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Traditionally, standard methods for enumeration of heterotrophic bacteria in water have used nutritionally rich media with incubation at 35°C. This may represent only a small percentage of bacteria present in the sample. R2A agar is a nutritionally reduced medium which, when combined with incubation at lower temperatures for longer time periods, results in enhanced recovery of stressed and chlorine damaged organisms from treated waters resulting in higher more realistic bacterial counts. -
Rappaport Vassiliadis (R.V.) Single Component Enrichment Broth This is an alternative to Selenite and Tetrathionate broths, as a selective enrichment broth for the isolation of Salmonellae spp from food, dairy and environmental samples and is claimed by some workers to be superior to both these formulations. It can also be used in clinical bacteriology but care must be taken to ensure that only a light inoculum is used. Malachite Green and Magnesium Chloride are included in the formulation as selective agents due to their ability to inhibit most enteric organisms but allow salmonellae to multiply freely. NB: This media is not recommended for use when salmonella typhi is suspected. -
An osmotically controlled solution for the preparation of suspensions of food samples and for use as a diluent in dilution techniques for bacterial enumeration. The solution may also be used in the sampling of food production apparatus by the rinse and swab method. -
An osmotically controlled solution for the preparation of suspensions of food samples and for use as a diluent in dilution techniques for bacterial enumeration. The solution may also be used in the sampling of food production apparatus by the rinse and swab method. -
Saline (0.85%) is suitable for use in preparation of food samples and/or as a rinse fluid during examination of equipment etc. prior to culture. It can also be used as a general purpose diluent in many areas of the laboratory. -
BM0385 Saline (0.85%) with Beads is used in preparation of tissue specimens for microbiological examination prior to culture. It may also be used as a general-purpose diluent in many areas of the laboratory. Saline (0.85%) is recommended for processing clinical specimens for microbiological examination. The addition of glass beads will allow the specimen to be broken down and, therefore, aiding with the release of microorganisms into the saline for further testing. BM0385 Saline (0.85%) with Beads maintains the osmotic balance of the medium thereby maintaining cell morphology and integrity of bacteria. Glass beads assist with homogenisation of specimens prior to subculturing to primary isolation agar plates and/or enrichment broths. The solution does not interfere with any biochemical reaction and/or antibiotic susceptibility test. -
Saline (0.9%) is suitable for use in preparation of food samples and/or as a rinse fluid during examination of equipment etc. prior to culture. It can also be used as a general purpose diluent in many areas of the laboratory. -
BM0397 Saline Tryptone Water (pH 7.0) is isotonic saline containing 0.1% tryptone that may be used as a general-purpose diluent in many areas of the laboratory. It is recommended by The British Standards Institute (1) and is tested according to the principles of ISO 11133:2014 (2). The product does not interfere with biochemical reactions used to identify organisms, such as indole production.
References
- The British Standards Institution (2015) BS EN 16615:2015 Chemical disinfectants and antiseptics. Quantitative test method for the evaluation of bactericidal and yeasticidal activity on non-porous surfaces with mechanical action employing wipes in the medical area (4- field test). Test method and requirements (phase 2, step 2). Published by BSI Standards Limited.
- International Organization for Standardization (2014) 11133:2014 Microbiology of food, animal feed and water - Preparation, production, storage and performance testing of culture media. Geneva, ISO.
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A medium for the selective enrichment of Salmonellae spp from both clinical and food samples. It is a buffered Lactose Peptone Broth to which Sodium Biselenite is added as the selective agent and Cystine to enhance the recovery of salmonella in low numbers. Subcultures should be made from the top 1/3 of the broth after not more than 24 hours incubation as after this time there is a loss of selectivity. -
BM0360 Selenite F Broth is a medium for the selective enrichment of Salmonella spp. from both clinical and food samples. Following overnight incubation subculture(s) are usually made on to one or more of the many selective enteric solid media. Selenite F Broth is also recommended by the American Public Health Association (APHA) for the examination of food. Subcultures should be made from the top 1/3 of the broth after not more than 24 hours incubation as after this time there is a loss of selectivity. -
BM1841 SIM Medium is a versatile medium that allows for the evaluation of hydrogen sulphide production, indole formation, and motility. These characteristics aid in identifying Enterobacteriaceae, particularly Salmonella and Shigella spp., as well as Clostridium spp.. -
This medium can be used as a screening method for the differentiation of Enterobacteriaceae based on the ability of some species to utilise citrate as a sole source of carbon. It is often used as a screening test for Klebsiella pneumoniae (Positive reaction) while Escherichia coli is negative. Other uses included distinguishing between species of citrate positive Salmonellae (e.g. Salmonella enteritidis) and those that are negative (e.g. Salmonella typhi and Salmonella paratyphi A). The medium is inoculated by stabbing the organism (in pure culture) into the medium. A positive result produces a change of colour from green to bright blue and a negative reaction leaves the colour unchanged. -
This medium is utilised for the transportation and cryopreservation of Streptococcus pneumoniae & Neisseria meningitidis isolates.
