Salmonella isolation with Rappaport's medium after pre-enrichment in buffered peptone water using a series of inoculum ratios

SUMMARYThe Rappaport-Vassiliadis enrichment medium (RV medium) in 10 ml quantities (RV/43°C, 10 ml) inoculated with 0-1 ml of pre-enrichment medium (P medium) was found more efficient in the isolation of salmonellae from 409 pre-enriched samples (mainly meat products), than the original Rappaport medium incubated at 43°C (R/43°C) and the RV medium in 5 ml quantities (RV/43°C, 5 ml) inoculated with 0-01 ml of P medium (P < 0-001, in both instances). Therefore, the inoculum from pre-enriched foods should not be less than 0-1 ml in 10 ml of RV medium.The RV/43°, 10 ml was also better (P < 0-01) in detecting samples containing salmonellas than the original Rappaport medium incubated at 37°C (R/37°C, 10 ml) and the modification R25 of R medium incubated at 37 'C. The R25 modification was used in 10 ml quantities (R25/37 'C, 10 ml) inoculated with 0-1 ml of P medium and in 5 ml quantities (R25/37°, 5 ml) inoculated with 0-01 ml of P medium. The last two R25 procedures were of the same efficiency in isolating salmonellas from meat products.

Section: Resultssupporting

confidence: 93%

A comparison of the original Rappaport medium (R medium) and the Rappaport–Vassiliadis medium (RV medium) in the isolation of salmonellae from meat products

Vassiliadis

Kalapothaki

Mavrommati

et al. 1984

“…The magnesium chloride, malachite green medium was the most successful of the three enrichment broths for the isolation of salmonellas in this study ( (90) 187 (89) 197 (94) 210 (100) Rappaport's medium must be used with a high inoculum ratio (Jameson, 1963;Harvey & Price, 1980). This term denotes the ratio of the volume of inoculum to the volume of the medium into which it is introduced.…”

Section: Resultsmentioning

confidence: 97%

Comparison of selenite F, Muller-Kauffmann tetrathionate and Rappaport's medium for salmonella isolation from chicken giblets after pre-enrichment in buffered peptone water

Harvey

Price

1981

Self Cite

SUMMARYSix hundred and eighty three samples of chicken giblets were examined for salmonellas. Three hundred and forty nine of these were neck and crop specimens and 334 were combined liver and heart samples. Two hundred and ten, in all, contained salmonellas.The technique of examination included pre-enrichment in buffered peptone water at 37°C for 18 h and subculture to three enrichment media: MullerKauffmann tetrathionate, selenite F and Rappaport's magnesium chloride malachite green broth. Inocula from buffered peptone water to 10 ml of tetrathionate and selenite were 1 ml in each case. The inoculum from the pre-enrichment medium to 10 ml of Rappaport was 0 005 ml. Tetrathionate and selenite were incubated at 43°C for 48 h. Rappaport's medium was incubated at 37°C for 48 h. Subcultures from all three enrichment broths were made at 24 h and 48 h to brilliant green MacConkey agar. Selective agars were incubated at 37°C for 24 h.The most successful technique for salmonella isolation used Rappaport's medium, which was significantly more efficient than either tetrathionate or selenite. This finding reinforces results obtained using sewage polluted natural water as test material and it is suggested that routine examination of environment samples for salmonellas could be based on Rappaport's medium alone.If S. typhi, S. dublin or subgenus III salmonellas were likely to be present in the sample, the technique described here would require modification.

“…The importance of inoculation ratios in the isolation of salmonellae has been demonstrated by many workers (Jameson, 1961;1963;Harvey & Price, 1980;Fricker, 1984a) and a ratio of 1: 100 has been recommended for RV medium (Vassiliadis, 1983). In this study, an inoculation ratio of 1: 100 was shown to be superior to 1:20, 1:50, 1:200 and 1: 1000 for isolating salmonellae from chicken giblets after pre-enrichment in buffered peptone water, for all three formulations of Rappaport's medium used.…”

Section: Discussionmentioning

confidence: 97%

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

Fricker¹,

Quail²,

McGibbon³

et al. 1985

SUMMARYA total of 745 samples of chicken giblets was cultured to determine the relative efficiency of a commercially available Rappaport-Vassiliadis medium (RV-Oxoid). Experiments to determine the optimum inoculation ratio showed that 1: 100 was superior to the other ratios tested. Comparison of RV-Oxoid with standard RV and RV-medium prepared using soya peptone (RV-soya) showed that after 24 h RV-soya was significantly better than RV-Oxoid (P < 0-05), although there was no significant difference between standard RV and RV-Oxoid. Furthermore, when the duration of incubation was extended to 48 h there was no significant difference between the three media (P > 0 25).We conclude that RV-Oxoid is a satisfactory product for the isolation of salmonellae from poultry, providing that it is inoculated at a ratio of 1: 100 and is incubated for 48h. Its use can therefore be recommended to laboratories who wish to use a dehydrated medium.