Part of Thermo Fisher Scientific
GRAM-NEGATIVE IDENTIFICATION SYSTEM
MICROBACT™ 12A (12E) AND 24E (12A (12E) + 12B)
GRAM-NEGATIVE IDENTIFICATION SYSTEM
CODES: MB1073, MB1074, MB1076, MB1077, MB1130, MB1131, MB1132, MB1133.
Intended use
The Microbact™ Gram-negative system is to be used for the identification of
aerobic and facultatively anaerobic Gram-negative bacteria (Enterobacteriaceae
and miscellaneous Gram- negative bacteria) 2,3,4,5,6,7.
Principle of the test
The Microbact™ Gram-negative system is a standardised micro-substrate system
designed to simulate conventional biochemical substrates used for the identification
of Enterobacteriaceae and common miscellaneous Gram-negative bacilli (MGNB).
Organism identification is based on pH change and substrate utilisations
as established by published reference methodologies 4,6,8,9. Refer
to the Table of Reactions below for the substrates contained in each well,
the specific
reaction principle, and colour changes.
The Microbact™ Gram-negative product
consists of two separate substrate strips, 12A and 12B. Each strip consists
of 12 different biochemical substrates. The
12A strip may be used alone for identification of oxidase-negative, nitrate-positive
glucose fermenters comprising 15 genera and may be useful for screening pathogenic
Enterobacteriaceae from enteric and urine specimens or identification of other
common isolates. The 12B strip can be used in conjunction with the 12A strip
for the identification of oxidase-positive, nitrate-negative, and glucose-nonfermenters
(MGNB) as well as the Enterobacteriaceae.
Note: The 12 substrates contained in
the 12A strips are available in a solid microplate format, referred to as 12E.
The 12B strips can be used alongside
the 12E, but in a separate tray. The 24E solid microplate format contains the
24 substrates contained in the combination of both the 12A and 12B strips.
THE FOLLOWING SPECIES OF OXIDASE-NEGATIVE, GRAM-NEGATIVE BACILLI CAN BE IDENTIFIED
USING THE 12A (12E) ALONE:
Enterobacteriacea
Acinetobacter spp. | Shigella spp. | P. stuartii |
A. baumannii | Shigella serogp. AB&C |
P. alcalifaciens |
A.lwoffii | S. sonnei | Salmonella spp. |
A. haemolyticus | Hafnia sp. | Salmonella spp. |
Citrobacter spp. | H. alvei | S. typhi |
C. freundii | Klebsiella spp. | S. cholerae-suis |
C. diversus |
K. pneumoniae | S. paratyphi A |
Enterobacter spp. | K. oxytoca |
S. arizonae |
E. aerogenes | K. ozaenae | Serratia spp. |
E. cloacae | K. rhinoscleromatis | S. marcescens |
E. agglomerans | Morganella sp. | S. liquefaciens |
E. gergoviae | M. morganii | S. rubidaea |
E. sakazakii |
Proteus spp. | Tatumella sp. |
Escherichia spp. | P. mirabilis | T. ptyseos |
E. coli | P. vulgaris | Yersinia spp. |
E. coli-inactive | Providencia spp. | Y. enterocolitica |
E. vulneris | P. rettgeri | Y. pseudotuberculosis |
ADDITIONAL OXOIDASE-NEGATIVE, GRAM-NEGATIVE BACILLI CAN BE IDENTIFIED USING THE 12A (12E) + 12B COMBINED OR BY USING 24E:
Acinetobacter spp. | Ewingella sp. |
Salmonella subsp.3B |
A. baumannii | E. americana | Salmonella subsp.4 |
A. lwoffii | Hafnia sp. | Salmonella subsp.5 |
A. haemolyticus | H. alvei | Salmonella subsp.6 |
Budvicia sp. | H. alvei biogp 1 | Serratia spp. |
B. aquatica | Klebsiella spp. | S. marcescens |
Buttiauxella sp. |
K. pneumoniae | S. marcescens biogp 1 |
B. agrestis | K. oxytoca | S. liquefaciens |
Cedecea spp. | K. ornithinolytica | S. rubidaea |
