Ga. Evrendilek et al., Concurrent detection of Escherichia coli O157 : H7 and Salmonella from a single enrichment in 24 h, J FOOD SAF, 21(2), 2001, pp. 75-86
The objective of this study was to determine ifa single assay protocol coul
d result in the concurrent detection of Escherichia coli O157:H7 and Salmon
ella from a single sample grown in a single enrichment in 24 h. Twenty-Jive
and 375 g of ground beef nonfat dry milk, and dry pet food samples were se
eded with low (10 cfu/sample) and high (100 cfu/sample) levels off. coli 01
57:H7 and Salmonella cultures and incubated at 35 and 41C for 18 h for nons
elective preenrichment. Incubated samples were analyzed by immunomagnetic s
eparation (IMS) following a 6 h incubation for selective enrichment at 37C
using M-broth and enzyme linked immumosorbent assay (ELISA). Depending on t
he food samples and the inoculation level, the minimum concurrent detection
level off. coli O157:H7 and Salmonella was <I cfu/g in the samples at the
competitor flora level of 10(5) cfu/g or less in ground beef samples, but i
n other cases of higher competitor loads and low target inoculations E. col
i 0157:H7 could not be detected in the presence of the Salmonella.