Comparison of selenite F, Muller-Kauffmann tetrathionate and Rappaport's medium for the isolation of salmonellas from sewage-polluted natural water using a pre-enrichment technique

SUMMARYThe relative efficiency of three selective enrichment broths (Muller-Kauffmann tetrathionate, Rappaport's and selenite F) was investigated for the isolation of salmonellae from seagull cloacal swabs. Pre-enrichment in buffered peptone water was employed throughout the study, which involved the examination of 560 gulls, sixty (10-7%) of which were found to be carrying salmonellae. Rappaport's broth as modified by Vassiliadis for incubation at 43 'C (Vassiliadis et al. 1976) yielded the highest number of positive swabs (57) and the widest range of serotypes. It was significantly more efficient that either selenite F or tetrathionate broth, although the results obtained with Rappaport's broth incubated at 37 and 43°C did not differ significantly (P > 0 5). Eleven serotypes were isolated during. the study, the most prevalent being Salmonella virchow.

Section: Resultscontrasting

confidence: 77%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A comparison of enrichment media for the isolation of salmonellae from seagull cloacal swabs

Fricker

Girdwood

Munro

1983

“…The 24 h subculture is more convenient than the 6 h for laboratory routine. The technique is simple and the 16 % gain (Table 1) compares favourably with the 2-6 % gain obtained in an earlier study by subculture from Rappaport's enrichment at 24 and 48 h (Harvey, Price & Xirouchaki, 1979). In contrast to selenite F and Muller-Kauffmann tetrathionate, 24 h appears to be near the optimum timing for subculture from Rappaport.…”

Section: Discussionsupporting

confidence: 62%

Multiple plating from enrichment media as an aid to salmonella isolation

Price

1983

Self Cite

SUMMARYFaeces samples enriched for salmonellas in selenite F broth incubated at 43°C were subcultured to brilliant green MacConkey agar after 6 h. Four platings were made. As a control technique, each sample was enriched in selenite F incubated at 37°C for 24 h and subcultured once to brilliant green MacConkey agar. Of the specimens plated at 6 h, out of a total of 25 positive samples, 6 required more than a single subculture to reveal the presence of salmonellas. Twenty-four positive isolations were made from the selenite broths incubated at 37°C for 24 h and subcultured once only. All faecal samples positive by enrichment were also positive by direct plating. Nine samples seeded by 6 h produced only 1-2 salmonella colonies per plate. Convalescent specimens are, therefore, unlikely to be efficiently diagnosed by early subculture even if it is combined with multiple plating.River Taff samples, after pre-enrichment in buffered peptone water, were enriched in Rappaport's medium at 37°C for 6 h. Subcultures were made to four plates of brilliant green MacConkey agar. A control subculture was made at 24 h to a single plate of brilliant green MacConkey. Although multiple subculture at 6 h improved salmonella isolation, the method was not as efficient as a single plating from the same enrichment culture at 24 h. There was no evidence that subculture at 6 h combined with multiple plating had a value either for faecal examination or for the isolation of salmonellas from sewage-polluted natural water.Samples of other natural waters submitted routinely by Environmental Health Officers were pre-enriched in buffered peptone water before subculture to Rappaport's medium. The enrichment cultures were incubated at 37°C for 24 h and duplicate platings were made to brilliant green MacConkey agar. By double plating at 24 h, a gain of 16 % in salmonella recovery was made. This compares favourably with the gain obtained by subculture from Rappaport after 24 and 48 h incubation. It also saves 24 h in examination time.

“…Whilst it has been suggested that commercially prepared products are often not as efficient as those produced from individual constituents (Harvey, Price & Xirouchaki, 1979) their convenience makes their use desirable. However, before any dehydrated product is used for routine work its efficiency should be compared with the same medium prepared from individual constituents.…”

Section: Discussionmentioning

confidence: 99%

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.