Food and Water Testing

Chromogenic Media
Reference Guide

CONTENTS

Contents

PART 1 GENERAL INSTRUCTIONS

1Introduction
Sample Preparation/Enrichment
Plate Inoculation

1
2
4

Streak-Plate Inoculation		

4

Spread-Plate Inoculation		5

Pour-Plate Inoculation		

5

Membrane Filtration		

6

Confirmation

7

Colony Confirmation with iQ-Check Protocol

7

Colony Confirmation with Latex Confirmation Test

8

Confirmation of iQ-Check Positive Result		
with RAPID' Chromogenic Media

9PART 2 RAPID' MEDIA DESCRIPTIONSAND USAGE TIPS FOR FOOD TESTING

10

AL (Agar Listeria according to Ottaviani and Agosti)
RAPID'B.cereus Agar
RAPID'Campylobacter Agar
RAPID'E.coli O157:H7 Agar
RAPID'E.coli 2 Agar
RAPID'Enterobacteriaceae Agar
RAPID'Listeria spp. Agar
RAPID'L.mono Agar
RAPID'Sakazakii Agar
RAPID'Salmonella Agar
RAPID'Staph Agar

10PART 3 RAPID' MEDIA DESCRIPTIONSAND USAGE TIPS FOR WATER TESTING

21

RAPID'E.coli 2 Agar for Water Testing
RAPID'P.aeruginosa Agar for Water Testing

21

PART 4 APPENDIX

23

This booklet is provided by Bio-Rad only for the use of Bio-Rad products. It is not a contractual document.

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22

General Instructions

Introduction
RAPID' chromogenic media are used to detect and enumerate microorganisms in food, water, andother samples using simple protocols developed to optimize laboratory workflow and offering results
in a shorter time than classical methods.

Step 1: Sample Preparation/Enrichment*
Recovery of the target bacteria with a balance
between nutrition and selectivity.
* Enrichment not required for enumeration protocol.

Step 2: Plate Inoculation
Detection of the target bacteria by a specific andvisible typical colony.

Step 3: Confirmation**
Verification that the typical colony corresponds tothe target bacteria.
** Confirmation not required for all protocols.

1 | Chromogenic Media Reference Guide

GENERAL INSTRUCTIONS

Sample Preparation/Enrichment
RAPID' chromogenic media are used to detect and enumerate microorganisms in foodproducts (which may be raw material ingredients, in-process food samples, or final products),
in environmental samples (which may be sponges, swabs, carcass rinses, process water, andothers), and in water for human consumption.
Often, sample preparation is dependent on the matrices being tested; some products havespecific requirements. These requirements can be found by referencing standard methods (forexample, ISO, USDA MLG, FDA BAM). Alternative rapid methods sometimes have a different
enrichment scheme that has been optimized to fit the method.
For a quantitative method (one that counts the actual number of bacteria present in the sample),there is no enrichment step. The sample is homogenized with a diluent (1:10) and testing is
performed starting there. Decimal dilutions can be made when high levels of contamination are
expected.

10 –1

10 –1

10 –2

10 –3

10 –4

10 –2

10 –3

10 –4

10 –5

Chromogenic Media Reference Guide | 2

General Instructions

For qualitative methods, which test for presence or absence of target bacteria, an enrichment stepis needed for growing the bacteria in the sample to a level high enough to be detected by a test
method. The enrichment step must balance nutrition, to grow target organisms, and selectivity, tolimit the growth of competing flora.

Log
Phase

Stationary
Phase

Number of bacteria

Lag
Phase

Time

3 | Chromogenic Media Reference Guide

Death
Phase

GENERAL INSTRUCTIONS

Plate Inoculation
Streak-Plate Inoculation
Isolation of small volume (10 µl)
Using a calibrated sterile loop, place 10 µl of sample on the outside edge of the agar surface.
Using a back-and-forth motion, streak for isolation by spreading the deposit in relatively close
streaks over the entire dish from the edge of the previous spread.
Sterile loop

Isolation of large volume (100 µl)
Using a sterile pipet, collect 0.1 ml of sample and place drops on the outside edge of half of the agar
surface. Using a sterile pasteur pipet or inoculating loop, spread sample over half of the agar surface
in a back-and-forth motion. On the other half of the agar surface, streak for isolation by spreading
the deposit in relatively close streaks over the entire dish from the edge of the previous spread. Thismethod may be used when inoculating RAPID'L.mono, RAPID'Listeria spp., and AL Agars.