C. davisae | K. planticola | S. odorifera biogp 1 |
C. lapagei | K. ozaenae | S. odorifera biogp 2 |
C. neteri | K. rhinoscleromatis | S. plymuthica |
Cedecea sp 3 |
K. terrigena | S. ficaria |
Cedecea sp 5 | Klebsiella gp 47 | S. entomophila |
Citrobacter spp. | K. ascorbata | S. fonticola |
C. freundii | K. cryocrescens |
Shigella spp. |
C. diversus | Leclercia sp. |
Shigella serogp.AB&C |
C. amalonaticus | L. adecarboxylata | S. sonnei |
C. amalonaticus biogp 1 | Leminorella spp. |
Trabulsiella sp. |
C. farmeri | L. grimontii | T.guamensis |
C. youngae |
L. richardii | Xenorhabdus spp. |
C. braakii | Moellerella sp. |
X. luminescens(25C) |
C.werkmanii | M. wisconsensis | X. luminescens gp 5 |
C. sedlakii | Morganella sp. |
X. nematophilis (25C) |
Citrobacter sp 9 | M. morganii | Xanthomonas sp. |
Citrobacter sp 10 | M. morganii ssp. morganii | X. (S. )maltophilia |
Citrobacter sp 11 | M. morganii biogp 1 | Yersinia spp. |
Edwardsiella spp. |
M. morganii ssp. Siboni 1 | Y. enterocolitica |
E. tarda | Obesumbacterium sp. |
Y. frederiksenii |
E. tarda biogp 1 | O. proteus biogp 2 | Y. intermedia |
E. hoshinae | Pragia sp. |
Y. kristensenii |
E .ictaluri | P.fontium | Y. rohdei |
Enterobacter spp. | Proteus spp. |
Y. aldovae |
E. aerogenes | P. mirabilis | Y. bercovieri |
E. cloacae |
P. vulgaris | Y. mollaretii |
E. agglomerans | P. penneri | Y. pestis |
E. gergoviae | P. myxofaciens | Y. pseudotuberculosis |
E. sakazakii | Providencia spp. | Y. ruckeri |
E. taylorae | P. rettgeri | Yokenella sp. |
E. amnigenus biogp 1 | P. stuartii | Y. regensburgei |
E. amnigenus biogp 2 | P. alcalifaciens | Enteric Gp17 |
E. asburiae | P. rustigianii | Enteric Gp41 |
E. hormaechei | P. heimbachae | Enteric Gp45 |
E. intermedium |
Rahnella sp. | Enteric Gp58 |
E. cancerogenus | R. aquatilis | Enteric Gp59 |
E. dissolvens | Salmonella spp. | Enteric Gp60 |
E. nimipressuralis | Salmonella subsp.1 | Enteric Gp63 |
Escherichia spp. | S. typhi | Enteric Gp64 |
E. coli | S. cholerae-suis | Enteric Gp68 |
E. coli-inactive | S. paratyphi A | Enteric Gp69 |
E. fergusonii | S. gallinarum | |
E. hermannii | S. pullorum | |
E. vulneris | Salmonella subsp.2 | |
E. blattae |
S. arizonae subsp.3A |
For further information refer to the Help File in the Microbact™ Computer Aided Identification Package.
AND THE FOLLOWING OXIDASE-POSITIVE BACTERIA CAN BE IDENTIFIED USING THE 12A (12E) + 12B COMBINED OR BY USING 24E:
Pseudomonas spp. | Flavobacterium spp. | Moraxella spp. |
Ps. aeruginosa | F. meningosepticum |
Moraxella spp. |
Ps. fluorescens-25 | F. odoratum (Myroides odoratus) | Plesiomonas sp. |
Ps. fluorescens-35 | F. breve (Empedobacter brevis) | P. shigelloides |
Ps. putida | F. indologenes (Chryseobacterium indologenes) |
Aeromonas spp. |
Ps. stutzeri | Vibrio spp. | A. hydrophila |
Ps. diminuta | V. fluvialis |
A. veronii bio sobria |
Burkholderia spp. | V. furnissii | A. veronii bio veronii |
B. cepacia | V. mimicus | A. caviae |
B. pseudomallei | V. vulnificus | Weeksella spp. |
Shewanella sp. | V. hollisae | W .virosa |
S. putrefaciens |
V. cholerae | W. zoohelcum |
Alcaligenes spp. | V. parahaemolyticus | Pasteurella spp. |
A. faecalis type 11 | V. alginolyticus | P. multocida |
A. faecalis | P. haemolytica | |
A. xylosoxidans spp. xylos |
Actinobacillus spp. | |
Actinobacillus sp. |
For further information refer to the Help File in the Microbact™ Computer Aided Identification Package.
Warning and precautions
1. These strips are intended for in vitro use only; for use by qualified laboratory
personnel using aseptic techniques and established precautions against microbiological
hazards.
2. Used materials should be autoclaved, incinerated, or immersed in germicide
before disposal.
3. DO NOT incubate strips in a CO2 incubator as substrates and/or enzyme reactions
could be adversely affected, giving false reactions.
Storage instructions
The test strips are stable if kept unopened in the foil envelopes until the
expiry date specified when stored at 2-8°C. Once the foil pouch has been
opened, unused strips must be placed back in the foil pouch, and the foil
pouch taped closed. Strips stored in this manner must be used within 7 days.
Kit presentation
Each kit contains the following:
1 Holding Tray.
Technical Product Insert.
Organism ID Report Forms including Colour Interpretation Chart.
Small Kits |
|
MB1130A Microbact 12E (10 pouches, 80 identifications) |
|
MB1131A Microbact 24E (10 pouches, 40 identifications) |
|
MB1132A Microbact 12A (10 pouches, 60 identifications) |
|
MB1133A Microbact 12B (10 pouches, 60 identifications) |
|
Large Kits |
|
MB1073A Microbact 12E (20 pouches, 160
identifications) |
|
MB1074A Microbact 24E (20 pouches, 80 identifications) |
|
MB1076A Microbact 12A (20 pouches, 120 identifications) |
|
MB1077A Microbact 12B (20 pouches, 120 identifications) |
Materials Required but not provided
The following materials may be required but are not provided:
Order Code | Product Name |
MB0209 | Indole |
MB0181 | VP I |
MB0184 | VP II |
MB0180 | TDA |
MB0186 | NIT A |
MB0187 | NIT B |
MB1093 | Mineral Oil |
MB0266 |
Oxidase Strips |
These can be purchased individually or as a set by ordering product code
MB1082:
Reagent Set D (Indole, VPI, VPII, TDA, NIT A/B)
MB1244 Microbact™ Computer
Aided Identification Package
MB0266A Oxidase reagent
Motility medium
2.5/5.0ml suitable saline solution, 0.85%
5.0ml peptone water (for use with selective media)
SR0035 Sterile serum
Zinc powder
Inoculating loop
Sterile pipettes
Fanless Incubator (or use container in Incubator with fan) (35° ± 2°C),
Non - CO2
Set up proceedure
Isolation
An 18-24 hour pure culture of the organism to be identified must be obtained.
Appropriate agar media, for example MacConkey (CM0007), Eosin Methylene Blue
(CM0069), Blood or Chocolate (CM0331 and SR0050), may be used to grow organisms.
Qualified
Personnel should collect specimens according to standards routinely required
for specimen handling 10.
Before use, perform an oxidase test on the
organism to be identified.
Note: Oxidase positive organisms cannot be identified
using the Microbact™ 12A (12E) alone and should be examined with the Microbact™ 24E
(12A (12E) + 12B).
Refer to the procedure chart for a condensed version of the
following procedures.
Procedure chart:
12A (or 12E) Enterobacteriaceae |
24E (12A (or 12E) + 12B) Enterobacteriaceae |
24E (12A (or 12E) + 12B) Miscellaneous Gram-Negative Bacilli |
|||||||||||||||||||||||||
Oxidase | Negative |
Negative |
Positive |
||||||||||||||||||||||||
Preparation of Inoculum | 1-2 colonies |
2-3 colonies |
2-3 colonies |
When Actinobacillus or Pasteurella spp. are suspected,
add 1 drop sterile serum per ml of saline suspension |
|||||||||||||||||||||||
Strip Inoculation | 4 drops to each well |
4 drops to each well |
4 drops
to each well |
||||||||||||||||||||||||
Oil Overlay | Well 1(lysine) Well 2 (ornithine) Well 3 (H2S) |
12B well 8 (arabinose) 24E well 20(arabinose) 12B well 12 (arginine) 24E well 24 (arginine) |
12B well 12 (arginine) 24E well 24 (arginine) |
||||||||||||||||||||||||
Incubation Temperature | 35° ± 2°C |
35° ± 2°C |
35° ± 2°C (25°C for Ps. fluorescens) |
||||||||||||||||||||||||
Test Reading: Read and record all positive test results |
Reagent Addition: Well 8 – Indole = 2 drops Kovacs, read within 2 minutes Well 10 – VP = 1 drop of each, VPI and VPII, read at 15 – 30 minutes Well 12 – TDA = 1 drop TDA, read immediately |
Reagent Addition: |
Reagent Addition: See 12A/12E Well 1 (12B) Well 13 (24E) Interpret Gelatin at 48 hours Well 12 (12B) Well 24 (24E) Arginine Yellow-green - Negative Blue - Positive |
Preparation of inoculum
Pick 1-3 isolated colonies from an 18-24 hour culture and emulsify in 2.5ml
of sterile saline solution if 12A/E alone is being used or 5.0 ml of sterile
saline if 24E (12A/E and 12B) are being used. Mix thoroughly to prepare a
homogeneous suspension.
If the organism has been grown on a selective medium and
the colony is small or inhibited, it may be necessary to emulsify the colony
in 5.0 ml of peptone
water and incubate at 35° ± 2°C for four hours. Using a sterile
Pasteur pipette, transfer one drop of the peptone water culture into the appropriate
volume (see Procedure Chart) of sterile saline solution (0.85%).
Inoculation
The wells of individual substrate sets can be exposed by cutting the end tag
of the sealing strip and slowly peeling it back.
Place the strip or plate in the
holding tray and using a sterile Pasteur pipette add 4 drops (approximately
100 µl) of the bacterial suspension, or half
fill each well in the set. When Actinobacillus or Pasteurella sp.
are suspected (no growth on media containing bile salts or on media deficient
in blood or
serum) add one drop of sterile serum (SR0035) per ml of saline suspension.
Using
a sterile pipette or dropper bottle, overlay the substrates underlined on the
holding tray with sterile mineral oil, i.e. wells 1, 2 and 3 for 12A
(12E) or 24E and wells 8 and 12 for 12B or wells 20 and 24 for 24E. (Well 8
for 12B and 20 for 24E is not overlayed with oil for oxidase- positive, miscellaneous
Gram-negative bacilli.)
Incubation
Reseal the inoculated rows with the adhesive seal and write the specimen identification
number on the end tag with a marker pen. Incubate at 35° ± 2°C
for 18-24 hours. When Ps. fluorescens appears as the organism of choice,
repeat the test at an incubation temperature of 25° ± 2°C.To determine
the purity of the inoculum, it is advisable to inoculate a solid non-selective
medium with the test suspension to act as a culture purity check.
Reading the test strip
1. The 12A (12E) strip should be read at 18-24 hours. The 12B/24E strip is
read at 24 hours when identifying Enterobacteriaceae. All systems should
be read after 48 hours for the identification of Miscellaneous Gram-negative
bacilli.
2. Remove the strips or tray from the incubator, peel back the sealing tape.
Record all positive results. The reactions are evaluated as positive or negative
by comparing them with the colour chart. Record the results under the appropriate
heading on the report form. For aid in interpreting reactions, refer to the
Table of Reactions.
1. 12A (12E) or 24E
Add the following reagents: Well 8 (Indole production) - add 2 drops of Indole
(Kovacs) reagent. Evaluate
within 2 minutes of the addition of the reagent.
Well 10 (Voges-Proskaüer
reaction) - add 1 drop each of VPI reagent and VPII reagent. Evaluate 15 to 30
minutes after the addition of reagents.
Well 12 (Tryptophan Deaminase) - add 1
drop of TDA reagent. Test can be evaluated immediately after the addition of
the reagent.
2. 12B/24E
The gelatin well (well 1 for 12B and well 13 for 24E) must be read at 24-48
hours for Enterobacteriaceae and at 48 hours for miscellaneous Gram-negative
bacilli (MGNB). Hydrolysis of gelatin is indicated by dispersal of the black
particles throughout the well.
The arginine reaction (well 12 for 12B and well
24 of 24E) is interpreted differently at 24 hours and 48 hours incubation.
24 Hours Incubation (Enterobacteriaceae):
Yellow - Negative
Green-blue - Positive
48 Hours Incubation (MGNB):
Yellow-green - Negative
Blue - Positive
Additional Test
Nitrate Reduction Test (o-nitrophenyl-ß-d-galactopyranoside (ONPG))
This test is performed in well 7 (ONPG) AFTER reading the ONPG reaction. One
drop of Nitrate reagent A and 1 drop of Nitrate reagent B is added to the well.
