X.L.D. (XYLOSE LYSINE DEOXYCHOLATE) AGAR

Technical Data #1742a / 2013.06.11

XLD Agar is a moderately selective and differential solid medium for the isolation of gram-negative enteric pathogens from clinical and non-clinical specimens. Addition of xylose differentiate enteric pathogens from Shigella, the only enteric pathogens non-xylose fermenting. Deoxycholate inhibits gram-positive. Complex sodium thiosulfate-ferric ammonium citrate produces black-centered colonies when ferric ammonium citrate precipitates (H2S production).

 


 

FORMULA
in grams per liter purified filtered water

Yeast Extract

3,0

Lactose

7,5

Sucrose

7,5

Xylose

3,5

L-Lysine

9,0

Sodium Chloride

5,0

Ferric Ammonium Citrate

0,8

Sodium Thiosulfate

6,8

Sodium Deoxycholate

2,5

Phenol Red

0,08

Agar

13,5

pH 7.4 +/- 0,2 25 C

This approximate formula may be adjusted and/or enriched to obtain best results.


PRECAUTIONS
This medium is for IN VITRO diagnostic use only.


STORAGE
Store prepared media at 2-8 C protected from direct light and dehydrated powder, in a dry place, in tightly-sealed containers at 2-25 C.


SIGN OF DETERIORATION
Media should not be used if the expiry date has passed. Prepared media should not be used if there are signs of contamination or deterioration (shrinking, cracking, evaporation or discoloration). Do not use dehydrated media if it is caked.


DIRECTIONS
Suspend 55 g of dehydrated media in 1000 ml of purified filtered water. Heat with frequent agitation and boil for one minute. DO NOT STERILIZE. Cool to 45-50 C. Mix gently and dispense into sterile Petri dishes.


PROCEDURE
Prior to inoculate, the prepared media should be brought to room temperature.

  1. Directly, inoculate plate as soon as possible with specimen and streak for isolation. If inoculation will be delayed, an Enteric Pathogen Transport Medium as EPT-100 should be used.
  2. Incubate at 35 C for 24-48 hours.


QUALITY CONTROL

Results after 24 hrs at 35C

Organisms

ATCC

Growth

Colour

Salmonella typhimurium

14028

+

red w/ H2S

Shigella flexneri

12022

+

red

Escherichia coli

25922

- or partial

 
Streptococcus faecalis

29212

- or partial

 


LIMITATIONS OF METHOD
This medium is only a part of the identification. Other tests may be required.


REFERENCES

  1. Lennette, E.H., Ballows, A., Hausler, W.J.Jr., and Shadomy, H.J. Manual of Clinical Microbiology. 4th ed. 1985 Washington D.C.: American society for Microbiology.
  2. N.C.C.L.S. 1990 Quality Assurance for Commercially Prepared Microbiological Culture Media. Approved Standard. Vol.10. No.14. NCCLS Document M22-A.
  3. Mac Faddin, Jean F., 1985 Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria. Vol.1. Baltimore, MD.: Williams & Wilkins.
  4. Taylor, W.I. 1965 Isolation of shigellae. Xylose lysine agars; new media for isolation of enteric pathogens. Am. J. Clin. Pathol. 44:471-475.


CATALOGUE NUMBERS

Dehydrated media 500 g QB-39-5610
     
Prepared media    
Plates, 100x15 mm 10/pkg 1742
Mono-Plates, 100x15 mm 10/pkg 1742M
     
Enteric Pathogen Transport, Vial 100/cs EPT-100

 


 

 

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