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OXOID NOVEL ENRICHMENT (ONE) BROTH-LISTERIA

ONE BROTH LISTERIA BASE

Code: CM1066

A selective enrichment broth for Listeria species from food samples in 24 hours

* Adjusted as required to meet performance standards

ONE BROTH-LISTERIA SELECTIVE SUPPLEMENT

The formulation of ONE Broth-Listeria Selective Supplement is not published.

Code: SR0234

ONE Broth-Listeria is the selective enrichment broth used in the Oxoid Listeria Precis™ rapid culture method. For information simply download the ONE Broth-Listeria data sheet (273KB) or the Listeria Precis data sheet (680KB) in PDF format.

Directions
Suspend 22g of ONE Broth-Listeria Base in 500ml (44g/l) of distilled water. Mix well and sterilize by autoclaving at 121°C for 15 minutes. Cool the medium to below 50°C and aseptically add the contents of one vial of ONE Broth-Listeria Selective Supplement (SR0234) reconstituted as directed.

Description
A novel broth developed by Oxoid for the selective enrichment and isolation of Listeria species from food samples. Recovery of Listeria spp. after 24 hours using ONE Broth-Listeria has been shown to be comparable and in some cases better than using the ISO 11290-1¹ combined Fraser and Half Fraser broth enrichment procedure².

This novel enrichment broth incorporates a carefully balanced mixture of peptones, carbohydrates and salts to give optimal resuscitation, recovery and growth of even low numbers of Listeria spp. from food samples after 24 hours. Convenient freeze-dried vials provide easy addition of selective agents to the broth base allowing recovery of Listeria spp. while inhibiting a wide range of competing flora.

Internal trials and an evaluation carried out on behalf of Oxoid at Leatherhead Food International show that at 24 hours ONE Broth-Listeria is capable of the improved recovery of Listeria when compared to Half Fraser Broth² alone or Half Fraser followed by full Fraser Broth. In addition, the number of Listeria cells detected after broth enrichment for 24 hours was found to be higher with ONE Broth-Listeria than with Half Fraser Broth.

ONE Broth-Listeria offers the benefit of requiring a single enrichment medium at one temperature, with no need to sub-culture into a secondary enrichment broth. Listeria recovery levels at 24 hours are at least equivalent to the ISO enrichment method for and in some cases are improved^2,3.

Technique

1. Add 25g of food sample to 225ml of ONE Broth-Listeria and stomach for a minimum of 30 seconds to mix the sample.
2. Incubate the broth without agitation at 30°C for 24 ± 2 hours.
3. Gently agitate the bag then, using a microbiological loop, remove 10µl and inoculate onto a suitable agar medium e.g. Brilliance Listeria Agar (CM1080+SR0227+SR0228) and incubate appropriately (37°C for 24-48 hours).
4. Confirm presumptive colonies on the agar plates as Listeria monocytogenes or Listeria spp. by appropriate methods e.g. Gram-stain, catalase, oxidase, Oxoid Listeria Latex Test Kit DR1126, Oxoid O.B.I.S. mono ID0600, Microbact Listeria 12L MB1128.

Storage conditions and Shelf life
ONE Broth-Listeria Base must be stored tightly capped in the original container at 10-30°C. ONE Broth-Listeria Selective Supplement should be stored in the dark at 2-8°C.
Store the prepared medium for up to 4 weeks at 2-8°C.

Appearance
Dehydrated medium: straw coloured, free-flowing powder
Selective supplement: orange/yellow, freeze-dried pellet
Prepared medium: dark straw coloured, clear liquid

Quality control

* This organism is available as a Culti-Loop®

Precautions
ONE Broth-Listeria Base and ONE Broth Selective Supplement are for Laboratory Use Only.
ONE Broth-Listeria Base is designated as "Irritant" and ONE Broth-Listeria Selective Supplement is designated as "Harmful". For a full Material Safety Data Sheet (MSDS).
Do not use ONE Broth-Listeria Base or ONE Broth-Listeria Selective Supplement beyond the stated expiry dates, or if the products show any sign of deterioration.

References
1. ISO 11290-1 (Microbiology of food and animal feeding stuffs – Horizontal method for the enumeration of Listeria monocytogenes – part 1).
2. Oxoid Poster - Folio No. 1033, July 2004.
3. Data on file at Oxoid.