GUIDE (download pdf)

Transcription

SAMPLE PREPARATION
2x
Dilution 1/10
(25 g / 225 ml)
Dilucup
Petrifilm Aqua
Decimal
dilutions
Buffered
peptone
water
Colilert
Pseudalert
Quanti-Tray
Petrifilm
yeast and mould
DryPlates
Vitroids
NeoFilm
TEMPO
Soleris
Eddy Jet 2
SimPlate
NEO-GRID
Buffered
peptone
water
Fraser 1/2
Selective enrichment
broth preparation
1-2 Test
Salmonella
Molecular Detection
System (MDS)
VIP Gold
Listeria
Chromogenic media
plating
Amplified Nucleic Single
Temperature Reaction (ANSR)
Reveal 2.0 Salmonella
AUTOMATED COLONY COUNT
Flash & Go
Scan 1200
ENVIRONMENTAL CONTROL
Rodac plates
MacConkey Agar
Rodac plates
Count-Tact
plates
Count-Tact
plate applicator
FluoroSELECT E.coli
Contact slides
Clean Test
BioFinder
Luminometer
Clean-Trace NG
Hydrated-Sponge
Quick Swab
Sampler
Spin Air
Luminometer
MVP ICON
Listeria Isolation Transwab
Sampler
Sampl’air
Luminometer
AccuPoint Advanced
CHROMOGENIC CULTURE MEDIA
Coliforms / Escherichia coli
Petrifilm rapid
coliform count plate
RAPID’E.coli 2
Petrifilm select
E. coli
chromID Coli
CCA coliform
cromogenic agar
BBL CHROMagar O157
Brilliance
chromogenic
coliform agar
DryPlates EC
Salmonella spp.
ASAP
Chromatic SALMONELLA
Brilliance Salmonella
RAPID’Salmonella
Campylobacter spp.
Brilliance CampyCount
CASA
IRIS Salmonella
Salmonella
chromogenic agar
BBL CHROMagar
Salmonella
CHROMOGENIC CULTURE MEDIA
Staphylococcus aureus
Chromatic
STAPH AUREUS
Baird-Parker RPF
BBL CHROMagar
Staph aureus
Listeria monocytogenes
ALOA
O.A. LISTERIA
COMPASS Listeria
Brilliance Listeria
Listeria
chromogenic agar
RAPID’L.mono
DIAGNOSTIC TESTS AND KITS
Enterobacteria
API
EnteroPluri-Test
Salmonella spp.
Agglutination tests
RapID ONE
Microgen
latex
Oxoid
latex test
DIAGNOSTIC TESTS AND KITS
Listeria monocytogenes
Microgen ID
Microbact Listeria 12 L
Rhamnose test
Campylobacter spp.
TECRA Campylobacter VIA
O·B·I·S·
Different microorganisms
BBL Crystal ID Gram +
Different microorganisms
Enzyme confirmation cards
ID membranes
MYCOTOXIN DETECTION
Reveal Q+ and Accuscan GOLD reader
Selective broths
Chromogenic culture media
Aerobic plate count
DryPlates TC
NeoFilm
SimPlate
2
16
12
Petrifilm rapid coliform count plate
Petrifilm select E. coli
RAPID'E.coli2
chromID Coli
Brilliance chromogenic coliform agar
CCA coliforms chromogenic agar
BBL CHROMagar O157
DryPlates EC
Brilliance Salmonella
RAPID'Salmonella
ASAP
IRIS Salmonella
Chromatic SALMONELLA
BBL CHROMagar Salmonella
Salmonella chromogenic agar
Brilliance Listeria
ALOA
RAPID'L.mono
COMPASS Listeria
O.A. LISTERIA
Listeria chromogenic agar
Baird-Parker RPF
Chromatic STAPH AUREUS
BBL CHROMagar Staph aureus
API 20E
RapID ONE
EnteroPluri-Test
1 Enzyme confirmation cards
1 Differential Coli-E. coli ID Membrane
5 Total Coliform ID Membrane
3
17
15
10
2
5
3
4
13
10
15
17 Microbact Listeria
3 Microgen Listeria ID
5 O·B·I·S· Listeria
4 Rhamnose test (RAPID'L.mono confirmation)
13
15
13 BBL Crystal ID Gram +
10
Brilliance CampyCount
CASA
Petrifilm yeast and mould
17
3
1
Enterobacteria
E. coli /coliforms
Salmonella spp.
L. monocytogenes
ONE Broth Salmonella
RAPID'Salmonella capsules
(for buffered peptone water)
Salmonella enrichment
+ IRIS supplement
17
5
ONE Broth Listeria
17
4
S. aureus
Yeast and mould
Mycotoxins
Water
Others
Vitroids
· E. coli
· S. Enterica
· S. aureus
· L. monocytigenes
Immunological methods
Other rapid count methodologies and/or miniaturization
3
17
13
11
11
11
Soleris
16
TEMPO EC (E. coli )
Colilert
3
14
11 Oxoid Salmonella latex test
Microgen Salmonella latex
Reveal 2.0
1-2 Test
17 Molecular Detection System (MDS)
6 Amplified Nucleic Single Temperature Reaction (ANSR)
16
12
17 VIP Gold Listeria
6
17
5
12
Tecra Campylobacter VIA
Reveal Q+
Petrifilm Aqua
NEO-GRID
Sample prepartion, automation
11 Smart Dilutor W
DiluFlow Pro
Dilucup-DiluShaker
BagMixer SW
Homogenizer Pulsifier
Homogenizer Masticator
Spiral plater Eddy Jet 2
Colony counter Flash & Go
Colony counter Scan 1200
AccusScan Gold
9
18
7
18
6
9
9
9
18
16
Environmental control
Count (colonies)
Count-Tact plates and applicator
MacConkey agar Rodac plates
Contact slide 1
Sampler Sampl'air
Sampler Spin Air
TSA lecithine/polysorbate Rodac plates
HyCheck contact slide
Hydrated-Sponge Neutralizing Buffer
1
16
3
13
13
3
9
10
10
1
Reveal 3D Total Milk Test
Bioluminiscence (ATP)
Luminometer Clean-Trace NG:
· Clean-Trace water - free ATP
· Clean-Trace water - total ATP
· Clean-Trace surface - ATP
Luminometer LIGHTNING MVP
Luminometer AccuPoint Advanced
· AccuPoint ATP Water Sampler
· AccuPoint ATP Acces Sampler
· AccuPoint ATP Surface Sampler
1
16
11
10
Pseudalert
P. aeruginosa
Campylobacter
Reference strains
Diagnostic kits
Colorimetry (proteins)
1 Clean Test
12
16
Others
BioFinder
FluoroSELECT E. coli
14
1
3M España
Laboratorios MICROKIT
16 bioMérieux España
Bioser/Biokar Diagnostics
16 Bioser/Bio-Rad Laboratories
Bioser/Microgen Bioproducts
Bioser/LabRobot Products
ITRAM HIGIENE
13 IUL
BD Dignostic Systems
Sigma-Aldrich Química
MicroPlanet Laboratorios/BioControl Systems
MicroPlanet Laboratorios/Liofilchem
IDEXX Laboratorios
PanReac AppliChem
8 Nirco/Neogen Europe
11 Oxoid
Interscience
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Workshop MRMA: Laboratory sessions 1
Universitat Autònoma de Barcelona
Workshop MRAMA: Laboratory sessions
Schedule
Wednesday, 25th November: 10:15 a.m.-1 p.m.
