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The Rappaport—Vassiliadis (RV) enrichment medium for the isolation of salmonellas: An overview
Author(s) -
Vassiliadis P.
Publication year - 1983
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1983.tb01302.x
Subject(s) - tetrathionate , rappaport , malachite green , food science , brilliant green , isolation (microbiology) , agar , selenium , chemistry , salmonella , microbiology and biotechnology , biology , bacteria , philosophy , genetics , theology , organic chemistry , adsorption
In 1976 two major modifications were introduced in the composition and use of Rappaport's magnesium chloride—malachite green enrichment medium for salmonellas. One modification consisted of the reduction to one‐third of the amount of malachite green contained in the original formulation of Rappaport's medium, and the other in the incubation at 43 instead of 37°C. Since 1980, the modified medium incubated at 43°C is known as RV (Rappaport—Vassiliadis) enrichment medium for salmonellas. From 1977 to 1981, in eleven studies, the RV enrichment broth has been compared to the standardized Muller‐Kauffmann tetrathionate broth (MK broth) recommended as a reference method by the International Standards Organization, for the isolation of salmonellas from meat products, after pre‐enrichment in buffered peptone water. In all these studies the RV broth was superior to the MK broth in the isolation of salmonellas from naturally contaminated meat products (bovine minced meat, pork sausages, mesenteric lymph nodes, chicken carcases), sewage and faeces of healthy pigs, after pre‐enrichment in buffered peptone water. This superiority was statistically significant in seven of the eleven trials. Furthermore, in three more investigations the RV medium was compared with Oxoid selenite broth, with Difco tetrathionate broth and Difco selenite‐cystine broth. In all these three investigations the RV medium was superior for isolation of salmonellas, after pre‐enrichment, from naturally contaminated meat products and animal feeds. The superiority was statistically highly significant. When dealing with meat products, the RV medium in 10 ml volume inoculated with 0.1 ml of the pre‐enrichment medium, proved to be as effective as the RV medium in 100 ml volume, inoculated with 1 ml of pre‐enrichment medium, and clearly superior to the MK broth in 100 ml quantity. In all these studies involving enrichment in RV medium, MK broth, Difco tetrathionate broth, Oxoid selenite broth, incubated at 43°C and Difco selenite‐cystine broth incubated at 37°C, the RV medium proved to be highly specific. This means that the RV medium inhibits much more strongly the competing organisms, (including ‘ Proteus hauseri ’) which are lactose‐ and sucrose‐negative on the selective media and which may produce salmonella‐like colonies.