Colorex Listeria (ISO)
Recent developments in culture media have given rise to the use of chromogenic substrates as a means of differentiating bacteria. This is one such medium and is a selective medium for the isolation and presumptive identification of Listeria monocytogenes from clinical and food samples. The medium is made selective by the inclusion of Lithium chloride, Ceftazidime, Polymixin B, Nalidixic acid (to suppress other bacteria) and Amphotericin B (to suppress yeasts and fungi). With the combination of both the chromogenic substrate and phospholipase C enzyme reactions, it is possible to differentiate L.monocytogenes from other Listeria spp. Users should be aware that some strains of L.ivanovii are capable of producing an opaque halo, highlighting the need to confirm presumptively identified colonies.
Mineral Modified Glutamate Medium with 1.5% Agar
A modification of Mineral Modified Glutamate Medium where 15g/Litre of Agar has been added to create a plating medium suitable for the isolation of E.coli from food samples. Using this medium during the resuscitation stage allows for the recovery of E.coli from frozen, dried, heat-processed or low pH foods.
Braziers CCEY Agar
Brazier’s CCEY Agar with 1% Lysed Horse Blood – Blood, Cycloserine, Cefoxitin, 4% Egg Yolk Emulsion
Based on Fastidious Anaerobe Agar, Cholic Acid and p-Hydroxyphenylacetic Acid are added to enhance the isolation and differentiation of Clostridium difficile from clinical specimens. Cholic Acid promotes spore germination and p- Hydroxyphenylacetic Acid enhances production of p-cresol, a distinctive metabolite of Clostridium difficile. The medium is made selective by the inclusion of Cefoxitin and D-Cycloserine and Egg Yolk emulsion is added to differentiate Clostridium difficile from the Lecithinase producing clostridia. Lysed Blood is also added which optimises the colony fluorescence when cultures are examined under UV light.
Mueller Hinton w 2% NaCl(25ml)
Approved by the National Committee for Clinical Laboratory Standards (NCCLS) in USA this medium is approved for use in antimicrobial sensitivity testing by the disc diffusion method and is recommended particularly for use with the Bauer-Kirby Technique It is low in Thymine and Thymidine and is therefore suitable for use in testing Sulphonamides & Trimethoprim and controlled to ensure correct zone sizes with Tetracyline and Aminoglycoside antibiotics. It can be considered as an alternative to Iso-Sensitest Agar. This particular formulation has an additional 2% Sodium Chloride added to the medium making it suitable for the detection of resistance to Methicillin in staphylococci and it is included in the recommendations of British Society for Antimicrobial Chemotherapy (BSAC) for this purpose. It is not however recommended for testing of organisms requiring a CO2 enriched environment due to the pH effect on the medium. If incubation in a CO2 enriched environment is essential control organisms should be included to confirm that results have not been altered.
Colorex™ mSuperCARBA™ is a selective chromogenic medium that has been developed for the detection and isolation of carbapenemase producing Enterobacteriaceae (CPE). Nosocomial infections due to CPE are particularly difficult due to the limited treatment options. Therefore, this medium is designed to simplify the detection of CPE carriers and to allow for improved monitoring of high risk patient groups. The distinctive colonial colouration of the various species can reduce the need for additional follow up testing allowing many positive results to be issued within 24 hours of receipt of the sample. All presumptive positive colonies should be confirmed for carbapenemase production.
Typical colour reactions are as follows:
Escherichia coli – Red/Pink colonies;
Klebsiella spp., Enterobacter spp., & Citrobacter spp. – Metallic blue colonies;
Other Gram –ve CPE – Colourless colonies;
Carbapenem sensitive bacterial species, Gram +ve bacterial species & yeasts – Inhibited.
Chromogenic medium for detection of Clostridium difficile.
Clostridium difficile (C.difficile) is the leading cause of nosocomial infectious diarrheoa in adults. These infections occur mostly in patients who have both medical care and antibiotic treatment and have become more frequent and more difficult to treat in the last years due to the emergence of highly toxigenic C.difficile strains.
Although PCR has become the leading C.difficile detection technique, culture is essential for strain typing and antimicrobial susceptibility testing. CHROMagarTM C.difficile is a new fluorogenic culture medium, extremely sensitive and selective, especially designed to simplify and speed up (24h) the culture of C.difficile.
Colorex StrepB Agar
About a quarter of pregnant women in the UK are estimated to carry Streptococcus agalactiae. As a result of this, babies become colonized with Streptococcus agalactiae (GBS) during labour and birth; the vast majority are unaffected by this colonization, however, a small percentage become infected with conditions such as eye infections, pneumonia, septicaemia or meningitis. Colorex™ StrepB Agar is a chromogenic media that presumptively identifies Streptococcus agalactiae (mauve/red colonies) after 18-24 hours incubation in aerobic conditions. Enterococci are differentiated by the formation of blue colonies; other organisms are inhibited or colourless.
NB: Some strains of Group A, C & G streptococci may also produce mauve colonies. Therefore, final identification may require additional testing.
