F, Lab (biochemtest Gram- Bacilli) Flashcards
(23 cards)
determine whether a Gram-
negative rod ferments glucose and lactose or
sucrose and forms H2S
TRIPLE SUGAR IRON AGAR
TRIPLE SUGAR IRON AGAR composition
o 10 parts lactose:
o 10 parts sucrose:
o 1 part glucose and peptone.
serve as
indicators of acidification and HS
formation, respectively.
Phenol red and ferrous sulfate
This test is used to differentiate Gram-negative
bacilli based on decarboxylation or deamination
of lysine and the formation of hydrogen sulfide
(H2S).
LYSINE IRON AGAR
When glucose is fermented, the butt of the
medium becomes
acidic (yellow).
The combination test methylired (MR) and Voges-
Proskauer (VP) differentiates members of
Enterobacterales
METHYL RED AND VOGES-PROSKAUER TESTS
Methyl red positive
Bright red color, indicative of mixed acid
fermentation
Metyhl red weak positive
Red-orange color
Methyl red negative
Yellow color
VOGES-PROSKAUER TEST positive
Red
VOGES-PROSKAUER TEST negative
Yellow color
identify organisms
capable of using sodium citrate as the sole carbon
source and inorganic ammonium salts as the sole
nitrogen source.
SIMMON’S CITRATE AGAR
SIMMON’S CITRATE AGAR +
Growth on the medium, with or without a
change in the color of the indicator.
Growth on the medium, with or without a
change in the color of the indicator -
Absence of growth
this test is used to determine an organism’s ability
to produce the enzyme urease, which hydrolyzes
urea. Proteus spp. may be presumptively identified
by the ability to rapidly hydrolyze urea.
UREASE TEST
Urease +
Change in color of slant from light orange
to magenta
Urease -
No color change
These tests are used to determine whether an
enteric organism is motile. An organism must have
flagella to be motile.
SULFIDE-INDOLE-MOTILITY TEST
MOTILITY TEST
SULFIDE-INDOLE-MOTILITY TEST
MOTILITY TEST +
Motile organisms will spread out into the
medium from the site of inoculation.
SULFIDE-INDOLE-MOTILITY TEST
MOTILITY TEST -
Nonmotile organisms remain at the site of
inoculation.
This test is used to identify organisms that produce
the enzyme tryptophanase.
SIM – INDOLE PRODUCTION TEST
SIM – INDOLE PRODUCTION TEST +
Pink- to wine-colored ring after addition of
appropriate reagent
SIM – INDOLE PRODUCTION TEST -
No color change after addition of the
appropriate reagent
