Importance of pre-enrichment media for isolation of Salmonella spp. from swine and poultry

The performance of two new (1-day) culture methods, Salmonella Enrichment Broth (SEB) and Revive, and an alternative pre-enrichment broth, designated Universal pre-enrichment broth (UB), was compared to the internationally accepted buffered peptone water (BPW). The study was directed towards detection of Salmonella in 100 faecal samples from porcine and 100 neck-skin samples from poultry. The sensitivity (number of positive cases per method among all the positive cases) of the conventional pre-enrichment in BPW was found to be 0.77 for swine and 0.66 for poultry samples, while a combination of the BPW method with parallel pre-enrichment of the same sample in UB resulted in high sensitivity for swine (0.92) and poultry (0.95) samples. A 2-h pre-enrichment in the non-selective Revive, followed by overnight enrichment in selective broth, resulted in a low sensitivity, particularly for the neck-skin samples (0.16, P=0.001). The SEB method in the porcine samples resulted in a sensitivity (0.71) comparable to the standard method (P=0.31). In conclusion, additional pre-enrichment of samples in UB may substantially increase the culture sensitivity. During routine screening of large numbers of samples, it may be advantageous to use SEB rather than standard culturing.