XLD agar

Jump to: navigation, search

WikiDoc Resources for XLD agar

Articles

Most recent articles on XLD agar

Most cited articles on XLD agar

Review articles on XLD agar

Articles on XLD agar in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on XLD agar

Images of XLD agar

Photos of XLD agar

Podcasts & MP3s on XLD agar

Videos on XLD agar

Evidence Based Medicine

Cochrane Collaboration on XLD agar

Bandolier on XLD agar

TRIP on XLD agar

Clinical Trials

Ongoing Trials on XLD agar at Clinical Trials.gov

Trial results on XLD agar

Clinical Trials on XLD agar at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on XLD agar

NICE Guidance on XLD agar

NHS PRODIGY Guidance

FDA on XLD agar

CDC on XLD agar

Books

Books on XLD agar

News

XLD agar in the news

Be alerted to news on XLD agar

News trends on XLD agar

Commentary

Blogs on XLD agar

Definitions

Definitions of XLD agar

Patient Resources / Community

Patient resources on XLD agar

Discussion groups on XLD agar

Patient Handouts on XLD agar

Directions to Hospitals Treating XLD agar

Risk calculators and risk factors for XLD agar

Healthcare Provider Resources

Symptoms of XLD agar

Causes & Risk Factors for XLD agar

Diagnostic studies for XLD agar

Treatment of XLD agar

Continuing Medical Education (CME)

CME Programs on XLD agar

International

XLD agar en Espanol

XLD agar en Francais

Business

XLD agar in the Marketplace

Patents on XLD agar

Experimental / Informatics

List of terms related to XLD agar


Xylose lysine deoxycholate agar (XLD agar) is a selective growth medium used in the isolation of Salmonella and Shigella species from clinical samples and from food. It has a pH of approximately 7.4, leaving it with a bright pink or red appearance due to the indicator phenol red. Sugar fermentation lowers the pH and the phenol red indicator registers this by changing to yellow. Most gut bacteria, including Salmonella, can ferment the sugar xylose to produce acid; Shigella colonies cannot do this and therefore remain red. After exhausting the xylose supply Salmonella colonies will decarboxylate lysine, increasing the pH once again to alkaline and mimicking the red Shigella colonies. Salmonellae metabolise thiosulfate to produce hydrogen sulfide, which leads to the formation of colonies with black centers and allows them to be differentiated from the similarly coloured Shigella colonies.

  • Salmonella species: red colonies, some with black centers.
  • Shigella species: red colonies.
  • Coliforms: yellow to orange colonies.
  • Pseudomonas aeruginosa: pink, flat, rough colonies.

XLD agar contains:

Yeast extract 3g/l
L-Lysine 5g/l
Xylose 3.75g/l
Lactose 7.5g/l
Sucrose 7.5g/l
Sodium deoxycholate 1g/l
Sodium chloride 5g/l
Sodium thiosulfate 6.8g/l
Ferric ammonium citrate 0.8mg/l
Phenol red 0.08g/l
Agar 12.5g/l

See Also




Linked-in.jpg