Xylose Lysine Deoxycholate (XLD) Crack Plus Serial Key [Latest] 2022 Free Download
Xoxose Lysine Deoxycholate is a selective medium for the isolation of Salmonella and Shigella spp from clinical specimens and food specimens. Xylose Lysine Deoxycholate (XLD) Crack was originally formulated by Taylor to isolate and identify Shigella from stool samples. Pathogens are distinguished not only by non-pathogenic lactose fermenters, but also by many non-pathogenic ones that do not ferment lactose or sucrose. In addition, the medium has been formulated to increase the growth rate of more challenging pathogens, which often cannot be increased due to the inclusion of extremely toxic inhibitors in other formulations. Results from a series of clinical evaluations supported the claim regarding the relatively high efficacy of XLD Agar in the primary isolation of Shigella and Salmonella. XLD agar is included in the USP microbial limit test for the presence or absence of Salmonella and is recommended for testing food, dairy, and water.
It uses sodium deoxycholate as a selective agent and is, therefore, an inhibitor of gram-positive microorganisms. Xylose is incorporated into the environment as it is fermented by almost all enteric substances except Shigella, and this property allows differentiation of Shigella species. Lysine is included to distinguish the Salmonella group from non-pathogenic because without lysine, salmonella rapidly ferments xylose and is indistinguishable from non-pathogenic species. After Salmonella depletes the xylose source, the lysine is attacked by the enzyme lysine decarboxylase and returns to an alkaline pH that mimics the Shigella reaction.
To prevent similar reversal of lysine-positive coliforms, lactose and sucrose are added to produce excess acid. Decomposition of xylose, lactose and sucrose in acid causes the color of the phenol red indicator to change to yellow. Bacteria that decarboxylate lysine in cadavers can be recognized by the appearance of a red coloration around the colonies due to the increase in pH. These reactions can occur simultaneously or in tandem, causing the pH indicator to show different hues or change color from yellow to red with prolonged incubation.
To add formulation differentiation, an H2S indicator system consisting of sodium thiosulfate and ferric ammonium citrate is included to visualize the hydrogen sulfide produced, resulting in the formation of colonies with black centers. Non-pathogenic H2S producers do not decarboxylate lysine; therefore, the acid reaction they produce prevents darkening of colonies, which only occurs at neutral or alkaline pH.
Uses of XLD Agar
- XLD agar is a selective differential medium for the isolation of Gram-negative enterogram pathogens from stool specimens and other clinical materials.
It is especially suitable for the isolation of Shigella and Salmonella species.
- Microbiological testing of food, water and dairy products.
XLD Agar Preparation
- Suspend 55 grams of anhydrous medium in 1000 ml of distilled or distilled water.
Heat until medium simmer, stirring frequently.
- Note: NO AUTOCLAVE.
- Immediately transfer to a water bath at 50 °C.
- After cooling, pour into sterile Petri dishes.
- Note: It is recommended not to prepare large volumes that require prolonged heating and may cause precipitation.
- Characteristics of XLD Agar colony
- Shigella and Salmonella colonies on XLD agar
Typical colonial morphology on XLD Agar is as follows:
- Salmonella Typhi – Red colonies, black centers
- Salmonella choleraesuis – Red Colonies
- Shigella sonnei – Red Colonies
- Shigella flexneri – Red Colonies
- Escherichia coli – Large, flat, yellow colonies; some strains can be inhibited
- Proteus vulgaris – Colonii galben
- Enterobacter / Klebsiella – Mucoid, Yellow Colonies
- Pseudomonas aeruginosa – Pink, flat, coarse colonies
- Gram positive bacteria – do not reproduce
Xylose Lysine Deoxycholate (XLD) Crack Plus Serial Key [Latest] 2022 Download from the given link below: