DCLS Agar (Deoxycholate Citrate Lactose Sucrose Agar)

EMD Cat. No. 1.10270.0500
500 g


Selective agar for the isolation and differentiation of pathogenic Enterobacteriaceae and Vibrios (Vibrio comma and its biotype El Tor) from various materials.

According to the comprehensive studies of BURKHARDT et al. (1968) and BURKHARDT (1977), this culture medium has proved to be of value, when screening for Salmonella, Shigella and cholera vibrios. THAI and CHEN (1955) also reported that pathogenic Yersinia (Pasteurellae), e.g. Yers. pestis and Yers. pseudotuberculosis grow on this medium.






Mode of Action Preparation
Experimental Procedure and Evaluation Quality Control
Typical Composition (g/liter) Literature


Mode of Action
 The composition and mode of action of this culture medium largely corresponds with LEIFSON agar. The addition of sucrose allows the differentiation of lactose- and sucrose-negative Salmonella, Shigella and Arizona colonies from lactose-negative, sucrose-positive bacteria such as Proteus vulgaris, Serratia etc. When compared with LEIFSON agar, this medium has the advantage that, owing to its sucrose content, there is no danger of obtaining false-positive results when trying to detect pathogenic Enterobaceriaceae.


Typical Composition (g/liter)
 Peptone from meat 5.0; meat extract 5.0; lactose 10.0; sucrose 10.0; tri-sodium citrate-2-hydrate 6.0; sodium thiosulfate 4.0; sodium deoxycholate 3.0; ammonium iron(III)citrate 1.0; neutral red 0.02; agar-agar 13.0.

Preparation
 Suspend 57 g in 1 liter rapidly and completely, cool rapidly, pour plates so as to obtain thick layers.
  •   Do not autoclave.
     pH: 7.5 ± 0.2 at 25°C.
     The plates are clear and reddish-brown.
  •   Storage: up to 1 week at +2 to +8°C.

    Experimental Procedure and Evaluation
     Dry the surface of the poured plates and inoculate.
     Incubation: 24 hours at 35 °C aerobically.

    Quality control

    Test strains
    		 Growth
         		Colony color
         		Precipitate
    Enterobacter cloacae ATCC 13047
         		fair / good
         		red
         		+
    Escherichia coli ATCC 25922
         		none / poor
         		red
    Klebsiella pneumoniae ATCC 13883
         		fair / good
         		red
         		+
    Salmonella typhimurium ATCC 14028
         		good / very good
         		colorless
    Salmonella choleraesuis ATCC 13312
         		good / very good
         		colorless
    Salmonella enteritidis ATCC 13076
         		good / very good
         		colorless
    Shigella flexneri ATCC 12022
         		fair / good
         		colorless
    Proteus vulgaris ATCC 13315
         		fair / good
         		colorless
         		±
    Proteus mirabilis ATCC 14273
         		Fair / good
         		colorless
    Pseudomonas aeruginosa ATCC 27853
         		fair / good
         		colorless
    Staphylococcus aureus ATCC 25923
         		none

    Bacillus cereus ATCC 11778
         		none



    Literature

    BURKHARDT, F.: Zur Leistungsfähigkeit des durch Saccharose-Zuatz modifizierten Leifson-Nährbodens - Zbl. Bakt. Hyg., I. Orig., 239; 488-492 (1977).
     BURKHARDT, F., SUNTHORNSARATUL. A., EKACHAMPAKA, P., a. KREEPANICH, K.: Epidemiological studies on cholera vibrios and other enteropathogenes (Salmonella, Shigella) in two slum areas of Bangkok. - Bull. Dep. Med. Science, Bangkok, 10, 1-25 (1968).
     THAI, E., a. CHEN, T.H.: Two simple tests for the differentiation of plague and Pseudotuberculosis bacilli. - J. Bact., 69; 10³-104 (1955)


    © 2002 Merck KGaA, Darmstadt, Germany