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Sample preparation and plating automated procedures: homogenizers Pulsifier, Masticator and
BagMixer SW, Smart Dilutor W, DiluFlow Pro, Dilucup-DiluShaker; spiral plater Eddy Jet 2
Rapid viable cell count methodologies: Vitroids (certified reference microorganisms); Petrifilm and
Petrifilm Aqua (plates and reader), NeoFilm, DryPlates; Colilert-18, Pseudalert, Quanti-Tray; NEOGRID (hydrophobic grid membrane); SimPlate; Soleris; colony counters Flash & Go and Scan 1200
Explanation about hands-free "Pop-up" adhesive tape sampling, Fung’s double tube and Fung-Yu
tube
Thursday, 26th November: 10:30 a.m.-1 p.m.
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Environmental control procedures: Count-Tact and RODAC plates, Hycheck and other contact slides,
Quick Swab, Transwab isolation, samplers Spin Air and Sampl’air, MonitorMark
Description and preparation of chromogenic culture media: CASA, ASAP, ALOA, chromID Coli, BairdParker RPF agar, Brilliance CampyCount agar, Brilliance Salmonella agar (Oxoid Salmonella Precis
method), Brilliance Listeria agar (Oxoid Listeria Precis method), Brillance coliform agar,
RAPID’Salmonella, RAPID’E.coli 2, RAPID’L.mono, rhamnose test, IRIS Salmonella agar, COMPASS
Listeria agar, BBL CHROMagar O157, BBL CHROMagar Staph aureus, Chromatic SALMONELLA,
Chromatic STAPH AUREUS, O.A. LISTERIA agar, Salmonella chromogenic agar, Listeria chromogenic
agar, CCA chromogenic agar, ID membranes
Miniaturization: TEMPO EC (enumeration by miniaturized MPN)
Preparation of diagnostic kits: API (kits and reader), BBL Crystal ID (kits and readers), RapID ONE,
O·B·I·S·, Microbact, Microgen ID, EnteroPluri-Test, enzyme confirmation cards
Preparation of molecular detection methods for pathogens (alternatives to PCR): Molecular
Detection System (MDS), Amplified Nucleic Single Temperature Reaction (ANSR)
Friday, 27th November: 9-11 a.m.
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

Reading: rapid viable cell count methodologies, environmental control procedures, chromogenic
culture media, enumeration by miniaturized MPN, diagnostic kits, molecular detection methods for
pathogens
Preparation and reading of other environmental control procedures:
o ATP – bioluminescence: luminometers Clean-Trace NG, AccuPoint and MVP ICON
o colorimetry: Clean-Trace for allergens, Clean Test
o fluorometry: FluoroSELECT
o others: BioFinder
Preparation and reading of immunological detection methods:
o ELISA: Tecra VIA
o confirmation by latex agglutination: Microgen latex, Oxoid latex test
o immunoprecipitation: 1-2 Test for Salmonella
o
lateral immunomigration: VIP Gold, Reveal 2.0, Reveal Q+ for mycotoxins (kits and reader
AccuScan Gold), Reveal 3D for allergens
Overview of the methods employed
1. Wednesday
1.1. Sample preparation and plating automated procedures
- Homogenizer Pulsifier:
The Pulsifier is used for dislodging microorganisms from foods without excessively breaking the food
structure. The Pulsifier has an oval metal ring that can house a plastic bag with sample and diluents. When
the instrument is activated, the ring will vibrate vigorously for a predetermined time (around 30-60s). During
this time, microorganisms on the food surface or in the food will be dislodged into the diluents with the
minimum destruction of the food.
Fung and colleagues in 1988 evaluated the Pulsifier against the Stomacher with 96 different food items
(included beef, pork, fish, shrimp, a variety of vegetables, cereal, etc) and found that the systems gave
essentially the same viable cell count in the food but the “Pulsified” samples were much clearer than the
“Stomached” samples and they had less debris.
- Masticator and BagMixer SW:
- Smart Dilutor W:
The protocol is quite straight forward:
1) A sterile homogenizer bag is placed in the homogenizer bag holder (which serves as a weighing platform).
2) The weight tare is performed.
3) The sample is placed inside the bag.
4) The instrument will then automatically deliver diluent into the bag until a previously preset dilution factor
is reached. Dilution factors can be set through any given rational number fraction: numerator (two digits)/
denominator fraction (three digits).
5) A precisely diluted sample is ready for further processing.
- DiluFlow Pro:
DiluFlow gravimetric dilutors enable the automatic dilution of the sample with perfect reliability.
- Dilucup-DiluShaker:
The Dilucup is delivered in blisters of rows of either 3 or 6 containers, each filled with 9 ml diluting media. It
is easy to separate the number of Dilucups needed. The Dilucups are placed on the tray of the Dilushaker.
The Dilucups are opened by tearing off the film covering the holes in the lids. When the Dilushaker is turned
on, the liquid in all Dilucups rotates. A sample of 1 ml is added to the first cup and is instantly mixed with the
media. After changing the pipette tip, 1 ml of sample is withdrawn from the first cup and added to the
second. With the Dilushaker operating the process is repeated until the required dilution factor is achieved.
- Spiral plater Eddy Jet 2:
1.2. Rapid viable cell count methodologies
- Vitroids:
Vitroids are discs that contain viable microorganisms in a certified quantity. Consisting of pure cultures of
bacteria or fungi in a solid water soluble matrix, they are stable for at least one year and are in a viable state
with a shelf life of 1-3 years.
The preparation can be performed in most solid and liquid medium or rehydration buffer can also be used.
Discs can be rehydrated in as little as 100 µL buffer, or in larger volumes, e.g. 100 mL medium. It is also
possible to add the disc to a cooled molten medium used for pour plate techniques. The rehydration process
takes approximately 10 minutes. On solid media, the disc forms a droplet that can be spread with a sterile
loop. In liquid media, the disc dissolves very quickly.
