Part of Thermo Fisher Scientific
Organisms in the Clinical sector this product works with:
LEGIONELLA CYE AGAR BASE
Code: CM0655
Charcoal Yeast Extract Agar for the isolation of Legionellaceae when used with Legionella BCYE Growth Supplement SR0110 (Edelstein BYCE Agar)
Typical Formula* | gm/litre |
Activated charcoal | 2.0 |
Yeast extract | 10.0 |
Agar | 13.0 |
LEGIONELLA BCYE GROWTH SUPPLEMENT
Code: SR0110
Vial contents | SR0110A | SR0110C | Supplement per litre |
Buffer/Potassium hydroxide | 1.0g | 5.0g | 10g |
Ferric pyrophosphate | 0.025g | 0.125g | 0.25g |
L-cysteine HCl | 0.04g | 0.2g | 0.4g |
a -Ketoglutarate | 0.1g | 0.5g | 1.0g |
Directions to prepare BCYE Agar
Suspend 2.5g of Legionella CYE Agar Base per 90ml of distilled water and bring gently to the boil to dissolve completely. Sterilise by autoclaving at 121°C for 15 minutes. Reconstitute one vial SR0110A per 100ml medium or one vial SR0110C per 500ml medium, as directed. Allow medium to cool to 50°C and aseptically add the vial contents. Mix gently and pour into sterile Petri dishes. The final pH of the medium should be 6.9 ± 0.2.
Description
The discovery of the causative organism of Legionnaires’ disease has been reviewed by Fallon1. Since that review further progress has been made in culturing the organism from clinical specimens and also in the enumeration of Legionella species from environmental samples. Feeley et al.2 described a modification of F-G Agar3 in which acid hydrolysed casein was replaced by yeast extract as the source of protein and starch was replaced by activated charcoal (Norit A) at a final concentration of 0.2% (w/v). This medium, which they named CYE Agar2 has been further supplemented with ACES Buffer and a-ketoglutarate and is described in the literature as BCYE-a Medium4. BCYE-a Medium has been shown to yield optimal recovery of Legionellaceae in a shorter incubation period from environmental samples and clinical specimens5.
Oxoid BCYE Medium is based on the formulation of Edelstein4 and is prepared from Legionella CYE Agar Base (CM0655) and Legionella BCYE Growth Supplement (SR0110). The sterile lyophilised supplement contains ACES Buffer/potassium hydroxide, a-ketoglutarate, ferric pyrophosphate and L-cysteine HCl. When added to CYE Agar Base it stabilises the pH of the medium at 6.9 ± 0.2 and provides essential growth factors.
This medium can be further supplemented with one of the following:
Additionally, a medium omitting L-cysteine may be prepared from Legionella CYE Agar Base (CM0655) and BYCE Growth Supplement (SR0175).
Legionellaceae have an absolute nutritional requirement for L-cysteine. Presumptive Legionella spp. colonies can be subcultured onto both BCYE Medium with L-cysteine (CM0655) and (SR0110), and BCYE Medium without L-cysteine (CM0655) and (SR0175).
All plates are incubated at 35°C. Colonies which have grown on BCYE Medium with L-cysteine, but not on BCYE Medium without L-cysteine, can be regarded as presumptive Legionella spp.
Storage conditions and Shelf life
Store the dehydrated medium below 30°C and use before the expiry date on the label.
Store the prepared plates at 2-8°C away from light.
Appearance
Dehydrated medium: Black, free-flowing powder
Prepared medium: Black gel
Quality control
Positive controls: | Expected results |
Legionella pneumophila ATCC® 33152 * | Good growth; grey/white coloured colonies |
Legionella pneumophila NCTC 12821 | Good growth; grey/white coloured colonies |
Negative control: | |
Uninoculated medium | No change |
Selective media | |
Positive controls: | |
Legionella pneumophila ATCC® 33152 * | Good growth; grey/white-blueish coloured colonies |
Legionella pneumophila NCTC 12821 | Good growth; grey/white-blueish coloured colonies |
Negative control: | |
Staphylococcus epidermidis ATCC® 12228 * | Inhibited |
References
1. Fallon J. Oxoid Limited. Culture September 1979, P. 3-4.
2. Feeley J.C., Gibson R.J., Gorman G.W., Langford N.C., Rasheed J.W., Mackel D.C. and Baine W.B. (1979) J. Clin. Micro. 10. 437-441.
3. Feeley J.C. Gorman G.W., Weaver R.E., Mackel D.C. and Smith H.W. (1978) J. Clin. Micro. 8. 320-325.
4. Edelstein P.H. (1981) J. Clin. Micro. 14. 298-303.
5. PHLS Communicable Diseases Report (1983) CDR 83/49.