An improved protocol for the detection and rapid confirmation within 48 h of Salmonellas in confectionery products

A modified ornithine decarboxylase broth and a selenite cystine trimethlyamine oxide ribose medium were developed to improve selection and detection of Salmonellas. They were used with a third medium, lysine iron cystine neutral red broth (incubated conventionally) in a screen of 80 Salmonellas and 32 non-salmonellas which showed the combination of media to be specific and sensitive. Subsequent evaluation with 90 product samples (spiked and naturally contaminated) resulted in complete agreement by rapid and conventional methods. The detected wells in these experiments were also used to evaluate a latex slide agglutination test for Salmonellas. Carried out directly on the well contents, this was found to be a rapid, specific and sensitive test for confirmation of Salmonella presence. Further tests with 106 routine production samples gave complete agreement by both methods. Presumptive positives were obtained in <1.0–3·8% of the sample wells and subsequent modification to the Bactometer software has greatly reduced these figures in routine use. The method is recommended for Salmonella testing of foodstuffs with low background flora and high fat/low moisture content.