- Petrifilm and Petrifilm Aqua (plates and reader):
The 3M Petrifilm plate is an all-in-one plating system. They are heavily used in many microbiology-related
industries and fields to culture various micro-organisms and are meant to be a more efficient method for
detection and enumeration compared to conventional plating techniques.
3M Petrifilm™ Aerobic plate count
3M Petrifilm™ Aqua yeasts and moulds
The 3M Petrifilm Aqua AQYM Plate is a sample-ready culture medium system which contains nutrients
supplemented with antibiotics, a cold-water-soluble gelling agent, and an indicator that facilitates yeast and
mold enumeration. 3M Petrifilm Aqua AQYM Plates are used for the enumeration of yeast and mold in
bottled water industry.
3M Petrifilm™ EC/Coliform plate counts
Petrifilm E. coli/Coliform Count (EC) plates contain Violet Red Bile (VRB) nutrients, a cold-water-soluble
gelling agent, an indicator of glucuronidase activity, and an indicator that facilitates colony enumeration.
Most E. coli (about 97%) produce beta-glucuronidase which produces a blue precipitate associated with the
colony. The top film traps gas produced by the lactose fermenting coliforms and E. coli. About 95% of E. coli
produce gas, indicated by blue to red-blue colonies associated with entrapped gas on the Petrifilm EC plate
(within approximately one colony diameter).
- NeoFilm:
- DryPlates:
It is a microbial detection that does not require media preparation. That is why it has the advantages of a
dehydrated media (long expiration term) and prepared medias (sterile, ready for immediate use, timersaver). It cold self-diffuses the sample ml, thus avoiding the need for handles, and eliminating the agar’s
temperature cooling critical point to avoid burning microorganisms and increasing by 10 the plates detection
limit.
- Colilert-18 and Quanti-Tray:
Colilert-18 is a commercially available enzyme-substrate liquid-broth medium that allows the simultaneous
detection of total coliforms and E. coli. It is available in the most-probable number (MPN) or the
presence/absence (PA) format. The MPN method is facilitated by use of a specially designed disposable
incubation tray called the Quanti-Tray.
Two enzyme substrates are included in Colilert—a chromogen that reacts with the enzyme found in total
coliforms (galactosidase), and a fluorogen that reacts with an enzyme found in E. coli (glucuronidase). After
18 or 24 hours incubation at 35ºC, a total- coliform-positive reaction turns the medium yellow; an E. colipositive reaction causes the medium to fluoresce under a long-wave ultraviolet light (366 nm).
- Pseudalert:
The Pseudalert test detects the presence of Pseudomonas aeruginosa in bottled, pool, and spa water
samples. The test is based on a bacterial enzyme detection technology that signals the presence of P.
aeruginosa through the hydrolysis of a substrate present in the Pseudalert reagent. P. aeruginosa cells
rapidly grow and reproduce using the rich supply of amino acids, vitamins, and other nutrients present in the
Pseudalert reagent. Actively growing strains of P. aeruginosa have an enzyme that cleaves the substrate to
produce a blue fluorescence under UV light. Pseudalert detects P. aeruginosa at 1 cfu in either 100 mL or
250 mL samples within 24 hours for non-carbonated water samples and within 26 hours for carbonated
samples.
- NEO-GRID (hydrophobic grid membrane):
NEO-GRID tests are based on the concept of hydrophobic grid membrane filtration. The filter membrane is
embossed with hydrophobic ink to produce a grid containing 1600 individual squares. The ink’s hydrophobic
nature contains the growth of an organism isolated during the filtration process within the square of
capture. Samples are first diluted in a sterile buffer. The NEO-GRID filtration unit is then placed onto a
manifold connected to a vacuum source. Using the vacuum source, a portion of the diluted sample is filtered
through the filter membrane. The membrane is then transferred to an agar plate prepared with a medium
formulated to promote/differentiate the growth of the target organism. Following incubation, the plate’s
squares containing presumptively positive colonies are counted to yield a most probable number (MPN)
result.
- SimPlate:
SimPlate Total Plate Count utilizes proprietary Binary Detection Technology to provide quantitative results
for total aerobic bacteria from food and environmental samples in just 24 hours. Proprietary chromogenic
media and patented plating device with isolation wells combine to produce easily counted results and
eliminate problems associated with food particle interference or liquefying of gels caused by certain
bacterial enzymes.
- Soleris:
The Soleris system is a rapid optical system for the detection of microbial contamination based on an
innovative application of classic microbiology familiar to microbiologists. The optical assay measures
microbial growth by monitoring pH and other biochemical reactions that generate a colour change as
microorganisms in the broth grow and metabolize. The results are displayed by color-coded monitoring with
an alert on samples out of specification.
The technology is based on monitoring changes in the chemical characteristics of microbial liquid growth
medium in which the target microorganisms grow and are detected by optically sensitive reagents. The
reagents change their spectral patterns as the metabolic process takes place. These changes are detected
photometrically by an optical instrument and monitored at predetermined time intervals. The key to the
technology is the monitoring of these changes in a semifluid zone of the patented organism-specific vial. This
zone is separated from the liquid medium, thereby eliminating the masking of the optical pathway by the
sample matrix, or microbial turbidity. Various dyes, which are indicators of metabolic activity such as pH,
redox, and enzymatic and CO2 production, can be utilized in the system.
- Colony counters Flash & Go:
It is an automatic colony counter for pour plates and any type of spiral spreading. Complete instrument with
centering holder for different Petri dishes size. There is a software to count colonies in any media.
- Scan 1200:
2. Thursday
2.1. Environmental control procedures
- Count-Tact and RODAC plates:
- Hycheck and other contact slides:
Hycheck are hygiene contact slides used to assess the microbiological contamination of surfaces or fluids.
They are double sided. Feature a hinged paddle that bends for easy sampling.
- Quick Swab:
It is a ready-to-use environmental swab system to detect microbial contamination. For Dry Sampling:
1) Remove swab from tube and swab targeted area. Place swab back into tube and bring to the lab.
2) Bend red snap valve to transfer all the broth into the tube.
3) Shake or vortex tube vigorously for 10 seconds to release bacteria from swab.
4) Pour contents onto, for example, a Petrifilm Plate.
- Transwab isolation:
If swabs samples are taken from surfaces which have been disinfected, there may still be traces of biocide
which can react with and reduce the count of microorganisms present at the time of sampling. Such
microorganisms may have been part of, and protected by a surface biofilm, and the action of swabbing
loosens them and exposes them to the biocide. This will result in a false low count, and failure to detect a
potential hazard for subsequent food or beverage production. It is essential, therefore, and may be
mandatory, that any residual disinfectant on surfaces is neutralised at the time of sampling by first wetting
the swab in an appropriate neutralising solution.
