Food / Water / Environmental

Food, Water & Environmental Pre Poured Petri Dishes

E&O manufacture and stock a comprehensive range of high quality standard and bespoke formulations of readytouse plated culture media in several different petri dish sizes and media depths to accommodate all microbial growth requirements. Packaging formats comply with all industry sector regulations.

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  • Bacillius cereus Selective Agar (PEMBA) This is a medium for the selective isolation and enumeration of Bacillus cereus in food samples. It is said to be particularly suitable for the detection of small numbers of Bacillus cereus particularly in the presence of other contaminating organisms. The medium is made selective by the inclusion of Polymixin and Sodium Pyruvate is also present which is said to improve Egg Yolk precipitation and enhance sporulation. As Bacillus cereus is Mannitol Negative the colonies are bluish in colour, due to the presence of the Bromothymol Blue Indicator, with a surrounding precipitate of the same colour due to Lecithinase production (from the Egg Yolk). NB:  It should be noted that some Proteus spp. and gram positive cocci may grow on this medium.
  • 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.
  • 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.)
  • 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.
  • A general purpose medium enriched with 5% Defibrinated Sheep Blood, suitable for the isolation of most organisms including many fastidious anaerobes.
  • 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.
  • This medium is designed for the selective isolation of Campylobacter spp., particularly C. jejuni and C. coli , which are major causes of gastrointestinal infection. Campylobacter Blood Free Agar CCDA was formulated to allow replacement of blood with a combination of charcoal, ferrous sulphate, and sodium pyruvate. Selectivity is achieved through the addition of broad spectrum cefoperazone and amphotericin B to inhibit fungi. Inoculated plates are incubated at 41.5°C to improve growth of the thermophilic species including C. jejuni and C. coli. Campylobacter Blood Free Agar CCDA is recommended for food testing in compliance with the requirements of ISO 10272- 1:2017(1) . It can also be used for isolation of Campylobacter spp. from clincal specimens such as faeces(2,3). 1. ISO 10272-1:2017. Microbiology of food and animal feeding stuffs – Horizontal method for detection and enumeration of Campylobacter spp. – Part 1: Detection method. 2. Public Health England. (2014). Investigations of Faecal Specimens for Enteric Pathogens. UK Standards for Microbiology Investigations. B 30 Issue 8.1. 3. Public Health England. (2018). Identification of Campylobacter species. UK Standards for Microbiology Investigations. ID 23 Issue 3.1.
  • 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.
  • 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.
  • Campylobacter Selective (Skirrow) Agar This is one of several selective media available for the isolation of Campylobacter spp in clinical, food and environmental laboratories. Based on Columbia Agar enriched with Lysed Horse Blood. Polymyxin B, Trimethoprim & Vancomycin are added as the selective agents. Sodium Thiosulphate, Pyruvic Acid and Ferrous Sulphate are also included to enhance the aerotolerance of Campylobacter spp. NB: This medium should be incubated at 42°C to optimise selectivity.
  • 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.
  • 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.
  • 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.
  • 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).
  • A very nutritious general-purpose medium based on Columbia Agar Base enriched with 5% Sheep Blood, suitable for the isolation of most organisms including most fastidious anaerobes of clinical significance. Many workers claim that β-haemolysis is more readily apparent, particularly in group A streptococci, when Sheep Blood is used in place of Horse Blood.
  • Dichloran Rose-Bengal Chloramphenicol (DRBC) Agar Dichloran Rose Bengal Chloramphenicol Agar is based on the formulation described by King et al. It is a selective medium for the isolation and enumeration of yeasts and mould that are of significance in food spoilage. The medium is a modification to Rose Bengal Chloramphenicol Agar and is recommended by the International Standard ISO 21527:2008 part 1.
  • PP0400