Endingpoint

0.1 mldepositStartng
point

Starting
point

Endingpoint

Chromogenic Media Reference Guide | 4

General Instructions

Spread-Plate Inoculation
Add 0.1 ml of sample or its decimal dilutions in the center of one dry petri dish. Spread evenly over
the agar surface.

1. Pipet inoculum onto thesurface of agar plate.

2. S pread evenly over
the agar surface.

3. Incubate.

4. Colonies grow only on
the surface of medium.

Pour-Plate Inoculation
Add 1 ml of sample to an empty petri dish. Pour approximately 18 ml of medium tempered to
44–47°C. Mix by swirling gently. Let solidify.

1. Pipet inoculum
onto sterile plate.

5 | Chromogenic Media Reference Guide

2. A
 dd sterile medium.

3. Mix by swirlingand incubate.

4. Colonies grow inand on medium.

GENERAL INSTRUCTIONSMembrane Filtration
Bacteria in a water sample need to be concentrated by running the sample through a filtration
apparatus connected to a vacuum pump or flask. Add 100 ml–1 L of sample to the filtration funnel
containing a 0.45 µm porosity membrane. Once water is filtered, carefully remove the membrane
and transfer it to the surface of the agar plate.

1. Use a 0.45 µm membranefilter on a support.

3. Place the filter membranein the plate containing
appropriate medium.

2. Concentrate sample
by filtering water.

4. Incubate.

5. A
 ssess typical colonies.

Chromogenic Media Reference Guide | 6

General Instructions

Confirmation
Colony Confirmation with iQ-Check Protocol
1.	Pick an isolated colony from the agar surface with a toothpick, sterile loop, or other adapted
consumable.
2.	Resuspend the colony in 100 μl tryptone salt or distilled sterile water in a microcentrifuge tube.
Homogenize using a vortexer.
3.	Use 5 μl of the suspension with 45 μl of iQ-Check PCR mix to run the PCR reaction.

CFX96 Deep Well
Real-Time System™

C1000 Touch
Thermal Cycler™

C1000 Touch™ Thermal Cycler

1
New Protocol

7 | Chromogenic Media Reference Guide

New Protocol

Tools

Log in2

3

Protocol Automator

Saved Protocols

GENERAL INSTRUCTIONSColony Confirmation with Latex Confirmation Test

1. Select an isolated colony (or subculture as appropriate).
It is important to use a pure culture.

2. P lace one free falling drop of antisera onto aslide for agglutination and add a pure colony.

3. Mix reagent and colony together.

4. Rock the slide in a circular motion for
30 sec and observe for agglutination.

No agglutination = negative result

Agglutination = positive result

Chromogenic Media Reference Guide | 8

General Instructions

Confirmation of iQ-Check Positive Result with RAPID' Chromogenic Media
1.	Collect the appropriate volume of the selective enrichment (10 or 100 µl). In the case of
nonselective enrichment (for example, iQ-Check Salmonella II), perform a subculture inselective broth.
2.	Place a drop on the outside edge of the plate and streak to obtain isolated colonies.
3.	Incubate under the appropriate conditions, then read the plate.

CFX96 Deep Well
Real-Time System™

C1000 Touch
Thermal Cycler™

C1000 Touch™ Thermal Cycler

1
New Protocol

9 | Chromogenic Media Reference Guide

New Protocol

Tools

Log in2

3

Protocol Automator

Saved Protocols

FOOD TESTING

RAPID' Media Descriptions and Usage Tips
for Food Testing
AL (Agar Listeria according to Ottaviani and Agosti)
Detection and enumeration of Listeria monocytogenes and other species of Listeria in foodproducts for human consumption and in environmental samples
AL Agar is based on the simultaneous detection of activities of two enzymes: b-D-glucosidase andphosphatidylinositol-specific phospholipase C (PIPLC). The b-D-glucosidase activity, common to all
Listeria, is detected using a chromogenic substrate (X-glucoside). Hydrolysis of this substrate by the
Listeria genus leads to the production of blue to blue-green colored colonies. PIPLC is an enzyme
detected only in pathogenic Listeria species, L. monocytogenes and L. ivanovii. AL medium contains
phosphatidylinositol, which, when broken down, produces an opaque halo around colonies of bacteria ofthese two species. This halo generally appears after 24 hr of incubation in L. monocytogenes and after
48 hr of incubation in L. ivanovii. Selectivity of the medium is achieved by the combined action of lithium
chloride, antibiotics, and an antifungal.
How to Read a Plate