Colorex MRSA (15ml)
Colorex™ MRSA is a chromogenic medium for the selective isolation of Methicillin-Resistant Staphylococcus aureus (MRSA). The medium can be used for the routine screening of clinical specimens for MRSA from a variety of sampling sites such as the nose, throat and groin. The medium incorporates a nutritious peptone base medium and a number of selective agents to inhibit most Gram-negative and Gram-positive bacteria as well as yeasts and moulds. The chromogenic detection of specific enzyme activity leads to the formation of pink/mauve colonies indicating MRSA (including low level resistant and hetero-resistant strains) following incubation at 37°C for 18-24 hours. Other organisms, if present are indicated by blue or colourless colonies. Any presumptive isolates must be confirmed using serological and/or biochemical techniques available to the laboratory. The use of this chromogenic medium does not diminish the requirement for conventional antimicrobial susceptibility tests for the confirmation of methicillin resistance.
1. S.aureus strains that possess a low MIC to the selective agent present in the medium but are mec A negative may form colonies on the medium.
2. Some MRSA strains may form typical colonies surrounded by a matte halo. The formation of the halo serves no diagnostic function.
3. Certain methicillin-resistant coagulase-negative staphylococci (CNS) may produce characteristic colonies. In some cases differentiation may be achieved by examination of the colour of these colonies, as they may be considerably darker in colour (bluish purple to a very dark pink/magenta).
4. Certain bacterial species other than staphylococci may produce colonies with a characteristic colour.
Vancomycin-resistant Enterococcus (VRE) infections are especially aggressive and have been associated with mortality rates approaching 60% to 70%. They are now the second-leading cause of nosocomial infections in the U.S., and their prevalence is increasing worldwide. Resistance to vancomycin has the potential to be transferred from bacteria to bacteria. Cross-resistance is mediated by plasmids and transposons, which may transfer the genes associated with resistance to other much more aggressive pathogens, such as staphylococci and streptococci. Three principal types of vancomycin resistance are found in Enterococcus spp.; VanA, VanB and VanC genotypes. VanA and VanB types account for most significant infections in clinical settings, involving E.faecium and E.faecalis. VanC resistance is a low-level intrinsic resistance found in other Enterococcus spp. The Colorex™ VRE media is another chromogenic media in the Colorex™ range, enabling presumptive identification of vancomycin resistant Enterococci by the formation of mauve/pink coloured colonies (for VanA and VanB genotypes) and blue coloured colonies (for VanC genotypes) after 18-24 hours incubation.
Colorex Staph aureus
This is a chromogenic medium for the isolation and presumptive identification of Staphylococcus aureus. Mauve colonies indicate Staph aureus following incubation (18 – 24 hours) at 37°C, other organisms, if not inhibited, are indicated by blue or colourless colonies. Studies have suggested that this media has a specificity and sensitivity of 99.4% and 95.5% respectively (Gaillot et al 2000).
Colorex O157 CT
Colorex 0157 with Cafixime & Tellurite
This medium replaces the conventional Sorbitol MacConkey Agar that is reputed for high levels of false positives and the difficulty of colonial interpretation and differentiation. Colorex O157 is a chromogenic medium with a very high specificity (98% according to K.A. Bettelheim, 1998 J.Appl.Microbiol.85:425-428) for E.coli O157. To reduce the level of background flora, the medium is made selective by the addition of Cefixime and Potassium tellurite. Positive colonies exhibit a mauve colouration enabling easy interpretation amongst blue or colourless colonies of other bacteria.
In recent years there has been an increase in the number of immuno-compromised patients, which has in turn led to an increased rate of infections associated with Candida species. There were 2151 reported cases of candidaemia in 2016 with C.albicans accounting for 42%, C.glabrata for 25%, C.parapsilosis for 9% and C.tropicalis for 3% of infections in England, Wales and Northern Ireland.(1)
COLOREX™ Candida was formulated specifically for the detection and isolation of clinically significant Candida spp. by means of colonial colour and morphology within 48hrs. COLOREX™ Candida allows for the recognition of a minor Candida population within a mixed population as well as the pre-dominant species thereby allowing for a patient specific treatment plan at the earliest possible opportunity. Most bacterial species will be inhibited due to the inclusion of chloramphenicol.
C.albicans – Green colonies
C.tropicalis – Metallic blue colonies
C.glabrata – Mauve to pink colonies
C.krusei – Large fuzzy pink colonies
Definitive identification requires additional testing of isolates (e.g. MALDI-TOF). C.glabrata and C.parapsilosis cannot be readily distinguished on this particular medium. C.dubliniensis will form dark green colonies on COLOREX™ Candida so additional testing is required to confirm presence in the specimen. C.auris isolates will grow on this medium but the colony colour may vary from white to pale purple/pink so further testing will be required to confirm identification.
Primary UTI Opaque
Recent developments in culture media have given rise to the use of chromogenic substrates as a means of differentiating bacteria particularly among the coliform group of organisms. This is one such medium and has been developed with the aim of simplifying the differentiation and presumptive identification of the main organisms usually found in Urinary Tract Infections. Based on the traditional CLED Medium, to prevent the swarming of Proteus spp, two chromogens are present in the medium. One allows the detection of enterococci giving rise to blue colonies whilst the second results in purple colonies of E. coli. Phenylalanine and Tryptophan are also included as indicators of Tryptophan deaminase activity producing brown colonies of Proteus spp. This media is an opaque version to aid differentiation and presumptive identification of the bacteria isolated.
This is a chromogenic medium based on CLED that has been developed to allow differentiation and presumptive identification of organisms typically found in urinary tract infections. Reduced electrolyte concentration prevents swarming of Proteus spp. A sophisticated binary chromogenic system and supplementation with tryptophan allows differentiation of Enterococcus spp. (turquoise colonies), Proteus spp. (clear colonies with a brown halo), Enterobacter spp. (metallic blue colonies), Staphylococcus spp. (white colonies), and E. coli (purple colonies).
