Enterics Media And Biochemicals

Front 1

pathogens in stool?

Back 1

1.salmonella
2.shigella
3.yersinia
4.E. coli 0157:H7

Front 2

Typhoid fever (Enteric fever) is caused by which organism?

Back 2

Salmonella typhi

Front 3

Gram stain enterics?

Back 3

Gram negative bipolar staining a.k.a “Safety pin”

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Presumptive Identification of Enterobacteriaceae?

Back 4

1. Lrg gray, wet, mucoid on BAP
2. LF OR NLF on MAC
3.GNR “safety pin”, bipolar staining
4. Glucose fermenters
5. Oxidase negative
6 Nitrate positive
7.Catalase = positive
Exception: Shigella dysenteriae type I

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oxidase test detect the presence of ______?
positive result is ____?

Back 5

bacterial cytochrome oxidase
---tetramethyl-p-phenylenediamine dihydrochloride is oxidized to produce indophenol as an endproduct

positive result: purple

Front 6

selective agents of MAC?

Back 6

Bile salts and crystal violet
---Inhibits growth of g+ and g- cocci

Front 7

MAC interpretation?

Back 7

Pink colonies is Lactose fermenting gram negative rods

clear colonies is nonlactose fermenting gram negative rods

Late Lactose Fermenters=
Clear colonies @24hrs
Pink colonies @48hrs

Front 8

purpose of Levine’s Eosin-Methylene Blue (EMB)?

Back 8

Used to culture fecal (stool) specimens

Front 9

interpretation of EMB?

Back 9

Rapid LF= Blue/black colonies with green metallic sheen (i.e ESC)

Late LF = blue/purple colonies

NLF= clear, slightly amber colonies

Front 10

purpose of Xylose Lysine Desoxycholate-XLD?

Back 10

1.To selectively isolate and identify ONLY the stool pathogens
2.Used to culture fecal (stool) specimens

Front 11

selective agent of XLD?

Back 11

Sodium desoxycholate
----Inhibits gram + and gram - cocci

Front 12

pH indicator and H2S indicator of XLD?

Back 12

phenol red and Ferric ammonium citrate

Front 13

Xylose Lysine Desoxycholate agar (XLD)-Interpretation?

Back 13

LF(coliforms) =yellow

possible enteric pathogen:
NLF= clear or red
OR Clear colonies with H2S

Front 14

purpose of Hektoen-Enteric Agar (HE)?

Back 14

Used to selectively culture fecal specimens
Identify stool pathogens (Salmonella/Shigella)

Front 15

HE interpretation?

Back 15

Lactose Fermenter=
Orange/Salmon pink colonies = Normal Flora (NF) Any Carbohydrate fermentation

NLF=clear colonies
No carbohydrate
Fermentation=poss. Pathogen
Shigella

Clear colonies (CC)
with H2S+ black
?poss. Pathogen
Salmonella

Front 16

purpose of Gram Negative Broth(GN broth)?

Back 16

Promotes growth of Salmonella and Shigella from direct fecal specimens while inhibiting other bacteria

Front 17

the media used for the isolation of Y. enterocolitica
Can grow Aeromonas sp.?

Back 17

Cefsulodin Irgasan Novobiocin (CIN)

Front 18

Carbohydrate source of CIN?

Back 18

Mannitol
---utilized by Yersinia unlike other enterics

Front 19

CIN interpretation?

Back 19

Y.enterocolitica = Bull’s eye colonies
Mannitol fermenter = pink

Aeromonas = pink center
with clear border

Clear colonies = orgs. does not ferment mannitol

Front 20

purpose of MAC with Sorbitol (SMAC)?

Back 20

1. Used for the isolation and differentiation of sorbitol-neg E.coli. Esp. shiga-toxin-producing strains of E.coli 0157 from GI specimens.

Front 21

interpretation of SMAC?