Listeria monocytogenes

Listeria ivanovii

Listeria innocua

Total inhibition: gram-negative bacteria, Enterococcus faecium, Staphylococcus aureus

Keys to Success■■■

AL Agar can be used as a second medium in many standard methods such as ISO, FDA BAM, andHealth Canada
For easy reading and the production of a distinct halo, allow the dishes to dry shortly before use until nodroplets are visible on the surface of the medium
In the presence of a low concentration of L. monocytogenes among Listeria species, the specific enzymesof L. monocytogenes can be inhibited, leading to the production of typical colonies. Using the appropriate
amount of inoculum in order to obtain well-isolated colonies allows the expression of these enzymes andthe production of typical colonies even in samples with high bacterial competition

Chromogenic Media Reference Guide | 10

RAPID' Media Descriptions and Usage Tips
for Food Testing
RAPID'B.cereus Agar
Detection and enumeration of the Bacillus cereus group (vegetative cells and spores) in 24 hr(without confirmation) in food products for human consumption
RAPID'B.cereus Agar is based on a chromogenic reaction and phospholipase activity. Typical B. cereus
colonies develop a characteristic red color generally surrounded with an opaque halo. The medium’s
selective mixture prevents the growth of the interfering flora and enables the analysis of a broad rangeof foods. The sensitivity of the medium has been specially optimized to allow growth of all pathogenic
B. cereus strains, even those that are difficult to culture, such as B. cytotoxicus. The interpretation of
RAPID'B.cereus Agar is further facilitated by the high level of contrast between the color of the colonies
and the agar.

How to Read a Plate

Bacillus cereus

Bacillus cytotoxicus

Bacillus mycoides

Total inhibition: gram-negative bacteria, other Bacillus spp., Enterococcus faecalis

Keys to Success
■
■

■

■

Inoculate agar using the pour-plate method, ensuring that the molten agar is 44–47°C before use
For easy reading, dry the dishes shortly before use until no droplets are visible on the surface ofthe medium
A small percentage of B. cereus strains do not express phospholipase activity (red colonies without
opaque halo), especially when the pour-plate protocol is used. These red colonies should be considered
typical without any form or size criteria
The time lapse between the end of preparation of the stock solution (or 10 –1 dilution, in the case of asolid product) and when the dilutions come into contact with the culture medium must not exceed
45 min11 | Chromogenic Media Reference Guide

FOOD TESTING

RAPID'Campylobacter Agar
Detection and enumeration of the main species of thermophilic Campylobacter in 24 hr (without
confirmation) in food products for human consumption and in environmental samples
The use of a selected nutritive mixture associated with a reducing agent allows the growth ofthermotolerant Campylobacter spp. in an optimal time. Other bacterial species, as well as yeasts andmolds, are inhibited by the selective agents. Campylobacter produce brick-red colonies.

How to Read a Plate

Campylobacter jejuni

Campylobacter coli

Campylobacter lari

Total inhibition: most gram-negative bacteria, most gram-positive bacteria, extended-spectrum beta-lactamase(ESBL)–producing bacteria (such as Escherichia coli and Acinetobacter spp.)

Keys to Success
■
■

■

■

Maintenance of appropriate microaerobic conditions is critical for the growth of Campylobacter
For easy reading, dry the dishes shortly before use until no droplets are visible on the surface of themedium. Avoid prolonged drying so as not to modify the efficiency of the medium. Do not dry plates in alaminar flow hood
Confirming fewer than 5 colonies involves a risk of making an overestimation because of the presence oftypical colonies that could be bacteria other than Campylobacter spp.
If colonies are not easily countable after 24 hr of incubation, reincubate the plate for a total of 48 hr

Chromogenic Media Reference Guide | 12

RAPID' Media Descriptions and Usage Tips
for Food Testing
RAPID'E.coli O157:H7 Agar
Detection of Escherichia coli O157:H7 in food products for human consumption and in environmental
samples
RAPID'E.coli O157:H7 Agar is a selective medium combining chromogenic substrates and biochemical
indicators. This combination provides direct presumptive identification of E. coli O157:H7, including
atypical strains, among the interfering flora on the basis of the specific metabolic and enzymatic profiles
observed. The selectivity of the medium is increased by adding the selective agents novobiocin (10 mg/L)
and potassium tellurite (0.8 mg/L). Typical E. coli O157:H7 (sorbitol– and b-glucuronidase–) presentcharacteristic bright, bulging colonies measuring 1–2 mm, dark blue to black in color, with a slight black
precipitate around the edges of the colonies. Atypical b-glucuronidase+ strains form colonies of the same
type. Strains of atypical sorbitol+ E. coli O157:H7 are also detected. These colonies will have a blue toturquoise color with a weak black precipitate around the edges of the colonies.
How to Read a Plate

