-
Letheen broth modified is intended for use in the isolation of microorganisms from cosmetics. The enzymatic digest of animal tissue, enzymatic digest of casein, yeast extract and beef extract act as carbon, nitrogen and vitamin sources in this medium. Sodium chloride maintains the osmotic balance of the medium. The sodium bisulfite and lecithin inactivates quaternary ammonium compounds. Polysorbate 80 must be added to the medium prior to sterilisation. Polysorbate 80 neutralises phenols, formalin, hexachlorophene, and in combination with the lecithin, ethanol. -
Listeria isolation medium (Oxford) is based on the formulation described by Curtis et al. and is used for the isolation and identification of Listeria spp. in food and clinical laboratories. Columbia agar base provides the required carbon, nitrogen and vitamins in the medium. Lithium chloride is included to inhibit enterococci. Aesculin is present as an indicator; Listeria spp. will hydrolyse aesculin and the associated reaction with the ferric ammonium citrate gives rise to a black precipitate around the colonies. Selectivity is enhanced by addition of Listeria Oxford selective supplement (LS0030). This contains acriflavine, cefoxitin, colistin, fosfomycin and amphotericin to inhibit any yeasts present and some other Gram-positive and Gram-negative organisms that may be present in specimens. Related Supplements : LS0030 Listeria Oxford Selective Supplement
-
Lowenstein-Jensen medium is based on the original formulation of Lowenstein that was subsequently modified by Jensen. It is used with fresh egg and glycerol for the isolation and presumptive identification of Mycobacterium spp., particularly Mycobacterium tuberculosis, from clinical samples. L-Asparagine and Potato starch are sources of nitrogen and vitamins in the medium. Potassium hydrogen phosphate and magnesium sulphate enhance organism growth and act as buffers. Sodium citrate and malachite green are selective agents that have inhibitory effects on organisms other than the mycobacteria. Malachite green is also incorporated into the medium to provide a colour contrast between the colonies and the medium. The required addition of egg emulsion provides the fatty acids and protein required for the metabolism of mycobacteria. Glycerol is also added which is said to enhance the growth of Mycobacterium tuberculosis however other strains of mycobacteria, particularly Mycobacterium bovis, may be inhibited by its presence. Subsequently, sodium pyruvate (12.5 g/600ml) may be used as an alternative to glycerol to encourage the growth of Mycobacterium bovis.
-
MacConkey agar No. 3 is a selective medium primarily for the isolation of Enterobacteriacae from waters and 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 organisms. The peptone acts as a nitrogen, carbon and vitamin source. Sodium chloride maintains osmotic balance. Lactose is a carbohydrate and during its fermentation causes a confined pH drop around the bacterial colony. This causes a colour change in the pH indicator, neutral red and bile precipitation.
-
KM0124 MacConkey Agar with Salt is a selective medium for the isolation and differentiation of bile tolerant Gram-negative (enteric) and Gram-positive (staphylococci and enterococci) organisms in all areas of bacteriology. MacConkey Agar with Salt is based on the formulation by MacConkey in 1900. Staphylococcus and Enterococcus spp. are able to grow due to the omission of crystal violet from this formulation. This medium is recommended by the World Health Organisation and the Department of Health for the bacteriological examination of water, and KM0124 is recommended as a differential primary isolation media by the UK Standards for Microbiology Investigations.
-
MacConkey Agar without Salt and Crystal Violet, based on the formulation by Rappaport and Henig, is a differential medium for the isolation and differentiation of lactose and non-lactose fermenting enteric bacteria while also restricting the swarming of Proteus species. KM0011 is recommended as a differential primary isolation media by the UK Standards for Microbiology Investigations, The Microbiology of Drinking Water and tested in accordance with ISO 11133:2014. Related Supplements : LS0189 Cefotaxime Supplement (1mg/L)
-
A selective medium for the enrichment of Enterobacteriaceae and the detection of Escherichia coli in pharmaceutical products. The inclusion of bromocresol purple indicator makes the colour change caused by acid production from the fermentation of lactose easy to read with gas formation. The presence of ox bile helps to suppress the growth of Gram-positive and non-enteric bacterial species. This formulation complies with the Harmonized USP/EP/JP. Nitrogen is supplied by the gelatin peptone whilst lactose serves as the fermentable carbohydrate source. Oxbile is the selective agent helping to suppress Gram-positive organisms and bromocresol purple detects the pH change as a result of the fermentation of lactose.
