Dermatophyte is a medical term used to designate a particular group of fungi that infect the skin, hair and nails of humans and animals, causing various skin infections commonly known as “tineas.” Any filamentous fungus isolated from culture samples of skin, hair and nails must be evaluated to determine the presence of dermatophytes. The dermatophytes are divided into three genera: Microsporum, Trichophyton and Epidermophyton, on the basis of their microscopic morphological differences and modes of sporulation. Species of these genera can be divided into three types by their normal habitat: Anthropophilic, are found only in human hosts and are transmitted from person to person; zoophilic are found in animals but can be transmitted to humans and geophilic, which can be found in the ground and may infect humans and animals. Dermatophyte Selective Agar was proposed in 1969 by Taplin and colleagues for the isolation and presumptive identification of pathogenic dermatophytes. The medium contains a plant peptone providing carbon and nitrogen required for growth, while dextrose provides the energy source needed for metabolism. Cycloheximide inhibits saprophytic fungi that may be present in the sample, without affecting the growth of dermatophytes. Gentamicin is an antibiotic that acts on gram-negative bacteria, (including Pseudomonas) and Chlortetracycline is a broadspectrum antibiotic acting on both gram-positive and gram-negative bacteria. This mixture of antimicrobials partially inhibits the growth of bacteria, yeasts and moulds that can contaminate samples and does not affect or has little effect on the growth of dermatophytes. In addition, the medium includes a pH indicator, phenol red, which is yellow-orange in acid medium and red in alkaline medium. The growth of most dermatophytes results in the production of alkaline metabolites that cause the indicator to change from yellow to red, but there are non-pathogenic fungi (nondermatophytes) that cause a colour change. Also there are some strains of microsporum that grow without altering the appearance of the medium. These other organisms that manage to grow in this medium can be recognized as non-dermatophytes both by their colour and colony morphology. The bacteria and few yeasts that may develop produce typically creamy white colonies. Saprophytic contaminants that sometimes cause colour change in the medium can be disregarded if they produce blackish-green coloured hyphae, since dermatophytes always produce white aerial hyphae. However, as the final identification of dermatophyte is the microscopic observation of sporangia and verification of colour on the reverse of the colony, it is recommended that along with the Dermatophyte Selective Agar another medium for fungi e.g. Sabouraud Agar (with or without inhibitors) is inoculated simultaneously in order to verify these characteristics. Thus, DTM is used as an isolation and presumptive identification medium and Sabouraud as an isolation and confirmation medium.

DESCRIPTION Glucose Salt Teepol Broth is a selective enrichment medium used for the enumeration of V. parahemolyticus from seafoods by the most-probable-number (MPN) technique.

PRINCIPLE Peptone and meat extract provide amino acids, nitrogen, carbon, minerals, vitamins and minerals which support the growth of microorganism. Glucose is the fermentable carbohydrate. The high concentration of sodium chloride helps for the better enrichment of halophilic V. parahemolyticus. Methyl violet is the pH indicator. Supplementation with Teepol serves to inhibit the growth of gram-positive organisms.

PREPARATION Suspend 48.0 g of powder in 1 liter of deionized or distilled water. Add Teepol to obtain a concentration of 4 g/l in the complete medium. Mix well. Sterilize by autoclaving at 121°C for 15 minutes. Distribute into final containers.

Principles and uses Trypticasein Soy Broth Modified with Novobiocin (mTSB) is recommended by ISO 16654 for the enrichment of E.coli O157:H7. Casein peptone and soy peptone provide nitrogen, vitamins, minerals and amino acids essential for growth. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Dipotassium phosphate acts as a buffer system. Glucose is the fermentable carbohydrate providing carbon and energy. Bile salts and Novobiocin are inhibitors of gram-positive organisms. ISO 16654 recommends preparing the initial suspension and adding a test portion to the 41,5 ºC pre-warmed broth to obtain a ratio of test portion to mTSB + sample of 1/10 (mass to volume, or volume to volume). Incubate for 6 hours then a further 12 hours to 18 hours at 41,5 ºC.