NRS Medium contains lecithin, polysorbate 80, and sodium thiosulphate, in apeptone phosphate buffer. This
formulation is in accordance with ISO 18593:2004, and will neutralise most disinfectants used in the food
industry, including those based on chlorine, peroxygen compounds, iodine, quaternary ammonium
compounds, amphoterics, biguanides and glutaraldehyde.
- Samplers Spin Air and Sampl’air:
- MonitorMark:
3M MonitorMark Time/Temperature Indicators monitor product temperature exposure through the entire
supply chain. They provide a non-reversible record of temperature exposure that is accurate and easy to
interpret.
2.2. Description and preparation of chromogenic culture media
- CASA:
This medium allows a high selective enumeration of Campylobacter spp. On the selective chromogenic CASA
agar, there is a strong inhibition of growth of the competitive bacteria from the intestinal flora
and Campylobacter colonies appear red and are easily detected.
- ASAP:
It is a chromogenic culture medium for Salmonella detection from food and environmental samples. The
principle of the ASAP medium is based on the detection of C8-esterase activity, which is found in
all Salmonella species. C8-esterase activity of Salmonella is visualized by the pink to purple coloring of their
colonies (specific cleavage of the substrate).
 Pink to purple colonies  C8-esterase detection Salmonella spp.
 Blue to blue-green colonies  Beta-glucosidase detection  Expl: Klebsiella, Enterobacter.
 Violet blue colonies  C8-esterase & beta-glucosidase detection  Expl: Serratia
- ALOA:
ALOA agar is a pre-prepared, selective and differential medium for the isolation of Listeria spp. from food
samples and for the presumptive identification of L. monocytogenes. To minimize the growth of
contaminating organisms, lithium chloride and a balanced antimicrobial and antifungal mixture is employed.
The incorporation of the chromogenic substrate X-glucoside for the detection of beta-glucosidase
demonstrates the presence of Listeria spp., whilst the detection of a specific phospholipase C enzyme
produced by pathogenic Listeria spp. including L. monocytogenes is also achieved. Listeria spp. grow on this
medium producing blue - green colonies, with pathogenic species (L. monocytogenes and L. ivanovii)
producing similar coloured colonies surrounded by a characteristic opaque halo after 24 hours incubation at
37ºC. Non Listeria spp. produce white colonies.
- chromID Coli:
Detection and enumeration of E. coli at 44°C and simultaneous enumeration of E. coli and other coliforms at
37°C, in food products. The chromID Coli medium contains 2 chromogenic substrates, which enable the
simultaneous detection of coliforms and identification of E. coli, without the use of additional reagents.
 β-GAL (+) : presence of coliforms other than E. coli  blue colonies (β-galactosidase).
 β-GUR (+) : presence of E. coli  rose colonies (β-glucuronidase).
- Baird-Parker RPF agar:
Staphylococcus aureus is a Gram-positive coccus capable of producing enterotoxin which can induce food
poisoning. The organisms may be present in small numbers in many foods, and, if allowed to multiply
unchecked, may produce highly heat resistant enterotoxins. The ability of S. aureus to produce lecithinase
and lipase has been recognised for many years, and the detection of these enzymes in egg yolk media has
become a widely used procedure for the identification of this organism. Its ability to produce coagulase
using a similar basal formulation enables confirmatory diagnosis with the incorporation of rabbit plasma into
the base medium.
This medium is a modification of Baird-Parker Medium and is recommended for the selective isolation,
enumeration and confirmation of S. aureus from food and other specimens. The reduction in potassium
tellurite concentration in RPF Agar results in S. aureus strains forming white, grey or black colonies, which
are surrounded by an opaque halo of precipitation, i.e. the coagulase reaction.
- Brilliance CampyCount agar:
Campylobacter is a leading cause of enteric disease in most developed countries. The organism is endemic in
many poultry populations; 98% of food-borne infections are caused by C. jejuni and C. coli. In recent years,
there have been numerous improvements in animal husbandry and carcasses processing that have reduced
the prevalence of Campylobacter in poultry. However, it is unfeasible that the complete elimination of
Campylobacter can be brought about in the near future. However, to reduce human infection, it is generally
accepted that further reduction in the levels of Campylobacter on the fowl is a more feasible goal. In order
to bring this about, a shift in industry standards from a presence/absence testing to enumeration needs to
occur.
Brilliance CampyCount Agar is a transparent medium which makes identification of C. jejuni and C. coli
significantly easier than on traditional charcoal or blood containing agars. It contains an indicator that, when
metabolised by the target organisms, changes colour. As it builds up in the cells it turns colonies dark red,
making all C. jejuni and C. coli colonies readily identifiable. The components of Brilliance CampyCount Agar
have been carefully designed to maximise growth of C. jejuni and C. coli while inhibiting non-target
organisms. This defined formulation means the medium can be used to accurately enumerate the loading of
C. jejuni and C. coli on poultry carcasses and related samples.
- Brilliance Salmonella agar (Oxoid Salmonella Precis method):
An Inhibigen compound is comprised of two components, combined together by a bond that can only be
cleaved by a specific enzyme. When bound together, the inhibitor compound is not toxic and therefore can
exist in a medium without harming microorganisms. Once inside the cell, the bond will be cleaved if the
target enzyme is present. When the bond is cleaved, the inhibitor molecule is released and disrupts cell wall
synthesis, causing death of the organism. As cells die and lyse, free inhibitor is released but cannot be taken
up by other cells, resulting in targeted inhibition. The Inhibigen in Brilliance Salmonella Agar targets E. coli.
Novobiocin and cefsulodin, presented as a freeze-dried supplement, are added to the medium to inhibit the
growth of other competing flora such as Proteus spp. and Pseudomonas spp.
Differentiation of Salmonella from the other organisms that grow on Brilliance Salmonella Agar is achieved
through the inclusion of two chromogens that also target specific enzymes: caprylate esterase and ßglucosidase. Caprylate esterase is an enzyme present in all samonellae as well as some species
of Klebsiella, Enterobacter and Proteus. Organisms possessing caprylate esterase cleave the chromogen to
release an insoluble purple chromophore. As the cells grow, the chromophore builds up and produces a
purple-coloured colony. Some Enterobacteriaceae, including Klebsiella and Enterobacter but not Salmonella,
possess ß-glucosidase. If these organisms grow, they will form blue or dark blue colonies, even if they are
esterase positive, which make them easy to differentiate from purple Salmonella colonies.