-
Malt extract is sourced from hydrolyzed vegetal protein. Due to the high concentration of carbohydrate malt extract is particularly suited for the cultivation of yeasts and moulds especially in contaminated dairy products. In microbiological culture media it provides a source of nutrients, protein, and carbon.
-
Malt extract agar is used for the detection, isolation and enumeration yeasts and moulds. The high carbohydrate content of the medium ensures rapid growth of yeasts and moulds. Malt extract and mycological peptone provide the carbon, protein and nutrient sources required by the organisms. The acidic nature of this medium allows for optimal growth of moulds and yeasts while restricting bacterial growth. Malt extract agar can also be used for the cultivation of fungi, although with the prolonged incubation necessary, cultures may become overgrown by bacteria. The selectivity of the medium can be increased by lowering the pH to 3.5-4.0 or by the addition of selective agents such as chloramphenicol. Related Supplements : LS0050 Chloramphenicol Selective Supplement
-
Malt extract broth is used for the cultivation of yeasts and moulds and is commonly used as part of sterility testing protocols. The high carbohydrate content of the medium ensures rapid growth of yeasts and moulds. Malt extract and mycological peptone provide the carbon, protein and nutrient sources required by the organisms. The acidic nature of this medium allows for optimal growth of moulds and yeasts while restricting bacterial growth.
-
KM0031 Mannitol Salt Agar is a selective medium for the isolation of Staphylococcus aureus from clinical samples, food, cosmetics and water samples. Chapman showed that adding a higher level of sodium chloride to Mannitol Salt Agar allowed for the recovery of pathogenic staphylococci and inhibits most organisms. Coagulase positive staphylococci (e.g., S. aureus) produce yellow colonies and a surrounding yellow medium while coagulase negative staphylococci produce red colonies and no colour change of the phenol red indicator. The medium conforms to the requirements of the Harmonised EP/USP/JP, is recommended as a primary isolation media by the UK Standards for Microbiology Investigations and tested in accordance with ISO 11133:2014 and Clinical and Laboratory Standards Institute. This medium is also included in the Bacteriological Analytical Manual for cosmetics testing.
-
Formulated to ISO 6887-1, Maximum Recovery Diluent (MRD) is a diluent designed to maintain organisms by protecting the cells from unnecessary physiological shock that may occur using other aqueous solutions. MRD is used extensively in food and environmental testing. The low level of peptone provides a protective effect but does not allow for multiplication during the short residence time in the diluent, 45 minutes. The sodium chloride prevents osmotic shock as the sample is initially diluted.
-
Meat peptone is sourced from hydrolyzed proteins of animal tissue. This peptone consists of soluble amino acids and peptides that provide readily available nitrogen and other essential growth factors. It is primarily used for the cultivation of fastidious and non-fastidious microorganisms in microbiological culture media.
-
Originally intended for enumeration of coliforms in water samples, a medium containing glutamic acid was devised by Folpmers and further developed by Gray as a potential replacement for MacConkey Broth. Later, Gray modified the medium to incorporate a variety of minerals promoting improved lactose fermentation by coliforms and Escherichia coli. Minerals Modified Glutamate Medium is suitable for the enrichment of low levels of coliforms and recovery of chlorine-damaged bacteria.
Minerals Modified Glutamate Medium is recommended by the Standing Committee of Analysts and International Organization for Standardization. It is tested in accordance with ISO 11133:2014.
