Inadequacy of small transfer volume and short (6 h) selective enrichment for the detection of foodborne Salmonella
1992
D'Aoust, J.Y. | Sewell, A.M. | Daley, E.
The propensity of short (6 h) selective enrichment combined with a preenrichment to enrichment transfer volume ratio of 1:100 to provide greater method brevity could not be demonstrated. Inoculation of tetrathionate brilliant green (35 and 43 degrees C), Rappaport-Vassiliadis (43 degrees C), and selenite cystine (35 degrees C) enrichment broths (9.0 ml) with 0.1 ml of preenrichment culture and incubation for 6 h identified, respectively, 107 (84.9%), 104 (82.5%), 112 (88.9%), and 113 (89.7%) of the 126 contaminated samples detected in the present study; homologous results with the 1.0-ml transfer volume showed a marginal increase in sensitivity. Recoveries of foodborne salmonellae with the standard (24-h) period of selective enrichment were generally transfer volume-independent and consistently exceeded that obtained with 6-h enrichment cultures. Results further underlined the importance of enrichment at an elevated (43 degrees C) temperature for the effective repression of competitive microflora, and the facilitated isolation of Salmonella on plating media.
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