Recent developments in culture media have given rise to the use of chromogenic substrates as a means of differentiating bacteria particularly among the Enterobacteriaceae. Colorex™ ESBL (Extended Spectrum Beta-Lactamase) medium has been developed for the isolation of ESBL – producing organisms with the aim of simplifying the differentiation and presumptive identification of the causative organism. It should be noted that other non-ESBL and AmpC isolates will be inhibited on this medium reducing the incidence of false positives. The distinctive colonial colouration of the various species can reduce the need for additional follow up testing allowing many positive results to be issued within 24 hours of receipt of the sample. If necessary an Indole test for confirmation of Escherichia coli and TDA test for Proteus spp. can be performed directly from the medium.
Typical colour reactions are as follows:
Escherichia coli – Red colonies;
Proteus spp., Providencia spp. & Morganella spp. – Clear colonies with a brown halo;
Klebsiella spp., Enterobacter spp, Serratia spp. & Citrobacter spp. – Metallic blue colonies;
Salmonella spp. & Acinetobacter spp. – Clear colonies; Gram +ve bacterial species and yeasts – Inhibited.
ISA sensitivity test agar 25ml
A defined medium suitable for antimicrobial susceptibility testing this medium has been approved for use in the BSAC method. Most organisms will grow on this medium and the very low levels of Trimethoprim and Sulphonamide antagonists means that is not necessary to add Lysed Horse Blood when testing most organisms.
Sorbitol Mac & Cefix./Tell.
Sorbitol MacConkey with Cefixime & Tellurite (CT-Smac)
This is a selective differential medium for the isolation of Escherichia coli 0157:H7. It differs from other MacConkey medium in that Lactose has been replaced by Sorbitol. As Escherichia coli 0157:H7 does not ferment Sorbitol it produces pale translucent colonies whereas most other strains of Escherichia coli are Sorbitol positive and produce pink colonies. The medium is made more selective by the addition of the antimicrobial Cefixime and Potassium Tellurite.
RPMI Medium for E-Test
RPMI Medium is recommended for use in anti-fungal susceptibility testing of yeasts from clinical isolates using the E-Test method. The medium is based on a simple Glucose Agar with added RPMI-1640 Medium (without Sodium Bicarbonate & Phenol Red), which supplies the necessary vitamins and amino-acids, and MOPS (3-(Morpholino)propanesulfonic Acid) Buffer to maintain the medium pH during incubation.
Haemophilus Test Medium (25ml)
This is a medium specifically intended for sensitivity testing of Haemophilus influenzae and Haemophilus parainfluenzae. Based on Mueller Hinton Agar with added Yeast Extract the medium is enriched by the addition of Haemin and NAD (Nicotinamide Adenine Dinucleotide (V Factor)). It contains very low levels of antimicrobial antagonists that allow testing of Sulphonamides and Trimethoprim to be performed with confidence and is recommended by the Clinical and Laboratory Standards Institute (CLSI).
Blood Agar w Neomycin
Columbia Agar Base with 7% Horse Blood & 50mg/L Neomycin
Based on Columbia Agar enriched with 7% Horse Blood this formulation has been modified to include Neomycin, which will inhibit most gram-positive and gram-negative aerobes, making it suitable for use as a selective medium for the isolation of many anaerobes.
Campylobacter Sel. (Preston)
Campylobacter Selective Agar Preston Supplement
This is one of several selective media available for the isolation of Campylobacter spp in clinical, food and environmental laboratories. The medium is enriched with Lysed Horse Blood and made selective by the inclusion of Cefoperazone, to suppress other enteric organisms, and Amphotericin to suppress yeast & fungal growth.
Mueller-Hinton w 5% SB (25ml)
Mueller-Hinton Agar is a defined medium used primarily in Antimicrobial Sensitivity Testing using the disc diffusion technique described by Bauer-Kirby. It is approved as the definitive medium for this purpose by the National Committee for Clinical Laboratory Standards (NCCLS) in USA. It is low in Tetracycline antagonists and although the majority of organisms will grow on the medium without the need for additional supplementation this particular formulation has been enriched with Defibrinated Sheep Blood (5%) making it suitable for use with the more fastidious organisms including many of those that are dependant on Thymine and Thymidine for their growth. The medium can also be used for the isolation of Neisseria spp.
NB: In view of the possible effect on the pH of the medium when used with organisms requiring incubation in a CO2 enriched environment it is essential to include control organisms with the test plates.
BHI & VANCOMYCIN (25ml)
Brain Heart Infusion Agar with Vancomycin
This is a very nutritious general-purpose medium made selective by the inclusion of Vancomycin (6mgs/L) and is therefore suitable for the isolation of Vancomycin resistant organisms. Such as Streptococci and Staphylococci species.
Brain-Heart Infusion Agar
Brain Heart Infusion Agar
This is a very nutritious general-purpose medium suitable for the isolation of most organisms including many fastidious anaerobes. It is particularly recommended for streptococci and neisseria.
