BIOCHEMICAL REACTIONS Flashcards
Enterobacteriaceae are called what
enterics
what are the characteristics of colonies produced by Enterobacteriaceae in SBA and CHOC agar?
large, moist, gray colonies that can’t be distinguishable
Large mucoid colonies are caused by what type of bacteria/s
Klebsiella and Enterobacter
Beta hemolytic colonies are caused by what type of bacteria/s
Escherichia coli
What are the primary isolation media used for isolating enterics
MacConkey (MAC)
Eosin-Methylene Blue (EMB)
Hektoen enteric agar (HEA)
Salmonella Shigella Agar (SSA)
Xylose-Lysine-Deoxycholate (XLD)
This media can also be used to detect H2S production
Xylose-Lysine-Deoxycholate (XLD)
All are CYTOCHROME OXIDASE NEGATIVE, except for
Plesiomonas species
Most species are able to reduce nitrates to nitrites, except:
Erwinia and Pantoea agglomerans
what bacterias are non-motile at 37C and 25C
Klebsiella
Shigella species
Yersinia pestis
what bacterias are non-motile at 37C but motile
at 25C
Yersinia enterocolitica
Yersinia pseudotuberculosis
able to utilize carbohydrates OXIDATIVELY (aerobic utilization)
oxidizers
are unable to utilize carbohydrates even in the presence of oxygen (ASSACHAROLYTIC or NON-SACCHAROLYTIC)
non-oxidizers
what algorithm does enteric and non-fermentative bacteria follow for laboratory isolation and detection
Specimen Accesioning and Evaluation
Direct Microscopy
Inoculation to primary isolation media
what color of colony does lactose fermenter produce
pink
if the bacteria is a lactose fermenter and has a presence of encapsulated bacteria what color and type of colony is produced
Pink colonies and mucoid colonies
what color of colony does non-lactose fermenter produce
colorless colonies
INOCULATION:
- TSI
- LIA
- MR
- VP
- SIM
- Citrate
- Urease
A. TSI – stab and streak
B. LIA – stab, streak, and stab
C. MR – emulsify colonies using loop or needle
D. VP - emulsify colonies using loop or needle
E. SIM- stab
F. Citrate- streak
G. Urease - streak
orientation of TSI
butt/slant medium
CHO content of TSI
(0.1%) Glucose
(1%) Lactose and Sucrose
alternate source of energy in TSI
Peptone
pH indicator of TSI
Phenol red
source of sulfur for H2S production by bacteria (sulfur donor)
Sodium thiosulfate
indicator for H2S
Ferrous sulfate
TSI reaction of EKES
A/A, H2S-
TSI reaction of SPC
A/A, H2S +
TSI reaction of SPACEd
K/A, H2S+
TSI reaction of YES PM
K/A, H2S-
Principle pf LIA
Determine the ability of organisms to deaminate or decarboxylase lysine and produce H2S gas
TSI reaction of Non-fermentative organisms
K/K
bacterias that are deaminase +
Proteus
Providencia
Morganella
orientaion of LIA
slant/butt
serves as the substrate for the decarboxylase or deaminase enzyme of bacteria.
lysine
the fermentable sugar that provides acidity to the medium after fermentation by bacteria
1% Glucose
pH indicator of LIA
bromcresol purple
Principle of Methyl Red and Voges-Proskauer test
Glucose degradation in the Embden-Meyerhoff pathway produce pyruvic acid as byproduct.
products of MR and VP test
MR - mixed acids
VP - diacetyl
detects mixed acids produced from pyruvic acid after its further degradation by bacteria though the mixed acids pathway
methyl red test
detects diacetyl as a product of the oxidation of acetoin which is a byproduct produced from pyruvic acid after its further degradation by bacteria through the butylene glycol pathway.
VOGES-PROSKAUER TEST
neutral pathway produces that color
pink
acidic pathway produces that color
red
It is a semi-solid medium that facilitates bacterial motility
Sulfide Indole Motility (SIM) test
– enters the bacterial cell’s metabolic pathway for the production of energy
Pyruvate
pH indicator of CITRATE
Bromthymol blue
Principle of Urease test
Urease splits the urea molecule into NH3, CO2, and H2O. Ammonia reacts in the solution to form an
alkaline compound, ammonium carbonate, which results in an increased pH of the medium and a
color in the indicator to pink-red.
original color of urease
yellow
Principle of Citrate
Some organisms can utilize SODIUM CITRATE as their sole source of carbon producing acetate and other alkaline carbonate end products in the process. These product change the color of the indicator from green to blue.
SIM H2S indicator forming a black precipitate
ferrous ammonium sulfate
the only carbon source of CITRATE
Sodium citrate
pH indicator of urease
phenol red
RAPID UREASE PRODUCERS (w/in 2-4
hours)
Proteus
Providencia
Morganella
WEAK UREASE PRODUCERS within 4 hours
Citrobacter
Klebsiella
Enterobacter
Yersinia
Seratia
Used to study CHO utilization by non-fermenters.
Oxidation/Fermentation (OF) Test
Principle of Nitrate reduction test
Some organisms possess nitrate reductase that can reduce nitrate (NO3−) to nitrite (NO2−)
break down of gelatin to amino acid
Gelatin hydrolysis
What species are the only genera positive for Phenylalanine deaminase.
Proteus, Providencia, Morganella
what bacteria is present if the gelatin hydrolysis test is positive
Serratia species
pH indicator of OF test
Bromthymol blue