-
KM0183 Mueller Hinton Agar is used as a base to make various media for antimicrobial susceptibility testing by the disk diffusion method as described by Bauer-Kirby. First described by Mueller and Hinton, Mueller Hinton Agar has been approved as the definitive medium for antimicrobial susceptibility testing by European Committee on Antimicrobial Susceptibility Testing (EUCAST), Clinical and Laboratory Standards Institute (CLSI) and is compliant with ISO16782:2016. KM0183, when prepared as unsupplemented Mueller Hinton Agar, is suggested by EUCAST and CLSI for non-fastidious organisms such as Enterobacterales, Pseudomonas spp., Stenotrophomonas maltophilia, Acinetobacter spp., Staphylococcus spp., Enterococcus spp., Aeromonas spp., Achromobacter xylosoxidans, Vibrio spp., Bacillus spp. and Burkholderia pseudomallei. KM0183, when prepared supplemented with 5% horse blood and nicotinamide adenine dinucleotide (NAD), is suggested by EUCAST and CLSI for fastidious organisms such as Streptococcus pneumoniae, Streptococcus groups A, B, C and G, Viridans group streptococci, Haemophilus influenzae, Moraxella catarrhalis, Listeria monocytogenes, Pasteurella multocida, Campylobacter jejuni and coli, Corynebacterium spp., Aerococcus sanguinicola and urinae and Kingella kingae. Additionally, according to the UK Standards for Microbiology Investigations, when supplemented appropriately, Mueller Hinton Agar can be used in the process of identifying Haemophilus species and the HACEK group of organisms and Helicobacter species from clinical specimens. Related Supplements : LS0005 NAD Supplement (20mgs/L), Defibrinated Horse Blood
-
This is a selective enrichment broth for the isolation of Salmonella spp. primarily from food and food product samples and conforms to the requirements ISO 6579:2002. It can however be used in other areas including clinical and environmental specimens. Salmonella spp. reduce tetrathionate and will proliferate in the medium whilst most other enteric organisms are inhibited. Unlike the older traditional tetrathionate broth the addition of novobiocin (40 mg/l) improves the inhibition of Proteus spp. Immediately prior to use it is necessary to add 20 ml/l of 2% iodine/iodide solution (BM0946). Once the iodine/iodide solution has been added the medium should be used immediately and cannot be stored for future use. NB: As this is an opaque medium, the turbidity of the broth alone cannot be used as an indication of growth. Related Supplements : LS0024 Novobiocin Supplement (20mgs/L)
-
Mycological agar is a selective medium for the isolation of pathogenic fungi, particularly dermatophytes, from clinical specimens. Enzymatic digest of soybean meal provides the required carbon, nitrogen and vitamins. Glucose is an energy source for the metabolism of fungi. The addition of chloramphenicol further reduces the risk of bacterial contamination when processing material that may be heavily contaminated with coliforms. Cycloheximide should also be added (0.4g/L) to suppress the growth of commensal yeasts and saprophytic fungi.
-
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. When used to prepare agar slopes or agar butts, the medium can be used to maintain control organisms. The peptone provides the required carbon, nitrogen and vitamins. Sodium chloride maintains osmotic balance.
-
A general-purpose medium for the cultivation of organisms that are less fastidious in their nutritional requirements. The beef extract, peptone and yeast extract act as carbon, nitrogen and vitamin sources in this medium. Sodium chloride maintains osmotic balance.
-
Nutrient Broth No.2 is used for the cultivation of fastidious pathogens and other microorganisms. This general use medium, rich in nutrients, allows the growth of bacteria when there is a low level of cells. The medium is particularly suitable as a secondary growth medium for staphylococci to be tested for coagulase production and also be used for sterility testing of aerobic organisms. Beef extract and peptone provide the required carbon, nitrogen and vitamins. Sodium chloride maintains osmotic balance.
-
O-F Medium is used for the determination of oxidative and fermentative metabolism of carbohydrates by Gram-negative bacilli (1). This is on the basis of the acid reaction in either the open or closed system that has been covered with sterile paraffin oil. Changes in the covered agar are considered to be due to true fermentation, while changes in the open tubes are due to the oxidative utilization of the carbohydrate present. O-F Base Medium requires the addition of the specific carbohydrate being investigated. The enzymatic digest of casein provides the required nitrogen, carbon and vitamins in the media. Sodium chloride maintains the osmotic balance. Di-potassium hydrogen phosphate acts as a buffer and bromothymol blue is a pH indicator. The agar is a solidifying agent. Reference (1) Hugh, R. and Leifson, E.J. 1953. Bacteriol. 66:24-26.