- Brilliance Listeria agar (Oxoid Listeria Precis method):
Brilliance Listeria Agar uses the chromogen X-glucoside for presumptive identification of Listeria spp. This
chromogen is cleaved by ß-glucosidase which is common to all Listeria species. Other organisms that possess
this enzyme, such as enterococci, are inhibited by the selective agents within the medium; lithium chloride,
polymyxin B and nalidixic acid, whilst amphotericin inhibits the growth of any yeasts and moulds present in
the sample. Listeria monocytogenes and pathogenic Listeria ivanovii are then further differentiated by their
ability to produce the phospholipase enzyme, lecithinase. This enzyme hydrolyses the lecithin in the
medium, producing an opaque white halo around the colony. The medium is designed to
identify Listeria spp. based on their utilisation of a chromogenic substrate. However, in this modification, the
pathogenic Listeria spp. are then further differentiated by the detection of lecithinase (phosphotidylcholine
phospholipase C (PCPLC) activity, rather than phosphotidylinositol phospholipase C (PIPLC) activity. Both
enzymes, PCPLC and PIPLC, are associated with virulence in Listeria spp., and, therefore, the presence of
either enzyme is a useful indicator of pathogenicity.
- Brilliance E.coli/colifomr agar:
Brilliance E.coli/coliform agar is a differential agar used for the presumptive identification of Escherichia
coli and coliforms from food and environmental samples. The agar base uses two enzyme substrates to
differentiate between E. coli and other coliforms. One chromogenic substrate is cleaved by the enzyme
glucuronidase, which is specific for E. coli and produced by approximately 97% of strains. The second
chromogenic substrate is cleaved by galactosidase, an enzyme produced by the majority of coliforms. This
results in purple E. coli colonies, as they are able to cleave both chromogenic substrates, and pink coliform
colonies, as they are only able to cleave the galactosidase chromogen.
- RAPID’Salmonella:
The principle of RAPID’Salmonella chromogenic medium relies on the demonstration of two enzymatic
activities. Salmonella spp. takes the form of readily identified typical magenta colonies (detection of C8
esterase). Counter selection based on β-D-Glucosidase is used to reveal other bacteria with a different color.
As expected in the regulations, RAPID’Salmonella permits detection of motile and non-motile Salmonella, as
well as lactose-positive Salmonella, Salmonella Typhi and Salmonella Paratyphi.
- RAPID’E.coli 2:
RAPID’E.coli 2 is a selective chromogenic medium used for direct enumeration without confirmation, of
coliforms including Escherichia coli. The principle of the medium relies on simultaneous detection of two
enzymatic activities: β-D-Glucuronidase (GLUC) and β-D-Galactosidase (GAL). Coliforms (GAL+/GLUC-) form
blue to green colonies, E. coli (GAL+/GLUC+) forms violet to pink colonies.
- RAPID’L.mono:
The RAPID’L.mono chromogenic medium specifically detects the phospholipase of Listeria monocytogenes
and its inability to metabolize xylose. After 24 hours of incubation, L. monocytogenes forms characteristic
blue colonies without a yellow halo.
- Rhamnose test:
- IRIS Salmonella agar:
IRIS Salmonella Agar shows a high specificity for the detection of Salmonellae including atypical species and
serovars, which is a source of confusion on other medium. Indeed, the detection of Salmonella Typhi and
Paratyphi, lactose-positive Salmonellae (Salmonella Senftenberg and subspecies S. arizonae and S.
diarizonae), saccharose-positive strains are ensured. The media allows the detection of non-motile serovars
(S. Pullorum and S. Gallinarum) or monophasic strains. IRIS Salmonella Agar allows also the detection of
strains which show a light or absence of esterasic activity on other medium (Salmonella Bongori, Salmonella
Dublin and Atento, certain strains of S. houtenae and S. diarizonae subspecies). The selective agents permit
the inhibition of Gram-positive and some Gram-negative bacteria. IRIS Salmonella Agar may be used in the
standard methods for the detection of Salmonellae as second isolation medium.
- COMPASS Listeria agar:
COMPASS Listeria Agar allows the detection of blue colonies surrounded by an opaque halo, typical of
Listeria monocytogenes.
The peptones and growth factors (yeast extract, sodium pyruvate and magnesium sulfate) favor the
excellent growth of Listeria monocytogenes. Yeast extract is also a source of vitamin B complex. Sodium
chloride maintains the osmotic equilibrium of the media. Listeria hydrolyzes the 5-bromo-4-chloro-3-indolylβ-D-glucopyranoside (or X-β-glucoside). The resulting product is subjected to an oxidative dimerization that
forms a blue precipitate in the center of the colonies. Phosphatidyl-inositol is used as a substrate for the
detection of phospholipase C of Listeria monocytogenes. When it is degraded, an opaque precipitate is
formed around the colonies. Secondary microflora is inhibited by the association of lithium chloride and a
judicious mixture of selective agents that include several antibiotics and an antifungal agent.
- BBL CHROMagar O157:
CHROMagar O157 is intended for the isolation, differentiation and presumptive identification of E. coli
O157:H7. Due to the chromogenic substrates in the medium, colonies of E. coli O157:H7 produce a mauve
color, thus allowing presumptive identification from the primary isolation plate and differentiation from
other organisms. Gram-negative organisms, other than E. coli O157:H7, will either be inhibited or produce
colorless, blue, green, blue-green (aqua) or natural color colonies.
- BBL CHROMagar Staph aureus:
S. aureus is a well documented pathogen. It is responsible for infections ranging from superficial to systemic.
Due to the prevalence of this organism and its clinical implications, detection is of utmost importance.
Staphylococcal food poisoning caused by S. aureus is one of the most common types of foodborne illness
worldwide. Its detection and enumeration help provide information about the potential health hazard of
food, as well as being an indicator of poor hygiene. It is also recommended that this organism can be used as
an indicator of water quality.
BBL CHROMagar Staph aureus is intended for the isolation, enumeration and identification of S. aureus
based on the formation of mauve-colored colonies. The addition of chromogenic substrates to the medium
facilitates the differentiation of S. aureus from other organisms. The addition of selective agents inhibits the
growth of gram-negative organisms, yeast and some gram-positive cocci. The chromogen mix consists of
artificial substrates (chromogens), which release an insoluble colored compound when hydrolyzed by
specific enzymes. This facilitates the detection and differentiation of S. aureus from other organisms. S.
aureus utilizes one of the chromogenic substrates, producing mauve-colored colonies. The growth of mauvecolored colonies at 24 h is considered positive for S. aureus on BBL CHROMagar Staph aureus. Bacteria other
than S. aureus may utilize other chromogenic substrates resulting in blue, blue-green, or if no chromogenic
substrates are utilized, natural colored colonies.