Escherichia coli
O157:H7

Escherichia coli
non-O157:H7

Escherichia coli
O157:H7 (sorbitol+)

Total inhibition: gram-positive bacteria, other Escherichia coli

Keys to Success
■

■
■

■

For easy reading, dry the dishes shortly before use until no droplets are visible on the surface of themediumThe agar will turn completely red in the presence of pure strains of E. coli O157:H7
On agar with a mixture of strains, typical E. coli O157:H7 produce dark blue to black colonies with aslight black precipitate around the edges of the colony, sometimes combined with a red halo
Performing the immunomagnetic separation step requires sufficient training and regular practice of thetechnique to obtain valid, reliable results

13 | Chromogenic Media Reference Guide

FOOD TESTING

RAPID'E.coli 2 Agar
Detection and enumeration of colonies of Escherichia coli and other coliform bacteria in 24 hr(without confirmation) in food products for human consumption and in animal feed
RAPID'E. coli 2 Agar relies on the simultaneous detection of the activity of two enzymes: b-D-glucuronidase(GLUC) and b-D-galactosidase (GAL). These enzymes react with the chromogenic substrates present in themedium to produce specific colors. A substrate specific to GLUC leads to pink coloration of colonies positive
for this enzyme. A substrate specific to GAL leads to blue coloration of colonies positive for this enzyme.
The detection of GLUC makes the culture medium highly specific, as E. coli is one of the only species ofcoliforms to possess this enzyme. E. coli (GAL+/GLUC+) form violet to pink colonies. Other coliforms(GAL+/GLUC–) form blue colonies. Other bacteria are inhibited by the selective mixture.

How to Read a Plate

Escherichia coli

Citrobacter spp.
Klebsiella spp.

Salmonella spp.

Escherichia coli
O157:H7

Total inhibition: gram-positive bacteria

Keys to Success
■
■

■
■

Inoculate agar using the pour-plate method, ensuring that the molten agar is 44–47°C before use
For medium prepared in advance, avoid overheating (in general, 20 min is enough to obtain ahomogenous liquid agar)
The agar must not undergo more than two regeneration cycles
As development of colonies at the bottom of the petri dish may interfere with reading, the period
between the deposition of the inoculum in the dish and the dispensing of the culture medium should
be limited

Chromogenic Media Reference Guide | 14

RAPID' Media Descriptions and Usage Tips
for Food Testing
RAPID'Enterobacteriaceae Agar
Detection and enumeration of Enterobacteriaceae in 24 hr (without confirmation) in food products
for human consumption, in animal feed, and in environmental samples
RAPID'Enterobacteriaceae Agar relies on the ability of Enterobacteriaceae to ferment glucose. Due tothe simultaneous presence of crystal violet and bile salts, the medium inhibits gram-positive bacteria
and some gram-negative bacteria. The combination of color indicators allows a high level of contrast ofEnterobacteriaceae colonies, which appear red on a clear gray medium.

How to Read a Plate

Escherichia coli

Salmonella spp.

Acinetobacter spp.

Pseudomonas spp.

Total inhibition: gram-positive bacteria

Keys to Success■■■

Inoculate agar using the pour-plate method, ensuring that the molten agar is 44–47°C before use. Do
not autoclave the medium
As development of colonies at the bottom of the petri dish may interfere with reading, the period
between the deposition of the inoculum in the dish and the dispensing of the culture medium should
be limited
It is preferable to use a double-layered medium with matrices containing abundant mesophilic flora.
The aim of the second layer is to limit overgrowth of these bacteria of the surface, which can interferewith reading

15 | Chromogenic Media Reference Guide

FOOD TESTING

RAPID'Listeria spp. Agar
Detection and enumeration of all Listeria spp. in food products for human consumption and inenvironmental samples
RAPID'Listeria spp. Agar is based on the detection of b-D-glucosidase activity by a chromogenic
substrate. All Listeria colonies are blue to blue-green. The selectivity of the medium is optimized by the
combined action of lithium chloride and an antibiotic mixture.

How to Read a Plate

Listeria spp.