-
Palcam agar is a selective differential medium for the isolation of Listeria monocytogenes from food, clinical and environmental specimens. The Columbia peptone mix and starch provide the required carbon, nitrogen and vitamins. Glucose is a fermentable carbohydrate. Differentiation of Listeria spp. from enterococci and staphylococci occurs through aesculin hydrolysis and mannitol fermentation. Listeria monocytogenes will hydrolyse aesculin and the associated reaction with the ferric ammonium citrate gives rise to a brown/black precipitate around the colonies. Listeria spp. do not however ferment mannitol. Mannitol fermentation is seen through a colour change of the colony or the area around the colony from red to yellow due to the production of acidic end products. Phenol red is the pH indicator in the medium. Lithium chloride is included to inhibit enterococci. The associated Palcam selective supplement, LS0038, contains polymyxin B, acriflavine and ceftazidime to inhibit other Gram-positive and Gram-negative organisms that may be present in specimens. Related Supplements : LS0038 PALCAM Selective Supplement
-
Peptone water is a general-purpose medium that supports thecultivation of non-fastidious organisms. This non-selective medium can be used a basal medium for biochemical tests such as carbohydrate fermentation and production of indole. Tryptone and peptone act as sources of carbon, nitrogen and vitamins in this medium and sodium chloride maintains osmotic balance.
-
Phosphate-buffered saline (PBS) is a buffer solution used in biological research. It is a water-based salt solution containing sodium phosphate, sodium chloride and, in some formulations, it contains potassium chloride and potassium phosphate. The osmolality and ion concentrations of the solutions match those of the human body (isotonic) and are non-toxic to most cells. This balanced salt solution is issued to meet the requirements of those tissue culture workers who use the Dulbecco Solution with and without calcium and magnesium.
-
Plate Count Agar is formulated to the A.P.H.A. specification developed by Buchbinder et al. This medium is intended for use in food, dairy and water bacteriology to perform Total Viable Counts. Tryptone and yeast extract provide the required carbon, nitrogen and vitamins. Glucose is a fermentable carbohydrate.
-
Potato dextrose agar 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. This medium meets the requirements of the Harmonised USP/EP/JP.(1,2&3) REFERENCES (1) United States Pharmacopeial Convention. 2007. The United States pharmacopeia, 31st ed., Amended Chapters 61, 62, 111. The United States Pharmacopeial Convention, Rockville, MD. (2) Directorate for the Quality of Medicines of the Council of Europe (EDQM). 2007. The European Pharmacopoeia, Amended Chapters 2.6.12, 2.6.13, 5.1.4, Council of Europe, 67075 Strasbourg Cedex, France. (3) Japanese Pharmacopoeia. 2007. Society of Japanese Pharmacopoeia. Amended Chapters 35.1, 35.2, 7. The Minister of Health, Labor, and Welfare.
-
KM0058 Primary Listeria Agar is a selective medium for the isolation, enumeration and presumptive identification of Listeria species and L. monocytogenes from food and environmental samples. Listeria monocytogenes is commonly found in soil, sewage, and faeces. It is difficult to eradicate, and can cause serious food poisoning; therefore, L. monocytogenes is frequently tested for in food processing facilities to avoid contamination. Contamination can occur at all steps of the food manufacturing chain from raw materials to point of consumption. Primary Listeria Agar is used for the detection and presumptive identification of Listeria spp. and the specific differentiation of L. monocytogenes. Based on the method of Ottaviani et al (1 2), this medium allows detection and enumeration of Listeria spp. as early as 24 hours. Primary Listeria Agar is recommended by ISO 11290-1:2017 (3) and ISO 11290-2:2017 (4) and tested in accordance with ISO 11133:2014 (5). References:- Ottaviani, F., Ottaviani, M., and Agosti M. (1997) Differential agar medium for Listeria monocytogenes. Quimper Froid Symposium Proceedings, P6 ADRIA Quimper, France, 16-18 June.
- Ottaviani, F., Ottaviani, M.G., and Agosti, M. (1997). Esperienze su un agar selettivo e differenziale per Listeria monocytogenes. Industrie Alimentari, 36: 888-889.