Thành phần phù hợp với yêu cầu của phương pháp phân tích E.coli O157 hoặc theo ISO 16654, cụ thể thành phần trong mỗi lít môi trường pha chế như sau:

• Sodium chloride: 8g
• Potassium chloride: 0,2g
• Disodium hydrogen phosphate (anhydrous) (hoặc Disodium phosphate): 1,44g
• Potassium dihydrogen phosphate (anhydrous) (hoặc Potassium phosphate): 0,24g
• Polyoxyethylene sorbitan monolaurate (tween 20 syrup) (hoặc Polysorbate): 0,2ml

– Giá trị pH:  7.2 + 0.2 ở 25⁰C.

• Casein peptone: 7,5g
• Meat peptone: 2,5g
• Sodium chloride: 5g
• MUG (4-methylumbelliferyl –β-D-glucuronide): 0,02g
• Lactose: 1g
• Phenol red: 0,025g
• L-Tryptophan: 0,5g
• Agar: 13-14g

• Thông số hiệu suất: Vi khuẩn coli O157:H7 phát triển tốt, âm tính MUG (không phát huỳnh quang dưới đèn UV)

Composition

Per vial sufficient for 500 ml medium
Potassium tellurite 1.250mg
Cefixime 0.025mg

Directions
Rehydrate the contents of 1 vial aseptically with 5 ml of sterile distilled water. Mix gently to dissolve the contents completely. Aseptically add the contents to 495 ml of sterile, molten, cooled (45-50ºC) MacConkey Sorbitol Agar Base . Mix well and pour into sterile petri plates

Principles and uses Casein Peptone is a pancreatic digest of casein. Pancreatic digestion produces a balanced mixture of amino acids, including essential amino acids, in optimal ration and low molecular peptides. In many cases, this makes for a more nutritious hydrolysate, especially for those organisms that prefer peptides to amino acids. It can be used in the production of toxins, vaccines, enzymes, in fermentation applications and microbiological culture media, especially in blood-containing media.

Principles and uses Bacteriological agar is a gelling agent used in the preparation of culture media and in other bacteriological applications. Its main advantage is the absence of inhibitors which could hinder optimal development of microorganisms. In addition, bacterio-logical agar also possesses other attributes such as transparency, high hysteresis and very reliable reproducibility. Bacteriological agar European Type has higher gel strength and is used in concentrations from 1,0% to 2,0%. Each batch produced by us is thoroughly tested for biological performance against a battery of known bacterial cultures in order to ensure proper growth characteristics and absence of inhibitors. Also, other tests are carried out to be certain that each batch meets established physical and chemical specifications.

This culture medium contains lactose, whose degradation to acid is indicated by the pH indicator phenol red, which changes its colour to yellow. The indicator exhibits a deep red colour in the alkaline range. The growth of the accompanying Gram-positive microbial flora, Salmonella typhi and Shigella is largely inhibited by brilliant green. The growth of Salmonella is, however, improved by the richer nutrient base. Increased growth of accompanying microorganisms is considerably prevented by raising the concentration of brilliant green. Salmonellae are not able to ferment either lactose or sucrose. Thus in contrast to BPL agar, the sucrose contained in this medium allows identification of accompanying, weakly lactose-positive or lactose-negative, but sucrose-positive microorganisms.

Principles and uses Irgasan Ticarcillin and Potassium Chlorate Broth (ITC) is recommended by ISO 10273 as a selective enrichment broth for the detection of the human pathogenic strain of Yersinia enterocolitica in food and water samples. Enzymatic casein digest provides nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group essential for bacterial growth. Magnesium chloride and malachite green, make the broth highly selective. Irgasan inhibits Gram-positive bacteria, Ticarcillin has bactericide on Gram-negative and Gram-positive bacteria and potassium chlorate has a disinfecting property.