- Chromatic SALMONELLA:
Proteose Peptone and meat extract provide amino acids and proteins. Yeast extract is a source of amino
acids and vitamins of group B. Sodium chloride maintains the osmotic balance of the medium. The special
chromogenic mix allows differentiation of Salmonella spp., including S. typhi, from other coliform and noncoliform bacteria, on the basis of the colour and the morphology of the colonies. Beside the chromogenic
mix inhibits Gram-positive microorganisms. Tween 20 increases microbial growth.
Salmonella typhimurium and other Salmonella species will appear as light mauve to mauve – colored
colonies. Citrobacter and other coliforms will appear as light blue- green to blue- green colored colonies.
Some organisms that do not hydrolyze any of the chromgenic compounds may appear as colorless colonies.
Final identification must be performed by biochemical and/or serological tests.
- Chromatic STAPH AUREUS:
It is a selective chromogenic medium for isolating Staphylococcus aureus. Peptone is a source of amino acids
and proteins. The selectivity is due to the concentration of sodium chloride and the composition of the
chromogenic mix which allows differentiation of S. aureus from other staphylococci.
Staphylococcus aureus grows with pink-mauve colonies; Staphylococcus xylosus and Staphylococcus sciuri
grow with blue turquoise colonies; Gram-negative bacteria are completely inhibited. Final identification
must be done by biochemical and serological tests.
- O.A. LISTERIA agar:
The selectivity of the medium is due to lithium chloride and to the addition of antimicrobial selective mixture
containing ceftazidime, polymyxin B, nalidixic acid and cycloheximide. The differential activity is due to the
presence in the medium of the chromogenic compound X-glucoside as a substrate for the detection of βglucosidase enzyme, common to all Listeria species. The specific differential activity is obtained by means a
substrate (L-α-fosphatidylinositol) for a phospholipase C enzyme that is present in Listeria monocytogenes.
Thanks to the combination of two substrates, it is possible to differentiate the colonies of Listeria spp, which
grow with a green-blue colour, from the colonies of Listeria monocytogenes which grow with green-blue
colonies surrounded by an opaque halo.
- Salmonella chromogenic agar:
Salmonella Chromogenic Agar Base combines two chromogens for the detection of Salmonella sp., 5-Bromo6-Chloro-3-Indolyl caprylate (Magenta-caprylate) and 5-Bromo-4-Chloro-3-Indolyl b-D galactopyranoside (Xgal). X-gal is a substrate for the enzyme b-D-galactosidase. Hydrolysis of the chromogen, Mag-caprylate, by
lactose negative Salmonella species results in magenta colonies.
The medium contains bile salts to inhibit the growth of Gram-positive organisms and the addition of the
Salmonella Selective Supplement is recommended to increase the selectivity of the medium. This uses
novobiocin to inhibit Proteus growth and cefsulodin to inhibit growth of Pseudomonads.
- Listeria chromogenic agar:
Meat peptone and Tryptone provide nitrogen, vitamins, minerals and amino acids essential for growth. Yeast
extract is the source of vitamins, particularly of the B-group. Sodium chloride supplies essential electrolytes
for transport and osmotic balance. Sodium pyruvate is a source of energy for bacterial metabolism and aids
in resuscitation of stressed organisms. Glucose is the fermentable carbohydrate providing carbon and
energy. Magnesium glycerophosphate is a buffering compound. Magnesium sulphate is a magnesium ion
required in a large variation of enzymatic reactions, including DNA replication. The differential activity of the
medium is due to two factors. Lithium chloride in the base medium and supplementary antimicrobial
compounds Ceftazidime, Polymyxin, Nalidixic acid and Cycloheximide provide the medium’s selectivity.
Bacteriological agar is the solidifying agent.
The presence of the chromogenic component X-glucoside, a substrate for the detection of the enzyme ßglucosidase, is common to all Listeria species giving the colonies their blue colour. Other organisms that
possess this enzyme, for example Enterococci, are inhibited by the selective agents within the medium and
by the selective supplement. The differential activity is also obtained by lipase C substrate, upon which the
specific enzyme for L. monocytogenes acts. The lipase is responsible for the opaque white halo which
surrounds L. monocytogenes. The combination of both substrates allows us to differentiate the colonies of
Listeria monocytogenes from the rest of Listeria spp. since, although all are blue in colour, L. monocytogenes
present an opaque white halo surrounding them.
It has been observed that some strains of Listeria ivanovii, mostly pathogenic to animals although some have
caused infections in humans, also possess lipase activity.
- CCA chromogenic agar:
CCA Chromogenic Agar is a culture medium for the enumeration of Escherichia coli and coliform bacteria
after membrane filtration stage. The CCA is based on enzymatic reactions that give colour to the colonies of
target organisms for simultaneous detection of coliforms and E. coli. This medium is suitable for samples
with low microbial load as drinking water, swimming pools, disinfected waters and water treatment plants at
the end of the treatment.
Count ß-galactosidase positive colonies and ß-glucuronidase negative colonies (all colonies coloured from
salmon-rose to red) as coliform bacteria different from E. coli. Count ß-galactosidase positive colonies and ßglucuronidase positive colonies (all colonies coloured from deep blue to violet) as E. coli. Total coliform
count is obtained by the addition of the salmon-rose to red colonies plus the deep blue to violet colonies.
- ID membranes:
These membranes are for economical and rapid identification and confirmation of microorganisms in water,
food, environmental and clinical samples. They find their application in various sectors in food and dairy
industry, water industry, etc.
The membranes contain chromogenic substrates such as ONPG, X-Gal, or X-Glu and other substrates and
indicators which serve as the basis for the differentiation by color. The target organisms are characterized by
enzyme systems that metabolize the substrates and initiate the color change. The colors can then be visually
detected on the membranes and show the enzymatic activity of the microorganisms which is a helpful tool
for the identification of genus and species.
2.3. Miniaturization
- TEMPO EC (enumeration by miniaturized MPN)
The TEMPO instrument is the food industry’s first automated quality indicator testing system for the
enumeration of quality indicator organisms in food and environmental samples.
TEMPO is based on the Most Probable Number (MPN) method. The principle of the MPN method is to allow
any microorganism present in samples to grow in suitable conditions in tubes, using a minimum of three
dilutions and three tubes per dilution.
BioMérieux has automated and miniaturized this method, which was previously time-consuming and subject
to errors due to the numerous steps involved.
2.4. Preparation of diagnostic kits
- API (kits and reader):
The API (Appereils et Procedes d’Identification) microbial identification test system consists of an array of
around 20 e.g. API 20E. Each of the mini-test tubes contains dehydrated media and reagents that are
designed to detect the presence or, absence of selected biochemical pathways production, in the microbe of
concern.