Total inhibition: gram-negative bacteria such as Escherichia coli and Enterococcus faecalis

Keys to Success■■

RAPID'Listeria spp. Agar is ideal for isolating Listeria without differentiation of species
For easy reading, dry the dishes shortly before use until no droplets are visible on the surface ofthe medium

Chromogenic Media Reference Guide | 16

RAPID' Media Descriptions and Usage Tips
for Food Testing
RAPID'L.mono Agar
Detection and enumeration of Listeria monocytogenes and other species of Listeria in foodproducts for human consumption and in environmental samples
RAPID'L.mono Agar relies on the specific detection of the PIPLC activity of L. monocytogenes andon the inability of this species to metabolize xylose. After 24 hr of incubation, L. monocytogenes formcharacteristic blue (pale blue, gray-blue, or dark blue) colonies without a yellow halo. Colonies formedby other species of Listeria are white, with or without a yellow halo. L. ivanovii form blue-green colonies
with a yellow halo (xylose-positive characteristic). This halo can appear after 24–48 hr of incubation.
The selective solution in the medium permits inhibition of most interfering flora (gram-positive andgram-negative bacteria, yeasts, and molds).

How to Read a Plate

Listeria monocytogenes

Listeria ivanovii

Listeria welshimeri

Listeria innocua

Total inhibition: gram-negative bacteria, Staphylococcus aureus

Keys to Success
■

■

■

■

 APID'L.mono Agar can be used as a second medium in many standard methods such as ISO,R
FDA BAM, and Health Canada
When inoculating a high volume of sample (0.1 ml), the dishes can be left on the work surface for
15–30 min to permit complete absorption
Differentiation between L. ivanovii and L. monocytogenes is based on the metabolism of xylose, which
lowers pH and changes the color of the agar, forming a yellow halo. Any irregular change of the pH froma high concentration of lactic acid bacteria, an acidic sample, or the use of insufficiently distilled watermight interfere with reading the results
In the presence of a low concentration of L. monocytogenes among other Listeria species, the specificenzymes of L. monocytogenes can be inhibited, leading to the production of atypical colonies. Using theappropriate amount of inoculum to obtain well-isolated colonies allows the expression of these enzymes
and the production of typical colonies even in samples with high bacterial competition

17 | Chromogenic Media Reference Guide

FOOD TESTING

RAPID'Sakazakii Agar
Detection of Cronobacter spp. (formerly Enterobacter sakazakii) in milk powders, infant formula andraw materials, and in environmental samples
RAPID'Sakazakii Agar is based on the detection of the a-glucosidase enzymatic activity characteristicof Cronobacter spp. Under this action, the chromogenic substrate 5-bromo-4-chloro-3-indolyl
a-D-glucopyranoside is hydrolyzed, producing Cronobacter spp. colonies with a blue to blue-green color.
Sodium deoxycholate and crystal violet inhibit the growth of competing microflora.

How to Read a Plate

Cronobacter sakazakii

Other Cronobacter spp.

Salmonella spp.

Escherichia coli

Total inhibition: probiotic bacteria, gram-positive bacteria

Keys to Success■■■

Enrichment is a key step to ensure the full recovery of all Cronobacter spp. The quality of the buffered
peptone water (BPW) broth has a major impact on the recovery of rare and stressed cells. RAPID'Sakazakii
validation has been performed with Bio-Rad BPW Plus
For large sample sizes, the short protocol using the PIF Supplement will improve the handling and thesensitivity of the RAPID'Sakazakii method and allow for simultaneous enrichment of Cronobacter spp.
and Salmonella spp.
The association of a selective mix and a high incubation temperature of 44°C ensures the inhibition of
the growth of background flora and probiotics found in certain matrices

Chromogenic Media Reference Guide | 18

RAPID' Media Descriptions and Usage Tips
for Food Testing
RAPID'Salmonella Agar
Detection of Salmonella spp. in food products for human consumption, in animal feed, and inenvironmental samples
RAPID'Salmonella Agar allows the presumptive identification of motile and nonmotile Salmonella spp. bydetecting C8-esterase activity. Simultaneous screening of b-glucosidase activity permits the differentiationof Salmonella colonies from those of other Enterobacteriaceae. After incubation, Salmonella appear as
readily identifiable — typically magenta — colonies, whereas non-Salmonella bacteria grow as blue orcolorless colonies. RAPID'Salmonella Agar permits detection of motile and nonmotile Salmonella, as wellas lactose-positive S. Typhi and S. Paratyphi.

How to Read a Plate

Salmonella Typhimurium

Salmonella Dublin

KES bacteria,
Citrobacter spp.