- International Organization for Standardization (2017) 11290-1:2017 Microbiology of the food chain – Horizontal method for the detection and enumeration of Listeria monocytogenes and of Listeria spp. – Part 1: Detection method. Geneva, ISO.
- International Organization for Standardization (2017) 11290-2:2017 Microbiology of the food chain – Horizontal method for the detection and enumeration of Listeria monocytogenes and of Listeria spp. – Part 2: Enumeration method. Geneva, ISO.
- 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.
-
Primary Membrane Lactose Glucuronide Agar (mLGA) is used for the differentiation and enumeration of Escherichia coli and other coliforms through a single membrane filtration technique. The peptone and yeast extract provide the required nitrogen, carbon and vitamins. Sodium pyruvate protects injured cells enhancing recovery and growth of coliforms. Sodium lauryl sulphate is a selective agent that inhibits Gram-positive organisms. Lactose is a fermentable carbohydrate and phenol red is a pH indicator. Lactose fermentation will result in yellow colonies. X-glucuronide is a chromogenic substrate which can be cleaved by the enzyme ß-glucuronidase present in E. coli. This results in a blue colony, but in combination with lactose fermentations colonies will appear green. NB: Prepared plates stored at 28°C may show formation of surface crystals which will disappear when plates are warmed to >20°C Related Supplements :
-
KM0007 Primary UTI Agar is a chromogenic agar that has been developed to allow differentiation and presumptive identification of organisms typically found in urinary tract infections. Urinary Tract Infections (UTI’s) account for 35-40% of all hospital acquired infections in the UK. Gram negative aerobic bacteria are responsible for a considerable proportion of UTI’s with Escherichia coli isolation rates at 80-90% of first-time infections. Various other opportunistic bacterial species can cause UTI’s. KM0007 may be used as a chromogenic medium for the quantification and presumptive identification of bacteria in urine from clinical samples in line with the UK Standards for Microbiology Investigations and tested in accordance with the principles of ISO 11133:2014. Related Supplements : SHS500 Sterile Horse Serum 500ml
-
KM0079 Pseudomonas Agar Base with the addition of supplements, is a selective medium for the isolation of Pseudomonas species primarily from clinical, food, water, and environmental samples. The medium can be made selective for Pseudomonas aeruginosa by the addition of E&O LS0006 Pseudomonas Selective Cetrimide and Nalidixic Acid Supplement which complies to ISO 16266:2006 and ISO 11133:2014. Alternatively, the medium can be made selective for Pseudomonas species by the addition of E&O LS0026 Pseudomonas CFC Selective Supplement which complies to ISO 13720:2010 and can be used as a primary isolation medium according to Public Health England’s UK Standards for Microbiology Investigations. Identification is achieved using the unique ability of P. aeruginosa to synthesise the iron chelating pigments pyoverdin and pyocyanin which combine to produce the characteristic green colonies of Pseudomonas aeruginosa. Production of these pigments is stimulated by the presence of magnesium and potassium ions in the medium. The presence of blue/green or brown pigmentation or fluorescence is indicative of presumptive Pseudomonas species. It should be noted however that further testing must be conducted to confirm the full identity of the organism.
-
R2A agar is used for the enumeration and cultivation of bacteria from drinking water. R2A agar developed by Reasoner and Geldreich is a low nutrient medium that can used in pour plate, spread plate, and membrane filtration methods for heterotrophic plate counts. In combination with a lower incubation temperature and longer incubation period R2A agar stimulates the growth of stressed and chlorine-tolerant bacteria. Traditionally nutritionally rich media have been used for this purpose but these media support the growth of fast-growing bacteria and may suppress slow growing or stressed bacteria found in treated water. Enzymatic digest of casein, proteose peptone, acid hydrolysate of casein and yeast extract provide the required nitrogen, carbon and vitamins. Glucose is a fermentable carbohydrate. Dipotassium hydrogen phosphate is a buffering agent. Magnesium sulphate is a source of divalent cations and sulphate. Starch and sodium pyruvate aid in the recovery of stressed organisms.
