News Release: New Rapid Test Detects Non-O157 VTEC Serogroups

Oxoid 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 Oxoid Dryspot (tm) 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.

Oxoid Dryspot E. coli Seroscreen is a single screening kit that will detect

the presence of any of these 6 common serogroups. The individual Oxoid

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


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 Oxoid 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 Oxoid 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 Oxoid VTEC-RPLA or VTEC Screen Kit.

Further information about these products and Oxoid’s other products for the

water industry can be obtained from Oxoid Limited, Tel: +44 (0)1256 841144, Fax: +44 (0)1256 329728, email: or by visiting the Oxoid website at

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