Escherichia coli

Total inhibition: gram-positive bacteria, Pseudomonas spp.

Keys to Success
■

■

■

■

Enrichment is a key step to ensure the full recovery of all Salmonella. The quality of the BPW broth has
a major impact on the recovery of rare and stressed Salmonella cells. RAPID'Salmonella validation has
been performed with Bio-Rad BPW Plus
Some low–C8-esterase Salmonella, such as S. Dublin, can produce pale magenta colored colonies.
All pink to magenta colonies must be considered presumptive Salmonella
In the presence of a high level of background flora and bacterial competition, specific enzymes ofSalmonella can be inhibited and don’t produce the typical phenotype. Isolation of the appropriate
amount of inoculum to obtain well-isolated colonies allows the expression of the typical phenotype of
Salmonella, even in samples with high bacterial competition
For large sample sizes, the short protocol using the PIF Supplement will improve the handling andsensitivity of the RAPID'Salmonella method and allow for simultaneous enrichment of Salmonella spp.
and Cronobacter spp.

19 | Chromogenic Media Reference Guide

FOOD TESTING

RAPID'Staph Agar
Detection and enumeration of coagulase-positive staphylococci (Staphylococcus aureus and otherspecies) in food products for human consumption, in animal feed, and in environmental samples
RAPID'Staph Agar is based on a Baird-Parker formula optimized for the detection and enumeration of
coagulase-positive staphylococci such as S. aureus in 24 hr. The principle of the medium relies on thecapacity of S. aureus to reduce tellurite (black colonies) and induce the proteolysis of egg yolk (clear haloaround colonies).

How to Read a Plate

Staphylococcus coagulase+

Total inhibition: most coagulase-negative and gram-negative bacteria

Keys to Success■

Inoculate agar using the pour-plate method, ensuring that the molten agar is 44–47°C before use■

For easy reading, dry the dishes shortly before use until no droplets are visible on the surface of the medium■■

The time lapse between the end of preparation of the stock solution (or 10 –1 dilution, in the case of a solid
product) and when the dilutions come into contact with the culture medium must not exceed 45 minSome coagulase-positive Staphylococcus strains can require an additional 24 hr incubation for the halo to
be clearly visible

Chromogenic Media Reference Guide | 20

RAPID' Media Descriptions and Usage Tips
for Water Testing
RAPID'E.coli 2 Agar for Water Testing
Direct enumeration of Escherichia coli and other coliform bacteria in 21 ± 3 hr (without confirmation)
in water for human consumption
RAPID'E.coli 2 Agar for Water Testing allows simultaneous detection of the activity of two enzymes,
b-D-glucuronidase (GLUC) and b-D-galactosidase (GAL), by two chromogenic substrates. Cleavage ofthe GAL-specific substrate forms a precipitate, giving a blue color to the colonies positive for this enzyme(coliforms). Cleavage of the GLUC-specific substrate forms a precipitate giving a pink color to the colonies
positive for this enzyme (E. coli). Coliforms (GAL+/GLUC–) produce blue colonies. E. coli (GAL+/GLUC+)
produce violet to pink colonies due to the superposition of both colors. The selective mixture in the
supplement inhibits the main interfering flora in water.

How to Read a Plate

Escherichia coli

Other coliforms

Total inhibition: major interfering flora in water such as Citrobacter, Enterobacter, Hafnia, Klebsiella, Serratia,
Acinetobacter, Aeromonas, Bacillus, Proteus, Pseudomonas, Salmonella, Shigella, Staphylococcus, and Vibrio strains

Keys to Success
■

■
■

■
■

■

Place the membrane, cross-hatched surface up, on the surface of the medium, taking care that themembrane-agar contact is complete
Always use a sterile filter membrane (47 mm, 0.45 μm)
Avoid trapping air bubbles underneath the membrane during its placement on the agar. Poor
membrane-agar contact may lead to an erroneous result. If necessary, gently and carefully flatten themembrane with forceps
Retain only dishes that contain a maximum of 110 colonies
To ensure the physiological integrity of reference cells, preparation of a fresh calibrated suspension froma strain cultured on a nutritive medium is recommended. The use of other commercial reference material
is also possible
The incubation time and temperature conditions are suitable for simultaneous use with
RAPID'P.aeruginosa Agar

21 | Chromogenic Media Reference Guide

WATER TESTING

RAPID'P.aeruginosa Agar for Water Testing
Direct enumeration (without confirmation) of Pseudomonas aeruginosa in 22 hr in water forhuman consumption
RAPID'P.aeruginosa Agar is based on the detection of an enzymatic activity typical of P. aeruginosathat cleaves a specific chromogenic substrate, leading to the formation of a blue to blue-green or green
precipitate. The selective mixture makes it possible to inhibit the majority of interfering flora, in particularother Pseudomonas strains that are not aeruginosa. Other microorganisms may, however, show growth.
Their colonies appear transparent or pigmented yellow-green and are easily distinguishable from those of
P. aeruginosa.

