It is unsuitable for the isolation of S typhi, but its specificity may offer advantages in terms of easier recognition of suspect colonies, with fewer false positive picks. Mannitol lysine crystal violet brilliant green agar (MLCB) is a highly selective medium for the isolation of salmonellae, which has been used principally in food and environmental microbiology. Xylose lysine desoxycholate (XLD) and desoxycholate citrate (DCA) agars are probably the two media most commonly used for this purpose in the UK. For routine diagnostic work, XLD is most effective.Ī wide variety of selective, direct plating media has been used in the isolation of Salmonella enterica from human faeces. For non-typhi salmonellae, MLCB is the best, single direct plating medium. XLD and MLCB, in combination, gave the highest isolation rate.Ĭonclusions: Where the earlier results of direct plating may be advantageous, XLD and MLCB provide the optimal combination. DCA was least specific, with only 9.01% of picks positive and greatest number of confirmatory tests. Isolation rates from XLD and DCA were only affected when the CF load was heavy. ABC proved highly specific, but insensitive, and isolation rates were adversely affected by any amount of CF. MLCB gave the highest isolation rate individually (84.8%) and amounts of competing flora (CF) did not affect the recognition of colonies. No isolates were recovered from direct plating that were not recovered via selenite enrichment. ![]() ![]() Results: Direct plating recovered 46 of the 60 possible isolates of Salmonella spp recovered via enrichment broth. Isolates of presumptive salmonellae were identified using standard laboratory techniques and the results were analysed statistically. Methods: Two thousand four hundred and nine routine, faecal samples received by four laboratories were inoculated on to xylose lysine desoxycholate (XLD), desoxycholate citrate (DCA), mannitol lysine crystal violet brilliant green (MLCB), and α-β chromogenic (ABC) agars using standardised protocols, reagents, and data collection. Aims: To compare the performance of four media, singly and in combination, as direct plating media for the isolation of Salmonella enterica from human faeces.
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