-
Rappaport-Vassiliadis Soya Broth is used for the enrichment and selective isolation of Salmonella spp. This medium is a modification of the original formulation by Rappaport et al. and has been formulated to exploit the full characteristics of Salmonella spp. These characteristics include the ability to survive at relatively high osmotic pressure, to multiply at low pH values and greater resistance to malachite green. This formulation also has the correct amount of magnesium chloride as previous formulations did not take into account the volume of displacement caused by dissolving large amounts of magnesium chloride in water. This formulation has been shown to be superior to tetrathionate broth and selenite broth for the isolation of Salmonella spp. from meat products. Soya peptone provides the required carbon, nitrogen and vitamins. Potassium dihydrogen phosphate and di-potassium hydrogen phosphate act as buffers. Magnesium chloride raises the osmotic pressure in the medium. Malachite green is an inhibitory substance. NB: This formulation is very hygroscopic and will produce a slight exothermic reaction when mixed with water.
-
KM0003 Sabouraud Dextrose Agar powder is a general-purpose, non-selective medium which is used for the isolation of yeasts and moulds from clinical, food, pharmaceutical and cosmetic samples. Sabouraud Dextrose Agar is a modification of a medium originally described by Sabouraud. The fungi maintain their typical cultural appearance and thus may be readily identified according to the standard macroscopic characters described by Sabouraud. The formulation conforms to European, United States and Japanese Pharmacopeia requirements. This medium complies with ISO 11133:2014, where it is described as the main reference medium to carry out quantitative testing on culture media intended for fungi. Sabouraud Dextrose Agar is recommended by the UK Standards for Microbiology Investigations for various purposes, including as a standard, supplementary or optional medium. Related Supplements : LS0050 Chloramphenicol Selective Supplement
-
Sabouraud liquid medium USP is used in sterility testing for the detection of moulds, yeasts and acidophilic microorganisms in pharmaceutical products. This medium is also used for non-sterile testing and for the determination of fungistatic activity. Sabouraud liquid medium USP conforms to the USP and Harmonised Pharmacopeia. The peptic digest of animal tissue and pancreatic digest of casein provides the required nitrogen, carbon and vitamins. The high concentration of dextrose is included as an energy source and in tandem with the acidic pH (5.6) facilitates the growth of fungi whilst providing limited selective properties.
-
This is a selective medium for the isolation of Salmonella spp. and Shigella spp. from clinical specimens and food samples. SS agar is a modification of the original DCA medium described by Leifson. The formulation for SS agar was later modified to improve the growth of Shigella spp. SS agar modified differs from SS agar in that it has an alternation to the bile salts mixture, peptone, pH value, and total g/litre. The peptone provides the required carbon, nitrogen and vitamins. Lactose is a fermentable carbohydrate and neutral red is a pH indicator. Sodium thiosulphate and ferric citrate are used to detect hydrogen sulphide production indicated by the black centred colonies of hydrogen sulphite positive organisms. Bile salts, sodium citrate and brilliant green inhibit Gram-positive bacteria and a number of different coliform bacteria.
-
Selenite cystine broth is a modification of selenite F broth and is for the selective enrichment of Salmonellae spp. from clinical, food and environmental specimens. The peptone acts as a nitrogen, carbon and vitamin source. Lactose is a fermentable carbohydrate and sodium phosphate is a buffer. L-cystine is used to enhance the recovery of Salmonellae spp. in low numbers. The medium is made selective by the addition of sodium biselenite (KM8021). Following overnight incubation subculture(s) are usually made on to one or more of the many selective enteric solid media.
-
Developed by Leifson, selenite F broth is a medium for the selective enrichment of Salmonella spp. from both clinical and food samples. The peptone acts as a nitrogen, carbon and vitamin source. Lactose is a fermentable carbohydrate and sodium phosphate is a buffer. The medium is made selective by the addition of sodium biselenite (KM8021). Following overnight incubation subculture(s) are usually made on to one or more of the many selective enteric solid media.