How to Read a Plate

Pseudomonas aeruginosa
Total inhibition: Pseudomonas other than P. aeruginosa, and major interfering flora in water such as Acinetobacter spp.,
Aeromonas spp., Escherichia coli, and Xanthomonas spp.

Keys to Success
■

■
■

■
■

Place the membrane, cross-hatched surface up, on the surface of the medium, taking care that themembrane-agar contact is complete
Always use a sterile filter membrane (47 mm, 0.45 μm)
Avoid trapping air bubbles underneath the membrane during its placement on the agar. Poor
membrane-agar contact may lead to an erroneous result. If necessary, gently and carefully flatten themembrane with forceps
Retain only dishes that contain fewer than 50 characteristic colonies and fewer than 100 colonies total
The incubation time and temperature conditions are suitable for simultaneous use with RAPID'E.coli 2
Agar for Water Testing

Chromogenic Media Reference Guide | 22

Appendix

Quality and Certification

ISO/IEC 17025 Accreditation

Our quality policy, which is the result of our dedicated efforts
to food and water environmental and surface testing, is basedon a constant commitment to improvement.

ISO/IEC 17025 accreditation allows solution manufacturers
and user laboratories to demonstrate that they operatecompetently and use reliable and valid products for reliable
and valid results. The Bio-Rad culture media quality control
Within the scope of the CE labeling process for all of its medical laboratory in Steenvoorde, France is ISO/IEC 17025 accredited
diagnostic activities, a number of Bio-Rad sites received ISO(N° 1-6642 by COFRAC Essais). Scope of accreditation is13485 certification in 2002. The Bio-Rad ISO 9001 version 2000 available at cofrac.fr.
certification is also maintained for all of its activities.
United States Department of Agriculture (USDA) and Foodand Drug Administration (FDA) inspections have confirmed
Bio-Rad quality systems’ and products’ compliance with
U.S. regulatory standards.

Production

Distribution
Stock is maintained in a temperature-controlled environment
with barcode readings of code, batch, expiration date,
product status, commercial validity, and country authorization
verified at each step in product storage and distribution.

From the delivery of raw materials right up to marketing of thefinished products, Quality Assurance applies to every productmanufactured by Bio-Rad. Each batch of finished products
undergoes strict quality control testing and is marketed only
if it complies with acceptance criteria.

Normally, products are transported at room temperature.
Bio-Rad takes shipping-related stress conditions into accountwhen developing reagents. This allows reagents to be carried
via standard shipping services. For those rare instances whena product’s performance cannot be guaranteed under these
conditions, Bio-Rad offers specialized methods of transport.

All documentation relating to the production and quality control
of a given batch is archived.

Traceability
All Bio-Rad products can be traced electronically, making
it possible to identify the customer(s) linked with a specificproduct and/or batch or serial number.
As part of the company’s “reagent vigilance,” this traceability
makes it possible to inform clients when there’s a problem
with a particular batch or lot number, to indicate any actions
to be taken based on the results, and, where applicable, torecall a given product.

23 | Chromogenic Media Reference GuideAPPENDIX

Bibliography

Safety Data Sheets

ISO 6887-1:2017. Microbiology of the food chain —Preparation of test samples, initial suspension and decimal
dilutions for microbiological examination — Part 1: Generalrules for the preparation of the initial suspension anddecimal dilutions.

These are established by our Department of Regulatory
Affairs for every product containing hazardous substances
and are recorded in the product reference information. These
safety data sheets are available upon request.

ISO 7218:2007. Microbiology of food and animal feeding stuffs— General requirements and guidance for microbiologicalexaminations.
ISO 11133:2014. Microbiology of food, animal feed and water— Preparation, production, storage and performance testingof culture media.

Certificates of Health and Origin
These documents, available during audit, are delivered to us
by our suppliers for peptones of animal origin when they are
elements in the composition of a product.

Brochures

ISO 19458:2006. Water quality — Sampling for
microbiological analysis.
United States Department of Agriculture. Microbiology
Laboratory Guidebook.
United States Food and Drug Administration. Bacteriological
Analytical Manual.

