Comparative Study of Micro-ID, Minitek and Conventional Methods with Enterobacteriaceae Freshly Isolated from Foods

A total of 400 Enterobacteriaceae isolates freshly taken from broiler carcasses, ground beef, pork sausage, raw shrimp, pre-wrapped sandwiches, raw carrots, lettuce and fresh strawberries was inoculated into the 15 biochemical tests of the Micro-ID (4-h) system and into the 15 corresponding tests in the Minitek (24-h) and conventional systems. For each food there were 750 biochemical test comparisons (50 isolates × 15 tests). The overall agreement between Micro-ID and conventional tests was 96.8%, whereas the agreement between Minitek and conventional tests was 93.6%. Three laboratory technicians who independently recorded results of 6000 biochemical tests from each of the three systems were in complete agreement for 99.3%, 98.9% and 99.7% of the Micro-ID. Minitek and conventional tests, respectively. Thus results obtained with the miniaturized systems were as easy to read and interpret as conventional tests in tubes. The most frequently encountered Enterobacteriaceae from these foods were Escherichia coli (broiler carcasses, pork sausage). Enterobacter agglomerans (carrots, lettuce, shrimp, strawberries), Enterobacter cloacae (pre-wrapped sandwiches), and Serratia liquefaciens (ground beef).