Meios de Cultura Prontos a Usar
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Meios de Cultura prontos a usar
CN Agar For Pseudomonas
Enumeration Of Pseudomonas Aeruginosa In Water
CN Agar for Pseudomonas is a selective medium for the isolation and enumeration of Pseudomonas aeruginosa in bottled water, swimming pools and water destined for human consumption.
The formula of the base medium is a modification of King A medium, in which magnesium chloride and potassium sulfate favor pyocyanin production. In 1951, Lowbury recommended the use of cetrimide in a selective medium for the isolation of Pseudomonas. Following the improvement in the purity of the inhibiting agent, its concentration was reduced by Lowbury and Collns in 1955. Goto and Enomoto demonstrated that the addition of nalidixic acid, with a decrease in the concentration of cetrimide, allowed for a better recovery of Pseudomonas aeruginosa with a correlative increase in pigment production, while contaminating flora (Proteus, Klebsiella, Providencia) were strongly inhibited. 3 PRINCIPLES Pancreatic digest of gelatin and acid hydrolyzed casein are the nutrient substrates required for the rapid multiplication of Pseudomonas. The production of pyocyanin (a blue, non-fluorescent pigment, soluble in water and in chloroform) is stimulated by magnesium chloride and potassium sulfate. Contaminating yeasts are inhibited by cetrimide. Nalidixic acid blocks the DNA replication of bacteria sensitive to this antibacterial agent. Colonies demonstrating a blue-green pigmentation are considered as Pseudomonas aeruginosa. The other types of colonies are presumptive Pseudomonas aeruginosa and must be confirmed.
Compass® Salmonella Agar
Detection Of Salmonella
COMPASS® Salmonella Agar is a selective media allowing the isolation and differentiation of bacteria belonging to the genus Salmonella.
It can be used as the second media in all normalized and validated methods for the detection of Salmonella.
COMPASS® Salmonella Agar is also used in the context of the rapid alternative method for the detection of Salmonella (SESAME Salmonella TEST®).
At the beginning of the 1990’s, several authors demonstrated that the majority of Salmonella strains of all species and serotypes were capable of cleaving esters of 7 to 10 carbon atom fatty acids. The esterase, particularly active on caprylate derivatives, was detected through the use of synthetic fluorogenic and chromogenic substrates. However, their hydrophobic nature prevented incorporation into agar media. As a result, droplet testing for fluorescence was applied to colonies on isolation media : Hektoen, SS, XLD, etc. In 1997, a new culture medium formulation was devised to incorporate hydrophobic chromogenic substrates into aqueous media in such a way as to obtain homogeneous and stable agar media, therefore enabling direct detection of Salmonella esterase on culture media. Other bacteria lacking esterase and/or possessing a β-glucosidase enzyme were detected with a second chromogenic substrate are thus distinguishable from Salmonella. 3 PRINCIPLES COMPASS® Salmonella Agar combines two chromogenic substrates in order to detect two enzyme activities : – 5-bromo-6-chloro-3-indolyl-caprylate (Magenta-caprylate) allows the revelation of the esteraise enzyme. Degraded by Salmonella, this enzyme leads to the formation of a red-violet (magenta) precipitate within the colony. – 5-bromo-4-chloro-3-indolyl-β-D-glucopyranoside (X-glucoside) is also used for which the cleavage product is a blue precipitate. Simultaneous detection of both activities allows for a coloration of Salmonella in distinct contrast to that of other bacteria. Studies have demonstrated the enhanced specificity for Salmonella detection using this method, including atypical serotypes which can cause confusion on other media. The detection of Salmonella Typhi and Paratyphi, lactose positive Salmonella (S. Seftenberg and sub-species arizonae and diarizonae), sucrose positive and nonmotile serotypes (S. Pullorum and Gallinarum) is assured with this medium. Selective agents inhibit Gram-positive and several Gram-negative species. The nutrient base favors the recovery and growth of Salmonella