-
Selenite mannitol broth is a modification of selenite broth and is for the selective enrichment of Salmonellae spp. from clinical, food and environmental specimens. Comparisons have shown that mannitol selenite broth is better than other enrichment broths for the isolation of Salmonellae spp. The peptone acts as a nitrogen, carbon and vitamin source. Mannitol is a fermentable carbohydrate and sodium phosphate is a buffer. The medium is made selective by the addition of sodium biselenite (KM8021). The fermentation of mannitol by Salmonellae spp. is said to correct the alkaline pH swing which can occur during incubation. Following overnight incubation subculture(s) are usually made on to one or more of the many selective enteric solid media.
-
Sheep Blood Agar Base has been developed to provide a nutrient rich medium compatible with sheep blood for the cultivation of many bacteria, especially fastidious Streptococcus spp., without affecting haemolytic reactions. Alternative culture mediums, such as Blood agar base No. 2, can results in mixed haemolytic reactions for some Streptococcus spp. This is thought to occur due to the trace amounts of fermentable carbohydrates in yeast extract and the physiological difference between sheep and horse blood. The tryptone, peptone, and yeast extract provide the required nitrogen, carbon and vitamins in the medium. Sodium chloride maintains the osmotic balance. Related Supplements : LS0008 Staph/Strep Selective Supplement
-
For in vitro diagnostic use. KM0159 SIM Medium is a multi-purpose medium for the differentiation of Enterobacteriaceae. This is best described as a multi-purpose medium for the differentiation of Enterobacteriaceae that combines three individual tests into a single medium (hydrogen sulphide production, indole formation and motility). The presence of motility is apparent by the organism tracking out from the line of inoculation and often turning the medium turbid. Non-motile organisms generally grow within the stab line leaving the surrounding medium clear. H₂S positive organisms turn the medium black due to the formation of hydrogen sulphide in the presence of the sodium thiosulfate and ferric ammonium citrate often making it difficult to determine the other parameters. Indole production is tested for by layering a small amount of Indole Reagent (Kovac’s) onto the surface of the medium. A positive result is indicated by the formation of a pink colour at the interface of the reagent and the medium. The enzymatic digest of casein and enzymatic digest of animal tissue provide the required carbon, nitrogen, and vitamins in this medium. Ferric ammonium citrate and sodium thiosulfate are used to detect hydrogen sulphide production. The low concentration of agar allows for a semisolid media which is used for motility detection.
-
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. Species that metabolize citrate as their sole source of carbon and ammonium as the sole source of nitrogen cause an increase in alkalinity of the medium resulting in a colour change from green to blue due to the presence of the pH indicator bromthymole blue.
-
This medium was originally described by Slanetz and Bartley(1) for the enumeration of enterococci from water samples using membrane filtration. The medium has also become useful as a direct plating medium. Tryptose and yeast extract provide the required carbon, nitrogen and vitamins. Glucose is a fermentable carbohydrate. The di-potassium hydrogen phosphate acts as a buffer. Selectivity is achieved through the addition of sodium azide which is used to suppress the growth of Gram-negative organisms. 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.
-
Sorbitol MacConkey agar is a differential medium for the isolation of Escherichia coli 0157:H7 based on the formulation by Rappaport and Henig. It differs from other MacConkey mediums 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. Although it should be noted that colonies that are sorbitol positive can revert and possibly be mistaken as sorbitol negative. Tryptone and meat peptone provide the required carbon, nitrogen and vitamins. Sorbitol is a fermentable carbohydrate and neutral red is a pH indicator. Bile Salts no.3 and crystal violet are selective agents and together inhibit Gram-positive cocci. Sodium chloride maintains the osmotic balance. If required, the selectivity of the medium may be increased by the addition of cefixime (0.05mg/L) and potassium tellurite (2.5mg/L). Related Supplements : LS0013 Escherichia coli 0157 Selective Supplement
-
Soy peptone is manufactured from the enzymatic hydrolysis of soybean. This product provides a good source of nitrogen, carbohydrates, and vitamins. It is recommended for use in microbiological media for the detection and isolation of a wide variety of bacteria and fungi.
