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Cystine tryptic agar (CTA) which is also referred to as cystine trypticase agar was created by Vera as an semi-solid growth medium to identify and maintain the health of microorganisms for long time period of time when stored at suitable temperatures. It’s used for determination of the motility of bacteria and, when combined with carbohydrate, is involved in the fermentation process and the differentiation of microorganisms that are fastidious, such as Neisseria and streptococci, as well as pneumococci and non-spore-forming anaerobes.
Raymond Sabouraud created Sabouraud Dextrose Aga or SDA in 1892. Sabouraud Dextrose Aggar is useful in the cultivation of fungi (yeasts and moulds), especially for skin infections.
To ensure that clinical specimens are properly cultured, two types of media are required. The non-selective medium (e.g. Brain Heart Infusion Agar) should be used. Other media should be specific and tailored to isolate pathogenic fungi.
A selective medium called phenylethyl alcohol (PEA), is used to cultivate Gram positive organisms, especially cocci, in a sample containing pathogens. Phenylethyl alcohol is the active ingredient that inhibits or significantly reduces growth of Gram-negative organisms.
Anaerobic Culture Media used in anaerobic bacteriology may be prepared in a fresh manner or bought from commercial vendors.
Media for anaerobic fermentation that is created in the laboratory should be used within two weeks after the time of preparation, as prolonged storage can degrade the quality of the medium due to peroxide accumulation and dehydration.
Lowenstein Jensen Medium (LJ Medium) is a highly selective medium.
Solid media that are used to isolate as well as cultivation of Mycobacteria can be egg-based or Agar-based.
Potato Dextrose Agar (PDA) is commonly abbreviated as PDA.
Potato Dextrose Agar has been suggested by APHA and F.D.A.for the count of moulds and yeasts during the testing of food items and dairy products.
Xylose Lysine Deoxycholate agar (XLD) is a selective medium that allows for the isolation and growth of Salmonella and Shigella species using clinical samples or food. Taylor developed XLD Agar to aid in the differentiation, isolation and identification of enteric disease agents and support the growth more specialized enteric organisms. XLD Agar is a well-proven medium that allows the growth of Shigella species. It is also an excellent medium to isolate Salmonella species. It has a pH value of 7.4, giving it a bright pink to red color due to the indicator phenol.
Mannitol Salt Agar (MSA) is utilized as a differential and selective medium to isolate and detect Staphylococcus aureus in clinical and non-clinical samples. It is recommended for identification and enumeration of coagulase positive Staphylococci that are present in milk, food as well as other specimens. MSA also promotes an increase in the number of particular group of specific bacteria, while limiting the growth of other bacteria.