    DNase Agar

    DN'ase Medium 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.
  • DNase Agar is used primarily in clinical laboratories to differentiate Staphylococcus aureus from other staphylococci based on deoxyribonuclease activity. Staphylococcus aureus produce DNase enzymes that hydrolyse DNA resulting in a colourless zone around the colonies, described as being DNase positive, whereas coagulase negative staphylococci do not produce clearing. This particular formulation can also be used for Streptococci and Serratia. 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.
  • This medium was initially intended for the selective isolation of Shigella spp. but can also be used for Salmonella spp. primarily from clinical specimens although it has been used in the examination of dairy products. The medium contains high levels of Peptone to counteract some of the toxic effects, particularly on Shigella, of the Bile Salts used to make the medium selective. In addition to Lactose, Sucrose and Salicin are also included allowing for improved differentiation than with Lactose only. The presence of H2S is detected by the reaction between Ammonium Ferric Citrate and Sodium Thiosulphate. A double indicator system of Acid Fuchsin and Bromothymol Blue is helpful in the differentiation process.
  • 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.
  • Legionella Cystine Free Medium is intended for use in conjunction with Legionella CYE Medium (PP0200) as a secondary diagnostic medium for confirmation of a previously isolated organism. Although it contains Ferric Pyrophosphate and α-ketoglutarate it does not contain any L-Cysteine Hydrochloride. NB : This is a base medium only and will not sustain the growth of Legionella spp.
  • 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.
  • 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.
  • 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.
  • 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.
  • This is a selective medium primarily for the isolation of Enterobacteriacae from waters & sewage. This media differs from the original MacConkey formulation in that as well as Bile Salts, Crystal Violet has been included as an additional selective agent. This has the effect of inhibiting gram-positive micrococci.
  • This is a medium for the cultivation of yeasts and moulds. The high carbohydrate content is said to ensure rapid growth while the low pH (5.4) inhibits most bacteria. Malt Extract Agar can also be used for the cultivation of fungi although with the prolonged incubation necessary cultures may become overgrown by bacteria.
  • 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.)
  • Middlebrooks 7H10 Selective Medium is an Agar based medium for the isolation of Mycobacteria spp from clinical specimens. It differs from Middlebrooks 7H11 Agar in that it has a lower concentration of Malachite Green, which is said by some workers to make it more suitable for primary isolation. The medium is complex but includes L-Glutamic Acid, Ammonium Sulphate, Sodium Citrate, Pyridoxine and Biotin as growth factors and Magnesium Sulphate, Ferric Ammonium Citrate as sources of trace ions. Further enrichment is provided by the addition of Oleic Acid, Albumen and Dextrose and it is made selective by the inclusion of Ticarcillin, Polymixin B, Trimethoprim and Amphotericin B. As with egg media Glycerol is included to enhance the growth of the Mycobacteria and Malachite Green is incorporated to provide a colour contrast between the colonies and the medium as well as contributing some inhibitory effect on organisms other than mycobacteria.  
  • 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).
  • PP0670

    Nagler Medium

    Based on Fastidious Anaerobe Agar Base with added Egg Yolk Emulsion, this medium can be used to test Clostridium perfringens for phospholipase production. A zone of opalescence around the colonies is indicative of a positive reaction. It can also be used as an aid to identification of Clostridium perfringens if antitoxin is spread onto half of the plate prior to inoculation (Nagler Reaction).
  • PP0690

    Nutrient Agar

    A basic general-purpose medium suitable for use in the cultivation of the less fastidious organisms particularly those that do not require the addition of blood or other enrichment.
  • This is an established medium, with a neutral pH, used for the enumeration of Yeasts and Moulds
  • PP0005

