D/E Neutralising Broth (Dey & Engley)

Tietoa tuotteesta

Description:

D/E Neutralising Broth is used to neutralise and determine the bacteriocidal activity of antiseptics and disinfectants. Developed by Dey and
Engley, D/E Neutralising Broth neutralises a broad spectrum of antimicrobial chemicals, producing better results than those obtained using
alternatives such as Letheen Broth, Thioglycollate Medium and Neutralising Buffer. Complete neutralisation is required to prevent false
results arising from disinfectant carryover. When used with D/E Neutralising Broth Base the action of the antimicrobial agent can be
assessed, i.e. whether it is bacteriostatic or has bactericidal properties. The procedure is based upon D/E Neutralising Broth Base being
deficient of all neutralising agents, therefore the potency of the disinfectant is not diminished after addition to the medium. Whereas, when
disinfectant is added to the D/E Neutralising Broth, its activity is neutralised allowing for the detection of any bacteria presence. D/E
Neutralising Broth contains thioglycollate to neutralise mercurial compounds, sodium thiosulphate to neutralise iodine and chlorine and
sodium bisulphite to neutralise formaldehyde and gluteraldehyde. Lecithin is included to neutralise quaternary ammonium compounds and
Tween® 80 neutralises phenols, hexachlorophene, formalin, and combined with lecithin, ethanol. Bromocresol purple allows detection of
growth via a colour change from purple to yellow when organisms ferment the glucose contained in the medium.

Formula g/litre
Glucose 10.0
Lecithin 7.0
Sodium thiosulphate 6.0
Tween®80 5.0
Tryptone 5.0
Sodium bisulphite 2.5
Yeast extract 2.5
Sodium thioglycollate 1.0
Bromocresol purple 0.02

Method for reconstitution
Weigh 39.0 grams of powder and disperse in 1 litre of deionised water. Allow the mixture to soak for 10 minutes, swirl to mix and dispense
into final containers. Sterilise by autoclaving at 121°C for 15 minutes.

Appearance: Purple opaque liquid.

pH: 7.6 ± 0.2

Minimum Q.C. organisms:
Bacillus subtilis NCIMB 8054
Escherichia coli NCIMB 12210
Pseudomonas aeruginosa NCIMB 12469
Salmonella typhimurium NCIMB 13284
Staphylococcus aureus NCIMB 12702

Storage of Powder: Store at 2-8°C in the dark. The formulation is very hygroscopic therefore keep the container tightly closed after use.
Storage of Prepared Medium: Capped containers – up to 3 months at 15-20°C in the dark.

Inoculation: Consult appropriate references as this product is used in several procedures.
Incubation: 37°C aerobically for 24-48 hours.

Interpretation: Examine all tubes for increased turbidity, formation of a pellicle or a colour change from purple to yellow, indicating
bacterial growth.

References
Roberts D., Hooper, W. and Greenwood, M., (1995). Methods for the examination of food for micro-organisms of public health
significance, 2nd edition, section 5.10, Practical Food Microbiology. Butler & Tanner. ISBN 0 901144 36 3.
Engley Jr., F.B. and Dey, B.P. (1970). A universal neutralising medium for antimicrobial chemicals. Presented at the Chemical Specialities
Manufacturing Association (CSMA) Proceedings, 56th Mid Year Meeting.
Dey, B.P. and Engley Jr., F.B. (1995). Comparison of Dey and Engley (D/E) Neutralising medium to Lethhen medium and Standards
Methods Medium for recovery of Staphylococcus aureus from sanitised surfaces. J. Ind. Microbiol. 14:21-25.
Curry, A.S., Graf, J.G. and McEwen Jr., G.N. (ed.) (1993) CFTA Microbiology Guidelines. The Cosmetic, Toiletry and Fragrance
Association, Washington, D.C.