Isolation of Salmonella with the use of 100 ml of the R10 modification of Rappaport's enrichment medium

Publisher Website
Google Scholar
Abstract
Summary: One hundred and eighty samples of pork sausages were examined after preenrichment in buffered peptone water (P medium), for the presence of salmonellas. From each pre-enrichment four enrichments were made: (1) 0·1 ml of P medium was inoculated into 10 ml of Rappaport's medium, formula R10 (R10/43 °C), (2) 1 ml of the P medium was added to 100 ml of R10 broth (R10/100 ml/43 °C), (3) 1 ml of P medium was inoculated into 10 ml of Muller-Kauffmann tetrathionate broth (MK medium) prepared in accordance with the International Standards Organization document ISO 3565 (MK/43 °C) and (4) 10 ml of P medium were added to 100 ml of MK broth (MK/100 ml/43 °C). All the enrichments were incubated at 43 °C for 48 h. Forty-six and 47 samples were found positive with the first two enrichment methods (R10/43 °C and R10/100 ml/43 °C), while only 16 samples were found positive with the method MK/43 °C, and 27 with the method MK/100 ml/43 °C. The superiority of either one of the two R10 procedures over either one of the two MK methods is statistically highly significant (paired χ2; P < 0·001 in all four comparisons). The superiority of procedure MK/100 ml/43 °C over the method MK/43 °C is also statistically significant (P < 0·005). Both R10/43 °C and R10/100 ml/43 °C procedures had a much stronger inhibitory effect on the competing organisms (lactose- and sucrosenegative) than the two MK methods.