Hoyle’s Agar

Hoyle’s Agar

SKU: KM0073 Category:

Hoyle’s agar is selective culture medium for the isolation and differentiation of Corynebacterium diphtheriae types. Hoyle’s agar allows for rapid growth of the organisms and normally 18 hours incubation should be sufficient for a diagnosis. As the medium is highly selective, inoculation should be by rubbing the swab (or other material) over the entire surface of the agar, there is no need to spread the inoculum with a loop indeed doing so can cause the organism to be missed especially when they are present only in small numbers. The Elek method can be used to determine the toxigenicity of any C. diptheriae strains.
The beef extract and peptone act as a source of nitrogen, carbon and vitamins. The sodium chloride maintains osmotic balance. This medium should be used in conjunction with two supplements: lysed horse blood at 50 ml/l and 10ml/l of potassium tellurite 3.5% solution (BM2230). Lysed horse blood provides added nutrients to the medium and potassium tellurite inhibits Gram-negative and several Gram-positive microorganisms.

Related Supplements :
BM2290 3.5% Potassium Tellurite Solution, Horse Blood Lysed

Additional Information

Shelf Life (days)

Storage Temp (°C)

Dehydrated Medium Appearance

Prepared Medium Appearance

Dehydrated Medium Colour

Prepared Medium Colour

Dehydrated PH

Prepared PH

Product Description

Organisms Ref. No Result
Corynebacterium diptheriae NCTC 10356 Growth, grey / black colonies
Staphylococcus aureus NCTC 12981 Inhibited



Beef extract 10.0
Peptone 10.0
Sodium chloride 5.0
Agar 12.0
Total 37.0
*Adjusted/supplemented as required to meet performance requirements


Suspend 37g of the medium in one litre of deionised / purified water. Allow the medium to soak whilst mixing for 10 minutes. Heat with frequent agitation and boil for one minute to completely dissolve the medium. Sterilise at 121°C for 15 minutes. Cool to 45-50°C, aseptically add 50 ml lysed horse blood and 10 ml/l potassium tellurite 3.5% solution (BM2230). Mix well and dispense into appropriate sterile containers.