Principles and uses
Sorbitol Peptone Broth And Bile Salts (PSB) is a medium recommended by ISO 10273 for the selective enrichment of Yersinia enterocolitica in food samples. Outbreaks of gastroenteritis associated with Yersinia enterocolitica are increasing. Contaminated food products such as pork, beef, and raw and processed milk have been identified as sources of infection.
Enzymatic digest of casein provides nitrogen, vitamins, minerals and amino acids essential for growth. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Potassium phosphates act as a buffer system. Sorbitol is the fermentable carbohydrate providing carbon and energy.

Preparation
Suspend 31 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Dispense into appropriate containers and sterilize in autoclave at 121°C for 15 minutes.

Yersinia Selective supplement is based on the formulation of Schiemann and is added to Yersinia medium base (CIN) in order to obtain a final selective medium for the isolation and enumeration of Yersinia enterocolitica from clinical specimens and food. Yersinia enterocolitica is becoming increasingly recognised as a cause of diarrhoeal disease of man and also polyarthritis, mesenteric adenitis and septicaemia.

Principles and uses
Yersinia Select Agar Base (ISO 10273) is a selective and differential medium when used with supplements. The formula is based on the CIN Agar described by Schiemann, and is recommended by ISO 10273 for the isolation and detection of presumptive pathogenic Yersinia enterocolitica from a variety of clinical and food samples.
Antibiotics are added as a supplement in order to inhibit the accompanying flora. The growth of Yersinia is promoted by pyruvate as well as by the nutrients content in the base. Yersinia degrades the mannitol of the medium to an acid form; the colonies are turning to red color due to the neutral red indicator. Mannitol fermentation in the presence of neutral red produces a characteristic “bull’s-eye” colony, colorless with a red center.
Mannitol is the fermentable carbohydrate, source of carbon and energy. Enzymatic digest of gelatin and the enzymatic digest of casein and animal tissues provide nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group.
Sodium pyruvate is added as a source of energy and as a protective substance in order to overcome oxygen toxicity biologically produced by the organisms. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Magnesium sulphate is an ion required in a large variation of enzymatic reactions, including DNA replication. Neutral red is the pH indicator. Selective inhibition of Gram-negative and Gram-positive organisms is obtained through crystal violet, sodium desoxycholate and Irgasan (triclosan). Cefsulodin and novobiocin improve the inhibition of normal enteric organisms.

Preparation
Suspend 28,5 grams of the medium in 500 ml of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Sterilize in autoclave at 121 ºC for 15 minutes. Cool to 45 ºC and aseptically add one vial of Yersinia Selective Supplement Homogenize gently and dispense into Petri dishes.

Principles and uses A1 Medium, also known as A1 Broth, is used for the detection of fecal coliforms in water samples. The enumeration of coliforms, specifically Escherichia coli, has been used to determine water purity by the most-probable-number method. This medium was created to hasten the recovery time of E. coli and to reduce the number of false positive cultures. A-1 Medium can be used in a single-step procedure, also in foods, not requiring a previous enrichment step. Tryptone provides nitrogen, vitamins, minerals and aminoacids. Lactose is the carbon source and in combinationwith salicin, provides energy for organism growth. Ecosurf is a surfactant and sodium chloride supplies essential electrolytes for transport and osmotic balance. Gas production is a positive reaction indicating the presence of Coliforms. Gas may be produced inside the Durham tubes or may appear as dissolved gas that forms gas bubbles when slightly agitated.

The use of animal tissue for culturing anaerobic organisms was first employed by Theobald Smith in 1890. Von Hibler later used brain tissue for cultivating and classifying anaerobic bacilli. Robertson replaced brain tissue with beef heart and used this medium to differentiate putrefactive and saccharolytic species. The formulation presently used is a modified version of Robertson’s formulation. This medium is also referred to as Chopped Meat Medium.  Nutritional requirements needed by most bacteria are provided by beef heart, peptone and dextrose. Dextrose, yeast extract, hemin and vitamin K are added to enhance the growth of anaerobic microorganisms. Amino acids and other nutrients are supplied by the muscle protein in the heart tissue granules. Reducing substances, which permit the growth of strict anaerobes, are supplied by the muscle tissue and the iron filings. It is thought that the meat particles act as a reducing and detoxifying substance, thereby disabling harmful by products that may be produced by the replicating organism. Because reducing substances are more available in denatured protein, the meat particles are cooked before use in the medium. Growth of spore-forming and non-spore-forming obligate anaerobes is supported by this medium. Cooked Meat Medium is also useful as an enrichment broth for cultivating organisms from a very small inoculum. Additionally, researchers have found that Cooked Meat Medium preserves viability of organisms over a long period of time and is useful in maintaining anaerobic stock organisms. The Food and Drug Administration recommends its use in the enumeration and identification of Clostridium perfringens from food.

Principles and uses TGEA Medium (Tryptone Glucose Yeast Extract Agar) is a medium used for the total count of aerobic mesophilic bacteria in water and dairy products. Casein Peptone and Beed Extract provide nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is source of vitamins, particularly the B-group. Dextrose is the fermentable carbohydrate providing carbon and energy. Bacteriological agar is the solidifying agent

A sterile selective supplement used for isolation and presumptive identification of Clostridium perfringens, according to ISO 7937 and ISO 14189, and other regulations.

Compositon (g/vial) D-Cycloserine………………………………………………. 0.200 Reconstitute the original freeze-dried vial by adding Sterile Distilled Water…………………………………….6 ml

Note: each vial is sufficient to supplement 500 ml of medium. TSC Agar Base.

D-cycloserine selective supplement is added to TSC Agar in order to obtain a final selective medium which has the advantage to simplify the counting of plates with high numbers of colonies because smaller colonies of C.perfringrens are formed. Sodium metabisulphite and ferric ammonium citrate are used as an indicator of sulphite reduction made by Clostridium perfringens spp. that produce black colonies in TSC agar.

Principles and uses
Hektoen Enteric Agar is a differential and selective medium used for isolating and differentiating enteric pathogens such as Salmonella and Shigella, both of which cause a variety of serious human gastrointestinal diseases; and other Gram-negative Enterobacteriaceae.
It is used particularly in foods where multi-steps are followed to isolate the pathogens of gastroenteritis. The nutrients for growth are provided by the Meat Peptone and Yeast extract. The increased content of the Peptone and the three fermentable carbohydrates (Lactose, Sucrose, Salicin) as sources of carbon and energy reduce the inhibitory action of the Bile salts on Salmonella and Shigella spp. The lactose concentration in this medium is higher than in many other media used for enterics since this helps the visualization of enteric pathogens and minimizes the problem of delayed lactose fermentation. Bromothymol blue and Acid fuchsin are pH indicators. Sodium thiosulfate provides Sulphur, and Ferric ammonium citrate is the indicator for
H2S production. H2S positive colonies are black-centered. Sodium chloride maintains the osmotic balance.
The norma ISO 21567 recommends the Hektoen Agar as a selective solid media for the enumeration of Shigella spp. Although suppressed, partially inhibited E. coli and other organisms which use lactose, sucrose, and/or salicin with the production of acid, give colonies whose tones vary from yellow to orange to salmon. The Salmonella and Shigella are green or green-blue. Proteus is not inhibited but produces a green-yellow colony when it grows. The colonies of Proteus and Salmonella may present a black center and clear edges if they form iron sulfide as a result of H2S production.

Preparation
Suspend 75,6 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. AVOID OVERHEATING. DO NOT AUTOCLAVE. Cool to 47 ºC and pour into Petri dishes.