FAA with VANC & Nalidixic Acid
Fastidious Anaerobe Agar with 7% Horse Blood, Vancomycin (6mg/L) & Nalidixic Acid (10mg/L)
This is a selective medium for the isolation of gram-negative anaerobes from clinical specimens. The base medium, Fastidious Anaerobe Agar, is complex and includes detoxification agents (Starch & Sodium Bicarbonate), growth enhancing agents (Cysteine, Arginine, Vitamin K, Sodium Succinate, Glucose and pyrophosphate) as well as Haemin to encourage pigment production where appropriate. Sodium Pyruvate is also included to help neutralise Hydrogen Peroxide. The medium is made selective, by the inclusion of Naladixic Acid and Vancomycin and further enriched by the addition of 7% Horse Blood.
Baird Parker Agar
Baird Parker Agar with 5% Egg Yolk Tellurite
Baird Parker Agar is a selective medium for the isolation and presumptive identification of coagulase-positive staphylococci. This medium is used extensively for detecting Staphylococcus aureus in foods, dairy products, and other materials. The medium is made highly selective by the inclusion of Lithium Chloride and Potassium tellurite. The Potassium tellurite inhibits most coliforms and is reduced by staphylococci giving rise to black colonies. Glycine and Sodium Pyruvate are included as growth enhancers while the pyruvate also acts as a neutraliser of toxic peroxides.
NB: Any black colonies (with or without the halo) on this medium must be confirmed as Staphylococcus aureus by further tests (e.g. Coagulase Test or Latex Agglutination etc.)
Czapek Dox Agar
This is a defined medium primarily for the cultivation of fungi and bacteria that are capable of utilising Sodium Nitrate as their sole source of nitrogen. If made more acidic by adjusting to pH 3.5 it can also be used for isolation of acidophilic yeasts. The medium has also been used for the identification of Candida albicans by chlamydospore production.
Tryptone Bile X (TBX) – Glucuronide Agar
Recent developments in culture media have given rise to the use of chromogenic substrates as a means of differentiating bacteria particularly among the coliform group of organisms. This is one such medium and has been developed as a selective medium for the isolation and enumeration of Escherichia coli in food samples. Based on Tryptone Bile Agar it incorporates the chromogenic agent X-glucuronide, which detects glucuronidase activity, the same enzyme as is detected by MUG reagent. Escherichia coli can be differentiated from other coliform organisms by the presence of glucuronidase resulting in the colonies being blue/green while the other coliforms are colourless. For information on the full technical detail as to the functionality of this medium reference should be made to the many publications available.
Columbia CNA w Horse Blood
This is a medium for the selective isolation of Staphylococcus spp. and Streptococcus spp. primarily from clinical specimens. Based on Columbia Agar Base enriched with 7% Horse Blood the medium is made selective by the inclusion of Colistin and Nalidixic Acid to suppress the growth of the majority of Gram negative bacteria.
Colorex Salmonella Plus
Colorex™ Salmonella Plus is a chromogenic media for the isolation and presumptive identification of Salmonella spp, S typhi, S.paratyphi and lactose positive Salmonella from foodstuffs. Any presumptive Salmonella spp. will produce a mauve colouration; other organisms will be blue or colourless in appearance. Cefsulodin is added as a selective agent to inhibit the growth of Pseudomonas and Aeromonas species. Any presumptive isolates must be confirmed using serological and biochemical techniques available to the laboratory. This product meets the requirements of ISO 6579:2002 standard.
Pseudomonas Sel. Agar C.F.C
Pseudomonas Agar Base with 1% Glycerol, Cephalothin, Fucidin & Cetrimide (CFC)
This is a selective medium for the isolation of Pseudomonas spp primarily in food, water and environmental samples. The medium uses Magnesium and Potassium salts to enhance pigment production and is made selective by the addition of CFC supplement. The presence of blue/green or brown pigmentation or fluorescence is indicative of presumptive Pseudomonas spp. It should be noted however that further testing must be carried out to confirm the full identity of the organism.
Potato Dextrose Agar (USP)
This medium is recommended for the detection and enumeration of yeasts and moulds in food and dairy products. It can also be used for the cultivation of fungi although with the prolonged incubation necessary cultures may become overgrown by bacteria. The low pH (5.6) suppresses the growth of most bacteria and the low mineral content ensures good pigment production by fungi where appropriate.
Plate Count Agar (Standard)
Plate Count Agar (APHA) (Standard Methods Agar, Tryptone Glucose Yeast Agar)
This medium is formulated to A.P.H.A. specification and intended for use in food, dairy and water bacteriology to perform Total Viable Counts. The agar is of high gel strength and is therefore suitable for use in pour plate techniques as well as surface inoculation.
Mueller Hinton w 5% DHB & NAD
Mueller-Hinton Agar is a defined medium used primarily in Antimicrobial Sensitivity Testing using the disc diffusion technique described by Bauer-Kirby. It has been approved as the definitive medium for this purpose by the European Committee on Anitmicrobial Susceptibility Testing (EUCAST). This medium contains low levels of thymidine and thymine and controlled levels of calcium and magnesium ions. Additional supplementation of the Mueller Hinton medium using 5% Horse Blood and 20mg/L of Nicotinamide adenine dinucleotide (NAD) makes it suitable for use with the more fastidious organisms such as Streptococcus pneumoniae and Haemophilus influenzae.
Approved by the Clinical Laboratory Standards Institute (CLSI) in USA this medium can be considered as an alternative to Iso-Sensitest Agar for antimicrobial sensitivity testing by disc diffusion methods. It is low in Thymine and Thymidine and is therefore suitable for use in testing Sulphonamides & Trimethoprim without the addition of Lysed Blood.
