media and reagents

Question 1

TSI ingredients

Answer 1

Triple sugar iron slant: glucose, lactose sucrose, sodium thiosulfate, peptone. phenol red is pH indicator

Question 2

TSI K/A H2S+ gas+ biochemical reaction indicates

Answer 2

K=glucose fermentation (occurs rapidly) turning slant yellow. Organism catabolizes aa producing NH3 making slant alkaline and red. Alkalinity will not overcome butt which remains yellow.
A=only glucose fermented
H2S thiosulfate reduced to H2S

Question 3

3 infamous lactose fermenting organisms

Answer 3

E. coli, K. pneumoniae, Enterobacter aerogenes

Question 4

3 common non lactose fermenting enterics

Answer 4

Salmonella, Shigella, Citrobacter, Proteus

Question 5

TSI A/A gas

Answer 5

A/A=glucose and lactose fermenter. Gas is a result of fermentation.

Question 6

TSI K/K

Answer 6

peptones catabolized aerobically and anaerobically.

Question 7

MIO:Motility indole ornithine

Answer 7

Motility: turbidity
Indole: James reagent (dimethylaminobenzealdehyde in HCl and amyl alcohol-alchohol concentrates color as ring at surface) detect indole (reacts with aldehyde to form red/pink) , a byproduct of tryptophan methabolism
Ornithine: ornithine decarboxylation – formation of a highly alkaline product, over-neutralizing the acid produced from glucose fermentation in bottom 3/4 of tube see faded purple.

Question 8

LIA: Lysine Iron Agar describe biochemical reaction

Answer 8

Ingredients: peptone, yeast, glucose, lysine bromcresol purple, thiosulfate
Lysine: lysine decarboxylation requires an anaerobic env & results in purple butt. deamination of lysine in slant results in redish color.
Iron: thiosulfate in electron receptor and if reduced becomes hydrogen sulfide.

Question 9

citrate

Answer 9

determines ability to use citrate as sole carbon source brought about by the enzyme citrase. AMmonium ion in sole nitrogen souce. Bromthymol blue is pH indicator. pH>7.6, BMB turns blue. Citrate utilization is an aerobic process, as Na2 CO3 accumulates and is an aerobic compound, the media is basic and truns BMB Prussian blue..

Question 10

enteric screen biochemicals

Answer 10

citrate, LIA, TSI, urea, MIO

Question 11

Urea test media

Answer 11

determines organisms ability to hydrolyze urea with urease. it contains phenol red, yellow,8.4 and red>8.4. Determines ability to convert urea to ammonia which is alkaline, raises pH and turns phenol red yellow to pink.

Question 12

urea test media useful in differentiating microbial causes of which pathogens

Answer 12

UTI pathogens from genus proteus and other enteric bacteria by rapid urease activity.

Question 13

3 organisms with rapid urease activity

Answer 13

proteus, morganella, providencia

Question 14

organisms with delayed urease positive organism

Answer 14

citrobacter, enterobacter, klebsiella. pink color in slant only indicateds delayed urease positive organism.

Question 15

imvic tests

Answer 15

four reactions to identify enterobacteriaceae: indole, methyl red, voges proskauer, citrate (I for rhymying)

Question 16

methyl red test in imvic reaction

Answer 16

detects an organisms ability to detect and maintain stable acid end products from glucose fermentation. methyl red is a ph indicator and is red at a ph of 4.4 or less. when added to broth with e. coli it turns red

Question 17

VP in IMViC tests

Answer 17

detects butylene glycol producers. KOH added to broth containing acetoin producinmg diacetyl which reacts with guanidine components of peptone to react with alpha-naphthol to produce red color. alpha is a catalyst and color intensifier

Question 18

citrate

Answer 18

detects organisms ability utilitize citrate as sole source of carbon. pH indicator is bromothymole blue. production of oxaloacetate and acetate as byproducts of citrate utilization results in alkaline pH changing media from blue to green

Question 19

positive and negative controls for IMViC tests

Answer 19

E. coli positive for I & , MR but negative for VP and citrate. K. pneumonia negative: indole, MR, but pos VP and citrate