-
Thiosulphate Citrate Bile Salts Sucrose (TCBS) Agar is a selective isolation medium for culture of pathogenic Vibrio spp. from clinical and food samples. The formulation was developed by Kobayashi et al. which was modified from Nakanishi’s formulation. Vibrio species are most widely recognized for their role in human intestinal infections and cholera worldwide. Thiosulphate Citrate Bile Salts Sucrose (TCBS) Agar is recommended by the FDA BAM, the UK Standards for Microbiology Investigations, and complies with the standard laid out by ISO 21872.
-
Triple sugar iron agar is used to differentiate between some of the enterobacteriacae on the basis of four reactions: fermentation of lactose, glucose and sucrose and the production of hydrogen sulphide. Beef extract, yeast extract and peptone provide the required nitrogen, carbon and vitamins. Lactose, sucrose and glucose are carbohydrates. Acid production from their fermentation is detected by the phenol red pH indictor. Sodium thiosulphate is reduced to hydrogen sulphide which is detected by the ferric citrate indicator. Sodium chloride maintains osmotic balance.
-
Tryptone is obtained by pancreatic digestion of casein. Casein is the main protein of milk and is a rich source of amino acid and nitrogen. This product can be used in preparing microbiological culture media providing nitrogen, vitamins, minerals and amino acids. Due to the high tryptophan content in tryptone it can be used in detecting indole production.
-
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 without the need for membranes or pre-incubation. Based on the formulation of Tryptone Bile Agar it incorporates a chromogenic substrate, X-Glucuronide, to detect the ß-glucuronidase enzyme which is specific for the majority of E. coli strains. Approximately, 3-4% of E. coli are glucuronidase negative including E. coli O157.(1) The advantage of the chromogenic substrate is that the reaction is concentrated within the colony resulting in distinctive blue/green colonies of E. coli while the other coliforms produce cream colonies. The tryptone provides the required carbon, nitrogen and vitamins. Bile salts No.3 is a selective agent against Gram-positive bacteria. X-glucuronide is a chromogenic substrate. Agar is solidifying agent.
-
Tryptone Soya Agar is used for a wide range of applications, including culture storage, enumeration of cells, isolation of pure cultures, or simply general culture. It has been found to be useful in cosmetic testing, water, and wastewater applications. Tryptone Soya Agar may be used to determine X and V factor requirements of Haemophilus species; sterility testing; and environmental monitoring within pharmaceutical cleanrooms and sterile facilities. This medium meets the requirements of the Harmonized USP/EP/JP and is based on the original formulation described by Leavitt et al. in 1955. Tryptone Soya Agar is recommended as a reference medium when testing selective media, to measure the degree of inhibition. 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. Tryptone Soya Agar will support the growth of both aerobic and anaerobic organisms depending on incubation conditions. KM0024 unsupplemented is recommended by the World Health Organization, UK Standards for Microbiology Investigations, International Organization for Standardization and is tested in accordance with ISO 11133:2014. This medium is also included in the Bacteriological Analytical Manual for cosmetics testing. UK Standards for Microbiology Investigations also call for Tryptone Soya Agar supplemented with 5% sheep blood (E&O DSC) for aid in the identification of Bordetella species from clinical specimens. The addition of defibrinated animal blood to the base medium, promotes the growth of most fastidious organisms and presumptive identification can be made based on haemolytic reactions. It should be noted that the haemolytic patterns of isolates may vary with the source of animal blood. Addition of selective agents allows isolation and presumptive identification of specific species or groups of organisms. Related Supplements : Defibrinated Sheep Blood, Defibrinated Horse Blood
-
A general purpose and nutritious medium for the non-selective enrichment of non-fastidious and some fastidious organisms. Tryptone and soy peptone are the nitrogen and vitamin source in the medium. Glucose is the carbon energy source that facilitates organism growth and sodium chloride maintains osmotic balance. Di-potassium hydrogen phosphate is a buffering agent to prevent auto-sterilisation due to acid production during the growth of some organisms. Tryptone Soya Broth is also commonly referred to as Soybean-Casein Digest Medium or Tryptic Soya Broth and is abbreviated as TSB. TSB conforms to the Harmonized United States Pharmacopoeia (USP), European Pharmacopoeia (EU), and Japanese Pharmacopoeia (JP).