Milk Agar Cetrimide (W)
This medium is used for the presumptive identification of Pseudomonas aeruginosa from water and environmental samples. Pseudomonas aeruginosa is presumptively identified by the characteristic green pigmentation of the colonies with hydrolysis of casein (clear zones around each colony).
This is a selective medium for the isolation of Legionella spp is used primarily in water and environmental laboratories. The base agar contains Yeast Extract as a source of protein, Charcoal to neutralise growth-inhibiting substances and is supplemented with Ferric Pyrophosphate as a source of iron, L-cysteine hydrochloride and α-ketoglutarate to form amino acid and chelate respectively. ACES buffer is incorporated to maintain the optimal pH for growth. The medium is made selective by the addition of Glycine, Vancomycin & Polymyxin B to inhibit the majority of gram positive and gram negative organisms and Cycloheximide is also included to inhibit yeasts and fungi.
Kanamycin Aesculin Azide Agar
This is a selective medium for the isolation and enumeration of enterococci (Group D streptococci) primarily in food although it has found uses in other areas of bacteriology. The medium is made selective by the inclusion of Kanamycin and Sodium Azide while Aesculin and Ferric Ammonium Citrate act as the indicator system.
G.C. Sel & V.C.A.T.
There are a number of media available for the selective isolation of Neisseria gonorrhoeae of which this is one. Based on the medium developed by Thayer & Martin, it includes Corn Starch to absorb toxic metabolites and is buffered to maintain a neutral pH. The medium is made selective by the inclusion of VCAT (Vancomycin, Colistin, Amphotericin B & Trimethoprim). Vancomycin and Colistin inhibit the growth of the majority of contaminating organisms likely to be present. Trimethoprim is included to reduce the spreading of Proteus spp and Amphotericin B to inhibit yeasts and fungi. Yeast Extract and Glucose are also added as further enrichment along with laked horse blood to ensure an more luxuriant growth of Neisseria gonorrhoeae.
G.C. Sel Agar with L.C.A.T.
There are a number of media available for the selective isolation of Neisseria gonorrhoeae of which this is one. Based on the medium developed by Thayer & Martin, it includes Corn Starch to absorb toxic metabolites and is buffered to maintain a neutral pH. The medium is made selective by the inclusion of LCAT (Lincomycin, Colistin, Amphotericin B & Trimethoprim). Lincomycin and Colistin inhibit the growth of the majority of contaminating organisms likely to be present. Trimethoprim is included to reduce the spreading of Proteus spp and Amphotericin B to inhibit yeasts and fungi. Yeast Extract and Glucose are also added as further enrichment along with laked horse blood to ensure an more luxuriant growth of Neisseria gonorrhoeae.
Mannitol Salt Agar (USP)
A selective medium for the isolation of Staphylococcus aureus. The high level of Sodium Chloride inhibits most other organisms and as most Staphylococcus aureus ferment Mannitol the inclusion of Phenol Red indicator gives rise to yellow colonies. This formulation complies with the requirements of the Harmonised USP/EP/JP. NB: Some strains of coagulase negative staphylococci can give rise to false positive results on this medium It is necessary therefore to confirm the identity of Staphylococcus aureus by other confirmatory tests (e.g. Coagulase test, Latex test etc.)
This is a selective medium for the isolation and differentiation of bile tolerant gram-negative (enteric) and gram-positive (staphylococci and enterococci) organisms and has uses in all areas of bacteriology. It has the disadvantage that many strains of Proteus spp will spread on it and for this reason MacConkey Agar without Salt may be preferred.
Listeria Oxford Agar
One of several media available as a selective identification medium for the isolation and identification of Listeria monocytogenes in food & clinical laboratories. Using Columbia Agar as the base Lithium Chloride is included to inhibit enterococci and Acriflavine to inhibit some other gram positive and gram negative organisms that may be present in such specimens. It is made further selective by the addition of the antimicrobials Cefoxitin, Colistin & Fosfomycin with Amphotericin included to inhibit any yeasts present. Aesculin is present as an indicator since Listeria monocytogenes will hydrolyse it and the associated reaction with the Ferric Ammonium Citrate gives rise to a black precipitate around the colonies.
A selective culture medium for the isolation and differentiation of Corynebacterium diphtheriae types, Hoyle’s medium allows for rapid growth of the organisms and normally 18 hours incubation should be sufficient for a diagnosis. As the medium is highly selective, inoculation should be by rubbing the swab (or other material) over the entire surface of the agar, there is no need to spread the inoculum with a loop indeed doing so can cause the organism to be missed especially when they are present only in small numbers.
C.L.E.D. Agar (Bevis)
CLED Agar (Bevis)
A modification by Bevis of the original CLED medium of Mackey & Sandys. This formulation uses a double indicator system (Andrade’s (Acid fuchsin) and Bromothymol blue) to improve differentiation of Lactose and Non-lactose fermenting organisms. The lack of Sodium Chloride also prevents the swarming of Proteus spp.
Bacitracin Chocolate Agar
Chocolate Agar with 7% Horse Blood & Bacitacin
A highly nutritious medium enriched with Horse Blood, where the blood has been ‘chocolated’ by heating the medium to 70°C. Suitable for the isolation of most pathogens including many fastidious organisms the addition of Bacitracin makes it is particularly suitable for the selective isolation of Haemophilus spp.