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This is a medium that can be used to differentiate between some of the Enterobacteriacae on the basis of four reactions, fermentation of Lactose, Glucose and Sucrose and the production of H2S. For use the medium is inoculated using a pure culture of the test organism which should be smeared onto the surface of the slope and stabbed into the butt of the medium. For details of the many reactions that may arise during the use of this medium reference should be made to one of the many standard textbooks.
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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.
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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. -
BM1436 Tryptone Soya Agar (pH 7.2) is used for a wide range of applications, including culture storage, enumeration of cells, isolation of pure cultures, or general culture. It has been found to be useful in cosmetic testing, water, and wastewater applications. This medium meets the requirements of The British Standards Institution (1) and is tested according to the principles of ISO 11133:2014 (2). and is based on the original formulation described by Leavitt et al. in 1955 (3). In environmental monitoring applications, it is common for plates to be incubated at 30-35°C for bacterial colonies and 20-25°C for mould and fungi (4).
- The British Standards Institution (2015) BS EN 16615:2015 Chemical disinfectants and antiseptics. Quantitative test method for the evaluation of bactericidal and yeasticidal activity on non-porous surfaces with mechanical action employing wipes in the medical area (4- field test). Test method and requirements (phase 2, step 2). Published by BSI Standards Limited.
- International Organization for Standardization (2014) 11133:2014 Microbiology of food, animal feed and water – Preparation, production, storage and performance testing of culture media. Geneva, ISO.
- Leavitt, J., Naidorf, I. and Shugaevsky, P. (1955) Aerobes and anaerobes in endodontics. Part I. The undetected anaerobes in endodontics. Part II. Sensitive culture medium for the detection of both aerobes and anaerobes. NYSDJ, 25, pp.377-382.
4. Anon. (1987) Testing methods for use in quality assurance of culture media. Int. J. Food Microbiol., 5, pp.291-296
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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)). -
Tryptone Water is an alternative medium to Peptone Water and more reliable for the testing of Indole production. The medium has a high content of Tryptophan that many organisms, particularly coliforms, break down to form Indole. After incubation add a few drops of Indole reagent to determine the Indole reaction (Red colour is Positive). -
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 primarily 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. -
Based on Christensen’s Medium this medium is generally used to detect rapid urease activity of Proteus spp although it can be used to detect urease activity of other Enterobacteriaceae. When used for the later purpose it is necessary to increase the incubation time to as long as 48 hours. -
A modification of Christensen’s Medium by Maslen this medium is generally used to detect rapid Urease activity of Proteus spp although it can be used to detect Urease activity of other Enterobacteriaceae including Urease producing Salmonella and Shigella. Unlike Christensen’s Medium when used for the later purpose it is not necessary to increase the incubation time. -
A medium for the enumeration of coliform organisms in food and dairy products. Lactose fermenters produce red/purple colonies often surrounded by a halo of the same colour. Non-lactose fermenters produce pale colonies. Selective agents are Bile salts and crystal violet used to inhibit Gram positive and non-enteric organisms. -
A modification of Violet Red Bile agar designed to give a ‘coliform’ count. In this medium lactose is substituted with glucose. Glucose is fermented by all members of the Enterobacteriaceae thus V.R.B.G.A gives a presumptive Enterobacteriaceae count. Bile salts and crystal violet are used to inhibit Gram positive and non-enteric organisms. The growth of non-fermentative Gram negative bacteria can be suppressed by using the agar overlay method. -
Originally intended for use in surface counting and pour plating techniques in food and dairy products this medium can be used as a general-purpose medium for the cultivation of most non-fastidious organisms.