To perform an API test, pure microbial growth e.g. a colony from an agar plate, is mixed with sterile saline
solution to form a microbial inoculum of the correct density; this is manually dispensed into each of the
mini-test tubes using a sterile pipette. Some of the mini-test tubes are filled completely, while others are
filled partially and overlaid with sterile mineral oil to provide anaerobic conditions. After inoculation, the
strip is placed in a plastic incubation box along with some water, to prevent moisture loss from the mini-test
tubes during incubation. After incubation at an appropriate temperature e.g. 37°C, for an appropriate length
of time e.g.18 to 24 hours, growth and reagent utilisation is assessed by either by colorimetric, fluorescent
or turbidity means - sometimes this requires the addition of extra reagents. For example, one drop of
Kovac’s reagent has to be added to develop the indole (IND) reaction; one drop of TDA reagent (10% ferric
chloride) to develop the tryptophan deaminase (TDA) reaction; one drop of VP1 (40% potassium hydroxide)
followed by one drop of VP2 (6% alpha naphthol) for the Voges Proskaueur reaction; and one drop of
oxidase reagent for the cytochrome oxidase (OX) reaction.
The reactions of each test tube are recorded with the aid of the manufacturer’s interpretation.
- BBL Crystal ID (kits and readers):
The BBL Crystal ID kits feature an easy-to-use identification method using fluorogenic and chromogenic
reagents. Various BBL Crystal Kits are offered to identify several gram-negative, gram-positive, and anaerobic
organisms. BBL Crystal ID Kits provide one-step convenience, easy inoculation, and a comprehensive list of
organisms that can be identified. Following an incubation period, the sample can be manually read on the
Crystal panel viewer to obtain a profile number.
- RapID ONE:
The RapID ONE System is a qualitative micromethod employing conventional and chromogenic susbtrates
for the identification of medically important Enterobacteriaceae and other selected oxidase-negative, gramnegative bacilli isolated from food, water, human clinical specimens, etc.
A clear plastic tray contains reagent impregnated wells, allowing simultaneous inoculation of each cavity
with a predetermined volume of inoculum. A suspension of test organism in RapidID inoculation fluid is used
as the inoculums which rehydrates and initiates test reactions. After incubation, each cavity is examined for
reactivity by noting the development of a color. In some cases, reagents must be added to the cavities to
provide a color change. The resulting pattern of positive and negative scores is used as the basis for
identification of the test isolate by comparison of the test results to reactivity patterns stored in a database
or through the use of a computer-generated code compendium (ERIC).
- O·B·I·S·:
The O.B.I.S. mono test offers a rapid screening method for differentiation of Listeria monocytogenes from
other Listeria species. This reduces the need for full biochemical identification of all suspect colonies. Listeria
species, with the exception of Listeria monocytogenes, possess the enzyme D-alanyl aminopeptidase. Oxoid
has developed a new system for aminopeptidase testing which uses a non-carcinogenic substrate. This is in
response to health concerns associated with amino acid conjugates of ß-naphthylamine4,5 as these are
potent carcinogens. D-alanyl-7-amido-4-methylcoumarin (DALA) is provided as a suspension. An acidic
solution of dimethylaminocinnamaldehyde is used as a colour developer. If the substrate is hydrolysed by
DALAase, free 7-amino-4-methylcoumarin (7AMC) combines with the developer to produce a purple Schiff’s
base.
Pick colonies which have typical Listeria morphology from selective Listeria isolation media such as Oxford
Agar, PALCAM Agar and chromogenic Listeria Media, and streak onto a purity plate.
- Microbact:
The Microbact range offers a selection of self-contained, biochemical-based tests for the identification of key
pathogenic bacteria, including Gram-negative bacteria, Listeria species and Staphylococcal species.
- Microgen ID:
It is a standardized bacterial identification system. Presented in convenient microwell formats, these
systems provide flexible identification platforms which in turn provide savings in cost, time and key
laboratory space (incubation and storage).
- EnteroPluri-Test:
EnteroPluri-Test makes possible the identification of the Enterobacteriaceae and other gram negative,
oxidase negative bacteria isolated from non-clinical samples. The identification is based on biochemical tests
performed on culture media containing specific substrates. The combination of positive and negative
reactions allows building up a code number that permits to identify bacteria by using the Codebook.
- Enzyme confirmation cards:
These tests utilize a specific substrate which, when hydrolyzed by a specific enzyme of the target organism
(during peptide hydrolysis), produces a blue/white fluorescence, or purple/blue color upon the addition of
Reagent B (color developer) when applicable.
2.5. Preparation of molecular detection methods for pathogens (alternatives to PCR)
- Molecular Detection System (MDS):
The 3M Molecular Detection System was conceived as a molecular microbiology approach that could detect
pathogens from food samples and samples taken from processing environments. The system is based on a
combination of two technologies: Isothermal DNA amplification and bioluminescence detection. These two
“pillar” technologies work together to provide a molecular detection method that is pure and simple.
The principle behind is that it uses multiple primers to recognize distinct regions of the genome and Bst DNA
polymerase to provide continuous and rapid amplification of genetic material. Pyrophosphate ions (PPi), a
by-product of the targeted DNA amplification reaction, and APS, are enzymatically converted into ATP by
ATP-Sulfurylase. ATP reacts with luciferase to produce light which is detected indicating the presence of
target organism DNA. Both amplification and detection occur simultaneously and continuously during the
exponential phase providing real time results and a short run time.
- Amplified Nucleic Single Temperature Reaction (ANSR):
The food industry has emphasized a need for a quicker, easier and precise pathogen test to lessen the
chances of contaminated food products reaching their customers. Unlike other molecular technologies,
ANSR (Amplified Nucleic Single-Temperature Reaction) utilizes patent-pending, unique amplification reaction
technology for in vitro DNA amplification at a constant temperature. ANSR provides genetic level detection
of low level specified targets in as little as 10 minutes following enrichment. ANSR’s enrichment and assay
result in minimal matrix effects compared to conventional methods, in both food matrices and
environmental samples.
3. Friday
3.1. Preparation and reading of other environmental control procedures
3.1.1. ATP-bioluminescence
- Luminometers Clean-Trace NG:
3M Clean-Trace NG Luminometer NG3 is a simple, quick and reliable hand held diagnostic tool to verify
cleaning effectiveness and capture, store and manage data for later analysis.
- AccuPoint:
The AccuPoint Advanced ATP Hygiene Monitoring System is a handheld device that accurately detects ATP
from surfaces and rinse water samples. The three colour-coded samplers with liquid-stable chemistry are
unrivalled in their accurate recovery of ATP from surfaces and rinse waters. Unlike traditional swabs utilised
by other manufacturers, our samplers cover a larger surface area to extract ATP more consistently.