MacConkey Agar without Salt
Originally introduced for the isolation and differentiation of Lactose & Non-Lactose Fermenting enteric organisms the medium in this case has been modified to improve the isolation of staphylococci and enterococci. The absence of Sodium Chloride provides a low electrolyte medium that prevents spreading of most Proteus spp. Although recommended for use in the examination of urine samples in clinical laboratories it has uses in Food, Water and Dairy applications.
DNase Agar is used primarily in clinical laboratories to differentiate Staphylococcus aureus from other Staphylococci based on deoxyribonuclease activity. Following incubation of the plate and confirmation of a pure growth of Staphylococci, the surface of the medium is covered with a small quantity of 1M Hydrochloric Acid to precipitate the DNA. Staphylococcus aureus produce DNase enzymes that hydrolyse DNA resulting in a clear area around the colonies, described as being DNase positive, whereas coagulase negative Staphylococci do not produce clearing.
NB: As with most tests of this type a positive result should not be taken in isolation and other appropriate tests, e.g. Coagulase Test, Latex Agglutination etc, should be carried out.
Desoxycholate Citrate Agar (DCA) (Hynes)
One of several media designed for the differential selective isolation of Salmonella and Shigella spp from clinical and environmental samples. Lactose is added to the medium together with Neutral Red indicator to assist in the differentiation of Lactose and Non-Lactose fermenting organisms. The medium is made selective by the inclusion of Sodium Desoxycholate and Sodium Thiosulphate, which will inhibit most gram-positive organisms. The Sodium Thiosulphate is also broken down by the enzyme thiosulphate reductase to form Sodium Sulphite and Hydrogen Sulphide. The Hydrogen Sulphide, if present, will in turn react with the ferric ions to produce a black precipitate of Ferrous Sulphide and give rise to the classical black centre of most Salmonellae. It has been suggested that this medium may be more suitable for secondary post-enrichment isolation while the original formulation is more appropriate for the primary inoculation of samples.
Yersinia Agar (CIN) VHP WRAP
This is a selective medium for the isolation and enumeration of Yersinia spp. in clinical and food samples. It is made selective by the inclusion of Sodium desoxycholate, Crystal violet and the antimicrobials Cefsulodin, Novobiocin and Irgasan. Mannitol is also included which Yersinia ferments giving a colony that produces a ‘Bull’s Eye’ appearance. The majority of other enteric organisms are inhibited but if they do grow they produce a large pinkish colony with an opaque halo.
Originally introduced as an aid to recovery of Shigella spp. XLD is also a first class medium for recovery of Salmonella spp. It differs from other media of this type in that it has less Sodium Desoxycholate as its selective agent. The indicator system is somewhat complex taking advantage of the fermentation or otherwise of three carbohydrates (Lactose Sucrose and Xylose) together with Lysine Decarboxylase and Sodium Thiosulphate as an indication of the presence or absence of Hydrogen Sulphide.
Thiosulphate Citrate Bile Salts Sucrose (TCBS) Agar
TCBS is a selective isolation medium for culture of pathogenic Vibrio spp. from clinical samples. The formulation was developed by Kobayashi, Enomoto, Skazaki and Kuwahara. This medium inhibits most enterobacteriacae for at least 24 hours. For the isolation of Vibrio spp. other than V.cholerae in environmental bacteriology, it is advisable to incubate at the lower temperature range of 20°C – 30°C.
NB – It is not recommended to perform an oxidase test on any presumptive positive isolates directly from TCBS medium.
Slanetz & Bartley
Originally intended as a medium for the enumeration of enterococci in water using Membrane Filtration, this medium has become more popular in many other areas such as food bacteriology. The medium contains Tetrazolium Chloride, which is reduced by enterococci to the insoluble red dye Formazan resulting in dark red colonies of enterococci on the agar. It should be noted that this reaction is not exclusive to enterococci and colonies should be confirmed by additional testing e.g. Aesculin hydrolysis.
Sabouraud Dextrose Agar
This is one of several media available for the selective isolation of yeasts and fungi suitable for use in all areas of Mycology. The low pH (5.6) of the medium is inhibitory to most bacteria and many diagnostic features such as spores and pigmentation are well developed on this medium.
NB: This is a basic medium only and contains no additional supplements.
Mycological Agar (25ml)
A selective medium for the isolation of fungi, particularly dermatophytes from clinical specimens, Mycological Agar is suitable for use in all areas of Mycology. The medium inhibits most bacteria due to the addition of Chloramphenicol which is added to reduce the risk of bacterial contamination when processing material that may be heavily contaminated particularly with Coliforms. Cycloheximide is also added to suppress the growth of yeasts and saprophytic fungi.
Sab. Dex. w Actidione & Chlor.
Sabouraud Dextrose Agar with Chloramphenicol (50mg/L) & Cyclohexamide (Actidione) (300mg/L)
A selective medium for the isolation of fungi, Sabouraud Dextrose Agar is suitable for use in all areas of Mycology. The low pH of the medium inhibits most bacteria however in this formulation Chloramphenicol (50mg/L) is added to further reduce the risk when processing material that may be heavily contaminated particularly with coliforms. Cycloheximide is also added to suppress the growth of yeasts and saprophytic fungi.
Sab Dex with Chloramphenicol
Sabouraud Dextrose Agar with Chloramphenicol (50mg/L)
A selective medium for the isolation of yeasts and fungi, Sabouraud Dextrose Agar is suitable for use in all areas of Mycology. The low pH of the medium inhibits most bacteria, however in this formulation Chloramphenicol (50mg/L) is added to further reduce the risk when processing material that may be heavily contaminated particularly with coliforms.
