Amies Transport Medium, which contains charcoal to increase the viability and longevity of pathogenic organisms, is an improved transport medium. It is semisolid media that can be used in qualitative procedures to transport clinical swab specimens from the hospital to the laboratory. This modified Stuart’s Transport Medium is made by adding charcoal to the medium and replacing the glycerophosphate. This modified medium produced a higher percentage positive results than Stuart’s transport medium.
Thioglycolate broth, an enrichment broth that is multipurpose and can be used to determine the oxygen needs of microorganisms, is called a differential medium. It is used most often in diagnostic bacteriology as an enrichment broth. This broth is supportive of the growth and development of microorganisms fastidious, anaerophilic, microaerophilic and aerobes.
In 1978, Feeley et al developed a medium for isolating Legionella species. They later modified it by replacing casein hydrolysate with beef extract and starch with activated carbon and naming it Charcoal Yeast extract (CYE) Agar. A further modification was made by Pasculle et al in 1980 by the addition of ACES (N-2-acetamido-2-aminoethane sulfonic acid) buffer in order to maintain the proper pH for optimal growth designated as BCYE for Buffered Charcoal Yeast Extract. Edelstein et al modified the medium in 1981 by adding potassium salt to alpha-ketoglutaric acids, which increased the medium’s sensitivity. It is used in primary isolation and cultivation of Legionella species. It is recommended to be used in the cultivation and primary isolation of Legionella spp.
Cetrimide, a quaternary salt of ammonium, acts as a detergent that lowers the surface tension at the point-of-contact. It also has precipitant, complexing, and denaturing effects upon bacterial membrane proteins. It has inhibitory properties on many microorganisms, including Pseudomonas species that are not Pseudomonas. Lowburry was the first to develop cetrimide agar. It is a modified version of Tech Agar (developed in King et al. For the selective inhibition other than Pseudomonas, aeruginosa, 0.1% cetrimide (cetyltrimethyl ammonium bromide), was added. Cetrimide agar can be used to presumptive identify and selectively isolate Pseudomonas.aeruginosa species from both clinical and nonclinical specimens.
Over the years, many media have been developed for mycobacteria cultivation. Early ones included egg-based formulations such as Lowenstein-Jensen Medium or Petragnani Medium. Later, Dubos, Middlebrook and Middlebrook created a variety of formulations that contained oleic and albumin as key components. These ingredients protect Mycobacterium against toxic agents and allow for the growth and development of tubercle bacteriailli. Cohn and Middlebrook improved the formulations of oleic acids-albumin agar to achieve a faster and more luxurious growth of Mycobacterium strains.
Endo created Endo Agar to distinguish gram-negative bacteria based on lactose fermentation and inhibit gram-positive bacteria. The latter were not inhibited by bile salts, as was traditional. Endo was able to inhibit gram-positive bacteria using sodium sulfite, basic fuchsin.
Salmonellae are the most complex taxonomically diverse group of bacteria in Enterobacteriaceae. Salmonella infections in humans are usually caused by the consumption of food, milk, and water contaminated with animal or human excreta. S. Typhi is only found in humans.
Egg Yolk Agar modified is based upon the original Egg Yolk Agar formula developed by McClung & Toabe to isolate and differentiate organisms based in Lecithinase, lipase production, and proteolytic activities.
As a primary plating medium, Brilliant Green Agar medium should be used to isolate Salmonella species. Kristensen and colleagues first described it as a selective isolation medium to Salmonella species. Kristensen et al. first described it as a selective isolation medium for Salmonella species. Kauffmann modified the formula to make it a highly selective plating media for the isolation and identification from salmonellae in feces, other pathological material, food and dairy products. Brilliant Green Agar should always be used in conjunction with other selective plating media like Deoxycholate Citrate Agar and Hektoen Enteric Agar. Salmonella Typhi is treated with Bismuth Sulphite.
Hektoen Enteric Agar, a selective and differential medium, is used to distinguish Salmonella and Shigella species from other Enterobacteriaceae. Sylvia King, William I. Metzger introduced the medium in 1968. They developed HE Agar medium during their time at the Hektoen Institute, Chicago, in order to improve the recovery of Salmonella and Shigella from clinical specimens.
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