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© 2012 AOAC INTERNATIONAL
(
c
)
Caution
: Dispose of all reagents and other contaminated
materials by acceptable procedures for potentially biohazardous
materials. All microbial cultures are potentially infectious and
should be treated with universal precautions.
(
d
) Store VITEK 2 GP cards at 2–8°C.
(
e
) Do not freeze test cards.
(
f
) Bring reagents to room temperature before inserting them
into the VITEK 2 instrument.
(
g
) Return unused cards to 2–8°C immediately after use.
Note
: A Gram stain should be performed to determine a pure
culture’s Gram reaction and morphology prior to selecting which
VITEK 2 identification card to inoculate. Interpretation of test
results requires the judgment and skill of a person proficient in
Gram staining and knowledgeable in the interpretation of the Gram
reaction and morphology of microorganisms.
D. Preparation of Test Suspension
(
a
) Aseptically transfer 3.0 mL sterile saline (aqueous 0.45 to
0.50% NaCl, pH 4.5–7.0) into polystyrene test tubes (12×75 mm).
Do not use glass tubes.
(
b
) Using a sterile stick or swab, transfer a sufficient number of
colonies from a 24 h culture on recommended culture medium to
the saline tube to achieve a density equivalent to McFarland 0.50 to
0.63 with the VITEK 2 DENSICHEK.
(
c
) Test the cultures by the VITEK 2 GP method within 30 min
of preparation of the suspended culture.
(
d
) Insert the culture tube and the VITEK 2 GP card into the
VITEK 2 cassette and refer to the User Manual (to be provided
with the instrument) for instructions on use of the instrument.
(
e
) Report identification results from the VITEK 2 system.
(
f
) As indicated in theVITEK 2 GPproduct information provided
to end-users, slashline or low discrimination identifications
are acceptable results for the VITEK 2 GP method that require
supplemental tests to further resolve the organism identification.
E. Results and Interpretation
The results are interpreted by the VITEK 2 system. Printed
results will indicate a high probability match to a single species
if a unique identification pattern is recognized. If a unique pattern
is not recognized, the system will suggest supplemental tests to
distinguish between two or three closely related organisms, or
indicate the result as an unidentified organism (either >3 organisms
can exhibit the observed pattern, or the biopattern is very atypical
and is not represented in the database). It is recommended that
hemolysis on blood agar is reviewed for any identification of
Listeria innocua.
If
b
-hemolysis is observed, further testing must
be performed to exclude
Listeria monocytogenes.
Reference:
J. AOAC Int. 95 , 1425(2012)Table 2012.02C. Biochemical tests included in the VITEK 2
GP card
Well
Test
Abbreviation
2
D-Amygdalin
AMY
4
Phosphatidylinositol phospholipase C PIPLC
5
D-Xylose
dXYL
8
Arginine dihydrolase 1
ADH1
9
b
-Galactosidase
BGAL
11
a
-Glucosidase
AGLU
13
Ala Phe Pro arylamidase
APPA
14
Cyclodextrin
CDEX
15
L-Aspartate arylamidase
AspA
16
b
-Galactopyranosidase
BGAR
17
a
-Mannosidase
AMAN
19
Phosphatase
PHOS
20
Leucine arylamidase
LeuA
23
L-Proline arylamidase
ProA
24
b
-Glucaronidase
BGURr
25
a
-Galactosidase
AGAL
26
L-Pyrrolidonyl-arylamidase
PyrA
27
b
-Glucaronidase
BGUR
28
Alanine arylamidase
AlaA
29
Tyrosine arylamidase
TyrA
30
D-Sorbitol
dSOR
31
Urease
URE
32
Polymixin B resistance
POLYB
37
D-Galactose
dGAL
38
D-Ribose
dRIB
39
L-Lactate alkalinization
ILATk
42
Lactose
LAC
44
N
-Acetyl-D-glucosamine
NAG
45
D-Maltose
dMAL
46
Bacitracin resistance
BACI
47
Novobiocin resistance
NOVO
50
Growth in 6.5% NaCl
NC6.5
52
D-Mannitol
dMAN
53
D-Mannose
dMNE
54
Methyl-B-D-glucopyranoside
MBdG
56
Pullulan
PUL
57
D-Raffinose
dRAF
58
O/129 Resistance (comp.vibrio.)
O129R
59
Salicin
SAL
60
Saccharose/sucrose
SAC
62
D-Trehalose
dTRE
63
Arginine dihydrolase 2
ADH2s
64
Optochin resistance
OPTO
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