This is a basic medium for the cultivation of Legionella spp. It is intended primarily for use as a secondary diagnostic medium in conjunction with Legionella Cystine Free Medium (PP0201) for confirmation of a previously isolated organism.
NB: This is a basal medium only and although it will sustain the growth of Legionella spp. It contains no selective supplements. It is therefore not recommended as a means of primary isolations from clinical samples.
This is a medium intended for the cultivation and isolation of Bordetella pertussis & Haemophilus spp. The base medium contains Charcoal and is enriched with 10% Horse Blood. It can also be used as a maintenance or transport medium for these organisms.
Burkholderia cepacia Agar
This is a selective medium for the isolation of Burkholderia cepacia. The base contains Bile Salts and Crystal Violet as selective agents and Ticarcillin and Polymixin B are added as additional supplements to further improve the selectivity particularly inhibition of most Pseudomonas spp.
F.A.A. & Neomycin
Fastidious Anaerobe Agar (FAA) with 7% Horse Blood & Neomycin (75mg/L)
Fastidious Anaerobe Agar is intended as a primary isolation medium capable of supporting most clinically significant anaerobes including fastidious organisms. The formulation is complex and includes detoxification agents (Starch & Sodium Bicarbonate) as well as growth enhancing agents (Cysteine, Arginine, Vitamin K, Sodium Succinate, Glucose and pyrophosphate) as well as Haemin to encourage pigment production in Porphyromonas melaninogenicus. Sodium Pyruvate is also included to help neutralise Hydrogen Peroxide. In this instance the medium is made more selective by the inclusion of 75mg/L of Neomycin to inhibit most enteric organisms and further enriched by the addition of 7% Horse Blood.
Campylobacter Blood Free CCDA
Campylobacter Blood Free CCDA Agar
One of several media formulations available for the selective isolation of Campylobacter spp., primarily C.jejuni and C.coli, which are the leading cause of enteric illness in the UK. Campylobacter spp. can cause mild to severe diarrhoea, usually self-limiting, but some specific serotypes can trigger acute post-infective conditions affecting the peripheral nervous system, such as Guillain-Barré Syndrome. Campylobacter Blood-Free Selective Medium (CCDA) was first described by Bolton. This medium was formulated to replace blood with a combination of charcoal, ferrous sulphate, and sodium pyruvate. Also, in order to improve selectivity, Cefoperazone replaced the Cephazolin utilised in the original formulation. Bolton recommended incubating inoculated plates at 37°C to improve isolation rates but incubation at 41.5°C is recommended for the isolation of the commonly encountered thermophilic species (C.jejuni & C.coli). Yeast and fungal contaminants can be suppressed with the addition of Amphotericin B. Campylobacter Blood-Free Selective Medium (CCDA) is recommended for food testing. Campylobacter Blood-Free Selective Medium with the addition of Yeast Extract and Cefoperazone is used in the Isolation of Campylobacter species from foodstuffs and swabs in the FDA/BAM Method. The product complies with the requirements of ISO 10272-1:2006.
Columbia Agar & Horse Blood
A general purpose medium enriched with 5% Defibrinated Horse Blood, suitable for the isolation of most organisms including many fastidious anaerobes.
Columbia Agar Chocolate
A highly nutritious medium enriched with Horse Blood, where the blood has been “chocolated” by heating the medium to 60°C. Suitable for the isolation of most pathogens including the most fastidious and is particularly useful for the cultivation of Haemophilus spp. and Neisseria spp.
Brilliant Green Modified Agar
Brilliant Green Agar
This medium is intended for use in the isolation of Salmonellae other than Salmonella typhi. Although it can be used as a primary isolation medium it is not recommended for this purpose and is generally used for subculture from selective enrichment media. It should be noted that the medium is highly selective and therefore not suited to the isolation of Salmonella from samples where the numbers may be low.
NB: It is not recommended that this medium be used for the isolation of Salmonella typhi and Shigella spp.
Bacillus cereus (MYP) Agar
Bacillus Cereus (Mannitol Egg Yolk Polymixin – MYP) Agar
Intended for the selective enumeration of Bacillus cereus in food samples the medium uses two reactions (Mannitol fermentation and Lecithinase production) to differentiate Bacillus cereus from other members of the species. As Bacillus cereus is Mannitol Negative the colonies are pink in colour due to the presence of Phenol Red Indicator. Lecithinase production (from the Egg Yolk) is indicated by a white precipitate around the colonies. Polymixin is added as the selective agent to inhibit coliforms.
NB: It should be noted that some Proteus spp and gram positive cocci may grow on this medium.
Bile Aesculin Agar
Bile Aesculin Agar
Bile Aesculin Medium is generally used for the differentiation and presumptive identification of Group D streptococci (enterococci). Enterococci hydrolyse aesculin forming, amongst other products, aesculetin which in turn combines with Ferric ammonium citrate producing a dark brown or black complex. The presence of Bile salts in the medium inhibits gram positive organisms other than enterococci. The medium can also be used for the presumptive identification of certain organisms within the Enterobacteriaceae group such as Klebsiella spp., Enterobacter spp., etc.
Phage Agar is a non-selective medium suitable for the bacteriophage typing of Escherichia coli O157 isolates using the multipoint inoculation technique.
