Lab 17 Biochemical Differentiation Of Some Medically Important Gram Negative Bacilli

Front 1

what are members of the family Enterobacteriaceae found in the body

Back 1

intestines

Front 2

macConkey is a selective medium

Back 2

Because it inhibits gram positive bacteria growth
supports gram negative enteric bacilli

Front 3

macConkey is a differential medium because

Back 3

contagious the indicator neutral red which distinguishes whether bacteria ferment lactose or not

Front 4

coliform bacteria

Back 4

coliforms are nonpathogenic enterics that do not normally cause serious illness
presence on foods or water indicate pathogenic organisms of fecal origin may also be present

Front 5

nonpathogenic Gram negative bacilli on MacConkey agar

Back 5

deep pink colonies= lactose ferment (coliform)

Front 6

pathogenic gram negative enteric bacteria on MacConkey agar

Back 6

colorless colonies= lactose nonferment

Front 7

small inverted tube in glucose broth (gram negative bacilli)

Back 7

Durham tube, traps CO2 bubbles given off during glucose fermentation

Front 8

indicator in carb. ( glucose and fructose)

Back 8

phenol red ( deep red at>6.8, yellow. at <6.8)

Front 9

plus circled

Back 9

two tests glucose with Durham test tube and middle reading of TSI tube testing

it means acid production with gas

Front 10

acidic means phenol red

Back 10

yellow = positive

Front 11

3 carbs in TSI agar and percentage.

Back 11

.1 glucose 1 lactose 1 sucrose

Front 12

TSI aerobic/anaerobic

Back 12

slant aerobic/ butt anaerobic

Front 13

iron salts (ferrous sulfate) in TSI medium

Back 13

H2S hydrogen sulfide = black percipitate called ferric sulfide Fe2S3

Front 14

when recording TSI what do slashes mean

Back 14

fermentation of lactose/&or glucose in aerobic condition/
fermentation of glucose to produce gas in anaerobic condition
H2S production in aerobic condition (if black/+ assume glucose production +)

Front 15

IMViC

Back 15

Indole Methyl red Voges proskauer Citrate tests

Front 16

indole test

Back 16

if enzyme tryptophanase present (indicate presence of indole)

Front 17

added to inoculated and incubated indole medium

Back 17

Kovacs reagent

Front 18

phosphate buffer

Back 18

MR VP

Front 19

methyl red test indicator

Back 19

methly red
positive when do much acid over populate buffered system
added after incubation and is toxic
red= 4.4 positive
orange= 4.4 to 6 further incubation
yellow= 6 negative

Front 20

positive methyl red

Back 20

deep red ph <4.4

Front 21

reagent added to an inoculated and incubated Voges Proskauer test

Back 21

a naphthol (Barrets reagent a) 40 koh (Barritts reagent b)

Front 22

positive Vogues Proskauer

Back 22

aceton presence reddish color (methyl red pH <4.4)

Front 23

indicator in Citrate test

Back 23

bromthymol blue ( blue at pH >7.6)
positive bacterial growth: blue, pH >7.6, alkaline from breakdown of citrate, only vacteria with citrase can grow bc citrate is the only source of carbon

Front 24

citrate utilization test indicates whether or not the bacteria makes

Back 24

the enzyme citrase and thus can utilize the only carbon source available aerobically

Front 25

urease test indicates whether or not the bacterium makes

Back 25

the enzyme urease to break down urea. this forms ammonia (alkaline) raising the pH (phenol red) turning hot pink

Front 26

why is the motility medium a gel

Back 26

motile bacteria possessing flagella are able to move through the gel.

Front 27

how do you explain a negative test result that should be positive

Back 27

not inoculated
needle/loop too hot=dead microbes

Front 28

how to explain a positive result that should be negative

Back 28

contamination