Dynamics of salmonella isolation with modified Rappaport's medium (R10)

Abstract

Enhanced growth of salmonellas in Rappaport's medium as modified by Vassiliadis et al. (1976) after pre-enrichment in buffered peptone water during the first 6 h was obtained by replacement of tryptone by soya peptone. The competing bacteria, i.e. those which grow on brilliant green agar and which may interfere with the isolation of salmonellas when Rappaport's medium (R10) incubated at 43 degrees C is used for enrichment were inhibited or reduced in numbers when the normal amount of 5 g soya peptone/litre was used. When the amount was increased to 10 g/l, growth occurred, mainly of Enterobacter and Klebsiella species. The isolation of salmonellas was found to be largely dependent on the number and the ratio of their competitors. Every measure taken to reduce the number of competitive bacteria increases the possibility of isolating salmonellas. This explains the effect of improved selectivity of Rappaport's medium when small inocula are used. Rapid onset of growth of salmonellas by employing soya peptone introduces the possibility of using shorter incubation times 48 h.

An evaluation of commercially available dehydrated Rappaport-Vassiliadis medium for the isolation of salmonellae from poultry

“…However, when the enrichment cultures from the 50 samples which showed differences after 24 h incubation were plated after 48 h, the difference between all the media were reduced to nonsignificant levels (P >0-25). It has been suggested that incubation of RV medium can be limited to 24 h (Vassiliadis, 1983) and other workers have confirmed this when using RV-soya (van Schothorst & Renaud, 1983). In this study, however, a significant difference in the number of salmonella isolates obtained after 24 and 48 h was demonstrated for all three formulations of Rappaport's medium and we therefore suggest that incubation of enrichment cultures for the isolation of salmonellae from poultry samples should be extended to 48 h.…”

“…Although Rappaport stressed the importance of Bacto-tryptone in his medium (Rappaport, Konforti & Navon, 1956;Rappaport & Konforti, 1959) recent work has suggested that substitution of other peptones such as soya or mycological peptone may be beneficial (van Schothorst & Renaud, 1983). In comparisons of the efficiency of RV medium containing soya peptone (RV-soya) with that of the standard RV medium, we have demonstrated that RV-soya is a marginally better medium (Fricker & Girdwood, 1985;McGibbon, Quail & Fricker, 1984).…”

“…To many small laboratories a major disadvantage of RV medium has been that a commercially dehydrated medium has not been available. Recently, however, Oxoid Limited (Basingstoke, UK) have produced such a medium, based on the RV-soya medium described by van Schothorst & Renaud (1983). We have therefore compared the commercially produced medium (RV-Oxoid) with RV and RV-soya made from individual constituents in our own laboratories.…”

Salmonellas in Danish pigs: a comparison of three isolation methods

“…Modifications of the original medium of Rappaport, Konforth & Navon (1956) have been of particular interest, using high incubation temperature and small inoculum doses to reduce the number of competitive bacteria and increase the possibility of isolating salmonellas (Vassiliadis et al 1976; Harvey, Price & Xirouchaki, 1979;Vassiliadis et al 1981;van Schothorst & Renaud, 1983;Harvey & Price, 1983).…”

Acinetobacter Enfeksiyonlarında Dirençle İlgili Değişen Tanımlamalar ve Dirençte Güncel Durum

“…(15) ilk olarak 1976'da Rappaport'un Salmonella'lar için MgCl 2-malaşit yeşili zenginleştir-me besiyerine iki önemli modifikasyon getirdiklerinden beri diğer birçok araştırmacı besiyerinin dinamik ve kinetiğini araştırmış ve ek modifikasyonlar içeren besiyerlerinin verimliliğini karşılaştırmıştır. Bu ve buna benzer çalışmalar RV besiyerinin Salmonella'lar için (Salmonella serotip Typhi hariç) geleneksel zenginleştirme besiyerleri olan tetratiyonat ve selenit besiyerlerinden üstünlüğünü göstermiştir (15)(16)(17)(18)(19) . (20) .…”