Back 21

Pink colonies = not E.coli 0157

E.coli 0157 =clear colonies

Front 22

CHROMAGAR for____?

Back 22

Based on colored-specific colony(blue for ESC and mauve for ESC: 0157)

Front 23

purpose of Bismuth Sulfite agar?

Back 23

Used for the isolation of Salmonella and Shigella species

Black or Green colonies surrounded by black or brown zone
= possible Salmonella

Front 24

selenite F broth is an/a_____broth and used to isolate____and _____?

Back 24

Used for isolation of Salmonella and Shigella

Front 25

Potassium Cyanide broth(KCN)?

Back 25

Used to differentiate between Citrobacter freundii vs. Salmonella

Front 26

KCN-Interpretation?

Back 26

Positive
Turbidity in KCN + KCN free broth
R to KCN= klebsiella, proteus, C. freundii
Negative
Turbidity in KCN-free;no growth in KCN tube
S to KCN= E. coli, salmonella, and shigella

Front 27

lactose fermentation-Bacteria require which two enzymes to efficiently break down lactose bonds to glucose and galactose?

Back 27

beta-galactoside permease
beta-galactosidase

Front 28

purpose of Orthonitrophenyl- beta-D-galactopyranoside (ONPG)

Back 28

Differentiate between TRUE 1.differenciate NLF and late LF
2.Detects enzyme -galactosidase

Front 29

principle of ONPG?

Back 29

1.ONPG is cleaved into galactose and orthonitrophenol
in the presence of beta-galactosidase

Front 30

interpretation of ONPG?

Back 30

positive-yellow
negative-colorless

Front 31

the purpose and principle of Nitrate reduction test?

Back 31

Purpose
Detects org. that possess nitrate reductase

Principle
(1) to detect Nitrate reduction to nitrates
(2) to detect nitrate reduction to gas

Front 32

Nitrate Reduction test interpretation?

Back 32

positive:
1.red after rgts added
2.colorless after zinc is added

negative:
1. red after zinc is added

Front 33

principle of indole production?

Back 33

Used to detect the production of indole, by-product of tryptophan degradation

Front 34

when doing the indole spot test, is it correct that colony MUST BE TAKEN from BAP and CHOC?

Back 34

correct, because these two media contain tryptophan

Front 35

interpretation of indole rapid spot test?

Back 35

positive-blue
negative-colorless

Front 36

purpose of Methyl Red test (MR)?

Back 36

To detect organisms that utilize the mixed acids pathway to break-down pyruvate (pyruvic acid)

Front 37

interpretation of MR?

Back 37

P = Positive = Red color
N = Negative = No color

Front 38

purpose of Voges-Proskauer test (VP)?

Back 38

Detect acetoin produced from the break-down of pyruvate using the butanediol pathway
VP + orgs. = Klebsiella, Enterobacter, Serratia

Front 39

principle of Voges-Proskauer test (VP)?

Back 39

Butanediol is broken down into acetoin and butylene glycol
Acetoin is detected using 40% KOH and alpha-naphthol to form a red colored complex

Front 40

is that correct that enterics are MR or VP pos but never both?

Back 40

correct

Front 41

purpose of Phenylalanine Deaminase (PAD)?

Back 41

To detect organisms that possess PAD
PAD+ : Proteus, Morganella, Providencia

Front 42

interpretation of Phenylalanine Deaminase (PAD) ?

Back 42

Pos = green
Neg = no color change (Yellow)

Front 43

purpose of Triple Sugar Iron (TSI) agar?

Back 43

Used to differentiate GNR based on carbohydrate fermentation and H2S production

Front 44

what are 3 sugars in TSI?

Back 44

Glucose (1g/L), lactose(10g/L), sucrose(10g/L)

Front 45

TSI-Interpretation
K/K or K/NC (red/red)

Back 45

1.No carbohydrate fermented = no acid formed
2. Org. uses peptones, produces alk. end-products
3.Org. is NOT an enteric
OR media is uninoculated

Front 46

TSI -interpretation
K/A (Red/yellow) ?

