Abstract
To establish an efficient method for detection and isolation of Salmonella in feed and food manufacturing plant, we evaluated the delayed secondary enrichment (DSE) method, which has already been acknowledged in the field of poultry hygiene. In order to evaluate the detection rate by the increase of pre-enrichment culture and selective enrichment broth, the oilmeal samples (n=182) were examined using different volume (10 ml and 90 ml) of the Hajna-tetrathionate broth (HTT). As a result, the sample with different result was only two (1.1%). The detection sensitivities of these 2 methods were same (p<0.05). We examined oilseed (n=34) and swab samples (n=92) of environment in the oilmeal manufacturing plant. The DSE method alone showed the highest rate of Salmonella detection at 14.3% (18/126), followed by the HTT-DHL method and HTT-CHROMagar Salmonella method, both at 12.7% (16/126). Moreover, O antigen group of isolates detected by the DSE method was different from those of HTT-DHL method in 7 samples. It was found that the detection sensitivity of the DSE method was high. Our findings suggest that O antigen group of isolates detected by the DSE method may differ from those of conventional enrichment methods. We conclude that DSE method is a simple and efficient method for epidemiological investigations of Salmonella in environments, such as food manufacturing plants.
