-
Dey & Engley Broth has the ability to neutralise antimicrobial chemicals and is used for environmental sampling for the detection and enumeration of microorganisms present in cosmetic and/or environmental samples. In this formulation the broth has been modified by the addition of Tween 80 (Polysorbate 80), Lecithin, Sodium thioglycollate, Sodium thiosulphate and Sodium bisulphite. It is recommended for use in environmental testing, particularly in areas subjected to surface disinfection, and conforms to the requirements of the British Pharmacopeia for sterility testing of appropriate pharmaceutical products. The product also conforms to ISO 21149 to act as a diluent in the method for the enumeration of aerobic bacteria from cosmetic samples. Lecithin and Polysorbate 80 (Tween 80) inactivate surface disinfectants (Lecithin neutralises quaternary ammonium compounds and Tween 80 neutralises phenols, formalin, hexachlorophene and in combination with the Lecithin ethanol). Sodium thioglycollate neutralises mercurials, Sodium thiosulphate neutralises iodine and chlorine and Sodium bisulphite neutralises aldehydes. Bromocresol purple is incorporated into the medium to indicate glucose utilisation. -
A selective culture medium for the isolation and differentiation of Corynebacterium diphtheriae types, Hoyle’s medium 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.