    PALCAM Agar

    This is a selective differential medium for the isolation of Listeria monocytogenes from food, clinical and environmental specimens.
  • This medium is recommended for the detection and enumeration of yeasts and fungi in a variety of sample types. The low pH (5.6) and addition of streptomycin will ensure that the growth of most bacterial species is inhibited and the low mineral content ensures good pigment production by fungi where appropriate.
  • Chromogenic Coliform Agar (CCA) Chromogenic Coliform Agar (CCA) conforms to the ISO 9308-1 guidelines for the detection, enumeration and isolation of coliforms and more specifically Escherichia coli in water samples by the membrane-filtration technique. The colonial differentiation is provided by the chromogenic substrates, Salmon-GAL and X-glucuronide. Salmon-GAL is used for the detection of β-D-galactosidase enzymatic activity. X-glucuronide is used for the detection of β-D-Glucoronidase enzymatic activity. β-D-galactosidase, expressed by all coliforms, cleaves the Salmon-GAL substrate and producing red/pink coloured colonies. Unlike other coliforms, Escherichia coli leaves both Salmon-GAL and X-glucuronide producing a violet/blue coloured colonies. Tryptophan is used to increase detection reliability by improving the indole reaction. The peptones, sodium pyruvate and sorbitol support bacterial growth and simple recovery of sub-lethal thermally injured coliforms. Sodium di-hydrogen phosphate and di-sodium hydrogen phosphate phosphate buffer the medium and sodium chloride is used to achieve osmotic balance. The selectivity is attained by the addition of Tergitol® 7 as it inhibits the growth of Gram positive bacteria.
  • 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.
  • 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.
  • Pseudomonas Agar Base with 1% Glycerol & CN Supplement A selective medium for the isolation of Pseudomonas aeruginosa the medium is made selective by the inclusion of Cetrimide and Naladixic Acid (CN) supplement to significantly reduce the enteric organisms particularly Proteus and Klebsiella spp. Magnesium and Potassium salts are included to enhance the production of the pigments pyocyanin and fluorescein.
  • A selective medium for the isolation of Pseudomonas spp. primarily in food, water and environmental samples the medium is made selective by the addition of CFC supplement (cetrimide, at a concentration of 10mg/L which is said to allow the growth of all pseudomonads, cephalothin and fucidin). 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.
  • PP1281

    R2A Agar

    R2A medium was developed to determine the bacterial count including heterotrophic bacteria in potable waters during treatment and distribution. This medium has a low nutritional content and therefore requires extended incubation times. It is recommended by the Environmental Agency, Methods for the Examination of Waters and Associated Materials, and Standard Methods for the Enumeration of Water and Wastewater.
  • 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.
  • This is a differential medium for the isolation of Escherichia coli 0157:H7. It differs from other MacConkey media 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 do ferment sorbitol and produce pink colonies.
  • 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.
  • 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.
  • Triphenyltetrazolium Chloride Soya Tryptone (TSAT) Agar Complete Triphenyltetrazolium Chloride (TTC) has been added as an indicator to various media, and recommended by several workers as being helpful in the early recognition and identification of a variety of bacteria including Escherichia coli, Vibrio parahaemolyticus and enterococci. This particular formulation is based on a Tryptone Soya Agar with added Sucrose and is particularly useful when performing counts on food and food product samples. Many of the enterobacteriaceae and enterococci will reduce the TTC to a formazan which colours the colonies deep red making them easier to distinguish and identify. The presence of the Sucrose can also assist in the differentiation of Sucrose fermenting and non-fermenting strains.
  • This is a plate count agar originally suggested by the American public Health Association for the estimation of total viable counts in food and dairy products.
  • This is a general-purpose medium which supports the growth of a wide range of organisms. It is suitable for Phage Typing, Colicine Typing and for testing the X and V requirements of Haemophilus spp as well as many other areas of bacteriological investigation and conforms to the requirements of the United States Pharmacopeia for sterility testing of pharmaceutical products.
  • Violet Red Bile Glucose Agar Violet Red Bile Glucose Agar is a selective medium for the isolation and enumeration of enterobacteriacae in food products. It is a modification of the original Violet Red Bile Agar (PP1150) with the Lactose being replaced with Glucose. As all members of the enterobacteriacae ferment Glucose it allows for a wider range of organisms to be detected. The medium is made selective by the inclusion of Bile Salts and Crystal Violet to inhibit gram-positive and other non-enteric organisms.
  • PP0320

    XLD Agar

    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.