Iron Agar test? - CORRECT ANSWER acids Why are TSI cultures done? - CORRECT ANSWER To identify enteric bacteria which metabolize the triple sugars and release hydrogen sulfide Culture medium - CORRECT ANSWER TSI slants What 3 sugars are used in TSI cultures? - CORRECT ANSWER Lactose Sucrose Glucose Which pH indicator is used in TSI cultures? - CORRECT ANSWER Phenol red How are TSI slants inoculated? - CORRECT ANSWER "Streak/stab method" (Streak the slant Stab the agar with an inoculating needle) Purpose of TSI test - CORRECT ANSWER To identify and differentiate among the enterics based on the sugar fermentation pattern and the production of hydrogen sulfide gas Culture conditions - CORRECT ANSWER Incubate at 37 degs C with loose caps Possible reactions - CORRECT ANSWER Yellow butt end and slant: Positive for fermentation and produce acid products Yellow butt end and unchanged slant (orange-red color): Positive for fermentation in low concentration Black agar/sediment formation: Breakdown of ferrous ammonium sulfate meaning H2S (hydrogen sulfide) gas produced