Technical Data Sheets
For more information about our products, please refer tothe technical data sheets.
Depending on the products, our technical sheets include:■ Applications of the product■ Corresponding standard references■ Product description■ Presentation or type(s) of packaging offered■ Stock status■ Typical formula■ N ecessary product(s) or material(s) that are not supplied■ Detailed protocols■ Special precautions for use■ Quality controls indicating test strains and expected results
All of our technical data sheets are available on our website.

Quality Control Certificates
These certificates have been established for every productand indicate all the control tests carried out on the finishedproduct, the expected specifications, and the results obtained.

RAPID'Chromogenic
Media Brochure
Bulletin 16288

iQ-Check Real-Time PCR
Solution Brochure
Bulletin 16439

Visit bio-rad.com/foodscience
for more information.
VideosVisit the Bio-Rad Food Science video
library, which includes product tutorials,
technical information, and more.

bio-rad.com/FoodScienceVideos
BIO-RAD is a trademark of Bio-Rad Laboratories, Inc. IQ-CHECK
is a trademark of Bio-Rad Europe GmbH in certain jurisdictions. All
trademarks used herein are the property of their respective owner.

These documents can be consulted online and can be
downloaded in PDF format by using a product code andbatch number.

Chromogenic Media Reference Guide | 24

Appendix

Ordering Information
Catalog #Description

Catalog #Description

AL (Agar Listeria according to Ottaviani and Agosti)
3563695	Ready to use, 90 mm x 20 dishes
3563965	Ready to use, 90 mm x 120 dishes
3564043	Dehydrated base, 500 g
3555200	Base medium, 237.5 ml x 6 bottles
3564041	Supplement 1, 10 vials
3564042	Supplement 2, 10 vials

RAPID'L.mono Agar
3563694	Ready to use, 90 mm x 20 dishes
3563964	Ready to use, 90 mm x 120 dishes
3555294	Kit: 190 ml + supplement 23564293	Dehydrated base, 500 g
3564294	Supplement 1, 10 vials
3564746	Supplement 2, 10 vials

RAPID'B.cereus Agar
12007304	Ready to use, 90 mm x 20 dishes
12007305	Dehydrated base, 500 g
12007306	Supplement 1, 10 vials
12007307	Supplement 2, 10 vials

RAPID'Sakazakii Agar
3563971	Ready to use, 90 mm x 20 dishes
3564976	Dehydrated base, 500 g

RAPID'Campylobacter Agar
12012036	Ready to use, 90 mm x 20 dishes
3564295	Dehydrated base, 500 g
3564296	Supplement, 10 vials
RAPID'E.coli O157:H7 Agar
3564748	Dehydrated base, 100 g
RAPID'E.coli 2 Agar
3555299	Ready to use, 100 ml x 6 bottles
3555297	Ready to use, 200 ml x 6 bottles
3564024	Dehydrated base, 500 g
RAPID'Enterobacteriaceae Agar
3554012	Ready to use, 200 ml x 6 bottles
3564004	Dehydrated base, 500 g
RAPID'Listeria spp. Agar
3564744	Dehydrated base, 500 g
3564745	Supplement 1, 10 vials
3564746	Supplement 2, 10 vials

RAPID'Salmonella Agar
3563961	Ready to use, 90 mm x 20 dishes
3563963	Ready to use, 90 mm x 120 dishes
3564705	Dehydrated base, 500 g
3564709	Enrichment supplement capsules,
10x concentrated, 100 capsules
3564710	Enrichment supplement capsules,
100 capsules
3564712	Enrichment supplement,
100 analyses
RAPID'Staph Agar
3563960	Ready to use, 90 mm x 20 dishes
3564704	Dehydrated base, 500 g
RAPID'E.coli 2 for Water Testing3563982
Ready to use, 55 mm x 20 dishes
3555299
Ready to use, 100 ml x 6 bottles
3555297
Ready to use, 200 ml x 6 bottles
3564024
Dehydrated, 500 g
12008041
Supplement, 6 vials (for 200 ml bottles)
17005373 	Ready-to-use kit (for 200 ml), includes
6 bottles of agar and 6 vials of supplement
RAPID'P.aeruginosa Agar for Water Testing3563984
Ready to use, 55 mm x 20 dishes
3564900
Dehydrated, 500 g

25 | Chromogenic Media Reference GuideAPPENDIX

Notes

Chromogenic Media Reference Guide | 26

Notes27 | Chromogenic Media Reference Guide

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