Should the SOLO+ media be pre-warmed?

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.