New Rapid Test Detects non-O157 E. Coli VTEC Serogroups

Thermo Scientific Limited has launched a new range of rapid diagnostic tests for the detection and identification of the most common non-O157 verocytotoxin-producing Escherichia coli (VTEC) serogroups. The Thermo Scientific Dryspot E. coli Seroscreen and Serocheck tests provide a fast and simple screening procedure for colonies isolated on culture plates, with clearly visible results in just 60 seconds.

Although E. coli O157:H7 is the most significant VTEC serotype associated with human disease, there are a number of additional O-serogroups that are often verocytotoxin producers - O26, O91, O103, O111, O128 and O145 are common examples. Standard procedures for the detection of E. coli O157 would not detect these serogroups.

Thermo Scientific Dryspot E. coli Seroscreen is a single screening kit that will detect the presence of any of these 6 common serogroups. The individual Thermo Scientific Dryspot E. coli Serocheck tests, one for each of the serogroups mentioned, are able to provide a specific identification.

For each test, the highly sensitive blue latex reagent is conveniently dried onto disposable reaction slides. Suspect colonies are simply suspended in a drop of buffer and mixed with the reagent on the slide. In the presence of the specific E. coli serogroup (any of the 6 serogroups for Seroscreen), the latex particles will agglutinate to provide a clearly visible positive result. If the test is negative the latex particles remain in smooth suspension.

Control latex, also dried onto the reaction slide, rules out false positive reactions due to non- specific reactions, whilst positive and negative controls (inactivated strains dried onto disposable mixing strips) ensure the correct working of the test.

The absence of 'wet' reagents allows the Thermo Scientific Dryspot E. coli Seroscreen and Serocheck tests to be stored conveniently at room temperature. Each kit contains sufficient materials for 60 tests (Seroscreen kit) or 15 tests (Serocheck kits).

The Thermo Scientific Dryspot E. coli Seroscreen and Serocheck tests are best used in conjunction with Enterohaemolysin or MacConkey Agar. Colonies for testing should have typical non-O157 E. coli appearance. In addition, the production of verocytotoxin can be confirmed using Thermo Scientific VTEC-RPLA or VTEC Screen Kit.