- MVP ICON:
The MVP ICON is the first system to provide true HACCP management capabilities. Featuring advanced
photon counting sensor (PCS) technology, the MVP ICON provides superior accuracy, sensitivity, and
reproducibility for ATP, pH, temperature, conductivity, and concentration. The innovative design is sleek,
lightweight and features an easy to use touch-screen interface.
3.1.2. Colorimetry
- Clean-Trace for allergens:
Residues remaining on surfaces indicate poor cleaning and provide nutrients for spoilage or pathogenic
bacteria to thrive, which could lead to product contamination. With the unique swab-click-read format and
simple color change technology, this 3M test is very easy to use and implement in a busy production
environment. The results are semi-quantitative with four possible colors. The faster the test turns purple the
higher the level of contamination on a surface. The test detects protein and other reducing agents,
considered as a superior hygiene indicator to glucose as more difficult to remove from a surface.
- Clean Test:
The 3M Clean-Trace is based on the measurement of levels of ATP present on an environmental surface. A
3M Clean-Trace ATP Surface Test is used to swab a selected test point. The test is then activated and the
swab is brought into contact with the test enzyme solution (luciferin-luciferase). The enzyme reacts with any
ATP residue present on the swab bud. A product of this reaction is the generation of light by the enzyme
solution. The Clean-Trace ATP Surface Test is then placed in the 3M Clean-Trace NGi Luminometer. This
measures the light generated by the enzyme solution and produces a result expressed in Relative Light Units
(RLUs). The greater the level of ATP present on the swab, the greater the amount of light generated by the
test and consequently, the higher the RLU level produced. The test can be performed in less than 30
seconds, providing a real-time result that indicates the cleanliness of the surface tested. This provides an
opportunity to take any corrective action required such as re-cleaning and re-testing the surface.
3.1.3. Fluorometry
- FluoroSELECT:
The FluoroSELECT Assay system is a presumptive screen intended for the rapid detection of E. coli, Gramnegative bacteria, methicillin resistant Staphylococcus aureus (MRSA) and total coliform from a surface swab
sample using the FluoroSELECT handheld fluorometer and the fluorescent assay.
FluoroSELECT utilizes specific fluorogenic substrates which are cleaved from characteristic enzymes of E. coli,
Gram-negative bacteria, MRSA or total coliform. During the typical peptide hydrolysis, the specific enzymes
hydrolyze the fluorogenic substrates and produce a fluorescence which is read by a portable, low cost
fluorometer. The excitation wavelength is at 360 nm, respectively 480 nm while the emission wavelength is
at 460 nm (blue) or 530 nm (green), the intensity of which is then measured to decide if the sample is
positive or negative. It is a rapid test since the assay takes maximum 30 minutes, although it may require
some incubation time. Because the enzymes are specific, the assay is highly specific and robust. In addition,
since it is a typical fluorescence assay, it is also highly sensitive and small amounts of the cleaved fluorogen
will already have been detected.
3.1.4. Others
- BioFinder
It reacts to detect the group of microorganisms attached to surfaces, called Biofilms. It immediately reveals
contaminated areas by simple visual inspection. It can be applied to the most commonly used surfaces in the
food industry, such as stainless steel, polypropylene and epoxy-coated surfaces. Biofinder has advantages
over other methods, with time and cost reduction being the most significant ones. It simplifies monitoring
surface hygiene of industrial processes. Its formula and packaging type make it possible to treat large areas.
It doesn’t stain or leave residues on surfaces due to its high water solubility which aids in rinsing. Thanks to
its simple application and response type, technical staff is not required for handling. It is not considered
hazardous to the environment, according to current legislation.
3.2. Preparation and reading of immunological detection methods
3.2.1. ATP-bioluminescence
- Tecra VIA:
3M Tecra VIA Tests detect pathogens and toxins in raw materials, finished product or environmental
surfaces in production facilities.
3.2.2. Confirmation by latex agglutination
- Microgen latex:
Microgen latex is a latex slide agglutination test for the confirmatory identification of presumptive
pathogenic colonies from selective agar plates.
- Oxoid latex test:
A loop full of material is taken from the top of a positive indicator tube, for example, Salmonella Rapid Test
and it is mixed with a drop of the latex test reagent. If agglutination of the latex test reagent occurs, then
Salmonella is present in the material. Similarly, presumptive Salmonella colonies can be taken from an agar
plate, mixed with the latex test reagent and agglutination will occur if Salmonella is present.
3.2.3. Immunoprecipitation
- 1-2 Test for Salmonella:
The 1-2 Test is highly sensitive and specific. It uses a unique combination of a built-in selective enrichment,
the immunodiffusion principle, and a proprietary preparation of antibodies to detect Salmonella.
3.3. Lateral immunomigration
3.3.1. Immunoprecipitation
- VIP Gold:
VIP Gold is a single-step visual immunoassay for the detection of pathogens in food and environmental
samples. Each device contains a proprietary reagent system, which forms a visually apparent antigenantibody-chromogen complex if the pathogen is present.
- Reveal 2.0:
Reveal 2.0 for Salmonella is a simple yet sophisticated lateral flow technology that is easy to perform with
minimal sample touch time. This robust lateral flow technology lends itself to multiple food matrices and is
scalable to any operation—from low volumes to a theoretically unlimited throughput. Reveal 2.0 for
Salmonella continues the tradition of convenient unitized-irradiated media which eliminates need for
autoclaving. The simple assay procedure produces clear results in 15 minutes following enrichment.
- Reveal Q+ for mycotoxins:
Reveal Q+ for mycotoxins, a range of simple tests to detect precise amounts of mycotoxins in grain and feed
samples. Due to the known severe threat to human and animal health, more than 100 countries have
established regulatory limits for mycotoxins in commodities intended as human food or animal feed. The
Reveal Q+ product line adds to Neogen’s unrivalled range of simple and accurate lateral flow, microwell and
immunoaffinity column mycotoxin testing options.
For example: Aflatoxin is considered by many to be the most potent, naturally-occurring carcinogen known.
It has been linked to a variety of health problems in both humans and animals. Aflatoxin is a by-product of
mould growth in a wide range of commodities. Two moulds that are major producers of aflatoxin are
Aspergillus and A. parasiticus.
- Reveal 3D for allergens:
Neogen Reveal 3-D food allergen kits are easy-to-use and interpret strip tests that screen samples for the
detection of trace levels of specific food allergens in 10 minutes or less. The unique Reveal 3-D tests allow for
rapid screening for the presence of low levels of allergen in CIP rinses and environments swabs virtually
anywhere. The Reveal 3-D allergen tests utilize a 3-line readout: a control line confirms the method has been
performed successfully and two further lines differentiate low & high levels of detection.

GUIDE (download pdf)

Transcription

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