Non-acidified Pyruvate LJ Med
This is an egg-based medium for the isolation and presumptive identification of Mycobacterium spp. Designed for use with NaOH treated samples which are neutralised using known buffering solutions to achieve a pH of 6.8 to 7.0 and which are inoculated directly onto LJ media after concentration by centrifugation. This medium will isolate most common mycobacteria including M.bovis. Based on the original formulation of Lowenstein that was subsequently modified by Jensen, the medium contains pyruvate and egg which provide the required protein and fatty acids. It differs from Lowenstein-Jensen Medium in that Sodium Pyruvate has replaced the Glycerol, which has been demonstrated to be inhibitory to some species, particularly M.bovis. The coagulation of the egg albumin during preparation also provides a solid surface for inoculation purposes.
Malachite green is incorporated into the medium to inhibit contaminating organisms other than the mycobacteria that may still be present in the specimen after decontamination.
Lowenstein-Jensen slopes should be inoculated with pre-treated specimens and incubated at 35-37°C for 8 weeks in 5-10% CO2. Container caps should be left loose for the first week of incubation to allow for circulation of the carbon dioxide as this will help to stimulate growth. Caps should then be tightened to prevent any dehydration of the medium.
Non-acidified Glycerol LJ Med
This is an egg-based medium for the isolation and presumptive identification of Mycobacterium spp., particularly Mycobacterium tuberculosis. Designed for use with NaOH treated samples which are neutralised using known buffering solutions to achieve a pH of 6.8 to 7.0 and which are inoculated directly onto LJ media after concentration by centrifugation.
NB: this media will NOT isolate M.bovis which requires the addition of pyruvate as a growth supplement.This is normally overcome by the inclusion of a pyruvate slope. Based on the original formulation of Lowenstein that was subsequently modified by Jensen, the medium contains glycerol and egg which provide the required protein and fatty acids. The coagulation of the egg albumin during preparation also provides a solid surface for inoculation purposes. Malachite green is incorporated into the medium to inhibit contaminating organisms other than the mycobacteria that may still be present in the specimen after decontamination. Lowenstein-Jensen slopes should be inoculated with pre-treated specimens and incubated at 35-37°C for 8 weeks in 5-10% CO2. Container caps should be left loose for the first week of incubation to allow for circulation of the carbon dioxide as this will help to stimulate growth. Caps should then be tightened to prevent any dehydration of the medium.
Buffered Nitrate Motil Medium
This is a modification of the original Nitrate Reduction Broth which is generally used as one of a series of identification tests for the enterobacteriaceae group of organisms. In addition to allowing the testing of Nitrate Reduction this formulation also contains Agar making it possible to concurrently determine motility. The medium is recommended for use in the confirmatory testing of Clostridium perfringens in water samples. The medium is inoculated by “stabbing” the test organism into the medium, using an inoculating needle or straight wire, and after appropriate incubation motility is demonstrated by diffusion of the organism from the line of inoculation into the medium. The Nitrate Reduction Test is a test for the presence of the enzyme nitrate reductase which, in the presence of an appropriate electron donor, reduces nitrate to nitrite. Following incubation “Nitrate Reagent” is added to the medium and a positive reaction is indicated by the formation of a red colour. For full details of the test method reference should be made to appropriate publications.
Mineral Mod. Glut. Med./DBL St
A broth suitable for the cultivation of bacteria especially members of the Enterobacteriacae genus. This medium allows for the detection of gas when a Durhum tube is incorporated in the medium.
A broth suitable for the cultivation of bacteria especially members of the Enterobacteriacae genus. Which allows the detection of acid & gas when a Durhum tube is incorporated in the medium.
Perfringens Agar Base
This is a base medium to which can be added selective supplements of choice for the presumptive identification and enumeration of Clostridium perfringens in food products using poured plate techniques. Sodium metabisulphite and Ferric ammonium citrate are included in the base and together provide an indicator of sulphite reaction by Clostridium perfringens, which produces black colonies on the medium. It is recommended that this medium be used with an overlay otherwise cultures may not grow as black colonies.
NB: This is a base medium only and contains no selective supplements.
TSB w Novobiocin-20mg/L
Tryptone Soya Broth (Modified) with Novobiocin (20mg/L)
This is a selective enrichment broth for the isolation of Escherichia coli 0157, primarily from food and food products, and is capable of detecting the organisms even when they are present in small numbers. It is also increasingly being used in clinical laboratories when screening faecal samples. Based on Tryptone Soya Broth it is made selective for Escherichia coli 0157 by the addition of bile salts and Novobiocin and is also buffered to maintain the pH during incubation. This medium is generally used in conjunction with selective agar subculture (e.g. Sorbitol MacConkey Agar with Cefixime Tellurite – (CT-SMAC)).
Campylobacter Broth Bolton
This is one of a number of selective enrichment broths that can be used in the isolation of Campylobacter spp from clinical, food and environmental specimens and contains nutrients to aid in the resuscitation of damaged organisms. The medium is enriched with Lysed Horse Blood and made selective by the inclusion of Vancomycin, Cefoperazone, Trimethoprim and Amphotericin B. Following incubation at 37ºC the broth is usually sub-cultured onto an appropriate solid Campylobacter medium.
Tryptone Soya Agar
This is a general-purpose medium supporting a wide range of organisms. It conforms to the requirements of the United States Pharmacopeia for sterility testing of pharmaceutical products as well as being suitable in all areas of bacteriological investigation.