Production of a red colour within a few minutes of the addition of the reagent
indicates that nitrate reduction to nitrite (NO2) has occurred. A small amount
of zinc powder should be added to those wells which exhibit a yellow colour
after the addition of the nitrate reagents. This will determine whether nitrate
has been reduced completely to nitrogen gas (N2). The results should be interpreted
as follows:
After the addition of Nitrate reagents A and B: |
||
Red colour |
Positive |
NO2 Positive |
Yellow colour |
Negative |
NO2 Negative |
On the addition of zinc powder: |
||
Yellow colour |
Positive |
(N2+) |
Red colour |
Negative |
(N2-) |
All organisms belonging to the family Enterobacteriaceae reduce nitrates
to nitrites and give a positive reaction.
Note: Gram-negative bacilli which do not reduce nitrates can only be identified
by utilising the 24E (12A (12E) + 12B) system.
TABLE OF SUBSTRATES AND REACTIONS (12A/12E/24E):
Well No. | Designation |
Reaction Principle |
Reaction colours |
Comments |
|
Negative |
Positive |
||||
1 |
Lysine |
Lysine decarboxylase |
Yellow |
Blue-green |
Green or blue is positive reaction. Bromothymol blue
indicates formation of the specific amine cadaverine. |
2 |
Ornithine |
Ornithine decarboxylase |
Yellow-green |
Blue |
Green should be regarded as a negative reaction.
The pH shift indicated by bromothymol blue caused by formation of the
specific amine putrescine is greater than that caused by lysine decarboxylation. |
3 |
H2S |
H2S production |
Straw colour |
Black |
H2S is produced from thiosulphate. H2S reacts with
ferric salts in the medium to form a black precipitate. |
4 |
Glucose |
Glucose fermentation |
Blue-green |
Yellow |
Bromothymol blue indicator changes from blue to yellow when the carbohydrate is utilised to form acid. |
5 |
Mannitol |
Mannitol fermentation |
Blue-green |
Yellow |
|
6 |
Xylose |
Xylose fermentation |
Blue-green |
Yellow |
|
7 |
ONPG |
Hydrolysis of o-nitrophenyl-ß-d-galactopyranoside (ONPG)by action of ß-galactosidase |
Colourless |
Yellow |
ß-galactosidase hydrolysis of the colourless
ONPG releases yellow orth-onitrophenol. |
8 |
Indole |
Indole production from tryptophan |
Colourless |
Pink-red |
Indole is formed from metabolism of tryptophan.. Indole Kovacs reagent forms a pink-red complex with indole. |
9 |
Urease |
Urea hydrolysis |
Straw colour |
Pink-red |
Ammonium released from splitting of urea causes the
pH to rise - indicated by phenol red changing from yellow to pink-red |
10 |
VP |
Acetoin production (Voges-Proskaüer reaction) |
Straw colour |
Pink-red |
Acetoin is produced from glucose indicated by the
formation of a pink-red complex after the addition of alpha-naphthol
and creatine. |
11 |
Citrate |
Citrate utilization (citrate is the only source of carbon) |
Green |
Blue |
Citrate is the sole carbon source, which if utilized
results in a pH rise, indicated by bromothymol blue, with a colour change
from green to blue. |
12 |
TDA |
Production of indolepyruvate by deamination of tryptophan |
Straw colour |
Cherry red |
Tryptophan deaminase forms indolepyruvic acid from tryptophan which produces a brown colour in the presence of ferric ions. Indole positive organisms may produce a brown colour. This is a negative reaction. |
TABLE OF SUBSTRATES AND REACTIONS (12B/24E):
Well No. 12B/24E. |
Designation |
Reaction Principle |
Reaction colours |
Comments |
|
Negative |
Positive |
||||
1/13 |
Gelatin |
Gelatin liquefaction |
Colourless |
Black |
Liquefaction of gelatin by proteolytic enzymes diffuses the black pigment.
