Comparison of three plating media for the isolation of Salmonella from poultry environmental samples in Great Britain using ISO 6579:2002 (Annex D).
Carrique-Mas JJ., Barnes S., McLaren I., Davies R.
AIMS: To evaluate the performance of three Salmonella plating media (Rambach, Xylose Lysine Deoxycholate agar and modified Brilliant Green Agar plus Novobiocin) as part of the ISO 6579: 2002 (Annex D) on poultry environmental samples. METHODS AND RESULTS: The samples analysed were those for the European Union Salmonella baseline surveys of laying (N = 3087), broiler (N = 1550), turkey fattening (N = 1540) and turkey breeding (N = 580) flocks for Great Britain. Results were considered separately for Rambach (including and excluding pale orange colonies) and for growth on selective media [Modified semi-solid Rappaport Vassiliadis (MSRV)] after 24 and 48 h of incubation. Overall, Rambach was the most sensitive medium, provided that pale orange colonies were checked. In all cases, an increase in the sensitivity of detection was obtained by plating growth on MSRV after 48 h of incubation. In broilers and laying flocks, the specificity significantly improved when Rambach only was used. CONCLUSION: The use of Rambach results in considerable savings compared with the two-plate method prescribed by ISO 6579:2002 (Annex D) without compromising sensitivity. SIGNIFICANCE AND IMPACT OF THE STUDY: Salmonella isolation protocols should be reviewed in terms of their efficiency and cost.