Testing

Question 1

IMViC (Indole, Methyl Red, Voges Proskauer, Citrate)

Answer 1

key to determination of id within Enterobacteriaceae group; methyl red may be omitted in certain test systems

Question 2

Indole

Answer 2

determines ability of organism to split trytophan to form indole; positive has a red ring; (+) E. coli

Question 3

Methyl Red

Answer 3

determines ability to produce and maintain stable acid end products and neutral end products from glucose fermentation, as well as over come buffering capacity of system; positive produces red color, (+) E. coli

Question 4

Voges Proskauer

Answer 4

determines ability to produce acetoin from fermentation of glucose; positive turns pink

Question 5

Citrate

Answer 5

determines ability to utilize sodium citrate as only carbon source and inorganic ammonium salts as only nitrogen source; positive produces growth on a medium with or without color change from green to blue; (+) K. pneumoniae

Question 6

Oxidase

Answer 6

determines presence of oxidase; positive turns dark purple; Enterobacteriaceae will never be positive; should not be performed from selective agars

Question 7

Cetrimide

Answer 7

determines ability of organism to grow in presence of Cetrimide, a toxid substance that inhibits growth of many bacteria; positive produces growth; (+) P. aeruginosa

Question 8

TSI (Triple Sugar Ion Agar)

Answer 8

determines production of glucose, lactose, and sucrose, and production of H2S (hydrogen sulfide; slant starts out light red; if H2S+, must be A/alkaline butt-cannot ferment H2S without glucose fermentation;

Question 9

LIA (Lysine Iron Agar)

Answer 9

determines fermentation of glucose, production of H2S, and deamination of lysine; slant starts out purple

Question 10

API 20E

Answer 10

identification system, saline mixed with organism is added to testing mixtures