Solid gelatin particles which may drift across the well after rehydration
should
be considered as a negative reaction. |
2/14 |
Malonate |
Malonate inhibition |
Green |
Blue |
Sodium malonate is the sole carbon source and this
inhibits the conversion of succinic acid to fumaric acid. An organism
unable to utilize this substrate
results in the accumulation of succinic acid and the organism cannot
grow. Bromothymol blue is the indicator. Yellow-green is indicative of
a negative result. Utilisation of Na malonate at the same time that ammonium
sulphate is utilised
as the nitrogen source produces
sodium hydroxide resulting in increased alkalinity and a blue colouration. |
3/15 |
Inositol |
Inositol fermentation |
Blue-green |
Yellow |
Bromothymol blue indicator changes from blue to yellow when the carbohydrate is fermented. |
4/16 |
Sorbitol |
Sorbitol fermentation |
Blue-green |
Yellow |
|
5/17 |
Rhamnose |
Rhamnose fermentation |
Blue-green |
Yellow |
|
6/18 |
Sucrose |
Sucrose fermentation |
Blue-green |
Yellow |
|
7/19 |
Lactose |
Lactose fermentation |
Blue-green |
Yellow |
|
8/20 |
Arabinose |
Arabinose fermentation |
Blue-green |
Yellow |
|
9/21 |
Adonitol |
Adonitol fermentation |
Blue-green |
Yellow |
|
10/22 |
Raffinose |
Raffinose fermentation |
Blue-green |
Yellow |
|
11/23 |
Salicin |
Salicin fermentation |
Blue-green |
Yellow |
|
12/24 |
Arginine |
Arginine dihydrolase |
Argine dihydrolase converts arginine into ornithine, ammonia and carbon dioxide. This causes a pH rise as indicated by bromothymol blue. Green reactions occurring at 48 hours should be interpreted as negative |
||
24 hours |
Yellow |
Green-blue |
|||
48 hours |
Yellow-green |
Blue |
Interpretation
An octal coding system has been adopted for Microbact™ 1.
Each group of three reactions produces a single digit of the code. Using the
results
obtained,
the indices of the positive reactions are circled. The sum of these indices
in each group of three reactions forms the code number. This code is entered
into the computer package.
Computer aided identification Package
The Microbact™ Computer Aided Identification Package should be consulted for
the identification choices. The percentage figure shown against the organism
name is the percentage share of the probability for that organism as a part
of the total probabilities for all choices.
Note: Miscellaneous Gram-negative bacilli - Weakly positive reactions are recorded
as negative results. The results of tests for oxidase, nitrate reduction and
motility are included as part of the reaction pattern. Using the results obtained,
from each group of three reactions a 9 (nine) digit code number is produced.
Quality control
The overall performance of the system should be monitored by testing appropriate
control strains. The following organisms are recommended for independent
laboratory assessment.
Proteus mirabilis ATCC® 12453 | Escherichia coli ATCC® 25922 |
Klebsiella pneumoniae ATCC® 13883 | Acinetobacter baumannii ATCC®19606 |
The following chart gives the expected results on the Microbact System after an 18-24 hour incubation:
Escherichia coli ATCC® 25922 |
Klebsiella pneumoniae ATCC® 13883 |
Proteus mirabilis ATCC® 12453 |
Acinetobacter baumannii ATCC®19606 |
|||
1 |
12E/A 24E |
LYS |
+ |
+ |
- |
- |
2 |
ORN |
+ |
- |
+ |
- |
|
3 |
H2S |
- |
- |
+ |
- |
|
4 |
GLU |
+ |
+ |
+ |
+ |
|
5 |
MAN |
+ |
+ |
- |
- |
|
6 |
XYL |
+ |
+ |
- |
+ |
|
7 |
ONP |
+ |
+ |
- |
- |
|
8 |
IDN |
+ |
- |
- |
- |
|
9 |
URE |
- |
+ |
+ |
- |
|
10 |
VP |
- |
+ |
- |
- |
|
11 |
CIT |
- |
+ |
+ |
+ |
|
12 |
TDA |
- |
- |
+ |
- |
|
7 |
NIT |
+ |
+ |
- |
- |
|
1 |
24E/ 12B |
GEL |
- |
- |
- |
- |
2 |
MAL |
- |
+ |
- |
+ |
|
3 |
INO |
- |
+ |
- |
- |
|
4 |
SOR |
+ |
+ |
- |
- |
|
5 |
RHA |
+ |
+ |
- |
- |
|
6 |
SUC |
- |
+ |
- |
- |
|
7 |
LAC |
+ |
+ |
- |
- |
|
8 |
ARA |
+ |
+ |
- |
+ |
|
9 |
ADO |
- |
+ |
- |
- |
|
10 |
RAF |
- |
+ |
- |
- |
|
11 |
SAL |
- |
+ |
- |
- |
|
12 |
ARG |
- |
- |
- |
- |
Note 1: Serratia marcescens (ATCC® 43861) can be run as supplemental
QC to test the sensitivity of the GEL reaction. The expected results is positive.