Back 46

Glucose is fermented anaerobically
Lactose + sucrose are NOT fermented

Front 47

TSI interpretation
K/A H2S (Red/yellow with black butt)?

Back 47

Glucose is fermented
Lactose and sucrose are NOT fermented (NLF)
Always report butt as acid b/c H2S is only produced in an acidic environment

Front 48

the difference between TSI and KIA (Kliger Iron Agar )?

Back 48

TSI = Glucose, lactose, and sucrose
KIA = Glucose and lactose only

Front 49

purpose of Lysine Iron agar (LIA)

Back 49

1.Used to screen isolates from stool for enteric pathogens
2.Detect the presence of lysine decarboxyalse or lysine deaminase

Front 50

principle of LIA?

Back 50

Determines if an org decarboxylates or deaminates lysine and forms H2S

Front 51

LIA interpertation?

Back 51

1.Facts-Uninoculated Media is Purple
2.Slant portion is aerobic (Needs O2;LOOSE CAP!!)
Butt/deep is anaerobic(glucose fermentation)
2.Yellow = Carbohydrate fermentation
Glucose is utilized first
3.Red = Lysine Deamination (usu. Top 1/2 of media)
4.Purple = Lysine Decarboxylation takes place in the butt
5. Black = H2S production in butt
Requires an acidic environment

Front 52

Motility-Indole-Lysine-Sulfide (MILS)?

Back 52

To detect
1.Motility
2.Lysine utilization (decarboxylation vs. deamination)
3.Indole production
4. H2S production

Front 53

MILS interpretation?
motility

Back 53

Glucose must be utilized for test validity=yellow butt
Motility
Pos = growth extends away from stab line
NEG = growth occurs only along stab line

Front 54

MILS interpreation-Lysine Decarboxylation (READ in bottom ½)?

Back 54

POS = Dark purple throughout medium
NEG = Yellow throughout OR may have a band of purple on top or no change in color

Front 55

MILS interpretation-Lysine Deamination (Read in TOP 1/2)

Back 55

POS = Deep RED surface in top portion of tube with yellow butt
NEG = may have purple band in top portion of medium with YELLOW butt

Front 56

MILS interpretation--H2S production and indole producton?

Back 56

H2S Production
POS = black precipitate
NEG = no precipitate
Indole
Add 3 drops of KOVAC’s:
POS = pink/Red @ surface
NEG No color change after KOVAC’s addition
NOTE: ALWAYS perform Indole detection LAST!!!

Front 57

purpose of Citrate Utilization?

Back 57

Used to determine if org. can utilize citrate as only carbon source, producing alkaline end-products

Front 58

interpretation of citrate utilization?

Back 58

A = Pos= Blue
B = Neg = green/no color change

Front 59

principle of urease test?

Back 59

To detect org. that possess urease. Urease break down urea to NH3
Principle
If org. contain urease, urea is broken down
NH3 production(alkaline) is detected

Front 60

interpretation of urease test?

Back 60

positive-hot pink
negative-colorless

Front 61

the principle of Amino Acid decarboxylase/dihydrolase?

Back 61

1. Lysine decarboxylase convert lysine to cadaverine

2. Ornithine decarboxylase convert ornithine to putrescine

3.dihydrolase convert arginine to citruline/ornithine and decarboxylase convert citruline/ornithine to putrescine

Front 62

purpose of AA decarboxylase/dihydrolase?

Back 62

Detects presence of decarboxylase enzymes that break down Lysine, Ornithine, or Arginine

Front 63

Amino Acid decarboxylase/dihydrolase results?

Back 63

Step 1
Org. ferment glucose = both tubes are yellow
Step 2
If org. has enzyme:
Amino acid is broken down to form amines
Amino acid tube = purple
Base media stays yellow