Questions & Answers
It depends on what sample size you are working with.
For standard 25g samples there’s no need to pre-warm the supplemented media. Although it wouldn’t cause you a problem if you did.
For 100g, 375g and environmental sponges or swabs you do need to pre-warm your supplemented media to 37°C.
How long do I need to pre-warm for? That will very much depend on the volume of media that you are working with. Obviously a 5L bottle would take longer to reach 37°C than a 1L bottle. During internal validation procedures, each lab should determine the most appropriate way to heat the supplemented BPW depending on volumes and incubator capacity. The following can be used as a guide.
For media batch volumes greater than 1 litre, media can be placed in walk-in incubators for a minimum of 16 hours (i.e. overnight). If walk-in incubators aren’t available, existing fan circulated incubators can be used that are capable of heating batches greater than 1 litre for a minimum of 16 hours. This will ensure the media is adequately heated to achieve maximum recovery of Salmonella from the sample.
Solus One Salmonella Supplement, when added to BPW, inhibits the growth of competing flora. However unlike other supplement formulations, Salmonella are not suppressed by the supplement. This is a common problem of supplements containing brilliant green for example.
Therefore Salmonella will grow to levels that are easily detected by the immunoassay, when this supplement is used.
Solus One Salmonella Supplement is part of our dedicated media range. The media in our range has been shown over time to perform consistently and reliably with our pathogen ELISA tests.
Good, consistent quality is important for the sensitive detection of target organisms and also the control of false positive results due to overgrowth of any background flora.
Solus dedicated media is available for our entire pathogen testing range in a number of convenient formats.
Learn more about Solus dedicated media
- For Solus One Listeria you will require
- SOLO+ media
- For the Solus Salmonella ELISA protocol you will require
- Buffered Peptone Water according to ISO 6579
- Rappaport Vassiliadis Soya broth (Solus RVS is recommended)
- For the Solus Listeria ELISA protocol you will require
- Half-Fraser broth
- Fraser broth
- RELM selective broth is recommended for use with the Solus system
- For the Solus coli 0157 ELISA protocol you will require
- Modified Tryptone Soya Broth + novobiocin (20mg/L)
The quality of RVS is an important factor in any ELISA, a good consistent media should be used and prepared correctly to ensure optimum performance. We strongly recommend the use of Solus RVS as it has been validated for performance with the Solus kit and each batch is performance checked against the Solus Salmonella ELISA kit. Our studies have shown that some brands are not suitable for use with this assay. If you are not using Solus RVS, you should validate your media for use with Solus Salmonella.
No, RVS broth must be autoclaved at 115°C unlike most media which is sterilised at 121°C. If these temperatures are not adhered to then there will be adverse effects on the assay.
Media should be stored at 2-8°C and protected from light. On the day of testing, remove the media from the fridge and allow to come to room temperature before use.
To achieve the best results from Solus One Listeria, the preparation of the single enrichment media, SOLO+, must be carried out correctly. The media can be prepared in batches and stored at 2-8°C for up to 2 weeks. However, it must be warmed up to 30°C immediately prior to use in the enrichment of environmental swabs and sponges. During internal validation procedures, each lab should determine the most appropriate way to heat the SOLO+ depending on volumes and incubator capacity. The following can be used as a guide.
The kit instructions state that the SOLO+ media must be heated for 2 hours at 30°C. This refers to media batch volumes up to 1 litre, as internally validated, and can be achieved by placing the media in an incubator with fan circulation or a walk-in incubator.
For media batch volumes greater than 1 litre, media can be placed in walk-in incubators for a minimum of 16 hours (i.e. overnight). If walk-in incubators aren’t available, existing fan circulated incubators can be used that are capable of heating batches greater than 1 litre for a minimum of 16 hours. This will ensure the media is adequately heated to achieve maximum recovery of Listeria if present in swabs.
It should be noted that unopened, autoclaved media can be kept at 30°C for up to 72 hours with no detrimental effect on performance. This allows technicians to put SOLO+ media in to warm on a Friday evening for use on Monday morning should they wish.