Note 2: Flavobacterium multivorum (ATCC® 35656) may be used to show a negative
glucose result.
Limitations
1. Some bacterial strains may have atypical biochemical reactions due to unusual
nutritional requirements or mutations and may be difficult to identify.
2. Reactions obtained using the Microbact System may differ from published
results using other substrate formulations. Prolonged incubation, insufficient
incubation, improper filling of wells, or inadequate inoculum may lead to false
results.
3. Species with low frequency of occurrence require additional testing.
4. Acinetobacter calcoaceticus var. anitratus will include those strains that
have been designated as Acinetobacter calcoaceticus, Acinetobacter baumannii, and unnamed genospecies
3; most clinical isolates that are glucose-positive and nonhemolytic are Acinetobacter
baumannii.
5. The interpretation of mathematically calculated identification results requires
trained clinical personnel who should use judgement and knowledge in conjunction
with the following information before accepting the ID of an organism: Gram-stain,
colonial morphology, source of isolate, percent probability (degree of separation),
tests against, additional test indications and results, frequency of ID choice
and antibioGram.
6. A Gram-stain and oxidase test should be performed prior to set-up of tests.
In addition, motility and nitrate test should be performed for miscellaneous
Gram-negative bacilli.
7. When using the 12E/A strip alone, Klebsiella spp., Enterobacter spp.
and Serratia spp. should be reported as Klebsiella/Enterobacter/Serratia
group. Twelve substrates provide insufficient data to speciate within this
group as a single aberrant
reaction may result in an incorrect identification. The lysine and ornithine
decarboxylase reactions should be carefully interpreted. Motility and DNase
tests are recommended for further speciation of this group. The inclusion of
a 12B strip is strongly advised.
8. If further speciation is required for Yersinia spp. (i.e. other
than Yersinia enterocolitica and Yersinia pseudotuberculosis), additional testing
is required.
References
1. Identification of Bacteria by Computer: General Aspects and Perspectives.
Lapage, S.P., et al (1973) J. Gen. Microbiology. 77, 273.
2. Comparison
of Microbact 12E, API 20E and Conventional Media Systems for the Identification
of Enterobacteriaceae. Mugg, P.A., (1979) The Australian Journal
of Med. Tech. 10, 37-41.
3. Comparison of Microbact 12E and 24E systems
and the API 20E systems for the Identification of Enterobactiaceae. Mugg, P.A.
and Hill, A., (1981) J.
Hyg. Camb. 87, 287.
4. Biochemical Identification of New Species and Biogroups
of Enterobacteriaceae Isolated from Clinical Specimens. Farmer, J.J., et
al,
(Jan. 1985) J. Clin. Micro., 21 No. 1, 46-76.
5. Evaluation
of the API20E and Microbact 24E Systems for the Evaluation of Pseudomonas
pseudomallei.
A.D. Thomas, (1983) Veterinary Microbiology. 8, 611-615.
6. Biochemical
Characterisics of Enterotoxigenic Aeromonas sp. V. Burke, J. Robinson, H.M.
Atkinson, and M. Gracey, (Jan. 1982) Journal of Clinical Microbiology.
48-52.
7. Comparison of five commercial methods for the Identification of Non-fermentative
and Oxidase Positive Fermentative Gram-Negative Bacilli. Bilkey, Mary K., et
al., (1988) N.Z.J. Med. Lab Technol., 8-12,
8. S.T. Cowen, K.J.
Steel (1977) Manual for the Identification of Medical Bacteria, 2nd
Edition Cambridge University Press.
9. A.Balows, W.J. Hausler, K.L. Herrmann,
J.D. Isengerg, H. Jean Shadomy (eds).
(1991) Manual of Clinical Microbiology, 5th Edition, American Society of Microbiology,
Washington, D.C.